[CrazyScientist (OP)]

EM waves which propagate in vacuum don't interact with each other -

Sound waves clearly do interact- especially at high intensities.
[/quote]

So do EM waves - especially at high intensities. I've pasted earlier the link to wikipedia...

[Bored chemist]

and it results in change of frequency for the reflected photon.

Only if the mirror is moving.

If you use an infinitely massive mirror, that problem goes away.

I already pointed this out.

In order to be perfectly reflective the walls have to be infinitely massive (this causes other problems).

[Bored chemist]

So do EM waves

So your earlier post was wrong.

EM waves which propagate in vacuum don't interact with each other -

Come back when you have finished arguing with yourself.

[Bored chemist]

You claimed that photons will always maintain the same frequency,

That's the opposite of what I said.

Overall, the sum of the energies will be conserved The wavelengths of the photons will be "scrambled" and will settle down to a black-body distribution.

[CrazyScientist (OP)]

and it results in change of frequency for the reflected photon.

Only if the mirror is moving.

If you use an infinitely massive mirror, that problem goes away.

I already pointed this out.

In order to be perfectly reflective the walls have to be infinitely massive (this causes other problems).

Yes but it was your statement nor mine. I was talking about the oryginal scenario

[CrazyScientist (OP)]

So do EM waves

So your earlier post was wrong.

EM waves which propagate in vacuum don't interact with each other -

Come back when you have finished arguing with yourself.

Yes and in my next post I corrected myself

[CrazyScientist (OP)]

https://en.wikipedia.org/wiki/Two-photon_physics
In fact 2 photons can theoretically  interact with each other without any intermediate medium - but it can happen only at extremely high energies of interacting photons (gamma frequencies) and in practice it doesn't produce a gravitational singularity. What is being observed, is the creation of a pair of a matter particle and a corresponding antiparticle, which then annihilate each other in a tiny fraction of a second...

But from your post I might conclude, that according to GR photons can if fact interact with each other gravitationally(). Is this true?

[Bored chemist]

But from your post I might conclude, that according to GR photons can if fact interact with each other gravitationally(). Is this true?

As far as I'm aware.
And the alternative would be weird for two reasons.
1
Imagine a big strong box with an atom bomb in it floating in a bigger box in deep space.
And imagine that there's a pendulum clock sitting on the bigger box.


It is ticking away because the bomb is so big that it produces a gravitational field (at the wall of the box) that is the same as the Earth's gravity.

When the bomb goes off, all the debris is caught by the inner box. But, in doing so, it gets very hot.
That heat means that (briefly) there will be lots of photons rattling round in the inner box.
Their mass corresponds to the mass which is annihilated by firing the bomb.
Either the clock on the outer box carries on keeping time, in which case the photons must have an gravitational attraction for the pendulum, or it doesn't keep time- in which case you have to explain how it "knows" what has happened inside the box.

2
The easier proof is simple.
We know that light going past a star is diverted from its path.
And we know that  light carries momentum.
So we know that the gravity of the star changes the momentum of the light.
But a change in momentum requires a force.
So we know that the start exerts a force on the light.

And by Newton's third  law we know that the light must exert an equal and opposite force on the star.
That's the gravitational attraction of the photon for the star.

So we know that the relativistic mass of a photon has a gravitational attraction.
And ew know that the photon is also subject to gravitational attraction.
So we know that two photons attract each other (in a tiny way) via gravity.

That effect is usually too small to consider but, if you keep putting photons into a "box", eventually you end up with enough mass to form a black hole.

Don't try this at home.

[CrazyScientist (OP)]

Woow! It's the longest post I saw you ever made. It seems, that at last you became actually engaged in a scientific discussion... I'm somehow proud of myself

But from your post I might conclude, that according to GR photons can if fact interact with each other gravitationally(). Is this true?

