The attraction of massless particles to other massless particles and to matter

May 2019
2
1
I am really hoping someone might be able to offer a solution or at least offer guidance on something that is interesting me - are massless particles more attracted to particles with mass or other massless particles.

A good example to work with could be photons: is light more attracted to matter or to other photons...

High-power laser beams can bend other laser beams, which means that streams of light do affect each others trajectory; streams of light attract other streams of light (proved by the harvard biophotonics group, I believe)

&

In 1919, four years after Einstein fully formulated his theory of gravity, his General Theory of Relativity, it was proven that light could indeed find itself attracted to objects with mass by measuring how much a beam of light could bend in their vicinity.

I would really love to know which provides most attraction. And if so, I’d love to know why.

I’ll look forward to anyone who might be able to shed a little, eh, light.

Best wishes
James
 
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topsquark

Forum Staff
Apr 2008
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On the dance floor, baby!
I’ll look forward to anyone who might be able to shed a little, eh, light.
(Groans)

According to GR any two particles that carry energy (which means all of them) are attracted to each other via the gravitational force. But when dealing with subatomic particles the effect is very very small.

Aside from that we need to look at other interactions. For example, in QED (the quantum version of electromagnetism) there is no direct mechanism for a photon to scatter off another photon because photons do not carry electric charge. The photon can mediate the interaction between two other charged particles but not with itself. (Actually there is a Feynman diagram that will do this, but it's a very small correction.)

And that's it. Photons are one of the mediators of the electroweak force but again the correction is very small. (In fact it's the same Feynman diagram as above.) And photons don't participate in the strong force at all.

As to other massless particles we have a similar shopping list. The are neutrinos, gluons, and gravitons (as yet to be discovered). They all participate in their own interactions with massive particles but they all have to be looked at one interaction at a time.

-Dan
 
Apr 2015
1,238
359
Somerset, England
Hello, James.

Which of the four fundamental forces in the 'Standard Model' are you thinking of?

Massless charged particles have never been observed in particle ciolliders, although they have been sought.
So that rather seems to rule out photons as they are the exchange mediators for the electromagnetic force.
As to other photon effects, don't forget that photons have momentum and energy, although they have no mass.
And energy is one of the terms in the GR tensor which warps spacetime.

Have you any proper references for your claims about photons?
 
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Apr 2017
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A quick google search ....."Does light have mass "

Answer ...."Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass, and this is confirmed by experiment to within strict limits."

So then why does gravity bend light ????......

"Light can form a curve if it travels near a big mass. You are right, photons don't have mass. You are also right, photons doesn't follow Newton's gravitation law. Photons can be pulled by gravity not because of their mass (they have none) but because gravity bends space-time...."

"Because gravity bends space and time !" ...Am I the only one to think something is not right here????

The first answer says light has proven to have no mass "confirmed by experiment" ...but it has momentum!!! well the best experiment I can think of is to shine light past a large mass (star) !!!
 
Last edited:
Oct 2017
676
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Glasgow
"Light can form a curve if it travels near a big mass. You are right, photons don't have mass. You are also right, photons doesn't follow Newton's gravitation law. Photons can be pulled by gravity not because of their mass (they have none) but because gravity bends space-time...."

"Because gravity bends space and time !" ...Am I the only one to think something is not right here????
Lot's of people don't think this sits right with them either. Einstein's GR has however been proven to be true every time, so it's look like we just have to get used to the idea that it's effects are real and you have things like photons being affected by gravity.

If you look at gravitational lenses, you get some really funky things happening. :)
 
Mar 2019
935
50
cosmos
massless vs meaningless

Such terms as "massless particle", "hypethetic particle", etc, are rendering monder physic to become more and more cryptic and illusory, even on the brink of losing physical meaning...
The 2018 Nobel Price project "light trap" is a direct proof of photon has mass. The density of photon is higher in the center of the laser beam, so the mass density is higher too. That draws the molecule to the center of the laser beam.
If the laser beams can bent the trajetory of each other, it will be another proof.
 
Apr 2017
542
140
Lot's of people don't think this sits right with them either. Einstein's GR has however been proven to be true every time, so it's look like we just have to get used to the idea.... :)
I think that position is true for many physicists .... They don't quiet get it themselves , but assume the problem is with their understanding .... How could Einstein be wrong??? how could all mainstream physics be wrong???

I suggest to you this is all part of the conspiracy... There is science for the masses .. and true advanced science which is kept off world away from the surface population . Off world they have antigrav , faster than light travel , wormholes , time travel and much more (according to 100's insiders)...

Fake science is maintained here by the cabals control of Universities and institutions ... they make sure only the believers hold professorships and other positions....

And what is the experimental evidence that holds up relativity ? (Not all of GR is wrong) ...

Well gravity bending light is experimental evidence .... and the obvious conclusion that light must have mass is denied by using an analogy a thought experiment of bending of 'space time' .... people understand the analogy and so think they understand reality!
 
Apr 2015
1,238
359
Somerset, England
Off world they have antigrav , faster than light travel , wormholes , time travel and much more (according to 100's insiders)...
You missed out wombles.

Please, this is a Physics site, not a bed time story site.
 
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Jun 2016
1,370
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I must admit I am confused.

Energy = Mass * c^2

I think that I have read that at CERN they observe high energy photons becoming particles and visa versa.

Photons are not affected by the Higgs field, so don't have mass?

However via E=mc^2 the light energy of a galaxy equivalences to a not insignificant mass.
Does this contribute to the spacetime warping of its gravity?
 
Apr 2015
1,238
359
Somerset, England
I must admit I am confused.

Energy = Mass * c^2

1) I think that I have read that at CERN they observe high energy photons becoming particles and visa versa.

2) Photons are not affected by the Higgs field, so don't have mass?

However via E=mc^2 the light energy of a galaxy equivalences to a not insignificant mass.
Does this contribute to the spacetime warping of its gravity?
1)

Sometimes particles eg an electron/positron pair can meet and result in total anihilation in a burst of EM radiation, which meets conservation reuqirements.

The reverse process has also been observed, that is sponataneous creation of particles from radiation. Note this is not creation of matter from nothing - it still obeys conservation laws.

2) Yes but remember you can't just add these things up. Mass and energy are both represented in the stress-energy tensor in GR and contribute to the curvature tensor which results.
To obtain the contributions, you have to follow the rules of tensor algebra.
 
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