Thermodynamics and The Universe

What is quantum energy?

If I recall correctly.....The differences are mostly physical rather than conceptual.You'd still experience time, the way you usually do. That is, you'd have a past and a future in a linear fashion.A few differences are:
1. All particles would decay much faster, from your point of view. Even those that normally would not decay
2. Very interestingly, science itself would be difficult in such a universe, as most of the equations of motion are what is called ultra-hyperbolic. Usually in physics we solve an equation which models a system and use the values we measure in the present to determine the future.
i.e. Solution + Current conditions => Future conditionsThis can't be done when there are 2 temporal dimensions. So science itself would be difficult in such a world.3. Matter tends to be repulsive to all other matter, even gravity wouldn't overcome this repulsion in most cases. This repulsion has the dramatic effect of making other matter "disappear" out of the universe from your point of view. In fact in such a world, most particles would think they're the only thing around.Of course I've mainly concentrated on the effects coming from having 2 time dimensions. There is also effects from there being only 2 spatial dimensions, but they're not as interesting.

I thought that might have been what you meant.
If the system is a single Qauntum Mechanical particle the correct term is "ground state energy".
If the system is a Quantum Field, the term is the "vaccum state".Not that it matters, just thought you might want to know.

You just change a sign in the metric, the object that describes how distances work in spacetime, and it all follows (after a little while). Points 2 and 3 in the list above are almost immediately obvious after you do this.It's often interesting to tweak things a bit and see what stuff "could" have been like.

Yeah, literally. It's a interesting look at how PDEs behave in alternative metrics, plus it shows you how special 3 + 1 is. A paper by Tegmark, I think, kind of said most of what has been said so far.
It's not researched or anything really, most of the main results can be shown on a few A4 sheets.

Well the idea of two time dimensions,(outside F-theory, I don't know String Theory so I don't understand it in that context) I would have thought is just kind of an interesting look at what happens to SR and Particle interactions when you change a few things. I think somebody would be going out on a limb if they started talking about life in such a place.Plus, it isn't a cosmological model. There would be no coherent way of saying those other worlds exist, all you can say is "This is what a world with Special Relativity left intact, but with another time dimension would look like".
This is the way I would have understoof it in a purely SR and simple particle physics stuff.However, Tegmark doesn't do this the way I'm familiar with it. He actually uses String Theory, so I can't really comment on his paper.
Although he still seems to say the same basic consequences.Except to say: The Anthropic Principle hasn't got anything to do with intelligent design, in fact it's a lazy link to make. I think Tegmark's just saying why String Theorists might not have to explain 3+1 dimensionality. The Anthropic Principle is sort of a modification to the Copernican Principle.
i.e., Your position isn't special, up to the fact of your existence.Anyway I should probably stop talking about this, Tegmark's paper is a mix of stuff I know and stuff I don't.I only ever heard of the paper (wasn't on arxiv and I never specifically wanted it, so I didn't go through Quantum & Classical Gravity), so thanks for the link.Edited by Son Goku, : Additions

I don't know. I should probably make clear that I was saying that the linear conception of time is still there to a single observer. That is they have a time orientable worldline.
The reason I pointed it out is that alot of people, when they hear of two time dimensions, initially think that instead of having a timeline, you'd have a "time area", if you catch my drift. Really? How so?

How does QM go against the Laws of Thermodynamics?In fact the third law, Entropy tends to zero as temperture tends to zero kelvin (Which has the immediate consequence that specific heat decreases as you lower temperture), can only be explained by Quantum Mechanics.I don't understand how QM contradicts thermodynamics, when you derive the third law using QM.As for the Zeroth Law, "If two systems are in thermal equilibrium with a third, they are also in thermal equilibrium with each other." That is unaltered.The First Law:
"An equilibrium macrostate of a system can be characterized by a quantity E(called internal energy) which has the property that for an isolated system,
E= constant

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If the system is allowed to interact and thus goes from one macrostate to another, the resulting change in E can be written in the form:
E = -W + Q

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where W is the macroscopic work done by the system as a result of the system's change in external parameters. The quantity Q being defined by the above relation, is called the "heat absorbed by the system".

