Tuesday 2 April 2019

Cosmic Circumnavigation?

Poul Anderson, Tau Zero, CHAPTER 17.

"'A tau so low that we can actually circumnavigate the universe...in years or months.'" (p. 149)

To circumnavigate the globe by the shortest route, I would travel forward veering neither to left nor right until I arrived at the exact point from which I had started. Is the structure of cosmic space such that a vehicle traveling forward veering neither to left nor right, up nor down, would eventually return to its starting point? The Earth's surface is a two-dimensional area around a three-dimensional globe so is cosmic space a three-dimensional volume around a four-dimensional hyper-globe?

Don't ask me.

An image of Magellan's circumnavigation is appropriate since we refer to the Magellanic Clouds.

Lunch with Ketlan, then a walk followed by meditation, evening meal and more blogging. Gods willing.

3 comments:

Sean M. Brooks said...

Kaor, Paul!

I'm quite UNABLE to answer the questions you posed here! And, in the real world, Magellan could NOT simply sail straight west till he again arrived at his departing point. He had to zigzag north or south to get around land masses such as South America or Africa.

Sean

Jim Baerg said...

As I recall what cosmologists were saying a few decades ago, a Universe that eventually collapses *would* be 'curved' in a way that would make it 'finite but unbounded' like the surface of sphere and so allow 'circumnavigation'.
What the accelerated expansion of the universe does to this I'm not sure, but I suspect it would mean no circumnavigation would be possible at any time.

Sean M. Brooks said...

Kaor, Jim!

Th idea of circumnavigating the universe boggles me!

Ad astra! Sean