(no subject)

[puddingcat]

xambrius has just made me realise something.

One theory of the universe is that it has 10 dimensions; 3 along each visible axis, and the tenth being time. How appropriate that we're on the Tenth Doctor :)

Comments

[westernind.livejournal.com]

Don't understand the difference between a visible axis and a dimension. Surely they're the same thing?

[puddingcat.livejournal.com]

The theory is that the extra ones are rolled up inside (possibly outside) the visible ones.

Extrapolate the idea that a 2-dimensional being wouldn't understand how walking in a straight line round a ball could bring them back to the starting place. Then blowing up a straight line (traditionally one-dimensional) could leave it looking a bit like a pencil - you could walk around its circumference (one extra dimension) or along the length, round the point, back along the underneath & round the blunt end (the other extra dimension). It still *looks* one-dimensional to us, becasue we're 3-D beings, but the extra ones are there inside anyway.

Brian Green expains it better in "The Elegant Universe". I can accept it the same way I can accept quantum duality and wasabi filling in chocolate cake (they shouldn't work, but they do).

la la la

[westernind.livejournal.com]

Would I be right in thinking that this theory is needed to make the physics work - i.e. make predictions? But is not needed in order to accomplish tasks such as navigating to the bus stop and eating chocolate?

Re: la la la

[puddingcat.livejournal.com]

Unless the bus stop and chocolate are on the scale of Planck's constant (see nmg), then probably not. But if you *do* find yourslef walking in teeny weeny spirals, you'll know why :)

[nmg.livejournal.com]

In string theory, and its offspring M-theory, it is assumed that there are as many as eleven dimensions, but that some of these are 'rolled up' smaller than the Planck length and cannot be observed.

A common analogy for this is to consider a piece of garden hose. From a distance, it appears to have only a single dimension, its length. Close up, there is another closed dimension, namely its circumference.