Problem 255 Relativistic Doppler Shift

Added: 2026-05-12

[00:00:02]Hello, hello, hello. Today  is Saturday, May 9, 2026.

[00:00:13]Problem 255.

[00:00:19]A star is moving with a speed of 0.3 times the  speed of light 0.3C relative to us.

[00:00:35]The angle at which the star is  moving relative to us is alpha.

[00:00:45]What are the angles for alpha at which  there is no red shift and no blue shift?

[00:00:56]Uh classic problem.

[00:01:01]Would I have been able to do this in high  school? Probably not. But many of you, I'm sure, will be able to do this problem.

[00:01:14]All right.

[00:01:18]Problem 256 will be super special.

[00:01:28]It is related to an interview that I had in 2012 and that interview lasted 1 hour and 51 minutes.

[00:01:46]If you go to my playlist boost  to my playlist interviews, it is the very first interview on that playlist.

[00:02:03]You may benefit from spending the  time already now to watch the entire 1 hour and 51 minutes because that will  greatly help you to solve the problem 256 but it's very time conssuming I agree to  watch 1 hour and 51 minutes. But it is for you interest to really start doing  that. But this is problem 255 which is completely different. Of course, a star  is moving with a speed of.3 the speed of light relative to us. The angle at which  the star is moving relative to us is alpha.

[00:03:02]What are the angles for alpha at which there  is no red shift and no blue shift? All right, I wish you all the best. It's now  Saturday. Your weekend may all be over.

[00:03:25]If you cannot do this problem, don't feel  bad. I discover in principle this problem uh in my lectures, not in a direct  way, but basically the same idea.

[00:03:47]All right, then.

[00:03:51]I'm looking forward to your  solutions and if you can't do it, we'll be friends anyhow. Red is always a given.