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Is the Universe Rotating?






Is the universe rotating?
Yes
22%
 22%  [ 5 ]
No
27%
 27%  [ 6 ]
Can't Say
50%
 50%  [ 11 ]
Total Votes : 22

justinrocks
Hi,

We all know that everything in the universe rotates, is it possible the entire universe is also rotating?

I read somewhere the universe does rotates and the rotation is merely measured to be small, one rotation in 6 quadrillion years (300,000 times the age of the universe). How true it is?

And if you say it doesn't rotate, how do we know the universe isn't rotating? We are inside it, not outside. We can't see if it's spinning. At first, we thought the earth didn't rotate. The only reason we figured out that it does was because we could see the sun, stars, moon, planets and andromeda.

Any clear answer?
Bikerman
So where did you read that? A comic? A science paper? The Daily Bugle? It's quite important to know.
The answer to the question is probably not. If the universe is rotating then the angular momentum would produce a large scale anisotropy* in the Cosmic Background Microwave Radiation (CMB). This does not appear to be present - the anisotropy present in the CMB is small scale and there is no general 'unevenness' along any possible axis of rotation.

The idea that the universe is rotating is also an 'ugly' idea in physics. (That doesn't mean that it is wrong, of course, but ugly theories usually are). If the Universe is rotating then it would mean that there are 'special' places in the universe (the hub, for example) and this would violate the cosmological principle - very ugly.

*If you don't know what that word means then look it up and learn something.
Flarkis
Ya with what Bikerman said this would make for some very ugly physics. It would be the equivalent of having a bucket full of water and spinning it in a circle.
uuuuuu
This question, whether the Universe itself is rotating, may be of fundamental and profound importance to our understanding of the nature of the Universe. Here are some of my own ideas and questions concerning the subject:

First, a question. If the entire universe were rotating, how would we know?
Consider a trivial Universe, containing only a single particle. Is that Universe rotating?
I don't think we could measure the rotation of that particle without appealing to a point of reference outside of that particle, could we?
The particle might have properties, like rotational inertia, but does rotational inertia have meaning in this trivial Universe? It would be hard for me to make sense of that.

Second, is there such a thing as absolute space? As a concept we're all familiar with it, that there is an absolute space that's unaffected by the matter that may or may not live in it at any given time. But can we even consider space without using matter to describe it? I can't.

It has been posed, in answer to this question, that a rotating Universe would be ugly, as it would violate the cosmological principle. Now, I'm no scientist, but I don't particularly care for the cosmological principle, here's why:

It says, as I understand, that at a "large scale", the Universe is Isotropic and Homogeneous. What this means to you and me, is that no matter in what direction we look, everything is pretty much the same, and no matter where we are in the Universe, everything is about the same.

This idea, applied to the Cosmic Microwave Background radiation data, is foundational support for the big bang theory.

But what the principle fails to take into consideration, in my view, is the limit of the scope of human understanding of the Universe. Let's say that we applied the Cosmological Principle not to the microwave background radiation, but to local atmospheric data.

At any time and place in Earth's atmosphere, the relative air pressure is increasing or decreasing. If we found that the pressure was decreasing, we could generalize by applying the cosmological principle that all of the matter in the universe was moving further apart from all other matter, and would continue to do so indefinitely. We're trying to generalize local data to a Universe beyond our ken, which seems silly to me.

This post is starting to get boring for me to write, so I know it must by twice as boring for you to read, so I'll cut it off here with a link to an interesting discussion about rotation, which touches on the Newton's Bucket thought experiment, and Mach's Principle.

Say hi to your moms for me,

Love,

Uwe

http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Newton_bucket.html
Bikerman
Quote:
This question, whether the Universe itself is rotating, may be of fundamental and profound importance to our understanding of the nature of the Universe.

Why?
If you adopt a Machian perspective (as you appear to do) then, far from being important, the question is meaningless. Mach would have said that without any external 'reference point' there can be no rotation and therefore it is meaningless to talk in such terms. I don't personally agree with that, since my understanding of General Relativity (GR) in this context is that it is an essentially non-Machian 'picture' of the Universe. I know that Einstein actually thought that GR was Machian at the time - but, as explained in your link at the end, when you remove all matter from the universe then you also remove gravity, at which point GR collapses down into Special Relativity - in which spacetime is an absolute, since all observers would see the object (spinning bucket of water, or spinning rocks connected by a rope) accelerating with respect to their own frame of reference. Thus the water would 'climb' the sides of the bucket and the rope would become taut - ie we would see rotational effects.
uuuuuu wrote:
At any time and place in Earth's atmosphere, the relative air pressure is increasing or decreasing. If we found that the pressure was decreasing, we could generalize by applying the cosmological principle that all of the matter in the universe was moving further apart from all other matter, and would continue to do so indefinitely. We're trying to generalize local data to a Universe beyond our ken, which seems silly to me.

