## Tag Archives: curved space

### Finishing Feynman Early

Have you ever finished what you thought of as a monumental (intellectual or otherwise) task early — such as finally writing up that paper, senior thesis, grant proposal etc. etc.  Well I just did.

It was finishing volume II of the Feynman Lectures on Physics on electromagnetism earlier than I had thought possible.  Feynman’s clarity of writing is legendary, which doesn’t mean that what he is writing about is simple or easy to grasp.  Going through vol. II is pleasant but intense intellectual work.

The volumes are paginated rather differently than most books.  Leighton and Sands wrote up each lecture as it was given, so each lecture is paginated, but the book isn’t paged sequentially.  Always wanting to know how much farther I had to, I added them together producing a running total as I read the book.  FYI  the 42 lectures (chapters) contain 531 pages.

So I’m plowing along through chapter 37 “Magnetic Materials” starting on p. 455 with its 13 pages knowing that there are still 63 intense pages to go at the end when I get to the last paragraph which begins “We now close our study of electricity and magnetism.”

Say what?  The rest is on fluid dynamics and elasticity (which I’m not terribly interested in).  So I’m done.  I feel like WilE Coyote chasing the roadrunner and suddenly running off a cliff.

However, the last chapter (42) is not to be missed for any of you.  It is the clearest explanation of curvature and curved space you’ll ever find.  All you need for the first 7 pages (which explains curvature) is high school geometry and the formula for the area of a circle (2 pi *r) and the volume of a sphere (4/3) * pi * r ^3.   That’s it.  Suitable for your nontechie friends.

Of course later on he uses the curvature of the space we live in to explain what Einstein did in general relativity and his principle of equivalence and his theory of gravitation (in another 7 pages).  I wish I’d read it before I tried to learn general relativity.

I did make an attempt to explain the Riemann curvature tensor — but it’s nowhere as good.

Here are links to my other posts on the Feynman Lectures on Physics