Is the universe truly expanding?

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Drakkith
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okay, you do know that as something expqnd space is created, and has to be filled up by something, when i say void, i refer to this space wich has to eventually be replaced by something
That is incorrect. The expansion of the universe means that the distance between unbound objects increases over time. It does not mean that space is being filled up by anything. A key thing to note here is that expansion, as explained by General Relativity, is a geometrical effect, not a physical effect. What I mean is that while a balloon has to be filled up with air to expand, a physical effect, the expansion of the universe is a result of the geometry of the universe.

Okay, i assume you know about multiverse, there should be a boundry, that bounds everthing in our universe. If the universe is not expanding and its contants are being spread out, dont you think they would by now have spread outside of the universe?
Not really, but it depends on exactly what you mean by 'multiverse'. Galaxies can move outside of our observable universe and never have a chance to interact with us again, so you could almost think of them as existing in a separate universe, but this is simply a result of the accelerating expansion of space. They are still within our actual universe an will remain so forever.

Other types of multiverse theories are different and I couldn't begin to compare all of them.

I Think it is,logical to say that if realy the contants of the universe are moving apart and the universe is not expanding, then a few galaxies would be at that edge or outside
The phrases 'contents of the universe are moving apart' and 'universe expanding' mean exactly the same thing. As the distance between unbound objects grows over time, the universe expands. There is no physical barrier that is moving into empty space or into some void or multiverse sea or anything like that. (Not according to the standard model of cosmology at least)

Space is vaccum, does this vaccum expand? Where does it come from? if we measure it to be 15 today, and tomorrow it is 20 where did the extra 5 come from???
What are you measuring? If I were to measure the average density of space it would continue to decrease forever. If I were to measure the average distance between objects, it would increase over time. We can't measure 'the vacuum' because the vacuum is an absence of all matter. We have to measure real objects that exist within this vacuum, such as hydrogen and helium gas.

No. Space i a property of big bang, remember reason why space is said to be expanding is due to.the observation that after it banged everything flew apart, but flew apart into what?
There is no 'big bang'. The big bang was not an event. The big bang theory is a description of the evolution of the universe, starting from its extremely dense, extremely hot state right at the beginning of the standard model and running to the present day, where the universe has expanded and cooled over the course of 13.7 billion years. The common use of 'big bang' refers to an imaginary explosion which is where everything supposedly came from. This understanding is wrong. Nothing in the Big Bang Theory says anything about how our universe was created. It only explains that the universe started off hot and dense and expanded, cooling off over time. It serves as a framework in which to place many other theoretical predictions, such as the calculated abundance of the primordial elements and the evolution of stellar objects, in order to explain our current understanding of the structure and history of the universe as a whole. It does not suggest any ultimate origin for the contents of the universe.

In this it is uniquely similar to the theory of biological evolution. Biological evolution explain how organisms changed over the course of billions of years, growing from extremely simple single-celled organisms into the complex multi-celluar lifeforms we see today. The theory contains many, many other sub-theories that describe, in detail, all the different processes that lifeforms use/undergo. But, like how the Big Bang Theory doesn't explain the ultimate origin of the universe, evolution does not explain the ultimate origin of life. That is a separate theory known as abiogenesis.
 
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IM gonna go to bed now. Thank you so much for helping solve this, i hope we can continue some time... cheers
Tressure, I suspect that some of this conversation may be only weakly interacting :)

May I suggest that you have a look at the following article:

http://astronomy.case.edu/heather/us211.07/misconceptions.pdf [Broken]

This is an article by Charles Lineweaver and Tamara Davis, originally published in _Scientific American_ in 2005. It addresses your question (and several others) quite directly. It should provide the enlightenment you are seeking more lucidly than any clumsy attempt that I might make.

diogenesNY
 
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  • #28
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If you're in space and you pull your hands apart, there doesn't have to be something coming in between. Space is just seperation between things. It's nothing but "distance" (Except if you want to talk about photons, cosmic particles, virtual particles etc.)
 
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Tressure, I suspect that some of this conversation may be only weakly interacting :)

May I suggest that you have a look at the following article:

http://astronomy.case.edu/heather/us211.07/misconceptions.pdf [Broken]

This is an article by Charles Lineweaver and Tamara Davis, originally published in _Scientific American_ in 2005. It addresses your question (and several others) quite directly. It should provide the enlightenment you are seeking more lucidly than any clumsy attempt that I might make.

diogenesNY
Thank you i will have a look at it.
 
