So where is everyone? This is Fermi's paradox, if you haven't heard about it before, I'll just leave the quick run down. The universe is 13 billion years old, Earth is only 4 and all of human civilization has occurred in around 12000ish years, so any Alien species has a good chance of being ahead of us right? Colonizing galaxies and all that. But we haven't seen that, there's no evidence of it, paradox.
There are some theories that explain the paradox such as great filters but it's all theoretical as we only know of one way life came about and in a universe as large as ours, who's to say it's the only one.
@ToaNoah_Wafflemeister Aliens could break all ideas we've had in the past. If we find the remains of Aliens, it could be our doom (great filters), if we find an advance civilization, they could teach us things we'd never have known previously.
@meepinater we most likely would not attack them unless provoked, neither would we capture or experiment on them as they would often exchange knowledge and information with us. There is very little to be gained from attacking visitors to Earth or going to another planet to attack aliens, the energy required for these trips is more valuable than whatever we can gain from attacking or inhumane experimentation.
That was a mouthful to write.