What Was It Like When Life In The Universe First Became Possible?
“We still don’t know how life in the Universe got its start, or whether life as we know it is common, rare, or a once-in-a-Universe proposition. But we can be certain that life came about in our cosmos at least once, and that it was built out of the heavy elements made from previous generations of stars. If we look at how stars theoretically form in young star clusters and early galaxies, we could reach that abundance threshold after several hundred million years; all that remains is putting those atoms together in a favorable-to-life arrangement. If we form the molecules necessary for life and put them in an environment conducive to life arising from non-life, suddenly the emergence of biology could have come when the Universe was just a few percent of its current age. The earliest life in the Universe, we must conclude, could have been possible before it was even a billion years old.”
When the Universe was first born, life was absolutely impossible. There were no planets for life to reside on; there were no organic molecules to self-replicate; there were no energy gradients or sources of heat and light; there weren’t even heavy elements or neutral atoms. In order for life to exist, the Universe had quite a bit of work to do.
Our Earth formed after more than 9 billion years of cosmic evolution, and life began on our planet shortly after that. But there’s no reason to believe that Earth is the only world with life on it; in fact, if we put everything we know about the Universe together, many other locations should have gotten there billions of years earlier.
Here’s the cosmic story of when life could have first arisen in the Universe, and it comes not only before us, but before most people have ever dared imagine.
Will Scientists Ever Discover Life Without A Home Planet?
“Either life began on Earth with a complexity on the order of 100,000 base pairs in the first organism, or life began billions of years earlier in a much simpler form. That could have been on a pre-existing world, whose contents migrated into space and eventually came to Earth in a great panspermic event, which is certainly possible. But it also could have been in the depths of interstellar space, where the energy from the galaxy’s stars and cataclysms provided an environment for molecular assembly. It may not necessarily have been life in the form of a cell, but a molecule that can collect energy from its environment, perform a function, and reproduce itself, encoding the information essential to its existence in the reproduced molecule, just might qualify as life.”
We talk about the origin of life on Earth with bated breath, wondering all the time how things occurred to make our planet unique. But within that big question lies an assumption that may not be true: that life on Earth originated on Earth itself. It’s entirely possible, based on what we’ve seen out there in the Universe, that life didn’t originate here at all. Rather, it could have come from a primitive, pre-existing world, or even from the depths of interstellar space itself. If it’s the latter case – interstellar space – then perhaps we don’t even require a planet at all to create the more primitive forms of life itself. Perhaps all you need is a molecule that encodes information, reproduces itself, and converts external energy for use in biological processes. And if that’s the case, the origin of life may bear very little resemblance to what life has evolved into today.
Could pretty much all places in the Universe, by the present time, have these ingredients that qualify as life? Let’s look at the evidence!