Ugunduzi wa Erasto Mpemba, (Maji ya moto kuganda haraka kuliko ya baridi) 'The Mpemba Effect' kwanini hatukufundishwa mashuleni?
Ugunduzi wa Erasto Mpemba, (Maji ya moto kuganda haraka kuliko ya baridi) 'The Mpemba Effect' kwanini hatukufundishwa mashuleni?
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YEHODAYA
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Kwa wasomi wa fizikia mtanzania mwenzetu Erasto Mpemba yumo kwenye vitabu kwa ugunduzi wake wa ambao umepewa jina la mpemba effect kwenye tasnia ya fizikia.Kwa ugunduzi ule anastahili kabisa kupewa nishani ya Nobel lakini hakuna wa kumrecommend.Napendekeza serikali na maprofesa watanzania pelekeni hilo jina La Erasto Mpemba.Ukiggoogle popote utampata.Serikali pia impe nishani kwa kuiingiza Tanzania kwenye vitabu vya fizikia dunia nzima akitambuliwa kama wakina Newton Law nk na yeye iko yake ya Mpemba effect
Mpemba’s baffling discovery: can hot water freeze before cold? (1969)
Posted on May 31, 2011 by skullsinthestars
“My name is Erasto B Mpemba, and I am going to tell you about my discovery, which was due to misusing a refrigerator.”
With those words, Tanzanian student Erasto Mpemba entered scientific history, and also sparked a scientific mystery and controversy that remains ongoing today, some 40 years later!
The phenomenon Mpemba found is now known as the Mpemba effect, and is the very counterintuitive idea that, under certain circumstances, a quantity of very hot/boiling liquid can freeze faster than an equal quantity of cold liquid!
How is this possible? The remarkable thing is that nobody really knows, even though the first observations were reported to the scientific community in 1969. The story of the discovery, and the consequent mystery, is worth a bit of exploration — and the Mpemba effect carries numerous important lessons about the nature and method of scientific discovery.
Mpemba made his accidental discovery in Tanzania in 1963, when he was only 13 years old and in secondary school. In spite of widespread disdain from his classmates, he surreptitiously continued experiments on the phenomenon until he had the good fortune in high school to interact with Professor Denis Osborne of the University College Dar es Salaam. Osborne was intrigued, carried out his own experiments, and in 1969 the two published a paper in the journal Physics Education.
This article is, in my opinion, one of the most remarkable in all of the history of physics. Aside from its title, “Cool?”, it is also unusual in being presented in two parts: Mpemba gives a first person account in his own words of his discovery in the first half, and Osborne picks up the story and describes the follow-up experiments in the second half. Mpemba’s own account is so charming and fascinating that it is worth quoting from liberally:
My name is Erasto B Mpemba, and I am going to tell you about my discovery, which was due to misusing a refrigerator. All of you know that it is advisable not to put hot things in a refrigerator, for you somehow shock it; and it will not last long.
In 1963, when I was in form 3 in Magamba Secondary School, Tanzania, I used to make ice-cream. The boys at the school do this by boiling milk, mixing it with sugar and putting it into the freezing chamber in the refrigerator, after it has first cooled nearly to room temperature. A lot of boys make it and there is a rush to get space in the refrigerator.
One day after buying milk from the local women, I started boiling it. Another boy, who had bought some milk for making ice-cream, ran to the refrigerator when he saw me boiling up milk and quickly mixed his milk with sugar and poured it into the icetray without boiling it; so that he may not miss his chance. Knowing that if I waited for the boiled milk to cool before placing it in the refrigerator I would lose the last available ice-tray, I decided to risk ruin to the refrigerator on that day by putting hot milk into it. The other boy and I went back an hour and a half later and found that my tray of milk had frozen into ice-cream while his was still only a thick liquid, not yet frozen.
I asked my physics teacher why it happened like that, with the milk that was hot freezing first, and the answer he gave me was that “You were confused, that cannot happen”. Then I believed his answer.
Here we have the beginnings of a classic story of science — an accidental discovery, scoffed at by the “establishment scientists”.
Mpemba might have given up at that point, but he encountered a friend who sold ice cream for a living, and that friend happened to mention that many vendors would use boiling water to make their ice cream! It was already common knowledge amongst them, apparently, that a boiling mixture could freeze quicker.
After passing my O level examination, I was chosen to go to Mkwawa High School in Iringa. The first topics we dealt with were on heat. One day as our teacher taught us about Newton’s law of cooling, I asked him the question, “Please, sir, why is it that when you put both hot milk and cold milk into a refrigerator at the same time, the hot milk freezes first?” The teacher replied: “I do not think so, Mpemba.” I continued: “It is true, sir, I have done it myself” and he said: “The answer I can give is that you were confused.” I kept on arguing, and the final answer he gave me was that: “Well, all I can say is that that is Mpemba’s physics and not the universal physics.” From then onwards if I failed in a problem by making a mistake in looking up the logarithms this teacher used to say: “That is Mpemba’s mathematics.”
And the whole class adopted this, and anytime I did something wrong they used to say to me “That is Mpemba’s…”, whatever the thing was.
Here the high school teacher failed miserably — ridiculing a student is pretty much the worst thing one can do in a science classroom! Fortunately, Mpemba was not deterred:
Then one afternoon found the biology laboratory open, and there was no teacher. I took two 50 cm³ beakers, one I filled with cold water from the tap and the other with hot water from a boiler and quickly put them in the freezing chamber of the laboratory refrigerator. After one hour I came back to look and I found that not all the water had been changed into ice, but that there was more ice in the beaker which had hot water to start with than in the one which had cold water. This was not really conclusive. So, I planned to try it again when I had the chance.
Before he had this chance, however, Professor Osborne came to lecture on physics, giving Mpemba a valuable opportunity:
When Dr Osborne visited our school we were allowed to ask him some questions, mainly in physics. I asked: “If you take two similar containers with equal volumes Of water, one at 35 °C and the other at 100 °C, and put them into a refrigerator, the one that started at 100 °C freezes first. Why?” He first smiled and asked me to repeat the question. After I repeated it he said: “Is it true, have you done it?” I said: “Yes.” Then he said: “I do not know, but I promise to try this experiment when I am back in Dar es Salaam.” Next day my classmates in form six were saying to me that I had shamed them by asking that question and that my aim was to ask a question which Dr Osborne would not be able to answer. Some said to me: “But Mpemba did you understand your chapter on Newton’s law of cooling?” I told them: “Theory differs from practical.” Some said : “We do not wonder, for that was Mpemba’s physics.”
There are many remarkable points in this short passage. First of all, we see an admirable open-mindedness of Professor Osborne in his dealings with Mpemba, and that open-mindedness would quickly benefit them both. Conversely, we see a dangerous “groupthink” amongst Mpemba’s classmates regarding science, in which they are genuinely offended by Mpemba questioning the status quo. Mpemba shows great wisdom in his answer: “Theory differs from practical”. This is an important point for anyone studying physics: we like to create simplified models to explain nature, but those models often lose real-world aspects in the process of stripping them down.
Mpemba actually continued his experiments in a kitchen refrigerator, with the permission of kitchen staff, and convinced his classmates and the headmaster of his school of the accuracy of his findings.
At Dar es Salaam, Osborne was true to his word and looked into the phenomenon himself. As he notes in the continuation of the paper,
It seemed an unlikely happening, but the student insisted that he was sure of the facts. I confess that I thought he was mistaken but fortunately remembered the need to encourage students to develop questioning and critical attitudes. No question should be ridiculed. In this case there was an added reason for caution, for everyday events are seldom as simple as they seem and it is dangerous to pass a superficial judgment on what can and cannot be. I said that the facts as they were given surprised me because they appeared to contradict the physics I know. But I added that it was possible that the rate of cooling might be affected by some factor I had not considered.
Osborne sets a great example for all physics educators! It can be difficult at times, but “No question should be ridiculed” would be a great part of a “Hippocratic oath” for teachers.
One other anecdote from Osborne’s account is worth quotation:
At the University College in Dar es Salaam I asked a young technician to test the facts. The technician reported that the water that started hot did indeed freeze first and added in a moment of unscientific enthusiasm: “But we’ll keep on repeating the experiment until we get the right result.”
I leave it as an exercise to the reader to explain what is scientifically wrong with the technician’s attitude!
So what did Osborne’s research show? He placed a 100 cm³ beaker filled with 70 cm³ of water on a sheet of insulating foam in a freezer, and timed how long it took for the water to freeze. For temperatures up to 20 °C, the time was roughly proportional to the temperature above freezing, up to a maximum of 100 minutes at 20 °C. For higher temperatures, however, the time dropped dramatically, down to 40 minutes for 80 °C water!
Later experiments on the effect have been far less conclusive than Mpemba and Osborne’s. Some have seen similar results, while others have observed no effect at all! The appearance of the Mpemba effect apparently depends very strongly on the specific experimental circumstances, and is much harder to reproduce than the original paper would imply. A number of physicists seem skeptical that the effect truly exists at all!
With this in mind, however, it is worth noting that Mpemba’s observation was in fact noted earlier by others over the course of the past two thousand years. Around 350 B.C.E., Aristotle, in giving an explanation of hail in his book “Meteorology”¹, noted:
The fact that the water has previously been warmed contributes to its freezing quickly; for so it cools sooner. (Hence many people, when they want to cool water quickly, begin by putting it in the sun. So the inhabitants of Pontus when they encamp on the ice to fish (they cut a hole in the ice and then fish) pour warm water round their rods that it may freeze the quicker; for they use the ice like lead to fix the rods.) Now it is in hot countries and seasons that the water which forms soon grows warm.
Others who argued for the existence of a Mpemba effect, under some circumstances, include Roger Bacon in the 13th century, and Francis Bacon and René Descartes in the 17th century. It was Mpemba and Osborne, however, who brought it to the attention of modern science.
Before delving into some of the explanations for the effect, it is important to explain why the natural objection to its existence is not necessarily applicable. A natural argument is as follows. “Suppose we have two equal glasses of water, one at 100 °C and one at 30 °C. In order for the water at 100 °C to freeze, it must first cool to 30 °C. The time it takes to freeze is therefore the amount of time it takes to go from 100 to 30 plus the time it takes to go from 30 to zero. It therefore must take longer to freeze than the 30 °C water.”
The flaw in this argument is assuming that a body of water is only characterized by a single parameter: its temperature. In general, there are other characteristics of the water that could be changed due to its heating; for instance, the amount of gas in solution, the presence of other solutes, the presence of convection currents, gradients of the distribution of temperature in the container. Any, all, or none of these may in fact be the culprit, but it is important to realize that a body of water not in thermal equilibrium may have its behavior characterized by a number of different properties.
A number of hypotheses have been proposed as explanations, some based on the factors mentioned:
1. Convective heat transfer. When a liquid is heated, it can form convection currents that rapidly bring the hot liquid to the surface, where the heat is lost by evaporation:
Osborne noted that this convection will keep the top of the liquid hotter than the bottom, even when the temperature matches an initially cold liquid that doesn’t possess this convection cooling. This results in a faster rate of cooling that could, under the right circumstances, result in Mpemba’s observation.
2. Evaporation. A boiling or very hot liquid will lose some of its mass due to evaporation. With a lower mass, it will cool faster, possibly giving a “boost” to the Mpemba effect. Osborne already noted that evaporation alone could not account for all of the rate of cooling of the hot liquid.
3. Degassing. In a series of experiments in 1988, a Polish research group² reproduced the Mpemba effect and noted that the effect depended strongly on the amount of gas dissolved in the water. When the water was purged of air and carbon dioxide, the time to freeze became proportional to the starting temperature. The researchers suggested that the presence of gas was substantially slowing the rate of cooling, and that the heated water was purged of it.
4. Supercooling. In 1995, German scientist David Auerbach proposed³ that the Mpemba effect could be explained by supercooling, and performed experiments to back up the assertion.
Liquids begin to crystallize into a solid at the freezing point with the help of impurities around which the crystals can nucleate. In the absence of such impurities, the liquid can be cooled below its normal freezing point while remaining a liquid — it is “supercooled”. Auerbach suggests that the cold water will supercool to a lower temperature than the hot water, thus giving the hot water an “edge”. However, the reason that hot water has a higher supercooling temperature is unclear, and possibly related to the earlier noted effects.
5. Distribution of solutes. In 2009, an interesting explanation was proposed4 by J.I. Katz, who suggested that solutes present in the cold water slow the freezing process, as suggested earlier, but also that those solutes get driven from the freezing water into the as-yet unfrozen water, slowing the process further.
Other suggestions have been made, and other experiments have been done5, though no consensus seems to have been reached regarding the origins and generality of the effect. The confusion about the Mpemba effect is curiously reminiscent of the controversy around the “Archimedes death ray” controversy we have discussed earlier — the answer depends on the question being asked. Does hot water always freeze faster than cold? Almost certainly not! Are there some circumstances under which hot water freezes faster than cold? It seems likely, though nobody is sure exactly what those circumstances are. Does a negative result disprove the Mpemba effect, or was the experiment just done under the wrong circumstances? Nobody knows for certain.
The controversy no longer is of concern to Erasto Mpemba, however, who did not become a physicist himself but ended up studying at the College of African Wildlife Management. With his education, he eventually became the Principal Game Officer for the Tanzanian Ministry of Natural Resources and Tourism, working on wildlife management and conservation.
Erasto Mpemba, circa 1997 (source).
Regardless of the mystery, Mpemba’s discovery is a wonderful illustration of many important lessons in science: the significance of experiment over theory, the danger of clinging to preconceived notions, the difficulty in evaluating even seemingly simple real-world physics problems, and the importance of perseverance in the face of unreasoning denial. Furthermore, as far as I know the Mpemba effect is one of the only (if not the only) physical phenomena named after an African researcher! It is a wonderful and frustrating hint of how much intellectual potential lies untapped on the continent.
So what do I think of all the controversy? I’m not quite sure what to think! I’d love to test the Mpemba effect myself at home, but our freezer is packed to capacity6! Any enterprising experimenters out there want to give it a try? Describe your results in the comments!
********************
(Thanks to Blake Stacey for providing one of the references used to write this post!)
¹ Aristotle, “Meteorology”, in The Complete Works of Aristotle (The revised Oxford translation), (J. Barnes, ed., Princeton University Press, 1984).
² Wojciechowski, Owczarek and Bednarz, “Freezing of aqueous solutions containing gases,” Cryst. Res. Technol. 23 (1988), 843-848.
³ D. Auerbach, “Supercooling and the Mpemba effect: When hot water freezes quicker than cold,” Am. J. Phys. 63 (1995), 882-885.
4 J.I. Katz, “When hot water freezes before cold,” Am. J. Phys. 77 (2009), 27-29.
5 Esposito, De Risi and Somma, “Mpemba effect and phase transitions in the adiabatic cooling of water before freezing,” Physica A 387 (2008), 757-763.
6 This is a clear indication of my current marital status. Back in my single days, the only thing you would find in my freezer would have been a pair of frozen pizzas!
E.B. Mpemba, & D.G. Osborne (1969). Cool? Physics Education, 4, 172-175
mwenyewe huyo hapo
Mpemba’s baffling discovery: can hot water freeze before cold? (1969)
Posted on May 31, 2011 by skullsinthestars
“My name is Erasto B Mpemba, and I am going to tell you about my discovery, which was due to misusing a refrigerator.”
With those words, Tanzanian student Erasto Mpemba entered scientific history, and also sparked a scientific mystery and controversy that remains ongoing today, some 40 years later!
The phenomenon Mpemba found is now known as the Mpemba effect, and is the very counterintuitive idea that, under certain circumstances, a quantity of very hot/boiling liquid can freeze faster than an equal quantity of cold liquid!
