In one of the Science of the Discworld books (I'm too lazy to go check) the authors joke that it is required by the union of science writers that they mention Schroedinger's cat and the twin who flies off on a rocket ship and comes back to find his twin back home all aged and decrepit.
In another book on physics (again, I'm too lazy to get the reference unless someone asks for it), the author has exhausted all sorts of thought experiments and goes on to say that there is "a real example": the aged twin.
In what sense, I want to ask the guy, is that "real"? It has never happened that someone has traveled off at the speed of light and come back all rested-looking. I have always found it very irritating that physicists can take something completely imaginary like this and think of it as observable data.
I was therefore really happy to read about the muons. I had not heard of this experiment before, and -- since I've always accepted relativity on faith -- I'm really happy that technology has advanced to the point at which it is possible to have measurable, observable confirmation of the theory.
I'm still sort of irritated by Figure 2, though. I read this chapter while giving an exam and found that on the way home everything I looked at had arrows and little letters on it. Do you know what I mean? You look at a building and there's the hypoteneuse of the triangle formed by the wall and the ground, in imaginary dotted lines. I figure this must happen to other people sometimes, not just to me, because I see it in movies sometimes.
But Figure 2 means nothing to me at all.
So this was my favorite part of chapter 3 -- the opportunity to get rid of the Aged Twin.
What was your favorite part?
Subscribe to:
Post Comments (Atom)
Figure 2 threw me off a bit at first too (they could have thrown in a few more labels). It helped me to visualize the light clock with one mirror on top and one mirror on the bottom rather than side by side. As long as the mirrors are parallel to the direction of movement of the train, it shouldnt matter though. The two solid lines in the middle of the figure make up the path of light. The first half-tick starts at the bottom mirror. If the train were standing still, the next frame would have the path of light going straight up 1 meter. Since the train is moving, however, (remember this is from the perspective of the person standing on the platform) light has traveled both up 1 meter and forward by a bit too (vT). The same goes for the next half-tick when light travels back down to the bottom mirror.
ReplyDeleteDoes that help or make it worse?
The description worked for me, actually, so I shouldn't have complained about the illustration. I'm just not a very visual person.
ReplyDeleteCouldn't they have drawn a picture of the clock?
However, your point about the forward movement definitely helps. I can see what they were getting at now.