Fermi's Paradox

For decades astronomers have discussed what the call “Fermi’s Paradox”. The famed physicist had once shown mathematically that even without faster than light travel any advanced civilization should be able to expand throughout the galaxy within the span of 4 million years. After doing that calculation and showing it to his colleagues, Fermi is said to have looked at the night sky and asked: “So, where is everybody?” Fermi’s paradox is that simple question, if there is other intelligent life out there why have we heard nothing from them? Why is there no evidence of their existence we can spot? This debate remained lively till our own time and has sparked the creation of the SETI and METI institutes.