How is this possible? The remarkable thing is that nobody really knows, even though the first observations were reported to the scientific community in 1969. The story of the discovery, and the consequent mystery, is worth a bit of exploration — and the Mpemba effect carries numerous important lessons about the nature and method of scientific discovery.Mpemba made his accidental discovery in Tanzania in 1963, when he was only 13 years old and in secondary school. In spite of widespread disdain from his classmates, he surreptitiously continued experiments on the phenomenon until he had the good fortune in high school to interact with Professor Denis Osborne of the University College Dar es Salaam. Osborne was intrigued, carried out his own experiments, and in 1969 the two published a paper in the journal Physics Education.
This article is, in my opinion, one of the most remarkable in all of the history of physics. Aside from its title, “Cool?”, it is also unusual in being presented in two parts: Mpemba gives a first person account in his own words of his discovery in the first half, and Osborne picks up the story and describes the follow-up experiments in the second half. Mpemba’s own account is so charming and fascinating that it is worth quoting from liberally:
My name is Erasto B Mpemba, and I am going to tell you about my discovery, which was due to misusing a refrigerator. All of you know that it is advisable not to put hot things in a refrigerator, for you somehow shock it; and it will not last long.
In 1963, when I was in form 3 in Magamba Secondary School, Tanzania, I used to make ice-cream. The boys at the school do this by boiling milk, mixing it with sugar and putting it into the freezing chamber in the refrigerator, after it has first cooled nearly to room temperature. A lot of boys make it and there is a rush to get space in the refrigerator.
One day after buying milk from the local women, I started boiling it. Another boy, who had bought some milk for making ice-cream, ran to the refrigerator when he saw me boiling up milk and quickly mixed his milk with sugar and poured it into the icetray without boiling it; so that he may not miss his chance. Knowing that if I waited for the boiled milk to cool before placing it in the refrigerator I would lose the last available ice-tray, I decided to risk ruin to the refrigerator on that day by putting hot milk into it. The other boy and I went back an hour and a half later and found that my tray of milk had frozen into ice-cream while his was still only a thick liquid, not yet frozen.
I asked my physics teacher why it happened like that, with the milk that was hot freezing first, and the answer he gave me was that “You were confused, that cannot happen”. Then I believed his answer.
Here we have the beginnings of a classic story of science — an accidental discovery, scoffed at by the “establishment scientists”.
Mpemba might have given up at that point, but he encountered a friend who sold ice cream for a living, and that friend happened to mention that many vendors would use boiling water to make their ice cream! It was already common knowledge amongst them, apparently, that a boiling mixture could freeze quicker.
After passing my O level examination, I was chosen to go to Mkwawa High School in Iringa. The first topics we dealt with were on heat. One day as our teacher taught us about Newton’s law of cooling, I asked him the question, “Please, sir, why is it that when you put both hot milk and cold milk into a refrigerator at the same time, the hot milk freezes first?” The teacher replied: “I do not think so, Mpemba.” I continued: “It is true, sir, I have done it myself” and he said: “The answer I can give is that you were confused.” I kept on arguing, and the final answer he gave me was that: “Well, all I can say is that that is Mpemba’s physics and not the universal physics.” From then onwards if I failed in a problem by making a mistake in looking up the logarithms this teacher used to say: “That is Mpemba’s mathematics.”
And the whole class adopted this, and anytime I did something wrong they used to say to me “That is Mpemba’s…”, whatever the thing was.
Here the high school teacher failed miserably — ridiculing a student is pretty much the worst thing one can do in a science classroom! Fortunately, Mpemba was not deterred:
Then one afternoon found the biology laboratory open, and there was no teacher. I took two 50 cm³ beakers, one I filled with cold water from the tap and the other with hot water from a boiler and quickly put them in the freezing chamber of the laboratory refrigerator. After one hour I came back to look and I found that not all the water had been changed into ice, but that there was more ice in the beaker which had hot water to start with than in the one which had cold water. This was not really conclusive. So, I planned to try it again when I had the chance.
Before he had this chance, however, Professor Osborne came to lecture on physics, giving Mpemba a valuable opportunity:
When Dr Osborne visited our school we were allowed to ask him some questions, mainly in physics. I asked: “If you take two similar containers with equal volumes Of water, one at 35 °C and the other at 100 °C, and put them into a refrigerator, the one that started at 100 °C freezes first. Why?” He first smiled and asked me to repeat the question. After I repeated it he said: “Is it true, have you done it?” I said: “Yes.” Then he said: “I do not know, but I promise to try this experiment when I am back in Dar es Salaam.” Next day my classmates in form six were saying to me that I had shamed them by asking that question and that my aim was to ask a question which Dr Osborne would not be able to answer. Some said to me: “But Mpemba did you understand your chapter on Newton’s law of cooling?” I told them: “Theory differs from practical.” Some said : “We do not wonder, for that was Mpemba’s physics.”
There are many remarkable points in this short passage. First of all, we see an admirable open-mindedness of Professor Osborne in his dealings with Mpemba, and that open-mindedness would quickly benefit them both. Conversely, we see a dangerous “groupthink” amongst Mpemba’s classmates regarding science, in which they are genuinely offended by Mpemba questioning the status quo. Mpemba shows great wisdom in his answer: “Theory differs from practical”. This is an important point for anyone studying physics: we like to create simplified models to explain nature, but those models often lose real-world aspects in the process of stripping them down.
Mpemba actually continued his experiments in a kitchen refrigerator, with the permission of kitchen staff, and convinced his classmates and the headmaster of his school of the accuracy of his findings.
At Dar es Salaam, Osborne was true to his word and looked into the phenomenon himself. As he notes in the continuation of the paper,
It seemed an unlikely happening, but the student insisted that he was sure of the facts. I confess that I thought he was mistaken but fortunately remembered the need to encourage students to develop questioning and critical attitudes. No question should be ridiculed. In this case there was an added reason for caution, for everyday events are seldom as simple as they seem and it is dangerous to pass a superficial judgment on what can and cannot be. I said that the facts as they were given surprised me because they appeared to contradict the physics I know. But I added that it was possible that the rate of cooling might be affected by some factor I had not considered.
Osborne sets a great example for all physics educators! It can be difficult at times, but “No question should be ridiculed” would be a great part of a “Hippocratic oath” for teachers.
One other anecdote from Osborne’s account is worth quotation:
At the University College in Dar es Salaam I asked a young technician to test the facts. The technician reported that the water that started hot did indeed freeze first and added in a moment of unscientific enthusiasm: “But we’ll keep on repeating the experiment until we get the right result.”
I leave it as an exercise to the reader to explain what is scientifically wrong with the technician’s attitude!
So what did Osborne’s research show? He placed a 100 cm³ beaker filled with 70 cm³ of water on a sheet of insulating foam in a freezer, and timed how long it took for the water to freeze. For temperatures up to 20 °C, the time was roughly proportional to the temperature above freezing, up to a maximum of 100 minutes at 20 °C. For higher temperatures, however, the time dropped dramatically, down to 40 minutes for 80 °C water!
Later experiments on the effect have been far less conclusive than Mpemba and Osborne’s. Some have seen similar results, while others have observed no effect at all! The appearance of the Mpemba effect apparently depends very strongly on the specific experimental circumstances, and is much harder to reproduce than the original paper would imply. A number of physicists seem skeptical that the effect truly exists at all!
With this in mind, however, it is worth noting that Mpemba’s observation was in fact noted earlier by others over the course of the past two thousand years. Around 350 B.C.E., Aristotle, in giving an explanation of hail in his book “Meteorology”¹, noted:
The fact that the water has previously been warmed contributes to its freezing quickly; for so it cools sooner. (Hence many people, when they want to cool water quickly, begin by putting it in the sun. So the inhabitants of Pontus when they encamp on the ice to fish (they cut a hole in the ice and then fish) pour warm water round their rods that it may freeze the quicker; for they use the ice like lead to fix the rods.) Now it is in hot countries and seasons that the water which forms soon grows warm.
Others who argued for the existence of a Mpemba effect, under some circumstances, include Roger Bacon in the 13th century, and Francis Bacon and René Descartes in the 17th century. It was Mpemba and Osborne, however, who brought it to the attention of modern science.
Before delving into some of the explanations for the effect, it is important to explain why the natural objection to its existence is not necessarily applicable. A natural argument is as follows. “Suppose we have two equal glasses of water, one at 100 °C and one at 30 °C. In order for the water at 100 °C to freeze, it must first cool to 30 °C. The time it takes to freeze is therefore the amount of time it takes to go from 100 to 30 plus the time it takes to go from 30 to zero. It therefore must take longer to freeze than the 30 °C water.”
The flaw in this argument is assuming that a body of water is only characterized by a single parameter: its temperature. In general, there are other characteristics of the water that could be changed due to its heating; for instance, the amount of gas in solution, the presence of other solutes, the presence of convection currents, gradients of the distribution of temperature in the container. Any, all, or none of these may in fact be the culprit, but it is important to realize that a body of water not in thermal equilibrium may have its behavior characterized by a number of different properties.
A number of hypotheses have been proposed as explanations, some based on the factors mentioned:
1. Convective heat transfer. When a liquid is heated, it can form convection currents that rapidly bring the hot liquid to the surface, where the heat is lost by evaporation:
Osborne noted that this convection will keep the top of the liquid hotter than the bottom, even when the temperature matches an initially cold liquid that doesn’t possess this convection cooling. This results in a faster rate of cooling that could, under the right circumstances, result in Mpemba’s observation.
2. Evaporation. A boiling or very hot liquid will lose some of its mass due to evaporation. With a lower mass, it will cool faster, possibly giving a “boost” to the Mpemba effect. Osborne already noted that evaporation alone could not account for all of the rate of cooling of the hot liquid.
3. Degassing. In a series of experiments in 1988, a Polish research group² reproduced the Mpemba effect and noted that the effect depended strongly on the amount of gas dissolved in the water. When the water was purged of air and carbon dioxide, the time to freeze became proportional to the starting temperature. The researchers suggested that the presence of gas was substantially slowing the rate of cooling, and that the heated water was purged of it.
4. Supercooling. In 1995, German scientist David Auerbach proposed³ that the Mpemba effect could be explained by supercooling, and performed experiments to back up the assertion.
Liquids begin to crystallize into a solid at the freezing point with the help of impurities around which the crystals can nucleate. In the absence of such impurities, the liquid can be cooled below its normal freezing point while remaining a liquid — it is “supercooled”. Auerbach suggests that the cold water will supercool to a lower temperature than the hot water, thus giving the hot water an “edge”. However, the reason that hot water has a higher supercooling temperature is unclear, and possibly related to the earlier noted effects.
5. Distribution of solutes. In 2009, an interesting explanation was proposed4 by J.I. Katz, who suggested that solutes present in the cold water slow the freezing process, as suggested earlier, but also that those solutes get driven from the freezing water into the as-yet unfrozen water, slowing the process further.
Other suggestions have been made, and other experiments have been done5, though no consensus seems to have been reached regarding the origins and generality of the effect. The confusion about the Mpemba effect is curiously reminiscent of the controversy around the “Archimedes death ray” controversy we have discussed earlier — the answer depends on the question being asked. Does hot water always freeze faster than cold? Almost certainly not! Are there some circumstances under which hot water freezes faster than cold? It seems likely, though nobody is sure exactly what those circumstances are. Does a negative result disprove the Mpemba effect, or was the experiment just done under the wrong circumstances? Nobody knows for certain.
The controversy no longer is of concern to Erasto Mpemba, however, who did not become a physicist himself but ended up studying at the College of African Wildlife Management. With his education, he eventually became the Principal Game Officer for the Tanzanian Ministry of Natural Resources and Tourism, working on wildlife management and conservation.
Erasto Mpemba, circa 1997 (source).
Regardless of the mystery, Mpemba’s discovery is a wonderful illustration of many important lessons in science: the significance of experiment over theory, the danger of clinging to preconceived notions, the difficulty in evaluating even seemingly simple real-world physics problems, and the importance of perseverance in the face of unreasoning denial. Furthermore, as far as I know the Mpemba effect is one of the only (if not the only) physical phenomena named after an African researcher! It is a wonderful and frustrating hint of how much intellectual potential lies untapped on the continent.
So what do I think of all the controversy? I’m not quite sure what to think! I’d love to test the Mpemba effect myself at home, but our freezer is packed to capacity6! Any enterprising experimenters out there want to give it a try? Describe your results in the comments!
********************
(Thanks to Blake Stacey for providing one of the references used to write this post!)
¹ Aristotle, “Meteorology”, in The Complete Works of Aristotle (The revised Oxford translation), (J. Barnes, ed., Princeton University Press, 1984).
² Wojciechowski, Owczarek and Bednarz, “Freezing of aqueous solutions containing gases,” Cryst. Res. Technol. 23 (1988), 843-848.
³ D. Auerbach, “Supercooling and the Mpemba effect: When hot water freezes quicker than cold,” Am. J. Phys. 63 (1995), 882-885.
4 J.I. Katz, “When hot water freezes before cold,” Am. J. Phys. 77 (2009), 27-29.
5 Esposito, De Risi and Somma, “Mpemba effect and phase transitions in the adiabatic cooling of water before freezing,” Physica A 387 (2008), 757-763.
6 This is a clear indication of my current marital status. Back in my single days, the only thing you would find in my freezer would have been a pair of frozen pizzas!
E.B. Mpemba, & D.G. Osborne (1969). Cool? Physics Education, 4, 172-175
mwenyewe huyo hapo
King _Of_Everything
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Naunga mkono hoja.
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MPEMBA EFFECT KATIKA HISTORIA
Mwaka 1963, Mwanafunzi wa kidato cha tatu katika shule ya sekondari Magamba(Tanga) aliyeitwa Erasto Batholomeo Mpemba, alifanya ugunduzi ulioishtua dunia ya wanasayansi. Aligundua kuwa kimiminika kilichochemshwa( kama maji ya moto) yanaweza kuganda haraka kuliko kimiminika cha baridi. Inawezekana hata wewe hujui hilo.
Ipo hivi, siku moja alijaribu kuweka maziwa aliyochemsha kwenye jokofu la shule, wakati wanafunzi wengine hawakuchemsha. Aligundua kuwa maziwa yake yaliganda haraka kuliko ya wengine.
Alijaribu kumshirikisha mwalimu wake wa fizikia lakini hakupata jibu zuri, kila alipowaeleza wanafunzi wengine walikataa.
Alichaguliwa shule sekondari Mkwawa, hapo alikutana na Profesa wa fizikia ambaye alikuwa pia anafundisha University College-Dar Es Salaam(Sasa ni UDSM). Siku moja Mpemba alikwenda maabara na kujaribu kupasha maji na kisha kuyaweka katika jokofu, pia aliweka na maji ya baridi matokeo yalikuwa ni yaleyale.
Mpemba alimueleza Prof. Denis Osborne ambaye pia alikataa, kwani nadharia ya Isaac Newton inapinga hilo (Newton’s Law of Cooling)
Lakini Prof Osborne alirudi UDSM na kuwashirikisha wanataaluma wengine, walipata matokeo ambayo Mpemba aliyoyasema.
Utafiti huu ulipewa jina ‘Mpemba Effect’, Ulitambuliwa na jarida la Physics Education mwaka 1969, ukiwa kichwa cha habari "Cool?" pia baadae ulirudiwa kwenye jarida la Journal Scientific na kupewa kichwa cha habari "Cool?" yaani "poa".
Ugunduzi huu umepewa hadhi sawa na zile za wanasayansi maarufu kama Roger Bacon, Francis Bacon na René Descartes. Mwaka 2012, Chuo kikuu cha Cambridge kilianzisha shindano la wanasayansi wanaochipukia kuelezea ‘Mpemba Effect’, zaidi ya vijana 22000 walijitokeza.
Ilikubaliwa kuwa ‘Mpemba effect’ iwe "Maji ya moto yaliyochemshwa yanawahi kuganda kuliko maji ya baridi".
Kwa sasa Erasto Mpemba ni afisa wanyama pori na muajiriwa wa wizara ya maliasili na utalii, alisoma chuo cha College of African Wildlife Management, Mwika. Sijui ni kwanini lakini Mpemba sio mwanafizikia ingawa anaheshimika kwa ugunduzi wake katika fizikia akiwa na miaka 13 tu.
