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Kudos Project:现在是时候了:重新审视“姆潘巴效应“

已有 2995 次阅读 2021-8-26 11:19 |系统分类:论文交流

It’s about time: Revisiting the Mpemba effect



Project DOI: 10.26303/30fe-t430


Kudos project 的链接:



What is it about?



The “Mpemba effect” describes the phenomenon in which hot water appears to freeze faster than cold water. Descriptions of the effect date back to the writings of Aristotle. While modern scientists have ventured explanations for the Mpemba effect and variations thereof, the legitimacy of the effect has often been called into question. Reasons for this include the inability to reproduce the effect consistently across experiments and variations in how the primary outcome is defined (e.g., freezing vs. cooling to a certain temperature).

Jian’an Wang, former professor of physics at Shenzhen University, offers a new explanation based on analyzing the relationship between time and velocity in his modified special relativity, the relationship between time and gravitational field in general relativity, the gravitational redshift and the blackbody radiation theorem.



According to Wang, increasing the temperature of an object has the same effect as reducing the intensity of the gravitational field,both can increase the frequency of radiation photons and speed up the time on the object.



Using the above conclusion on the nature of time, Wang analyzed the Mpamba effect and gave an explanation: the reason why hot water froze first than cold water is that the time on hot water is faster than on cold water.



Jian’an Wang received his bachelor’s degree in experimental nuclear physics in 1982 from the Department of Modern Physics at the University of Science and Technology of China. Upon graduating, he was assigned to the China Institute of Atomic Energy, where he studied nuclear reactions of charged particles. In 1985, he was admitted to the Department of Physics at Huazhong University of Science and Technology, from which he received a master’s degree. He obtained a Ph.D. in 1996 from McGill University in Montreal, Quebec, Canada, for his research on laser luminescent materials. Wang entered the Department of Physics at Shenzhen University as an assistant professor in 1999 and retired in 2012. 


Why is it important?



Definitive and reproducible demonstrations of the Mpemba effect are still lacking. And it’s unclear whether a valid explanation of the phenomenon would be trivial or groundbreaking.



Regardless, the reported effect has inspired creative thinking on the part of numerous scientists and will likely to continue to capture the imagination of scientists and science enthusiasts alike.



Audience Briefings



Press 新闻


Hot clocks run fast


July 30, 2021 – China – Clocks help keep our busy lives in synch and on schedule. But throughout our day, we can’t help but feel that time is often subjective.



Sometimes it seems to fly. Sometimes it undoubtedly drags.


Thanks to Einstein's theory of special relativity and general relativity. We now know that time is not subjective, but is related to the velocity of the object and the strength of the gravitational field in the space in which it is located.

多亏了爱因斯坦的狭义相对论和广义相对论, 我们现在知道时间不是主观的,是与物体的运动速度和所处空间的引力场强度有关的。


The faster the object is moving the slower time on the object, the stronger the gravitational field in the space in which the object is located the slower time on the object.



It follows that space and time are inextricably linked. Massive or fast-moving objects experience time differently than do low-mass or slow-moving objects.



Massive or faster things run on a slower clock. While these differences in time perception have been registered on earth, it's usually been with the aid of advanced instruments like atomic clocks.



Now, a recent preprint suggests that you might also find the same bizarre physics at work in your freezer.



Jian'an Wang, former professor at Shenzhen University, suggests that the fickleness of time could help explain the well-known “Mpemba effect,” the observation that in certain cases hot water freezes faster than cold water.



The effect is named after Erasto Bartholomeo Mpemba. When he was a student in Tanzania in the 1960s, with the help of a physics professor, he verified the bizarre phenomenon that his hot ice cream mixture froze faster than a cold one. But descriptions of the phenomenon date as far back as the writings of Aristotle.

这一效应以Erasto Bartholomeo Mpemba的名字命名。20世纪60年代,当他还是坦桑尼亚的一名学生时,他在一位物理学教授的帮助下,验证了他的热冰淇淋混合物比冷冰淇淋混合物结冰得更快这一奇异现象。但是对这一现象的描述可以追溯到亚里士多德的著作。


Since then, numerous scientists have ventured an explanation, including big names such as Francis Bacon, René Descartes, and Joseph Black. While the very existence of the effect has been called into question throughout the years, a recent experiment by Avinash Kumar and John Bechhoefer from Simon Fraser University involving glass beads as stand-ins for water molecules offers up the most definitive evidence for the legitimacy of the Mpemba effect.

从那时起,包括弗朗西斯·培根、René笛卡儿和约瑟夫·布莱克等大科学家在内的众多科学家都提出了一种解释。尽管多年来这种效应的存在一直受到质疑,但西蒙弗雷泽大学(Simon Fraser University)的阿维纳什·库马尔(Avinash Kumar)和约翰·贝赫霍费尔(John Bechhoefer)最近进行的一项实验,为潘巴效应的存在提供了最明确的证据,实验中他们用玻璃珠代替了水分子。


That comes as no surprise to Wang, whose re-couching of Einstein’s mathematics in terms of an energy background he calls “ether” chimes well with observations of the Mpemba effect.



This ether, according to Wang, accounts for all the classically odd features produced by special relativity: the increase in mass of moving objects, the apparent invariance of the speed of light, size contraction, and most relevantly, time dilation.

王博士认为,这种以太解释了狭义相对论产生的所有经典的奇异特征: 运动物体质量的增加、光速的表观不变性、尺寸的收缩,以及(与姆潘巴效应)最相关的时间膨胀。


Wang suggested that time on a moving object slows down because an increase in the speed of the moving object relative to the ether (energy) leads to an increase in the kinetic energy of the moving object, the energy density of the space around the object, which slows down time on the object.



Time slows down on a moving object in the same way that time slows down on an object in a gravitational field. That is, the higher the energy density in space, the slower the time on an object in space.



By analyzing the law of blackbody radiation, Wang further believes that increasing the temperature of an object and reducing the energy density of the space in which the object is located have the same effect, that is, both can accelerate the time on the object.



From this, Wang obtained a relation between time and absolute temperature, that is, when an object radiates energy outward, the time on the object is proportional to the fourth power of the absolute temperature of the object:



where t’ is the time on the object, μ is a constant, σ is the Stefan-Boltzmann constant, T is the absolute temperature.


上式中 t'是物体上的时间,μ 是常数,σ 是Stefan-Boltzmann常数,T 是绝对温度。


So, hotter objects would seem to experience a faster time flow than cooler objects and therefore reach equilibrium with its surroundings (i.e., freeze inside a freezer) faster.



While experiments are needed to test this theory, it could apply to much less mundane phenomena than those found in the kitchen.



Wang notes a link between his theory and the physics of our expanding universe—specifically, the luminescence of celestial bodies such as quasars and stars and planetary cooling.



Who is involved?



Vivien Pinner and Dr. Jian’an wang

Vivien Pinner 和王建安博士


Kudos project 的链接:



上一篇:Kudos Project:没有什么是理所当然的: 重温现代物理学原理
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