Evaporating Universe

[ihwip]

Hi all,

I posed a question to my wife the other day and it lead to this line of thinking.

The original question was: If the sun were to emit a photon that never strikes another atom would that qualify as destruction of matter and energy since the matter and energy of the photon will never be observed?

This leads us to the end of the universe. Eventually everything is going to collapse into black holes and then those black holes will start evaporting via Hawking radition. Eventually those black holes will send out enough photons that do not land in other black holes so that the entirety of existence will be radiated out of the universe, turning into a virtual photon soup.

Is this correct?

 

[MeteorWayne]

No

 

[xXTheOneRavenXx]

LMAO, what's up with everyone and single word answers, lol

 

[Mee_n_Mac]

Hi all,

I posed a question to my wife the other day and it lead to this line of thinking.

The original question was: If the sun were to emit a photon that never strikes another atom would that qualify as destruction of matter and energy since the matter and energy of the photon will never be observed?

This leads us to the end of the universe. Eventually everything is going to collapse into black holes and then those black holes will start evaporting via Hawking radition. Eventually those black holes will send out enough photons that do not land in other black holes so that the entirety of existence will be radiated out of the universe, turning into a virtual photon soup.

Is this correct?

Not everything will fall into a BH. The expansion of space may leave many galaxies isolated from each other. When all the stars eventually die, and all the heat has been radiated away (that can be) you may end up with a Universe that's nothing more that a lot of cold dark matter. Now perhaps atoms and their constituents eventually decay as well but I don't know this to be fact and even then you end up with some cold dark odd matter.

 

[origin]

Hi all,

The original question was: If the sun were to emit a photon that never strikes another atom would that qualify as destruction of matter and energy since the matter and energy of the photon will never be observed?


Is this correct?

No. To elaborate a bit, the photon is NOT destroyed so this is not the destruction of energy. Even if it just scoots around the universe for all of eternity. It sounds like this is going to deteriorate into a semantics argument kinda like the question, "If Helen Keller falls in the woods does she make any noise". Depends on your defition of sound - is it the pressure waves moving through the air or is sound the detection of the pressure waves.

The answer to both questions is, Helen does make a sound - who cares if it is heard or not, and a photon that is not absorbed is still energy.

 

[sacr3]

Hi all,

The original question was: If the sun were to emit a photon that never strikes another atom would that qualify as destruction of matter and energy since the matter and energy of the photon will never be observed?


Is this correct?

No. To elaborate a bit, the photon is NOT destroyed so this is not the destruction of energy. Even if it just scoots around the universe for all of eternity. It sounds like this is going to deteriorate into a semantics argument kinda like the question, "If Helen Keller falls in the woods does she make any noise". Depends on your defition of sound - is it the pressure waves moving through the air or is sound the detection of the pressure waves.

The answer to both questions is, Helen does make a sound - who cares if it is heard or not, and a photon that is not absorbed is still energy.

Well, the way I see it. If the Photon never interacts with anything, and is never observed.. then it doesn't matter if it exists or not.. is it a destruction of energy? Well, I suppose if its never used or observed.. it had no original purpose then it may have been a "waste" of energy.. which in turn can be "destruction" but then we're just playing with words..

So imo, naw, its not destruction of energy.. maybe to living creatures it is because we will NEVER beable to use that energy so it might as well be non existant..

k this can go on forever, I don't think its Destruction, though I can see it being a waste of energy.

 

[eburacum45]

The description in the original post is quite feasible, I think. A respectable portion of the photons emitted by most of the stars in the universe will not be absorbed by any matter; they will just keep travelling at the speed of light while the universe expands around them, Eventually, (if the rate of acceleration of expansion continues) each photon will be alone inside a Hubble volume in which it is the only (non-virtual) particle.

Of course the continued expansion of the universe is not necessarily guaranteed; but it is one option which can be considered as both possible and realistic.

 

[vogon13]

As these photons travel into space, and into the future, the expansion of the universe redshifts them and their energy decreases.

Eventually, they all are individually of ~0 energy, and alone in a volume of space ~infinitely bigger than the universe today.

Not so much erased, or unobserved, but diluted.

Infinitely diluted.


And then the expansion of the universe goes on for another 10^10^10^34 years.


Note:

The current size of our universe currently limits the lowest possible energy of a photon possible. Wavelengths increase as energy decreases, and wavelengths bigger than the universe are not possible. Therefore, the creation of those photons is inhibited. Essentially, the 'impedance' of the universe messes up the SWR of these low wattage photons.

As the universe expands, the lower limit of photon energy decreases, and whilst their numbers may increase, they remain undetectable since antennas the size of the universe are difficult to build.

 

[yevaud]

Exactly as Vogon says. Apply a very high temperature to a volume of 1 cubic meter, it will be very hot; apply the same very high temperature to a volume measured in cubic light years, well...diluted is accurate.

Also, you've heard the quote "energy can neither be created nor destroyed, only converted from one form to another." Well, that is succinctly so, in the sense that all of the energy the Universe possesses was there from the beginning. No "new" energy is ever created (that would be a form of perpetual motion, so to speak, and violate conservation of energy, to have energy or matter "appear" from nowhere). So it really matters not if a Photon ever interacts with anything, ever. It is still a part of the total energy bound up in the universe.

 

[derekmcd]

Whether you realize it or not, you are still affected by photons from across the universe. This is explained by Inflationary comology and how it resolves the horizon problem. The size of the universe is larger than a photon could travel. However, during a very early epoch of the universe, Inflation took place to explain how causality exists between these parts of the universe and why it is homogeneous and isotropic.

The photon you never see also contributes to the stress-energy tensor as defined by General Relativity. Whether you personally, physically realize the existence of the photon, it still contributes to the overall mass of the universe. You are affected by it even if you don't see it.