In a post of a couple of weeks ago, I wrote on the idea of “panspermia”, which proposes that life arose on Earth because Earth was seeded with life from elsewhere in the universe (click here for that post). This idea came in response to the demise in the nineteenth century of the theory of spontaneous generation, which said that life naturally arises from inanimate matter. Spontaneous generation was an idea that dated back to Aristotle and beyond.
Under spontaneous generation, life would have existed for as long as matter existed (forever, in Aristotle’s view, since he thought the universe was eternal, having no beginning). Well, advocates for panspermia, like Hermann von Helmholtz and Svante Arrhenius, thought the same thing. Both men seemed to view matter, and hence life, as eternal. It makes sense, then, said Helmholz, “to ask whether life ever arose at all.” If life is eternal, said Arrhenius, then “it is useless to inquire into its origin.” Therefore, whereas life did not arise from inanimate matter — you would never see life springing up from sterile mud in a laboratory, for example — the universe was full of the seeds of life being passed from world to world, and always had been.
These nineteenth-century men lived hundreds of years after the dominance of Aristotle’s ideas in science had come to an end. But those men, and much of the scientific world, hung on to the idea of an eternal universe. Nevertheless, the eternity of the universe was already a dying concept when these men were pursuing their science. The study of heat was showing that the universe is not eternal — click here for a four-part series of posts from last winter about “Beads, Doom and the Multiverse” that discusses all that.
Then, of course, in the twentieth century, came Albert Einstein, Fr. Georges Lemaître, Edwin Hubble, the expanding universe, and the Big Bang theory. An expanding, Big Bang universe is not infinitely old, not eternal, and has a beginning. In 1871, William Thompson had initiated the idea of panspermia because science was indicating that the Earth was once “a red-hot melted globe on which no life could exist.” With no spontaneous generation, life on this Earth must have come from elsewhere. Hence panspermia. Under the Big Bang, however, the universe was once very small, and far, far hotter than any molten globe. Indeed, it was so hot that even atoms could not exist. The remnant heat from that early, hot state is still present within the universe; astronomers study this “Cosmic Microwave Background” (mapped above) to learn about the Big Bang.
The universe is expanding. It is cooling. It has a finite age of about 14 billion years. This really poses a scientific conundrum as regards the origin of life. The universe is not eternal, so neither then is life. Thompson said that Earth had to initially be lifeless because it was too hot. Well, the universe was once far, far hotter! Therefore, life cannot be even as old as the universe. Life must have had an origin within the universe — we are here, after all — and yet it does not spontaneously generate from matter. We do not see life originating from inanimate matter in nature, and we cannot generate life from inanimate matter in a laboratory.
This incredibly vast, but exceedingly infecund Universe, is a puzzle. Life had to arise from inanimate matter at some point after the Big Bang, but (obviously) through a process that does not occur regularly and that eludes our understanding.
For most of history, we were confident that life was simply an outgrowth of matter and thus co-eternal with matter; or, that life simply pervaded the universe and thus was co-eternal with it. Now, we have no idea. Yes, people may go on confidently about life self-assembling in warm pools or whatnot (a sort of limited spontaneous generation), but such things have never been observed and there is nothing like a complete hypothesis to explain how it would happen. Never in the history of science have we been so in the dark — or, perhaps, so cognizant of how in the dark we are — regarding how life comes into existence.