That is not how the CMB is measured so the analogy does not work. You could perhaps have made that criticism of the first COBE observations but the more recent WMAP survey was a full 360 sweep.

The Cosmological Principle simply says that no position in the universe is privileged - the universe is the same all over, on a large scale (though there are small scale variations).
In physics that is a 'nice' assumption because it fits in with the way we know things work - it represents a fundamental 'symmetry'. It could, of course, be wrong but the COBE and WMAP data suggests otherwise.
uuuuuu
Thanks.

Wow, you're so smart!
Bikerman
uuuuuu wrote:
Thanks.

Wow, you're so smart!

Not really - just an old teacher Smile

PS - I edited the above text several times to try and present a fairer picture so you may have missed some of the edits.
HalfBloodPrince
Anyway, if it's rotating or not, we don't need to worry about it. Maybe our great grandchildren^7000, but certainly not us. Very Happy
Bikerman
HalfBloodPrince wrote:
Anyway, if it's rotating or not, we don't need to worry about it. Maybe our great grandchildren^7000, but certainly not us. Very Happy
Why would our descendants need to worry? There's a lot of things that we don't need to worry about - that doesn't mean we shouldn't ask the questions. I believe in knowing for the sake of knowing - and the bonus is that sometimes what appears to be purely esoteric knowledge turns out to have practical uses...
tijn01
Believe in knowing for the sake of knowing..... interesting. But,


the more you know, the more you know you don't know, becoming aware of some knowledge, often also makes you aware of the things you don't yet know. So knowing for the sake of knowing to become aware you know less. Interesting! :shock:
Bikerman
Knowing that you don't know something is itself knowledge. Ignorance is not bliss Smile
uuuuuu
Bikerman,

I appreciated your thoughtful response to my last post.
Though somehow I wasn't able to craft the crux of my argument well enough that I think you understood my meaning, you introduced me to two assessments of our sky that I find interesting, the COBE and the WMAP.
Having consulted with wikipedia, I'm not convinced that I have any better of an understanding of them now than I had before.
I have a fundamental understanding of what the CMB is, but I fail almost completely to understand either of the surveys.
Would you mind breaking them down and explaining them in chunks that you would expect an average high school student to be able to understand?

Also, let me recapitulate for just a second, my analogy. I was in a hurry last time, and I think I blundered when I was trying to present it.

Ok, the Big Bang Theory, which is supported by the Red-Shift data and the CMB data, asserts that because we observe that light from more distant objects in the Universe is shifted more toward the red than nearer objects, all matter in the Universe was once concentrated at a nearly infinite density but is now accelerating away from all other matter, and will continue to do so, indefinitely. But now consider an experiment of two separate measurements of local air pressure, one made at the same place, a certain amount of time after another. This experiment is made by an observer, the scope of whose Universe is limited to the order of maybe 10^1 meters.

The first result is X_1 mm of mercury, and the second result is a fraction thereof -- indicating a decrease in local air pressure between the first and second experiments.

Well, what now, if, relying on the Cosmological Principle, the experimenter concludes that because in the interval of time and in the place of the experiment, that since all matter is moving closer together and becoming more dense (increased air pressure means increased density of air molecules), that the same thing is happening throughout the Universe? This conclusion is positively as valid via the Cosmological Principle as is the universal expansion is via red-shift data. Both are conclusions about what is happening Universally based on what is observed to be happening locally.

Anyway, chew on that and get back to me about WMAP and COBE when it's convenient for you.

Regards, etc... etc...
Indi
uuuuuu wrote:
Well, what now, if, relying on the Cosmological Principle, the experimenter concludes that because in the interval of time and in the place of the experiment, that since all matter is moving closer together and becoming more dense (increased air pressure means increased density of air molecules), that the same thing is happening throughout the Universe? This conclusion is positively as valid via the Cosmological Principle as is the universal expansion is via red-shift data. Both are conclusions about what is happening Universally based on what is observed to be happening locally.

