Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Michael Zuk on 14/12/2010 12:30:04
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Michael Zuk asked the Naked Scientists:
Hello all!
It doesn't seem possible, that "SPACE" (the dark part) is infinite. There's always a start and finish, a beginning and end, birth and death. Is the an edge (or start) to "space"?
Thank you so much! Looking forward to your response. Have a great day!
Thank you.
Sincerely,
Michael Zuk
What do you think?
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It seems reasonably clear that our universe has a start and probably will have a finish (although that may be very indistinct and asymptotic) but it is also clear that we will never be able to see the edges.
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If we believe in the "Big Bang", then all matter in the Universe started in one place about 13.7 billion years ago.
An event happened causing a rapid expansion of matter and energy into the surrounding area.
So, then the "edge" of the matter in the universe, and potentially space would be the extent to which matter and energy has arrived over the period of 14 billion years.
Is it expanding into space, or is it the space itself that is expanding?
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wouldn't traveling near C as time slows down define some sort of "edge"?
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Clifford - not so sure about your description; the big bang happened everywhere - not at a place within space. there was no surrounding splace to expand into - space itself was expanding or inflating.
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Assuming acceptance of the Big Bang, which in our present state of knowledge seems a reasonable thing to do, our Universe had a beginning; it is therefore finite (in our F of R), although it may be unbounded. This, as Clifford said, implies that it has an edge.
What, if anything, is beyond that edge is more of a matter for conjecture. I struggle with the "something from nothing" idea, so I suspect that something existed prior to the BB. Also, I have grave doubts about anything that involves infinite regression, so I am inclined to think that our Universe is embedded in an infinite something, which, to preserve clarity of terminology, I refer to as the Cosmos.
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The universe does not contain an edge, or a boundary. For it to have such a thing, it would need to be a boundary between something, and something else, and since nothing exists outside the universe, then the universe by deduction cannot have a boundary.
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Our universe may have a 'boundary' (for the want of a better word), in that matter resulting from the Big Bang is continuing to expand and therefore there must be a point beyond which it has not reached yet. But beyond that 'boundary' there is empty space, into which it will expand, and that empty space is boundless, infinite.
For me, the description of our universe is one of matter in varying degrees of concentration. Bodies, such as Mars, our Moon and asteroids are areas of the highest concentration. Other bodies, such as Jupiter and the stars are areas of lower concentration and the regions between those high and medium areas of concentration are the lowest concentration, but entirely empty. Beyond the universe is true empty space.
I do think that 'infinity' and 'nothing' are concepts which we have great difficulty in coming to terms with.
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Our universe may have a 'boundary' (for the want of a better word), in that matter resulting from the Big Bang is continuing to expand and therefore there must be a point beyond which it has not reached yet. But beyond that 'boundary' there is empty space, into which it will expand, and that empty space is boundless, infinite.
Spacetime does not expand into already existing space. There is nothing beyond our universe. Everything which happens in our universe is self-contained. And there does not exist a boundary either - mathematical discipline into our universe does not yield a boundary, which is an approach itself of unifying the large and the small called quantum cosmology http://everythingforever.com/hawking.htm .
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Here is a page from a NASA expert who also states there is no edge to the universe, http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/961202c.html
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..With the balloon analogy I detest :)
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..... There is nothing beyond our universe.....
Precisely my point.
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..... There is nothing beyond our universe.....
Precisely my point.
so einstein & heisenberg no longer apply?
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There is nothing beyond our universe.
Your apparent certainty suggests one of three things:
1. You have been there.
2. You are guessing.
3. you have been reading Donald Hamilton.
Come clean. [;D]
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Nobody knows either way. There are scientific instruments using indirect analysis of using the spectrum of light and the change of the spectrum over time.
It stands to reason that there is a scientific explanation that causes the differences.
Since the universe is so huge, to define an edge is like counting the number of grains of sand our earth is made of. Just because you can not see something, should that be a conclusion that it is not there?
The consensus leans to the point that there is no edge to the universe.
If it is discovered that there is, do you think anyone would listen, without first hand proof?
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Assuming acceptance of the Big Bang, which in our present state of knowledge seems a reasonable thing to do, our Universe had a beginning; it is therefore finite (in our F of R), although it may be unbounded.
This isn't necessarily the case. The universe may have been infinitely big at its beginning and also infinitely dense. It could then expand, remaining infinite. That's a lot of infinities flying around, but when you're dealing with concepts like the entire universe, they might be physically meaningful.
