The sun that you may be watching right now isn’t exactly the sun at it’s present state. Yes, We are not viewing it live! It’s 8 minutes older than what our eyes are sensing! Surprising…But true.
We see something when the light from that object gets reflected to our eyes. Now, as the speed of light is very very large and the distance generally is meagre as compared to the travelling capabilities of it, the time delay due to conveyance is of least importance. But, imagine a situation in which even the light is not on time if we wish to see something. Obviously, it cannot be a case with anything in our dear Earth. So, the next big thing to be looked upon is the night sky. The distances involved there are so large that the numbers will not make sense. Only few of us pay heed to those un-interesting zeroes if they exceed even a modest 10(10000000000).
Upon following simple mathematics, it can be easily found out that an object more than 3 crore(dist. travelled by light in 1 sec.) kilometres away will take more than one second to present itself. What about the objects farther away in exponential terms? Such is the case with the Sun. Being 240 * 3 crore kilometres away, it needs 8 seconds from the light out there to reach our eyes. If anyhow, it(the sun) gets off-track, or just stop emitting light, we’ll be able to observe that change only after 8 minutes. Such is the constraint of light!
Uptil now, we were talking about the sun. What about the infinite number of galaxies that are hung beautifully in the sky today? Some of them might have ceased to exist today, or maybe, what we are seeing today might be the state of them when the earth was in it’s infancy. Ah…So very interesting.
The second thought that comes to my mind as I discuss this topic is through this phenomenon, can there be a way to peep into the future? Could travelling faster than light would capture that incoming light wave from the future? If it is possible…the results would be extremely exciting. And that’s why… it’s interesting.