The Long View

Sometimes, when thinking about the track that humanity seems to be on right now, it's fun and interesting to think about the long-run view of it all.

There are a few different scales to consider. Let's go backwards.

First, in the cosmic sense, nothing is destined to last. While cosmologists aren't really sure what the universe, as a whole, is doing, they know it's one of several options. So here's what we know: at one point in the distant past, the universe (an infinitely dense speck of matter) started expanding. Exactly what the universe was before a tiny dot is unknown - we'll get to that. But this entire notion of expansion is pretty key, because the truth is that we can't even really talk about the universe being a tiny dot. There was nothing else to compare it to. This isn't even as philosophical as it sounds - there just wasn't anything else (there still isn't). There wasn't nothing that the tiny dot expanded into, there was just what there was, if that makes any sense.

So the universe started expanding very quickly. And as it did, it went from being very hot (like, so hot atoms couldn't even form) to something cold enough that proper elements like hydrogen could get together - but still hot enough for a bit of fusion, from hydrogen into helium. But it kept expanding, and eventually we got stars and planets and such. And now we're at now.

But the universe is still expanding. And weirdly enough, that expansion is speeding up. Again, it's not that all the galaxies are starting to move faster - the actual space in everything and between everything is just getting larger, like a balloon inflating.

So, three options. First, expansion could continue (and continue speeding up) and we end up with a universe where all the heat and energy is so spread out that it amounts to basically nothing. If there is matter left, it's just dark rocks, hurtling through space. This is called heat death - because there's nothing left but cold.

Second, expansion could slow down, then stop, then reverse. It would be mighty strange, but eventually, everything would wind up smashing back into a single, tiny point - like the universe at the beginning of time. At the end of time, time itself would essentially cease. Maybe something we don't know about would cause it to blow up again, and then a new universe would start up - who knows? It'd be a nice cyclical kind of thing, though.

Third, we could just end up bouncing back and forth, as expansion proceeds, reverses, stops before the Big Crush (as the second option is known), then starts expanding again. In terms of long-term, this is probably the best option for us to hope for, because the universe won't really end, and the expanding and contracting would probably stir things up enough to prevent heat death (maybe). So that's cool.

But any way you look it, it'd be a difficult universe for humanity to survive in forever. We probably won't manage.

After all, if we go down a scale - down from the universe to the much, much smaller solar system - then prospects are much more immediately bleak. In about 6 billion years (give or take a couple billion) the sun will turn into a red giant. Basically, the sun will fuse hydrogen in its core until there's no more - all that's left is helium. At that point, the sun will collapse a little - enough to start burning a bunch of the hydrogen outside of the core - and the outer shells of the sun will puff way out, and the sun will grow until its outer limits are at about Mars. The astute observer will notice that the Earth is closer to the sun than Mars. Well, so.

If we're still around when this happens, one hopes that we will have found a way to avoid this fate. But in any case, the Earth itself will be doomed (unless we do something really drastic like move the planet, which seems a little unfeasible. Maybe by then we'll be wise enough to let go.

So in terms of human events on the planet Earth, the sun going red giant is probably our upper limit.

But stepping down in scale again - to the level of our species - will we even be around that long to notice?

Generally speaking, species don't last for that long. It's hard to say how long an average species lasts - almost as hard as saying exactly what distinguishes any particular species. What we do know is that in the natural order of things, species go extinct and are replaced by new ones all the time.

The words "natural order" is key, though. As we can see from our current situation, there are a lot of natural rules that don't really seem to apply to humanity. In general, we're a strange one anyway - homo sapien is curiously lacking in close relatives (aside from big foot). For some reason or another, we are quite alone in our particular niche.

Also of importance is that our particular niche seems to be snubbing the natural order every way we can. We create simple ecosystems through agriculture for the sole purpose of supporting ourselves. This is a good thing - it's led us to be pretty successful, all around, in terms of ensuring our own survival. Agriculture and other technological advances have essentially led us to snub all the traditional carrying capacities that tend to limit the growth of a species. By and large, we have (or have the capability to) prevent the sorts of famines, diseases, competition, and over-harvesting that normally limit the size of a population. And the environmental, harmony-with-nature perspective of this blog aside, that's a pretty cool thing. I certainly don't want to change that.

The question becomes whether we have an unlimited ability to step over natural hurdles. We have vaccines and antibiotics, for example, that prevent population-controlling events like diseases, for example - but a highly resistant super-epidemic could still come into existence. And while we're really good at producing food, there could very well be an upper limit on that, too. So not to be all doomsday-scary, but who knows if we can keep snubbing the natural order.

So what's that mean? Does it mean that the day may come where humanity recognizes that it's time for its natural extinction, and goes quietly in the night? Well, probably not. But it may mean that we'll have to start limiting ourselves.

Of course, as a species, we've also discovered space flight (in all of its impracticality). We're not exactly close to getting any sort of significant number of people off the ground, or sustaining them once they do, but someday that may be the best answer we have. I hate the idea of condemning long-term ideas by labeling them sci-fi, but let's be honest - space colonization pretty much is. And that's okay.

But I could go around in circles on this for ages. Let's step down another step, to the sort of future we can imagine - say, 10,000 years.

Here's the state of things. The climate is changing. Research suggests that if we don't start working to prevent it, a bunch of feedback cycles will kick in and push us into a truly warm age. This'll be bad in the short term - the next 1,000 years, which is how long the effects of climate change will stay with us once it really gets going. The climate is a really big system - took us 200 years with all of our technology to really get it moving, and it'll take a long time to shift back.

But even if that happens, humanity will survive. We are survivors. After all the catastrophe is done, the climate may very well settle down into something nice, and we'll be ready. In the medium run (again, 10,000 years - ish) it might actually be a good thing. Or, biodiversity will be so utterly wrecked by human expansion and climate shift that nature, all over the planet, will start failing. That would be bad (and seems a little more likely - most of nature isn't equipped to react as quickly as we can).

I don't know whether that's meant to be hopeful or not. I certainly don't find it especially comforting. But after shirking all of nature's hurdles and built-in controls, maybe we've hit one we can't fix. It's a basic, discomforting truth that we don't even know if achieving 450 by 2050 will actually help anything. We hope it will - and suspect it will - but we don't really know. And this isn't even the standard models-don't-work denier stuff; we just don't have a very good idea of how far we'll get ourselves into feedback loops with a concentration of 450 parts per million, and it depends on a lot of factors.

But we'll survive. Whether or not we'll end up with a world we'll enjoy, take comfort in, and be able to thrive in - that's another question entirely.

On the other hand, though, the Earth is pretty screwed in half a dozen billion years anyway. Why try, right?

Incidentally, there's a lot of beauty in the idea that the universe will someday collapse back into a new Big Bang, isn't there? I hope that's the one that happens. And hey, maybe someday humanity will be widespread and powerful enough to make it happen.