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Ii thought of somethig today ... after all the research i did online ...it makes sense to me that some matter is getting eaten by space, that is why it appears to be growing/ expanding. Then the big question would be: if this is true, which matter is it? Is it ev en possible for a matter to transform into nothing?
 
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If you're in space and you pull your hands apart, there doesn't have to be something coming in between. Space is just seperation between things. It's nothing but "distance" (Except if you want to talk about photons, cosmic particles, virtual particles etc.)
Space is expanding at an accelerating speed, what you are saying now is: galaxies are moving apart, which isn't what physicist are speculating about.
 
  • #32
Ii thought of somethig today ... after all the research i did online ...it makes sense to me that some matter is getting eaten by space, that is why it appears to be growing/ expanding. Then the big question would be: if this is true, which matter is it? Is it ev en possible for a matter to transform into nothing?
How could matter be eaten by space? What do you mean? Matter cannot transform into nothing as not even the nothing you think of (the absolute absence of everything else) really exists in our Universe. Particles can decay into other particles, but overall quantities in the event are conserved.

Space is expanding at an accelerating speed, what you are saying now is: galaxies are moving apart, which isn't what physicist are speculating about.
Physicists say that expansion = moving apart. Space expanding at an accelerating rate = galaxies moving apart at an accelerating rate. If the Universe consisted of two objects, then the two objects would simply "drift away" from each other. Both, at the same time, would measure the other object to be getting farther and farther away. That is all. Replace "objects" by "distant galaxies" and that's our Universe.
 
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Okay, i assume you know about multiverse, there should be a boundry, that bounds everthing in our universe. If the universe is not expanding and its contants are being spread out, dont you think they would by now have spread outside of the universe?
 
  • #34
Okay, i assume you know about multiverse, there should be a boundry, that bounds everthing in our universe. If the universe is not expanding and its contants are being spread out, dont you think they would by now have spread outside of the universe?
The idea of a multiverse is highly hypothetical. By that I mean we have absolutely no proof it is even a feasible concept. It may or may not exist. Anything you attempt to deduce from it is meaningless.
For the hundredth time: the universe is expanding because its contents are spreading out. That is what expansion means: for its contents to spread out, to get farther away, to move apart. In cosmology they are all synonymous. So yes, the Universe is expanding and its contents are spreading out. And yes, objects (galaxies) are constantly disappearing beyond the cosmological horizon, due to the accelerating rate of expansion. That does not mean they are disappearing into some strange, magical and unexplainable realm—they are simply so far away now that we cannot detect them anymore. They are still in the Universe, but not in the observable Universe. There is no need to invoke multiverses to understand this.
 
  • #35
Drakkith
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Ii thought of somethig today ... after all the research i did online ...it makes sense to me that some matter is getting eaten by space, that is why it appears to be growing/ expanding. Then the big question would be: if this is true, which matter is it? Is it ev en possible for a matter to transform into nothing?
No, it is not possible. Please stop speculating.

Okay, i assume you know about multiverse, there should be a boundry, that bounds everthing in our universe. If the universe is not expanding and its contants are being spread out, dont you think they would by now have spread outside of the universe?
The details of multiverse theories are beyond the scope of mainstream science at this time. At best we have vague guesses backed up with math and theories that are highly speculative and almost certainly wrong. As such, there is no answer to your question. While the possibility exists that there is a boundary, the prevailing belief is that the universe is either infinite and without a boundary, or finite, in which case it wraps back onto itself and also has no boundary.

What we do know is that objects which are not bound together through gravity or one of the other fundamental forces of nature are moving apart over time, with the recession velocity increasing linearly as the distance between the objects grows. This is exactly what expansion is, whether it's cosmological expansion or the expansion of a rubber band as it is stretched. We also know that the rate of this expansion was slowing over time until recently, when it began to increase once more. Hence we say that the expansion is accelerating.

What happens at the 'edge' of the universe, if one exists, is unknown and any guesses would be pure speculation and against PF rules unless backed up with a proper reference.

If you want to learn what we know about the universe then feel free to ask, but if you want to make wild guesses on speculative topics then I will close this thread. I understand that it can be hard to tell when you're overstepping the boundary between mainstream and speculation, so if you have any questions about it feel free to message myself or another mentor.
 
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Thank you i will have a look at it.
i am reading the document, and so far it is making me even more confused, because whats said there is the opposite of what everyone is saying here. they say that galaxies are static, only space between them is getting bigger. where as you guys are saying galaxies are moving apart, whose telling the truth here?
 
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i apologise for my speculations, i guess i just got a bit carried away.