I agree with QuantumClue, though. The universe most likely can't have an edge, since that would imply there's something beyond that edge. The real question is whether the universe is open or closed. Open means that it's basically infinite, so that you can keep going in one direction and never return to your starting point. Closed means that if you keep going in one direction, you will return to your starting point (like in the dreaded balloon analogy). Even if the universe is closed, it doesn't have an edge, just as there is no edge to the balloon's surface. This is a place where the balloon analogy breaks down, since there is space surrounding the balloon, but there isn't space surrounding the universe, since the universe contains all space.
It's impossible to state that the universe "cannot" have an edge with 100% certainty, but that's only because science can't categorically disprove something that can't be observed. There is, however, no good reason to think it has an edge, and no theory that appears to describe a universe with an edge. Universes without edges, on the other hand match well with what we understand from general relativity about the possible shapes of the universe.
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There is nothing beyond our universe.
Your apparent certainty suggests one of three things:
1. You have been there.
2. You are guessing.
3. you have been reading Donald Hamilton.
Come clean. [;D]
You're right, I do have a certain degree of certainty about my claims. It is not however a baseless imaginative fabrication of wishful thinking on my behalf.
For those of us who believe in Relavity, also believe in its postulations, and relativity strictly says that nothing exists outside the realm of our universe - this is what one might call a mathematical certainty.
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..... There is nothing beyond our universe.....
Precisely my point.
Then you would seem to be implying that speaking about space, we are referring to something which is nothing... This would be incorrect. Space in our terminology is in fact something, empty space is not actually void and empty of anything. It's a bubbling couldron of virtual particles. Outside the universe, there is no word which can describe this ''nothingness'' - it simply has no description, a non-reality. It is neither space, nor time - energy or even matter. No volume, nothing.
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..... There is nothing beyond our universe.....
Precisely my point.
Then you would seem to be implying that speaking about space, we are referring to something which is nothing... This would be incorrect. Space in our terminology is in fact something, empty space is not actually void and empty of anything. It's a bubbling couldron of virtual particles. Outside the universe, there is no word which can describe this ''nothingness'' - it simply has no description, a non-reality. It is neither space, nor time - energy or even matter. No volume, nothing.
Agreed. The 'empty space' between the stars planets etc in our universe is not exactly 'empty' at all, but beyond our universe is nothing. The problem, as I stated before, is that our conception of 'nothing' may not quite fit the true meaning of the word.
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Agreed. The 'empty space' between the stars planets etc in our universe is not exactly 'empty' at all, but beyond our universe is nothing. The problem, as I stated before, is that our conception of 'nothing' may not quite fit the true meaning of the word.
Or beyond, for that matter.
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The problem, as I stated before, is that our conception of 'nothing' may not quite fit the true meaning of the word.
I agree that our understanding of “nothing” may be inadequate. Trying to come to grips with the concept of nothing, I used a visualisation exercise with several non-scientists. This is how it went.
For the sake of the exercise, we will assume the correctness of a number of theoretical positions: First, the Big Bang itself; secondly, that before the Big Bang, there was nothing and, thirdly, that inflation caused the infant universe to expand extremely quickly. Now for the mental image: The Universe appears, out of nothing. It inflates rapidly to the size of a beach ball. Freeze the scene at this point and describe what you see in your mind’s eye. Do not bother too much with the appearance of the Universe, it is the image of “nothingness” that is of interest.
All the people I have asked to undertake this exercise have described a sphere of light, surrounded by blackness which extends (some qualify this with such words as “presumably”) to infinity in every direction. There is a second part to the exercise. Now imagine two universes coming into existence simultaneously. Freeze the action at the same point, and describe what you see. The picture that emerges from those who have undertaken the exercise is of two spheres of light, separated by blackness, and surrounded by infinite blackness. Two points need to be addressed here. One is: does the second mental image really describe two objects with nothing between them? The other must be: is this what nothing looks like?
