Photons & Cosmic Expansion

[QuantumT]

According to researchers, the universe has produced 4x10⁸⁴* photons since the big bang, with a surprisingly dim effect.

So my question is: What has happened to all that energy?

I have previously suggested that photons could be involved in the cosmic acceleration, which was rejected.
But we know that photons can act as propulsion in solar sails, so why can't they act in the expansion of the universe itself?

 

* That's
4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 photons!

[StringJunky]

They are either moving through space or interacting with something.

[Strange]

5 minutes ago, QuantumT said:

But we know that photons can act as propulsion in solar sails, so why can't they act in the expansion of the universe itself?

Well, for one thing, the density of photons and therefore their effective pressure has decreased as the universe has expanded.

And their energy has decreased because of expansion (cosmological red-shift).

I'm sue there are other reasons ...

[swansont]

23 minutes ago, QuantumT said:

According to researchers, the universe has produced 4x10⁸⁴* photons since the big bang, with a surprisingly dim effect.

So my question is: What has happened to all that energy?

 

The volume of the observable universe is 4×10⁸⁰ m³ so that means 10,000 photons per cubic meter, on average

That would include radio waves, microwaves, IR, visible, UV, etc.

That gives us a flux of 3 x 10¹² photons  m^-2sec^-1

If we assume an average energy of 1 eV, then we have  3 x 10¹² eV m^-2sec^-1

That's what we would get from a 5 microWatt monochromatic source, if we were about a meter away. That's not very much energy. And space is big, so as StringJunky said, many of them are still out there, moving around.

[MigL]

As Strange mentioned the density of radiation has decreased as the universe has expanded.
Yet expansion is accelerating...

Your 'cause' doesn't seem to fit the effect.

[QuantumT]

23 minutes ago, swansont said:

If we assume an average energy of 1 eV

13 minutes ago, MigL said:

Your 'cause' doesn't seem to fit the effect.

If we added quantum fluctuation to it, like I suggested in my old thread, would that have no effect?

For arguments sake, let's say a 1 eV charged photon hit a QF particle (not the anti-matter one), what would happen?

[MigL]

You have no idea what would happen yet you make conjectures ?

You realize that theory says elementary particles are surrounded by a 'halo' of virtual particles ?
So why would a quantum fluctuation giving rise to virtual particles have any 'other-than-normal' effect ?

[QuantumT]

1 minute ago, MigL said:

You have no idea what would happen yet you make conjectures ?

No, I ask questions. I thought I was allowed to do that. I want to learn more about particle physics.

[Strange]

16 minutes ago, QuantumT said:

If we added quantum fluctuation to it, like I suggested in my old thread, would that have no effect?

Why? It can't generate any more energy.

[QuantumT]

All right then. Thank you all for answering my questions.

[Mordred]

We account for radiation pressure due to photons in the FLRW equations, as mentioned its density falls off as a function of volume. The ratio its density reduces follows the relation to the scale factor of [latex]\rho\propto a^{-4}[/latex]. In the early universe the radiation pressure was sufficient to be the dominant contributor to expansion (this includes all particles whose momentum greatly exceeds its rest mass) such as neutrinos however as the volume increases they simply dilute to the point where they can no longer counter the gravitational terms. The next stage is matter dominant which is harder to explain how it can contribute to expansion but a simple explanation is that as matter starts to form structures its average density decreases so gravity has less of a hold in the regions away from the structure formations. The stage were at now is the Lambda dominant (DE or cosmological constant). 

see here for more details

https://en.wikipedia.org/wiki/Equation_of_state_(cosmology)

Edited February 21, 2019 by Mordred

[QuantumT]

A thing that has made me wonder is, how a photon can go from zero to C in an instant?

That is partly why I made this thread. It seems like a lot of power!

I realise that photons are radiation, and as such does not require locality like matter would. Is that the answer?

[StringJunky]

25 minutes ago, QuantumT said:

A thing that has made me wonder is, how a photon can go from zero to C in an instant?

That is partly why I made this thread. It seems like a lot of power!

I realise that photons are radiation, and as such does not require locality like matter would. Is that the answer?

Yes, it is strange thing at first but not once you realise that there is no rest state for a photon, so they are never at zero. The instant they exist they are travelling at c. It's important to note that they don''t exist at zero because they have become part of the absorbing electron. To clarify: they don't accelerate at all.

