View Full Version : Ep. 77: Where is the Centre of the Universe?

2008-Feb-26, 04:10 AM
There are some people Ė Iím not naming names Ė who think the universe revolves around them. In fact, for most of humankind, everybody thought that. Itís only been in the last few hundred years that scientists finally puzzled out that the Earth isnít the centre of the universe at all. That begs the question: where is the centre?http://feeds.feedburner.com/~r/astronomycast/~4/241265349

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Steve Limpus
2008-Feb-27, 09:09 AM
Fraser and Pamela and the crew,

Wow, I LOVED this show... this is the very question that led me to Astronomy Cast (thanks Google!) then after listening to the shows, surfing some more, reading some great books, chewing things over sometimes with the wonderful folk here in the forum, I've learnt SO much, and I'm sure this interest will stay with me for life. I plucked up the courage to email you guys once and you were so nice replying and all... I printed your email out and still have it on my bookshelf.

Thanks again, just can't wait 'til next week!

All the best.

2008-Feb-28, 01:15 PM
I was greatly pleased that some of the "thoughts" I had years ago were confirmed thoroughly in this episode. Almost word for word. AWSOME!

2008-Feb-28, 06:22 PM
I love the idea that the centre of the universe exists in the 4th dimension. I wonder if there are higher dimensional beings who regularly tunnel through our universe without us noticing?

2008-Mar-02, 11:50 AM
Loved the historical introduction, right on the money

Indeed it goes to the hart of the podcast that explains ďhow we know what we knowĒ

2008-Apr-21, 01:58 AM
I just reviewd Podcast 77: "Where is the center of the Universe?" I am disappointed to see that it was headed in exactly what I suspect was the correct direction only to drift off into the ditch and never got back on track. So close and yet so far.

It progressed unerringly to the following dialog:

. Fraser: Okay. Here’s where the show turns and the unhappy answer comes. Where is the centre of the universe?
. Pamela: Nowhere we can experience.

It was good up to that point. It had reached the model for which I argue in my thread entitled "What is the shape of the Universe", in which I described what impresses me as the most plausible geometry for the Universe, a four-dimensional hypersphere whose three-dimensional "surface" is the three-dimensional Universe that know. It had even mentioned the point in the center of the hypersphere, the point equidistant from all points on its three-dimensional "surface". If only it had identified that point as the center of the Universe, a point not in our three-dimensional point at all but equidistant from all points in it, then I would feel that it gave what appears to me to be the best answer to the question in the title of Podcast 77. So close, only to wonder off with such a meaningless answer as "everywhere and nowhere".

Then, instead of getting back on track, it wondered off into the wilderness with the following:

. Fraser: So, you can hold a ball in your hand. If you say to yourself, what is the centre of the surface of the ball, the answer is nowhere
. because in any direction you go on that ball, you’ll come back to your starting point in an equal amount of time or distance.

"of the surface" is what derailed the discussion. The center of a ball isn't on its surface.

2009-Jan-09, 02:44 AM
hmmm ... OK, I've listened to the centre, shape, size trilogy (cast 77,78,79) - am I understanding correctly that we just don't know if there's a centre or not?

2009-Jan-09, 12:16 PM
I think the center is not where, rather when...

Lord Jubjub
2009-Jan-10, 09:15 PM
I think the center is not where, rather when...

Drop the 'I think'. The center IS when, not where.

2009-Jan-10, 10:53 PM
hmmm ... OK, I've listened to the centre, shape, size trilogy (cast 77,78,79) - am I understanding correctly that we just don't know if there's a centre or not?

No. According to out understanding of the geometry, there is no "center." Let's reduce the dimensions and say we live in 2-D. So picture a sheet of paper. The surface of a flat sheet of paper obviously has a center. However, now take that piece of paper and wrap it around until all the edges meet (you can't actually do this with a square, but let's pretend you could, or say you're using something like a beach ball instead).

The surface is still 2-D. However, it's warped in a higher, third dimension. Now that surface, which when there actually were edges and had a center, no longer does.

That's the thinking of our universe, that we're in 3-D, but that 3-D "surface" is warped in a 4th spatial dimension such that there isn't really any center.

2009-Jan-19, 01:44 PM
I understand the 2D balloon surface analogy in 3D space, as well as the "when, not where", but I still get the sense that these are still just inconclusive theories.