does our universe have a border?

>>8848094
how is pic related? are there anime girls waiting on the edge of the universe? if so hurry up and build an FTL drive so i can fuck your waifu

File: 1476846155548.jpg (58KB, 604x453px) Image search: [Google]

58KB, 604x453px

Heres my hypothesis

Everybody who likes, has a profile picture or something related to this from Makise Kurisu is:

1. A pretentious smug faggot with a superiority complex
2. Somebody who thinks is smarter than everybody else he comes in contact with and wants to let everybody know because ''Lol XD I indentify with le super genius girl''

Its been 6 months and I think I am correct. Every makise faggot I've met fits on either one of those categories.

>>8848097
no, there are just genius physicist anime girls

>>8848113
either way they're getting this dick, beam me up scotty i'm coming for your hotties

>>8848097
>twf someone cucks you outside your lightcone

>>8848094
In a sense, yes, and in a sense, no. When you're looking at the distant stars, what you're seeing is the light that was emitted from those stars billions of years ago that finally reached the Earth. In this sense, the "observable universe" has a "temporal edge" in that if you look out far enough, all you'll be able to make out is the cosmic background radiation from the big bang.
If you're talking about the capital-U Universe consisting of not only the observable universe but also the stuff "outside" of it, even though in a technical sense the stuff "outside" the observable universe hasn't happened yet (ignoring relativistic technicalities), then measurements suggest that it's mostly similar to R^3, and is thus infinite. Or it's just really, really big. There's not really a way to tell between the two for sure, since no matter how much we stake out, it could just be bigger than that. Note that being finite does not necessarily imply that it has a boundary. It could be that once you go out far enough you arrive back where you started, like a 3D version of the Asteroids game. It could also be a more complicated 3-Manifold, such as the surface of a 4-dimensional hyper-sphere. But again, measurements suggest that it's not only flat, but doesn't repeat, and we haven't seen an edge. In other words, as far as manifolds go, it's probably similar to R^3. Actually, I recall that there's a way to characterize the space-time relationship as a 4-Manifold where time is taken as a fourth dimension, and that's definitely not flat. That's what people mean when they say gravity is just the curvature of space-time. But that's a different story for another time.

>>8849479
it is hard for me to imagine the universe like R^3 since in reality doesn't exist infinite things. For example after big-bang it may be not as big as now.

So the more reasonable answer for me is a compact manifold without boundary. So there may exist a point where you arrive back when you follow the same direction.

>finite implies compact
HMMM

>>8848094
Finite does not mean it has an edge.

>>8849634
I know it