If we talk of two runners, for example, finishing a race with nothing between them, we mean they are so close together that it is almost impossible to separate them. Obviously, this is a figurative use of the term, because, unless they are actually in physical contact at all possible points, which is very unlikely, there will be at least a small amount of space between them. Strictly, then, can we talk of two things having nothing between them if there is any sort of gap between them? We might argue that there is nothing in that gap, but the gap itself must be space, and space, as relativity tells us, is something in its own right. This must lead us to reason that if our two imagined universes have nothing between them, then they must be contiguous, with maximum surface contact. This must prompt us to question the nature of the nothingness surrounding both the pair of universes, and the earlier single universe. If we cannot have a space between them with nothing in it and justifiably call this “nothing”; how can we have space around our universe, or universes, and call that “nothing”. This brings us to the second question: “is this what nothing looks like?” The answer must be “no”, because nothing cannot look like anything. Where does this leave us? I believe it leaves us having to acknowledge that we cannot actually visualise nothing. Many popular science books assure us (and rightly so) that we cannot visualise a fourth dimension of space, let alone the ten, or more, dimensions required by string theory, because we have no experience upon which to base such a visualisation. In the same way, I suspect that our life experience prevents us from forming a mental picture of nothing, because we have never experienced it, either first hand, or through someone else’s description of it. Our nearest experience is of “empty” space, so when we try to visualise nothingness, we use empty space, as a convenient substitute. If space has ever been a suitable substitute image for nothingness, it certainly is not now, because, according to quantum theory it is far from empty. Of course, there may be mystics somewhere who can visualise “nothing”. Perhaps Fred Alan Wolf could find us a yogi who could do this. The possibility must not be ruled out, but for the vast majority of us the fourth spatial dimension and “nothing”, together with the moment of creation of the Universe, will probably remain concepts we can acknowledge only intellectually, but never actually visualise.
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There's a very important difference between visualizing nothing and visualizing 4,5,6,... dimensions, at least from the point of view of a physicist. Dimensions follow geometric rules that are extensions of our everyday world. We really can't picture them, but we can draw analogies with things we can picture to understand how they work. Also, just like we can draw a picture of a 3D scene on a 2D piece of paper, we can also view 2D or 3D pictures of higher-dimensional objects and understand something about them. Admittedly, I don't have the training to do that, but those who have studied the subject can.
Visualizing nothing is impossible, since we can't even comparisons to anything else. Even visualizing blackness is wrong, since that blackness fills some area, which requires dimensions, and dimensions are something.
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Some people (mostly philosophers) think that even the description of ''nothing'' is still something when compared. So language necesserily breaks down in this physics.
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We have 'absolute zero', can we therefore use the term 'absolute void' to describe an inconceivable nothingness?
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It's a misuse of scientific idiom, not to mention the term absolute zero does not even exist physically.
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If more than one universe exists, and if nothing exists outside each universe, can we say anything about the relative positions of the universes?
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If more than one universe exists, and if nothing exists outside each universe, can we say anything about the relative positions of the universes?
No because universes are self-contained.
String theory however treats this ''nothingness'' as a multidimensional pool, so maybe from a string theory outlook we may see universes as bubbles arising in a more complex structure. I believe this is a matter of interpretation.
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No because universes are self-contained.
I guess that means you don't agree with David Deutsch's claim to be able to provide "proof" of interaction between universes.
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No because universes are self-contained.
I guess that means you don't agree with David Deutsch's claim to be able to provide "proof" of interaction between universes.
Far from it.
I remember work by him hoping to take a photograph of a parallel universe... Is this what you are referring to?
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If by ''interaction'' we mean, bruises left by another universe during the collision of multiverses in string theory, then I have already entertained the idea that string theory can allow for these types of interactions. It really is a matter of interpretation.
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QC, what I was referring to was Deutsch's idea that in the double slit experiment, when photons are sent through singly, interference comes from "shadow photons" in other universes.
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Tell me more about shadow photons, please.
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I've heard of shadow particles. A bit of me is telling me they are related?
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I've had some time to read over it. Apparently Deusch is using the double slit experiment to answer for the existence of parallel universes. This would mean that interference does not occur because wave imply an interference, again because particles are not existent two places at one time. Sorry bud, but as of recently, interference in the double slit experiment truely is down to particle interfering with each other as waves, in more than one place at any single time
http://www.stardrive.org/index.php?option=com_content&view=article&id=2875:einstein-was-right-you-can-be-in-two-places-at-once&catid=43:science&Itemid=82
No need for parallel universes.
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This is the many-worlds interpretation of quantum mechanics, correct? It's just one of several interpretations of what the mathematics of quantum mechanics means. All the interpretations give the same results for experimental tests, so there's no need to require extra universes.
Even if you like this interpretation (I admit I happen to like it), I'm not sure it even makes sense to ask what's in between the universes. We'd have to be able to experimentally probe the region in between universes to come up with any useful theory, which can't be done. We'd also be using the concept of geometry, which comes from observing how things behave within our universe, and expect it to apply to regions outside our universe. In fact, even saying "outside the universe" is problematic, since to be outside something implies that there is geometry outside of the universe!
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In fact, even saying "outside the universe" is problematic, since to be outside something implies that there is geometry outside of the universe!
Exactly. How would you "probe" nothing.
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Mathematicians have defined the Universe as boundary less and so an edge cannot exist in the Universe
Of course we the common thinking people understand that Mathematicians are by defintion incorrect