Luke_A_Somers comments on Can infinite quantities exist? A philosophical approach - Less Wrong

-9 Post author: metaphysicist 03 January 2013 10:52PM

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

Comments (28)

You are viewing a single comment's thread.

Comment author: Luke_A_Somers 03 January 2013 10:05:01PM -1 points [-]

It's not clear to me that MWI has infinite worlds rather than merely 'a mindbogglingly huge number, so large one may reasonably approximate it as infinite for most purposes'.

Comment author: SilasBarta 03 January 2013 10:19:39PM *  3 points [-]

Worlds aren't fundamental in MWI; they don't show up the equations. It's just a loose, non-technical term you can apply to a subset of the wavefunction. But under most common definitions of a "world", there are "uncountably many" in the same sense that there are "uncountably many" (sub-) line segments within a given line segment.

Comment author: Luke_A_Somers 03 January 2013 11:12:41PM *  2 points [-]

I'm aware of that. I mean that there are fewer effectively different worlds than that. Like, if you consider a scattering event - a major source of decoherence and thus new world formation.

With which other particle will this particle's next interaction (over some minimal threshold of impulse) occur, cut off by time X in some reference frame (e.g. our frame, right now)? (setting aside the fact that particles don't have individual identities, since that would decrease the world count)

This is a stronger question than that asked by decoherence, but you can already see we've narrowed it down to something that seems like picking out of a list - even if the universe is infinite, the number of particles in a truncated future light cone is finite.

Of course you're doing this a huge number of times, and each one creates a huge number of alternatives, but that's just making an unimaginably huge finite number. See?