Space Travel, Einstein, and GPS

Below you'll find the slides from my Physics Day presentations at Space Center Houston, embedded via SlideShare. I was doing the TED-style minimal text thing, so they're probably not all that comprehensible on their own.

The event was supposed to have a pop-culture connection, so I decided to use space travel and extrasolar planets as a hook for talking about relativity, thus all the movie images near the beginning. The original idea I had was to look at different fictional ways of evading the ban on faster-than-light travel, but they wanted something more in the half-hour range than the hour-long talk I was originally envisioning, so I had to cut it way back.

The problem with using space travel as an intro to relativity is that it's easy to come off as a total killjoy, saying we'll never reach other stars. My original plan was to offer causality as a reason why you ought to be happy about the ban on FTL travel-- if you can move faster than the speed of light, than some observers will necessarily see effects happening before their causes, which would just be bizarre. I didn't really have time for that, though, so instead I offered the Global Positioning System as an example of a useful application of the constant speed of light. With a bit of local pandering, as you can see from the maps toward the end.

I probably overshot the actual level of the audience-- I was aiming for the upper end of middle school, but one of the larger groups in the audience on Friday was probably in fourth grade, so it pretty much went over their head. On the other hand, though, one of the actual middle-schoolers there (I'd guess about eighth grade) came up to me after the talk and said "Thank you so much! That's the first time any of this made sense." Which is a great feeling.

(I said "Thanks, that's really great to hear. And, have I got a book for you...")

So, anyway, that's how I spent the latter part of my week. And if anybody would like an hour-long talk about relativity using fictional space travel as a hook, drop me a line, and we'll see if we can make that work, because I've got the idea, now, and would like to actually do it at some point...

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Ha, I correctly guessed the GPS link with the circles from Dallas, Austin, etc.

Did you ever make the joke of "I put Houston in my GPS and got _____ instead"?

What a hoot! I love slides 5 and 6!

By CCPhysicist (not verified) on 03 May 2014 #permalink

Did you ever make the joke of “I put Houston in my GPS and got _____ instead”?

That's the slides with concentric reddish circles over a map of Houston. The circles represent the 11 km/day error of GPS without correction for relativistic effects, and I noted that after a bit more than a week, you could be trying to come to see giant rockets in Houston, and end up out in the woods looking at a giant Sam Houston (in the national forest). That got some chuckles.