Katika Historia.
Mwaka 1963, Mwanafunzi wa kidato cha tatu katika shule ya sekondari Magamba(Tanga) aliyeitwa Erasto Batholomeo Mpemba, alifanya ugunduzi ulioishtua dunia ya wanasayansi. Aligundua kuwa kimiminika kilichochemshwa( kama maji ya moto) yanaweza kuganda haraka kuliko kimiminika cha baridi. Inawezekana hata wewe hujui hilo.
Ipo hivi, siku moja alijaribu kuweka maziwa aliyochemsha kwenye jokofu la shule, wakati wanafunzi wengine hawakuchemsha. Aligundua kuwa maziwa yake yaliganda haraka kuliko ya wengine.
Alijaribu kumshirikisha mwalimu wake wa fizikia lakini hakupata jibu zuri, kila alipowaeleza wanafunzi wengine walikataa.
Alichaguliwa shule sekondari Mkwawa, hapo alikutana na Profesa wa fizikia ambaye alikuwa pia anafundisha University College-Dar Es Salaam(Sasa ni UDSM). Siku moja Mpemba alikwenda maabara na kujaribu kupasha maji na kisha kuyaweka katika jokofu, pia aliweka na maji ya baridi matokeo yalikuwa ni yaleyale.
Mpemba alimueleza Prof. Denis Osborne ambaye pia alikataa, kwani nadharia ya Isaac Newton inapinga hilo (Newton’s Law of Cooling)
Lakini Prof Osborne alirudi UDSM na kuwashirikisha wanataaluma wengine, walipata matokeo ambayo Mpemba aliyoyasema.
Utafiti huu ulipewa jina ‘Mpemba Effect’, Ulitambuliwa na jarida la Physics Education mwaka 1969, ukiwa kichwa cha habari "Cool?" pia baadae ulirudiwa kwenye jarida la Journal Scientific na kupewa kichwa cha habari "Cool?" yaani "poa".
Ugunduzi huu umepewa hadhi sawa na zile za wanasayansi maarufu kama Roger Bacon, Francis Bacon na René Descartes. Mwaka 2012, Chuo kikuu cha Cambridge kilianzisha shindano la wanasayansi wanaochipukia kuelezea ‘Mpemba Effect’, zaidi ya vijana 22000 walijitokeza.
Ilikubaliwa kuwa ‘Mpemba effect’ iwe "Maji ya moto yaliyochemshwa yanawahi kuganda kuliko maji ya baridi".
Kwa sasa Erasto Mpemba ni afisa wanyama pori na muajiriwa wa wizara ya maliasili na utalii, alisoma chuo cha College of African Wildlife Management, Mwika. Sijui ni kwanini lakini Mpemba sio mwanafizikia ingawa anaheshimika kwa ugunduzi wake katika fizikia akiwa na miaka 13 tu.
Katika Historia.
Mpemba Mimi
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Dah - Nilidhani ni "MPEMBA MIMI".
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Huu ugunduzi inaonekana tayari ulikuwa ushafanywa na Aristotle miaka mingi, yeye aliita hali ya namna hiyo ni Antiperistasis!
Ze Heby
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Antiperistasis is a general term for various processes, real or contrived, in which one quality heightens the force of another, opposing, quality.
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FAHARI YETU
“MPEMBA EFFECT”: UDADISI, UTAFITI NA UGUNDUZI WA KITANZANIA
“MAJI ya moto yaliyochemka yanaganda (kuwa barafu) haraka zaidi kabla ya maji ya baridi”.
Ni ugunduzi wa kisayansi wa Mtanzania usiotajwa kwenye Vitabuni, Shuleni wala Vyuoni mwetu hapa nchini, lakini ni gumzo la kitaaluma katika Vyuo na taasisi mbalimbali za elimu za Mataifa mbalimbali. Ni “Udhani” (Hypothesis) unaoumiza vichwa vya wanasayansi wa Dunia yote, kuanzia Ulaya Magharibi, Amerika mpaka Asia.
Ugunduzi huu wa kisayansi unaeoelezea “sifa ya kipekee ya maji” ulifanywa na mwanafunzi wa kidato cha tatu wa Kitanzania katika shule ya sekondari Magamba, Lushoto, Mkoani Tanga, mwaka 1963. Jina la Mwanafunzi huyo ni Erasto Bartholomeo Mpemba, jina ambalo sifa hiyo ya maji (physical phenomenon) imepewa, yaani “Mpemba effect”.
Erasto Batholomeo Mpemba, kama ilivyokuwa kwa wanasayansi wengine maarufu duniani, alifanikiwa kugundua sifa hii muhimu ya maji kama ajali tu (accidental discovery), kama ilivyokuwa kwa Wagunduzi wengine wa Kisayansi wa Kaliba yake, Mfano Friedrich August Kekule (Mgunduzi wa Udhani wa Umbo la Kekule katika Sayansi ya Kemia), Isaack Newton, Archemedes na wengineo, Mpemba naye amefanya ugunduzi wake baada ya tukio la kawaida tu katika maisha yake ambalo lilileta majibu yasiyo ya kawaida na yanayofikirisha.
Katika andiko mashuhuri juu ya “Mpemba Effect” lililochapishwa katika Jarida la Kitaaluma la ‘Journal of Physics Education’ la mwaka 1969, Mpemba anaanza kujieleza ifuatavyo, “Jina langu ni Erasto B. Mpemba, nitawaambia ugunduzi wangu ambao umetokana na matumizi mabaya ya jokofu”.
Masimulizi hayo ya Mpemba katika andiko hilo yanaainisha kwa undani mazingira ya elimu ya Tanzania tokea miaka ile ya mwanzo mwa Taifa letu mpaka sasa. Kikawaida wanafunzi wengi wa kitanzania wanaosema kwenye shule za umma, ama hufanya biashara za walimu wakiwa madarasani wakati wa vipindi au baada ya vipindi, au hufanya biashara za Wazazi wao. Erasto Mpemba na wenzake kadhaa pale shuleni Magamba (Hivi sasa ni Sebastian Kolowa Memorial University, SEKOMU), walikuwa wanauza ‘ice-cream’ baada ya kumaliza vipindi vya masomo.
Ingawa haijawekwa wazi kwenye masimulizi hayo kwamba, mradi huu ulikuwa wa shule ama wa mwalimu tu, lakini wanafunzi waliohusika na biashara hii walikuwa wengi, hivyo iliwabidi wagombee nafasi kwenye jokofu wakati wa kutengeneza ‘ice cream’ hizo. Kwa kawaida ilikuwa wananunua maziwa asubuhi na mapema kutoka vijiji vya jirani kama vile Maina, Mazinde Juu, Mabughai, Kost na kwengineo; wanayachemsha, wanaacha yapoe kisha wanayaweka kwenye jokofu kabla ya kwenda darasani.
Wakimaliza vipindi vyao madarasani, huchukuwa ‘ice-cream’ zao zilizoganda na kupeleka Lushoto-mjini kwa mauzo. Yule atakayekuwa kakosa nafasi ya kuweka ‘ice cream’ zake kwenye jokofu itampasa asubiri mpaka wenzake watoe ice-cream zao nyakati za mchana kwenda kwenye mauzo ndipo na yeye apate nafasi ya kuweka za kwake. Lakini pia kwa yule aliyeweka mwanzo kabla ya mwenzake, alikuwa na uhakika wa kuanza kupeleka ‘ice-cream’ zake sokoni kabla ya mwezake, maana anayeweka mwanzo ice cream zake zitaganda mapema zaidi kabla ya wengine. Hivyo kulikuwa na changamoto mbili muhimu kwa Mpemba na wenzake, kupata nafasi ya kuweka ‘ice cream’ kwenye jokofu, na kuweka mapema zaidi.
Siku moja wakati Mpemba anachemsha maziwa ya ice-cream, mwenzake (mshindani wake kwenye biashara ya ice-cream) aliamua asichemshe maziwa yake ya kutengenezea ice-cream ili awahi nafasi anayoipenda kwenye jokofu kabla Mpemba hajaweka kwenye nafasi yake hiyo. Kwa akili zake za kitoto hakujali afya za walaji, bali cha muhimu kwake ilikuwa awahi nafasi ndani ya jokofu. Mpemba aliendelea kuchemsha maziwa yake, lakini kwa bahati nzuri au mbaya ikawa imebaki nafasi moja tu kwenye jokofu, hivyo naye kwa hofu ya kupoteza hiyo nafasi moja iliyobaki kwenye jokofu akaamua asisubiri mpaka maziwa yapoe ndipo ayaweke jokofuni bali akayewaka hivyo hivyo yakiwa ya moto bado. Japo alijua ni matumizi mabaya ya jokofu, lakini aliamua kufanya hivyo. Anasimuliwa mwenyewe kwenye “andiko” hilo.
Baada ya saa moja na nusu hivi, wakiwa kwenye mapumziko ya vipindi vya darasani, Mpemba na mwenzake waliamua kwenda kwenye jokofu kuangalia hali ya bidhaa zao na pia usalama wa jokofu. Zaidi Mpemba alikuwa na wasiwasi kwa vile aliweka maziwa ya moto kwenye jokofu, hivyo alitaka kwenda kuhakiki usalama wa jokofu. Walichokiona ndicho ambacho leo hii kinajulikana kama “Mpemba effect”, Maziwa ya Mpemba ambayo aliyaweka kwenye jokofu yakiwa ya moto yalishaganda na kuwa ‘ice-cream’, haliyakuwa maziwa ya yule mwenzake aliyeweka mwanzoni zaidi ‘Maziwa ya baridi bila ya kuyachemsha’, yakiwa bado yangali tepe tepe (hayajaganda kuwa ice-cream).
Hali hii ilipekea sintofahamu kubwa kati yao, kwani yule mwanafunzi mwenzake hakuamini kilichokuwa kinatukia bali alimshutumu Mpemba kwamba huenda amechanganya hizo ‘sahani maalum’ walizokuwa wanazitumia kuwekea ‘ice-cream’ zao, Yaani akimaanisha kuwa zile anazodai Mpemba ni ‘ice cream’ zake (zile zilizoganda) sio za kwake, maana haiwezekani kikawaida zigande kabla ya zile za mwenzie aliyeziweka mapema zaidi na zikiwa zenye ubaridi. Mpemba naye hakuafiki hilo, kwa maana alikuwa na yakini na alichokiona, hakueleza waliumaliza vipi ubishani wao lakini kwa dhahiri ni tukio ambalo lilifungua ukurasa mpya katika maisha yake.
Siku kadhaa baada ya tukio hilo, Mpemba akiwa darasani aliamua kumuuliza mwalimu wake wa kidato cha 3 wa somo la Fizikia juu ya alichokishuhudia, lakini majibu ya mwalimu huyu yalimfanya abadili mawazo kwa muda. Kiufupi majibu ya mwalimu huyo yalikuwa sawa na ya yule rafiki yake Mpemba kuwa “Mpemba, Umechanganya sahani za kuhifadhia za ice-cream, hilo jambo haliwezi kutokea.”
Baada ya kumaliza kidato cha nne pale shuleni Magamba, Mpemba alijiunga na kidato cha tano katika shule ya sekondari Mkwawa, Iringa (sasa ni tawi la chuo kikuu cha Dar es salaam, MUCE), akichukua masomo ya sayansi. Siku moja wakiwa katika somo la Fizikia wanasomeshwa mada ya Joto (heat) wakati mwalimu anaielezea “Newton’s law of cooling” (kanuni ya upoaji ya bwana Newton), Mpemba alimuuliza mwalimu wake wa somo hilo wa kidato cha tano swali lile lile ambalo aliliuliza akiwa kidato cha tatu, “kwanini maziwa ya moto yanaganda haraka zaidi kuliko maziwa ya baridi?”
Mpemba alijikuta akiuliza swali hilo kwa sababu maalum, kwa kifupi kanuni hiyo ya bwana mkubwa Newton inaelekeza kwamba, kitu chenye joto-ridi linalokaribiana au kuwa na tofauti ndogo na joto-ridi la mazingira yake basi kitapoa haraka zaidi kuliko kile chenye joto-ridi kubwa sana zaidi ya joto-ridi la mazingira yake. Hii ndiyo kusema kwa mujibu wa kanuni hii ya Newton, Maziwa ya baridi yalitakiwa yagande haraka kwenye jokofu kuliko maziwa ya moto. Jambo ambalo Mpemba aliona ni tofauti na kilichotokea kwenye ‘ice cream’ zake.
Swali lake hili kwa mara nyengine likaibua sintofahamu na mabishano kati ya Mpemba kwa upande mmoja na Mwalimu na wanafunzi wenzie kwa upande wa pili. Mwalimu akisistiza kuwa jambo hilo haliwezekani kisayansi huku Mpemba naye akijenga hoja kuwa japo hakuna hayo maelezo ya Kisayansi lakini yeye amelishuhudia hilo likitokea kwa macho yake mwenyewe, wanafunzi wenzie hawakumuamini kabisa.
Pamoja na ushuhuda wake kukataliwa na wanafunzi pamoja na mwalimu wake lakini bado Mpemba alisimamia alichokiona, yeye aliamini si kila matokeo yalipaswa kwenda sabamba na hali iliyozoeleka na alitaka wenzie wajipe nafasi ya kukubali matokeo mapya tofauti na yale waliyoyazoea. Mwalimu wake baada ya kuchoshwa na Udadisi wake aliamua kuufunga mjadala huo wa kitaaluma kwa kebehi kuwa “hiyo (ya maziwa ya moto kuganda mapema zaidi ya maziwa ya baridi kwenye jokofu) itakuwa ni ‘Fizikia ya Mpemba’ na sio Fizikia ya Ulimwengu”.
Baada ya hapo ikawa ndio utani tena, kila alichokikosea shuleni pale kiliitwa ‘Cha Mpemba’, kwa mfano kwenye hesabu za“Alogarithims” alipokosea basi, mwalimu wa somo hilo na hata wanafunzi wenzie wangelisema hizo (alizokosea) ni ‘hesabu za Mpemba’ na sio hesabu za Algorithms! Lakini Mpemba, hakukatishwa tamaa na hali hiyo.
Siku moja akiwa katika Maabara ya Baiolojia shuleni hapo, aliamua kurudia jaribio lake, lakini badala ya kutumia maziwa mara hii alitumia maji, alijaza kiasi cha maji ujazo sawa kwenye “bikari” (Bilauri ndogo maalum zitumikazo maabara) mbili, moja akaweka maji ya baridi na nyengine akaweka maji ya moto, kisha akaziweka bikari mbili zile kwenye jokofu kwa muda wa saa moja.
Alipokuja kuziangalia baada ya hiyo saa moja alikuta bikari iliyokuwa na maji ya moto tayari imeshaanza kufanya barafu nyingi sana, wakati ile iliyokuwa na maji ya baridi ingali na maji na barafu kidogo! Hii ilizidi kumpa uhakika wa ugunduzi wake, ugunduzi uliokataliwa na waalimu wake wawili wa somo la Fizikia pamoja na wanafunzi wenzie.
Wakati mmoja wanafunzi wa kidato cha tano na sita shuleni Mkwawa walipata nafasi ya kutembelewa na Mhadhiri mwandamimizi kutoka Chuo Kikuu cha Dar es Salaam, Dk. Denis Osborne (wakati huo akiwa bado ni Daktari wa falsafa tu, sasa Profesa Osborne) ambaye alikuwa ni mtaalamu wa Fizikia. Osborne alialikwa shuleni pale na Mkuu wa shule hiyo ili aje kuwahamasisha wanafunzi wa shule hiyo kusoma kwa bidii ili wafaulu na wafanikiwe kujiunga na masomo ya Chuo kikuu.
