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The Gravity of a Photon

jwkennington.com

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Re: The Gravity of a Photon

#21

Post by Xcelerate »

danbruc wrote: post #15
Xcelerate wrote: post #12

I find gravity interesting, because everything that exists interacts with everything via the gravitational field. This is not the case with any other sort of interaction; gravity is truly different. See this diagram showing the ways that different particles can interact in the Standard Model: https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/El... Photons, for instance, cannot interact directly with each othe…

Photons do interact electromagnetically [1], just not in the same direct way as gluons. [1] https://en.wikipedia.org/wiki/Two-photon_physics

Yeah, I was more so speaking of direct coupling but didn’t want to get too technical. That interaction is due to virtual fermion-antifermion pairs.

Re: The Gravity of a Photon

#22

Post by tsimionescu »

danbruc wrote: post #18
dschuetz wrote: post #16

Earlier quoted context omitted.

"there is gravity in the absence of EM fields" That just cannot be true. EM fields are just about everywhere. They permeate space almost as universally as gravity, but in form of photons (to name higher energy EM fields here) or other low energy waves. Gravity accumulates with great masses, mass is also energy (in rest). The article explores the idea that pure kinetic energy in form of photons indeed might have at le…

EM fields are just about everywhere. Fields are mathematical tools, they are not - without wanting to go down the philosophical rabbit hole - real things out there in the universe. And the thing about everything just being electromagnetic fields is nonsense, physicists understand physics way better than you do. Sorry to sound condescending, but the internet already has enough obviously wrong ideas by random people wi…

Honest question: aren't radio waves "physical objects" that represent oscillations of an electro-magnetic field, to the best of our current understanding?

Re: The Gravity of a Photon

#23

Post by kgwgk »

dschuetz wrote: post #16
kgwgk wrote: post #13

Earlier quoted context omitted.

What would that mean? As far as we know there is gravity in the absence of EM fields and EM energy produce gravitational effects just like other forms of energy (and in the realm of direct human experience the contribution of EM is negligible).

"there is gravity in the absence of EM fields" That just cannot be true. EM fields are just about everywhere. They permeate space almost as universally as gravity, but in form of photons (to name higher energy EM fields here) or other low energy waves. Gravity accumulates with great masses, mass is also energy (in rest). The article explores the idea that pure kinetic energy in form of photons indeed might have at le…

> The article explores the idea that pure kinetic energy in form of photons indeed might have at least gravity-like properties.

Saying “explore”, “idea”, “might” makes it sound as if this was not a well-established 100-years-old theory.

> My presumption is that atoms are somehow made of really high energy EM fields so that they appear to be massive.

Somehow... The easiest way to proceed in that program of research may be to rename the standard model as ElectroMagnetism and try to get a unified theory of the strong, weak and the-force-previously-known-as-em forces. Then you unify that with GR and you’re done :-)

Re: The Gravity of a Photon

#24

Post by zaarn »

dschuetz wrote: post #16
kgwgk wrote: post #13

Earlier quoted context omitted.

What would that mean? As far as we know there is gravity in the absence of EM fields and EM energy produce gravitational effects just like other forms of energy (and in the realm of direct human experience the contribution of EM is negligible).

"there is gravity in the absence of EM fields" That just cannot be true. EM fields are just about everywhere. They permeate space almost as universally as gravity, but in form of photons (to name higher energy EM fields here) or other low energy waves. Gravity accumulates with great masses, mass is also energy (in rest). The article explores the idea that pure kinetic energy in form of photons indeed might have at le…

Easy way to check, just wave a long piece of iron through the air. If there is truly a massive EM field, it should induce a decent voltage into said iron rod as it moves through the magnetic field lines produced by the "gravity EMism"

Considering noone died from waving iron rods through the air by way of electrocution (other than lightning) I'd say that means gravity is not an EM field.

There is also a different test: EM fields are either positive or negative in charge. If you have three objects, in an EM field they cannot all three attract eachother, one object must be pushed away from one of the other two.

Considering we don't see that behaviour in our solar system, gravity cannot be an EM field.

Re: The Gravity of a Photon

#25

Post by dschuetz »

tsimionescu wrote: post #19
dschuetz wrote: post #16

Earlier quoted context omitted.

