Is there any limit for the size of our universe? what is a black hole?

Question

are there limits for our universe? can we have a starting and a end point for it? or can we cross ouir universe and go to the next universe or what ever comes next?or is universe somthing similar to the round earth no starting and ending point? any ways does the black hole form as a part of a door to the next universe or somthing like that? Can we cross the black hole?

Answer 1

There are no known limits to the universe as we know it, except that it is theoretically limited to only 11 dimensions by certain theories.

As for black holes, once you or anything (light, radiation, and matter) are inside of one, you can never escape, but nobody knows what sort of reality (if any) exists inside the event horizon of a black hole, so sorry that is impossible to answer.

Answer 2

Well, there is technically a limit to the universe. It all started with the big bang. No one knows where it came from but we usually just think of it as ex nihilo, or "out of nothing". So after the big bang, all of the universe expanded, and it hasn't stopped yet! Infact, there are three fates of the universe due to this expansions (called the hubble constant). Here is a slide show that will help,  it is the first one: http://www.google.com/search?hl=en&rls=c...

You will see that the fate of the universe is all dependent on the density parameter, represented by omega. It depends on the ratio between the density and the critical density. If omega is less than 1, then it will result in the big chill. If omega is equal to 1 it will result in a flat universe. And if it is bigger than 1, it will result in the big crunch. So there are possible limits. However right now, there is a limit. The universe is about 93 billion light years across. So yes, there is a limit. however, you might ask if the universe is only 13 billion years old, and nothing can travel faster than the speed of light, how could it be 93 billion light years across? Well, because Einstein said so. His theory of general relativity says that space can expand with no intrinsic limit on its rate. So basically space can expand as fast as it wants to. Now for black holes. Black holes are usually formed either when a star goes supernova and collapses, or when two neutron stars collide. Black holes have two defining features. The event horizon, and the singularity. The event horizon is the boundary in which nothing, including light, can escape. Once you go past, you're gone. Then eventually you will be sucked into the singularity. This is a point of infinite gravity. THis is kind of the final resting place of what goes in. However, it can come out as what we know as Hawking radiation (after stephen hawking). Hawking radiation is basically pairs of particles that form on the event horizon. Once you go inside the black hole. You get squished and form hawking radiation, and leave in pairs. One particle will form outside of the event horizon, and therfore can leave, and one forms on the inside of the event horizon, and therefore, gets pulled back in. bummer huh? This is why black holes take SO LONG to evaporate. And did you know that in the center of most galaxies including our own milky way, there is a super massive black hole? It is quite remarkable. Well, if you actually read all of this, hopefully I helped. And also, I know I am just being a bit insecure but I am only 15 with no formal eduaction in astronomy (like in school), so could you tell me what you think? I know, I know, you don't have to. Anyway, hope this helped.

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Answer 3

the universe is endless. it will never cease on expanding. black holes are a result of supernovas of stars more than 100x the sun's mass. the material inside them are so dense, they have so high gravitational pull, they suck up everything near them and even suck up themselves. even light cannot escape a black hole, and if you get sucked in, your body will be turned into a long thread of spaghetti and you'll be cut into tiny pieces. You can cross to the other side, but your lucky if you get there ALIVE.

Answer 4

since ours is an accelerating i.e open universe there is no end to it. Black holes are the end result of stellar evolution of stars 3 times more massive than the sun. the gravitational pull of a black hole is infinite which is why light cannot escape it. therefore any falling object that crosses the event horizon will be torn apart by the difference in the gravitational force  exerted on its bottom and on its top.