## Wherefore Universe?

Today, as I sat around idly ruminating, a question which has often troubled me bubbled back up in my mind: why does the Universe exist? What is it about the laws of physics that somehow magically cause a Universe to come into being.

I’ve thought long and hard about this problem, and the other day, I believe that I may have hit upon a possible solution. Here goes.

We think of the Universe as a fairly orderly place. Even when we deal with really peculiar theories like the Standard Model and Quantum Mechanics, the Universe is orderly. Cause and effect always, always applies. Well, not quite. Imagine a cloud of gas floating in interstellar space. Now, imagine that you have some sort of super-microscope, and you zoom in on part of the cloud. Eventually, you can see the gas molecules, and then, the individual atoms. As you zoom in yet further, the nucleus of a single atom becomes visible, then the quarks and gluons that make up the interior of a single nucleon. Keep zooming in. It’s going to take a while, even at this rate. Your ultimate goal is to reach 10-35 meters, the so-called Planck length, which is 10-20 times the diameter of a single proton. This is it: the bottom of the Universe. There is no meaningful distance smaller than the Planck length. I know that seems nonsensical, but bear with me.

You see, to measure the position of anything, you have to bounce something off it, whether that be a photon, an electron, a proton, whatever. In order to determine the position with greater accuracy, you have to bounce the particle — let’s assume it’s a photon for our purposes — with a higher energy. The angle at which the photon returns to you allows you to determine the position of the target particle. Well, as it turns out, there is a theoretical limit to this precision. Once you know the particle’s location down to an error of less than 10-35 meters, such measurement requires so much energy that the measurement would produce a microscopic black hole, which would trap the bouncing photon, and prevent the information on the particle’s position from ever reaching you. So, it’s not meaningful to talk about any distance smaller than the Planck length, since nothing can interact with anything smaller than that.

The peculiarities at the Planck scale are legion. Not only can you not measure anything smaller, but space itself becomes unpredictable, twisting and warping and bubbling. Particles appear from nowhere and then swirl away into nothing. Energy is created and destroyed. And the important thing, causality does not seem to apply. Events can occur on the Planck scale without any cause in the Universe.

You might — if you were brave enough to actually read through that long, drawn-out description — be wondering what this has to do with the cause of the Universe. Well, I’m just getting to that.

You see, our current physical models of the Universe cannot actually tell us what happened before about 10-45 seconds prior to the beginning (that number, incidentally, is the Planck time. There is no meaningful time interval shorter than the Planck time, as there is no meaningful spatial interval shorter than the Planck length). That is because, before 10-45 seconds, the baby universe was smaller than the Planck length, which means that our traditional notions of space, time, and causality do not apply.

So, perhaps this is the answer to why the universe exists: there is no cause, or if there is, we cannot comprehend it, because causality is different or nonexistent at such tiny scales. Perhaps at such scales, where causality is so flexible, events can cause themselves. Or perhaps, even more paradoxically, effect can precede cause. So, perhaps, the origin of the Universe and the laws of physics were one and the same thing: the Universe itself.