What is even more crazy is that we can actually look as far as the beginning of the universe just because of how long it takes for particles from the other side of the universe to reach us.
Sorry if questions don’t make sense…
Light moves at the speed of causality - C - so it does not experience time. Therefore light never changes. However, for distant extra-galactic objects, the space that the light is traveling through is expanding! Thus the wave property of light is stretched out as well. So what was once visible light is now so stretched out (in our reference frame) that our eyes can't detect it (that's why the night sky is black).
So yes, the light is finite. It itself experiences no change. The number of particles heading in our direction only changes when they encounter some types of mass, such as interstellar or intergalactic gad clouds.
If you want to know why light is not a particle (and also not a wave) check out the dual-slit experiments. Fascinating stuff.
C is coulombs
And casualty is a dead person
> light never changes
is wrong. A photon has a momentum, which can increase or decrease as it travels through free space.
Using general relativity, it's straightforward to define an affine time on a null geodesic (even if one cannot define a proper time on one), and a momentum that is a function of the affine time at each point.
The Lyman-alpha forest is a straightforward "laboratory" for this approach, which can calculate the Lyα absorption lines seen when a bright distant quasar or luminous Lyα emitter has atomic hydrogen clouds between the distant source and us (the absorption lines indicate photons with a very narrow range of momenta participated in hydrogen atoms' electrons transitioning from ground to the first excited state, with the later relaxation photons radiating in random directions). The pattern of such dark spectral lines tells us how redshifted the background light and earlier absorption lines are at each gas cloud along the way.
https://www.astro.ucla.edu/~wright/Lyman-alpha-forest.html
https://en.wikipedia.org/wiki/Lyman-alpha_emitter
And over much-shorter-than-cosmological distances, https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment
Much as the flat earth theories or the universe rotates around the earth, I suspect we don’t really get it yet and we’ll have other ideas in 300 years from now.
Just reading here about the theories of light, fundamentally we don’t understand what light truly is. Sure we have this theory and that idea, but these seem too complex and fragile to be really it - imho.
I mean no disrespect, and everyone can have their theories and opinions. But we shouldn’t forget the arrow of time continues and it’s still a long way to go.
I'm not an historian but the curvature of the world was probably explained away by some other phenomenon because, after all, the world is flat (for those experience curvature in times of flat Earth).
So to "experience" the curvature of the Earth, you first have to know the Earth is round. Much as our "bug free" software is only buggy once we find a bug, before that, the bug was a feature ;)
Similar the stars were explained away as holes in a black sphere surrounding the Earth: the light points in a night skies didn't lead to a universal acceptance of the Universe. It was telescopes that made us realize that those "holes in the sphere" were actually galaxies.
So my understanding would be, that it was Magellan circumnavigating the Earth that made folks actually "experience" the curvature of the Earth.
This might be being pedantic but I am trying to point out that "experiences" are related to understanding and perspective. Experiences are different in different contexts: hence my experiences are different to all those around me.
My interpretation of "experiences" differ according to understanding. An apple falling on my head might well have more to do with evilness of various gods than gravity before the invention of gravity. But even gravity is just another interpretation/explanation/myth to explain the "experience" falling apple.