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korosten
Is there proof (and what is it?) that *space itself* is expanding, compared to the objects/matter just getting more distant from each other?

If space itself expands, won't the matter in it expand too and all "measuring sticks" in it/coordinate systems etc - so how can we possibly "notice" that space itself expands vs just the matter in it?

In other words, could it be (theoretically) that:

a) spacetime was always there, but the matter in it was created in a "big bang" and has been expanding in this existing space

b.) or that the visible universe is tiny compared to the actual spacetime, and that whatever we see was just one of possibly multiple "big bangs"? (But then again, it would mean that there was spacetime before "us"

I can see that methematically, and as a paradigm, we think of space or time not existing before the BB, but is this also true in reality, and what is the proof?

Thanks,
Chantal
korosten
Come on - anyone :-)? Someone surely knows a proof or has a good link?

Thanks,
Chantal
kjw
its a puzzling question, because if space was to expand what does it expand into ?

"However, if we tried to use other explanations for the red shifts we see from distant objects, you would end up with measurable consequences that are even harder to accept than the dilation of space."

it is all observational evidence

was space always there ? if it was, since there was no matter or energy present, then there are no things to reference time or space i.e. if there were no particles then there is nothing to measure distance, if there is no distance to measure then how do you measure time ?

its a profound question and I wish I could offer you more than, without matter or energy you can not define space or time.

Nick
It(expansion) is symptomatic of a closed universe. Finite yet unbounded.
The galaxy clusters are not moving away from each other through preexisting space. The distance inbetween is expanding.
Zephir
QUOTE (kjw+Nov 28 2006, 11:48 PM)
because if space was to expand what does it expand into ?

By AWT the Universe is formed by the interior of super-massive black hole, and the expansion of space is in fact the manifestation of gravitational collapse of such black hole and gradual increasing it's density and temperature (the overall speed of energy spreading slovens in such environment). By clicking to the picture bellow you can see/download the AVI animations at better resolution.

By such way, the Universe doesn't expand, it collapses instead with increasing speed like common stars, which can explain the dark energy phenomena.
korosten
kjw:

The redshift can be explained easily I thought!

- things, like galaxies, that move a way fast have a redshift according to special relativity

- gravitation (LOCAL curvature of spacetime) creates redshift according to general relativty.

This does NOT seem to contradict the idea that indeed, the *galaxies* are moving away, and not just *SPACE* :-).

Am I missing something?

So I have no problem with local curvatures of spacetime, or even global curvature of spacetime (if the universe were not flat).

But I do NOT understand why the entire space of the entire universe is supposed to expand vs just the *matter* in it (galaxies etc).

Chantal :-)
korosten
QUOTE (kjw+Nov 28 2006, 08:48 PM)
was space always there ? if it was, since there was no matter or energy present, then there are no things to reference time or space i.e. if there were no particles then there is nothing to measure distance, if there is no distance to measure then how do you measure time ?

kjw,

I see no problem or contradiction with spacetime and no matter.

Why couldn't there be just empty spacetime? (and maybe it wasn't empty at all!)

There could still be those random quantum fluctuations etc... just like there is now "between" matter in the vacuum.

So time would still exist - because of these fluctuations etc.

Chantal
kjw
yes my comment is not questioning the explanation of redshifts, its saying that if you do not believe that the space between galaxies is expanding then you have to accept that galaxies are traveling away from us at speeds greater than c. matter can not travel faster than c but space can.

i use the theories put forward by Einstein, since these have experimental evidence to back up the theory.

others theorists, Brian Greene and Steven Hawking have written about alternative origin theories. The only problem is how to test these ideas the way that scientists have tested other ideas to see if they are true or not.

i have chosen to accept The Big Bang CREATED space, time, matter, energy and gravity. I have also accepted that these theories may be wrong, but until I see experimental evidence of string theory, 11-dimensional brane theory etc I'll keep the Einstein description.

Nick
--" gravitation (LOCAL curvature of spacetime) creates redshift according to general relativty."

Light is only emitted with a redshift. It does not loose energy in transition out of a gravity well. Its energy is conserved and there is no Tired Light.

