Did you know that the speed of light is around 3.00 × 108 m/s? For now, it is believed that there is nothing faster than the speed of light, which is why large astronomical distances are often denoted by light-years, the distance that light can travel in a year.
If we were to see a galaxy that is 100 million light-years away, we would actually be seeing how the galaxy was a 100 million years ago. The light from the galaxy would be light that traveled from that galaxy 100 million years ago and just reached our eyes. So technically, we would be looking at the past. Right now, in this very moment, the galaxy that we see would actually be 100 million years older than how we see it.
So if this is true, then isn’t everything we see in the past? Even objects that are much closer than 100 million light-years away still have some distance from our eyes. The infinitesimal distance that the light has to travel from these objects to our eyes is still greater than 0, meaning that everything we see has already happened.
It’s quite depressing to think of how insignificant human lives are. We will learn nothing about changes in the universe because by the time the updated light reaches our planet, humanity will most likely have already gone extinct. All we can do is peer out into the vast universe and simply oooh and ahhh at the marvelous sight.