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i dont think our universe really have an edge...
if we look on it practically as we know the universe is expanding and the edge of the universe depends on that expansion we can say that the edge of the universe is continuously changing and also the edge depends upon the shape of space matrix all around but still as we know dark energy is responsible for expansion so it depends on the behaviour of dark energy as if it obeys the law of conservation of energy then the rate of expansion of the universe would be exactly same everywhere and hence every part would expand in a symmetrical way now if we consider the whole universe as a large system with conserved energy then its orignal shape must be spherical and hence we can say the universe is expanding in spherical symmetry so it will have no edge
i kinda have to wonder what defines an "edge" for the universe
if multiverse' exist then no universe may have an edge
If considering the universe a sphere in totality,then i guess the universe wouldnt have an edge.Just like earth....And any mass in space tries to occupy minimum volume,so i guess the universe is pretty much a sphere.
Its not a perfect analogy though, more of a metaphor I think. If the universe was a true sphere then traveling in one direction I would eventually get back to where I started, which I don't believe is the case.
the answer to this question would depend on how you define "universe". if by "universe" u mean the observable universe , then the answer would be a yes . the observable universe is quite understandably expanding (or its edge is moving away) at the speed of light. if you are talking about the complete "universe" (which is not very well defined) , recent experiments have shown that its topography is more or less flat(and which implies it is endlessly extending). moreover, you may involve the concept of multiverses which will make the topic even less specific and less answerable. so, all in all it depends on what you mean by the term "universe"
paarth what do we mean by complete universe? is it a multiverse?
that's what i said. it is not defined and, probably, will never be. so for all practical purposes ( which won't be very much practical in the present or the near future)we can use the observable universe which, yes, does have an edge expanding at the speed of light.
universe have an edge as its just asystem having limited energy.
@009infinity how are you defining 'edge?'
it is expanding till now but its edge is expanding with a constant rate.
If universe began from a point and immediately after big-bang began to expand and is expanding, it must have an edge.. Saying that something which 'doesn't have edge' is expanding doesn't make sense at all.. So. if you say the universe is expanding you must say that it has an edge which is expanding along with its expansion! But that's too classical and simple explanation.. maybe it isn't that simple.. but that's what i think!
@009 you mean the edge of the observable universe, the light horizon, not the actual universe itself.
@ujjwal that misconception comes from thinking that the universe is expanding into empty space, but all space (empty or not) is within the universe.
its ur misconception @CliffSedge as energy creates space and time and definetly space is within the universe.
So, how is the universe expanding? Expanding refers to gradual increase in size.. If it doesn't have a size, how can its size increase?
let me give you a hint our universe have boundaries proved by holographic principle, so this boundary can store information on its walls
@009 how is that my misconception? You didn't say anything that is in disagreement with what I said.
@rv, that is still not a physical boundary. These 'walls' you speak of don't exist anywhere.
the way I was told to imagine it is a balloon. imagine the 2d surface of the baloon is our 3d space. as the balloon is inflated that 2d surface expands, but still has no edge
@ujjwal "So, how is the universe expanding? Expanding refers to gradual increase in size.. If it doesn't have a size, how can its size increase?" The expansion is the increase in distance between galaxies. The Big Bang did not occur at a point and then a small universe got bigger. The Big Bang occurred everywhere at the same time. The universe is either infinite or finite (this is unknown, my guess is finite). What ever its finitude at the time of the Big Bang, it is the same now. Expansion occurs everywhere equally.
@JamesWolf yes, that can help visualize details of the expansion, but since people can't visualize expanding 4-dimensional spacetime, it can be a misleading analogy.
Its a really hard one to visualise. Like trying to imagine viewing all of 4d space at once. rather than just 3d spaces with slices of the 4th dimension (time).
this is a fact that our universe have boundaries. on which it can store the information the most basic physics principle that information can never be lost e.g., if a star dies it must leave some information in the universe as a residue, where does this information goes is the boundaries of the universe so whats ur ans now?
My answer is that I dont understand the holographic principle well enough to comment.
bloody good drawing considering the shocking software on here
its some what like that time is 4th dimension
@rvgupta I do understand the holographic principle, but you are still imagining that there is a physical wall somewhere that encodes information on a 2D surface. I recommend studying the topic further. Leonard Suskind has some good explanations. It is related to black hole physics as well, so spend some time with that.
