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### Why Speed of light in vacuum remains constant? [duplicate]

I know that the speed of light remains constant irrespective of whether the light source is moving or not. But it's very difficult for my brain to visualize it. Light has dual characteristics, i.e. of ...
5k views

### Can a photon get emitted without a receiver?

It is generally agreed upon that electromagnetic waves from an emitter do not have to connect to a receiver, but how can we be sure this is a fact? The problem is that we can never observe non-...
219 views

### Why a body can not be accelerated to speed of light in vacuum? [duplicate]

Well i know that it needs infinite energy..but the term infinite is itself not physical so i am not satisfied with this answer ...but what would happen if we provide a constant acceleration to an ...
3k views

### Why can't we break the speed of light in vacuum? [duplicate]

I was wondering what could be a possible reason/reasons because of which we cannot break the speed of light barrier. I was reading this where they stated that, Quantum Action Is 10,000 Times Faster ...
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### Light cone argument for speed of light

Using light cones to state that nothing can travel faster than light to me seems like a flawed argument. (I understand other reasons why the speed of light cannot be broken.) However, it seems to me ...
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### Why does the speed of light in vacuum never change? [duplicate]

why does the speed of light in vacuum never change? Under any circumstances, The speed of light in vacuum never change, why?
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### Different approach of time dilation explanation

Suppose you are going to a distant star, and there is an observer on earth. Usually the answer to the question how long would it take to travel to a distant star is explained this way : You cannot ...
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### We all accept/believe in $c$. But what happens when light travels away from the center of gravity of a heavy star? Does it slow down?

I'm basically trying to understand a mysterious characteristic of the universe. Why light has to travel at $c$? I understand and accept that from experiment. Not arguing that it does not. Just saying ...
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### Can we tell when an established theory is wrong?

I was reading the following answer from this question: In physics, you cannot ask / answer why without ambiguity. Now, we observe that the speed of light is finite and that it seems to be the ...
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### Is a finite lightspeed necessary for cause and effect to exist? [duplicate]

In this question I asked in somewhat unclear (unclear enough to be closed) fashion about the relationship between an infinite speed of light and the existence of cause and effect. In thís question, I ...
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### Can the constancy of the speed of light in vacuum be derived from a deeper theory?

Einstein's second postulate of special relativity is: The speed of light in vacuum takes the same value ($c$) for any observer in an inertial frame of reference. I know there is a lot of ...
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### What happens with time when we travel at the speed of light? [closed]

I always wonder how time is related to traveling at the speed of light and what actually happens when we travel at the speed of light. Why does time slow down and what can be the physical explanation ...
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### Holding the total velocity below speed of light

If a hydrogen atom accelerates to near the speed of light, the total velocity of the system must not exceed that limit. Even if the electron has no net angular momentum around the proton, as it could ...
When we derive gravitational potential it is dependant only on (rest) mass $m$, but i have seen a derivation of gravitational redshift equation placing relativistic mass $\widetilde{m}$ instead of ...