Does the conservation law prove that energy is eternal?

In summary, the first law of thermodynamics is often used to claim that energy/matter must always exist and have no beginning or end. However, this idea is not proven to hold globally in General Relativity and there are processes in cosmology that do not obey this law. The Many World's Interpretation of Quantum Mechanics, which suggests that the universe splits into different realities with each random quantum event, is a popular but contentious theory among physicists. It raises questions about whether energy conservation is violated in this scenario and if it would lead to an infinite number of universes. However, the interpretation itself may be influenced by faulty metaphysical principles and is not universally accepted among professionals.
  • #1
8LAK
2
0
I've heard many people claim that the first law of thermodynamics proves that the energy/matter must always exist in some form or another, since it cannot be created or destroyed. This would mean that energy/matter had no beginning, and will have no end. Is this a valid claim? Or is there something I'm misunderstand about the conservation law?

And while I'm on the subject, I'd like to ask a few semi-related questions about the Many World's Interpretation of Quantum Mechanics. From what I understand, the MWI says that the random events of quantum mechanics "splits" the universe into different realities, one with each respective outcome of the random quantum event. My questions are:

1. Do physicists take the MWI seriously? Or is it just an imaginative hypothesis that probably isn't true?

2. Would the "universe splitting" of the MWI violate the energy conservation? Does it really create a new universe for each random outcome?

3. If the MWI is in fact true, could we then conclude that there exists an infinite amount of universes? Would it be true infinity, or just a really large number?

Thanks.
 
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  • #2
8LAK said:
I've heard many people claim that the first law of thermodynamics proves that the energy/matter must always exist in some form or another, since it cannot be created or destroyed. This would mean that energy/matter had no beginning, and will have no end. Is this a valid claim? Or is there something I'm misunderstand about the conservation law?
...

The idea of energy conservation is questionable outside of the situations where it can be applied in a mathematically rigorous way. We think the universe is governed largescale by General Relativity. Energy conservation is not proven to hold globally in GR.

If you can isolate a subsystem, enclose something in a box, and give meaning to all the relevant types of energy in the box, then you can apply the law. But on large scale in cosmology there are processes which apparently to not obey the local restricted law. Yet they are accepted by the community because they agree with observation and because there is no logical reason to suppose that energy conservation is true for the system as a whole.

There is an FAQ about this that people recommend sometimes. Maybe someone will offer URLs. I realize this is a vague unsatisfactory answer. There are plenty of unanswered questions in science and maybe this is one. Wish I could be more helpful. Good luck pursuing this!
 
  • #4
=marcus;2314742]The idea of energy conservation is questionable outside of the situations where it can be applied in a mathematically rigorous way. We think the universe is governed largescale by General Relativity. Energy conservation is not proven to hold globally in GR.

Hi Just a clarification. Does this mean it has been proven not to hold?? Or that within the mathematical structure it is not an inevitable neccessity??

If
you can isolate a subsystem, enclose something in a box, and give meaning to all the relevant types of energy in the box, then you can apply the law. But on large scale in cosmology there are processes which apparently to not obey the local restricted law. Yet they are accepted by the community because they agree with observation and because there is no logical reason to suppose that energy conservation is true for the system as a whole
.

Is this in regard to the apparent motion or related to the energy loss through expansion and photon frequency reduction?? Other?


Thanks
 
  • #5
Austin0 said:
Hi Just a clarification. Does this mean it has been proven not to hold?? Or that within the mathematical structure it is not an inevitable neccessity??
It holds only in special cases.

Austin0 said:
Is this in regard to the apparent motion or related to the energy loss through expansion and photon frequency reduction?? Other?
That's one way of looking at it. In general, though, it stems from Noether's theorem, where we find that energy conservation comes about if certain properties of the system are independent of time. In this case, energy will be conserved within General Relativity if we have a space-time geometry that is independent of time.

This is a problematic statement in GR, however, as a space-time geometry that is independent of time for one observer will not be independent of time for some other observers. But in any case energy won't be conserved in an expanding universe because of the expansion.
 