Lakini akiwa ni mtaalamu wa Fizikia alizungumza kidogo kuhusu somo hilo, mwishoni Wanafunzi walipewa nafasi ya kumuuliza Dk. Osborne maswali mbalimbali mara baada kumaliza mazungumzo yake. Maswali yalikuwa mengi, yapo yaliyohusu namna ya kujiunga na chuo kikuu, idadi ya wanaotakiwa kuingia chuo kikuu, ugumu na wa somo la Fizikia chuo kikuu, unakuwa nani ukimaliza Sahahada ya Fizikia?, n.k. Lakini swali lilowavunja mbavu kwa kicheko wanafunzi wengi kama si wote, hata kupelekea wengine kuona aibu, ni swali alilouliza Erasto Mpemba.
Mpemba alimuuliza Dk. Osborne swali lile lile alilowahi kuwauliza mwanzoni walimu wake wawili wa Fizikia, tofauti ikiwa mara hii akiuliza kuhusu maji na siyo maziwa, na akiwa makini zaidi kujua joto-ridi la awali la maji yake, alimuuliza “Inakuaje ukijaza maji ya moto yenye nyuzi joto 100 za sentigredi na maji baridi yenye nyuzi joto 35 za sentigredi, kwa ujazo sawa kwenye ‘beaker’ mbili tofauti kisha ukaweka kwenye jokofu, maji yaliyokuwa na nyuzi joto 100 za sentigredi yanaganda kabla ya yale yaliyokuwa na nyuzi joto 35 za sentigredi?”
Dk. Osborne, kwanza alicheka kama walivyocheka wengine katika hadhara ile, kisha akamwambia Mpemba arudie swali lake. Mpemba akarudia kile kile alichokiuliza mara ya kwanza, Mara hii uzingatiaji wa Dk. Osborne ulikuwa mkubwa zaidi, mara baada ya Mpemba kurudia swali lake akamuuliza “una hakika umefanya hivyo?”
Mpemba akajibu ndio, nna hakika nimefanya, hapa Prof. Osborne alionesha utofauti wa hali ya juu katika kuiendea kesi hii! Kwanza alitaka kujiridhisha kama kweli alichosikia ndicho kilichoulizwa, pili alitaka kujua imani ya muuliza swali juu ya anachokiuliza (uhakika wake), na tatu na muhimu sana katika taaluma yoyote, alitaka kujua chanzo cha hoja, ndo maana akamuuliza (je ni kweli umefanya wewe mwenyewe?). Baada ya kujiridhisha na yote hayo alijibu swali la Mpemba kwa kumwambia kuwa “Sijui kwa kweli, lakini nakuahidi kuwa nitajaribu huo uchunguzi nikifika Dar es Salaam”.
Kinachofurahisha zaidi kutoka kwa Dk. Osborne sio namna alivyolisikiliza swali kwa umakini mkubwa, bali ni ile hali ya kuwa tayari kusikia na kupokea kitu kipya kutoka hata kwa mwanafunzi wa sekondari ya Kijijini Mkwawa. Jiulize ni maDokta, maProfesa au Walimu vyuoni, mashuleni na kwenye vituo vyetu vya utafiti walio tayari kupokea wazo jipya (ambalo halijatoka kwa wanasyansi wa nje) kutoka kwa wanafunzi wao au hata wafanyakazi wenzao waliochini yao kielimu? Ni wachache sana!
Wanafunzi wenzake, hasa wale wanaojiita vipanga, hawakufurahishwa na kitendo chake cha kuuliza swali ambalo wao waliliona ni la kipuuzi, walifikia hatua hata ya kumhoji “Hivi Mpemba umeelewa kweli ‘sura nzima’ ya kitabu inayoelezea Newtons law of cooling?” Lakini Mpemba siku zote alipenda kuwajibu kuwa “Nadharia wakati mwengine hutofautiana na majibu ya uchuguzi kwa vitendo”.
Dk. Osborne aliporudi Dar es salaam aliurudia ule uchunguzi, kwa kuweka maji ya moto na baridi kwenye ‘bikari’ mbili tofauti (ujazo sawa kama Mpemba), kisha akaziweka bilauri zile kwenye jokofu kwa muda wa saa moja. Majibu aliyopata ni kama yale aliyoyapata Mpemba kule Magamba na hatimaye pale Iringa. Kwa kutumia ufahamu wake kwenye sayansi (Fizikia), alijaribu kuelezea, sababu zinazoweza kupelekea hali hiyo, na hatimaye mwaka 1969, walichapisha chapisho lao (scientific paper) kwenye Jarida la ‘Journal of Physics Education’ lenye kichwa cha habari (Title), “Cool?” (Poa?).
Chapisho hilo ni moja ya Maandiko machache ya Kisayansi ambayo yameandikwa katika mtindo wa Masimulizi. Ni simulizi ya kweli katika ulimwengu wa sayansi na ugunduzi, Simulizi inayobeba mambo mengi na inayoonesha uhalisia wa mfumo mbovu wa elimu yetu. Maana hata baada ya kumaliza kidato sita, Mpemba alipotea kabisa katika ulimwengu wa sayansi na aliishia kusoma “Chuo cha uhifadhi Wanyamapori” badala ya kuwa Mwanasayansi.
Ni simulizi inayoonyesha kuwa pamoja na ukatishwaji tamaa mkubwa unaofanywa kwa wanafunzi mashuleni lakini pia hakuna juhudi zozote zinazofanywa kuviendeleza vipaji mbalimbali vinachomozwa na kuushinda mtihani huo wa kukatishwa tamaa. Kutokana na masimulizi haya tunaonyeshwa kuwa “Udhani” hata kama umeasisiwa na wanasayansi wakubwa wa kimagharibi na Amerika, bado unaweza kuwa na mapungufu katika kulielezea jambo husika, hivyo bado kuna nafasi ya kuzifanyia marekebisho na hata kuzipinga tafiti mbalimbali zilizowahi kufanywa.
Pia simulizi hii imetuonesha tofauti ya kuwa na wasomi ambao ni “wadadisi” na wale ambao ni wasomi “wahafidhina” wanaoendesha taaluma zao kiimla na kimazoea. Zaidi ya yote hii ni simulizi inayotufunza kuwa “Hakuna swali la kipuuzi”.
Chakusikitisha zaidi, ambacho ndicho kilichonisukuma kuandika makala hii, ni jinsi utafiti huu wa kujivunia, na wa kipekee, uliofanywa na wataaalam wetu ndani ya ardhi yetu, hautajwi wala kusimuliwa popote nchini, si katika shule wala vyuo vyetu. Baadhi ya vyanzo vya Kitafiti duniani vimeainisha kwamba “Mpemba effect” ni moja kati ya ‘Falsafa chache za Kifizikia’ (kama sio pekee tu) iliyopewa jina la mtafiti wa kiafrika.
Ajabu, hapa Tanzania tumeshindwa hata kumweka Mpemba kwenye vitabu vya hadithi vya shule za Msingi ili watoto wetu wajifunze, wahamasike na waamini kwamba inawezekana kuwa mwanasayansi mgunduzi hata bila kufika Chuo Kikuu. Hilo lingefanyika lingewapa fursa wanafunzi hawa ya kujifunza kujiamini na kutokata tamaa juu ya kile wanachokiamini au kukijua. Zaidi wangejifunza mbinu za kuhimili changamoto, wangetambua kwamba katika kila hatua ya maendeleo viko vizingiti vya kukatisha tamaa, na hivyo wangejifunza namna ya kuenenda katika nyakati hizo.
Kwa kuona umuhimu mkubwa wa “Mpemba effect” katika ulimwengu huu wa Sayansi na Teknolojia, Mwaka 2012 tu, Jarida ya ‘The Royal Society of Chemistry’ la Chuo Kikuu cha Cambridge cha Uingereza, ambalo ni moja ya Majarida Makongwe sana na yenye hadhi ya juu ya Kitaaluma duniani lilitangaza zawadi nono ya pesa kwa mtu au kikundi cha wanasayansi watakaoweza kutoa maelezo mazuri, bora na ya kujenga zaidi kuhusu “dhana” kwamba maji ya moto yanaganda mapema zaidi kabla ya maji ya baridi - “Mpemba effect”.
Watu zaidi ya ishirini na mbili elfu (22,000) walijitokeza, Kisha 11 wakaingia fainali, na hatimaye Nikola Bregovic kutoka Croatia ambaye ni mfanyakazi wa Maabara ya Kemia katika Chuo Kikuu cha Zagreb, akatangazwa kuwa mshindi. Januari 10, 2013 Mtanzania Erasto Bartholomeo Mpemba ndiye aliyepewa heshima kubwa ya kumtangaza mshindi na kumpa zawadi hiyo kwa niaba ya Jaribu la ‘The Royal Society of Chemistry’, tukio ambalo lilichochea hamasa juu ya Udadisi, Utafiti na Ugunduzi kwa vijana wengi wa Ulaya.
“Mpemba effect” iko bado na inaishi kwenye maabara mbalimbali duniani, kuanzia Ulaya, Amerika na Asia, lakini sio Tanzania. Tafiti mbali mbali zimeshafanywa (Katz, 2009, Esposito, 2008, na Auerbach, 1995), na bado zinaendelea kufanywa ili kutafuta sababu za msingi za “dhana” hii ili mwishowe iweze kuwekwa katika matumizi sahihi kama kanuni (law) kwa ajili ya maendeleo ya wanaadam.
Pichani ni Erasto B Mpemba akiwa pamoja na Profesa Denis Osborne katika moja ya Mikutano mbalimbali waliyohudhuria pamoja duniani. Picha na Maelezo haya ni kwa hisani kubwa ya Ndugu Ally Mahadhy, Mwanafunzi wa Kitanzania wa Shahada ya Uzamivu katika Chuo Kikuu cha Lund, Sweden.
Kwa Habari zaidi juu ya Nguli wa Kitanzania walio FAHARI YETU LIKE Ukurasa wetu wa WATANZANIA MASHUHURI ili upate kujifunza zaidi
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“MPEMBA EFFECT”: UDADISI, UTAFITI NA UGUNDUZI WA KITANZANIA
“MAJI ya moto yaliyochemka yanaganda (kuwa barafu) haraka zaidi kabla ya maji ya baridi”.
Ni ugunduzi wa kisayansi wa Mtanzania usiotajwa kwenye Vitabuni, Shuleni wala Vyuoni mwetu hapa nchini, lakini ni gumzo la kitaaluma katika Vyuo na taasisi mbalimbali za elimu za Mataifa mbalimbali. Ni “Udhani” (Hypothesis) unaoumiza vichwa vya wanasayansi wa Dunia yote, kuanzia Ulaya Magharibi, Amerika mpaka Asia.
Ugunduzi huu wa kisayansi unaeoelezea “sifa ya kipekee ya maji” ulifanywa na mwanafunzi wa kidato cha tatu wa Kitanzania katika shule ya sekondari Magamba, Lushoto, Mkoani Tanga, mwaka 1963. Jina la Mwanafunzi huyo ni Erasto Bartholomeo Mpemba, jina ambalo sifa hiyo ya maji (physical phenomenon) imepewa, yaani “Mpemba effect”.
Erasto Batholomeo Mpemba, kama ilivyokuwa kwa wanasayansi wengine maarufu duniani, alifanikiwa kugundua sifa hii muhimu ya maji kama ajali tu (accidental discovery), kama ilivyokuwa kwa Wagunduzi wengine wa Kisayansi wa Kaliba yake, Mfano Friedrich August Kekule (Mgunduzi wa Udhani wa Umbo la Kekule katika Sayansi ya Kemia), Isaack Newton, Archemedes na wengineo, Mpemba naye amefanya ugunduzi wake baada ya tukio la kawaida tu katika maisha yake ambalo lilileta majibu yasiyo ya kawaida na yanayofikirisha.
Katika andiko mashuhuri juu ya “Mpemba Effect” lililochapishwa katika Jarida la Kitaaluma la ‘Journal of Physics Education’ la mwaka 1969, Mpemba anaanza kujieleza ifuatavyo, “Jina langu ni Erasto B. Mpemba, nitawaambia ugunduzi wangu ambao umetokana na matumizi mabaya ya jokofu”.
Masimulizi hayo ya Mpemba katika andiko hilo yanaainisha kwa undani mazingira ya elimu ya Tanzania tokea miaka ile ya mwanzo mwa Taifa letu mpaka sasa. Kikawaida wanafunzi wengi wa kitanzania wanaosema kwenye shule za umma, ama hufanya biashara za walimu wakiwa madarasani wakati wa vipindi au baada ya vipindi, au hufanya biashara za Wazazi wao. Erasto Mpemba na wenzake kadhaa pale shuleni Magamba (Hivi sasa ni Sebastian Kolowa Memorial University, SEKOMU), walikuwa wanauza ‘ice-cream’ baada ya kumaliza vipindi vya masomo.
Ingawa haijawekwa wazi kwenye masimulizi hayo kwamba, mradi huu ulikuwa wa shule ama wa mwalimu tu, lakini wanafunzi waliohusika na biashara hii walikuwa wengi, hivyo iliwabidi wagombee nafasi kwenye jokofu wakati wa kutengeneza ‘ice cream’ hizo. Kwa kawaida ilikuwa wananunua maziwa asubuhi na mapema kutoka vijiji vya jirani kama vile Maina, Mazinde Juu, Mabughai, Kost na kwengineo; wanayachemsha, wanaacha yapoe kisha wanayaweka kwenye jokofu kabla ya kwenda darasani.
Wakimaliza vipindi vyao madarasani, huchukuwa ‘ice-cream’ zao zilizoganda na kupeleka Lushoto-mjini kwa mauzo. Yule atakayekuwa kakosa nafasi ya kuweka ‘ice cream’ zake kwenye jokofu itampasa asubiri mpaka wenzake watoe ice-cream zao nyakati za mchana kwenda kwenye mauzo ndipo na yeye apate nafasi ya kuweka za kwake. Lakini pia kwa yule aliyeweka mwanzo kabla ya mwenzake, alikuwa na uhakika wa kuanza kupeleka ‘ice-cream’ zake sokoni kabla ya mwezake, maana anayeweka mwanzo ice cream zake zitaganda mapema zaidi kabla ya wengine. Hivyo kulikuwa na changamoto mbili muhimu kwa Mpemba na wenzake, kupata nafasi ya kuweka ‘ice cream’ kwenye jokofu, na kuweka mapema zaidi.
Siku moja wakati Mpemba anachemsha maziwa ya ice-cream, mwenzake (mshindani wake kwenye biashara ya ice-cream) aliamua asichemshe maziwa yake ya kutengenezea ice-cream ili awahi nafasi anayoipenda kwenye jokofu kabla Mpemba hajaweka kwenye nafasi yake hiyo. Kwa akili zake za kitoto hakujali afya za walaji, bali cha muhimu kwake ilikuwa awahi nafasi ndani ya jokofu. Mpemba aliendelea kuchemsha maziwa yake, lakini kwa bahati nzuri au mbaya ikawa imebaki nafasi moja tu kwenye jokofu, hivyo naye kwa hofu ya kupoteza hiyo nafasi moja iliyobaki kwenye jokofu akaamua asisubiri mpaka maziwa yapoe ndipo ayaweke jokofuni bali akayewaka hivyo hivyo yakiwa ya moto bado. Japo alijua ni matumizi mabaya ya jokofu, lakini aliamua kufanya hivyo. Anasimuliwa mwenyewe kwenye “andiko” hilo.
Baada ya saa moja na nusu hivi, wakiwa kwenye mapumziko ya vipindi vya darasani, Mpemba na mwenzake waliamua kwenda kwenye jokofu kuangalia hali ya bidhaa zao na pia usalama wa jokofu. Zaidi Mpemba alikuwa na wasiwasi kwa vile aliweka maziwa ya moto kwenye jokofu, hivyo alitaka kwenda kuhakiki usalama wa jokofu. Walichokiona ndicho ambacho leo hii kinajulikana kama “Mpemba effect”, Maziwa ya Mpemba ambayo aliyaweka kwenye jokofu yakiwa ya moto yalishaganda na kuwa ‘ice-cream’, haliyakuwa maziwa ya yule mwenzake aliyeweka mwanzoni zaidi ‘Maziwa ya baridi bila ya kuyachemsha’, yakiwa bado yangali tepe tepe (hayajaganda kuwa ice-cream).