As far as I'm aware.
And the alternative would be weird for two reasons.
1
Imagine a big strong box with an atom bomb in it floating in a bigger box in deep space.
And imagine that there's a pendulum clock sitting on the bigger box.


It is ticking away because the bomb is so big that it produces a gravitational field (at the wall of the box) that is the same as the Earth's gravity.

When the bomb goes off, all the debris is caught by the inner box. But, in doing so, it gets very hot.
That heat means that (briefly) there will be lots of photons rattling round in the inner box.
Their mass corresponds to the mass which is annihilated by firing the bomb.
Either the clock on the outer box carries on keeping time, in which case the photons must have an gravitational attraction for the pendulum, or it doesn't keep time- in which case you have to explain how it "knows" what has happened inside the box.

Ok, I have no idea why do you describe a light bulb enclosed by a spherical mirror, as a ticking bomb, which is about to explode, implode and turn into a black hole... If causing such a cosmic-scale disaster would be so simple, we would be dead long time ago...

But let's focus on the main issue of your description - you keep treating photons as time-finite packets of energy, which are being created during the emission and which then keep growing in numbers in a limited volume of space and become "squeezed" in that space, until they reach some critical density and explode and/or implode and/or turn into a black hole. Such depiction of the scenario, can be then compared to air molecules, that keep inflating a baloon until it pops (since it probably won't turn into BH). This is a completely invalid depiction a continuous light emission.

Maybe this will help - let's describe the space inside the spherical mirror in terms of fiding a single photon at the same frequency as the light emitted continuously by the source.You make the first measurement and find that photon at a specific location - ok, so a photon is/was present in that location. Then you make a second measurement at the same location and you don't detect this photon anymore in that space - can you then say, that at the time of second measurement there is no photon at the given location?

No! You will ALWAYS find a photon at each possible location in physical space - but it can vibrate at some different frequencies, than the one, which is characteristic for the light emitted by the source inside sphere. Number of photons doesn't change in time - what changes, is the probability distribution for each one of those photons, so in a  given moment of time, you can detect that photon only at some specific frequencies. However probability of detecting a photon at some specific frequencies, doesn't determine the factual existence of that photon in space. There are many diiferent things, which we know exist, even if we can't always detect them everywhere around us

Besides it is proven experimentally, that "my" depiction of photons and the EM radiation (consistent mainly with QM), is the one, which is valid. As long, as you will think about this situation in terms of space without photons, that is being gradually "filled" by photons produced during emission by the source, you will get nowhere except a fantasy land, where you can create a BH by enclosing a light source with a reflective material. GR completely fails in this senario and there's no sense to blindly stick to a model, which doesn't work....

TBC

[Bored chemist]

I have no idea why do you describe a light bulb enclosed by a spherical mirror, as a ticking bomb, which is about to explode, implode and turn into a black hole... If causing such a cosmic-scale disaster would be so simple, we would be dead long time ago...

I didn't.

If you think I did, please post a  quote.

It's the longest post I saw y

You should probably look harder.

This is a completely invalid depiction a continuous light emission.

All the evidence shows that light is quantised; there is no continuous emission.

You make the first measurement and find that photon at a specific location -

The uncertainty principle means that a photon doesn't have a specific location- it has a range of probable locations.

Besides it is proven experimentally,

You need to demonstrate that.

[CrazyScientist (OP)]

2
The easier proof is simple.
We know that light going past a star is diverted from its path.
And we know that  light carries momentum.
So we know that the gravity of the star changes the momentum of the light.
But a change in momentum requires a force.
So we know that the start exerts a force on the light.

And by Newton's third  law we know that the light must exert an equal and opposite force on the star.
That's the gravitational attraction of the photon for the star.

So we know that the relativistic mass of a photon has a gravitational attraction.
And ew know that the photon is also subject to gravitational attraction.
So we know that two photons attract each other (in a tiny way) via gravity.

That effect is usually too small to consider but, if you keep putting photons into a "box", eventually you end up with enough mass to form a black hole.

