What exists outside the universe?

[whateverfloats]

The20

baka_evalu_chan

My brain hurts D:

Maybe the universe expands because there is nothing containing the force of it expanding. It's like when you suck the air out of a can. The can implodes because of the vacuum. Think of this example but instead of a can, the universe expanding into nothingness because of no force being there to make a balance.

Then why was the universe a singularity in the beginning?

Yeah, that's not it. There is no vacuum pulling on the universe because there is no space outside the universe.

[The Fallout Engineer]

... According to scientists, the existence of the universe will end with the Big Crunch. That is, the opposite of the Big Bang, where the universe will contract into a speck of immense energy. But, if the universe is "expanding", how will it reverse the process? I mean, there is nothing to cause the initial contraction so how does the Big Crunch occur..?

[Elden Andel]

The big crunch is just one idea on how the universe will end, there are others. I like the idea were we just can't prosive the entire universe at the same, which could be because of the 4th plane, but I would have no idea. I have heard that taht the universe might have started when two "verse" membranes colided, but I still haven't had time to look into that one. Now I have a question, black holes dip deeply into the spacetime, so can something with enought mass/power/something rip/puncute/some term that can't be explained 3-D, if not where does the energy/mass go?

[Layra-chan]

Elden Andel

Now I have a question, black holes dip deeply into the spacetime, so can something with enought mass/power/something rip/puncute/some term that can't be explained 3-D, if not where does the energy/mass go?

Short answer: no. Black holes don't dip into spacetime (dear god I hate that rubber sheet analogy. Frikken piece of utter crock.). Spacetime doesn't even really move at all. As a collection of points, spacetime with a black hole in it looks exactly like spacetime without a black hole in it.
What happens is that local directions become screwy.

Picture a signpost at every point in spacetime; on this signpost are the directions: forward, backward, left, right, up, down, future, and past; also, each direction has a length attached: "So many kilometers until the next signpost in this direction". An object in spacetime naturally obeys the signpost of the point that it's at, going in the designated forward direction and the designated future direction at the appropriate speed, which depends on the lengths attached to those directions by the signpost.

In spacetime without a black hole, all the directions are perfectly aligned from point to point; if you go forward according to one signpost, you end up going forward according to the signposts at all the other points. Moreover, the length associated with forward according to the signpost at any point is the same as the length associated with forward according to the signpost at any other post.
This is inertia, in which objects continue in the same direction (since all the signposts are aligned) at the same velocity (since all the lengths are the same).

Gravity is a subtle distortion of the signposts, so that at a given point, forward is bent ever so slightly in the direction of the gravity source, and the length associated with the future is dilated slightly.
The distortion is subtle, so that for two points nearby, their signposts are almost identical, but there will be a slight difference. As you approach the gravity source itself, the distortion becomes greater and greater. Note that the actual points haven't changed, only the signposts.
Now the object, still obeying the signposts, moves toward the gravity source, since forward at each point bends slightly toward the gravity source, and accelerates toward the gravity source, since the length associated with the future is changed slightly. Hence, gravity.

The difference between a black hole and any other source of gravity is that since in a black hole, all the matter and energy is in the center, you can get a lot closer to the center of the gravity source and thus you get to experience a much greater level of signpost distortion.

But spacetime hasn't changed. The signposts at each point in spacetime may become totally screwed up, but spacetime remains the same.
Can the signposts "rip"? Well, the signpost at the center of a black hole doesn't really point very well since things at the center of a (non-rotating) black hole can't go anywhere. Points where the signposts go bad, i.e. where two of the directions overlap or where the length associated with some direction goes to 0 or infinity, are called singularities. The center of a (non-rotating) black hole is a singularity. For a rotating black hole, the singularity is ring-shaped.
So yes, the signposts can behave badly, but as they aren't locations but directions, there's no fear of energy loss or anything of the sort.

[z9z9z9z9z]

Don't let anyone BS you. No human being knows what's outside the universe, no more than you do.

[VorpalNeko]

Elden Andel

Now I have a question, black holes dip deeply into the spacetime, so can something with enought mass/power/something rip/puncute/some term that can't be explained 3-D, if not where does the energy/mass go?