Hali hii ilipekea sintofahamu kubwa kati yao, kwani yule mwanafunzi mwenzake hakuamini kilichokuwa kinatukia bali alimshutumu Mpemba kwamba huenda amechanganya hizo ‘sahani maalum’ walizokuwa wanazitumia kuwekea ‘ice-cream’ zao, Yaani akimaanisha kuwa zile anazodai Mpemba ni ‘ice cream’ zake (zile zilizoganda) sio za kwake, maana haiwezekani kikawaida zigande kabla ya zile za mwenzie aliyeziweka mapema zaidi na zikiwa zenye ubaridi. Mpemba naye hakuafiki hilo, kwa maana alikuwa na yakini na alichokiona, hakueleza waliumaliza vipi ubishani wao lakini kwa dhahiri ni tukio ambalo lilifungua ukurasa mpya katika maisha yake.
Siku kadhaa baada ya tukio hilo, Mpemba akiwa darasani aliamua kumuuliza mwalimu wake wa kidato cha 3 wa somo la Fizikia juu ya alichokishuhudia, lakini majibu ya mwalimu huyu yalimfanya abadili mawazo kwa muda. Kiufupi majibu ya mwalimu huyo yalikuwa sawa na ya yule rafiki yake Mpemba kuwa “Mpemba, Umechanganya sahani za kuhifadhia za ice-cream, hilo jambo haliwezi kutokea.”
Baada ya kumaliza kidato cha nne pale shuleni Magamba, Mpemba alijiunga na kidato cha tano katika shule ya sekondari Mkwawa, Iringa (sasa ni tawi la chuo kikuu cha Dar es salaam, MUCE), akichukua masomo ya sayansi. Siku moja wakiwa katika somo la Fizikia wanasomeshwa mada ya Joto (heat) wakati mwalimu anaielezea “Newton’s law of cooling” (kanuni ya upoaji ya bwana Newton), Mpemba alimuuliza mwalimu wake wa somo hilo wa kidato cha tano swali lile lile ambalo aliliuliza akiwa kidato cha tatu, “kwanini maziwa ya moto yanaganda haraka zaidi kuliko maziwa ya baridi?”
Mpemba alijikuta akiuliza swali hilo kwa sababu maalum, kwa kifupi kanuni hiyo ya bwana mkubwa Newton inaelekeza kwamba, kitu chenye joto-ridi linalokaribiana au kuwa na tofauti ndogo na joto-ridi la mazingira yake basi kitapoa haraka zaidi kuliko kile chenye joto-ridi kubwa sana zaidi ya joto-ridi la mazingira yake. Hii ndiyo kusema kwa mujibu wa kanuni hii ya Newton, Maziwa ya baridi yalitakiwa yagande haraka kwenye jokofu kuliko maziwa ya moto. Jambo ambalo Mpemba aliona ni tofauti na kilichotokea kwenye ‘ice cream’ zake.
Swali lake hili kwa mara nyengine likaibua sintofahamu na mabishano kati ya Mpemba kwa upande mmoja na Mwalimu na wanafunzi wenzie kwa upande wa pili. Mwalimu akisistiza kuwa jambo hilo haliwezekani kisayansi huku Mpemba naye akijenga hoja kuwa japo hakuna hayo maelezo ya Kisayansi lakini yeye amelishuhudia hilo likitokea kwa macho yake mwenyewe, wanafunzi wenzie hawakumuamini kabisa.
Pamoja na ushuhuda wake kukataliwa na wanafunzi pamoja na mwalimu wake lakini bado Mpemba alisimamia alichokiona, yeye aliamini si kila matokeo yalipaswa kwenda sabamba na hali iliyozoeleka na alitaka wenzie wajipe nafasi ya kukubali matokeo mapya tofauti na yale waliyoyazoea. Mwalimu wake baada ya kuchoshwa na Udadisi wake aliamua kuufunga mjadala huo wa kitaaluma kwa kebehi kuwa “hiyo (ya maziwa ya moto kuganda mapema zaidi ya maziwa ya baridi kwenye jokofu) itakuwa ni ‘Fizikia ya Mpemba’ na sio Fizikia ya Ulimwengu”.
Baada ya hapo ikawa ndio utani tena, kila alichokikosea shuleni pale kiliitwa ‘Cha Mpemba’, kwa mfano kwenye hesabu za“Alogarithims” alipokosea basi, mwalimu wa somo hilo na hata wanafunzi wenzie wangelisema hizo (alizokosea) ni ‘hesabu za Mpemba’ na sio hesabu za Algorithms! Lakini Mpemba, hakukatishwa tamaa na hali hiyo.
Siku moja akiwa katika Maabara ya Baiolojia shuleni hapo, aliamua kurudia jaribio lake, lakini badala ya kutumia maziwa mara hii alitumia maji, alijaza kiasi cha maji ujazo sawa kwenye “bikari” (Bilauri ndogo maalum zitumikazo maabara) mbili, moja akaweka maji ya baridi na nyengine akaweka maji ya moto, kisha akaziweka bikari mbili zile kwenye jokofu kwa muda wa saa moja.
Alipokuja kuziangalia baada ya hiyo saa moja alikuta bikari iliyokuwa na maji ya moto tayari imeshaanza kufanya barafu nyingi sana, wakati ile iliyokuwa na maji ya baridi ingali na maji na barafu kidogo! Hii ilizidi kumpa uhakika wa ugunduzi wake, ugunduzi uliokataliwa na waalimu wake wawili wa somo la Fizikia pamoja na wanafunzi wenzie.
Wakati mmoja wanafunzi wa kidato cha tano na sita shuleni Mkwawa walipata nafasi ya kutembelewa na Mhadhiri mwandamimizi kutoka Chuo Kikuu cha Dar es Salaam, Dk. Denis Osborne (wakati huo akiwa bado ni Daktari wa falsafa tu, sasa Profesa Osborne) ambaye alikuwa ni mtaalamu wa Fizikia. Osborne alialikwa shuleni pale na Mkuu wa shule hiyo ili aje kuwahamasisha wanafunzi wa shule hiyo kusoma kwa bidii ili wafaulu na wafanikiwe kujiunga na masomo ya Chuo kikuu.
Lakini akiwa ni mtaalamu wa Fizikia alizungumza kidogo kuhusu somo hilo, mwishoni Wanafunzi walipewa nafasi ya kumuuliza Dk. Osborne maswali mbalimbali mara baada kumaliza mazungumzo yake. Maswali yalikuwa mengi, yapo yaliyohusu namna ya kujiunga na chuo kikuu, idadi ya wanaotakiwa kuingia chuo kikuu, ugumu na wa somo la Fizikia chuo kikuu, unakuwa nani ukimaliza Sahahada ya Fizikia?, n.k. Lakini swali lilowavunja mbavu kwa kicheko wanafunzi wengi kama si wote, hata kupelekea wengine kuona aibu, ni swali alilouliza Erasto Mpemba.
Mpemba alimuuliza Dk. Osborne swali lile lile alilowahi kuwauliza mwanzoni walimu wake wawili wa Fizikia, tofauti ikiwa mara hii akiuliza kuhusu maji na siyo maziwa, na akiwa makini zaidi kujua joto-ridi la awali la maji yake, alimuuliza “Inakuaje ukijaza maji ya moto yenye nyuzi joto 100 za sentigredi na maji baridi yenye nyuzi joto 35 za sentigredi, kwa ujazo sawa kwenye ‘beaker’ mbili tofauti kisha ukaweka kwenye jokofu, maji yaliyokuwa na nyuzi joto 100 za sentigredi yanaganda kabla ya yale yaliyokuwa na nyuzi joto 35 za sentigredi?”
Dk. Osborne, kwanza alicheka kama walivyocheka wengine katika hadhara ile, kisha akamwambia Mpemba arudie swali lake. Mpemba akarudia kile kile alichokiuliza mara ya kwanza, Mara hii uzingatiaji wa Dk. Osborne ulikuwa mkubwa zaidi, mara baada ya Mpemba kurudia swali lake akamuuliza “una hakika umefanya hivyo?”
Mpemba akajibu ndio, nna hakika nimefanya, hapa Prof. Osborne alionesha utofauti wa hali ya juu katika kuiendea kesi hii! Kwanza alitaka kujiridhisha kama kweli alichosikia ndicho kilichoulizwa, pili alitaka kujua imani ya muuliza swali juu ya anachokiuliza (uhakika wake), na tatu na muhimu sana katika taaluma yoyote, alitaka kujua chanzo cha hoja, ndo maana akamuuliza (je ni kweli umefanya wewe mwenyewe?). Baada ya kujiridhisha na yote hayo alijibu swali la Mpemba kwa kumwambia kuwa “Sijui kwa kweli, lakini nakuahidi kuwa nitajaribu huo uchunguzi nikifika Dar es Salaam”.
Kinachofurahisha zaidi kutoka kwa Dk. Osborne sio namna alivyolisikiliza swali kwa umakini mkubwa, bali ni ile hali ya kuwa tayari kusikia na kupokea kitu kipya kutoka hata kwa mwanafunzi wa sekondari ya Kijijini Mkwawa. Jiulize ni maDokta, maProfesa au Walimu vyuoni, mashuleni na kwenye vituo vyetu vya utafiti walio tayari kupokea wazo jipya (ambalo halijatoka kwa wanasyansi wa nje) kutoka kwa wanafunzi wao au hata wafanyakazi wenzao waliochini yao kielimu? Ni wachache sana!
Wanafunzi wenzake, hasa wale wanaojiita vipanga, hawakufurahishwa na kitendo chake cha kuuliza swali ambalo wao waliliona ni la kipuuzi, walifikia hatua hata ya kumhoji “Hivi Mpemba umeelewa kweli ‘sura nzima’ ya kitabu inayoelezea Newtons law of cooling?” Lakini Mpemba siku zote alipenda kuwajibu kuwa “Nadharia wakati mwengine hutofautiana na majibu ya uchuguzi kwa vitendo”.
Dk. Osborne aliporudi Dar es salaam aliurudia ule uchunguzi, kwa kuweka maji ya moto na baridi kwenye ‘bikari’ mbili tofauti (ujazo sawa kama Mpemba), kisha akaziweka bilauri zile kwenye jokofu kwa muda wa saa moja. Majibu aliyopata ni kama yale aliyoyapata Mpemba kule Magamba na hatimaye pale Iringa. Kwa kutumia ufahamu wake kwenye sayansi (Fizikia), alijaribu kuelezea, sababu zinazoweza kupelekea hali hiyo, na hatimaye mwaka 1969, walichapisha chapisho lao (scientific paper) kwenye Jarida la ‘Journal of Physics Education’ lenye kichwa cha habari (Title), “Cool?” (Poa?).
Chapisho hilo ni moja ya Maandiko machache ya Kisayansi ambayo yameandikwa katika mtindo wa Masimulizi. Ni simulizi ya kweli katika ulimwengu wa sayansi na ugunduzi, Simulizi inayobeba mambo mengi na inayoonesha uhalisia wa mfumo mbovu wa elimu yetu. Maana hata baada ya kumaliza kidato sita, Mpemba alipotea kabisa katika ulimwengu wa sayansi na aliishia kusoma “Chuo cha uhifadhi Wanyamapori” badala ya kuwa Mwanasayansi.
Ni simulizi inayoonyesha kuwa pamoja na ukatishwaji tamaa mkubwa unaofanywa kwa wanafunzi mashuleni lakini pia hakuna juhudi zozote zinazofanywa kuviendeleza vipaji mbalimbali vinachomozwa na kuushinda mtihani huo wa kukatishwa tamaa. Kutokana na masimulizi haya tunaonyeshwa kuwa “Udhani” hata kama umeasisiwa na wanasayansi wakubwa wa kimagharibi na Amerika, bado unaweza kuwa na mapungufu katika kulielezea jambo husika, hivyo bado kuna nafasi ya kuzifanyia marekebisho na hata kuzipinga tafiti mbalimbali zilizowahi kufanywa.
Pia simulizi hii imetuonesha tofauti ya kuwa na wasomi ambao ni “wadadisi” na wale ambao ni wasomi “wahafidhina” wanaoendesha taaluma zao kiimla na kimazoea. Zaidi ya yote hii ni simulizi inayotufunza kuwa “Hakuna swali la kipuuzi”.
Chakusikitisha zaidi, ambacho ndicho kilichonisukuma kuandika makala hii, ni jinsi utafiti huu wa kujivunia, na wa kipekee, uliofanywa na wataaalam wetu ndani ya ardhi yetu, hautajwi wala kusimuliwa popote nchini, si katika shule wala vyuo vyetu. Baadhi ya vyanzo vya Kitafiti duniani vimeainisha kwamba “Mpemba effect” ni moja kati ya ‘Falsafa chache za Kifizikia’ (kama sio pekee tu) iliyopewa jina la mtafiti wa kiafrika.
Ajabu, hapa Tanzania tumeshindwa hata kumweka Mpemba kwenye vitabu vya hadithi vya shule za Msingi ili watoto wetu wajifunze, wahamasike na waamini kwamba inawezekana kuwa mwanasayansi mgunduzi hata bila kufika Chuo Kikuu. Hilo lingefanyika lingewapa fursa wanafunzi hawa ya kujifunza kujiamini na kutokata tamaa juu ya kile wanachokiamini au kukijua. Zaidi wangejifunza mbinu za kuhimili changamoto, wangetambua kwamba katika kila hatua ya maendeleo viko vizingiti vya kukatisha tamaa, na hivyo wangejifunza namna ya kuenenda katika nyakati hizo.
Kwa kuona umuhimu mkubwa wa “Mpemba effect” katika ulimwengu huu wa Sayansi na Teknolojia, Mwaka 2012 tu, Jarida ya ‘The Royal Society of Chemistry’ la Chuo Kikuu cha Cambridge cha Uingereza, ambalo ni moja ya Majarida Makongwe sana na yenye hadhi ya juu ya Kitaaluma duniani lilitangaza zawadi nono ya pesa kwa mtu au kikundi cha wanasayansi watakaoweza kutoa maelezo mazuri, bora na ya kujenga zaidi kuhusu “dhana” kwamba maji ya moto yanaganda mapema zaidi kabla ya maji ya baridi - “Mpemba effect”.
Watu zaidi ya ishirini na mbili elfu (22,000) walijitokeza, Kisha 11 wakaingia fainali, na hatimaye Nikola Bregovic kutoka Croatia ambaye ni mfanyakazi wa Maabara ya Kemia katika Chuo Kikuu cha Zagreb, akatangazwa kuwa mshindi. Januari 10, 2013 Mtanzania Erasto Bartholomeo Mpemba ndiye aliyepewa heshima kubwa ya kumtangaza mshindi na kumpa zawadi hiyo kwa niaba ya Jaribu la ‘The Royal Society of Chemistry’, tukio ambalo lilichochea hamasa juu ya Udadisi, Utafiti na Ugunduzi kwa vijana wengi wa Ulaya.
“Mpemba effect” iko bado na inaishi kwenye maabara mbalimbali duniani, kuanzia Ulaya, Amerika na Asia, lakini sio Tanzania. Tafiti mbali mbali zimeshafanywa (Katz, 2009, Esposito, 2008, na Auerbach, 1995), na bado zinaendelea kufanywa ili kutafuta sababu za msingi za “dhana” hii ili mwishowe iweze kuwekwa katika matumizi sahihi kama kanuni (law) kwa ajili ya maendeleo ya wanaadam.
Pichani ni Erasto B Mpemba akiwa pamoja na Profesa Denis Osborne katika moja ya Mikutano mbalimbali waliyohudhuria pamoja duniani. Picha na Maelezo haya ni kwa hisani kubwa ya Ndugu Ally Mahadhy, Mwanafunzi wa Kitanzania wa Shahada ya Uzamivu katika Chuo Kikuu cha Lund, Sweden.
