1) where did the universe come from?
2) where did life come from?
3) where did humans come from?
1) Where did the Universe come from?
*Edit: this argument has grown in importance for me quite a bit over the last few months. Read this section as you will, but I am now actually more concerned with this question than with the other two*
I am personally less concerned with this question than with the other two. I think both Christianity and Atheism stand on equally weak footing here, and the reality is that both the going theory for atheists (the big bang) and for Christians (God did it) implies a state of the universe that we can't really hope to have any knowledge of. What rules would apply when all of existence was compressed into a point-mass? What new forces would we observe? What would time even look like at that point? I do think there's some validity to the "first causation" argument- i.e. if everything has a cause, then either time must go infinitely backwards, in which case we couldn't possibly have gotten to our current point because that would imply infinite time has passed, or there was some unmoved mover. However, given the implications of relativity, where time is no longer the universal constant, I find it hard to speak sensibly on the subject. If nothing else, I can say that I am not an expert, I can totally imagine a universe in which time does something crazy like going as e^(1/x):
|"The rate of change of time with respect to... uh...."|
2) where did life come from?
I'm definitely not an expert here. Not a biologist, not a chemist, and not particularly interested in either, beyond a general interest in learning new things.
That being said, I find abiogenesis a difficult pill to swallow. The general theory goes that, since most of the "building blocks" of life- amino acids, nucleotides, and saccharides- can arise through purely chemical processes, life itself could arise through a purely non-directed chemical process.
Let me make two opposing arguments here: the first is an argument by analogy to something I do know a bit about- computers. The second is a response to that argument.
Now, I have taken enough biology to know that life is CRAZY complicated. Much more complicated than the most complicated of computers. But lets imagine for a moment that you have a processor, and you have some non-directed chemical process spewing random bits onto a process's code segment. The processor happily trundles along, executing 32 bits at a time (yes... it's an x86 imaginary evolution processor) of this random data. Now a single 32 bit instruction can accomplish only a minuscule amount of work- you can add two numbers, multiply two numbers, shift some bits, load some data from memory, or jump to a new execution point. That's pretty much it. Everything your computer does is a wild, crazy, insanely cool combination of those operations (not unlike life, in fact).
To get anything meaningful to happen in a program, you need thousands- millions- of these instructions all chained together perfectly. If any one of them is off, you break the whole thing. Start over. So you need to get these millions of random bits in exactly the right order to get anything meaningful. The odds of a string of bits of length n randomly conforming to some predefined string of bits is equal to one in 2^n (roughly 10 ^ (n/3.32)). So the odds of getting a string of 1000 bits in a row exactly correct on the first try is about one in 10^(300). Number of atoms in the observable universe? About 10^80. It's hard to imagine how big of a number 10^300 is. Even if we had a billion chemical processes' spewing out a billion bits a second for each of the 4 trillion or so planets in each of the 125 billion or so galaxies in the known universe for every second in the last 13 billion years, we'd still have zero chance of getting the 1000 bits correct (10^30 * 10^30 * 4 * 10^40 * 125 * 10^30 * 60 * 60 * 24 * 365 * 13 * 10^30 = 2 * 10^171). In fact, mathematically speaking we'd have 0 chance of even seeing 600 bits correct (we'd expect to hit 568 bits once or twice)
And this is ignoring two HUGE problems. First, it takes a LOT more than 1000 bits to create life. Again, I'm no biologist, so I don't think I can speak for exactly how complex life is, but wikipedia tells me the largest human chromosome is 220 million base pairs long. If you're curious, that's 10^66,200,00 bits.
Second, it's not just creating life that we're talking about. It's creating self-sustaining, reproducing, evolution-capable life. If someone were to create a self-replicating, randomization-based evolutionary computer program that was able to not only survive, but evolve to the point of forming its own network cluster that was capable of rational thought and had a sense of self awareness on the scale of a human being, that would be the single biggest achievement of humanity. By a lot. Despite all our capability for design, all our effort, and all our ingenuity, we can't even come close to doing this. Not even close. Yeah, machine learning is cool, but compared to human reasoning? It's a joke.
