Built on Facts

Archives for March, 2009

Correlation v. Causation

Via xkcd, an unusually clever comic even by the standards of this unusually clever comic: It goes right to the heart of one of the greatest philosophical difficulties of science. All we can do is measure correlation. We can never be assured that we’re not just getting lucky and that in fact the fundamental-seeming physical…

Counting Photons

ScienceBlogs’ own Chad Orzel has on a number of occasions discussed the photon concept in relation to physics pedagogy. He thinks (as I do) that it’s a good concept to teach early even though formally speaking photons are considerably more complicated than the “particle of light” idea that’s often presented as an intuitive concept. But…

The Amazing Spider-Man!

Spider-Man, of mass 90kg, is perching 10 meters above the ground when he notices his (depending on the continuity) crush/girlfriend/wife Mary Jane (50 kg) being menaced by… I dunno, a menace. I’m more of a DC fan really. He swings down toward her to spirit her our of harm’s way. Assuming he starts from rest…

Stocks and Efficient Markets

It occurs to me that I still haven’t scored and posted the winners of the BoF 2008 Election Prediction Contest. Formally I still can’t, because the Minnesota senate race has not legally been resolved. For all practical purposes it has, but I like to be sure about things before I go and award the contest…

Going Deeper

In high school and introductory college chemistry you’re going to do a lot of problems involving the ideal gas law. It runs something like this: PV = nRT So simple I don’t even have to typeset it. Pressure times volume equals the number of moles (n) times a particular ideal gas constant (R) times the…

Sunday Function

A tricky one: At x = 2, f(x) = 1 + 2 + 4 + 8 + … Which, uh, is clearly not going to end anywhere finite. The series fails the single most basic necessary (but not sufficient) condition for convergence of infinite sums – that the terms of the series approach zero as…