  • #6
Chalnoth said:
But in any case energy won't be conserved in an expanding universe because of the expansion.

What do you mean here? Do you say this because of dark energy/cosmological constant? Accelerated expansion?

The old style inertial expansion assumption was a closed system description wasn't it?

*****

On the general issue raised by 8lak, MWI is a surprisingly popular interpretation of QM among professionals. There are those who say it is the only choice left to them.

But its radical violation of energy conservation is only one of its many obvious holes. I have always taken MWI as evidence that it is faulty metaphysical principles which have led to such a patently unnatural view of quantum cosmology.
 
  • #7
apeiron said:
What do you mean here? Do you say this because of dark energy/cosmological constant? Accelerated expansion?
Any form of matter that experiences pressure will experience a change in energy per comoving volume due to expansion. Normal and dark matter are generally considered pressureless, and so don't factor into this at late times. But photons have pressure, as do dark energy and the inflaton field. And they therefore do change in energy per comoving volume.

Edit: I should mention that this does depend upon what you mean by "energy". If you include gravitational potential energy into the mix, then energy is always conserved in GR by definition. With dark energy and inflation the increase in energy in the dark energy/inflaton field is understood as coming from an increase in negative gravitational potential energy, just as with the perhaps more understandable case of two rocks falling towards one another (if they start at rest far away, then their kinetic energy is zero and potential energy nearly so. As they fall towards one another, their kinetic energy increases, and their potential energy also increases in the negative direction, leaving the sum constant).

apeiron said:
On the general issue raised by 8lak, MWI is a surprisingly popular interpretation of QM among professionals. There are those who say it is the only choice left to them.

But its radical violation of energy conservation is only one of its many obvious holes. I have always taken MWI as evidence that it is faulty metaphysical principles which have led to such a patently unnatural view of quantum cosmology.
It's not a radical violation of energy conservation, though. There is nothing "new" being created when two worlds in the many worlds interpretation diverge. You just have different components of the same wavefunction that don't interfere effectively with one another any more. They're still components of the same wavefunction, so there's no additional energy.
 
  • #8
Chalnoth said:
If you include gravitational potential energy into the mix, then energy is always conserved in GR by definition.
.

Thanks. Good explanation.

Chalnoth said:
It's not a radical violation of energy conservation, though. There is nothing "new" being created when two worlds in the many worlds interpretation diverge. You just have different components of the same wavefunction that don't interfere effectively with one another any more. They're still components of the same wavefunction, so there's no additional energy.

Naively, a whole new world full of stuff appears "somewhere", even if in some QM configuration space or Hilbert-verse.

But this would the view that would come from taking QM as essentially an open thermodynamic story? Uncertainty would be something that can be endlessly borrowed from?
 
  • #9
apeiron said:
Naively, a whole new world full of stuff appears "somewhere", even if in some QM configuration space or Hilbert-verse.

But this would the view that would come from taking QM as essentially an open thermodynamic story? Uncertainty would be something that can be endlessly borrowed from?
Well, again, there's no new energy being created. This should be most clear if one considers that the number of components of the wavefunction that describe a given system actually are somewhat arbitrary: it depends upon what representation you are talking about.

Because the number of components of the wavefunction depends upon what you take the wavefunction in terms of, it wouldn't ever make any sense for there to be conservation of a sum of some physical quantity over the many wavefunction components: the sum would vary just by changing the representation!

Instead, there are two operations in quantum mechanics that correspond to determining the energy. One is to ask the question, "What is the expected value of the energy?" and the other is to ask, "If I make a measurement of energy, what value will the measurement produce?" In the first case, you take a weighted average over the many components, not a sum. In the second, the outcome of your measurement will be one of the components of the wavefunction with a probability given by the square of its amplitude.

So instead of thinking of it as a 'whole new world full of stuff,' perhaps a better way of thinking of it is as just a different configuration of our world coexisting with ours, rather like how an electron can be in two states at once.
 
