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Life Could Have Evolved 15 Million Years After the Big Bang, Says Cosmologist
KentuckyFC writes "Goldilocks zones are regions around stars that are 'just right' for liquid water and for the chemistry of life as we know it. Now one cosmologist points out that the universe must have been through a Goldilocks epoch, a period in which warm, watery conditions could have existed on almost any planet in the entire cosmos. The key phenomenon here is the cosmic background radiation, the afterglow of the Big Bang which was blazing hot when it first formed. But as the universe expanded, the wavelength of this radiation increased, lowering its energy. Today, it is an icy 3 Kelvin. But somewhere along the way, it must have been between 273 and 300 Kelvin, just right to keep water in liquid form. According to the new calculations, this Goldilocks epoch would have occurred when the universe was about 15 million years old and would have lasted for several million years. And since the first stars had a lifespan of only 3 million years or so, that allows plenty of time for the heavy elements to have formed which are necessary for planet formation and the chemistry of life. Indeed, if live did evolve a this time, it would have predated life on Earth by about 10 billion years."
I always wondered what the point was with considering panspermia. If life could have appeared anywhere in order to make it to Earth, it could have just as easily originated on Earth to begin with. There's nothing miraculous about Earth, but there is nothing sub-standard about it either.
It would be interesting to know if terrestrial life started elsewhere, but what problems does that hypothesis solve? The only one I can think of is why all almost all Star Trek aliens look like humans with different foreheads.
The problem that panspermia theories are supposed to "solve" is the ease or difficulty of "bootstrapping" life --- how likely is it to get self-replicating, self-organizing complex systems out of simpler chemical precursors. In the case that this is "really really unlikely," then panspermia allows the earliest forms of life to occur only in a few rare cases, but then spread to populate more of the universe. On the other hand, this is unnecessary if the initial chances of life formation are reasonable (given a few billion years and a planet-sized cauldron of random chemical soup). So far, scientists in the lab have been able to generate a lot of life precursors (amino acids, etc.) under "early Earth" conditions, but not demonstrate the "leap" to self-replicating systems; however, this may not prove too much, since scientists haven't had a billion years and a planet-sized petri dish array to try everything out.