# Wormhole Trouble

1. Jan 10, 2009

### Charlie G

I was watching the Universe and it was talking about the wormhole concept. I was uncomfortable with the images of a wormhole because the spacetime folded over itself, and I was wondering how we got the idea that spacetime folds over itself? I never really imagined spacetime to do that.

2. Jan 10, 2009

### tiny-tim

Hi Charlie G!

If you mean the diagram like a U on its side, with a little tube connecting the top and bottom,

then that "fold" isn't physical … it's just a convenient way of trying to draw something that can't be drawn …

you should regard the curvy bit as if it was flat.

3. Jan 10, 2009

### Charlie G

Thx for the reply. If I look at it as flat though then how does the wormhole connect to another area?

4. Jan 10, 2009

### tiny-tim

'cos it just does!

(the space in the picture, round the U, doesn't exist … the U is our universe, and it isn't "embedded" in some higher-dimensional space)

5. Jan 10, 2009

### yuiop

.. or use a U shaped worm hole :-/

6. Jan 11, 2009

### Charlie G

Thx for the help. I bought the episode cosmic holes on my xbox hoping to learn about balck hole stuff like event horizons and escape velocity, but all the show talked about was wormholes, I was pretty dissapointed in it.

7. Jan 11, 2009

### jambaugh

Remember all diagrams and pictures are analogies. Some of the "folding over" is an attempt to project an analogy of the curved 3-dimensional subspace of a curved 4-dimensional space-time into the flat 2-d screen of a diagram.

Also we tend to think in terms of flat space and so more easily see curvature as occurring inside higher dimensions. For example We in 3-dim looking at the 2-dim curved surface of a sphere from afar find it much easier to conceptualize rather than imagining how walking in a "straight line" on the surface will lead us back where we started or triangles interior angles won't add up to 180deg.

But the extra dimensions is not necessary to describe the curvature mathematically nor is it conceptually necessary for the physics. It is just helpful since the mathematics is not simple nor easy to integrate into our intuition. Also diving ito the mathematical description would be unhelpful in programs on television aimed at the interested non-experts.