"Hello! I'm Julia Child. I'm in my own kitchen today and I'm boiling up some primordial soup. And there is a primordial soup machine. We're doing a recipe for the chemical building blocks of life, today, at the Smithsonian..."
"Now I'm going to turn the machine on, and you're going to see how it works. There we go! Now here, here is the vapor is being vaporized, up here, goes through this tube, and gets zapped by these electric sparks. And the atmosphere falls down, and is condensed, and falls down, and is recirculated again. Now I'm going to turn the machine off."
"Well, pretty soon, with this continual exchange from soupy sea, to gaseous atmosphere, and down to soupy sea again, always going through shocks of energy, we're going to be making almost all of the chemical components--the building blocks of life..."
"Of course, the next step is, how to put these chemical building blocks together. Can we make life? And is this the way life began on this Earth? Who knows? And is this same process taking place on other planets? We don't know yet! But according to the laws of probability, it certainly could be. So that's all on the chemical building blocks of life and primordial soup. This is Julia Child, bon appétit!"Wait, was the the real Julia Child? Wait, wait--who is Julia Child? (Video link: "Primordial Soup, with Julia Child (1976).")
This presentation will address the origin of life on Earth.
First, coming up with a working definition of life.
Ever play this board game as a child? Just what was goal of this game? If any of you are parents, then the ultimate goal of this game is to keep children occupied for a good thirty minutes or so, no matter who wins, or what happens during the game itself. Let's start with a working definition of what something living does (as opposed to what a living thing is): it should manipulate its environment (eat, build, destroy, etc.) in order to grow and make a new generation of things that can manipulate its environment.
In order to do things that livings things do, and more importantly, to make sure that a future generation is able to continue doing these things requires a lot of instructions to be stored. On Earth this information is typically encoded in long, complex sequences of carbon molecules (although it is speculated that some other types of chemicals might instead encode this information).
One last thing to add to our working definition of life--in order to survive changes in the environment, a living thing should be able to adapt, either in its own lifetime, or through changes in successive generations. Because conditions on Earth change over time, then living things on Earth have also changed over time.
Second, a timeline for how life arose on Earth. There are two things to consider here: first is that initially these steps take a long time to happen, but each successive step takes a shorter and shorter time to occur, so the rate of change speeds up over time. Second thing to consider is that this sequence of events is a hypothesis, and we will present evidence for each step, whether through recreation of similar conditions, or fossilized remnants--but to be completely honest, there will be one step in particular that has yet to be recreated or remnants to be found for, and we will be sure to point this out.
Atoms have a tendency to hook up with other atoms to make simple and complicated molecules, as long as there is enough energy and enough time. It is not difficult to have "building blocks"--simple molecules--assemble naturally in a short amount of time. This isn't life yet, but it's a start, and can be readily demonstrated by recreating conditions expected of early Earth, as did Julia Child in the video clip at the start of the presentation.
Eventually longer and longer molecular chains will build up, and at some point will begin to manipulate the environment and make new generations of itself. This is the step that there is no fossil remnants for, and has yet to be observed in nature or deliberately created in the laboratory. But this is actively being pursued, and as to whether this can at least happen in the laboratory or be observed in nature, as Julia Child points out, "who knows?"
Life gets more and more complex from here, as single cell organisms progress to larger organisms made of many, many cells working collectively underwater. Living things start looking less like stuff that will make you sick if you ingest it, to more tasty and nutritious forms about 0.6 billion years--relatively very recently. So if you ever build a time machine, and forget to pack a lunch, don't go much farther back in time than this, or you'll starve to death.
Now each consecutive step for life to become more and more complex will happen faster and faster. Not long after complex life started in Earth's oceans, complex life arose on land, as determined by fossilized remnants.
And then not much longer after that, life on land begins to become complex enough not only to become more populous, but to radically change its environment to do so.
So it took a while for simple life to arise from atoms and molecules, and then become more and more complex from the oceans, onto land, and so far, us.
And we humans in terms of at least being capable of technological civilizations are extremely recent newcomers, only 0.003 billion years ago. In the subsequent presentation where we consider the possibility of life elsewhere in our galaxy (and how we might communicate with them), keep this timetable in mind. While we cannot be sure that life elsewhere (if it exists) would arise in the same way as it did on Earth, it is plausible that it would take approximately the same amount of time for simple life to naturally arise, and the rate of change in the complexity of life forms would accelerate with each successive step.