  • #10
Chalnoth said:
So instead of thinking of it as a 'whole new world full of stuff,' perhaps a better way of thinking of it is as just a different configuration of our world coexisting with ours, rather like how an electron can be in two states at once.

So in thermodynamic terms, the same ensemble of microstates in different configurations. And if we are counting just microstates, then everything looks conserved.

This is either bogus or subtle. :smile:

I guess I am reacting against it because I take the enlarged thermodynamic view where there is top-down causality, global constraints, etc. So that is the framework I'm trying to fit this into.

In this light, I would still feel that the QM uncertainty is like a bottomless well. Then the questions you say are asked - "What is the expected value of the energy?", "If I make a measurement of energy, what value will the measurement produce?" - are the kind of top-down constraints which closes matters to produce the coherence of a "GR system".

Not asking you to agree but you have helped sharpen up the questions for me.
 
  • #11
apeiron said:
So in thermodynamic terms, the same ensemble of microstates in different configurations. And if we are counting just microstates, then everything looks conserved.
It's not that everything looks conserved, but it actually is.

apeiron said:
I guess I am reacting against it because I take the enlarged thermodynamic view where there is top-down causality, global constraints, etc. So that is the framework I'm trying to fit this into.
I don't know what you mean by "top-down causality" or "global constraints", but in any case, there is nothing about quantum mechanics that in any way contradicts thermodynamics. Thermodynamics had to be modified somewhat to accord with the statistical properties of quantum mechanics, but for the most part that's a small effect (it has some interesting consequences like superfluidity and superconductivity, but it doesn't affect the overall picture of thermodynamics).

apeiron said:
So in thermodynamic terms, the same ensemble of microstates in different configurations. And if we are counting just microstates, then everything looks conserved.
It's not that everything looks conserved, but it actually is.

apeiron said:
In this light, I would still feel that the QM uncertainty is like a bottomless well.
A bottomless well in what sense?
 
  • #12
Chalnoth said:
A bottomless well in what sense?

As naked potential, it would be infinite.

Chalnoth said:
It's not that everything looks conserved, but it actually is.

Yes, but in a systems perspective the "everything" also includes the macrostate, so to speak. In conventional views, a system just is the sum of its microstates (a macrostate emerges "for free"). In a systems view - arguably - the macrostate is causally active, a source of action or "energy", and so its cost must be counted as well.

In this line of thought, many worlds seem a violation of conservation as macrostates are being freely created (even if microstates are conserved).

It is like if we were talking about the usual ideal gas model. Conventional approach is to take the flask that contains the gas as read. The thermodynamics is the collection of microstates inside. But in a wider view - as would have to be taken in cosmology - we then have to factor in the issue of who made and paid for the flask, the boundary conditions.

MWI would be like saying you can make new and differently shaped flasks freely.
 
  • #13
apeiron said:
As naked potential, it would be infinite.
Yes, but infinite in what sense?

apeiron said:
Yes, but in a systems perspective the "everything" also includes the macrostate, so to speak. In conventional views, a system just is the sum of its microstates (a macrostate emerges "for free"). In a systems view - arguably - the macrostate is causally active, a source of action or "energy", and so its cost must be counted as well.
Fine, but the many worlds of the MWI would be a superposition of different macrostates, not wholly different entities.

apeiron said:
MWI would be like saying you can make new and differently shaped flasks freely.
No, it's just saying that it isn't any problem to have a superposition of two different states of the same flask, and there is also the possibility that the interference between those states may be low enough that information isn't communicated between them at any meaningful level.
 
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  • #14
Chalnoth said:
Yes, but infinite in what sense?

Unlimited or boundless would be better terms in my book.

Regular notions of infinity would rely on the image of infinite extension - keep on adding forever. But I am thinking more in terms of the magic pudding - the infinitely divisible.

http://en.wikipedia.org/wiki/The_Magic_Pudding

Chalnoth said:
No, it's just saying that it isn't any problem to have a superposition of two different states of the same flask, and there is also the possibility that the interference between those states may be low enough that information isn't communicated between them.

Here I don't see how it is legitimate to treat a superposition as an actual macrostate. The superposition has to be decohered to be a definite something. A superposition is the before, not the after.

