Before anyone comes for me, I grew up southern baptist – went to a private christian school & was homeschooled for a few years. The extent of my “science” education when it came to evolution & the origin of the universe was “if we came from monkeys why do monkeys still exist?” and “look at this galaxy that’s shaped like a cross, isn’t god amazing!!” I’m an atheist now and would like to have some sort of understanding of how our world came to be, but trying to figure it out as an adult with no real foundation has been incredibly difficult, and none of it’s making sense. I also know I’m asking a lot as all 3 of those subjects are pretty extensive, so if you know any good videos or books I’d love some recommendations!
In: Biology
I’m trying to be really clear about what we actually *know*, and what we’re just assuming that means. A good scientist will never tell you this is definitely how it all happened. They’ll simply say this is the best idea we have right now, and if they see something that contradicts this idea and can’t be explained, they will change their mind and think of a better idea. That’s science: think of an idea, come up with a test that would tell you if the idea is right or not, and see if it’s right. If the idea passes the test, test it another way. If the idea is wrong, come up with a new idea that does explain all the tests.
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Evolution: creatures have genes that determine what they are. They get most of them from their parents, but sometimes various factors make something change.
If you’ve got 10 animals of some kind, and one of them happens to grow up with a mutation that helps it find food more easily, it will have more kids than the other animals. Maybe next generation she’ll have 3 kids that live when her fellow animals have 1 or sometimes zero kids. Now 30% of them are hers and have that adaptation. Next generation they all do well, too, and so on. Eventually all the animals like that have this adaptation. All the others eventually had no kids one generation and they’re all gone now. This concept is “natural selection”, that the animals that do better, *do better*. There’s really nothing more to it than that.
Evolution (its full name is “evolution by natural selection”) is just the idea that this is how **all** the life ended up how it is, which seems to check out as far as we can tell. Everything has this genetic code and it makes sense that the ones that survive better do so.
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Big Bang: we don’t know how it happened. What we truly know is that everywhere we look with telescopes, far-away stuff is getting further away. The light from it is getting stretched, and it stretches more the further away it is. It’s moving away from us, everywhere. That means in a year it will be further away… so a year ago it was closer, right? Carry that to its naive conclusion, and at one point, everything was really close. This discovery (cosmic expansion or Hubble expansion, they call it) is what led us to think: maybe this whole universe started with a big… bang of everything blasting out into a universe. It was a fun idea.
What led us to **really** think we were on to something with this big bang idea is the discovery that no matter where you aim a radio telescope into the sky, a good telescope picks up this background noise in the microwave range. It’s almost the same everywhere, any “blank spot” in the sky has this noise. What’s more, if we calculate the amount of light stretching because of expansion that would lead to that microwave noise, it matches our other estimates for how old the universe is.
What we think happened was: when the universe was first banging (heh…), all the matter was so crowded up and soupy that light couldn’t just fly around like light does now. At one magic point, stuff spread out enough that electromagnetism could draw elections into orbit around protons (and make hydrogen!), and there was *empty space* for the first time. Right then all the light of the universe that was caught up in the soup was able to blast out for the first time, everywhere in every direction. And stretched out over billions of years, *that is the noise that we pick up everywhere*. It’s still here: it’s already everywhere so there’s nowhere else for it to go. We call that the CMB, the Cosmic Microwave Background. When we discovered that, this bang bang idea really caught on as the most reasonable explanation we have for this.
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Abiogenesis. My friend, we have no clue. We don’t know how it happened… we just don’t. There have been experiments that showed that if you just blast electricity (like lightning) at rocks in water through methane gas you can get it to create amino acids and stuff, and some of them created weird spherical structures that accumulated and “grew”… but as to how the first real living thing started living, we just don’t have the data to work with right now. All we know is that somehow, really simple life that grew based off a chemical inside (genes) that could change and grow formed, and from there on natural selection makes sense. But that initial starting point: we just don’t know yet.
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