We can rule out ignorance off the bat.

Space?

Your mom?

Men With Buns?

What dg said.

"Out there" are big spaces between hydrogen atoms. There's room.

This book is a decent primer on some of the various universe models, both philosophical and scientific, throughout history. But in answer to your question: angels.

Turducken. I know this for a fact.

a parallel universe, obviously--it's smooshing like a silly putty'd image.

/a good a guess as any, no?

angels, ha!

turtles, obviously.

Actually, this has always bothered me.

I read that as "angles".

Me too, Specklet. What do you think that says about our relationship with the divine?

Actually, this has always bothered me.

me too, given the definition of universe being "all which exists" or "the entirety of creation", how is it that anything can "be" outside it or contain it?

When people think about the universe expanding, they wonder if all of the universe is expanding and sometimes they wonder if they're expanding also. Not so. Galaxies, Solar systems, Worlds and people tend to stay the same size because they're bonded together with gravitational forces. Between Galaxies, where there isn't so much gravity to go around, the expansive force is strong enough to break free of this gravitational constraint and the galaxies are pushed away from each other.

As for what is being displaced, well this is a question with answers that cannot be proved or disproved through experiment. As such it isn't really something that can be defined scientifically. My theory is that the universe can be defined as that area of space which is not accelerating away from us at a speed where the light leaving it can never reach us. As such, my answer would be "more universe, only universe which will never affect us and which we can discount from any universal model"

A shorter answer would be "giant bunnies".

Thank you - That was another poorly explained theory from the pop-science world of seanyboy.

what is it displacing? certainly not my festering symptoms of misanthropy

given the definition of universe being "all which exists" or "the entirety of creation", how is it that anything can "be" outside it or contain it?
Because it just can. You have to have faith.

itself

"if the universe is expanding, what is it displacing?"

Nothing.

Next?

so, universe isn't really universe, but only a subset of universe? in other news, god was seen creating a rock that was so large he could not move it.

"If" is a mighty big word. What If the universe is contracting, what's filling in the places where it used to be?

What IF looks could kill?

Besides, I think its probably a combination of spackle and that cool spray foam filler stuff.

Can a subset contain the superset? This is like that episode of Futurama where the two universes had the other one in a box.

or that bugs bunny cartoon where he opens his suitcase and an entire living room pops out.

Another vote for turtles.

Unless it's elephants.

≡ Click to see image ≡

so, universe isn't really universe, but only a subset of universe?
Exactly. Also a superset of universe. Is it clear now?

I saw a NOVA commercial that said the universe has no center or edge.

*boggles*

Actually, I think NOVA is on right now...

If you consider the possibility that the universe is expanding into an alternate universe then we could also assume that the alternate universe is contracting. Sort of the black hole/white fountain kind of thing.

It is best not to think of the universe as "in" anything else. In a sense, this isn't a three-dimensional thing.

Your question was:

if the universe is expanding, what is it displacing?

The Advice Bunny's response is:

Yes, definately!

The question doesn't mean anything, since it can't be answered. How do you divide by zero?

hi i do physics. not this kind of physics AT ALL, but i bet you could ask a carpenter some basic questions about plumbing, as long as you didn't mind the hot water coming out of the garbage disposal when you wanted to take a shower.
the problem here is a difference in our common and technical definitions of words that seem fairly common sense, like measure, dimension, space, and so on. words like boundary or interior. we have our everyday reasoning, where we think of the universe expanding like a jar with some interior volume and some definite delimiting boundary. this obviously poses the question, well, what is that jar sitting in?
this is a common sense understanding of geometry. but geometry can be much weirder than that, and much more painful than what you did in 9th grade with a compass and a protractor. instead of imagining that the jar has to sit in something else, imagine that the jar is everything. so you can't go from being on the glass wall to off that wall on the (common-sense/everyday def'n) "outside," move around, and then go back onto the wall. you can come off that wall you're sitting on and go inside the volume of the jar, but there is no volume outside of the jar.
basically what i am referring to is something aclled the intrinsic v. extrinsiv views of geometry. beginning in the 19th century, several enormous brained germans realized you didn't have to deal with geometrical objects (say, a sphere) by imagining some sort of coordinate system of a space that the sphere sits in (think: before this, people would have an intuitive understanding of the sphere as the subset of points (x,y,z) such that (x^2+y^2+z^2R).
the sphere doesn't "sit" in any space. it just is.
here's the very very concise place to look up differential geometry explantions.