Kwa Habari zaidi juu ya Nguli wa Kitanzania walio FAHARI YETU LIKE Ukurasa wetu wa WATANZANIA MASHUHURI ili upate kujifunza zaidi
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Nyankuru Wankuru
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FAHARI YETU
“MPEMBA EFFECT”: UDADISI, UTAFITI NA UGUNDUZI WA KITANZANIA
“MAJI ya moto yaliyochemka yanaganda (kuwa barafu) haraka zaidi kabla ya maji ya baridi”.
Ni ugunduzi wa kisayansi wa Mtanzania usiotajwa kwenye Vitabuni, Shuleni wala Vyuoni mwetu hapa nchini, lakini ni gumzo la kitaaluma katika Vyuo na taasisi mbalimbali za elimu za Mataifa mbalimbali. Ni “Udhani” (Hypothesis) unaoumiza vichwa vya wanasayansi wa Dunia yote, kuanzia Ulaya Magharibi, Amerika mpaka Asia.
Ugunduzi huu wa kisayansi unaeoelezea “sifa ya kipekee ya maji” ulifanywa na mwanafunzi wa kidato cha tatu wa Kitanzania katika shule ya sekondari Magamba, Lushoto, Mkoani Tanga, mwaka 1963. Jina la Mwanafunzi huyo ni Erasto Bartholomeo Mpemba, jina ambalo sifa hiyo ya maji (physical phenomenon) imepewa, yaani “Mpemba effect”.
Erasto Batholomeo Mpemba, kama ilivyokuwa kwa wanasayansi wengine maarufu duniani, alifanikiwa kugundua sifa hii muhimu ya maji kama ajali tu (accidental discovery), kama ilivyokuwa kwa Wagunduzi wengine wa Kisayansi wa Kaliba yake, Mfano Friedrich August Kekule (Mgunduzi wa Udhani wa Umbo la Kekule katika Sayansi ya Kemia), Isaack Newton, Archemedes na wengineo, Mpemba naye amefanya ugunduzi wake baada ya tukio la kawaida tu katika maisha yake ambalo lilileta majibu yasiyo ya kawaida na yanayofikirisha.
Katika andiko mashuhuri juu ya “Mpemba Effect” lililochapishwa katika Jarida la Kitaaluma la ‘Journal of Physics Education’ la mwaka 1969, Mpemba anaanza kujieleza ifuatavyo, “Jina langu ni Erasto B. Mpemba, nitawaambia ugunduzi wangu ambao umetokana na matumizi mabaya ya jokofu”.
Masimulizi hayo ya Mpemba katika andiko hilo yanaainisha kwa undani mazingira ya elimu ya Tanzania tokea miaka ile ya mwanzo mwa Taifa letu mpaka sasa. Kikawaida wanafunzi wengi wa kitanzania wanaosema kwenye shule za umma, ama hufanya biashara za walimu wakiwa madarasani wakati wa vipindi au baada ya vipindi, au hufanya biashara za Wazazi wao. Erasto Mpemba na wenzake kadhaa pale shuleni Magamba (Hivi sasa ni Sebastian Kolowa Memorial University, SEKOMU), walikuwa wanauza ‘ice-cream’ baada ya kumaliza vipindi vya masomo.
Ingawa haijawekwa wazi kwenye masimulizi hayo kwamba, mradi huu ulikuwa wa shule ama wa mwalimu tu, lakini wanafunzi waliohusika na biashara hii walikuwa wengi, hivyo iliwabidi wagombee nafasi kwenye jokofu wakati wa kutengeneza ‘ice cream’ hizo. Kwa kawaida ilikuwa wananunua maziwa asubuhi na mapema kutoka vijiji vya jirani kama vile Maina, Mazinde Juu, Mabughai, Kost na kwengineo; wanayachemsha, wanaacha yapoe kisha wanayaweka kwenye jokofu kabla ya kwenda darasani.
Wakimaliza vipindi vyao madarasani, huchukuwa ‘ice-cream’ zao zilizoganda na kupeleka Lushoto-mjini kwa mauzo. Yule atakayekuwa kakosa nafasi ya kuweka ‘ice cream’ zake kwenye jokofu itampasa asubiri mpaka wenzake watoe ice-cream zao nyakati za mchana kwenda kwenye mauzo ndipo na yeye apate nafasi ya kuweka za kwake. Lakini pia kwa yule aliyeweka mwanzo kabla ya mwenzake, alikuwa na uhakika wa kuanza kupeleka ‘ice-cream’ zake sokoni kabla ya mwezake, maana anayeweka mwanzo ice cream zake zitaganda mapema zaidi kabla ya wengine. Hivyo kulikuwa na changamoto mbili muhimu kwa Mpemba na wenzake, kupata nafasi ya kuweka ‘ice cream’ kwenye jokofu, na kuweka mapema zaidi.
Siku moja wakati Mpemba anachemsha maziwa ya ice-cream, mwenzake (mshindani wake kwenye biashara ya ice-cream) aliamua asichemshe maziwa yake ya kutengenezea ice-cream ili awahi nafasi anayoipenda kwenye jokofu kabla Mpemba hajaweka kwenye nafasi yake hiyo. Kwa akili zake za kitoto hakujali afya za walaji, bali cha muhimu kwake ilikuwa awahi nafasi ndani ya jokofu. Mpemba aliendelea kuchemsha maziwa yake, lakini kwa bahati nzuri au mbaya ikawa imebaki nafasi moja tu kwenye jokofu, hivyo naye kwa hofu ya kupoteza hiyo nafasi moja iliyobaki kwenye jokofu akaamua asisubiri mpaka maziwa yapoe ndipo ayaweke jokofuni bali akayewaka hivyo hivyo yakiwa ya moto bado. Japo alijua ni matumizi mabaya ya jokofu, lakini aliamua kufanya hivyo. Anasimuliwa mwenyewe kwenye “andiko” hilo.
Baada ya saa moja na nusu hivi, wakiwa kwenye mapumziko ya vipindi vya darasani, Mpemba na mwenzake waliamua kwenda kwenye jokofu kuangalia hali ya bidhaa zao na pia usalama wa jokofu. Zaidi Mpemba alikuwa na wasiwasi kwa vile aliweka maziwa ya moto kwenye jokofu, hivyo alitaka kwenda kuhakiki usalama wa jokofu. Walichokiona ndicho ambacho leo hii kinajulikana kama “Mpemba effect”, Maziwa ya Mpemba ambayo aliyaweka kwenye jokofu yakiwa ya moto yalishaganda na kuwa ‘ice-cream’, haliyakuwa maziwa ya yule mwenzake aliyeweka mwanzoni zaidi ‘Maziwa ya baridi bila ya kuyachemsha’, yakiwa bado yangali tepe tepe (hayajaganda kuwa ice-cream).
Hali hii ilipekea sintofahamu kubwa kati yao, kwani yule mwanafunzi mwenzake hakuamini kilichokuwa kinatukia bali alimshutumu Mpemba kwamba huenda amechanganya hizo ‘sahani maalum’ walizokuwa wanazitumia kuwekea ‘ice-cream’ zao, Yaani akimaanisha kuwa zile anazodai Mpemba ni ‘ice cream’ zake (zile zilizoganda) sio za kwake, maana haiwezekani kikawaida zigande kabla ya zile za mwenzie aliyeziweka mapema zaidi na zikiwa zenye ubaridi. Mpemba naye hakuafiki hilo, kwa maana alikuwa na yakini na alichokiona, hakueleza waliumaliza vipi ubishani wao lakini kwa dhahiri ni tukio ambalo lilifungua ukurasa mpya katika maisha yake.
Siku kadhaa baada ya tukio hilo, Mpemba akiwa darasani aliamua kumuuliza mwalimu wake wa kidato cha 3 wa somo la Fizikia juu ya alichokishuhudia, lakini majibu ya mwalimu huyu yalimfanya abadili mawazo kwa muda. Kiufupi majibu ya mwalimu huyo yalikuwa sawa na ya yule rafiki yake Mpemba kuwa “Mpemba, Umechanganya sahani za kuhifadhia za ice-cream, hilo jambo haliwezi kutokea.”
Baada ya kumaliza kidato cha nne pale shuleni Magamba, Mpemba alijiunga na kidato cha tano katika shule ya sekondari Mkwawa, Iringa (sasa ni tawi la chuo kikuu cha Dar es salaam, MUCE), akichukua masomo ya sayansi. Siku moja wakiwa katika somo la Fizikia wanasomeshwa mada ya Joto (heat) wakati mwalimu anaielezea “Newton’s law of cooling” (kanuni ya upoaji ya bwana Newton), Mpemba alimuuliza mwalimu wake wa somo hilo wa kidato cha tano swali lile lile ambalo aliliuliza akiwa kidato cha tatu, “kwanini maziwa ya moto yanaganda haraka zaidi kuliko maziwa ya baridi?”
Mpemba alijikuta akiuliza swali hilo kwa sababu maalum, kwa kifupi kanuni hiyo ya bwana mkubwa Newton inaelekeza kwamba, kitu chenye joto-ridi linalokaribiana au kuwa na tofauti ndogo na joto-ridi la mazingira yake basi kitapoa haraka zaidi kuliko kile chenye joto-ridi kubwa sana zaidi ya joto-ridi la mazingira yake. Hii ndiyo kusema kwa mujibu wa kanuni hii ya Newton, Maziwa ya baridi yalitakiwa yagande haraka kwenye jokofu kuliko maziwa ya moto. Jambo ambalo Mpemba aliona ni tofauti na kilichotokea kwenye ‘ice cream’ zake.
Swali lake hili kwa mara nyengine likaibua sintofahamu na mabishano kati ya Mpemba kwa upande mmoja na Mwalimu na wanafunzi wenzie kwa upande wa pili. Mwalimu akisistiza kuwa jambo hilo haliwezekani kisayansi huku Mpemba naye akijenga hoja kuwa japo hakuna hayo maelezo ya Kisayansi lakini yeye amelishuhudia hilo likitokea kwa macho yake mwenyewe, wanafunzi wenzie hawakumuamini kabisa.
Pamoja na ushuhuda wake kukataliwa na wanafunzi pamoja na mwalimu wake lakini bado Mpemba alisimamia alichokiona, yeye aliamini si kila matokeo yalipaswa kwenda sabamba na hali iliyozoeleka na alitaka wenzie wajipe nafasi ya kukubali matokeo mapya tofauti na yale waliyoyazoea. Mwalimu wake baada ya kuchoshwa na Udadisi wake aliamua kuufunga mjadala huo wa kitaaluma kwa kebehi kuwa “hiyo (ya maziwa ya moto kuganda mapema zaidi ya maziwa ya baridi kwenye jokofu) itakuwa ni ‘Fizikia ya Mpemba’ na sio Fizikia ya Ulimwengu”.
Baada ya hapo ikawa ndio utani tena, kila alichokikosea shuleni pale kiliitwa ‘Cha Mpemba’, kwa mfano kwenye hesabu za“Alogarithims” alipokosea basi, mwalimu wa somo hilo na hata wanafunzi wenzie wangelisema hizo (alizokosea) ni ‘hesabu za Mpemba’ na sio hesabu za Algorithms! Lakini Mpemba, hakukatishwa tamaa na hali hiyo.
Siku moja akiwa katika Maabara ya Baiolojia shuleni hapo, aliamua kurudia jaribio lake, lakini badala ya kutumia maziwa mara hii alitumia maji, alijaza kiasi cha maji ujazo sawa kwenye “bikari” (Bilauri ndogo maalum zitumikazo maabara) mbili, moja akaweka maji ya baridi na nyengine akaweka maji ya moto, kisha akaziweka bikari mbili zile kwenye jokofu kwa muda wa saa moja.
Alipokuja kuziangalia baada ya hiyo saa moja alikuta bikari iliyokuwa na maji ya moto tayari imeshaanza kufanya barafu nyingi sana, wakati ile iliyokuwa na maji ya baridi ingali na maji na barafu kidogo! Hii ilizidi kumpa uhakika wa ugunduzi wake, ugunduzi uliokataliwa na waalimu wake wawili wa somo la Fizikia pamoja na wanafunzi wenzie.
Wakati mmoja wanafunzi wa kidato cha tano na sita shuleni Mkwawa walipata nafasi ya kutembelewa na Mhadhiri mwandamimizi kutoka Chuo Kikuu cha Dar es Salaam, Dk. Denis Osborne (wakati huo akiwa bado ni Daktari wa falsafa tu, sasa Profesa Osborne) ambaye alikuwa ni mtaalamu wa Fizikia. Osborne alialikwa shuleni pale na Mkuu wa shule hiyo ili aje kuwahamasisha wanafunzi wa shule hiyo kusoma kwa bidii ili wafaulu na wafanikiwe kujiunga na masomo ya Chuo kikuu.
Lakini akiwa ni mtaalamu wa Fizikia alizungumza kidogo kuhusu somo hilo, mwishoni Wanafunzi walipewa nafasi ya kumuuliza Dk. Osborne maswali mbalimbali mara baada kumaliza mazungumzo yake. Maswali yalikuwa mengi, yapo yaliyohusu namna ya kujiunga na chuo kikuu, idadi ya wanaotakiwa kuingia chuo kikuu, ugumu na wa somo la Fizikia chuo kikuu, unakuwa nani ukimaliza Sahahada ya Fizikia?, n.k. Lakini swali lilowavunja mbavu kwa kicheko wanafunzi wengi kama si wote, hata kupelekea wengine kuona aibu, ni swali alilouliza Erasto Mpemba.
Mpemba alimuuliza Dk. Osborne swali lile lile alilowahi kuwauliza mwanzoni walimu wake wawili wa Fizikia, tofauti ikiwa mara hii akiuliza kuhusu maji na siyo maziwa, na akiwa makini zaidi kujua joto-ridi la awali la maji yake, alimuuliza “Inakuaje ukijaza maji ya moto yenye nyuzi joto 100 za sentigredi na maji baridi yenye nyuzi joto 35 za sentigredi, kwa ujazo sawa kwenye ‘beaker’ mbili tofauti kisha ukaweka kwenye jokofu, maji yaliyokuwa na nyuzi joto 100 za sentigredi yanaganda kabla ya yale yaliyokuwa na nyuzi joto 35 za sentigredi?”
Dk. Osborne, kwanza alicheka kama walivyocheka wengine katika hadhara ile, kisha akamwambia Mpemba arudie swali lake. Mpemba akarudia kile kile alichokiuliza mara ya kwanza, Mara hii uzingatiaji wa Dk. Osborne ulikuwa mkubwa zaidi, mara baada ya Mpemba kurudia swali lake akamuuliza “una hakika umefanya hivyo?”
Mpemba akajibu ndio, nna hakika nimefanya, hapa Prof. Osborne alionesha utofauti wa hali ya juu katika kuiendea kesi hii! Kwanza alitaka kujiridhisha kama kweli alichosikia ndicho kilichoulizwa, pili alitaka kujua imani ya muuliza swali juu ya anachokiuliza (uhakika wake), na tatu na muhimu sana katika taaluma yoyote, alitaka kujua chanzo cha hoja, ndo maana akamuuliza (je ni kweli umefanya wewe mwenyewe?). Baada ya kujiridhisha na yote hayo alijibu swali la Mpemba kwa kumwambia kuwa “Sijui kwa kweli, lakini nakuahidi kuwa nitajaribu huo uchunguzi nikifika Dar es Salaam”.
Kinachofurahisha zaidi kutoka kwa Dk. Osborne sio namna alivyolisikiliza swali kwa umakini mkubwa, bali ni ile hali ya kuwa tayari kusikia na kupokea kitu kipya kutoka hata kwa mwanafunzi wa sekondari ya Kijijini Mkwawa. Jiulize ni maDokta, maProfesa au Walimu vyuoni, mashuleni na kwenye vituo vyetu vya utafiti walio tayari kupokea wazo jipya (ambalo halijatoka kwa wanasyansi wa nje) kutoka kwa wanafunzi wao au hata wafanyakazi wenzao waliochini yao kielimu? Ni wachache sana!
