قالب وردپرس درنا توس
Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Scientists watch the heat move through the pencil lead sound

Scientists watch the heat move through the pencil lead sound



Scientists have seen something inside the magic graphite, what your pencil is made of: Heat has moved in waves by speed of sound

This is quite a lot for several reasons: heat does not move like a wave – it usually scatters and unfolds from jiggly molecules in all directions ; If the heat can go like a wave, it can move in one direction to the mass from its source, some zapping energy at one time from the object. One day, this heat transfer action on graphite can be used to open up microelectronics. This means that if they can get the right temperature (they worked at a cooling temperature of minus 240 degrees Celsius or minus 151 degrees Celsius).

"If it gets into room temperature in some materials, then there would be prospects for some programs," said MIT chemist researcher Keith Nelson, Live Science, adding that this is the highest temperature that such behavior has seen. [The 1

8 Biggest Unsolved Mysteries in Physics]

Scientists have described a "normal" heat movement using a heated kettle – the heat energy is coupled to the air molecules when the burner is switched off. process. These molecules stand in all directions; some of these molecules are scattered back into the kettle. Over time, the kettle water and the environment reach a balance at the same temperature.

In solid materials, molecules do not move because atoms are locked. "What can move is sound waves," said Nelson, who with Live Science co-author Gang Chen, a mechanical engineer at MIT

. Phonons can bounce and scatter, carrying heat-like molecules from the kettle. [What’s That Noise? 11 Strange and Mysterious Sounds on Earth]

This is not what happened in this new experiment

Previous Chen's theoretical work predicted that heat can move like a wave when moving through graphite or graphene. To test this, MIT scientists cross two laser beams through their graphite surface, creating what is called a disturbance model with parallel light lines and light. This has created the same graphite surface model for heated and unheated areas. Then they set another laser beam to see what happened when it reached graphite.

"Generally, heat gradually flows from heated regions to unheated regions until the temperature is washed," said Nelson. "Instead, the heat flowed from heated to unheated regions and had to flow even after the temperature was leveled everywhere, so the unheated regions were actually warmer than the regions that were originally heated." Meanwhile, heated regions have become even cooler than heated regions. And everything went smell fast – about the same speed that sound usually travels to graphite. [8 Ways You Can See Einstein’s Theory of Relativity in Real Life]

"The heat flowed much faster because it was moving without waves," Nelson Live Science said.

How did they get this strange behavior that scientists call "second sound",

"From a basic perspective, this is not just normal behavior. The second sound was measured only in a handful of materials, at any time, at any temperature. "Nelson said."

That's what they think is happening: graphite or 3D material has a layered structure in which thin carbon layers hardly know another, and so they behave like graphene, which is a 2D material. Because of what Nelson calls "small dimension", one of the phonons with a graphite layer is much less likely to remember and disperse other layers. In addition, phonons that can form graphite have wavelengths that are too large to reflect backwards after the grid gap, a phenomenon called feedback. These small audio packages scatter a little, but usually travel in one direction, which means they can travel on a long distance on average. Editor's Note: This article has been updated to clarify some of the experimental techniques and the fact that the heat is traveling at about the same rate so that sound moves through the graphite rather than the air, as previously mentioned. 19659009 Originally published in Live Science .


Source link