That would be a rather impressive abuse of the cosmological principle. ^_^;

No, that conclusion does not follow from the cosmological principle. Comparing it to the red-shift observation highlights the flaw. Here's what that conclusion would look like if it followed the same logic: "A scientist measures the red-shift of the Sombrero galaxy and measures it to be ~1 Mm/s. Using the cosmological principle, he concludes that all galaxies are moving away at ~1 Mm/s." Obviously not, right?

The cosmological principle states that when viewed at cosmic scales, everything is homogeneous. But the scale of 10 meters, all bets are off. Hell, at the scale of galaxies all bets are off. You have no way of knowing whether or not you happen to be measuring a local spike or dip.

i know you want to say "well, by the same token, how do we know that our red-shift (or CMB) measurements aren't also in a local spike or dip?" The answer is because we have measured in all directions, not just one. To use your analogy, we have taken pressure measurements at thousands of points all over as far as we can see. This would give us a very nice 3D topographical map of the pressure variation, which we could then use to make some pretty powerful observations of the nature of the air. What we have observed (by analogy) is that the air has the same pressure everywhere.

To put it back in cosmological terms, we measured the red-shift of galaxies as far away as our instruments can detect, in all three spatial dimensions. From that we plotted out a 3D map of the red-shift data, and observed that it supports a homogeneously expanding universe, as we would expect. That gives us strong reason to support the cosmological principle. Then we took CMB measurements in all directions, and found that it, too, was pretty much homogeneous. Then we apply the cosmological principle (which was supported by the other data), along with the CMB data we have, and we can logically conclude the CMB is the same everywhere.

It is still possible that the universe is not homogeneous, and that if we go a thousand or a million light years away, we'll measure something different. But the odds of that are ludicrously small. In order for that to be true, not only would there have to be variation in the CMB, but it would have be precisely varied in just the right way such that it so happens that our Earth happens to be at a point where the variations measured in all directions perfectly cancel out.

That's a bit of a stretch. ^_^;
Bikerman
Wot Indi said Smile
(seriously, that explains it at least as well as I could have done).
Cddhesh
I read different things about our universe in different articles.Some sya universe is shrinking and some says universe is expanding.Both gives good reasons,reading that i am confused a little bit ,that which one is true.
Bikerman
Cddhesh wrote:
I read different things about our universe in different articles.Some sya universe is shrinking and some says universe is expanding.Both gives good reasons,reading that i am confused a little bit ,that which one is true.

Perhaps you could cite your source for saying the universe is shrinking? I have seen nothing that would make me believe that is a real possibility. The consensus is that the universe is expanding - this is the model that most, if not all, cosmologists agree with and it is supported by observation.
We can see distant galaxies receding from us - this is measured by the shift in wavelength of the light we receive, a process analagous to doppler shift (when an ambulance moves away from you, its siren is 'lower' in pitch than when it moves towards you - most people have experienced this). The same thing happens with light from distant galaxies - if they are moving away from us, the light is 'shifted' towards the red end of the spectrum. We call this process redshift.


(source - http://en.wikipedia.org/wiki/Redshift )

By measuring the redshift we can calculate the speed that such galaxies are moving away from us. Edwin Hubble noted that the further away a galaxy is, the greater the redshift. That means that galaxies further away from us are moving away faster. This finding has since been confirmed many times by more recent observations.
uuuuuu
So, I appreciate the feedback on my last posting.
You obviously read it, and you obviously mostly understood it, but I think I'm still failing to drive my point across.

Let me make a few small clarifications concerning my analogy please...

Ok, so, first of all, it's only a thought experiment. It's a hypothetical.

What I'm comparing is an observer whose universe is limited (because he can't see or travel beyond the order of tens of meters) to a scope of about 10 meters, with an observer whose universe is limited (because he can't see any further, either) to about 1.3e27 meters. That's you or me.

Well, the analog between measurement of air pressure and the measurement of red shift is probably stronger than you're thinking. One of them is taken with, say, a barometer, and the other with a spectrometer. Each of them remain stationary, but can be rotated to take measurements in any direction. Statistically, air pressure will be very independent of direction of measurement, so will be red shift.