I can see that you are arguing that all that is happening is a multiplication of the complexity of the superposition state to become an ever more massive MWI agglomeration. And it would be correct in so far as the formalisms of QM superposition are concerned.

But the big QM issue here is the placing of the epistemic cut, the collapse of superposed states. And the MWI just ducks the issue by saying it never has to happen. There is no place the critical questions you mention actually get asked.

Edit: Although the escape clause may be that, as you say, the presumption a lack of interference and so a quasi-separation of some kind. Yet this too must be vulnerable to the criticism it is unrealistic when it looks collapse does generally happen at quite small scales.
 
  • #15
apeiron said:
Unlimited or boundless would be better terms in my book.

Regular notions of infinity would rely on the image of infinite extension - keep on adding forever. But I am thinking more in terms of the magic pudding - the infinitely divisible.

http://en.wikipedia.org/wiki/The_Magic_Pudding
Except it's nothing like that. As I've been saying, nothing "new" is being created.

apeiron said:
Here I don't see how it is legitimate to treat a superposition as an actual macrostate. The superposition has to be decohered to be a definite something. A superposition is the before, not the after.
I think you're confusing the MWI interpretation with other interpretations that have wave function collapse. In the MWI, there is no collapse at all. There is only the appearance of collapse. The system is always in a superposition of many states. It's just that if certain interactions have occurred, then the different elements of the superposition cannot communicate effectively. That is all.

As for it not being legitimate to treat it as a macrostate in the thermodynamic sense, well, that's fine. A macrostate in thermodynamics is the set of macroscopic variables that are needed to fully-describe the macroscopic behavior of the system. Because different components of the wavefunction aren't observable in macroscopic systems, they don't belong in a consideration of thermodynamic macrostates. This doesn't mean that the MWI is wrong, just that the word "macrostate" is a poor word to use to describe the entire ensemble of configurations of the system.

apeiron said:
But the big QM issue here is the placing of the epistemic cut, the collapse of superposed states. And the MWI just ducks the issue by saying it never has to happen. There is no place the critical questions you mention actually get asked.
That's not ducking the issue. It's solving the problem of wavefunction collapse in an extraordinarily simple and elegant manner. And given the difficulty in demonstrating precisely how the appearance of collapse arises from the MWI, I would consider a claim that it's "ducking the issue" to be an admission of ignorance of the difficulties involved.

apeiron said:
Edit: Although the escape clause may be that, as you say, the presumption a lack of interference and so a quasi-separation of some kind. Yet this too must be vulnerable to the criticism it is unrealistic when it looks collapse does generally happen at quite small scales.
And at small scales you can actually calculate how effective the collapse should be, and therefore compare the prediction of the MWI against observation. So far observations match the predictions.
 
  • #16
8LAK said:
I've heard many people claim that the first law of thermodynamics proves that the energy/matter must always exist in some form or another, since it cannot be created or destroyed. This would mean that energy/matter had no beginning, and will have no end. Is this a valid claim? Or is there something I'm misunderstand about the conservation law?

Conservation laws are assumed. They cannot prove anything since it is impossible to verify a scientific theory (you can only prove it wrong, not right). Conservation laws, or symmetry, are about the last assumption we will throw out in developing theories in physics. They are too central to our dependence on the belief that things should exist and be describable in rational intelligible terms. Ex nihilo nihil fit. Nothing comes from nothing.

Of course, assuming conservation laws, something will always exist and something has always existed. But this argument is circular. Welcome to philosophy :smile:. It's all about the assumptions, and sometimes the higher level theories (QM, thermodynamics) can just be obfuscating noise.
 
  • #17
kote said:
Conservation laws are assumed.
And then tested and verified. They aren't simply assumed by fiat, but people actually go out and test to see whether or not they are true.

Of course, one cannot prove in a strict, mathematical sense that a conservation law always holds. But one can place reasonable limits upon them.
 
  • #18
Chalnoth said:
And then tested and verified. They aren't simply assumed by fiat, but people actually go out and test to see whether or not they are true.

