Kinetic theory light

[nduriri]

By considering light as a part we deduce the radiation presser and the coefficient of reflection
http://www.gsjournal.net/Science-Journals/Essays/View/6551

[janoskiss]

Hi Joseph, welcome to IIS, and good on you for studying cool stuff of physics and astronomy.

A nice problem to tackle is to figure out how much distant starlight grazing the Sun would be deflected on the basis of only Special Relativity (SR), Newtonian gravity and the Einstein-Planck formula E=hf, and see if it agrees with General Relativity (GR) predictions (which you can look up).

The solar eclipse experiments of 1919 and 1922 were the first experimental verification of GR, but was it really GR or would have SR and Newtonian physics been just as good?

I actually don't know the answer. I attempted the calculations once and got sensible numbers but I was not thorough enough to draw a firm conclusion and it's been on my long list of things to do properly since. But if you could do it, that'd be awesome, and a really good learning exercise for any student of physics.

[rally]

So in this hypothesis - just how much faster can light travel than c when being gravitationally attracted ?

[janoskiss]

Light always travels at the same speed "c". But gravity affects its momentum: its colour (wavelength) and/or its direction of travel. So gravity can bend a lightbeam but it won't alter its speed. It's not really what we'd call a hypothesis any more. It's a very well established fact backed up by countless experiments and robust physical theory.

[rally]

Im only referring to what his particular paper states.

"When the light approaches the Sun its speed increases(c+c),"

Not sure if the Delta symbol will display correctly here

[Atmos]

Steve is correct, light can be changed but it cannot have its speed changed, although this does get complicated to explain when referring to refraction which is generally described as being the "slowing down of light within a material".

The author of this essay appears to be associating newtonian mechanics with photons, these two do not play well together.

[Zuts]

Maybe i'm wrong but I though 'C' was the speed of light in a vacuum. 'C' can slow down to 'C' - delta in other mediums, glass, water etc. In this case in that medium 'C' - delta would be the fastest possible speed.

In this case since light bending around the Sun would be very close to the Sun then since close to the Sun it is not a very good vacuum then light may slow down. Would this effect have to be taken into account in the calculations?

[rally]

5 days later and the OP with his 1st ever post hasnt bothered to reply to a genuine question about his Physics nonsense.

His 2nd only post is a link to the same thing in the middle of another unrelated thread
How about we delete this thread and remove him from ISS

[Atmos]

Photons must always travel at C, the reason C is talked about being the speed of light in a vacuum is that in a vacuum it is unimpeded. When photons move through another material they can appear to slow down (refractive index) but what actually happens is that their journey effectively increases. A photons slowing down is not so much them slowing below C, just that it takes them longer to travel the same distance (on a macro level; to us) whereas on an atomic level, light actually has to move a lit further to get through that medium due to molecular density and structure.



The OP may never come back but it opens up for "interesting" conversation if nothing else ;)

[rally]

Not really - Just another pseudo science troll pedalling nonsense

[janoskiss]

He could just be a young kid. There is no need to remove him or delete this thread. There is nothing sinister in what he linked.

@Atmos & @Zuts
Light slowing down due to refractive index is a tricky topic. There are classical and quantum mechanical ways of looking at the phenomenon. Here is an excellent discussion on the topic (from good old Sixty Symbols): https://youtu.be/CiHN0ZWE5bk

[sjastro]

I lost interest in this paper after this line.



In Newtonian physics energy and momentum are separate concepts but in special relativity they are inextricably linked through the equation,

E^2=(pc)^2 + (mc^2)^2
E is the total energy, p is the momentum, mc^2 is the familiar term relating the energy of a particle to its rest mass m, c is the speed of light.

For a photon m=0 the equation reduces to E = pc or p= E/c.
This is the same as the above equation in the quote but is deduced from the condition that its rest mass is m=0.

If photons have non zero rest mass it can never reach the speed c much less surpass it as it would have a relativistic mass M = m/(1-(u/c)^2)^0.5 where u is the speed of the photon.
Put u=c and the relativistic mass M becomes infinitely large.

This is what we observe in particles accelerators such as the LHC.
The relativistic mass of a proton increases as its velocity increases.
Protons can be accelerated up 99.9999999999% (give or take a few decimal 9s) the speed of light at the LHC but can never reach the speed c.

Since photons have zero rest mass the rest of the paper makes no sense.

The gravitational bending of light comes from the Schwarczschild metric which is an exact solution to Einstein's General Relativity vacuum field equations.
The theoretical value agrees well with measurements of "sun grazing" photons.
Importantly the result is independent of the photon's wavelength hence it is not related to mechanisms such as refraction.