Given the two data sets, the cosmological principle leads to totally different inferences between these cases. We think of ours as being more correct, because we want it to be, and it's true that our measurement is taking data from a lot larger portion of the Universe, but both are using an inference about what's happening locally (read: as far as can be measured), and generalizing toward what's beyond what can be seen, which doesn't ALWAYS work.

Also, in each case, it's just a best guess, based on available data.

But holes are starting to show through the Big Bang theory, and the patches that are being applied to them are disgustingly ad hoc, and ugly!

According to the WMAP survey, only 4.6% of all that which is in the Universe is ordinary baryonic matter (That which we can see, touch, or otherwise sense). The other 95% is dark matter or energy, something that we can't see, hear, touch, taste, or smell, and you wouldn't know it if you saw it, but yet it still exists, by MAGIC, in order to make the model work.

But yet, the theory is still agreed upon by the vast majority of experts and non-experts. Which isn't surprising considering that it's impossible to get research money unless you subscribe to it.

Anyway, I've rambled enough, I hope you're starting to see my point, and I hope that we can all try to reason more, and think more, and be more circumspect in our lives.

Love to all,

Say hi to your moms for me,

Uwe
Bikerman
uuuuuu wrote:
Well, the analog between measurement of air pressure and the measurement of red shift is probably stronger than you're thinking. One of them is taken with, say, a barometer, and the other with a spectrometer. Each of them remain stationary, but can be rotated to take measurements in any direction. Statistically, air pressure will be very independent of direction of measurement, so will be red shift.
Err...no. A barometer measures the air pressure where it is positioned. A spectrometer measures the redshift (let's keep it simple) from the light where it is pointed. They are fundamentally different.
Let's say you point your spectrometer at Andromeda. You are measuring the light from Andromeda. The local conditions don't matter (beyond, of course, ensuring that you don't contaminate the reading with ambient light). What you are measuring is the light which has travelled from the Andromeda system. By measuring the redshift you measure the rate of recession of the Andromeda galaxy from your point of observation. You can't do that with the barometer - it takes a reading from where it is - pointing it at Andromeda makes no difference.
Quote:
Given the two data sets, the cosmological principle leads to totally different inferences between these cases. We think of ours as being more correct, because we want it to be, and it's true that our measurement is taking data from a lot larger portion of the Universe, but both are using an inference about what's happening locally (read: as far as can be measured), and generalizing toward what's beyond what can be seen, which doesn't ALWAYS work.
But there aren't two data sets - there are many. You take a redshift reading from several telescopes. When they agree - which they do - then you know that the light received has redshifted by a certain amount. You then calculate the rate at which the galaxy is moving based on that redshift. The local conditions really don't matter. You could repeat the readings on the moon, in space - anywhere in the galaxy - they would still be roughly the same. We are measuring a fundamental property of the light which has travelled from the target to us - that property (the degree of redshift) will not depend on where you take the measurement. We know the speed of rotation of our own galaxy from observation. We know the speed of rotation of the earth around the Sun. We therefore know what our own motion is relative to the centre of the milky-way and can, if required, adjust accordingly (though this is not normally required because the expansion 'speeds' we are measuring are so high that any local 'movement' is just noise).
Quote:
Also, in each case, it's just a best guess, based on available data.
No, it's observational confirmation of a theory based on sound understanding of the principles involved.
Quote:
But holes are starting to show through the Big Bang theory, and the patches that are being applied to them are disgustingly ad hoc, and ugly!
Say's who? This sounds like the sort of comment made by someone with their own pet theory who is annoyed because the science community doesn't take them very seriously - unfortunately there are a lot of such people around.
Quote:
According to the WMAP survey, only 4.6% of all that which is in the Universe is ordinary baryonic matter (That which we can see, touch, or otherwise sense). The other 95% is dark matter or energy, something that we can't see, hear, touch, taste, or smell, and you wouldn't know it if you saw it, but yet it still exists, by MAGIC, in order to make the model work.
No. The existence of dark matter is hypothesised for several reasons - not simply to make the Big Bang theory work. Observed rotation of galaxies, for example, requires additional matter to be present - otherwise they would fly apart, and we know that isn't the case by simply looking. We also have confirmation from gravitational lensing observations.
Quote:
But yet, the theory is still agreed upon by the vast majority of experts and non-experts. Which isn't surprising considering that it's impossible to get research money unless you subscribe to it.
That is simply not true. Any physicist who could show that the BB theory was not correct would stand to gain a Nobel prize. There are many physicists and cosmologists working on alternate theories of cosmology - you must have heard of the Steady State theorists? There are lots of physicists doing 'blue sky' thinking about basic physics and cosmology. Some of the more interesting include;
Lee Smolin
and
Steinhardt and Turok
The notion that physicists are somehow 'prevented' from challenging fundamental concepts like the Big Bang theory is one often put around by opponents of the theory - whatever their motivation might be. It is simply untrue and is a gross insult to the physics community. The problem is that many alternative theories are pseudo-science and new age bunkum. These are, rightly, treated with the contempt they richly deserve.

