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Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Scientists watch how heat travels through the "pencil leader" at the speed of sound

Scientists watch how heat travels through the "pencil leader" at the speed of sound



Scientists have seen something magical that happens inside the graphite. What the pencil is made of: The heat moves in waves at the speed of sound.

This is a good reason for several reasons: Heat should not move like a wave – it usually diffuses and bounces off rocking molecules in all directions; If the heat can move in the form of a wave, it can move in one direction in mass direction from its source, which resembles energy immediately from the object. One day, the behavior of transferring heat in graffiti can be used to cool microelectronics. That is, if they can make it work at a reasonable temperature (they worked at temperatures that lower bone temperature minus 240 degrees Fahrenheit, or minus 1

51 degrees Celsius).

"If it reaches room temperature in some materials, then there are prospects for some applications," said researcher Kate Nelson, a chemist at the Massachusetts Institute of Technology, who said it was the highest temperature that everyone saw in this behavior. [The 18 Biggest Unsolved Mysteries in Physics]

The researchers described the "normal" motion of heat with the help of a heated kettle – After turning off the burner, the thermal energy closes on the air molecules that collide with each other and transfer heat into the process. These molecules rebound in These are some of these molecules that are scattered back to the kettle, and then the water with the kettle and the environment reach the equilibrium at the same temperature

In solids, the molecules do not move because the atoms are fixed in position. "What can move is sound waves, "said Nelson, who spoke with Live Science, along with co-author Gan Chen, mechanical engineer MIT.

Faster, heat the hop to phonons or small packages of sound vibration; phonons can bounce and scatter, transferring heat, just as the molecules of air make from the kettle. [What’s That Noise? 11 Strange and Mysterious Sounds on Earth]

This is not what happened in this new experiment.

Chen's preliminary theoretical work assumed that heat could move like a wave when moving through graphite or graphene. To test this, MIT researchers crossed two laser rays on the surface of their graphite, creating a so-called interference pattern, in which there were parallel lines of light and no light. This created the same picture of hot and unheated areas on the surface of graphite. Then they aimed at the laser another laser beam to see what happened after it got into graphite. "As a rule, heat is gradually diffused from the heated areas to unheated areas, until the temperature is wasted," said Nelson. "Instead, the heat is from warm to unheated areas, and flows even after the temperature has been leveled everywhere, so unheated regions were actually warmer than the first heated regions." The warmed regions, meanwhile, have become even cooler than unheated regions. And all this happened by breathing quickly – at about the same speed that the sound usually travels in graffiti. [8 Ways You Can See Einstein’s Theory of Relativity in Real Life]

"Heat flooded much faster because it was moving in the form of a wave without dispersion," said Nelson Live Science.

How they got such a strange behavior, which scientists call the "second sound"

"From a fundamental point of view, this is simply not ordinary behavior. The second sound was measured only in several materials ever, at any temperature Anything we observe is far from the usual challenges to us

Here's what they think is happening: graphite, or 3D material, has a layered structure in which thin carbon layers are unlikely to know what else is there and so they behave like graphene, which is a 2D material. Because Nelson calls it "low the phonons that carry heat in one layer of graphite, rarely bounce back and dissipate other layers much more rarely. In addition, phonons that can be formed in graffiti have wavelengths which are basically too large to be reflected back after being partitioned into atoms in These small sound packets are slightly scattered, but travel mostly in one direction, that is, on average, they can travel a long distance much faster.

Their research was published today (March 14th) in the journal Science. Editor's Note: This article has been updated to clarify some of the experimental methods and the fact that the heat passed at about the same speed as the sound moving through graphite, not air, as noted earlier.

Originally published on Live Science .


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