If what you say is true, we should be able to detect even a weak gravitational interaction between 2 parallel laser beams, if we would use lasers with enough power.

Your chain of thoughts has a major flaw - you forgot to take into account the fact, that when a source of gravity interacts with some test object with a rest mass, this object will resist the force, which is being applied to it, because of inertia, that comes from the rest mass.

Sadly Newton laws of motion break down, when we try to apply some external force to a photon. Photons don't have a rest mass and no inertia - besides they can't resist acceleration, since they can't be accelerated anymore. If there's any way, in which photons can give a part of their own energy to the system in somekind of a gravitational interaction, then it is probably only through the transfer of momentum when those photons "collide" into the source object. What a nice coincidence, that we just spoke about the momentum transfer - this mechanism seems to fit perfectly into this subject...

There's also one more thing - athough we are in fact capable to turn light into rest mass, matter created in this proces will always disappear in the moment, when we stop to "shine" the light on that matter - and it is not just the issue of an insufficient energy input. No matter how strong light we would use, matter created through 2-photon interaction will annihilate itself microseconds after it's creaation. It appers, that for some reason it is physically impossible for us to create the inertia of a rest mass by using only the momentum of a photon as a source of energy. Don't ask me why it is so - that's something, what I need to research in the near future...

Don't try this at ho.me

Hold my beer Do you want to make a bet? I give $50 that my prediction is the valid one and we won't see anything as spectacular, as light undergoing explosion-->implosion-->collapse into a BH - not even remotely.

Although at this moment I don't have the right conditions, to conduct such experiment, but rest assured, that if I will ever conduct it, I will show you a recording of the result - even if it would turn out, that you we're right... But on the other hand, if your predictions are valid, you will probably observe the results just couple miliseconds after me - right when you'll start being sucked into a black hole made of light, together with the surrounding space...  It can be fun...

[Bored chemist]

If what you say is true, we should be able to detect even a weak gravitational interaction between 2 parallel laser beams, if we would use lasers with enough power.

Do you have any idea how small the effect would be?

besides they can't resist acceleration, since they can't be accelerated anymore.

Thanks for clarifying the problem; you do not understand what acceleration is.
Go and look it up.

[CrazyScientist (OP)]

You should probably look harder.

Nah, I have better things to do...

All the evidence shows that light is quantised; there is no continuous emission.

By "continuous" I ment "extended in time" - as in the difference to emission of a single pulse.

The uncertainty principle means that a photon doesn't have a specific location- it has a range of probable locations.

Yes, but when you make an actual measurement of it's location, you will end up with a definitive result: you will find a photon at the given location or you won't find it there - it's called "wavefunction collapse"

You need to demonstrate that.

Well, there are such things, like resonance cavities for photons - for example in lasers or in a microwave owens. What is being observed in those cavities, is that the "trapped" EM radiation forms a standing wave (if the size of cavity is proper for the wavelenght of EM wave).- EM waves behave in such case similarly to sound waves, what shows that my analogy of a buzzing speaker submerged in a sphere of water is in fact valid...

I will soon come back to this subject, as it requires more attention...

Do you have any idea how small the effect would be?

So what? Our technology allows us to make quite precise measurements. Besides, if your concept of time-finite photons is correct, then it should be possible, to trap photons at a specific wavelenghts in a resonance cavity and increase their density to the point, where gravitational interactions would be strong enough, to be measured...

Thanks for clarifying the problem; you do not understand what acceleration is.
Go and look it up.

Acceleration - In mechanics, acceleration is the rate of change of the velocity of an object with respect to time.

So, how this can be applied to gravitational interactions of photons? In what frame velocity of photons is changing in time?

[Bored chemist]

Yes, but when you make an actual measurement of it's location, you will end up with a definitive result

No.
That's the whole point.

So what? Our technology allows us to make quite precise measurements.