The reason the BB theory is supported is because it best fits the available data - simple.
Theories such as the BB are not simply pulled-out of the air. They are the result of detailed theoretical work which is then confirmed (or refuted) by observation. In the case of the BB the killer evidence is the Cosmic Microwave Background. The theory demanded that this be present and detailed calculations showed what level it should be at. This was theorised long before the CMB was actually observed and that provides compelling evidence. The fact that galaxies are all receding from us is good supporting evidence. Other support comes from;
a) Relativity. Einstein's Relativity requires that the universe is expanding or contracting. He didn't like the conclusion and added the cosmological constant to balance things out
b) Observations of the age of stars in our own galaxy - the oldest being about 13 billion years which fits nicely with the theory
http://news.bbc.co.uk/1/hi/sci/tech/3573914.stm
c) Observations of the most distant galaxies - between 12 and 13 billion light years away - again this fits with the theory.
http://www.space.com/scienceastronomy/distant_galaxy_040216.html
d) The abundance of light elements particularly deuterium (which cannot be produced by any other mechanism we know about).
http://map.gsfc.nasa.gov/universe/bb_tests_ele.html
e) The radioactive materials found in interstellar space. Using the half-life and calculating backwards gives us a figure around 13 billion years...
http://www.sciencedaily.com/releases/2005/06/050630064319.htm

In short, the evidence for the BB is overwhelming.

You might find the following useful - it's a little paper I wrote on this some time ago..
http://bikerman.info/resources/mywork/universe-guide/universe-guide.htm
uuuuuu
This will be my last post to this thread.
I'm starting to find it boring, and the vitriolic responses to my posts make it clear that the prevailing mode in this forum is not discourse, but closed-minded banter.

I make a final attempt to help any reader that is still confused as to my remarks to understand:

As bikerman responded to my penultimate post:

"Err...no. A barometer measures the air pressure where it is positioned. A spectrometer measures the redshift (let's keep it simple) from the light where it is pointed. They are fundamentally different."

I reply that your disrespectful tone reveals your insolence to all. From your first two words I understand that you have no interest in dialog, but only in proving your intellectual superiority, which, to my understanding isn't the subject of our discussion. At any rate, it's this attitude that has influenced my decision to end our discussion.

Second, your understanding of these measuring instruments is incomplete. Any measurement is a consequence of local interaction. The measurement of a barometer is isomorphic to a local interaction between bodies of fluid or gas. As they (barometers) are typically used, boundary conditions between atmospheric air and an indicating liquid, usually mercury, reveal information about the state of the air. One thing to note, is that air pressure levels are not necessarily isotropic. Whenever you feel the wind blowing, you're experiencing air pressure anisotrpies. A cleverly constructed instrument would be able to detect these. At any rate, the instrument measures air pressure in the direction that it's pointed, as does a spectrometer.

Now, a spectrometer, pointed at Andromeda as in your example, isn't directly measuring Andromeda. It's measuring a local interaction between multitudes of photons detected to have been emitted in the direction of Andromeda, and (probably) a prism, or maybe some more advanced detector, I'm not very familiar with spectroscopy.

-- You know what... I just realized I don't care if you understand this.

Congratulations on being so smart.

Peace out!

Uwe
Bikerman
uuuuuu wrote:

-- You know what... I just realized I don't care if you understand this.

You are talking complete nonsense so it will be a relief, to be honest, if you stop. I was making my own barometers 30 years ago, so I think I know how they work without the 101 lecture. The barometer makes a reading, where it is positioned, of the local air pressure AT THAT POINT. It tells you nothing else, it is an entirely localised reading of a localised phenomenon. What part of this do you not understand?

