Back to relativity again, so it was back to youtube.  Here are the videos I showed in class today.  We started with Ryan Chester’s award winning video on the Special Theory of Relativity.

I found these three TedEd animations a few weeks ago and they really helped me understand Lorentz transformations.

Einstein 100 – Theory of Relativity

And lastly, 2 Crash Course Astronomy videos on Cosmology

I didn’t show these in class, but they are also very good.

And finally here’s this website. You have to keep scrolling up ward to ‘animate’ it.

Its kind of hard to do a lab in my kitchen for general relativity so we worked on problems from the textbook, one of which involved the experiment done by Tom Van Baak.  Tom took his atomic clocks and his kids for a ride in his minivan to Mt Rainier for 2 days to record the effect of gravity.  When they got home they compared the clocks to the clocks that had stayed home and found a 20 ns difference.  We calculated if this was what was expected from general relativity and it was!   Tom Van Baak has a lot of information on his website, including a powerpoint presentation.

The other problem we worked on in class involved the two astronauts, Scott Kelly and Mikhail Kornienko, who just returned to earth last week after spending 340 days on the International Space Station.  We calculated the time dilation they experienced from traveling at 8000 m/s in the space station and the time dilation expected from being in a weaker gravitational field above the earth’s surface.  Since gravity is weaker the clocks will run faster, but moving at a greater speed means the clocks run slower than those on the earth’s surface.  We found that the astronauts came back to earth about 0.001 second younger than if they had stayed on earth!