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Name:  Vito
Status:  student
Age:  13
Location: N/A
Country: N/A
Date: 2000-2001


Question:
I think that there is a limit to how much heat something can have. This is because the speed limit of the universe is the speed of light. What i am trying to say is that the atoms in matter can only speed up their vibration until they reach the speed of light at which then the matter must stay at that temperature it is at.

Is this true?


Replies:
There is an upper limit to the temperature of an atom, but not for the reason you give.

The speed of light doesn't limit energy absorption. When objects start moving close to the speed of light, Einstein's Theory of Special Relativity comes into play. As an object approaches the speed of light, it seems to get heavier. Experiments show that an infinite amount of energy is required to boost an atom to the speed of light. An object with infinite energy could be an infinite temperature.

The actual limit is related to stars. When a solid gets hot enough, it melts into a liquid. When a liquid gets hot enough, it boils into a gas. When a gas (freely moving molecules) gets hot enough, the molecules break into individual atoms. When atoms get hot enough, they break into individual protons, neutrons, and electrons. This is called a plasma. This is the material within a young star, like the sun. When these particles are hot enough, they put out energy much faster than anyone could ever put it in. This release of energy is what we call sunlight.

Kenneth Mellendorf


Heat is a form of kinetic energy so basically you are saying that there is a limit to how much energy due to motion an atom can have. Relativity limits the top speed to the speed of light in vacuum but the kinetic energy also depends on the mass of the atom. Relativity says, and it has been demonstrated to be true, that at speeds near the speed of light the mass starts to increase. Because there is no limit on the mass there is no limit to the amount of energy you can put into the system (assuming you have some way of putting it in).

Greg Bradburn


Not quite. As the speed of an object gets closer and closer to the speed of light, its mass increases. If an object could travel at the speed of light, its mass would be infinite. So, there is not upper limit to the amount of kinetic energy an object can have, even though there is an upper limit to its speed. Temperature is a measure of average molecular kinetic energy, so there is consequently no upper limit to temperature, either.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois



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