As for local interaction in measurement - yes, of course, that is how measurements are made. What has that got to do with anything? It is what you are measuring that is important, not the mechanics used to make the measurement itself. The spectroscope makes a calibrated reading of the 'colour' of photons emitted from (in this case) Andromeda. The actual method of doing this is not relevant (so long as it can be calibrated and repeated consistently) since the property you are measuring is the important thing. Your spectroscope is telling you something about Andromeda (as it was 2.5 million years ago).
Point your barometer at Andromeda and it will continue to tell you what the air pressure is where it is located, it will tell you nothing else - ever.

PS - if you find my comments vitriolic then you really need to toughen-up a bit. I avoid personal comment as a matter of policy, and confine my comments to the arguments/postings I respond to. The strongest words I use are words like 'nonsense', 'pseudo-science' and the like. If you find that vitriolic then...wow!
I don't understand why you think I should be respectful to you? I am courteous (as I try to be with anyone) but respectful? What have you done to earn my respect?
When you respect someone's views it means that you take them into account and you may even change your own views or decisions accordingly. I don't respect your postings on this matter and see nothing of importance to take into account. If you had something to say which was based on research of your own, or based on a sound theoretical understanding of the concepts involved then it might be different - I see no such understanding. Deal with it.
TBSC
uuuuuu wrote:
This will be my last post to this thread.
I'm starting to find it boring, and the vitriolic responses to my posts make it clear that the prevailing mode in this forum is not discourse, but closed-minded banter.

I make a final attempt to help any reader that is still confused as to my remarks to understand:

As bikerman responded to my penultimate post:

"Err...no. A barometer measures the air pressure where it is positioned. A spectrometer measures the redshift (let's keep it simple) from the light where it is pointed. They are fundamentally different."

I reply that your disrespectful tone reveals your insolence to all. From your first two words I understand that you have no interest in dialog, but only in proving your intellectual superiority, which, to my understanding isn't the subject of our discussion. At any rate, it's this attitude that has influenced my decision to end our discussion.

Second, your understanding of these measuring instruments is incomplete. Any measurement is a consequence of local interaction. The measurement of a barometer is isomorphic to a local interaction between bodies of fluid or gas. As they (barometers) are typically used, boundary conditions between atmospheric air and an indicating liquid, usually mercury, reveal information about the state of the air. One thing to note, is that air pressure levels are not necessarily isotropic. Whenever you feel the wind blowing, you're experiencing air pressure anisotrpies. A cleverly constructed instrument would be able to detect these. At any rate, the instrument measures air pressure in the direction that it's pointed, as does a spectrometer.

Now, a spectrometer, pointed at Andromeda as in your example, isn't directly measuring Andromeda. It's measuring a local interaction between multitudes of photons detected to have been emitted in the direction of Andromeda, and (probably) a prism, or maybe some more advanced detector, I'm not very familiar with spectroscopy.

-- You know what... I just realized I don't care if you understand this.

Congratulations on being so smart.

Peace out!

Uwe


It sounds to me like maybe you've been talking to some uptight scientists, but to me Bikerman seems mellow enough. In addition he has taken his time here to thoroughly explain things to you, and it was thrown back in his face. I don't think he is condescending. Disagreement is not condescending. But I understand it probably seems that way if you have been talking to some uptight scientists.... lol Smile
pinkie
hmm, i don't think so.
jmaninc68
WHO CAN HONESTLY SAY THEY KNOW 100& if the universe rotates or not
Indi
jmaninc68 wrote:
WHO CAN HONESTLY SAY THEY KNOW 100& if the universe rotates or not

The guy pinned up against the far side of it by the spinning force.
vineeth
As far as my knowledge, for every "movement" or "change", there should be an "unmoving" or "solid" base. On the basis of this only a movement occurs.

The basis of most of the movements in the cosmos is the force of gravity, which holds cosmos as one. If we are agreeing that the universe is also rotating, there must have another universe which puts gravitational (?) force on this universe and causes its rotation.

We are not sure about this, of course.
Bikerman
vineeth wrote:
As far as my knowledge, for every "movement" or "change", there should be an "unmoving" or "solid" base. On the basis of this only a movement occurs.

The basis of most of the movements in the cosmos is the force of gravity, which holds cosmos as one. If we are agreeing that the universe is also rotating, there must have another universe which puts gravitational (?) force on this universe and causes its rotation.

We are not sure about this, of course.