"there is gravity in the absence of EM fields" That just cannot be true. EM fields are just about everywhere. They permeate space almost as universally as gravity, but in form of photons (to name higher energy EM fields here) or other low energy waves. Gravity accumulates with great masses, mass is also energy (in rest). The article explores the idea that pure kinetic energy in form of photons indeed might have at le…

> EM fields are just about everywhere. They permeate space almost as universally as gravity Isn't dark matter most likely some kind of material that has mass, but no EM interaction? We also know that there are interactions inside atoms (the strong and weak forces) that have no known relation to electro-magnetism, so I'm not sure what you are getting at.

As far as I understand, dark matter is an educated guess (which was made upon the discovery that galaxies rotate differently than expected). Something out there must be causing gravity, but we cannot see it, which means that there is no observable EM interaction.

The next guess here is that dark energy has a much much higher rest energy so that no photon in this universe is able to interact with it via EM fields. The search for dark matter was unsuccessful so far, and the LHC is still trying to achieve higher energies to be able to detect dark matter. So, dark matter is just a guess.

The interactions inside atoms seem to have no known relations to EM, because, and this is my guess, there are much higher energies at work than we know. So, if dark matter is hiding behind high energies so that EM interaction seems impossible, why should it be different for EM interactions inside atoms. There still is a slim chance that it might be EM, just at much higher energies.

Re: The Gravity of a Photon

#26

Post by dschuetz »

tsimionescu wrote: post #22
danbruc wrote: post #18

Earlier quoted context omitted.

EM fields are just about everywhere. Fields are mathematical tools, they are not - without wanting to go down the philosophical rabbit hole - real things out there in the universe. And the thing about everything just being electromagnetic fields is nonsense, physicists understand physics way better than you do. Sorry to sound condescending, but the internet already has enough obviously wrong ideas by random people wi…

Honest question: aren't radio waves "physical objects" that represent oscillations of an electro-magnetic field, to the best of our current understanding?

There is an agreement in physics that low energy EM fields are called waves, such as radio waves, and high energy EM fields are called photons or even particles. In any case they are actually both. If they are physical objects I don't know. I think, I wouldn't go that far.

Re: The Gravity of a Photon

#27

Post by danbruc »

tsimionescu wrote: post #22
danbruc wrote: post #18

Earlier quoted context omitted.

EM fields are just about everywhere. Fields are mathematical tools, they are not - without wanting to go down the philosophical rabbit hole - real things out there in the universe. And the thing about everything just being electromagnetic fields is nonsense, physicists understand physics way better than you do. Sorry to sound condescending, but the internet already has enough obviously wrong ideas by random people wi…

Honest question: aren't radio waves "physical objects" that represent oscillations of an electro-magnetic field, to the best of our current understanding?

Radio waves are streams of photons, the fields are just a mathematical tool we use to describe this. And there are several of them, the classical electromagnetic field but also an entire set of fields involved in the quantum version.

Re: The Gravity of a Photon

#28

Post by kgwgk »

danbruc wrote: post #27
tsimionescu wrote: post #22

Earlier quoted context omitted.

Honest question: aren't radio waves "physical objects" that represent oscillations of an electro-magnetic field, to the best of our current understanding?

Radio waves are streams of photons, the fields are just a mathematical tool we use to describe this. And there are several of them, the classical electromagnetic field but also an entire set of fields involved in the quantum version.

Other people may say that photons are just mathematical tools that we use to describe fields. :-)

Re: The Gravity of a Photon

#29

Post by thomaswang »

jessriedel wrote: post #5
xupybd wrote: post #4

Wow I didn't expect that! For the layperson that's really interesting. "the conventional electromagnetic fields, and the photons that constitute them, impact the gravitational field despite having no inertial mass!" Does that mean the build up of the photon sphere around a black hole would have a significant impact on space time?

The photon sphere is not a place where photons collect because the orbits along the sphere are unstable fixed points. Small perturbations from these orbits either fall into the black hole or escape to infinity.

Is there a line between where light neither escape or get swallowed. Simply just stands still in perfect balance between being pulled and escaping?

Re: The Gravity of a Photon

#30

Post by dschuetz »

danbruc wrote: post #27
tsimionescu wrote: post #22

Earlier quoted context omitted.

Honest question: aren't radio waves "physical objects" that represent oscillations of an electro-magnetic field, to the best of our current understanding?

Radio waves are streams of photons, the fields are just a mathematical tool we use to describe this. And there are several of them, the classical electromagnetic field but also an entire set of fields involved in the quantum version.

Oh yes, quantum electromagnetic quantum field. Just add "quantum" and the discussion is over.
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