UFOs are all the rage (actually, renamed unidentified aerial phenomena or UAPs). The House of Representatives is even holding hearings on the subject.
What goes around comes around.
When I was a teenager, I immersed myself in UFOs and Project Bluebook.
I guess my primary takeaway was, why would any intelligent species want to perform a colonoscopy on a poor, white guy in Mississippi?
If they are here, what are they hiding from? Compared to them, we are still in the technological stone age.
The best argument as to why they are hiding would be Star Trek’s prime directive not to interfere, but then, they are not going to interfere.
We have a very, very, ginormously-big universe (“billions and billions”). We have not been emitting radio waves for long, so there is an extremely limited area that can “see” us, and it is unlikely someone is just passing by.
I (following Stephen Hawking) also think that an intelligent alien species could be an existential threat to humans, so, on the whole, I would tend to not try to engage them.
However, very low probability occurrences do happen – I don’t see any dinosaurs anywhere and there are all these pesky mammals running around.
Find the humans.
This is a galaxy that looks a lot like our Milky Way.
Our galaxy contains some 100-400 billion stars and is some 105,700 light years wide (some 621,400 trillion miles)
It is estimated there are some 100-200 billion galaxies in the universe, which is some 547 billion trillion miles wide.
If we began transmitting radio waves, say in 1844 when the telegraph was invented, and assuming advanced aliens can pick up very weak signals, radio waves have now propagated some 178 light years from Earth, or a diameter of 356 light years, covering some 0.3% of the galaxy (treating the galaxy as a flat circle) and an infintesimal fraction of the universe.
The closest major galaxy to us, Andromeda, is 2.5 million light years away, so it will be a while before they hear from us.
Conversely, if we are hearing from them for the first time, the signal began 2.5 million years ago, and a lot has probably happened to them since that time.
For aliens to be here, they have to either just have been passing by or have been within the volume of our radio signals with enough time to react and get here.
The closest star is “only” 4.2 light years away (that’s about 24 trillion miles). If there is life there and if it is sufficiently advanced, they probably have heard us. It is not clear that they have had time to get here. Travelling at the speed of Voyager, some 35,000 miles per hour, it would take them some 82,000 years to get here.
Now, if they have dilithium crystals ….
Not holding my breath.