- 21 Mar '16 12:16 / 13 edits

If our universe is not the only one then perhaps our universe could be moving in some higher dimensional direction relative to some other universe ?*Originally posted by twhitehead***That is an illogical question. For the universe to be moving, it has to move relative to something else. But the universe is everything by definition.**

Or perhaps our universe could be spinning around some arbitrary axis of rotation within itself as define in terms of a centrifugal force causing outward acceleration? (really not sure if there is something conceptually wrong with that )

But here is an illogical question:

why can't all of something be moving leftwards only relative to itself? - 21 Mar '16 14:00

Setting aside the question of the exact definition of 'universe', movement involves time so these other dimensions must in some way interact with the time dimension of our universe. It just doesn't make a whole lot of sense.*Originally posted by humy***If our universe is not the only one then perhaps our universe could be moving in some higher dimensional direction relative to some other universe ?**

**Or perhaps our universe could be spinning around some arbitrary axis of rotation within itself as define in terms of a centrifugal force causing outward acceleration? (really not sure if there is something conceptually wrong with that )**

That is certainly interesting. But when you say 'spinning' you might still encounter the question of 'in relation to what?'.

I must also note that there is no evidence yet as to whether the universe is finite or infinite. - 21 Mar '16 18:24

Yet it is estimated to have a certain 'size', several times bigger than what we see with scopes and such.*Originally posted by twhitehead***Setting aside the question of the exact definition of 'universe', movement involves time so these other dimensions must in some way interact with the time dimension of our universe. It just doesn't make a whole lot of sense.**

[b]Or perhaps our universe could be spinning around some arbitrary axis of rotation within itself as define in terms of a centrif ...[text shortened]... I must also note that there is no evidence yet as to whether the universe is finite or infinite.

What if universes were like bubbles of foam and somehow jostling for position with each other, bumping into and out of some kind of surface tension layer that keeps other universes from just becoming part of ours. - 21 Mar '16 19:40

Why would that be a stretch? If there are multiple universes it would seem each one would have it's own internal clock that started at each BB where our universe could be 10 billion years later than another universe in terms of its overall evolution. And just as easily 10 billion years behind the clock that started in yet another universe, ad infinitum.*Originally posted by humy***-unless the higher dimensions include a time dimension of their own. -OK, that's a stretch.** - 21 Mar '16 19:42 / 1 edit

If I spin, I would feel the effects of spinning (outward force ) even if everything was spinning around with me on the same axis of rotation so that nothing is not spinning in relation to me. I see no problem in saying something can spin in relation to some arbitrary axis of rotation within itself so that spin is not 'in relation' to anything else outside that something in particular.*Originally posted by twhitehead***But when you say 'spinning' you might still encounter the question of 'in relation to what?'.**

. - 21 Mar '16 20:52

'It is estimated' by whom? Based on what? I bet you can't actually find a reference for that that includes anything more than wild guesswork not based on actual evidence.*Originally posted by sonhouse***Yet it is estimated to have a certain 'size', several times bigger than what we see with scopes and such.** - 21 Mar '16 22:01 / 1 edit

I meant there being a time dimension being*Originally posted by sonhouse***If there are multiple universes it would seem each one would have it's own internal clock...***between*the universes in higher dimensions thus independent on the time dimension of each universe; I think that would be a stretch. - 22 Mar '16 07:05

It is not the total volume of the universe that is known to be expanding but rather the space within the universe is known to be stretching.*Originally posted by vivify***Doesn't the fact that the universe is expanding mean the universe isn't infinite?**

**Something of infinite size can't get continue to expand, can it?**

Well that does depend on how you define expansion. Multiply all numbers by two and the number-line appears to expand locally. Its total length does not increase because its total length is not defined. - 22 Mar '16 09:19 / 2 edits

infinity often confuses people;*Originally posted by twhitehead***It is not the total volume of the universe that is known to be expanding but rather the space within the universe is known to be stretching.**

[b]Something of infinite size can't get continue to expand, can it?

Well that does depend on how you define expansion. Multiply all numbers by two and the number-line appears to expand locally. Its total length does not increase because its total length is not defined.[/b]

if you multiply infinity by any finite number, you just get infinity; exactly the*same*infinity. Of course, this is not something we can actually visualize and this is the main causal factor in the common layperson confusion over infinity.

There is the highly implicit layperson erroneous assumption of "if I cannot visualize it, it must necessarily be nonsense". - 22 Mar '16 10:47

Except that by standard definitions you cannot multiply infinity by a number because infinity is not a number. There are definitions to extend standard definitions to deal with infinity, but it must always be recognised that they are extensions and have subtly different properties.*Originally posted by humy***infinity often confuses people;**

if you multiply infinity by any finite number, you just get infinity; - 22 Mar '16 10:50

The problem of visualization is hardly unique to lay people. Many famous scientists / mathematicians have got things wrong and or refused to accept something because they could not visualize it.*Originally posted by humy***There is the highly implicit layperson erroneous assumption of "if I cannot visualize it, it must necessarily be nonsense".**