Edited February 21, 2019 by StringJunky

[swansont]

16 hours ago, QuantumT said:

If we added quantum fluctuation to it, like I suggested in my old thread, would that have no effect?

For arguments sake, let's say a 1 eV charged photon hit a QF particle (not the anti-matter one), what would happen?

There is no such thing as a charged photon.

I don't know how likely it is for a photon to interact with a virtual particle. It is possible to "promote" a virtual particle pair into being real by adding energy, so there is a chance you could do this with a photon, provided the fluctuation had an energy deficit smaller than the energy of the photon.

 

[QuantumT]

On 2/22/2019 at 12:49 PM, swansont said:

There is no such thing as a charged photon.

I thought you meant that each photon was ~1 eV. Volt is a charge, but it sounded strange to me too 

On 2/22/2019 at 12:49 PM, swansont said:

I don't know how likely it is for a photon to interact with a virtual particle. It is possible to "promote" a virtual particle pair into being real by adding energy, so there is a chance you could do this with a photon, provided the fluctuation had an energy deficit smaller than the energy of the photon.

That is very exciting reading!

I have a graphic/visionary approach to physics. I see 3D films in my mind, how molecules, atoms and particles behave and interact under different circumstances.
I know that most (if not all) physicists use math, and I would love to learn to do that as well. Put some writing to the images. I consider that my biggest challenge.

If I state, that you can see stars, no matter where you are in the universe, would that be wrong?
And if that is correct, then most (if not all) QF's would be hit by photons, or what?
We would then only need some of them to result in promotion, to turn the phenomenon into a heavy contributor to new matter. New matter that would add volume to space, and push its boundaries.

I know this a far fetched, and full of "if's", and I do not claim that it is real or even possible, but it is how I envision it.

[Sensei]

1 hour ago, QuantumT said:

I thought you meant that each photon was ~1 eV. Volt is a charge, but it sounded strange to me too 

eV, electron-Volt, is unit of energy. Volt is also not unit of charge. Charge is Q in Coulombs...

So, you basically have no knowledge about physics, regardless of your nickname..

 

To simplify it to you, if you fire a bunch of particles, electric neutral particles, electric +1e charged partices and electric -1e charged particles in region where you have external electric field (created by existence of polarized electrodes). These particles will have bended trajectories of their traces, accordingly to their charges.

 

That's how CERN, or other particle detector works.

Edited February 23, 2019 by Sensei

[QuantumT]

2 minutes ago, Sensei said:

eV, electron-Volt, is unit of energy. Volt is also not unit of charge. Charge is Q in Coulombs...

So, you basically have no knowledge about physics, regardless of your nickname..

That is quite a pessimistic assessment.
I currently have no mathematical knowledge about physics, but I understand many principles and mechanics of it.
I would call my knowledge optimistically incomplete, or poor at worst.

[Sensei]

On 2/22/2019 at 12:49 PM, swansont said:

I don't know how likely it is for a photon to interact with a virtual particle. It is possible to "promote" a virtual particle pair into being real by adding energy, so there is a chance you could do this with a photon, provided the fluctuation had an energy deficit smaller than the energy of the photon.

That's interesting thought for mind. Suppose so we have photon traveling in space and it meets virtual-pair, at the same time, other photon is meeting counter-anti-particle of the same virtual-pair. Photons loses energy in the presence of virtual-pair the same (or not) amount. And virtual-pair disappears later. While photons still exist and travel through the space, the more such interactions happens on their path through space and time, the lower and lower and lower energies they have..

Edited February 23, 2019 by Sensei

[QuantumT]

22 minutes ago, Sensei said:

So, you basically have no knowledge about physics, regardless of your nickname..

I forgot to clarify why I use that name.
I use it because I am fascinated by QM, and because I think the name sounds cool. Plain and simple.

[Sensei]

4 minutes ago, QuantumT said:

I forgot to clarify why I use that name. I use it because I am fascinated by QM,

I appreciate your fascination..

 

[Phi for All]

1 hour ago, QuantumT said:

I have a graphic/visionary approach to physics. I see 3D films in my mind, how molecules, atoms and particles behave and interact under different circumstances.
I know that most (if not all) physicists use math, and I would love to learn to do that as well. Put some writing to the images. I consider that my biggest challenge.

