This question has been bugging humanity since forever. “Why is there something rather than nothing?”. It’s usually thought that we have no answer. But I think modern physics actually answers this question. This post will explain how.
It’s all down to two insights from modern physics.
I think a large part of the force behind the question is due to our intuitions about grounding. We think “Why is this car here?”, “Well, because the driver drove it here”. One fact is grounded in another. The present is grounded in the past, which is grounded in a deeper past, and so on. So for every existing thing, there is always some thing that grounds its existence, some foundation on which its existence lies.
But the Theory of Relativity showed us that reality just doesn’t work that way. What exists is all of spacetime, an entire four-dimensional structure. Rather than a three dimensional space that’s evolving in time, with one part being caused by the parts prior to it, we have a strangely-structured reality where past, present, and future all exist equally, all of them are parts of the four-dimensional spacetime which alone exists. The me that’s writing this right now, the me that was a year in the past, the me that will (I hope) be a year from now – all of them exist to the same extent, all of them are part of the atemporal reality.
And hence, none of them “grounds” the other. The equations of general relativity describe the structure of this four-dimensional spacetime, but in it the past does not determine the future any more than the future determines the past (or the right determines the left); indeed, the equations are symmetric in all four dimensions (the distribution of matter violates this symmetry, but let’s not get into that). Four-dimensional spacetime has a structure, described by Einstein’s equations, but no part of it grounds some other part. It all just exists, as it is, atemporally.
So there is no grounding for reality. Reality just exists, as it is. Indeed, no grounds for it is possible, for to ground something we need to have some independent, separate, thing which exists to act as the ground; and nothing exists outside of reality, nothing that can ground it. Thus, the whole idea of seeking to ground reality is wrong-headed.
That still doesn’t answer the question – granted that there is no “ground” to why reality is the way it is, we’d still want to understand why is there something rather than nothing. Here I think it helps to broaden the question. Instead of wondering why there is something rather than nothing, let us consider why is there this reality, rather than another.
Things could, supposedly, have been otherwise. From tiny changes like my name being different, to huge ones like finding ourselves living in Paradise, surrounded by angels. Infinite possibilities. But it seems that only one possibility, out of this entire infinity, got chosen. Why only one? Why this one? Why not some other one – like, say, that there would have been nothing?
Here the other great theory of modern physics offers an interesting insight. Quantum mechanics strongly indicates that it’s just not true that only one possibility got chosen. Instead, all possibilities got chosen, all possibilities exist equally.
Consider throwing a tennis ball at a wall which has an open window in it. Our experience tells us that there are two options here – either the ball will bounce off the wall, or it will pass through the window. When we throw the ball, only one option out of these possibilities will occur.
Quantum mechanics tells us that this intuition is wrong. It’s an illusion caused by statistics – we see things work out this way because the ball is made up of lots and lots of tiny particles. If we’ll throw tiny particles at the wall, something else happens. If we throw, say, an electron at the wall, reality splits. In certain parts of reality – in some worlds, so-to-speak – the electron bounced off the wall, and in other parts of reality – in other worlds – the electron passed through the window. Both possibilities are part of reality, they equally happen. Quantum mechanics tells us that all possibilities are actualities, that reality doesn’t contain just one possibility but rather it contains all of them. Reality is a plenum.
Now at this point I should caution the reader that the above is only one interpretation of what quantum mechanics tells us about the world. I think it’s the correct one, and we can leave the reasons why for another post. The important idea here is that this option opens up a new way to look at the question we’re dealing with.
The idea that reality is a plenum answers the question. “Why is there something rather than nothing?” “Well, it’s because it’s not. All possible realities exist, including the one where there is nothing. It’s just that we, being something, naturally find ourselves in the possibility that contains something, rather than in that which contains nothing”.
But more than that, the idea of the plenum changes the question. The question now becomes “Well, why is there a plenum? Why do all possibilities exist, rather than only some possibilities, or only one – say, that there is ‘nothing’?”
Notice, however, how the tables have turned. In the original formulation, “Nothing” appeared more plausible. We asked why Something exists rather than Nothing because it seemed to us that Nothing would be simpler than Something, that it would be easier to understand why Nothing exists. Now, however, things are the other way around. The idea that all possibilities exist is simpler than the idea that only some – say, the odd realities, in we were to count them – exist. It’s easier to accept that all possibilities exist than that some arbitrary parts of this structure-of-possibilities exist.
It’s now apparent why there is something, rather than nothing – it is because all possibilities exist, because reality consists of all possible realities, including the possibility that there is ‘nothing’. They all exist atemporally and without any outside “ground”, as what exists is not grounded in anything else. And this all structure is much more plausible than the hypothesis that only one of these realities – say, the one that has Nothing – exists, as there is no reason to think reality is bounded in this way.
This answer is fine as far as it goes, but I think there are still two big problems with it.
First, the force of this argument is rather weak. It’s enough to sway the pendulum to the other side, to make use realize that a reality which is a plenum is actually more plausible than one which contains only a single possibility – but it’s not enough to make us see why reality needs to be this way, why it has to be the full plenum rather than a single possibility.
Secondly – we still don’t have very good evidence that all possibilities are manifest. What quantum mechanics actually says is that all of the possibilities within the laws of physics exist equally. Cosmological models and speculative physics like string theory extend these laws, maintaining that the laws in our universe are but a single possibility within a larger multiversee which answers to broader laws; but even in these theories, reality still conforms only to certain physical laws, rather than truly containing all possibilities. The only serious attempt I am familiar with to claim that reality indeed contains all possibilities is the so-called “Mathematical Universe” theory proposed by quantum cosmologist Max Tegmark. But this is still a wild conjecture, that lacks any considerable justification. We just don’t have good evidence, yet, that reality is a fully plenum, containing all possibilities – although this idea is indeed gaining popularity and plausibility as our knowledge of physics progresses.
This, then, is my answer to this Big Question: it seems plausible that reality is the way it is because it is every way – but we still don’t have the evidence to say this with any degree of certainty.