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A Profound Question

Entry 2103, on 2021-01-20 at 21:32:19 (Rating 1, Science)

What is the most important, momentous, and consequential piece of knowledge we can ever have? Here are a few candidates for that: what caused the Big Bang, what is the ultimate fate of the universe, is there a god, does objective moral good exist, do we have free will?

All of those are interesting, and topics I have covered in the past in this blog, but I want to offer another possibility, and it is one which is incredibly consequential whatever the actual answer might be. It is also a piece of knowledge which is less abstract than many of the others. And it should be of immediate practical importance to society as a whole.

OK, it's time to reveal the question. It is this: is there (intelligent) life elsewhere in the universe?

The question has existed for a long time and has been revived in popularity recently after various discoveries, such as: water on Mars; organic molecules in space and on planets and moons in our Solar System; mysterious objects visiting, specifically Oumuamua; and odd signals detected from space, such as the "Wow Signal" and mysterious radio transmissions from Proxima Centauri.

But even after discovering all of this, and decades of searching, we still don't know if intelligent life exists on other planets. In fact we don't know if life in any form exists elsewhere.

And that is deeply mysterious.

Why? Well, the universe is big, I mean really big. You may think it's a long way down to the chemist, but that's peanuts compared to space (sorry, but I just had to include that quote from the humorous science fiction book, "Hitchhiker's Guide to the Universe"). Because the universe is so big, and we have discovered a lot of planets orbiting other stars, it is fair to think there must be numerous planets where life might arise. But, so far, we have no evidence that life in any form exists on other planets.

When I say there are a lot of planets out there, I really do mean a lot. There are about as many stars in the universe as there are grains of sand on all the beaches on planet Earth. And we think most of those stars have planets orbiting them.

Consider that number. Go down to your nearest beach and pick up a handful of sand. Then try to count the grains. Now multiply that by the number of handfuls on that beach. Now multiply that by the number of beaches on Earth. It's a lot, isn't it?

Each of those sand grains corresponds to a star with multiple planets, and each of those planets might have the correct conditions to allow life to exist. Sure, there might be only one chance in a trillion that the conditions would be right, but that still leaves a lot of planets!

How many? Well, some estimates indicate there are 200 sextillion stars in the universe. Multiply this by 10, because stars probably have about 10 planets on average (don't even worry about moons at this point) and you get 2 000 000 000 000 000 000 000 000 places life might exist. Divide this by a trillion (because we are estimating only one in a trillion is suitable for life) and you still have 2 trillion planets with life. That's quite a lot!

Now let's consider time instead of space. The universe has existed for almost 14 billion years. Our Solar System originated about 4.5 billion years ago. Life got started within a billion years here, so we could assume the same might happen on other planets too. But many of the elements which life uses (carbon being the most obvious) were created in early stars and "recycled" in later stars, like our Sun, so life probably wouldn't be possible on planets orbiting the first generation of stars.

But that still leaves billions of years that life might have started on other planets before it started here. In that case we would expect advanced, intelligent life to exist as well. Yet we don't see any signs of this anywhere - this is the famous "Fermi Paradox".

So here's the point I want to make arising from the facts I have just presented: the universe is huge, and either intelligence exists on other planets or it doesn't. Either way, that is a deeply significant fact.

If there is no other life out there, and we are the only example in the whole universe, that is hugely relevant to how we should see ourselves philosophically. In that case life, and/or intelligence, must be unique to Earth. Surely this is an overwhelming reason to try to do our best. If we are the only intelligent life in the universe we sort of "owe it" to the universe to make the most of it, to overcome childish disagreements amongst groups, to try to understand reality as best we can, and maybe to colonise the universe (yeah, I know colonisation isn't seen as a positive thing at this point in history, but it really is a prerogative, in my opinion).

But if there is other intelligent life out there, then that is equally astonishing. There might be civilisations as advanced, or far more advanced, than ours. There might be species which can travel between the stars, who have a greatly more advanced understanding of reality than we do. Imagine what we could learn from these... if they weren't hostile!

So whatever the outcome of this question, the consequences are profound. The simple answer right now is that we just don't know. The fact that we haven't easily found signs of intelligent life already shows that either it doesn't exist at all, or something makes it far more rare than we might naively think, or that it is really well hidden for some reason.

Whatever the answer is, nothing is more important or consequential. We are developing better ways to study this problem, so I hope we might find an answer soon. But that has been a hope for many years now, so maybe it's just a lot harder than we think.

Comment 1 (6271) by OJB on 2021-01-21 at 16:40:49:

I just found this quote from Arthur C. Clarke, which sums up this post in a few words: "Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

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