Mitch Raemsch -- Light Falls--
korosten
QUOTE (kjw+Nov 28 2006, 11:26 PM)
...then you have to accept that galaxies are traveling away from us at speeds greater than c. matter can not travel faster than c but space can.

Oh really? I didn't know that.

I saw in the link that *gravity alone* can't explain it, but what if you consider gravity and speed?

So even a combination of gravity AND the galaxies moving away won't explain the redshift?

How much is the largest measured redshift?

Chantal
korosten
QUOTE (kjw+Nov 28 2006, 11:26 PM)
i use the theories put forward by Einstein, since these have experimental evidence to back up the theory.

Yes, I agree with that.

But it sounds to me like "cheating" a bit, when we simply say that space can expand with speeds greater than c :-), it seems "to easy" to just say that. (...and expand into what...?)

So even the experiments match so far, it doens't necessarily mean that Einsteins formulas (plus the followup work) etc are correct for everything.

Maybe they don't apply well enough yet for extreme situations like close to an event horizon, inside a black hole (singularities etc), and maybe not for the universe as a whole.

So I think we should consider that *maybe*, our formulas don't apply to everything - and of course, *maybe* they are right... but it seems that most people just say, ooh "space expands *of course*, and there is NO other explanation... " :-)

(For me, critical thinking is extremely important. Imagine someone in 200 years reading our theories, and laughing about all the stuff we believed like we do now for people who only believed in Newton ;-).

Chantal
korosten
QUOTE (Nick+Nov 28 2006, 11:30 PM)
Light is only emitted with a redshift. It does not loose energy in transition out of a gravity well. Its energy is conserved and there is no Tired Light.

proof it :-)
Nick
QUOTE (korosten+Nov 28 2006, 11:46 PM)
proof it :-)

General Relativtity is theory of the CONSERVATION of energy.

Its that simple!
korosten
QUOTE (Nick+Nov 28 2006, 11:50 PM)
General Relativtity is theory of the CONSERVATION of energy.

Oh really? that is news to me.... if you think it is that simple, then you should publish a paper and become famous!

That is still not a proof though....

Nick
Why should I prove it?

Obviously you are not familiar with General Relativty. Its ENERGY CONSERVATION cannot be ignored.
QUOTE (Nick+Nov 28 2006, 07:35 PM)
Why should I prove it?

Obviously you are not familiar with General Relativty. Its ENERGY CONSERVATION cannot be ignored.

Since you are so knowledgeable about General Relativity, would you care to explain how it is the "theory of the CONSERVATION of energy"?

QUOTE (kjw+)
yes my comment is not questioning the explanation of redshifts, its saying that if you do not believe that the space between galaxies is expanding then you have to accept that galaxies are traveling away from us at speeds greater than c. matter can not travel faster than c but space can.

Exactly. I'm curious though, is there any other reason why we know that space is expanding?
kjw
*vanadesse I am not aware of any other way that can show space is expanding. Maybe there may be some way on a quantum level to show this. I am not knowledgeable enough to offer any suggestions.

It is a fascinating topic and one that appears to be based on pure observation. I often wonder if space is expanding by a push from the big bang or is it being pulled out by some kind of negative pressure effect...

I guess some of its mystery is due to the fundamental nature of space.

korosten
QUOTE (Nick+Nov 28 2006, 11:30 PM)
It does not loose energy in transition out of a gravity well. Its energy is conserved and there is no Tired Light.

First, energy conservation applies to any physical system, whether you use GR or not... it has nothing to do with GR.

Second, when something goes from higher to lower gravity, it gains energy.
So even tough the photon frequency is red-shifted, the "conservation of engergy" is not violated.

Chantal
Nick
ENERGY IS CONSERVED
fizzeksman

Why should it be that when offered a choice between a simple and a complex solution to a perplexing problem the complex solutions almost always seem to win hands down? Is it because the complex offers a chance to stroke our egos and prove our mental acuity and powers of comprehension superior to the masses?

A true test of any solution should be exhibited, not in its complexity, but in its utility and exemplified by an ability to simplify rather than complicate.

