How Many Things Are There?

Hey, Vsauce. Michael here. If you threw every single human alive today into the Grand Canyon, we would not fill it up. We could make a pile about this big. That's it. That's all of us. All 7.159 billion of us in one place. A species portrait. It kinda puts humanity into perspective and you.

So does this. Everyday you produce about one to two litres of spit, which means, in your entire lifetime altogether, you will not produce enough spit to fill an Olympic-size swimming pool. So far, 560 billion Lego parts have been manufactured and the total number of grains of sand on Earth is estimated to be 7.5 times 10 to the 18th. But here's the thing: how many things are there... total? Well, how do you define a thing? Well, let's say it's a thing if you can think about it or talk about it. If you can call it a thing, it's a thing. This is going to be a lot of things. Things can be real, imaginary, impossible, ideas are things, things can be looked forward to and things can be in the past or yellow or concrete or abstract things can happen and some thing's probably won't.

Making a video about how many things there are. That's a thing... that I'm doing right now. Let's count everything. Right away, the answer seems obvious. The word 'thing' is so vague, the answer is clearly infinite... possibly... not. All we have to do is take the maximum number of physical things, things out there in the real world, beyond our minds we could in theory measure and add to that the total number of things we could imagine. The total number of thoughts possible.

For the purposes of this video, let's assume that numbers and math and the laws of physics exist as part of the way our universe is. But the names and representations they've been given are the products of thinking minds and those things are, well, things that we can count. And there's no reason to double count. All of the indivisible pieces that make up me, particles or strings or whatever are the same as the thing that has been named me.

Abraham Lincoln has a great quote about this. "How many legs does a sheep have if you call its tail a leg?" Four. Because calling a tail a leg doesn't make it one. Okay, let's begin. When counting the number of physical things in the universe we hit an unknown. How big is the universe? The entire universe could be infinite or it could be finite, but edgeless for a variety of reasons. There could also be other universes. But it's unclear whether we'll ever be able to actually see all these things.

Instead, what we are stuck with, and what we usually mean when we say 'the universe', is the observable universe whose future visibility limit has been estimated to be only 62 billion light-years in any direction. That's it. This is likely the only inventoryable space we'll ever need to worry about. And it contains roughly, on average, ten to the eighty elementary particles. Particles with no further internal parts as far as we currently know.

So that's our answer, right? There are ten to the eighty physical things that exist out there, beyond our own minds. Any other physical thing - water, dogs, planets, saxophones - are just names given to particular arrangements of those same ten to the eighty particles. But wait, what if, in the future, we discover that what we call elementary particles today are actually just made out of smaller things we should have counted instead? Well, to cover ourselves let's count the maximum possible number of the smallest measurable thing.

Something the size of a Planck volume. 10 to the power of 183 things that small could fit within our observable universe. I like this number, 10 to the power of 183. You couldn't easily argue there were more things than that in the physical, real-world. But you could imagine. A Planck length, a Planck volume. That's just the smallest measurable amount of space, not the smallest possible. You could imagine a half Planck volume, a 10,000th of a Planck volume. But, that would just be a thought and only ever a thought.

So, how many possible thoughts are there? It's probably safe to say that the number of possible thoughts is, indeed, infinite. For example, numbers. You can't say there's a limit to the biggest number we can imagine. But, unlike physical things that exist whether or not we have discovered them, do unthought thoughts already exist? It seems more like the pool of possible thoughts is really just one thing; an actual elements from that set don't become things by themselves until we think them, that is, we or some other mind thinks about them or talks about them and there's a limit to how many things we or anything else could ever think.

Our observable universe is only so big and it will contain usable energy for only so long. After about 1 trillion to a hundred trillion years the supply of gas needed to form new stars will be exhausted and the lights will start going out one-star at a time. After a Google years the amount of usable energy left in the universe will be 0 and nothing will be able to happen.

To calculate the maximum number of thoughts that could be thought inside our observable universe, let's take all of its mass and turn it into human brains that just think new and random thoughts from the beginning of time until the universe runs out of usable energy: a Google years of thinking. But wait, what if there are alien brains or for all we know Earthling brains that think faster than we can? Okay, well to be safe let's not turn all of that mass into human brains; let's use it to build a giant hypothetical machine that computes at the fastest speed possible given the speed of light in the uncertainty principle; Bremermann's Limit.

It's 1.36 times ten to the fifty bits per second per kilogram of material. Now a high-end estimate for the total mass of the observable universe is 3.4 times ten to the 60 kilograms which used exclusively for the best possible computing machine could altogether process 4.624 times ten to the 110 bits per second. Now with 3.154 times 10 to the 116 seconds available from the beginning of time to the heat death of the universe and an assumption that the average thought takes about a sentence worth of information to describe, say about 800 bits, we get a total of 1.458 times ten to the 227 things that could ever be thought or imagined.

That number is huge. In the observable universe, the universe as we will ever know it, the number of thoughts that can be thought is so much larger than the number of physical things there can be without imagination and if you were to combine the two totals, the number of physical things would barely make a difference. So, funny enough when it comes to everything in the universe, it really is the thought that counts. And as always, thanks for watching.