How Long Would It Take to Fall Through the Earth?

There is a new paper on estimating how long it would take to fall through the Earth that does better than the standard crude approximation. I think this is very cool, and I definitely suggest taking a look at the other side of the link.

And I am again reminded that I should have found a way to take the course "Order of Magnitude Physics" at Caltech when I had a chance. (But, thankfully, I often get to think that way for my research.) I just did some googling, and I found the material from the 1995 and 1997 versions of the class.

But I still have one question: How can I make sure that I take the correct turn at Albuquerque?

(Tip of the cap to Physics Today for their post on Facebook.)

Jose Canseco's Theory of Gravity

Jose Canseco promised his thoughts on gravity and then he delivered his theory of gravity in a sequence of Twitter posts.

Wow. Why didn't I think of that explanation?

Comedy Gold.

(Tip of the cap to Rob Neyer.)