Of course, one cannot prove in a strict, mathematical sense that a conservation law always holds. But one can place reasonable limits upon them.

Of course there is a strong basis for the assumption, which I mentioned. I don't agree that laws can be tested for truth or that they can be verified. Those ideas fly in the face of Popper's generally accepted notion of falsifiability. In science we do falsification, not verification. It seems that you just said that though, so I'm not sure there's any real disagreement.
 
  • #19
kote said:
Of course there is a strong basis for the assumption, which I mentioned. I don't agree that laws can be tested for truth or that they can be verified. Those ideas fly in the face of Popper's generally accepted notion of falsifiability. In science we do falsification, not verification. It seems that you just said that though, so I'm not sure there's any real disagreement.
Er, what? One of the major goals of modern high-energy experimental physics is to show that certain symmetries (from which conservation laws can be derived) are only approximations to the true behavior. That the left-right symmetry is broken was one of the major discoveries that lead to the nature of the weak nuclear force, for instance.
 
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  • #20
Chalnoth said:
Er, what? One of the major goals of modern high-energy experimental physics is to show that certain symmetries (from which conservation laws can be derived) are only approximations to the true behavior. That the left-right symmetry is broken was one of the major discoveries that lead to the nature of the weak nuclear force, for instance.

It's still assumed that there is some better, underlying, symmetric explanation. E=mc^2 didn't break symmetry, it expanded it. We are always assuming an underlying symmetry - we can't describe causation (natural law) without it.
 
  • #21
kote said:
It's still assumed that there is some better, underlying, symmetric explanation. E=mc^2 didn't break symmetry, it expanded it. We are always assuming an underlying symmetry - we can't describe causation (natural law) without it.
That's only because symmetries have proven an exceedingly useful way of thinking about the behavior of the universe. If, in time, some other way of thinking about the universe turns out to be a more useful way of interpreting the evidence, then we will drop all this talk about symmetries and move onto that instead.

Just because we don't yet know how to describe the behavior of the universe without symmetries doesn't mean that we assume them by fiat. It just means that we haven't yet discovered a better theory of the behavior of the universe without them.

Now, given the incredible usefulness of symmetries, it is my suspicion that there exist some very fundamental symmetries to our universe. But there's no reason for me to hold fast to that belief against evidence, were evidence to start to appear in some other direction.
 
  • #22
Chalnoth said:
Now, given the incredible usefulness of symmetries, it is my suspicion that there exist some very fundamental symmetries to our universe. But there's no reason for me to hold fast to that belief against evidence, were evidence to start to appear in some other direction.

The thing is, we define objective reality through symmetries. You wouldn't know evidence for asymmetrical laws of nature if you saw it... from Wigner, “if the correlations between events changed from day to day, and would be different for different points of space, it would be impossible to discover them.” Also:

It is widely agreed that there is a close connection between symmetry and objectivity, the starting point once again being provided by spacetime symmetries: the laws by means of which we describe the evolution of physical systems have an objective validity because they are the same for all observers. The old and natural idea that what is objective should not depend upon the particular perspective under which it is taken into consideration is thus reformulated in the following group-theoretical terms: what is objective is what is invariant with respect to the transformation group of reference frames, or, quoting Hermann Weyl (1952, p. 132), “objectivity means invariance with respect to the group of automorphisms [of space-time]”.[22] Debs and Redhead (2007) label as “invariantism” the view that “invariance under a specified group of automorphisms is both a necessary and sufficient condition for objectivity” (p. 60). They point out (p. 73, and see also p. 66) that there is a natural connection between “invariantism” and structural realism.

http://plato.stanford.edu/entries/symmetry-breaking/#5

If physics is in the business of describing objective reality, then it must assume causal symmetry. There's no other option.
 
  • #23
kote said:
Conservation laws, or symmetry, are about the last assumption we will throw out in developing theories in physics. .

Agreed that symmetry should be taken as the most basic concept - though locality and atomism have also been taken as the "fundamental" guiding image in earlier physics.

