Thread: Thermodynamics discoveries.

Can anybody tell me how the First and second laws of thermodynamics were proposed and how were they accepted?
My doubt is regarding to their validity on all scales of the 'system' in thermodynamics. How do we know whether the total energy content of the universe remains constant? or whether is entropy always increases?

Please help.

If you consider the Universe to be a closed system then we have no reason to expect that the laws of thermodynamics would not apply, since empirical evidence has never shown them to be wrong in smaller systems.

There is some speculation (and a story by A.C.Clarke) that considers energy transfers from other universes, but that merely changes the limits of the closed system.

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If you are interested in the history of these laws, see the Wiki article here:
http://en.wikipedia.org/wiki/Laws_of_thermodynamics.

Understand that the Laws of Thermodynamics are considered fundamental laws of the universe. As such, they can only be discovered, not derived nor proven. We accept that they are correct because all known phenomena obey the Laws, and we have never found a case that violates the Law.

It is still possible that the Laws of Thermodynamics may be 'wrong,' or at least, subject to modification. This is what happened to Newton's laws and to John Dalton's atomic hypothesis, for example. It is simply a matter of new discoveries.

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Originally Posted by SteveF

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If you are interested in the history of these laws, see the Wiki article here:
http://en.wikipedia.org/wiki/Laws_of_thermodynamics.

Understand that the Laws of Thermodynamics are considered fundamental laws of the universe. As such, they can only be discovered, not derived nor proven. We accept that they are correct because all known phenomena obey the Laws, and we have never found a case that violates the Law.

It is still possible that the Laws of Thermodynamics may be 'wrong,' or at least, subject to modification. This is what happened to Newton's laws and to John Dalton's atomic hypothesis, for example. It is simply a matter of new discoveries.

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Thank God I never took those seriously.

Sincerely,


William McCormick

Originally Posted by SteveF

If you are interested in the history of these laws, see the Wiki article here:
http://en.wikipedia.org/wiki/Laws_of_thermodynamics.

Understand that the Laws of Thermodynamics are considered fundamental laws of the universe. As such, they can only be discovered, not derived nor proven. We accept that they are correct because all known phenomena obey the Laws, and we have never found a case that violates the Law.

It is still possible that the Laws of Thermodynamics may be 'wrong,' or at least, subject to modification. This is what happened to Newton's laws and to John Dalton's atomic hypothesis, for example. It is simply a matter of new discoveries.

Thanks for the link, However, I feel that if the laws were not proven, they should be considered as simply postulates. The same goes with relativity. Since Einstein didn't prove it mathematically, it stopped short of being called a Law, but only a Theory. But all experimental data seems to agree with its results.

Originally Posted by Bunbury

If you consider the Universe to be a closed system then we have no reason to expect that the laws of thermodynamics would not apply, since empirical evidence has never shown them to be wrong in smaller systems.

There is some speculation (and a story by A.C.Clarke) that considers energy transfers from other universes, but that merely changes the limits of the closed system.

How if, I consider a cluster of galaxies s my system, and the rest of the whole universe as my surrounding. 1st Law says that total energy content of (system+surroundings) must remain constant. 2nd Law states that no matter what, the entropy of the universe always increases.

Tell me, how can you say they are correct? may be the late Arthur C. Clarke was right, how are we gonna know?