On a cursory examination you would expect QM not to make to much of a difference, since the definition makes heavy use of the word macrostate. In fact it doesn't. I can give a detailed explanation of why it does not.The Second Law:
An equilibrium macrostate of a system can be characterized by a quantity S (called entropy), which has the properties that:
(a)In a nay process in which a thermal isolated system goes from one macrostate to another, the entropy tends to increase, i.e.,
S >= 0

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(b)If the system is not isolated and undergoes a quasi-static infintesimal process in which it absorbs heat Q, then:

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dS = Q/T

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where T is a quantity characteristic of the macrostate of the system. (T is called the "absolute temperture" of the system.)Again heavy use of the word macrostate, implying that this is a statement about the dynamics of bulk systems. Again something QM doesn't modify.I fail to see how QM undermines the laws of thermodynamics if it leaves three of them unchanged and is used to derive the third.All definitions taken from Federick Reif "Fundamentals of Statistical and Thermal Physics" (1965).

I still don't understand how QM undermines thermodynamics. I appreciate what you're saying about it running counter to intuition, but I fail to see its conflict with Thermodynamics. People disagree on the explanation of the measurement problem (most now think decoherence is the resolution to the problem), but this is a marginal part of QM, in the sense of the pragmatics of the subject, which isn't studied outright in most places. It has very little to do with how good QM is as a physical theory. The third law was never explained using Classical Mechanics. One could notice it as a condition on the Specific Heat as you reduced the temperature in an experiment, but an explanation doesn't come until you encounter QM's lack of a continuum of energies. The third law isn't that intuitive on the every day level. Sure, even the existence of absolute zero, which the third law pertains to, isn't obvious at all.

Okay, I see what you are saying here. I'll deal with this, but first may I ask you a question relating to the following quote: You are saying there is some conclusion coming from Quantum Mechanics that conflicts with some basic Thermodynamic observation the layman makes.Am I correct in my assessment of what you're saying?
If I am, what is the troublesome conclusion from QM and what Thermodynamical observation does it conflict with?

Do you realise that calculating the entropy of the Earth and the Entropy of Venus would be an almost impossible task. Entropy is related to how many different microstates an object could have, while still maintaining the same macrostate. For both Earth and Venus, let's say, the amount of macroscopically similar microstates would be equally enormous in both cases.
The surface of the Earth probably would have a lower entropy than surfaces on other bodies throughout the rest of the Sol system. However I don't know how much lower. It'd be a very difficult thing to guess.
The main point is nobody has ever measured or even guessed at the total entropy of the Earth.However QM doesn't try to explain how Earth has lower surface entropy than other bodies in the Sol System. I'm not being purposefully difficult, but I still don't understand why your focusing on QM here. QM deals with dynamics below the 10^-10 meters mark (roughly, there are superconductors e.t.c.).
Anybody who'd try to use QM to explain Earth's lower surface entropy.....Well to be honest, I wouldn't know where they'd start, what they'd do, or why they'd be doing it.Can I ask why you think QM purports to explain Earth's Entropy?
Did some news article say it?
(Sorry, you have to understand using QM to explain Earth's entropy would be bizarre. What kind of Byzantine wavefunction would handle that?)Edited by Son Goku, : More precise.

What do you think Entropy is? Also where are the figures for the entropy coming from?Remember S = k ln(Omega), which would be almost incalcuable for a planet.Also what has QM got to do with calculating the classical entropy (i.e. entropy in the way Boltzmann percieved it) of a classical object?You seem to be saying that QM is used to airbrush out Earth's lower entropy, however I still don't see why.

Remember entropy is not fundamentally related to disorder. There are many cases where one can have two systems, the most disorderly of which actually has lower entropy than the ordered one.
Also the measure of entropy, as originally conceived by Boltzmann, depends on exactly where you draw your macro/microstate boundary.Entropy is more a measure of how generic a macrostate is. However a lot of "disordered" states are very generic and hence the link.

Yes, spectroscopy, which can penetrate into their upper mantle shows that they do. Plus you've the fact fusion reactors do this generically.
If stars couldn't form the heavier elements, everything we know about the weak force would be wrong. (And CERN shows that probably isn't the case) Yeah, all the way back since the 80s. We've even seen the stellar core ignite. I think Hubble's observations between 1994-1996 are particularly good for this. Although I'm no expert.Also when you have a collapsed star versus the hydrogen cloud that formed it, the star has a much, much larger entropy value than the cloud. This is probably the clearest example of why entropy isn't disorder.
I can explain if further clarification is required.