h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

http://www.newscientist.com/article/mg20126911.300-our-world-may-be-a-giant-hologram.html?full=true

One thing puzzles me (well, okay, more than one), how can a five-dimensional universe be "shaped like a Pringle"?

TRiG.

In the old days, they would have said "shaped like a saddle" or "shaped like a col" but obviously pringles are more familiar to the modern reader.

To be honest it isn't really meaningful I think.
It is just a way to try and explain the concept to those of us who do not have the necessary grounding in maths and theoretical physics.
Also, don;t forget it is a model of the universe. Doesn;t mean the universe actually is like that, just that this model is and that that helps us explain things a bit better.
There are very, very, very few people who can actually visualise more than 4 dimensions. So what is actually being referred to is the shape as shown in a 3d representation of 5d. I certainly can't visualise 5d and I'd very suspicious of anyone who is not a top class mathematician or on some very powerful drugs who said they could.

Even mathematicians researching space-time use paper models to model gravitational effects etc. For some reason it seems to nicely represent the way in which space and time is distorted.

I suppose it's because it's a double-curved shape, which can't really be accurately drawn in cartesian space. (A real problem in architecture, when someone designs a roof or something that you can't show in an elevation and a section...)

Congrats on Quote of the Day.

Obviously, the answer is that Pringles have a complex higher-dimensional structure, of which we can see only a cross-section. If you had an understanding of Quantum Pringle Dynamics, you'd understand that.

Gif

If you master the Pringle Universe Model of course the next iteration in compextity is the McKoy Model where the universe is envisioned as several pringle like dimensions.

Crinkly if you can picture it

What flavour?

Now that's the *real* question. If it's barbecue, I'm moving!

Step 1

Imagine the universe as a flat sheet of some bendy substance. Rubber is good. Now, mark a point on it, and with a good sharp knife, cut a line from that point out to the edge of the universe. Take a long thin triangle of rubber, say with the narrow angle as about 5 degrees, and insert it into the cut you've made so that the point of the triangle meets the point you marked. Join up all the edges.

You've added some extra space around the point. If you trace a circle around the point, you'll find that its circumference is longer than it should be given the radius. Of course the sheet won't lie flat any more and will naturally shape itself into the shape of a saddle, col or pringle.

Step 2

The next step is to do the same procedure as step 1 but at every point on the sheet. Each point has a bit of extra space added around it. Now you can draw a circle at any point on the sheet and its circumference will be slightly greater than it should be. You can also analyse triangles and you'll find that the angles add up to slightly more than 180 degrees. You've arrived at the 2-d universe in the shape of a pringle at every point.

Step 3

The final step is harder to describe as it requires thinking in 4 dimensions. Cut a slit in 3-d space, and insert a narrow cone into the slit, sewing it all back up, so that there is now more space around the point in 3-d space than you would expect. Drawing a sphere around the point, you'll find it has more surface area than expected. Repeat the procedure at every point in the 3-d universe. You've now got a 4-d universe "shaped like a pringle".

You also need a good pair of scissors!

Wahay! My very first QotD.

I shall never cease to marvel at Gnomon's ability to explain everything.

TRiG.

Congrats, TRiG...welcome to the big boys club!

Are Hallmark producing "Congratulations on your first QOTD" cards yet? Gap in the market there.

'Happy Quote-day to you. Happy Quote-day to you. Happy Quote-day dear TRi-hiG, 'Happy Quote-day to you.'