What you have is bits of knowledge untethered to a foundational science education. This makes it seem to you like you have some kind of special intuition, but it's really just custom-made guesswork that makes perfect sense only to you. Since you don't understand the underlying principles, you're free to leap from point to point, convinced you're on to something because it all seems to fit in your mind in a way that the mainstream explanations don't. 

It's good to ask questions, to find out what those who really understand it know, and look for the most trustworthy explanations. Where you're going to run into trouble is with the assertions based on unsupported guesswork. Ask if you don't know rather than guessing or making something up.

[QuantumT]

4 minutes ago, Phi for All said:

Ask if you don't know rather than guessing or making something up.

That's exactly what I'm trying to do. I realize that I'm quite ignorant in your eyes, and I'm okay with that. It's more or less true, compared to you.
But I have to tell you about my chain of thoughts, to explain why I would ask such questions that I do. Like why I think photons could contribute to expansion.
You can then reject it or correct it, if you are generous enough to spend your time and effort on it. That would make me grateful.

[Mordred]

Well your right in so far as photons do contribute to expansion, it is part of the current radiation density term. It simply isn't a major contributor in our current universe time slice. Every particle species contributes to a certain degree, albeit some species less than others. The dominant contributor however in our current time slice is [latex] \Lambda [/latex].

However as explained in previous threads the standard model of particles contribution will continuously reduce as the volume increases, while [latex] \Lambda[/latex] stays constant to the point where any deviational evidence isn't sufficient to show a variation due to volume change.

 Hence as the universe expands [latex] \Lambda [/latex] becomes more and more the driving contributor to expansion. Eventually reaching the point where it will be the only contributor where it can be determined.

Edited February 23, 2019 by Mordred

[swansont]

2 hours ago, QuantumT said:

I thought you meant that each photon was ~1 eV. Volt is a charge, but it sounded strange to me too 

eV is energy. A 1 eV photon would be in the near-infrared (1.24 microns)

2 hours ago, QuantumT said:

That is very exciting reading!

I have a graphic/visionary approach to physics. I see 3D films in my mind, how molecules, atoms and particles behave and interact under different circumstances.
I know that most (if not all) physicists use math, and I would love to learn to do that as well. Put some writing to the images. I consider that my biggest challenge.

If I state, that you can see stars, no matter where you are in the universe, would that be wrong?

Doesn’t work so well underground.

2 hours ago, QuantumT said:

And if that is correct, then most (if not all) QF's would be hit by photons, or what?
We would then only need some of them to result in promotion, to turn the phenomenon into a heavy contributor to new matter. New matter that would add volume to space, and push its boundaries.

I know this a far fetched, and full of "if's", and I do not claim that it is real or even possible, but it is how I envision it.

No new matter. It’s quite likely the photon would promote both the particle and antiparticle if this happened. Not doing so would violate a bunch of conservation laws. Meaning that’s not going to happen.

They are virtual pairs. Not two individual virtual particles.

[QuantumT]

53 minutes ago, Mordred said:

Well your right in so far as photons do contribute to expansion, it is part of the current radiation density term. It simply isn't a major contributor in our current universe time slice. Every particle species contributes to a certain degree, albeit some species less than others. The dominant contributor however in our current time slice is Λ .

However as explained in previous threads the standard model of particles contribution will continuously reduce as the volume increases, while Λ stays constant to the point where any deviational evidence isn't sufficient to show a variation due to volume change.

 Hence as the universe expands Λ becomes more and more the driving contributor to expansion. Eventually reaching the point where it will be the only contributor where it can be determined.

10 minutes ago, swansont said:

eV is energy. A 1 eV photon would be in the near-infrared (1.24 microns)

Doesn’t work so well underground.

No new matter. It’s quite likely the photon would promote both the particle and antiparticle if this happened. Not doing so would violate a bunch of conservation laws. Meaning that’s not going to happen.

They are virtual pairs. Not two individual virtual particles.

Thank you for your explanations!

I know it must be somewhat of an annoyance for you to read proposals from fools like me, and then have to explain the science. I imagine it happens quite frequently.
I never meant to be annoying. I just thought I had a unique idea. An that must also be annoying for you. That we think, you didn't already consider that!

Once again, thank you for taking the time to enlighten me!

Edited February 23, 2019 by QuantumT