Many have asked the question: what is the universe
expanding into? Most consider that as the universe expands
it creates space in this process, so there is nothing outside
the expanding universe. However this assertion is by no means
certain, as our concepts of space,time,etc, may not be correct.
Any comments?

I'll tell you what i read many months ago

Galaxies are receding away from us, the milky way, i think astronomers thought that we were the centre of the galaxy and something like dark matter or sometyhing was probably around here and thats why, but i forgot the reason why they were moving away, and no we're not the centre. This is also evidence that the Universe is expanding coz galaxy's are receding from us. If they're moving away, that means that the Universe is expanding, supposedly!

It's not expanding into anything, and its expansion is in more than 3 dimensions so it is difficult to try and visualise. Think of 4 dimensional space wrapped around a 5 dimensional ballon that is being pumped up and you might get close.

Kashi

__________________
Climate Change Australia

We live in a 3d world. We can see in all directions forwards backwards left right and so on!
In a 4d world, i think it might be a bit difficult to comprehend because we live in a 3d world. You could probably see through things, or around them...Like a balloon, you could probably see it as a whole the entire shape, in a 3d world you can't.
Thats just my theory.

The assumed idea that is considered as the correct scenario:
The universe is expanding into nothing,just as you said,Kashi.
The point that I am making is that this is not 100% certain.

4D is standard 3D but with time thrown in. Time is the fourth dimension and so space-time as we know it is 4D. We haven't proven 5D, or any other dimension, but we think that there might and probably are other dimensions.

__________________
MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

That is a popular misconception. According to string theory ordinary space consists of four spatial dimensions and one temporal one (see http://focus.aps.org/story/v1/st7 and http://www.mkaku.org/articles/hyper_and_toe.shtml ).

We, being 3-D beings, can't conceptualize 4-D space anymore than Flatlanders could conceptualize 3-D space.

Dave Mitsky

__________________
Chance favors the prepared mind.
De gustibus non est disputandum.
Never attribute to malice that which can be adequately explained by stupidity.