if light went in a circle

[lemur]

I don't know if light could ever travel in a recursive loop without some gravitational mass to curve space. I've heard some people say that light can generate gravity in itself, so maybe there's some situation possible in which light could curve into a loop due to its own innate gravity. Either way, the point is that I would like to know whether IF light would travel in a closed loop, would the loop have inertia/mass or could it travel at C as a loop? It seems to me that it would not be possible for such a loop to move at C because as it approached C, one side of the loop would be redshifting while the other would be blueshifting. It seems like particles with mass could resist force for a reason related to this.

[lemur]

Should this thread be in speculations? I'm using this scenario as a way to think about the relations between light, motion, and force. I hope someone's physics permits them to contemplate it.

[ajb]

http://en.wikipedia.org/wiki/Photon_sphere

 

I am sure that such null geodesics are unstable, that is a small perturbation will send the photon crashing into the compact object or off to infinity.

[lemur]

http://en.wikipedia....i/Photon_sphere

 

I am sure that such null geodesics are unstable, that is a small perturbation will send the photon crashing into the compact object or off to infinity.

Thanks for the link as well as for the term, "null geodesic." I was actually thinking that maybe the quantum nature of the waves could be a stabilizing factor in such a loop. I.e. if the alternating electric and magnetic fields would somehow become integrated (perhaps by attraction between the magnetic fields of the wave), then maybe they would naturally continue propagating into themselves and even resist destabilization according to the strength of their "head-tail bond."

 

This is getting too speculative, probably, but the part I was really interested in is if such a configuration would be stabile, could it have inertia as a result of, say, resistance between the two sides of the loop to interfering with each other. Or if the thing was moving, would one side redshift and the other side blueshift, with some polarizing effects between the two sides. I'm assuming here that energy can/could transfer through the length of the EM wave as compression (blueshift) of one part would require decompression (redshift) of the other due to conservation of energy.

In the case that it could, I would expect linear motion to cause the redshift/blueshift differential that would in turn create an energy-disequilibrium in the wave, which could make it behave like a particle with charged poles, maybe?

Edited March 3, 2011 by lemur

[DrRocket]

I don't know if light could ever travel in a recursive loop without some gravitational mass to curve space. I've heard some people say that light can generate gravity in itself, so maybe there's some situation possible in which light could curve into a loop due to its own innate gravity. Either way, the point is that I would like to know whether IF light would travel in a closed loop, would the loop have inertia/mass or could it travel at C as a loop? It seems to me that it would not be possible for such a loop to move at C because as it approached C, one side of the loop would be redshifting while the other would be blueshifting. It seems like particles with mass could resist force for a reason related to this.

 

I don't think the answer is settled, but something similar was hypothesized by Wheelere, the geon.

 

http://en.wikipedia.org/wiki/Geon_(physics)

[lemur]

I don't think the answer is settled, but something similar was hypothesized by Wheelere, the geon.

 

http://en.wikipedia....i/Geon_(physics)

There's no page. Is there some other name to search under?

[imatfaal]

There's no page. Is there some other name to search under?

 

http://en.wikipedia.org/wiki/Geon_(physics)

 

the closing bracket was missing from link

[lemur]

http://en.wikipedia..../Geon_(physics)

 

the closing bracket was missing from link

Thanks. This appears to be exactly what I am thinking of. The wiki article says that the energy would probably "leak away" even if the thing was stable enough to remain intact. I wonder what basis there is for thinking an EM wave can "leak?" Do/can photons fragment? How can they considering that their energy is quantized? If such a loop could form, I would think it would feed on itself insofar as photon-propagation seems to be related to complimentarily and exclusion between electric and magnet fields. It's like the one field draws on the other to propagate itself to its next replicant. Put another way, it's like the electric field generates a magnetic field, which in turn generates a new electric field, which "pulls" the energy of the first electric field forward because of conservation of energy. Anyway, I don't know if I'm assuming too much from relatively intuitive understandings of these waves and their fields but I don't see why energy would just randomly "leak" out of a closed system. Maybe it would help if I had some more knowledge of quantum gravity theories.

[ydoaPs]

http://en.wikipedia.org/wiki/Photon_sphere

 

I am sure that such null geodesics are unstable, that is a small perturbation will send the photon crashing into the compact object or off to infinity.

Even assuming stability, I'm not sure how one would think that the light itself would have mass. Any gravitational field strong enough to make light orbit would needless to say have a tremendous amount of mass. Since the light would have to stay with the enormously massive object in order to orbit it, the loop of light(treating the loop as an object instead of analyzing the individual photons) would have a sublight speed, but that's not due to the light itself.

[lemur]

Even assuming stability, I'm not sure how one would think that the light itself would have mass. Any gravitational field strong enough to make light orbit would needless to say have a tremendous amount of mass. Since the light would have to stay with the enormously massive object in order to orbit it, the loop of light(treating the loop as an object instead of analyzing the individual photons) would have a sublight speed, but that's not due to the light itself.

Suppose Hawking radiation generates photons near the perimeter of a black hole. Then, suppose some of those photons occur at a level of gravitation that causes them to radiate outward but gravity-fluctuations subsequently cause the photon to be pulled backward toward the BH again. Maybe at that moment, it could get "bound up with its own tail" electromagnetically and then get carried away from the black hole by gravity waves. It probably sounds far-sought but I don't see what's so implausible about a black hole whose gravity fluctuates/oscillates - although the photon propagating into its own tail end and getting stuck in a loop is a bit more speculative, I think. Still, is there any physical law or reason that would exclude the possibility of an EM wave propagating intensively instead of extensively?

 

 

[ydoaPs]

I suppose if you have two strategically placed beams going in opposite directions, they could attract each other and end up chasing each other. Being so close, though, I'm not sure if there'd be any quantum effects.

[lemur]

I suppose if you have two strategically placed beams going in opposite directions, they could attract each other and end up chasing each other. Being so close, though, I'm not sure if there'd be any quantum effects.

 

I wondered if such a loop would exhibit inertial characteristics. E.g. if the loop was pushed (accelerated), it could contract in length as it wouldn't be perfectly inelastic. In that case, could the two sides of the loop resist contact because they are going in opposite directions, for example? Also, could the direction of motion produce an energy-concentration asymmetry by redshifting the side going in the opposite direction of motion and blueshifting the side going in the same direction? If so, I wonder if such an asymmetry could result in a form of polarity.