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Comment by bmitc | Hacker News Reader

I don't think the current models suggest the universe is infinite. As far as I understand, there is a finite amount of atoms supposed.

Also, there are very clear examples of physical limits to growth. For example, gravity and its interaction with the other forces prevents animals, buildings, trees, stars, etc. from growing too big. What happens if they grow too big? Collapse.

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Which model? They are diverging you know.

The observable universe is finite, is it not?

A finite observer would observe a finite universe.

Long story short your ability to observe qualia suggests to you that you have a faculty which is infinite.

Why? That's not how most models of practical computing work. If you don't need infinite precision you can do with a lot less and break loops/recursions.

If quantum works infinite precision is free.

I'm not sure if that's true in practice, but even if so, how's that an argument for an infinite universe?

You need an infinite universe to have infinite precision. The existence of transcendental numbers such as pi seem to indicate this is the case.

That just means that you can't realize infinite precision, infinite length, or infinite time. That's fine, and is probably correct. Good and Real by Gary L. Drescher (2006) talks about it, but large parts of the book are "wrong" (in the same way Occam's razor is wrong, not the same way the flat Earth is wrong). I'd say almost all of it is fixable though, so it's useful. I'd look out for the parts on the multiple worlds hypothesis of quantum mechanics (no better than modern version of the Copenhagen interpretation, unless you think wave function collapse is a physical event that has a cause), gives more respect to Wolfram's cellular automata ideas than it should (it should give almost no respect at all), and accepts evidential decision theory more than it should. Sabine Hossenfelder and modern causal decision theorists would have problems with it, but it's a good introduction for people who think human brains are magical and/or better than computers.

The observable universe is finite for the simple reason that its age is finite and the speed of causality (light speed) is finite. However, the observable universe is an artificial partitioning based on our specific (and arbitrary) location in space-time. It doesn’t have an implication on the universe as a whole.

Of course, in the context of this thread, the fact that only a finite subset of the universe is accessible to us is very relevant.

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