Why does anything exist?

Part of the Hubble Ultra Deep Field.

Why is there a universe? Why are there atoms, people, planets, and 2 trillion galaxies?¹ Why does existence exist? This is one of those questions we used to put to philosophers and nowadays tend to put to scientists instead.

Existence does exist. So there seem to be two possibilities. Either existence has always existed (so far) or there used to be a time when it didn’t.

1. Existence didn’t always exist

To start with the latter: if existence did not always exist, there must once have been nothing.

Since at least the ancient Greeks, philosophy (and science, insofar as the two were indistinguishable until two or three centuries ago) has often been sceptical of existence coming into being ex nihilo (Latin for ‘out of nothing’). It was Parmenides who first argued that ‘nothing comes from nothing’ (usually presented in Latin: ex nihilo nihil fit).

The alternative was to present it in the religious terms of creatio ex nihilo or ‘creation out of nothing’. The Abrahamic tradition ascribes existence to a creator God. Ancient Near Eastern and Classical mythology said the gods created the world out of already-existing primeval materials, which sidesteps the issue. Either way, the supernatural is merely a placeholder for ignorance. The next question of course is, why does God exist? What created Him – or, since gendering an absolute being seems foolish, It? The appeal to divinity merely puts the problem back one step. The ancient Israelites who wrote the Old Testament resorted to a fairy tale because they lacked better ways of accounting for the world.

Modern science offers a theory of how the universe could start ‘from nothing’ called quantum fluctuation.² On this theory, tiny bubbles of space-time can spontaneously pop into existence in a vacuum because space has uneven density and is therefore unstable. However:

A vacuum is not nothing.

• A classical vacuum is completely empty space. But space – even empty space – is not nothing. Things can pass through it and it can be measured. And in fact, interstellar vacuum (a more perfect vacuum than we can create on Earth) contains bits of gas and dust known as the interstellar medium. 
• A quantum vacuum, i.e. the quantum state with the lowest possible energy, is also not nothing, as it contains the fluctuations: electromagnetic waves and particles that pop into existence. 

If quantum laws apply, then it’s not nothing. The presence of quantum laws is something, which has to be accounted for. Where did the quantum laws come from? The ‘laws’ of physics cannot exist separately from the material universe that they apply to.

In short, quantum fluctuation still has to presume that something exists, and therefore the cosmologist’s conception of ‘nothing’ (empty space) is different to the philosophical one (a state of non-existence or non-being). Of course, we struggle to think in the latter terms. As soon as we start to ask if nothing can exist we are caught in a linguistic muddle.

We cannot assume that such a state is possible. Even zero is a number. And how do we think of a time before existence in which, by definition, there was no ‘time’? ‘Nothing’ may be no more than an abstract intellectual construct, impossible for spatial-temporal beings like ourselves to properly conceive, and impossible in practice.

2. Existence has always existed

That leaves us with the other possibility – that existence has always existed, in one form or another. We can’t rule out the possibility that at some point it will stop existing, but that raises the same problem of time: how can there meaningfully be a ‘time’ when existence ceases? And where would all the stuff go? It seems the best thing is to conclude that there has to be something, and that it is eternal.

The Big Bang theory contends, on the basis of a vast amount of evidence, that our universe burst into existence 13.8 billion years ago. If it had a beginning, the universe – at least in its current form – is not eternal: something must have existed before it. We may never know what, but we have to assume there was something.

Without a creator God or gods, the idea of purpose is redundant, as purpose requires a will. Instead we can look only for causes. We humans find it hard to conceive of things not having a cause. Yet any appeal to causes leaves us in an infinite regress:

What caused the Universe? The Big Bang.
What caused the Big Bang? Whatever condition existed prior to it.
What caused that condition? And so on.

Conclusion

Why does anything exist? We don’t know, and it is hard to give a coherent answer. The question is so far out of our comprehension that we can only speculate, and most of us have better things to do. We must simply take it as a given, a brute fact, that existence exists. As theoretical physicist Sean Carroll has put it, “there is a quantum state that evolves through time according to the laws of physics, and that’s all there ever was.”

Notes

1. SciShow Space have a nice video about the number of galaxies here: https://www.youtube.com/watch?v=KOURqm-MB4s
2. See for example Lawrence M. Krauss, A Universe From Nothing (2012).