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Quote from: Foolosophy on 07/01/2011 05:48:17And of course if the photon did indeed turn out to be NON-massless, then the speed of light cannot be a constant and even the innate beauty of the expression E=mc^2 will have to be re-written in another way. If the photon is found to be non-massless, we'll need to just change our terminology so that c is the "cosmic speed limit," then E=mc^{2} still holds, whereas light now acts like other massive particles and can never reach that speed. However, there is no evidence whatsoever that light has mass.

And of course if the photon did indeed turn out to be NON-massless, then the speed of light cannot be a constant and even the innate beauty of the expression E=mc^2 will have to be re-written in another way.

In special relativity a critical assumption is that there exists a cosmic speed limit. Since light is massless, this is equal to the speed of light. If you wanted to make up a universe where light had mass, you'd still have a cosmic speed limit and light would be like anything else zipping around within it.If a photon is non-massless, therefore, you could calculate its energy just like you calculate the energy of any moving particle with mass. E^{2}=m^{2}c^{4}+p^{2}c^{2}.

Yor_on, why must you stick your head into the box?Try to answer this:A policeman is measuring, with the police radar thing, the speed of a cow that is walking away from the police. Radar wave gets redshifted. Where does the energy go?

JP I think Foolsophy have a valid point there, it's not only to change one expression. You will need to go over all expressions that build on the assumption of bosons for that then, not that I know all there is And also all further expressions that build on those assumptions ad infinitum.

If it was as simple, and if it mattered that little to our universe then I would expected Einstein to already have considered it when creating his theory of relativity.

I doubt he missed the inherent 'mysticism' in having bosons and 'point particles' interacting without 'existing' in SpaceTime. So if he never even considered giving light an invariant mass I'm sure he had good reasons.

Photons we have experimental evidence for, gluons? I don't know any experimental proofs myself, isn't they theoretical 'particles' still?

Are you stating that Einstein didn't 'know' that his theory would hold if he allowed for a slight invariant mass? Maybe, I'm not sure there, he seems to have looked after the simplest explanations that made sense to him, and us too possibly I would have expected him to want them to have a certain invariant mass, if he thought he could get away with it as they still are mysterious things, no matter that we know them to interact.That's a really nice question btw, why didn't he allow for a slight invariant mass if it now would make no difference? To me that would make a world of difference, as Jaztra's ideas for example, mass/energy?

An escaping mirror and a motionless mirror receive various energies from photons.An escaping mirror takes more energy.

Quote from: QuantumClue on 06/01/2011 14:04:55I'll be honest, I'm not sure what it means. The OP says:''The experts say that when mass m is lowered into a black hole, that has mass M, then this is the energy of the mass m down at the event horizon''so the quantity here 1/4Mc^2 is referring to a particle with a mass yes? Or does the energy relate to the black hole? If its the particle, nothing spectacular has happened to the energy I would assume. Energies which are lowered or increased for a system with a mass usually have to do with the kinetic energy... so it's lost kinetic energy...I could be wrong.Black Holes are quite different creaturesThey apparently seem to violate some fundamental laws of physicsthe 1/4mc^2 term relates to the rest mass ENERGY.The body of mass "m" accelerates towards the speed of light as it enters the black hole event horizonIs the mass converting to "non-kinematic" energy?Are you saying that the black hole absorbs 75% of the rest mass ENERGY and 25% is lost?What is this efficiency term you talk about?How does it relate to the Hawking radiation of balck holes?

I'll be honest, I'm not sure what it means. The OP says:''The experts say that when mass m is lowered into a black hole, that has mass M, then this is the energy of the mass m down at the event horizon''so the quantity here 1/4Mc^2 is referring to a particle with a mass yes? Or does the energy relate to the black hole? If its the particle, nothing spectacular has happened to the energy I would assume. Energies which are lowered or increased for a system with a mass usually have to do with the kinetic energy... so it's lost kinetic energy...I could be wrong.

Quote from: Foolosophy on 06/01/2011 14:17:19Quote from: QuantumClue on 06/01/2011 14:04:55I'll be honest, I'm not sure what it means. The OP says:''The experts say that when mass m is lowered into a black hole, that has mass M, then this is the energy of the mass m down at the event horizon''so the quantity here 1/4Mc^2 is referring to a particle with a mass yes? Or does the energy relate to the black hole? If its the particle, nothing spectacular has happened to the energy I would assume. Energies which are lowered or increased for a system with a mass usually have to do with the kinetic energy... so it's lost kinetic energy...I could be wrong.Black Holes are quite different creaturesThey apparently seem to violate some fundamental laws of physicsthe 1/4mc^2 term relates to the rest mass ENERGY.The body of mass "m" accelerates towards the speed of light as it enters the black hole event horizonIs the mass converting to "non-kinematic" energy?Are you saying that the black hole absorbs 75% of the rest mass ENERGY and 25% is lost?What is this efficiency term you talk about?How does it relate to the Hawking radiation of balck holes?Don't let the subject line confuse you.Sun has 0.7% efficiency.An efficient real quasar has 20 % efficiency.An ideal quasar has 75% efficiency.A photon rocket has 50% efficiency at velocity 0.5 cA diesel engine has 40% efficiency, but not really, it's more like 0.000001%An engine where photon gas expands in a cylinder has ideally 100% efficiency.

Next frame.Same room, but our rocket is now accelerating non-uniformly, changing acceleration constantly. Will the light still behave the same as on Earth? Inside that room. Assume the room to be 10 light seconds. Put the light bulb at its far end, and in the direction of the rockets motion with you sitting near the rear. And this one is tricky, I expect people to have different opinions here, I have them too But I lean towards one though.

Now, let's go back to the first room. Let the room be 10 light seconds long. light-bulb at the front, you at the rear. Will the light be blue shifted reaching you?

The last room. Make it constantly uniformly moving, that is being in a 'free fall' with you being weightless inside it. Make it 10 light seconds long, light-bulb in front, you in the rear. Will the light 'blue/red shift' reaching you?

Now, is that true?Yep.In both my first examples I expended energy to make this acceleration.In the last example I might, or might not have expended energy, but it's indeterminable from inside that room. So let us look at light falling in to a Black Hole again. Where does that light 'expend energy'? Nowhere as i see it.Does the Black Holes gravity expend 'energy'?=='Indeterminable inside that room' as I'm not doing it (expending any energy) as we measure. And that's also what I mean by us looking at what really happens, not considering the 'what ifs'.

Now, is that true?Yep.In both my first examples I expended energy to make this acceleration.In the last example I might, or might not have expended energy, but it's indeterminable from inside that room. So let us look at light falling in to a Black Hole again. Where does that light 'expend energy'? Nowhere as i see it.Does the Black Holes gravity expend 'energy'?