- Does the notion that the first cell came from outer space hold any scientific merit?

- One of the ways in which origin of life researchers try to get around the insurmountable problems with explaining the origin of life here on Earth is to appeal to a delivery of life from an extra-planetary or extra-solar source. This is called panspermia and the idea is that life didn't originate on Earth but was delivered to Earth through some kind of transport mechanism. The problems with those scenarios are legion though. For example, if a bacterium is travelling through outer space, it’s going to be exposed to high-energy radiation, and its survivability is going to be rather short-limited. And once there is an entry mechanism, the frictional heating for something to travel through our atmosphere to arrive on the Earth would be so intense that it would sterilize any kind of organism that would be present in that delivery vehicle. So it’s very difficult to envision how life could survive that transportation, how it could survive entry into the earth. When those impactors strike the earth, huge amounts of energy are liberated, which would incinerate those life forms. So it’s a mechanism of desperation in my mind.