Ep. 81: Questions on the Shape, Size and Centre of the Universe

Listener Questions credit: Rebecca B-F

As predicted we got a lot of questions from people about our trilogy of shows on the size, shape and centre of the universe. Today we'll do our best to clear them all up.As always, if you're still confused drop us an email to info at astronomycast dot com. Episode 81: Questions on the Shape, Size and Centre of the Universe (14.7MB)

Show Notes

Check out the shows that caused these questions - and don't forget to look at the show notes.

1. Yuk Says:
   March 24th, 2008 at 11:45 am

   Haven't heard the whole thing yet, but a dodecahedron is a 12 sided polyhedron or a 12 sided dice per your D&D terms.

2. inigo Says:
   March 25th, 2008 at 8:46 am

   I've only just begun listening to the podcast a few weeks ago and its great, my only problem is that Pamelas voices is just too dam sexy and i lose all concentration on the subject.

3. Freiddie Says:
   March 25th, 2008 at 12:51 pm

   Wrapping paper on torus ain't easy. The torus in math and in reality a little different (at least that's how I think I should explain it - I don't really know), since the inner radius of a torus is always < outer radius of a torus, making the wrapping paper crease on the inside part. I wonder if this can still be considered "flat", since wrapper paper doesn't quite wrap a real torus well. (Please clarify this puzzle - I have been so confused by it and can tolerate no longer. Thanks.)

4. KarenX Says:
   March 25th, 2008 at 1:04 pm

   So I get how a star would look different if you looked at it, say, to the right and then turned left to wait for the light to travel around the universe the opposite/long way. But I think the question that prompted the answer was asking something else. That is, I think I want to ask something else.

   So I'm looking at a star from point A. The star is 10 million light years away. Let's say I travel really fast in a straight line towards the star, pass through the center, and go another 10 million light years. If I turn back and look at the star from this direction, will it look the same as it did at point A? If I travel back to the center of the star and move straight up for 10 million light years and look down on the star, will it look the same?

   My instinct says yes because I would think that a sphere would burn more or else consistently all over its surface. My brain tells my instinct not to be so cocky but can't say why. Would the star look the same if you observed different sides of it from the same distances?

5. Taras Says:
   March 26th, 2008 at 3:07 pm

   Karen, some stars are rotating so fast, that they bulge at the equator, and would look slightly different from different vantage points.

6. Jason Creighton Says:
   March 30th, 2008 at 2:03 pm

   Pamela says in this episode that a megaparsec is "about three thousand light years across". Since a parsec is about 3.2 lightyears, wouldn't a megaparsec be about 3.2 million light years, not 3.2 thousand? Wouldn't 3.2 thousand be a kiloparsec?

7. Mirv Says:
   April 1st, 2008 at 8:58 am

   Whenever I try to picture space having a torus geometry, I think about that old-school video game, Asteroids.

   It's a 2D game, you can fly your spaceship up, down, left and right. When your ship flies past the upper part of the screen, it appears at the bottom. When your ship flies past the bottom part of the screen, it appears at the top; and similarly right to left and left to right.

   Is this space a torus geometry?

8. themondo Says:
   April 3rd, 2008 at 10:51 pm

   It would be nice if people were respective of each other no matter there view point. The univese is a BIG place. So there are alot of scenarios that can be had, even the imaginative are not to be discounted. That's why we have fiction (no matter what catagory) and it could possibly be true if you suggest it. I like all therories but some have to be questioned, others dicounted, some discredited and others (most of them) looked at seriously. So can we not look like we're talking to some one who doesn't know anything about cars and help each other to Know about the vast nature that surrounds us, the universe.

9. Jerry Fox Says:
   April 7th, 2008 at 11:53 am

   A recent issue of New Scientist quoted a comment that time passes more slowly in regions of high gravity. I believe also that as an object approaches a black hole, time for the object is slowed relative to the world outside.

   So what would have happened just after the Big Bang, when the entire universe was, say, the size of a pea? Perhaps one could say yes, time passed _very_ slowly, but since everything was running at the same rate, it didn't matter. But would that affect the speed of light? Would light have taken years to travel this small distance? Does light march to a different drum from the rest of us? - though now the drums are indistinguishable.

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