We, human beings have looked up at the sky for hundreds of thousands of years in wonder. In the last few hundred years, ” Why isn’t there any life on other planets?” , ”Since the universe is billions of years old, there must be many advanced civilization, why haven’t we found any evidence of them?”, etc.
We have looked at the edges of the universe, galaxies, other planets, etc to look for life on other planets but haven’t found any. We even build of our powerful and advanced machines like the Hubble Telescope, International Space Station, etc in search of them but the result is always disappointing.
So there is a theory which I thought might be a solution to this problem. The universe is extremely vast. It is about 93 billions light years across in the observable universe while about 20 trillion km in the whole universe. So this means that if we are looking at an object 1 million light years far away, the light needs to travel 1 million light years before reaching us which means that we are seeing the object what it was 1 million years ago not what it is right now. It may be erased out of existence right now but we won’t notice or see it until 1 million years later. This applies even with billions, trillions of light years and even for small distances like 1 km , 5km or 0.000000000001 m.
Even for objects 1 km apart, we are not seeing the object instantly, it takes a negligible very small amount of time for light to reach from one place to another in 1 km distance. It takes about 3*10^-5 seconds for a photon to travel 1 km so when we are looking at object 1 km far away, we are seeing it what it was 3*10^-5 seconds ago not what it is right now.
The conclusion is that nothing can travel faster than light through space. So even our radio waves that are sent into space takes time to reach to other planets and solar systems. Some physicists said that our radio waves have reach around 200 light years in radius in space. But 200 light years is nothing compared to the ever-expanding and enormous space.
Say, for our purpose, let us assume that we have some alien civilizations in our 200 light years radius and they detect it, it will take around 200 years to reach us even if they are moving at light-speed. But, in reality, alien civilizations may be very far away and anything with mass can never achieve light speed.
Also, another conclusion is that alien civilizations may exist and the reason why we can’t detect their radio waves or see them is that they are very far away. Suppose, an alien civilization is 25000 light years away, when they look at us, they will be seeing us what we were 25000 years ago. So they might think that we are too primitive to communicate with. Or another possibility is that an alien civilization may have detected us and even if they are on their way, it will take many years to reach us or send a message and receive it.
Another possibility is that some alien civilizations may become advanced in the last few thousand years but they are millions of light years across. So even if we look at them, we are seeing their planet millions of years ago when the might not even evolve or life may not even start to exist.
Knowledge Glutton 