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Freakaholic
05-06-2007, 04:56 PM
Interesting video explaining how to try and understand the 10th dimension and those underneath it. (http://www.tenthdimension.com/medialinks.php)

Kinda lost me at some point. I mean, it makes sense, but its hard to keep everything underneath it in its place while tying to grasp each new dimension. Still informative and gets me excited for the upcoming Flatland Movie (http://www.flatlandthemovie.com/).

Edward
05-06-2007, 07:07 PM
Good fun but not really clear or correct. The text at the end of the video gives it away!

Flatland looks cool, I like how the voiceover describes "the 3rd dimension" as if it's the most exciting thing ever. (i know that's the point, that to a flatlander it would be mindblowing but it's still a funny idea)

Freakaholic
05-06-2007, 07:23 PM
Good fun but not really clear or correct. The text at the end of the video gives it away!


I kinda figured that one. But my learning of probability statistics and quantum mechanics stopped way to soon to really undersand all this. I think its a nice intro into something that most people would completely ignore because its too "complicated". Along the same lines as Hawkins' "Universe in a Nutshell" - which is a lot prettier.

Another book which I thought "dumbed down" complicated topics well enough to make them understandable and interesting was The Jungles of Randomness (http://www.amazon.com/Jungles-Randomness-Mathematical-Safari/dp/0471164496) on chaos theory and its applications in modern life.

Any other suggestions?

Mr. Tea
06-06-2007, 02:05 PM
It's scarcely 'dumbed down', but Murray Gell-Mann's The Quark And The Jaguar is an excellent approachable-but-not-lightweight intro to, well, all sorts of stuff, but with a particular emphasis on complexity theory, information theory and quantum mechanics. Well worth a read.

Freakaholic
06-06-2007, 07:30 PM
This got me to thinking.

In what dimension would a being need to exist in order to appear omnipotent in ours?

Edward
06-06-2007, 08:20 PM
Is that a serious question?
It doesn't make sense to me. :-/

Mr. Tea
07-06-2007, 12:50 PM
This got me to thinking.

In what dimension would a being need to exist in order to appear omnipotent in ours?

N+1, as far as any N-dimensional being is concerned. So 4, in our case (assuming only 1 time dimension is allowed in any physically meaningful universe!).

Imagine being a Flatlander. You could be imprisoned in a square cell, with no way of escape. If you had a 3-dimensional cell-mate, you might not realise it at first because his 1-dimensional projection that you could see might look just like the 1-d projection of any 'normal' 2-d being. (Remember we actually see 2-d projections of 3-d objects).
But he could escape the cell at any time by 'disappearing' (moving through higher-dimensional space) and 're-appearing' (coming back down so part of him re-intersected the 2-d plane of Flatland) and hey presto! He's escaped from a sealed prison cell. Magic.

vimothy
07-06-2007, 01:16 PM
Makes me think of the Invisbles and all that times travel stuff they end up doing...

Mr. Tea
07-06-2007, 01:22 PM
Makes me think of the Invisbles and all that times travel stuff they end up doing...

Is that you, Parsons?
Is this me?

:)

swears
07-06-2007, 01:58 PM
Is it physically posssible a fourth spacial dimention to exist?
Like breadth, width, length and .....?

Mr. Tea
07-06-2007, 02:09 PM
Is it physically posssible a fourth spacial dimention to exist?
Like breadth, width, length and .....?

At the risk of sounding like certain critical theorists popular in these parts, it depends what you mean by 'exist'.
There clearly isn't a macroscopic fourth dimension - we'd certainly know about it if there were - but it's certainly possible that one or several extra dimensions exist on a very small scale, 'curled up' on themselves (so each would have the topoglogy of a sub-atom-sized loop, rather than a Euclidian line stretching off in either direction to infinity).
So far this all applies to our (3+1) universe (where the numbers refer to 3 normal (macroscopic) space dimensions and 1 time dimension). Hypothetically, you can do physics in a universe with any number of space dimensions (well, 'zero' might be a bit tricky, but let's say 'one or more'), although they'd have radically different laws of physics from our universe. In fact, the fact we have three dimensions - which appears to be the optimal number to allow stars, planets, complex systems and ulitmately intelligent life to evolve - is taken by some as evidence of 'fine tuning', which is a problem related to the anthropic principle.

swears
07-06-2007, 02:17 PM
...is taken by some as evidence of 'fine tuning', which is a problem related to the anthropic principle.

Is that something to do with intelligent design? Like the universe is so precisely governed by physical laws that it had to be created by an intelligent entity? Of course to counter this argument you could say that there has been an infinite amount of time and perhaps an infinite number of universes (in the multiverse) for this "fine tuning" to occur.

