No doubt anyone who’s reading this already knows about the web comic xkcd. (If not, drop what you’re doing and start reading it.) But you may not know that the author, Randall Munroe, has started a new feature in which he answers a weekly “what if” question about physics (broadly construed). There have been three entries so far:
- What would happen if you tried to hit a baseball pitched at 90% of the speed of light?
- What if everyone who took the SAT guessed on every multiple-choice question? How many perfect scores would there be?
- How much Force power can Yoda output?
I actually don’t think his answer to the first one is quite right. He says there’d be a lot of nuclear fusion reactions, but I don’t see any reason to think there would be. The collisions are certainly energetic enough for fusion to happen, but I think the probabilities (cross sections) for other reactions, mostly simple scattering, are much higher than for fusion. At first I thought that this made a big qualitative difference in the expected behavior, but I don’t actually think it does: the ball’s kinetic energy is so large that the extra energy released via fusion wouldn’t make much difference anyway.
Anyway, that’s a quibble. The main point is to entertain (while conveying some scientific information), and as you’d expect Munroe is awesome at that. A little excerpt:
Next, we need to know how fast it was rising. I went over footage of the scene and timed the X-Wing’s rate of ascent as it was emerging from the water.
The front landing strut rises out of the water in about three and a half seconds, and I estimated the strut to be 1.4 meters long (based on a scene in A New Hope where a crew member squeezes past it), which tells us the X-Wing was rising at 0.39 m/s.
Lastly, we need to know the strength of gravity on Dagobah. Here, I figure I’m stuck, because while sci-fi fans are obsessive, it’s not like there’s gonna be a catalog of minor geophysical characteristics for every planet visited in Star Wars. Right?
Nope. I’ve underestimated the fandom. Wookieepeedia has just such a catalog, and informs us that the surface gravity on Dagobah is 0.9g.