Wanafunzi wenzake, hasa wale wanaojiita vipanga, hawakufurahishwa na kitendo chake cha kuuliza swali ambalo wao waliliona ni la kipuuzi, walifikia hatua hata ya kumhoji “Hivi Mpemba umeelewa kweli ‘sura nzima’ ya kitabu inayoelezea Newtons law of cooling?” Lakini Mpemba siku zote alipenda kuwajibu kuwa “Nadharia wakati mwengine hutofautiana na majibu ya uchuguzi kwa vitendo”.
Dk. Osborne aliporudi Dar es salaam aliurudia ule uchunguzi, kwa kuweka maji ya moto na baridi kwenye ‘bikari’ mbili tofauti (ujazo sawa kama Mpemba), kisha akaziweka bilauri zile kwenye jokofu kwa muda wa saa moja. Majibu aliyopata ni kama yale aliyoyapata Mpemba kule Magamba na hatimaye pale Iringa. Kwa kutumia ufahamu wake kwenye sayansi (Fizikia), alijaribu kuelezea, sababu zinazoweza kupelekea hali hiyo, na hatimaye mwaka 1969, walichapisha chapisho lao (scientific paper) kwenye Jarida la ‘Journal of Physics Education’ lenye kichwa cha habari (Title), “Cool?” (Poa?).
Chapisho hilo ni moja ya Maandiko machache ya Kisayansi ambayo yameandikwa katika mtindo wa Masimulizi. Ni simulizi ya kweli katika ulimwengu wa sayansi na ugunduzi, Simulizi inayobeba mambo mengi na inayoonesha uhalisia wa mfumo mbovu wa elimu yetu. Maana hata baada ya kumaliza kidato sita, Mpemba alipotea kabisa katika ulimwengu wa sayansi na aliishia kusoma “Chuo cha uhifadhi Wanyamapori” badala ya kuwa Mwanasayansi.
Ni simulizi inayoonyesha kuwa pamoja na ukatishwaji tamaa mkubwa unaofanywa kwa wanafunzi mashuleni lakini pia hakuna juhudi zozote zinazofanywa kuviendeleza vipaji mbalimbali vinachomozwa na kuushinda mtihani huo wa kukatishwa tamaa. Kutokana na masimulizi haya tunaonyeshwa kuwa “Udhani” hata kama umeasisiwa na wanasayansi wakubwa wa kimagharibi na Amerika, bado unaweza kuwa na mapungufu katika kulielezea jambo husika, hivyo bado kuna nafasi ya kuzifanyia marekebisho na hata kuzipinga tafiti mbalimbali zilizowahi kufanywa.
Pia simulizi hii imetuonesha tofauti ya kuwa na wasomi ambao ni “wadadisi” na wale ambao ni wasomi “wahafidhina” wanaoendesha taaluma zao kiimla na kimazoea. Zaidi ya yote hii ni simulizi inayotufunza kuwa “Hakuna swali la kipuuzi”.
Chakusikitisha zaidi, ambacho ndicho kilichonisukuma kuandika makala hii, ni jinsi utafiti huu wa kujivunia, na wa kipekee, uliofanywa na wataaalam wetu ndani ya ardhi yetu, hautajwi wala kusimuliwa popote nchini, si katika shule wala vyuo vyetu. Baadhi ya vyanzo vya Kitafiti duniani vimeainisha kwamba “Mpemba effect” ni moja kati ya ‘Falsafa chache za Kifizikia’ (kama sio pekee tu) iliyopewa jina la mtafiti wa kiafrika.
Ajabu, hapa Tanzania tumeshindwa hata kumweka Mpemba kwenye vitabu vya hadithi vya shule za Msingi ili watoto wetu wajifunze, wahamasike na waamini kwamba inawezekana kuwa mwanasayansi mgunduzi hata bila kufika Chuo Kikuu. Hilo lingefanyika lingewapa fursa wanafunzi hawa ya kujifunza kujiamini na kutokata tamaa juu ya kile wanachokiamini au kukijua. Zaidi wangejifunza mbinu za kuhimili changamoto, wangetambua kwamba katika kila hatua ya maendeleo viko vizingiti vya kukatisha tamaa, na hivyo wangejifunza namna ya kuenenda katika nyakati hizo.
Kwa kuona umuhimu mkubwa wa “Mpemba effect” katika ulimwengu huu wa Sayansi na Teknolojia, Mwaka 2012 tu, Jarida ya ‘The Royal Society of Chemistry’ la Chuo Kikuu cha Cambridge cha Uingereza, ambalo ni moja ya Majarida Makongwe sana na yenye hadhi ya juu ya Kitaaluma duniani lilitangaza zawadi nono ya pesa kwa mtu au kikundi cha wanasayansi watakaoweza kutoa maelezo mazuri, bora na ya kujenga zaidi kuhusu “dhana” kwamba maji ya moto yanaganda mapema zaidi kabla ya maji ya baridi - “Mpemba effect”.
Watu zaidi ya ishirini na mbili elfu (22,000) walijitokeza, Kisha 11 wakaingia fainali, na hatimaye Nikola Bregovic kutoka Croatia ambaye ni mfanyakazi wa Maabara ya Kemia katika Chuo Kikuu cha Zagreb, akatangazwa kuwa mshindi. Januari 10, 2013 Mtanzania Erasto Bartholomeo Mpemba ndiye aliyepewa heshima kubwa ya kumtangaza mshindi na kumpa zawadi hiyo kwa niaba ya Jaribu la ‘The Royal Society of Chemistry’, tukio ambalo lilichochea hamasa juu ya Udadisi, Utafiti na Ugunduzi kwa vijana wengi wa Ulaya.
“Mpemba effect” iko bado na inaishi kwenye maabara mbalimbali duniani, kuanzia Ulaya, Amerika na Asia, lakini sio Tanzania. Tafiti mbali mbali zimeshafanywa (Katz, 2009, Esposito, 2008, na Auerbach, 1995), na bado zinaendelea kufanywa ili kutafuta sababu za msingi za “dhana” hii ili mwishowe iweze kuwekwa katika matumizi sahihi kama kanuni (law) kwa ajili ya maendeleo ya wanaadam.
Pichani ni Erasto B Mpemba akiwa pamoja na Profesa Denis Osborne katika moja ya Mikutano mbalimbali waliyohudhuria pamoja duniani. Picha na Maelezo haya ni kwa hisani kubwa ya Ndugu Ally Mahadhy, Mwanafunzi wa Kitanzania wa Shahada ya Uzamivu katika Chuo Kikuu cha Lund, Sweden.
Kwa Habari zaidi juu ya Nguli wa Kitanzania walio FAHARI YETU LIKE Ukurasa wetu wa WATANZANIA MASHUHURI ili upate kujifunza zaidi
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“MPEMBA EFFECT”: UDADISI, UTAFITI NA UGUNDUZI WA KITANZANIA
“MAJI ya moto yaliyochemka yanaganda (kuwa barafu) haraka zaidi kabla ya maji ya baridi”.
Ni ugunduzi wa kisayansi wa Mtanzania usiotajwa kwenye Vitabuni, Shuleni wala Vyuoni mwetu hapa nchini, lakini ni gumzo la kitaaluma katika Vyuo na taasisi mbalimbali za elimu za Mataifa mbalimbali. Ni “Udhani” (Hypothesis) unaoumiza vichwa vya wanasayansi wa Dunia yote, kuanzia Ulaya Magharibi, Amerika mpaka Asia.
Ugunduzi huu wa kisayansi unaeoelezea “sifa ya kipekee ya maji” ulifanywa na mwanafunzi wa kidato cha tatu wa Kitanzania katika shule ya sekondari Magamba, Lushoto, Mkoani Tanga, mwaka 1963. Jina la Mwanafunzi huyo ni Erasto Bartholomeo Mpemba, jina ambalo sifa hiyo ya maji (physical phenomenon) imepewa, yaani “Mpemba effect”.
Erasto Batholomeo Mpemba, kama ilivyokuwa kwa wanasayansi wengine maarufu duniani, alifanikiwa kugundua sifa hii muhimu ya maji kama ajali tu (accidental discovery), kama ilivyokuwa kwa Wagunduzi wengine wa Kisayansi wa Kaliba yake, Mfano Friedrich August Kekule (Mgunduzi wa Udhani wa Umbo la Kekule katika Sayansi ya Kemia), Isaack Newton, Archemedes na wengineo, Mpemba naye amefanya ugunduzi wake baada ya tukio la kawaida tu katika maisha yake ambalo lilileta majibu yasiyo ya kawaida na yanayofikirisha.
Katika andiko mashuhuri juu ya “Mpemba Effect” lililochapishwa katika Jarida la Kitaaluma la ‘Journal of Physics Education’ la mwaka 1969, Mpemba anaanza kujieleza ifuatavyo, “Jina langu ni Erasto B. Mpemba, nitawaambia ugunduzi wangu ambao umetokana na matumizi mabaya ya jokofu”.
Masimulizi hayo ya Mpemba katika andiko hilo yanaainisha kwa undani mazingira ya elimu ya Tanzania tokea miaka ile ya mwanzo mwa Taifa letu mpaka sasa. Kikawaida wanafunzi wengi wa kitanzania wanaosema kwenye shule za umma, ama hufanya biashara za walimu wakiwa madarasani wakati wa vipindi au baada ya vipindi, au hufanya biashara za Wazazi wao. Erasto Mpemba na wenzake kadhaa pale shuleni Magamba (Hivi sasa ni Sebastian Kolowa Memorial University, SEKOMU), walikuwa wanauza ‘ice-cream’ baada ya kumaliza vipindi vya masomo.
Ingawa haijawekwa wazi kwenye masimulizi hayo kwamba, mradi huu ulikuwa wa shule ama wa mwalimu tu, lakini wanafunzi waliohusika na biashara hii walikuwa wengi, hivyo iliwabidi wagombee nafasi kwenye jokofu wakati wa kutengeneza ‘ice cream’ hizo. Kwa kawaida ilikuwa wananunua maziwa asubuhi na mapema kutoka vijiji vya jirani kama vile Maina, Mazinde Juu, Mabughai, Kost na kwengineo; wanayachemsha, wanaacha yapoe kisha wanayaweka kwenye jokofu kabla ya kwenda darasani.
Wakimaliza vipindi vyao madarasani, huchukuwa ‘ice-cream’ zao zilizoganda na kupeleka Lushoto-mjini kwa mauzo. Yule atakayekuwa kakosa nafasi ya kuweka ‘ice cream’ zake kwenye jokofu itampasa asubiri mpaka wenzake watoe ice-cream zao nyakati za mchana kwenda kwenye mauzo ndipo na yeye apate nafasi ya kuweka za kwake. Lakini pia kwa yule aliyeweka mwanzo kabla ya mwenzake, alikuwa na uhakika wa kuanza kupeleka ‘ice-cream’ zake sokoni kabla ya mwezake, maana anayeweka mwanzo ice cream zake zitaganda mapema zaidi kabla ya wengine. Hivyo kulikuwa na changamoto mbili muhimu kwa Mpemba na wenzake, kupata nafasi ya kuweka ‘ice cream’ kwenye jokofu, na kuweka mapema zaidi.
Siku moja wakati Mpemba anachemsha maziwa ya ice-cream, mwenzake (mshindani wake kwenye biashara ya ice-cream) aliamua asichemshe maziwa yake ya kutengenezea ice-cream ili awahi nafasi anayoipenda kwenye jokofu kabla Mpemba hajaweka kwenye nafasi yake hiyo. Kwa akili zake za kitoto hakujali afya za walaji, bali cha muhimu kwake ilikuwa awahi nafasi ndani ya jokofu. Mpemba aliendelea kuchemsha maziwa yake, lakini kwa bahati nzuri au mbaya ikawa imebaki nafasi moja tu kwenye jokofu, hivyo naye kwa hofu ya kupoteza hiyo nafasi moja iliyobaki kwenye jokofu akaamua asisubiri mpaka maziwa yapoe ndipo ayaweke jokofuni bali akayewaka hivyo hivyo yakiwa ya moto bado. Japo alijua ni matumizi mabaya ya jokofu, lakini aliamua kufanya hivyo. Anasimuliwa mwenyewe kwenye “andiko” hilo.
Baada ya saa moja na nusu hivi, wakiwa kwenye mapumziko ya vipindi vya darasani, Mpemba na mwenzake waliamua kwenda kwenye jokofu kuangalia hali ya bidhaa zao na pia usalama wa jokofu. Zaidi Mpemba alikuwa na wasiwasi kwa vile aliweka maziwa ya moto kwenye jokofu, hivyo alitaka kwenda kuhakiki usalama wa jokofu. Walichokiona ndicho ambacho leo hii kinajulikana kama “Mpemba effect”, Maziwa ya Mpemba ambayo aliyaweka kwenye jokofu yakiwa ya moto yalishaganda na kuwa ‘ice-cream’, haliyakuwa maziwa ya yule mwenzake aliyeweka mwanzoni zaidi ‘Maziwa ya baridi bila ya kuyachemsha’, yakiwa bado yangali tepe tepe (hayajaganda kuwa ice-cream).
Hali hii ilipekea sintofahamu kubwa kati yao, kwani yule mwanafunzi mwenzake hakuamini kilichokuwa kinatukia bali alimshutumu Mpemba kwamba huenda amechanganya hizo ‘sahani maalum’ walizokuwa wanazitumia kuwekea ‘ice-cream’ zao, Yaani akimaanisha kuwa zile anazodai Mpemba ni ‘ice cream’ zake (zile zilizoganda) sio za kwake, maana haiwezekani kikawaida zigande kabla ya zile za mwenzie aliyeziweka mapema zaidi na zikiwa zenye ubaridi. Mpemba naye hakuafiki hilo, kwa maana alikuwa na yakini na alichokiona, hakueleza waliumaliza vipi ubishani wao lakini kwa dhahiri ni tukio ambalo lilifungua ukurasa mpya katika maisha yake.
Siku kadhaa baada ya tukio hilo, Mpemba akiwa darasani aliamua kumuuliza mwalimu wake wa kidato cha 3 wa somo la Fizikia juu ya alichokishuhudia, lakini majibu ya mwalimu huyu yalimfanya abadili mawazo kwa muda. Kiufupi majibu ya mwalimu huyo yalikuwa sawa na ya yule rafiki yake Mpemba kuwa “Mpemba, Umechanganya sahani za kuhifadhia za ice-cream, hilo jambo haliwezi kutokea.”
Baada ya kumaliza kidato cha nne pale shuleni Magamba, Mpemba alijiunga na kidato cha tano katika shule ya sekondari Mkwawa, Iringa (sasa ni tawi la chuo kikuu cha Dar es salaam, MUCE), akichukua masomo ya sayansi. Siku moja wakiwa katika somo la Fizikia wanasomeshwa mada ya Joto (heat) wakati mwalimu anaielezea “Newton’s law of cooling” (kanuni ya upoaji ya bwana Newton), Mpemba alimuuliza mwalimu wake wa somo hilo wa kidato cha tano swali lile lile ambalo aliliuliza akiwa kidato cha tatu, “kwanini maziwa ya moto yanaganda haraka zaidi kuliko maziwa ya baridi?”
Mpemba alijikuta akiuliza swali hilo kwa sababu maalum, kwa kifupi kanuni hiyo ya bwana mkubwa Newton inaelekeza kwamba, kitu chenye joto-ridi linalokaribiana au kuwa na tofauti ndogo na joto-ridi la mazingira yake basi kitapoa haraka zaidi kuliko kile chenye joto-ridi kubwa sana zaidi ya joto-ridi la mazingira yake. Hii ndiyo kusema kwa mujibu wa kanuni hii ya Newton, Maziwa ya baridi yalitakiwa yagande haraka kwenye jokofu kuliko maziwa ya moto. Jambo ambalo Mpemba aliona ni tofauti na kilichotokea kwenye ‘ice cream’ zake.