Mr. Tea
07-06-2007, 02:40 PM
That's pretty much the idea. Some people have used fine-tuning to argue for ID, as you say, although many people are coming round to the idea that when we have a more complete picture of how the various elementary quantum fields arise (string theory, perhaps) that it may well turn out that the values for various physical parameters (speed of light, mass and charge of an electron, etc.) are not arbitrary at all, but can be calculated from first principles. In other words, they are that way because they couldn't be any other way.

A good example of this is the so-called flatness problem, which is the question "why is the overall density of the universe apparently exactly equal to the critical density". The critical density is the density that will cause the expanding universe to 'eventually' come to a standstill at an infinite time in the future, when it is infinitely big. This has been a major headache for cosmology, since the models predict that the early universe would have immediately collapsed back on itself if its density were just a tiny fraction greater than critical, and expanded so rapidly that stars and galaxies would never have formed if it were only a tiny fraction less. Then a new improved Big Bang model came along that incorporated a brief but exponentially rapid period of expansion, called inflation: this solves the flatness problem by saying that any initial non-flatness was very quickly 'ironed out' as the universe exponentially expanded.

I should add that this is still a very much ongoing, and somewhat controversial, area of research.

Edward
07-06-2007, 06:19 PM
N+1, as far as any N-dimensional being is concerned. So 4, in our case (assuming only 1 time dimension is allowed in any physically meaningful universe!).


This would make you able to do some freaky thing but it wouldn't make you omnipotent. There are still plenty of things you couldn't do.
That was why I didn't understand the question.

pernickety

tryptych
07-06-2007, 06:42 PM
At the risk of sounding like certain critical theorists popular in these parts, it depends what you mean by 'exist'.
There clearly isn't a macroscopic fourth dimension - we'd certainly know about it if there were - but it's certainly possible that one or several extra dimensions exist on a very small scale, 'curled up' on themselves (so each would have the topoglogy of a sub-atom-sized loop, rather than a Euclidian line stretching off in either direction to infinity).
So far this all applies to our (3+1) universe (where the numbers refer to 3 normal (macroscopic) space dimensions and 1 time dimension). Hypothetically, you can do physics in a universe with any number of space dimensions (well, 'zero' might be a bit tricky, but let's say 'one or more'), although they'd have radically different laws of physics from our universe. In fact, the fact we have three dimensions - which appears to be the optimal number to allow stars, planets, complex systems and ulitmately intelligent life to evolve - is taken by some as evidence of 'fine tuning', which is a problem related to the anthropic principle.

Couldn't there be a macroscopic 4th space-like (as opposed to time-like) dimension...? As in a 3-sphere projection? (Not that I'm saying that there aren't anthropic reasons why we don't have macroscopic extra dimensions)

Swears: Length, breadth, width, and ... other. It's pretty difficult for an agent trapped in a 3+1 universe to conceive of dimensions beyond that. I find considering tesseracts, their transformations and nets can help give a flavour:

http://en.wikipedia.org/wiki/Tesseract

Mr. Tea
08-06-2007, 02:11 PM
Couldn't there be a macroscopic 4th space-like (as opposed to time-like) dimension...? As in a 3-sphere projection? (Not that I'm saying that there aren't anthropic reasons why we don't have macroscopic extra dimensions)

It's possible that there could be dimensions in which gravity alone interacts, whereas all the other fields (eg. the matter we're made of, the light we can see etc.) is confined to three space dimensions.
Various experiments have shown that if gravity-only extra dimensions exist, they must be smaller than about a milimetre (which is obviously many, many orders of magnitude larger than the truly 'small' extra dimensions required in string theories, for example).


Swears: Length, breadth, width, and ... other. It's pretty difficult for an agent trapped in a 3+1 universe to conceive of dimensions beyond that. I find considering tesseracts, their transformations and nets can help give a flavour:

http://en.wikipedia.org/wiki/Tesseract
[/QUOTE]
I would say 'impossible' rather than 'difficult', if we're using a strict definition of 'conceive of' - but tesseracts are pretty groovy. The animations on that page look like something from an Autechre video. :)

tryptych
08-06-2007, 04:05 PM
If you want really mind-melting, try looking at these 3D nets of 4D polytopes:

http://www.weimholt.com/andrew/polytope.shtml

120 cell polytope, which is what a 4D object made out of 120 3D dodecahedrons folded out "flat" in 3D space would look like.

Oh, here's an animation of a icositetrachoron (24-cell polytope) too, performing a double rotation in two planes, since you like that so much:

http://upload.wikimedia.org/wikipedia/commons/f/f4/24-cell.gif

Hmm, new avatar methinks... EDIT - arse no animated avatars allowed...

Greg Bear's short story "Tangents" (from the collection of the same name) has some nice descriptions of 4-D enities passing through the 3D plane, if I remember right.