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Showing posts with the label the continuum

Zeno for the computer age

If you wish to better understand Zeno's worry about the continuum, you could do worse than to consider loops in software. Case 1: You want to loop over 10 records. You write: for i from 1 to 10     process_record() What could be simpler? OK, let's loop over the positive integers, finding the prime numbers: for i from 1 to ∞     check_for_primality() This loop will run forever, but it is a perfectly valid loop. We can even set it up to loop over all integers: j = 0 for i from 0 to ∞     j = j - 1     print i     print j And with only a little more trouble, we could loop over the rational numbers as well. But what if I ask you to loop over the real numbers between, say, 0 and 1? The problem here is much worse than the loop running forever: the loop can't even get started. We could print out "0"... and then what? There is no "next" real number to which we can proceed. And note: the concept of a lim...

Zero Percent Chance, Part Two

Surprisingly, my post on probability theory has generated quite a discussion thread. (And here I thought I saying Ron Paul won't win the GOP nomination was the key to lengthy threads!) In the course of the discussion, I thought of a way to refine my first example to clarify the issues a bit. Instead of an infinitely fine-pointed dart, let's take an ordinary one, and instead of the real number line, we'll just throw it at the wall. Now, I ask you, "Does the exact middle of the head of the dart have some exact x, y coordinates on the grid of that wall, despite the fact that, of course, we could never measure that exact x or that exact y?" If you answer "yes," then I will note that there was a 0% chance that the dart would land at those coordinates, and yet there it is. If you answer "no," you have adopted a respectable philosophical position, denying the physical reality of the continuum. But you have changed subjects on us: you've do...