wnoise comments on The Absolute Self-Selection Assumption - Less Wrong

16 Post author: paulfchristiano 11 April 2011 03:25PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (38)

You are viewing a single comment's thread. Show more comments above.

Comment author: wnoise 12 April 2011 12:59:01AM *  1 point [-]

Observing a Geiger counter near a piece of radioactive material was one of the highlights of my undergraduate physics labs. And the time distribution of clicks is random in the same sense that the OP was using.

Comment author: Sniffnoy 12 April 2011 01:58:27AM 2 points [-]

I think the bigger problem is not randomness vs. pseudorandomness, but rather the question of whether uncountable probability spaces actually exist in physical situations.

Comment author: wnoise 12 April 2011 05:00:10AM 1 point [-]

I believe they do for the same reasons I take seriously the existence of other Everett branches. In fact the mapping is rather straightforward: I can't observe or directly interact with them in full generality, but the laws governing them and what I can observe are so very much simpler than laws that excise the unobservable ones. Whether I can actually exhibit most real numbers is besides the point.

Comment author: Cyan 12 April 2011 05:11:24AM 0 points [-]

Is there a demonstration that a physics based on the computables is more complex than a physics based on the reals?

Comment author: JoshuaZ 12 April 2011 05:51:41AM 4 points [-]

Is there a demonstration that a physics based on the computables is more complex than a physics based on the reals?

This is a complicated question. In practice, it is difficult in this particular context to measure what we mean by more or less complicated. A Blum-Shub-Smale machine which is essentially the equivalent of a Turing machine but for real numbers can do anything a regular Turing machine can do. This would suggest that physics based on the real is in general capable of doing more. But in terms of describing rules, it seems that physics based on the reals is simpler. For example, trying to talk about points in space is a lot easier when one can have any real coordinate rather than any computable coordinate. If one wants to prove something about some sort of space that only has computable coordinates the easiest thing is generally to embed it in the corresponding real manifold or the like.

Comment author: Cyan 12 April 2011 03:29:05AM *  0 points [-]

As Sniffnoy notes, the bigger problem is about the observation of an actual real number. Any observable signal specifying the instant at which the particle triggered the counter has finite information content, unlike a true real number. This includes the signal sent by your ears to your brain.

I shouldn't have mentioned pseudo-random number generation in the grandparent -- it's a red herring.