I was curious about this. The speed of light doesnt plug into the Lorentz equations, so that is one reason why it is stated that nothing can accelerate to or travel at the speed of light. Is that why light viewed at the edge of the observable universe is said to be 13 billion years old or to have taken 13 billion years to get to us because it isnt subject to time dilation? I know it is subject to gravitational...although not gravitation "time"...dilation as seen with redshift and blueshift. I guess my question is as stated in the topic subject with one addition. What are the properties of light that allows it to not be subject to relativity?
Well, there are two redshifts that ligh exhibits. That from a source that is moving away from us through space, and that from a source that is being carried away from us with space (called cosmological redshift). 1) Photons have no rest mass. 2) Why aren't photons "subject" to relativity? I'm not sure what you mean by this?
Photons are zero-dimensional particles. They experience no dilation, no time. No space. Therego, this might answer your question? ...0000 ...0000 N=0000 ...0000
See, this is why I dont like SR sometimes. It places limits which I dont want to accept might exist. Of course I shrug most of them off as mathematical limits...but still...if you wish to think outside of the box, you have to disregard many scientific theories alltogether and that makes me look either stupid or arrogant, and I hate that...Please Register or Log in to view the hidden image!
That's not the reason. All relativistic equations for massive particles reduce to the same equations applicable to photons for speeds very close to the speed of light. Massive objects cannot accelerate to the speed of light for the reason that to accelerate them to that speed would require an infinite amount of energy. Photons, though, have no rest mass, so they always travel at the speed of light. Time dilation doesn't come into it. If something starts 13 billion light years away and travels at the speed of light, it will take 13 billion years to get here. You don't even need relativity for that. Light can be gravitationally red or blue shifted, just as it can be Doppler shifted. Not only is light subject to relativity, it underlies the whole idea of relativity in the first place.
What is called time dilation is caused as matter approaches light speed. Photons are waves, and not particles, and always travels at light speed. However light speed is not always 186,282 mps and even glass can slow photons down to half that speed. With an electric current, what you put in at one end is of course not what you get out at the other end. The process of electron transfer results in an energy loss that we call resistance. A similar process happens in the galactic medium with trillions of interactions per billion light years, but it is believed that whereas electrons can lose energy, photons cannot. They cannot lose speed but they lose energy by redshifting. The further the distance, the more the energy loss, the more redshifting. Inside a galaxy, the medium is far denser so photons can lose more energy over far shorter distances.
No. Photons are particles with wave-like characteristics when observed under the right conditions. Very good. You are almost correct. Again, very good. I'm proud of you. Oh. So close. You just said that they can't (which is wrong) followed by "they can" which is right. And what do interactions have to do with an individual photon losing energy? In your glass example, the photon that emerges is not the photon that went in. The photon that enters the glass is absorbed by a valence electron in an atom and re-emitted to be absorbed again. The resultant photon is not redshifted (has the same energy as the one that entered). You do know that the energy of a photon is inversely proportional to it's wavelength, right? E = hc / wavelength Your first sentence is correct, but not because of what you said next, which is nonsense. Photons are redshifted (lose energy) due to the relative motions of the source and observer (either doppler or cosmological) or by climbing out of a gravity potential. Do not confuse fluorescence (in which a photon is absorbed by an atom causing a longer wavelength - lower energy - photon to be emitted) with redshift.