So, the upshot is, stuff can exist and particles can smash into each other and shit can fluctuate and there are women with absolutely tremendous bodies who can exist in a space that's defined on a coordiinate system that makes no reference to some external, higher-dimensional space.
so when we say "the universe is expanding," we're not describing a balloon that's blowing up inside a box and it has to push some air back inside of the box to make way for its increasing volume. instead, that balloon is expanding without existing in some other space. it is the space.

this all seems far more reasonable if you agree to stop thinking that points in real, physical space have to be in a three dimensional euclidean space.
it's actually very likely that we live in a higher-dimensional torus. locally, the space looks very much like E^3, a Euclidean space that follows the axioms of Euclid. But over very long distances, this space will actually obey very different principles -- parallel lines converging, etc, etc.
The neat thing is, the universe is probably not infinite -- if you keep going, you'll come back where you started.





there are implications for time travel. i say this at the end because, if there were a word to describe the response of non-scientist types to this kind of statement from scientist-types, that word would be "apeshit," to borrow from a little gray book.
it's not like with the delorean, though.

The question doesn't mean anything, since it can't be answered. How do you divide by zero?
posted by AlexReynolds 01 November | 20:32

you're hella wrong, liberal arts major!

Oh my college roommate was a theoretical physicist. He studied with Stephen Hawking, yo.

Anyways, he tried to explain this to me quite a few times. I never got it. Then again, he never got neuroscience either.

Basically I have nothing to add to this thread except the namedropping.

"
...Stephen Hawking...
"
every good department has >=1 really obnoxious noble prize winner who goes to seminar/colloquia just to fall asleep in the front row. we've got ours. we sent out good laureate packing to, what, cornell, i think? and prigogine, he dead.

Thank you sam and seanyboy. I shall ponder. Balloons and giant bunnies. Just as I always suspected.

Non-space.

No, the space is there--and totally empty--it's the matter and energy that are expanding, not the universe itself.

At least, that's what I always thought.

This sam person is a smarty-pants. I say we tar and feather him/her, then get out the banhammer, because he/she is showing us up.

Space expands to fill non-space. Look at warbaby's gif. The gray stuff is 3-space (conceptualized in 2-d). The white is non-space, or 4th-dimensional super-space if you prefer. The universe is likely finite but unbounded. Space itself is expanding to fill non-space. Popular examples are dots on the surface of an inflating balloon, or raisins in a rising cake (i.e. one that is being baked) as analogues for points in space. The space itself is expanding.

While we're at it, infinity doesn't mean what you think it means (there's another Inigo shirt idea). Which is larger, the set of all whole numbers, or the set of all even integers? Both are infinite. There's also the set of numbers divisible by five, or the set of numbers that have a "3" in them somewhere. Just because the universe is functionally infinite does not mean that it's every-kind-of-infinite.

So, quonsar wants to know what's outside the raisin cake, right? Does there *have* to be something outside the raisin cake? Nothing really has to be "displaced", right?

Not use of scare quotes.

Or, rather, what I mean to say, that is, is, ahem, "note use of scare quotes".

Note that quotes are not scare quotes in this second instance.

And yes, I'm supposed to be writing about 2400 words right now to catch up for my paltry showing last night. Which is why I'm hanging out here and asking somewhat asinine questions on ask metafilter.

I may be a few decades behind the latest quantumphysics theory, but my mind long ago settled into an acceptance of a Big Bang scenario which started with an incredibly large but not infinite quantity of universe matter packed to absolute maximum density, surrounded by a truly infinite emptyness* that, since the Bang banged, that universe matter has rushed in all directions to fill - but never will.

*what previous posters have called non-space.

42



someone would say it eventually because everything in the universe has existed and will never exist simultaneously.

[on preview: is spell check broken? Safari 2 here]

Well, I know what tonight's nightmare is going to be about. Thanks, q.

Sam, please show us how to divide by zero.

Additionally, please explain how we'll show empirically that we are in a toroidal space when we cannot see beyond the Hubble radius. I had a brief email conversation awhile back with Princeton's J. Richard Gott about this and so far we have no evidence for being able to see "through" the universe to the other side, to see the "backs of our heads", so to speak, and from the current estimated rate of expansion, it doesn't seem likely that we ever could, or will. Asking what the universe expands into is a meaningless question, because the question has no meaning.

≡ Click to see image ≡

Bang. And
the universe expands, hunting
in the darkness slowly for the space
it cannot hold.

Within
on a wet speeding rock he names
the stoned time before him—the silence
before his loud birth

Seven Days
but calls her squirming moments of life
infinite. Within them her cries
are vibrations

the noise that forms
a breeze hunting some freak floating
ember to ignite and catch a

bang.

Nothing is better than a cheese sandwich. But a cheese sandwich is better than nothing.

Nothing is something.

Everything and everyone is just getting further apart, we are displacing love.

surrounded by a truly infinite emptyness* that, since the Bang banged, that universe matter has rushed in all directions to fill - but never will.