Yes; an ordinary Schwarzschild black hole is already geodesically incomplete, meaning a test particle can have a trajectory that abruptly 'ends' in finite time (at the singularity). The energy doesn't go anywhere, though: it's conserved in the sense that the event doesn't decrease the mass of the hole. If one were feeling a bit whimsical, one could say that a black hole is a mass-to-gravity converter (or in gtr-speak, Ricci-to-Weyl curvature).

Note: Layra-chan seems to interpret the question a bit differently. I don't think I like her analogy any better than the rubber one, but I understand her intended point, that everywhere is a part of spacetime and gravity just rearranges it, she's perfectly correct. Which is actually a bit closer to the original point of this thread: "outside spacetime" is probably an incoherent concept, because, well, any such thing literally has no place and occurs at no time.

A caveat: in GTR, it's not uncommon to label regions separated by a Cauchy horizon as different 'universes' (cf. rotating black holes), but they're part of a single spacetime, so again it's strictly speaking improper.

[VorpalNeko]

z9z9z9z9z

Don't let anyone BS you. No human being knows what's outside the universe, no more than you do.

Let's put it like this: if someone were to say to you that you know nothing about married bachelors, a very reasonable reply is to say they're just not making any sense. "Outside the universe" similarly makes no sense whatsoever (unless we interpret it as having some implicit qualifier, like 'observable'). There might be some way to interpret "outside spacetime" (as the OP was more concerned about) in a coherent manner, but I don't really see one.

[Layra-chan]

Hmm. I've always viewed "ripped" as an issue of closure, not geodesic completeness, and I'm guessing that's how most people interpret it. A line segment isn't geodesically complete, but it isn't "ripped" in the usual sense.

[VorpalNeko]

You can, however, encounter endpoints--intuitively, a line segment can be viewed as a piece of a line that's been torn away. This is a bit clearer in more dimensions: if you puncture an infinite, planar piece of paper or give it a small tear, then it's now incomplete in the sense that if you're an ant walking on it, you can encounter edges (and presumably walk off them). Since the context of the question is leaving spacetime, it seems appropriate enough to interpret 'puncture/rip' as introducing some sort of fundamental incompleteness of paths.

I suppose that's part of the trouble of using analogies in the first place: everyone's got a different picture of what's a natural or intuitive way of thinking about something. (The other part, of course, is that it takes substantial familiarity to know where the analogy becomes inappropriate.)

[kami two]

outside of the universe.. well you might first wana find out all about whats inside the universe. the probability of other human beings or high developed creatures like us is very high. you might be interested in their creations, culture, blahblah. the possibilities inside the universe are far beyond you can imagine. so start being creative and think about new stuff you wouldnt even imagine. start pasting things together and make a huge thing that did never existed before. because you created it.
if beyond the universe is like without time it would be a world containing every single possibility inside the universe. And YOU are about to choose which possibilitie youre going to be in the next time till you die. so use that time to get to possibilities you live for.

[Pwale]

I was always led to believe that the universe is expanding in on itself. Which makes sense if you've ever seen an infinity strip-just picture that as existing in every possible dimension and then understand that there's an infinite (or as good as) number of dimensions we can't possibly comprehend-including somewhere in that lot a dimension of growth. That's always how I figured it out in my head to avoid troubles-I realize it's a frightfully imperfect metaphor but since no one really understands how this works I'm happy with it.

...
...And I realize this is trite, but authors like Asimov and Douglas Adams always helped me to kind of understand the more complicated stuff. Y'know, just to avoid headaches. Though I really liked how Adams treated the "universe expanding" conundrum in the 2nd book. (Shrugs)

What I always found most interesting is that "outside the universe" and "before the universe" is so far outside the human comprehension is that it's not even possible for us to have the language to describe it because any language we created for that purpose would exist and therefor be a paradox. I always liked that.

[False Dichotomy]

logan the god of candy

outside of the universe there is most plausibly either a multiverse or nothing

You're forgetting the omni-verse talk2hand

[The Zodikosis]

It is not known for sure. Everything posted in this thread is merely speculation. We have no real evidence for what exists outside our universe, or if the universe ever really ends, since it is supposed to be ever-expanding.

[ethraa]

nothing XD