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Re: [Phys-l] Arrow of Time Issue



Another way of saying the same thing. The second law of thermodynamics says that the entropy of isolated systems "does not decrease with time." If we discovered in experiments that the entropy of isolated systems "decreases with time," it would mean that the second law of thermodynamics is wrong, NOT that time is running backwards.

John Mallinckrodt
Cal Poly Pomona

On Mar 7, 2012, at 7:27 PM, Jack Uretsky wrote:

I don't understand you. Let me try to explain why in two ways:
"If time is increasing" suggests that "time" is defined in such a
way that it could be non increasing. "Time" is not so defined. We define
"time" by findng a periodic phenomenum, and then counting periods. The
count always increases - by definition. "If time is increasing" is
logically like saying "if four is greater than three". But four is
defined as three plus one. So the "if" in the statement is surplusage;
there is no laternate possibility. Same with "time". We define it so
that there is no alternate possibility.
Regards,
Jack

"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley




On Wed, 7 Mar 2012, Bennett Sessa wrote:

That is my understanding. If time is increasing then entropy must always increase. If time decreases Clausius equality and the entropy equation show that entropy should decrease, but we know this to be impossible, therefore time cannot decrease. CPT symmetry shows that time is however reversible.



On Mar 6, 2012, at 9:52 PM, Jack Uretsky <jlu@hep.anl.gov> wrote:

Hi Bennet-
I'm not sure I understand your argument.
As I see it, "time:" by definitiion, can only "go forward", so
that gives a meaning to the phrase "go forward". So the statement that
entropy can only increase, means to me that: as iime increases, entropy
increases. Do you have a different understanding?
Regards,,
Jack

"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley




On Tue, 6 Mar 2012, Bennett Sessa wrote:

The second law of thermodynamics says that entropy must always increase or remain constant, therefore time must always increase (go forwards). CPT symmetry says that charge, parity, and time are all reversible, therefore time can travel forwards and backwards. We have experimental data showing both to be true, yet have no idea how thy are related.



On Mar 6, 2012, at 9:28 PM, Jack Uretsky <jlu@hep.anl.gov> wrote:

Hi Bennet-
I would like to hear (see) your descriptiion of the so-called
"dispute". This is my appreciation of your posting.
Regards,
Jack Uretsky

"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley




On Tue, 6 Mar 2012, Bennett Sessa wrote:

This is my first time posting in Phys-l, C.V. Britton recommended I join. I am 13 years old and have a knowledge of everything from calculus I up to some differential equations. In my spare time I solve equations and teach myself new principles on the whiteboard I have in my room. I have been researching physics for a few years now.

I believe I have a plausible solution to the dispute between CPT symmetry and the second law of thermodynamics. I believe time to be a conservative, connected, four-vector quantity and the quintessence (dark energy) to be the scalar quantity. In short I would be trying to find some sort of Lagrangian to describe the vector potential of time, therefore describing the laplacian which should be equal to zero if the field is irrotational.
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