I am currently reading the excellent book by Jim Holt – “Why Does the World Exist?”.

And it turns out that that question is related to one of my late night musings – “What is the simplest possible universe?”

As in every good debate, we start by defining our terms. “Something” is easy to define, at least as a bucket, but what is “nothing”?

One way to define nothing is to start with something and then take it away.

So we start with our universe and remove all the matter. Do we then have “nothing”? And is then the simplest possible universe “nothing”?

The problem is that emptying the universe is not as simple as subtracting 1 from 1 to give us 0.

Even if we removed all matter, particles would still bubble up from the Dirac Sea. The only way to stop that is to remove the fundamental laws of this universe.

But where are these? How are they manifested?

Are they intrinsic to our universe or do they sit outside? And if outside then how do they affect our universe and have we not just replaced God with an equally inaccessible controller?

If they are intrinsic then where are they? Wearing a Mysterian hat, perhaps they are in plain sight but are imperceivable to our consciousness.

Emptying the universe starts to seem a lot less simple.

In the book, Jim Holt gives three requirements for this subtractive model of nothingness. One of which he, though not I, thinks is a deal breaker.

For me the fundamental problem with the subtractive model, aside from the challenge mentioned above, is ghosts.

Ghosts do not exist, they are therefore nothing. But they are obviously not nothing as there is a word in the page “ghosts” and you who read it know what it means.

Ghosts are both being and nothingness. What do I take away from what to create the nothingness that is a ghost?