"if a star dies it must leave some information in the universe as a residue, where does this information goes is the boundaries of the universe" When a start dies, its 'information' is in the form of the matter that it was made of, that matter still resides in the space the star was in.
if u people r talking about expansion then let me tell u that it depends on the latest theory INFLATION which predicts that universe expansion rate is continuously increasing even faster than the speed of light so its impossible to say that whether our universe is finite or infinite
That is NOT the theory of inflation
so what do u think
Some casual reading: http://io9.com/5818008/the-universe-probably-isnt-a-giant-hologram-after-all
@rvgupta (leaving aside your rude tone for now) "if u people r talking about expansion then let me tell u that it depends on the latest theory INFLATION which predicts that universe expansion rate is continuously increasing even faster than the speed of light so its impossible to say that whether our universe is finite or infinite" This is false. Inflation theory isn't a prediction, it is a model of cosmic dynamics shortly after BB. The increase in expansion rate now is unrelated. No matter travels faster than light, but the space between matter can expand at any rate. You are correct that it is not yet known whether the universe is finite or infinite, but regardless of which, there is still no boundary.
Some more casual reading: http://www.cfa.harvard.edu/seuforum/faq.htm#s1
so what about the information lost
What does "information" refer to? @rvgupta
what information loss? when a star explodes the information is taken from all the parts that fly off isnt it? if time is reversed you get the star back. no information is lost?
it is the most basic principle of physics that information can never be lost so it must be somewhere based on this susskind said that our universe must have boundaries to store this information, even stephen hawkink said that it should be right
I dont think you understand it, (im not saying i do). explain to me where the information is lost? Hawking showed that information was not lost in a black hole, since a black hole evaporates?
what do u think about parallel universe this theory is useless without boundaries
Yeah, I'm not seeing the information loss either. Are you talking about black holes?
i think information is not lost till we exist to precieve it
I don't think you understand 'parallel universes' or multiverse theory either, rvgupta..
@CliffSedge can u explain
the old does a bear pellet in the woods theory infinity? :P
@009infinity 'information' (in physics) is not the same as knowledge. Information is due to signals (relative motion or other interactions of matter and energy).
I just understood that i understand nothing! Carry on Young Scientists!!
The multiverse is not like universes physically stacked on top of each other as if they were sheets of paper. The multiverse is a sum-over-histories of all the possible interactions that could occur in given instances.
@ujjwal congratulations, you are at least as wise as Socrates! :-)
As much as I would love to continue this discussion all day, I have to leave for work in like 5 minutes, so we can pick this up some other time if you are still interested.
information will exist before time is over am i right now
I don't know what that means, @009infinity "before time is over" ??
cliff u r now talking about parallel universe not multiverse
The multiverse *is* parallel universes. It's the same thing, @rvgupta
@CliffSedge there r two sence of it that inoformation will exist in universe till time exist (before big crunch)& second its too long discussion to over it
"@ujjwal congratulations, you are at least as wise as Socrates! :-)" The oracle would like you :)
parallel universes are supported by string theory so dont say that they r same
@009infinity "there r two sence of it that inoformation will exist in universe till time exist (before big crunch)& second its too long discussion to over it" There is no 'Big Crunch.' The universe will likely go on expanding forever and time will not end.
Yes, @rvgupta I understand the inflationary model. It does not support anything you are saying about boundaries. Regardless of what String Theory (a theory that makes no predictions, explains nothing, and has not been tested) says about parallel universes, that has nothing to do with parallel universes and the multiverse meaning the same thing. You are profoundly confused; please do some more studying on the matter.
is there any evidience for that @CliffSedge
The universe can be thought of as a sphere expanding in all directions with the passage of time. Because of inflation, the universe was able to expand faster than the speed of light. When we look out into the universe you would think that we would be able to find an edge, but we can't because the universe is bigger than the range in which we can see. Because light is finite we can only see so far out into the universe, the reason why we can't past this is because light hasn't had enough time to reach us yet. Then there are other ideas about the universe being a multiverse and pocket universes, but that's another story.
http://en.wikipedia.org/wiki/Dark_flow is an interesting mystery regarding the "uniformity" created during the inflation period.
cliff do u want to say that im a fool
but i also have who will prove first u or i @CliffSedge
I'm sorry, I provided a bad link to a David Deutch article. I still recommend his book, The Beginning of Infinity.
