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Speed of light is not limited - our Universe is.

The consequences of the special theory of relativity are Time dilation and Length contraction - let us try to understand a bit about them:

Time dilation:

When a body is traveling from one point to another in space at near light speeds, the body can arrive the destination in lesser time than what we generally (intuitively) expect. This is called time dilation. Below is an example:

Assume that we are required to travel a distance of 5 light years. Even if we were to go at light speed, our intuition says it has to take 5 years. So we will be older by 5 light years upon reaching the destination. But it does NOT work that way. In fact, it is completely possible that we cover the distance in 3 years. So we will age 3 years only.

Now, if we are covering a 5 light-year distance in 3 years - it may seem like we are traveling at more-than light speed. But this should not be possible right? Is this some kind of violation? No. So what's happening exactly here? Here comes the other consequence:

Length contraction:

From POV of the us traveling at near-light speeds - we are not actually covering a distance of 5 light-years. For us, the space actually shrinks - or contracts, so we can do the total travel in 3 years. This act of shrinking of space is called 'Length contraction.'

How much exactly the we age, and how much the space shrinks can be determined using formulae - they are referred to as Lorentz transformations.

So, at near light speeds, time and space both bend to make the way for us. But what happens at the exact light speed? 

POV of light: 

Now, we can't use the Lorentz transformations at the exact light speed because we get into zeros and infinities. Ideally, it's not supported. But let's try extrapolating the behavior of near light-speed to the light-speed (of course, still we are going for zeros and infinities - but yeah let's just do anyways)

Length contraction: At near light-speed, if the speed keeps on increasing, the space continues to shrink further and further. If we extrapolate - at the light speed, the space shrinks entirely that it just becomes a point. Yes - in the light POV, it is not actually traveling from 'a' to 'b'. It just is already there at 'b'.

Time dilation: The proper time continues to be lesser and lesser at near light speeds. For light - it does not take time at all! Of course we can easily see now - if there's no distance to travel, how it can experience any ticking of time? 

The above affects also kinda explain the postulate of special relativity that light speed is always the same irrespective of our speed. Assume we are traveling at 0.8c (c being the speed of light), then if we measure the speed of light, it won't be 0.2c - It is still c! 

We can see why this works - irrespective of how fast you go - light is already there. In other words  - whether it is traveling from the sun to the earth - or from the light bulb to the chair - it just is nothing for light. It just exists, almost instantly from the source to destination.

Why speed of light is finite?

We already have experimental evidence for the speed of light. It is true. No denying that. But why is it that we are measuring a finite value for something that can travel from one end of the universe to the other in just zero time? The limit is not actually on the light - it's on our universe.

The light speed is not actually 'speed of light' - it's actually referred as 'speed of causality.' It is the maximum speed at which any information or signal can travel in our universe. The light is just bound by that.

This limit on the causality is a characteristic of our universe. It is entirely possible that there can exist another universe where the speed of causality is twice - or ten times - or half of ours. In that case, the light in that universe will travel at that speed (given that light exists in that universe).

So yeah - it's not that light has limit on its speed. Universe has limit. 

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