So you maintain a Machian position then?
Let me clarify. Mach posited that, in the absence of reference points, the concept of movement is meaningless. Newton, on the other hand, said that absolute space was a reference point and that any measurement could be referenced to space.

Now, imagine a bucket of water in deep space with no surrounding stars. Spin the bucket. Does the water climb the sides of the bucket according to normal rotational dynamics (since it is being accelerated) or does it not? Mach would say that only if the bucket is rotating relative to a fixed point of reference does the water climb the sides. In the absence of surrounding matter there is no concept of rotation and the water will remain level.
Newton, on the other hand, said that the water will climb the sides regardless, since the bucket is accelerating with regard to empty space.

This is a surprisingly deep question in physics - I'll leave you to decide who was right, Newton or Mach..
http://en.wikipedia.org/wiki/Newton%27s_bucket
http://en.wikipedia.org/wiki/Mach%27s_principle
Starrfoxx
It would make sense for it to rotate. Planets do. Suns/stars rotate around a galaxy, and galaxys rotate around each other, so I'm sure the universe is rotating around something.... maybe even God.
Xrave
well, rotation is relative.

if everything in the universe is rotating, it's not. correct? but then the universe is truly rotating. yet you can't see unless you hop out of the universe and compare this one with the next one. and since you can't do that, it's impossible to know.

the earth is rotating, but if there is no stars and moon and sun, why would anyone find out? distance between two objects on the earth remains the same regardless of its rotation.
Bikerman
Xrave wrote:
well, rotation is relative.
Is it? Uniform motion is certainly relative, but acceleration isn't (necessarily). When you accelerate an object there are observable effects (see the Newton's Bucket example). If the universe were rotating (acceleration) then we might expect to see some effect of that rotation.
The problem with simple rotation is that it must be rotating around an axial point. This would violate the cosmological principle (ie it would mean that there is a 'special' place in the universe).
chatrack
Hi,

As far as we know every thing - planets - stars - are rotating about some center.

So proceeding like that, the universe may be roatating about some center point, may be

the rotation speed is so small to detect.

Rolling Eyes
mhamad84
this is an interesting question..
pscompanies
This question, whether the Universe itself is rotating, may be of fundamental and profound importance to our understanding of the nature of the Universe. Here are some of my own ideas and questions concerning the subject:

First, a question. If the entire universe were rotating, how would we know?
Consider a trivial Universe, containing only a single particle. Is that Universe rotating?
I don't think we could measure the rotation of that particle without appealing to a point of reference outside of that particle, could we?
The particle might have properties, like rotational inertia, but does rotational inertia have meaning in this trivial Universe? It would be hard for me to make sense of that.

Second, is there such a thing as absolute space? As a concept we're all familiar with it, that there is an absolute space that's unaffected by the matter that may or may not live in it at any given time. But can we even consider space without using matter to describe it? I can't.

It has been posed, in answer to this question, that a rotating Universe would be ugly, as it would violate the cosmological principle. Now, I'm no scientist, but I don't particularly care for the cosmological principle, here's why:

It says, as I understand, that at a "large scale", the Universe is Isotropic and Homogeneous. What this means to you and me, is that no matter in what direction we look, everything is pretty much the same, and no matter where we are in the Universe, everything is about the same.

This idea, applied to the Cosmic Microwave Background radiation data, is foundational support for the big bang theory.

But what the principle fails to take into consideration, in my view, is the limit of the scope of human understanding of the Universe. Let's say that we applied the Cosmological Principle not to the microwave background radiation, but to local atmospheric data.

At any time and place in Earth's atmosphere, the relative air pressure is increasing or decreasing. If we found that the pressure was decreasing, we could generalize by applying the cosmological principle that all of the matter in the universe was moving further apart from all other matter, and would continue to do so indefinitely. We're trying to generalize local data to a Universe beyond our ken, which seems silly to me.

This post is starting to get boring for me to write, so I know it must by twice as boring for you to read, so I'll cut it off here with a link to an interesting discussion about rotation, which touches on the Newton's Bucket thought experiment, and Mach's Principle.
dickyzin
They say that the universe is expanding because other galaxies are moving away from us. Someone mentioned that the galaxies further from us are moving away from us at a faster rate. But can this also suggest that our universe may be rotating? If we are somewhere close to the centre of the universe, and other galaxies are closer to the edge of the universe, the rotation of the universe could be throwing other galaxies to the edge faster. I hope you all get my point.
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