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

One of the most common questions in the Astronomy part of Yahoo Answers is "What is beyond the edge of the universe?"

I've come up with a way of explaining this, but it's going to take some work, an involves Pacman.

First Pacman, then Pacman on a balloon...

The standard Wall Atlas might help, too, where Alaska is in the top left and right corners.

Zube

Would the lightcycles from Tron be of any help?


Geggs

I never saw Tron.

Google featured a playable game of Pacman on their main page as their Google Logo recently. Does anybody know is this still available?

My explanation usually involves Dr Seuss's "Horton Hears a Who".

You can add 'gadgets' to you iGoogle homepage - if you have one. These include some pacman games:

http://www.google.com/ig/directory?q=pacman&root=/ig&dpos=top

If this would be the entry that the title implies to me, you may find some helpful stuff in: A3006307

Here's a direct link to google's pacman page. http://www.google.com/pacman/

FordsTowel, that was a fascinating article. I found it quite intriguing. http://wp.me/p16myI-3o.

TRiG.

Yes indeed. Thanks FT for that.

Another approach that may be helpful is the psychological. This was pioneered by Berkeley A3472986

Time is seen as one-directional because we cannot perceive it otherwise. We construct our personalities from our history, and if something upsets the linear progress of our story, we have to adjust our story to accommodate it -- a contradiction is not tolerable.

Wittgenstein gave an example: a chair suddenly disappears, and we say 'it was never really there'. It reappears and we say 'it was there all the time, the disappearance was an illusion'. There need be no end to these explanations.

Time according to Berkeley is 'the succession of ideas in the mind' and we see it as unidirectional because we need a graspable succession -- for our own comfort and survival.

Seeing the whole universe as one is what Wittgenstein called 'the mystical'. It is easy to imagine doing that in a disinterested way, but not so easy to do. If it were possible, there would be no succession. The outcome of any game of Conway's Life is included in its starting state http://www.conwaysgameoflife.net/ and if we could imagine the universe as a big game of life, perhaps that is true of the universe too; but this is not a simple supposition. What counts as an atomic event in the evolution of the universe? What size are the pixels?

Perhaps we should say like Kant 'there may be no boundaries, but we are not in a position to imagine that, as our imagination requires boundaries.'

Conway's "game of life" is a deterministic universe, but there are two things counting against our universe being deterministic: the theory of chaos states that arbitrarily small changes in the initial state can produce major changes in the later state of the universe, so we can never predict even in a completely Newtonian universe. The other thing is the random elements introduced by quantum mechanics.

But I wasn't really planning on speculating on the nature of time, only on the spatial dimensions which are what give people the real problems in terms of understanding.

So... you're maybe thinking that our universe is mostly well bounded except for possibly two points at either end that connect so that if we pass beyond the edge on one side we appear to enter from the other?

WOCKA-WOCKA-WOCKA

No, I was thinking of equipping Pacman with a shovel and pick, and asking him to dig, dig, dig, dig, dig, the whole day through.

Oh, no... that's DigDug.

"arbitrarily small changes in the initial state can produce major changes in the later state of the universe, so we can never predict even in a completely Newtonian universe" -- true, but this is not an argument against our universe being deterministic. It is an argument against its predictability in practice, but not in principle.

I think it is, because you can never know the state of the universe exactly. It's not that the better we know the state of the universe the more accurate our predictions, because we can be vanishingly close to the correct value and still be totally unable to predict the future state due to this "critical sensitivity to initial conditions" better known by its popular name of "chaos".

Yes, agreed; but that is still true of a totally determined universe if it is complex enough. You can have plenty of chaos within a determined system, without relying on quantum quirks. An example of this is the (physically determined) bouncing and emergence of balls in a lotto tumbler. It's not random, but it's plenty random enough.

A favorite variation on the 'bouncing ball', the 'iso-entropic bouncing ball' from the film, "Men in Black", proof positive that only an expanding universe can have conditions of stability.