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Optics in a Closed Universe



In reading the classic book The New Mr. Tompkins I came across a passage on how optics work in a closed universe, a spherical one. If you aren't familiar with the book, the original was written by George Gamow. Mr. Tompkins is a layperson who attends some lectures on relativity given by "the Professor". He dozes off from time to time during the lectures and imagines stories about the topics addressed. Here's a passage from the book I refer to:

"Now, if you think about the globe, you will see that the straightest line on its 
surface,
the meridians, first diverge from one pole, but, after passing the equator, begin to
converge towards the opposite pole. If the rays of light travelled along the meridians,
you, located for example at one pole, would see the person going away from you growing
smaller and smaller only until she crossed the equator. After this point you would see 
her
growing larger; it would seem to you that she was returning, albeit going backwards. 
Once
she reached the opposite pole, you would see her as large as if she were standing 
right by
your side. You would not be able to touch her, of course, just as you cannot touch the
image formed by a spherical mirror."

I would think the opposite would happen. She grows larger until getting to the equator,
then smaller. Comments?

The book has not introduced spacetime diagrams, but I would think the sphere referred to is one. A meridian would be a spatial axis and another 90 degrees from it a time axis. I would think, perhaps wrongly, that a person traveling through space would like like an arc between two meridians.


-- Wayne T. Watson (121.015 Deg. W, 39.262 Deg. N, 2,701 feet, Nevada City, CA) -- GMT-8 hr std. time, RJ Rcvr 39° 8' 0" N, 121° 1' 0" W

       "If I'm given six hours to cut down a tree, then I spend four hours
        sharpening my axe." -- Abraham Lincoln

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