Now, I think the abiogenesist has a good counter argument: what's all this talk about randomness? There's nothing random about this process. This is chemically driven. Chemicals react with each other in particular ways under particular conditions, such that it's totally conceivable that the right chemicals in the right proportions in the right conditions could create the cell structure necessary to facilitate life. Any "randomness" only comes into the picture when we ask whether or not that cell survives long enough to reproduce, and in what direction evolution takes that life. To use the computer analogy, anyone who's ever done fuzz testing knows that randomizing data inputs is almost never a successful attack vector. Instead, you take already existing ("good") data, and you tweak one or two bits to see what happens. If chemistry can get you the "good" data, and the environment can tweak a few bits, then all that math we talked about was for nothing.
The problem with the abiogenesist argument, of course, is that we haven't been able to find the right chemicals in the right proportions in the right conditions to replicate this. My understanding (again... not an expert) is that we've found some interesting reactions that look vaguely like they might be related to life formation, but we're not particularly close to replicating the correct conditions, or even verifying that it's possible to create all the base elements necessary, much less that they can combine in any meaningful way.
I'm not really sure how I feel about these arguments. I sort of like both arguments, actually. Let me put it this way: if abiogenesits are ever able to create life in a lab through purely chemical processes, I think it strikes a pretty big blow to religion. But they haven't yet. And they're not close. So what now? After all, they've only been at it for a hundred years or so, so are we really justified in saying they've failed, and we should turn to a religious answer? On the other hand, if the religious answer is true, then won't we forever be stuck in this "well, we just haven't figured it out YET..." paradigm? My inclination is that the totality of these arguments points towards life being unexplained by natural phenomenon- at least so far. While this seems to me a decently compelling argument for the supernatural, it does not, in my mind, have the strength necessary to convince me of the supernatural in a vacuum of other evidence.
3) Where did humans come from?
Two points to make here. First, humans are different from everything else in existence. We operate at a cognitive and self-aware level that no other life matches. And it's not just that we're different, but everything else is the same! All other animals are in the same ballpark in terms of instincts, intelligence, self awareness, etc. We're playing an entirely different sport.
The second point is that human civilization has a startlingly short history. Think about everything we've done in the last 5000 years or so. What exactly were we doing for the 50-200 thousand years before that? How is it that we managed basically no progress for the first 90+% of Homo Sapiens existence, but then have this explosion to the point of our modern understanding of the universe in the last tiny bit?
There seem to be two major theories here. The first says that there was some transformative event that caused humans to reach this level of behavioral modernity around 50,000 years ago. The second says there was no such event, and the transformation from beast to humanity was a gradual one, happening over the last 200,000 years.
The first theory seems to me a much better fit for what we observe. If the change was indeed a gradual one, I would expect our intellectual growth to be a gradual one as well. It hasn't been. The only thing slowing us down seems to be the base starting knowledge of the generation before us- not our intellectual capacity. Moreover, I would expect to see discernible differences in the intellectual and social capacity of different people groups that have been separated for the last several thousand years. We don't see this.
But if the first theory is correct, then what was the source of this change? A single genetic mutation seems to be the only explanation. But how crazy big of a change is that? That's not how mutations work- small changes accumulate over time, you don't have multiple significant changes all happening at once.
Incidentally, I see a way for Christianity to coexist here. What if the story of God "creating" Adam in the Old Testament is simply God making this transformative shift? I can see how God giving humanity the spark of life - the "soul", as it were- would be a form of creating humanity. This is the argument given by the Theistic Evolution crowd.
My ultimate conclusion to all this is that we simply don't know the answers one way or another. I find that a religious approach has answers to these questions- but it requires accepting something that seems at least as implausible as the natural explanations for these events, namely the existence of a deity. Atheism does, at least, provide some theories to explain our origins, but I find them unsatisfying. Moreover, there doesn't seem to be a consensus opinion among the experts about which of these theories is the most reasonable. As I said before, in my view a lack of a good answer here points to the fact that Atheism, as currently constructed, is missing something pretty important. However, that something may or may not be God.