The idea that the universe is expanding due to "The Big Bang" is a castle of straw built to explain a redshift detected in observing distant heavenly bodies by Edwin Hubble. The redshift can just as easily be explained as a shifted wavelength of tired light caused by light having travelled for millenia over vast distances.

With an acceptance of an alternate explanation for the detectable redshift, much of the complexity that is considered to be cutting edge contemporary physics, would tumble down like a house of cards.

The following is from another thread but seems to, perhaps, have relevance here.

Fizzeksman
QUOTE
Assuming gravitation/inertial equivalence and empirically this seems a safe assumption, then the source of both must be the same. Four hundred years of looking for something (a force), in and about an atom that will allow it to exert an attractive force over great distance on other atoms or massive particles, has produced nothing.

What must be done before we can conclude that it doesn't exist as such. There is a lack of necessity to delegate to physics a conclusion for an attractive force to exist, which would mean a second one or more would also have to exist to account for inertia, when both can be explained simply by another mechanical means.

If we look around the universe for something/anything capable of exerting an influence on massive objects from near and far, which would account for inertia as well as gravitation, we have to look no further than electromagnetic radiation.

Any electromagnetic radiation exerts a force upon any matter encountered and this force is called radiation pressure. The seemingly "attractive" force of gravitation can then be explained as a shading effect, where one massive body shields another creating an area of less radiational intensity between the two, creating a push of one object toward the other.

For this to be the case then gravity is an effect of inertial radiation. From this conjecture we can also conclude (according to this model) that inertial radiation is prevalent throughout the universe as we know it. We know this because of the distant stars and galaxies detectable with the powerful optical and radio telescopes available today.

The properties of the radiation that would account for inertia can be reverse engineered from empirical data.

In order for mass to resist acceleration from a state of rest and to resume the same state once acceleration ceases would imply a doppler effect when encountering the inertial radiation during acceleration. For a state of rest to occur regardless of relative velocity (perhaps less than relativistic velocity?) would imply that the probability of any given volume of space would have to contain enough radiation of all frequencies (wave count of all radiation in said space) to insure that the radiation encountered during and after acceleration would remain the same in all inertial frames.

korosten
So as you all know, Hubble found that redshift is proportional to distance.

Interestingly (I just learned), he was actually skeptical that this implies velocity only (dopper effect) that leads to the theory of the expanding universe. He warned again and again that there may be ohter, yet unknown effects that could explain (some of the) redshift.

It's interesting, I've *always* been a firm "believer" in the Big Bang, but now suddenly one question leads to another (it started with black holes :-), and more and more it all seems to be not a very solid "house of cards" that seems to crumble easily!

Can someone who knows more about the Big Bang post links that show more proof of the Big Bang than just the redshift :-) ?

Yes I know of course that we don't see farther than X billion lightyears, but it *could* be that light is simply absorbed over huge distances. I don't think that proves 100% that the univers is not in fact older (it is a very good indication, and I have been believing it forever, but I think it is not 100% certain!).

Chantal

QUOTE (kjw+Nov 28 2006, 08:37 PM)
*vanadesse I am not aware of any other way that can show space is expanding. Maybe there may be some way on a quantum level to show this. I am not knowledgeable enough to offer any suggestions.

I just thought of something else. The expansion of space is accelerating, right? So if everything was just moving away from each other, there would have to be some force pushing them apart. And that would lead to huge complications...
kjw
*vanadesse it does my head in. the acceleration of the expansion is puzzling. you are correct this acceleration needs energy input and dark energy is another hypothetical explanation.

fizzeksman tired light also remains hypothetical and if any experimental evidence is generated then I guess this could become a contender.

korosten if you understand maths check out Friedmann-Lemaître-Robertson-Walker (FLRW) metric. I have little idea of what it means or how to describe what it says, but if any one can interpret it in simple terms please help.

Since we all appreciate science then we surely must come to terms with that the big bang theory is just a theory. It will remain an accurate description of the universe until our technology, understanding and evidence forces us to re-define the universe. But until we have this evidence, what are we expected to believe.

korosten
QUOTE (*vanadesse+Nov 29 2006, 08:12 PM)
The expansion of space is accelerating, right? So if everything was just moving away from each other, there would have to be some force pushing them apart.  And that would lead to huge complications...