Charles H and Tamara M.Davis in Scientific America INC wrote that galaxies are static, only that space between them is getting bigger. (obtained from diogenesNY's post is this document http://astronomy.case.edu/heather/us211.07/misconceptions.pdf [Broken]) is where i obtained this information.

now who is right and who is wrong?
 
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  • #38
Drakkith
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They both mean the same thing. Galaxies are not under a force that would accelerate them and be able to be measured by an accelerometer, so in that sense they are static. Yet they are indeed moving apart, so it is common to say that space is what is expanding. However, space is not a physical object. To measure the properties of space we have to observe how objects within space act. So saying that galaxies are receding from each other and saying that space expands mean the same thing in regards to what we observe. In any case, the theory itself only says one thing, its just difficult to convey what a highly mathematical-based theory says in its math in everyday language.
 
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  • #39
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Tressure, Space is expanding true, very true. And eventually accelerating at a high pace. Scientists still aren't much sure of the reason but they say it's due to the Dark Matter, or maybe the Dark Energy. Hope this answered you
 
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but they say it's due to the Dark Matter
No, certainly not. Dark matter is slowing expansion in the same way regular matter does.
Dark energy is accelerating it, and in our current universe dark energy wins.
 
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Thats why I said "or maybe the Dark Energy" please read what I said before quoting :headbang:
 
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Following this logic, you would not object to the statement "scientists say the moon is made out of cheese, or maybe rock"?
 
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Okay, my fault, but cheese and rock are two completely different things. But not Dark Matter and Dark Energy aren't that much different
 
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Dark matter and dark energy are completely different things. The only common things are one half of their English names, and that we cannot observe them in labs (yet?). Cheese and rock are much more similar.
 
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Inbox please. But I guess the 'topic starter' would have got his answer by now.
 
  • #46
As an complete armature I think its misdirected to think our Universe is self contained when it is probably exposed to whatever is outside of our universe - it is interacting with our neutrinios as its anti matter collides with them, extinguishing the anti matter (as usual) and creating more Space. Neutrinos go in all directions so Space is expanding in all directions. Simple. Wish I could do the math to see if I'm right or wrong though.
 
  • #47
Drakkith
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As an complete armature I think its misdirected to think our Universe is self contained
The question of whether the universe is self-contained or whether it exists within a multiverse is not a simple one and there is no way to resolve it at this time. There may never be a way to resolve it. Since we are observing our own universe, and have zero evidence for a multiverse, I think it makes sense to take the stand of a single universe at this time. It's certainly the right thing for modern cosmology to do at this time.

it is interacting with our neutrinios as its anti matter collides with them, extinguishing the anti matter (as usual) and creating more Space.
None of this makes any sense in terms of real science. Please avoid giving personal opinions and theories, especially when you're unfamiliar with the physics involved.

Wish I could do the math to see if I'm right or wrong though.
Sorry that this is blunt, but it's not that you're wrong, its that you haven't even made a logical, coherent claim that makes any sense. We know how anti-matter and neutrinos work. We know much about the expansion of space. Neither of them work like you're imagining.
 
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No, certainly not. Dark matter is slowing expansion in the same way regular matter does.
Dark energy is accelerating it, and in our current universe dark energy wins.
at ashuchiha and everyone:
no, that doesnt answer my quest. i need to know how can nothing grow in size, is there any matter that is getting taken out of our universe, i just struggle to making sense that how can nothing grow at an accelerating rate.

imagine vacuum in bottle for instance, for there to be more of it (vacuum) in that bottle, more air has to be sucked out. which is why i suspect that there could be some matter large in size, and somehow is disappearing.
 
  • #49
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E=mc^2 I guess this could help you ? http://en.wikipedia.org/wiki/Mass–energy_equivalence . If there is a vacuum formed it means there is no air right? Then why more air needs to be sucked out? Vacuum is a space entirely devoid of matter {By wiki}. So I don't need it needs to suck out more air unless/until there is another external force acting on it which may put a hole in it letting the air inside it or any other circumstances that would lead to the pathway of Air to that bottle
 
  • #50
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at ashuchiha and everyone:
no, that doesnt answer my quest. i need to know how can nothing grow in size, is there any matter that is getting taken out of our universe, i just struggle to making sense that how can nothing grow at an accelerating rate.

imagine vacuum in bottle for instance, for there to be more of it (vacuum) in that bottle, more air has to be sucked out. which is why i suspect that there could be some matter large in size, and somehow is disappearing.
I didn't see anyone say it explicitly, but what is being created is more distance...that is the meaursed difference.
 

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