Expanding universe and quantum wavefunctions

In summary: This is due to the fact that the particles will be so far apart that they will no longer be able to share a common quantum state.
  • #1
durant35
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In a dark energy dominated universe, it seems that all the particles get away from each other and that the final state will be one with one or zero particles per horizon. This sounds very intuitive, but it is based on classical physics and GR. Particles have wavefunctions and this is whar confuses me in the context of expansion (and leaving the horizon). In the very far future, due to expansion particles will interact rarely and therefore there will be no decoherence really, all of the wavefunctions will spread. However, due to spreading, it would be possible that their wavefunctions interact and decohere again (paradoxically) or overlap and form something like a Bose Einstein condensate. Both options are of course strange so this serves rather as a reduction an absurdum. My real question is, quantum mechanically, what can we expect regarding the behavior of particles and their lack of interactions?

Does it make sense to call them particles or will they really be spread out wavefunctions?
If the final state is one of one particle per horizon, will the wavefunction of the particle cover all of the horizon?

Thanks for the patience.
 
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  • #2
durant35 said:
In a dark energy dominated universe, it seems that all the particles get away from each other and that the final state will be one with one or zero particles per horizon.

No, that's not correct. Bound objects, like tables, chairs, people, planets, stars, and even things like solar systems and galaxies, will continue to be bound; dark energy doesn't and can't break them apart into their constituent particles. You might be confusing the dark energy dominated scenario with the "Big Rip" scenario, which is driven by something called "phantom energy" that can rip apart bound systems (hence the name), but which has no evidence to support it.
 
  • #3
durant35 said:
In a dark energy dominated universe, it seems that all the particles get away from each other and that the final state will be one with one or zero particles per horizon.
By "final state", are you referring to thermodynamic equilibrium or "heat death" of the universe?
 
  • #4
stoomart said:
By "final state", are you referring to thermodynamic equilibrium or "heat death" of the universe?

Yes, I was wondering what will happen with wavefunctions of the particles in the dark energy dominated universe approaching heat death. Will they spread due to lack of interaction between particles or will they have some meaningful wavelength that stays constant because of dark energy?
 
  • #5
This thread reminds me, that several years ago, the priest of my high school, asked me if the universe had an origin and an end, because he was explaining the creation to the boys. I told him about the Big Bang and entropic death, and that I believed that this was so.

So he told me that it is very important. That it is very important that the universe had an origin and an end.
When I asked him why, he replied: because Buddhists do not think so ! (I don't know if he would not be a friend of Lemaitre)
I don't know why I remember this conversation often

*I edit because I try to correct grammar (I'm not native)
 
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  • #6
durant35 said:
Yes, I was wondering what will happen with wavefunctions of the particles in the dark energy dominated universe approaching heat death. Will they spread due to lack of interaction between particles or will they have some meaningful wavelength that stays constant because of dark energy?
I would expect the final state to be wave function collapse, @kimbyd could probably speak more to this.
 
  • #7
durant35 said:
it would be possible that their wavefunctions interact and decohere again (paradoxically) or overlap and form something like a Bose Einstein condensate
Just wondering, could you elaborate on what you were thinking with the Bose Einstein condensate?
 
  • #8
PeterDonis said:
Bound objects, like tables, chairs, people, planets, stars, and even things like solar systems and galaxies, will continue to be bound;

Asking a B question in an I thread - if something as bound as a black hole evaporates, how can anything else not? Won't any bound set of particles eventually disperse due to quantum effects?
 
  • #9
Grinkle said:
if something as bound as a black hole evaporates, how can anything else not?

Thinking of a black hole as "more bound" than other objects is not helpful here, since it's leading you to an incorrect inference. The reason black holes evaporate while other bound objects don't is that black holes have a horizon. An ordinary bound object does not. Quantum effects in the neighborhood of the horizon are what cause the evaporation, at least according to our best current understanding.

Grinkle said:
Won't any bound set of particles eventually disperse due to quantum effects?

Technically, yes, but not quite the way you might think--at least, according to the best guess we have right now, which might not be very good since we don't have a good theory of quantum gravity. According to that best guess, what will happen, on a long enough time scale, is that any bound object will eventually quantum tunnel into a black hole, and then the hole will evaporate. But we're talking really, really long time scales here--much longer than the time scale on which the accelerated expansion due to dark energy will take all objects not part of our local bound system beyond our cosmological horizon.
 
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  • #10
PeterDonis said:
But we're talking really, really long time scales here--much longer than the time scale on which the accelerated expansion due to dark energy will take all objects not part of our local bound system beyond our cosmological horizon.
And much longer than timescales where most of the objects in these systems will be ejected or fall into the central black hole. It is only relevant for the stuff that gets ejected, and then is isolated from everything else.
 
  • #11
PeterDonis said:
part of our local bound system

What is our local bound system considered to be in this context?

All the matter that is in the Milky Way? The Local Group? More? Something much less that may not include all the particles currently making up you and I?
 
  • #12
Grinkle said:
What is our local bound system considered to be in this context?

Possibly our Local Group of galaxies; possibly even the Virgo cluster, which I believe our Local Group is orbiting. The Milky Way at the very least.

Grinkle said:
Something much less that may not include all the particles currently making up you and I?

No, much, much more than that--see above. The only way this would be a possibility is if a "Big Rip" scenario is correct, and that is extremely unlikely according to our best current model and data.
 

1. What is the expanding universe theory?

The expanding universe theory states that the universe is continually expanding and getting larger. This theory is supported by observational evidence such as the redshift of distant galaxies and the cosmic microwave background radiation.

2. How does the expanding universe relate to quantum wavefunctions?

The expanding universe theory can be explained by quantum wavefunctions, which describe the behavior of subatomic particles. These wavefunctions can also be used to model the expansion of the universe, as they show how particles can exist in multiple states at once.

3. What is the significance of quantum wavefunctions in understanding the expanding universe?

Quantum wavefunctions play a crucial role in understanding the expanding universe as they provide a mathematical framework for describing the behavior of particles at a microscopic level. This allows scientists to make predictions and understand the behavior of the universe at a larger scale.

4. How does the expanding universe affect the behavior of quantum wavefunctions?

The expanding universe has a minimal effect on the behavior of quantum wavefunctions themselves. However, it can impact our understanding of the universe as a whole, as the expansion of space can influence the behavior of particles and their interactions.

5. What are some current research and developments in the study of the expanding universe and quantum wavefunctions?

Currently, scientists are trying to reconcile the expanding universe theory with other theories in physics, such as quantum mechanics and general relativity. They are also studying the behavior of quantum wavefunctions in different conditions, such as in the early stages of the universe or in extreme environments, to gain a better understanding of the expanding universe.

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