''that is created must be destroyed" here is the proof
I dont think cliff is calling you a fool. i just dont think we understand these theories. Its easy to just regurgitate what good scientists say but until we get in there and start understanding the equations we really dont know what were talking about
@rvgupta , I am not interested in discussing whatever words you are trying to put in my mouth.
@009infinity "''that is created must be destroyed" here is the proof" That is a pithy statement without meaning.
so is there any conclusion
Conclusion (based on best current science): The universe is finite and without boundary.
"Does our universe have an edge? if yes. Explain" No
would u people like to discuss it tomorrow
Sure though i cant really add much
i will surely give u some astonishing proofs
i m ready for genune ones ;)
so i am ready to give
To count as "astonishing proofs' I will need to see observational data confirmed by at least one other independent source, references to peer-reviewed journals, and any theoretical explanations must be annotated with statements of falsifiability, and relevant criticism from professional scientists. Good luck!
setting the bar low then... :P
@JamesWolf Yes, but ya' know, this is only OpenStudy, nothing serious.
what time do u decide to discuss then
I don't know. I log on once-in-a-while when I'm not busy with other stuff. If I don't go out later after work, then I might be back on around 02:00 GMT tomorrow.
r u ready 2 hours before this time
good question but answer is no
no still not
scroll up and go through the link
i have read that all and they can be true but some theories like M theory predicts that our universe is not only the universe and it can have edge however this theory is still unproven
I don't believe in M and String theory. all of that are hocus pocus. It is more toward mathematics and philosophy or pseudoscience rather than physics. If you can't experiment with it, it just a beautiful guess.
There is one feature I notice that is generally missing in M and String Theories. It's a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty — a kind of leaning over backwards. For example, if you're doing an experiment, you should report everything that you think might make it invalid — not only what you think is right about it; other causes that could possibly explain your results; and things you thought of that you've eliminated by some other experiment, and how they worked — to make sure the other fellow can tell they have been eliminated. Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can — if you know anything at all wrong, or possibly wrong — to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition. In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.
That's why I dislike someone who came with a theory that claim something so big yet so little prove. When asked the prove, they say "Oh just believe in me. Because this theory is SOOO beautiful." It's like a religion really. No wonder people have less honour about physics now. M and String theory are not science yet they promote it as is.
It is crazy, nonsense, and the wrong direction for physics. It is new version of medieval theology, and I wish to keep string theorists out of physics.
The entire mainstream modern physics band waggon has ignored REAL PHYSICSTS for simplicity and understanding what is known for sure, and has gone off in the other direction (magical unexplainable religion) and built up a 10 dimensional superstring model whose conveniently ‘explained’ Calabi-Yau compactification of the unseen 6 dimensions can take 10500 different forms (conveniently explained away as a ‘landscape’ of unobservable parallel universes, from which ours is picked out using the anthropic principle that because we exist, the values of fundamental parameters we observe must be such that they allow our existence).
… I do feel strongly that this is nonsense! … I think all this superstring stuff is crazy and is in the wrong direction. … I don’t like it that they’re not calculating anything. I don’t like that they don’t check their ideas. I don’t like that for anything that disagrees with an experiment, they cook up an explanation … All these numbers [particle masses, etc.] … have no explanations in these string theories – absolutely none!’
Besides, what is really there in string is not mathematical beauty, rather, it is mathematical ugliness and scientific failure.
Moreover, string theory is NOT even wrong because it does not provide any testable predictions. it has nothing statistical to back it up therefore it is not a valid scientific theory, it is non falsifiable as it currently stands, thus it is not even wrong, it's closer to philosophy atm; that to my mind is uncontestable; if you can show me evidence of string theory then I'll change my mind. Thus for someone to make an argument based upon M theory is just stupid.
In conclusion: String and M theories are in the same category with intelligent design, religion, philosophy. They are in a basket or branch of CRAZY department.
the universe has an edge like a cloud , the universe is where all the energy and matter exist, at the 'edge' is where there concentration of energy and matter diminishes to zero this is a fuzzy boundary
it somewhat depends on the shape of the universe whether its shape is spherical and like slices of breads proposed by some scientists
you can be right
@twitter , I love you.
Hey man love you too. screw string theory. It degrades physics.