What happens when we slow down while travelling at speed of light?

Question

When we travel close to the speed of light, time would move slower than for someone who is not moving. Interesting thing is both observer's clocks were running slower than the other when they look at each other.

My question is what happens when we slow down while travelling at the speed of light? Do we see other observer suddenly dead?

This is basically another way of describing what is known as the Twins Paradox and the explanation of that is in this answer to a similar question. — StephenG - Help Ukraine, Jan 11 '18 at 22:28
On the verbiage used, how exactly does one slow down while going at a constant speed? — Kyle Kanos, Jan 12 '18 at 00:50

score 1 · Accepted Answer · answered Jan 11 '18 at 20:34

There are a few things that are not possible in relativity -

1) Any massive body can not move at speed of light.

2) Even if it did, it could not slow down slowly.

These are probably limiting cases in relativity and I would not mind also considering them safety net for relativity.

3) Even ignoring above, any two observers, both moving at speed of light in same direction wrt a third observer, are not moving at all wrt one another. So if one of them slow down a bit, will see the other left behind (or pass ahead) with that bit of speed.

Only thing that we understand, and have formulated till this time, is relativity. We do not seem to have means to understand (let alone formulate) absoluteness, even if there was such a thing. But various paradoxes indicate, there could be. So, keep thinking.

What happens when we slow down while travelling at speed of light?

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