*what previous posters have called non-space.

w. -- you're not quite on it, because you're still imagining that there's something outside, just a big emptiness. instead, (if you thikn that the people doing this sort of thing are right and wish to understand what they're doing and all those sorts of caveats), you should think that there was a planck-scale type concentration of mass, and that was the space, and the rules which describe space say that's it. those are the coordinates. if you keep going you'll come back this way, etc. in other words, there's no outside -- vacuum is not the same as no space.
consider an idealized coupled pendulum -- some point in space, with a rigid, weightless bar attatched firmly to it but able to rotate through any solid angle. now stick a weight at the other end. that's pendulum no. 1. now, at that weight, attatch another such fully manipulable pivot, another bar to that, and a weight at the other end. that's pendulum two.
what space does these things live in? it's not E^3, because there are non-zero regions that are inaccessible. This space does not have the same properties as E^3; it's not continuous and not differentiable globally (though one can construct an atlast of locally differentiable maps which completely span the space). So don't think of this construct as sitting in the normal euclidean space -- think of it as sitting in its weird subspace. it can't get out, and, from a certain perspective, there is no out.
now. since this is an example from classical mechanics, there's obviously an outside space that the rest of us live in and buy beer and scracth ourselves. but consider that this situation -- the space is S^2 x S^2, which has certain properties similar to the conventional S^1 x S^1 toroid -- is the same space needed, for, what, a system of two coupled spin one particles? i can't remember if i've got that right. but the point is, for that system, there's no 3-d space to talk of, since the spins are really a sort of bookkeeping for angular momenta (which also, i hate to say it, is not as simple as things whirling about in circles. it's actually something defined by the properties of certain infintesimal generators of kinds of movement -- or more simply put, something is an angular momentum if the relevant commutators obey certain rules.

Sam, please show us how to divide by zero.
posted by AlexReynolds 01 November | 23:32

okay, in what algebra? or group? how about just for simplicity's sake, i point out sin(x)/x as x goes to zero? which doesn't quite answer your prompt perfectly, but it's zero in the bottom and it's not zero as an answer (although weirdly, it's also zero in the top), so how about it?
besides, we both know that's not what we're talking about. we're talking about how it's not a meaningless question; i didn't explicitly make that clear but i think it should be obvious i'm not looking for an algebra fight.
anyway, it should be pointed out that as long as one satisfies four requirements -- identity, inverse, commutivity, and association, one can define a group, so i imagine we can have algebras where an operation like dividing by zero is feasible.

although probably not very useful.

Additionally, please explain how we'll show empirically that we are in a toroidal space when we cannot see beyond the Hubble radius. I had a brief

the properties of toroidal space would be exhibited in long range phenomenon, it is true. but that is only at one energy scale. the shape of the space could also be demonstrated on short ranges at high energy scales. so, basically, the answer here is, we hand this over to the RHIC guys (or rather, whoever can build something a few steps up therefrom -- i don't know the scale but i doubt we're probing it yet) and say, 'hey, when you're watching the particle tracks, do they go in funny directions? okay i guess it's a toroid then.'
alternatively, we can hand this one off to the cosmologists, who'll look at motion of things in the intermediate regime -- which is basically the largest regime we can look at -- and say, well, this cluster's moving wonky, and its track is actually rectilinear in a space with these properties and dot dot dot.
all the time. people are all the time publishing papers where they make their claim that we live in some blah blah blah space. we're not yet at the point that we can say with definitiveness what that space is, but it should absolutely be an answerable question.

email conversation awhile back with Princeton's J. Richard Gott about this and so far we have no

huh i don't give a shit about name dropping. i go to classes taught by people who wrote the book on this stuff -- literally, so it really doesn't matter who you've talked to. i'm right about the diff. geometry regardless of princeton or the east timor school of wig manufacture or whatever.
as we would all know if we sat in my lsat class monday night, an appeal to authority is not the same as proof. i'd be very interested in a proof as to how we could not determine the properties of the space from local considerations.

evidence for being able to see "through" the universe to the other side, to see the "backs of our heads", so to speak, and from the current estimated rate of expansion, it doesn't seem likely that we ever could, or will.

there are plenty of other reasons for thinking we live in certain kinds of universes. i'd honestly reccommend reading some of the literature on this if you're interested, because i can't speak with sufficient specificity to be worth listening to. cf. supra for brief description.

Asking what the universe expands into is a meaningless question, because the question has no meaning.
posted by AlexReynolds 01 November | 23:38

bushwa. the question is more like asking, 'why is an orange heavier than a cat,' but it's certainly not meaningless. i think it's an excellent instantiation of an abstract concept in geometry.

somebody draw a circle in the ground and tie alex's and my left arms together! we settle this the texan way.

somebody draw a circle in the ground and tie alex's and my left arms together! we settle this the texan way.

crapo 2x post. also: consider this paradox for an open/infinite/HOMOGENOUS universe, famously posed by e. allen poe -- if the universe is infinite and static and homogenous, wouldn't there be a star on every sight line? therefore, the night sky should be white.

of course, universe CLEARLY not static. somewhat seems to be isotropic on large scale. but hey it's pretty good for a guy who writes the novels, right?

NERD FIGHT!

Kidding. I have no idea what you said sam but it sounded mighty impressive.

that means I HAVE FAILED.

i shall be clear in the future.


but alex ran away first therefore i'm probably taller.