How can light not lose momentum when traveling through glass

[Lincoln]

In fact Einstein derived momentum form energy-mass relationship. If mass is energy then energy is mass. E=mc^2 and so p=mc=(E/c^2)c=hf/c. However if we admit that photon has mass then we contradict mass/velocity relationship of SR. Therefore we admit what is convenient.

Your logic is wrong because you misuse equations.

E = mc² is properly correct in a rest frame. [There is a pedagogically-disreputable idea called relativistic mass, but I won't talk about that here unless forced to.] The actual equation is:

E² = m²c⁴ + p²c²

Further, p = mc isn't correct. p = mv for massive particles and E = pc for massless particles.

This is the source of your confusion.

[gerhard]

The idea that light has no mass is complete nonsense. If Gravity has an effect on light, then light has an effect on gravity. They absolutely must be related to each other or light could never have an influence on mass.
since mass influences light, light influences mass. The person that shoots this down had better have a good way of explaining, because any contradiction would mean that action is not equal and opposite. (please dont nitpick on my use of equal and opposite rather than equal but opposite. It's a habit.)

Unless whatever causes gravity bends the light.

[gerhard]

of course light has mass or it couldnt be influenced by gravity.

I googled this out of curiosity, the answer I found may be of interest to you:

strong gravitational fields may not be able to interact with light but they do change the shape of space-time. Light is responding to the curvature in space caused by gravity not the because gravity is 'pulling' on it.

So gravity doesn't influence light directly, it changes the shape of space itself, and since light travels in space, it effectively changes the shape of the path that light is taking.

Should have read this first before commenting, good explanation, and Lincoln is quite right.

[niiiick]

Due to the form and style writing you have exerted into your question, I do concur that you are acting as if light has mass. Light is the only known form in the universe that does not have mass. Light will pass through glass without slowing down due to it having no mass for there is no way it can slow down. Now that I have explained this, the answer to your question poses another question. Why does light not pass through a solid wall? This of course is due to many reasons. One of these reasons is the wall can absorb a certain frequency. This frequency may be light. Radio-waves can pass through the solid wall, as the wall may not be able to absorb that specific frequency, so the radio-waves can pass freely through the wall. I hope this reply answers your question, which I found deeply fascinating.

[scienceman3]

well light dosen't loose velocity when passing through glass because light waves are so small that they will miss the atoms also light has a constant speed of 600,000,000 km/sec so it can nevery loos velocity