We are good, but not that good.
(and you run into the uncertainty principle again.)

Acceleration - In mechanics, acceleration is the rate of change of the velocity of an object with respect to time.

So, how this can be applied to gravitational interactions of photons? In what frame velocity of photons is changing in time?

OK, technically, it's the velocity that you do not understand.
Here's a hint, it is not the same as speed.

[Bored chemist]

Besides it is proven experimentally, that "my" depiction of photons and the EM radiation (consistent mainly with QM), is the one, which is valid.

No it is not.
And this is not evidence for it.

Well, there are such things, like resonance cavities for photons - for example in lasers or in a microwave owens. What is being observed in those cavities, is that the "trapped" EM radiation forms a standing wave (if the size of cavity is proper for the wavelenght of EM wave).- EM waves behave in such case similarly to sound waves, what shows that my analogy of a buzzing speaker submerged in a sphere of water is in fact valid...

I know about EM radiation and sound in cavities.
It has nothing to do with your claim, has it?

[CrazyScientist (OP)]

No it is not.
And this is not evidence for it.

Actually analogy between sound and EM waves is quite commonly used by physicists throughout the history of physics...

https://www.alamy.com/the-analogy-of-sound-and-light-was-lately-given-by-professor-barrett-of-the-royal-college-of-science-dublin-on-some-experiments-illustrating-the-analogy-of-light-and-sound-the-professor-commenced-by-referring-to-some-of-the-well-about-eight-minutes-to-travel-to-birmingham-a-little-over-one-hundred-miles-while-in-the-same-time-the-light-from-the-flash-would-have-traveled-to-the-sun-a-distance-of-over-ninety-millions-of-miles-but-though-they-so-differ-in-the-rate-of-progress-both-light-and-sound-show-many-phenomena-in-common-flame-was-used-as-a-detector-of-sound-this-delicate-acoustic-image334319414.html

I know about EM radiation and sound in cavities.
It has nothing to do with your claim, has it?

Well I would say, that my scenario is a perfect example of photons trapped in a spherical cavity

[Bored chemist]

Well I would say, that my scenario is a perfect example of photons trapped in a spherical cavity

But then you say that, even if the mirror is perfect, there's a loss of energy.

That's not whata "perfect mirror" means.

Actually analogy between sound and EM waves is quite commonly used by physicists throughout the history of physics...

Yes; Obviously. And we all know that.
But it is not used for doing simulations of blackholes, because it probably won't work.

[talanum1]

Photons are made of Riemann-half-sphere-half-antispheres, with momentum encoded into it by added points of space. An antisphere is a sphere made of left out points of space.

[Bored chemist]

Photons are made of Riemann-half-sphere-half-antispheres, with momentum encoded into it by added points of space. An antisphere is a sphere made of left out points of space.

Thank you  for your "contribution", Talanum.

helping.JPG (28.02 kB . 475x335 - viewed 4219 times)

[CrazyScientist (OP)]

Well I would say, that my scenario is a perfect example of photons trapped in a spherical cavity

But then you say that, even if the mirror is perfect, there's a loss of energy.

Sure - even if a surface is in 100% reflective, photons will loose energy due to momentum transfer. Just as you said, the mirror would need to have an absolute density of mass (made of BH?), to overcome this issue. However, there are other ways to trap EM radiation at a specific frequency within the cavity - e.g. microwaves inside the owen. For practical reasons, this mechanism can be used, to test my claims experimentally.

That's not whata "perfect mirror" means.

Actually analogy between sound and EM waves is quite commonly used by physicists throughout the history of physics...

Yes; Obviously. And we all know that.
But it is not used for doing simulations of blackholes, because it probably won't work.

It's you, who claim, that my scenario would lead to the creation of BH. I say, that the system will reach an energetic equilibrium at a specific frequency of resonance and from that moment energy level in the system will remain constant - just like we'd observe in the case of a constant emission of sound in a dense medium.