Swali lake hili kwa mara nyengine likaibua sintofahamu na mabishano kati ya Mpemba kwa upande mmoja na Mwalimu na wanafunzi wenzie kwa upande wa pili. Mwalimu akisistiza kuwa jambo hilo haliwezekani kisayansi huku Mpemba naye akijenga hoja kuwa japo hakuna hayo maelezo ya Kisayansi lakini yeye amelishuhudia hilo likitokea kwa macho yake mwenyewe, wanafunzi wenzie hawakumuamini kabisa.
Pamoja na ushuhuda wake kukataliwa na wanafunzi pamoja na mwalimu wake lakini bado Mpemba alisimamia alichokiona, yeye aliamini si kila matokeo yalipaswa kwenda sabamba na hali iliyozoeleka na alitaka wenzie wajipe nafasi ya kukubali matokeo mapya tofauti na yale waliyoyazoea. Mwalimu wake baada ya kuchoshwa na Udadisi wake aliamua kuufunga mjadala huo wa kitaaluma kwa kebehi kuwa “hiyo (ya maziwa ya moto kuganda mapema zaidi ya maziwa ya baridi kwenye jokofu) itakuwa ni ‘Fizikia ya Mpemba’ na sio Fizikia ya Ulimwengu”.
Baada ya hapo ikawa ndio utani tena, kila alichokikosea shuleni pale kiliitwa ‘Cha Mpemba’, kwa mfano kwenye hesabu za“Alogarithims” alipokosea basi, mwalimu wa somo hilo na hata wanafunzi wenzie wangelisema hizo (alizokosea) ni ‘hesabu za Mpemba’ na sio hesabu za Algorithms! Lakini Mpemba, hakukatishwa tamaa na hali hiyo.
Siku moja akiwa katika Maabara ya Baiolojia shuleni hapo, aliamua kurudia jaribio lake, lakini badala ya kutumia maziwa mara hii alitumia maji, alijaza kiasi cha maji ujazo sawa kwenye “bikari” (Bilauri ndogo maalum zitumikazo maabara) mbili, moja akaweka maji ya baridi na nyengine akaweka maji ya moto, kisha akaziweka bikari mbili zile kwenye jokofu kwa muda wa saa moja.
Alipokuja kuziangalia baada ya hiyo saa moja alikuta bikari iliyokuwa na maji ya moto tayari imeshaanza kufanya barafu nyingi sana, wakati ile iliyokuwa na maji ya baridi ingali na maji na barafu kidogo! Hii ilizidi kumpa uhakika wa ugunduzi wake, ugunduzi uliokataliwa na waalimu wake wawili wa somo la Fizikia pamoja na wanafunzi wenzie.
Wakati mmoja wanafunzi wa kidato cha tano na sita shuleni Mkwawa walipata nafasi ya kutembelewa na Mhadhiri mwandamimizi kutoka Chuo Kikuu cha Dar es Salaam, Dk. Denis Osborne (wakati huo akiwa bado ni Daktari wa falsafa tu, sasa Profesa Osborne) ambaye alikuwa ni mtaalamu wa Fizikia. Osborne alialikwa shuleni pale na Mkuu wa shule hiyo ili aje kuwahamasisha wanafunzi wa shule hiyo kusoma kwa bidii ili wafaulu na wafanikiwe kujiunga na masomo ya Chuo kikuu.
Lakini akiwa ni mtaalamu wa Fizikia alizungumza kidogo kuhusu somo hilo, mwishoni Wanafunzi walipewa nafasi ya kumuuliza Dk. Osborne maswali mbalimbali mara baada kumaliza mazungumzo yake. Maswali yalikuwa mengi, yapo yaliyohusu namna ya kujiunga na chuo kikuu, idadi ya wanaotakiwa kuingia chuo kikuu, ugumu na wa somo la Fizikia chuo kikuu, unakuwa nani ukimaliza Sahahada ya Fizikia?, n.k. Lakini swali lilowavunja mbavu kwa kicheko wanafunzi wengi kama si wote, hata kupelekea wengine kuona aibu, ni swali alilouliza Erasto Mpemba.
Mpemba alimuuliza Dk. Osborne swali lile lile alilowahi kuwauliza mwanzoni walimu wake wawili wa Fizikia, tofauti ikiwa mara hii akiuliza kuhusu maji na siyo maziwa, na akiwa makini zaidi kujua joto-ridi la awali la maji yake, alimuuliza “Inakuaje ukijaza maji ya moto yenye nyuzi joto 100 za sentigredi na maji baridi yenye nyuzi joto 35 za sentigredi, kwa ujazo sawa kwenye ‘beaker’ mbili tofauti kisha ukaweka kwenye jokofu, maji yaliyokuwa na nyuzi joto 100 za sentigredi yanaganda kabla ya yale yaliyokuwa na nyuzi joto 35 za sentigredi?”
Dk. Osborne, kwanza alicheka kama walivyocheka wengine katika hadhara ile, kisha akamwambia Mpemba arudie swali lake. Mpemba akarudia kile kile alichokiuliza mara ya kwanza, Mara hii uzingatiaji wa Dk. Osborne ulikuwa mkubwa zaidi, mara baada ya Mpemba kurudia swali lake akamuuliza “una hakika umefanya hivyo?”
Mpemba akajibu ndio, nna hakika nimefanya, hapa Prof. Osborne alionesha utofauti wa hali ya juu katika kuiendea kesi hii! Kwanza alitaka kujiridhisha kama kweli alichosikia ndicho kilichoulizwa, pili alitaka kujua imani ya muuliza swali juu ya anachokiuliza (uhakika wake), na tatu na muhimu sana katika taaluma yoyote, alitaka kujua chanzo cha hoja, ndo maana akamuuliza (je ni kweli umefanya wewe mwenyewe?). Baada ya kujiridhisha na yote hayo alijibu swali la Mpemba kwa kumwambia kuwa “Sijui kwa kweli, lakini nakuahidi kuwa nitajaribu huo uchunguzi nikifika Dar es Salaam”.
Kinachofurahisha zaidi kutoka kwa Dk. Osborne sio namna alivyolisikiliza swali kwa umakini mkubwa, bali ni ile hali ya kuwa tayari kusikia na kupokea kitu kipya kutoka hata kwa mwanafunzi wa sekondari ya Kijijini Mkwawa. Jiulize ni maDokta, maProfesa au Walimu vyuoni, mashuleni na kwenye vituo vyetu vya utafiti walio tayari kupokea wazo jipya (ambalo halijatoka kwa wanasyansi wa nje) kutoka kwa wanafunzi wao au hata wafanyakazi wenzao waliochini yao kielimu? Ni wachache sana!
Wanafunzi wenzake, hasa wale wanaojiita vipanga, hawakufurahishwa na kitendo chake cha kuuliza swali ambalo wao waliliona ni la kipuuzi, walifikia hatua hata ya kumhoji “Hivi Mpemba umeelewa kweli ‘sura nzima’ ya kitabu inayoelezea Newtons law of cooling?” Lakini Mpemba siku zote alipenda kuwajibu kuwa “Nadharia wakati mwengine hutofautiana na majibu ya uchuguzi kwa vitendo”.
Dk. Osborne aliporudi Dar es salaam aliurudia ule uchunguzi, kwa kuweka maji ya moto na baridi kwenye ‘bikari’ mbili tofauti (ujazo sawa kama Mpemba), kisha akaziweka bilauri zile kwenye jokofu kwa muda wa saa moja. Majibu aliyopata ni kama yale aliyoyapata Mpemba kule Magamba na hatimaye pale Iringa. Kwa kutumia ufahamu wake kwenye sayansi (Fizikia), alijaribu kuelezea, sababu zinazoweza kupelekea hali hiyo, na hatimaye mwaka 1969, walichapisha chapisho lao (scientific paper) kwenye Jarida la ‘Journal of Physics Education’ lenye kichwa cha habari (Title), “Cool?” (Poa?).
Chapisho hilo ni moja ya Maandiko machache ya Kisayansi ambayo yameandikwa katika mtindo wa Masimulizi. Ni simulizi ya kweli katika ulimwengu wa sayansi na ugunduzi, Simulizi inayobeba mambo mengi na inayoonesha uhalisia wa mfumo mbovu wa elimu yetu. Maana hata baada ya kumaliza kidato sita, Mpemba alipotea kabisa katika ulimwengu wa sayansi na aliishia kusoma “Chuo cha uhifadhi Wanyamapori” badala ya kuwa Mwanasayansi.
Ni simulizi inayoonyesha kuwa pamoja na ukatishwaji tamaa mkubwa unaofanywa kwa wanafunzi mashuleni lakini pia hakuna juhudi zozote zinazofanywa kuviendeleza vipaji mbalimbali vinachomozwa na kuushinda mtihani huo wa kukatishwa tamaa. Kutokana na masimulizi haya tunaonyeshwa kuwa “Udhani” hata kama umeasisiwa na wanasayansi wakubwa wa kimagharibi na Amerika, bado unaweza kuwa na mapungufu katika kulielezea jambo husika, hivyo bado kuna nafasi ya kuzifanyia marekebisho na hata kuzipinga tafiti mbalimbali zilizowahi kufanywa.
Pia simulizi hii imetuonesha tofauti ya kuwa na wasomi ambao ni “wadadisi” na wale ambao ni wasomi “wahafidhina” wanaoendesha taaluma zao kiimla na kimazoea. Zaidi ya yote hii ni simulizi inayotufunza kuwa “Hakuna swali la kipuuzi”.
Chakusikitisha zaidi, ambacho ndicho kilichonisukuma kuandika makala hii, ni jinsi utafiti huu wa kujivunia, na wa kipekee, uliofanywa na wataaalam wetu ndani ya ardhi yetu, hautajwi wala kusimuliwa popote nchini, si katika shule wala vyuo vyetu. Baadhi ya vyanzo vya Kitafiti duniani vimeainisha kwamba “Mpemba effect” ni moja kati ya ‘Falsafa chache za Kifizikia’ (kama sio pekee tu) iliyopewa jina la mtafiti wa kiafrika.
Ajabu, hapa Tanzania tumeshindwa hata kumweka Mpemba kwenye vitabu vya hadithi vya shule za Msingi ili watoto wetu wajifunze, wahamasike na waamini kwamba inawezekana kuwa mwanasayansi mgunduzi hata bila kufika Chuo Kikuu. Hilo lingefanyika lingewapa fursa wanafunzi hawa ya kujifunza kujiamini na kutokata tamaa juu ya kile wanachokiamini au kukijua. Zaidi wangejifunza mbinu za kuhimili changamoto, wangetambua kwamba katika kila hatua ya maendeleo viko vizingiti vya kukatisha tamaa, na hivyo wangejifunza namna ya kuenenda katika nyakati hizo.
Kwa kuona umuhimu mkubwa wa “Mpemba effect” katika ulimwengu huu wa Sayansi na Teknolojia, Mwaka 2012 tu, Jarida ya ‘The Royal Society of Chemistry’ la Chuo Kikuu cha Cambridge cha Uingereza, ambalo ni moja ya Majarida Makongwe sana na yenye hadhi ya juu ya Kitaaluma duniani lilitangaza zawadi nono ya pesa kwa mtu au kikundi cha wanasayansi watakaoweza kutoa maelezo mazuri, bora na ya kujenga zaidi kuhusu “dhana” kwamba maji ya moto yanaganda mapema zaidi kabla ya maji ya baridi - “Mpemba effect”.
Watu zaidi ya ishirini na mbili elfu (22,000) walijitokeza, Kisha 11 wakaingia fainali, na hatimaye Nikola Bregovic kutoka Croatia ambaye ni mfanyakazi wa Maabara ya Kemia katika Chuo Kikuu cha Zagreb, akatangazwa kuwa mshindi. Januari 10, 2013 Mtanzania Erasto Bartholomeo Mpemba ndiye aliyepewa heshima kubwa ya kumtangaza mshindi na kumpa zawadi hiyo kwa niaba ya Jaribu la ‘The Royal Society of Chemistry’, tukio ambalo lilichochea hamasa juu ya Udadisi, Utafiti na Ugunduzi kwa vijana wengi wa Ulaya.
“Mpemba effect” iko bado na inaishi kwenye maabara mbalimbali duniani, kuanzia Ulaya, Amerika na Asia, lakini sio Tanzania. Tafiti mbali mbali zimeshafanywa (Katz, 2009, Esposito, 2008, na Auerbach, 1995), na bado zinaendelea kufanywa ili kutafuta sababu za msingi za “dhana” hii ili mwishowe iweze kuwekwa katika matumizi sahihi kama kanuni (law) kwa ajili ya maendeleo ya wanaadam.
Pichani ni Erasto B Mpemba akiwa pamoja na Profesa Denis Osborne katika moja ya Mikutano mbalimbali waliyohudhuria pamoja duniani. Picha na Maelezo haya ni kwa hisani kubwa ya Ndugu Ally Mahadhy, Mwanafunzi wa Kitanzania wa Shahada ya Uzamivu katika Chuo Kikuu cha Lund, Sweden.
Kwa Habari zaidi juu ya Nguli wa Kitanzania walio FAHARI YETU LIKE Ukurasa wetu wa WATANZANIA MASHUHURI ili upate kujifunza zaidi
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FRANCIS DA DON
JF-Expert Member
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Lakini shangaa toka chekechea hadi chuo sijawahi kumsikia tukifundishwa darasani, hivi kwanini tunadharau wetu na kutukuza wao?
Mwanamageuko
JF-Expert Member
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Taifa letu halijawahi kuwahitaji watu wa aina hiyo wala kutambua umuhimu wao. Wako wanaohitaji kutambulika na kutambuliwa zaidi kuliko watu wenye taaluma zao na gunduzi zenye manufaa kwa nchi na dunia. Siku tukitambua michango ya wataalamu wetu tutaona taifa litakavyosonga mbele... Tuendelee na siasa na ubwabwajaji kwa sasa maana ndio vyenye manufaa zaidi kuliko...
lembu
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Japokuwa kuna mabishano makali sana kati ya wanasayansi wanaoikubali hii effect na wale wanaopinga, wale wanaopinga wakisema haina evidence ya kutosha na kwamba experiment za hii effect zinaleta results tofauti tofauti hata kama ukiifanyia kwenye the same platform
Kwa maoni yangu hii phenomena ya "Mpemba Effect" ina faida kubwa sana kwenye ulimwengu wa sayansi na masiaha ya kila siku kwa sababu zifuatazo
Kwa maoni yangu hii phenomena ya "Mpemba Effect" ina faida kubwa sana kwenye ulimwengu wa sayansi na masiaha ya kila siku kwa sababu zifuatazo
- Kwanza imezua majadiliano na tafiti mbalimbali za wanaopinga na wanaokubali ili kup[ata matokeo bora Zaidi
- Pili kama ilivyo kawaida ya ugunduzi, haukamiliki kwa mgunduzi mmoja bali inakamilishwa na wanaofuata kwa kujenga juu yake kama ilivyo kwenye ugunduzi wa kompyuta nk
- Tatu huu ugunduzi sio tu utaleta faida ya kuokoa matumizi ya nishati kama alivyosema mwenyewe kuwa kulikuwa na matumzi mabovu ya jokovu, hivyo hivyo kuna matumiziz mabovu ya nishati ambamo huu ugunduzi ukikamilika utasaidia kuwa na matumizi sahihi ya nishati
Wanaotengeneza barafu wanajua significance yake. Kilangila.
carcinoma
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Kwa mara ya kwanza nilimsikia mpemba nikiwa form 5..
Kumbe hata google yupo sana tu lkn sijui kwa nini watanzania hatumjui?
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Kumbe hata google yupo sana tu lkn sijui kwa nini watanzania hatumjui?
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KWEZISHO
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Utashangaa Wema Sepenga ni maarufu kuliko hii falsafa
carcinoma
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Inashangaza mkuu.
Eti pierre wa liquid ni maarufu zaidi ya mpemba
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KWEZISHO
JF-Expert Member
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Duhh! Ama kweli ukistaajabu ya Mussa utaona ya Firrauni
Mangungo II
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2007 ulikuwepo humu ndani we jamaa lazima utakuwa babu halafu eti umezaliwq 1990 hahahah
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