But then you have to ask what is "perfect symmetry"? Or the most generalised possible notion of symmetry? A rotation or a translation or a gauge symmetry are all just local examples of a more universal something.

Even "closed" symmetries are a particular family of symmetries.
 
  • #24
That doesn't strike me so much as an assumption as it is just a statement that it's always going to be possible to describe the world in terms of some symmetries. One can show, for instance, that it is possible to take purely random, time-variant laws of nature, and show that due to the ambiguity of the time coordinate, there exists a time-invariant way of describing the system:

http://arxiv.org/abs/0708.2743

I tend to expect that in a sense, then, the existence of some symmetries is an inevitability, just based upon how we approach understanding the world.

That said, physical theories don't just rest at the most basic of symmetries like time invariance. Hypothetical high-energy laws of physics typically consider all of physical law as stemming from some fundamental construct (particles, strings, what have you) that obey some very specific symmetries.

I don't think the most basic of symmetries are really an assumption so much as order we impose on the world by the way in which we describe it.
 
  • #25
kote said:
The thing is, we define objective reality through symmetries. You wouldn't know evidence for asymmetrical laws of nature if you saw it...

Again, it is hard to talk about symmetries and asymmetries unless you have really thought through the most general possible definitions.

For example, Chalnoth mentioned chiral symmetry-breaking. That would be an "asymmetry" across a single scale. Left and right, positive and negative - each direction is the same size still, even if only one route is taken.

But a more general asymmetry would be a breaking of symmetry over all scales. A fractal or scalefree breaking.

The causality of the universe, for example, is broken in this asymmetric fashion - the causal light cone story. And it is why time on the global scale looks to have just a single progressive direction, but on a local scale - that of individual events - appears to be symmetrically bi-directional.
 
  • #26
Chalnoth said:
I don't think the most basic of symmetries are really an assumption so much as order we impose on the world by the way in which we describe it.

Or alternatively, symmetry-breaking - the thermodynamic-like gradient from max symmetry to max asymmetry - could be actually the way worlds emerge via self-organisation.

The human brain does indeed dichotomise to impose order on experience. It's neural architecture is set up to break the chaos of impressions into figure and ground, focus and fringe, event and context, what and where, etc.

But this would be no coincidence. Brains have to employ self-organisation too. The same dynamics are at work for any "system", whether it be cosmological or neurological. So symmetry, symmetry-breaking, and asymmetry are deep concepts because they get at the deep causality of SO systems.
 

1. What is the conservation law and how does it relate to energy?

The conservation law states that energy cannot be created or destroyed, only transferred from one form to another. This means that the total amount of energy in a closed system remains constant. This law is closely related to the concept of energy in that it shows that energy is a fundamental and unchanging quantity in the universe.

2. Does the conservation law prove that energy is eternal?

No, the conservation law does not prove that energy is eternal. It simply states that energy cannot be created or destroyed, but it does not address the origins of energy or its ultimate fate. Some theories suggest that the universe will eventually reach a state of maximum entropy, where all energy is evenly distributed and no work can be done, which could be seen as the end of energy.

3. How does the conservation law apply to renewable energy sources?

The conservation law still applies to renewable energy sources, as they are not creating energy out of nothing. Instead, renewable energy sources harness energy from natural processes, such as sunlight, wind, or water, and convert it into usable forms. This does not violate the conservation law, as the total amount of energy remains constant.

4. Can energy be converted from one form to another without any loss?

No, energy cannot be converted from one form to another without any loss. This is due to the concept of entropy, which states that energy tends to disperse and become less organized over time. Therefore, some energy will always be lost in the form of heat or other forms of energy that are not usable.

5. How does the conservation law support the concept of sustainable energy?

The conservation law supports the concept of sustainable energy by emphasizing the need to use energy efficiently and to find renewable sources of energy. Since energy cannot be created or destroyed, it is important to conserve and wisely use the energy resources we have. Sustainable energy sources, such as solar, wind, and hydro power, align with the conservation law by utilizing existing energy without depleting it.

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