20210907 : Mars and speed of light

The speed of light is 299,792,458 m/s. Or roughly, as we learnt in school, 3x10^8 m/s.

That's awfully fast. Incidentally, the fastest we can also communicate today. Can almost go around the whole earth once in a second.

They are planning to colonise Mars sometime soon. They have many challenges. One of the main ones is communication. You see, it will take a little over 4 Seconds to send a message back or forth. But thats the best case scenario - when Earth and Mars are closest. When they are farthest, it will be over 16 minutes. There goes the concept of "instant" messaging folks there. It's a different problem that the Sun will be inbetween to communicate anything.

Another interesting challenge is how to keep track of time. Mars doesn't rotate in its axis in 24 hrs. Days don't match. They have 2 moons- so there goes the concept of months. The earth revolves around the Sun almost twice in a mars year. So nothing cyclic matches. Yes, we can give earth time, but really, will folks become older faster because we on earth think that is what the definition of years, months, days are? 

That was a digression. Coming back to the main thought,.

When we look at a sight of the Sun just about to set, we are not looking at the sun. The Sun has already set. We are seeing history from 8 minutes ago.

Recently, scientists have discovered a mega super cluster. Incidentally it was discovered by a bunch of Indian astronomers and it's called Saraswati super cluster.

They estimate it is 4 Billion light years away.

It has been estimated that the entire galaxy is about 13 Billions years old. 

So what they have seen, is really glimpse at something in history 4 billion years ago. Wouldn't have a clue what it looks like today or if it's still there.

That's a pretty twisted thought.

Clearly, the speed of light is very very slow. We need something else to achieve anything at a cosmic scale...