The Fermi Paradox
The great Italian physicist and Nobel Laureate Enrico Fermi asked the seemingly innocuous question “Where are they?” in response to a luncheon conversation with colleagues about the oddity that no extraterrestrial sentient beings had contacted us Earthlings yet. This question is commonly known as Fermi’s Paradox.
Notwithstanding the obvious rejoinder that ETs (aka bad hombres) are currently occupying the White House, Fermi’s question has obvious merit, given the large number of habitable planets circulating around the immense number of stars we know exist in each of the immense number of galaxies we can and do observe in the Universe.
Put simply, if we can see (detect) those planets, some of which we already know to be habitable, then the ETs can in principle see (and detect) us. Why haven’t they reached out, or even colonized us?
There are over 20 possible explanations given in the Wikipedia article linked above, but three that jump out at me are that we have only begun to transmit outbound, and have only begun to listen inbound, and anyways, travel times are quite long and clearly one way, with a possible poor payout for our ET friends upon arrival. Maybe we just aren’t worth visiting, or by the time the aliens get here, we will have extinguished ourselves.
On the other hand, maybe we have already been visited by more primitive life forms capable of piggybacking their ways to Earth via comets, asteroids and the like.
Such life forms are called extremophiles, life forms that can withstand extremely hot, highly acidic, and/or high pressure environments unthinkably hostile to more complex life forms such as ourselves.
One interesting example of extremophiles is the lowly but fascinating millimeter-sized critter called tardigrade featured above.
Tardigrades can survive extremely low temperature, low pressure and high radiation environments, such as outer space.
Additionally, tardigrades can go into a suspended “life” state (cryptobiosis) that allows them to “die”, and then be “reborn”, with a few drops of water.
What to Do When The Aliens Call
Michael from VSauce addresses humanity’s apparent lack of preparedness for a possible alien invasion, and how the United Nations might get involved, should one occur.