...and what is this observation based on, do you know? Also on the redshift :-) ?

Re complications: Isn't this acceleration odd, no matter if you consider *space* or *matter* moving apart? either way you would have to do some explaining ;-).

From what I know, the current theory is some "dark energy".

It seems weirder and weirder the more I think about it :-). All this, *space* that is expandng, dark energy, acceleration, inflation that is supposed to have different speeds different at different times, all just to explain this redshift that is a doppler effect?

What *if*, just as thought experiment, there indeed was another explanation for redshift (just IF). What if redshift did NOT mean galaxies moving away.

How would all the other observations fit?

For instance I read that pretty much *all* theories would predict a microwave background, not just the big bang! So that background radiation is NOT a proof for the big bang either (since it supports ALL theories :-)

Chantal
fizzeksman

By assuming mass/energy equivalence and inertia/gravitation equivalence:

What pecentage of the so called "dark matter/missing mass" of the universe can be accounted for by the energy density of space neccessary to account for (hypothetical) inertial/gravitational radiation?

Is it by an extremely happy accident that gravity experienced by massive objects on or near Earth's surface has almost exactly the same value as mass's resistance to acceleration?
OR...
Could it be that gravity as a shielding effect has a maximum penetration threshold which has "maxxed out" somewhere around or below the shielding effect offered by an object as massive as Earth?

.
korosten
fizzeksman,

Thanks,
Chantal
korosten
Hmm, interesting article about all these issues:
http://ourworld.compuserve.com/homepages/dp5/cosmo.htm

Chantal
kjw
korosten, there a some issues with tired light. here are some

http://www.astro.ucla.edu/~wright/tiredlit.htm

http://en.wikipedia.org/wiki/Redshift

and the section on Mechanisms seems fairly well grounded in its claims. it is only gravitational redshift that does not rely on the distance between the source and detector to increase.

its a good topic you have started.
korosten
I just ordered the book "Seeing Red: Redshifts, Cosmology and Academic Science" by Halton Arp - I want to know it! ;-)

He studied quasars etc and red shifs, and supposedly found gazillion discrepancies with the idea that redshift = just doppler effect.

I am not advocating the tired light theory. But, maybe there is another effect we simply don't know yet.

After reading a lot of stuff, it just seems like all the things needed to make the big bang and redshift=doppler effect consistent are getting a bit too unreal for me - and maybe accepting that we may simply not know why the light is redshifted the way it is would explain things better.

It's funny, because before this thread :-), I have been a FIRM believer of the big bang theory, NEVER questioning it at all!

But, I thought the big bang theory was based on a lot MORE than just this redshift! That's why I am so skeptical now! I was initially just curious as to why we think SPACE is expanding. Then I wondered if the big bang was consistent with black holes (wouldn't we be in a black hole if there WAS a big bang) etc... and all this inflation and dark energy...?

Anyway :-). Let's keep discussing! I am not saying there was no big bang, but I think as a good scientists, we should question all theories!

Chantal
kjw
QUOTE
korosten Posted on Today at 10:37 AM
wouldn't we be in a black hole if there WAS a big bang

what has lead you to that conclusion ?

fizzeksman
Chantal
QUOTE
fizzeksman,

My post was in regard to your reference to "dark energy" and the idea that there might be another plausible explanation for observed phenomena including redshift.

Chantal
QUOTE (->

My post was in regard to your reference to "dark energy" and the idea that there might be another plausible explanation for observed phenomena including redshift.

ChantalFrom what I know, the current theory is some "dark energy".

It seems weirder and weirder the more I think about it :-). All this, *space* that is expandng, dark energy, acceleration, inflation that is supposed to have different speeds different at different times, all just to explain this redshift that is a doppler effect?

What *if*, just as thought experiment, there indeed was another explanation for redshift (just IF). What if redshift did NOT mean galaxies moving away.

Cheers

This doesn't mean I am trying to justify cosmic expansion... far from it.. being a viewpoint I totally disagree with.

.
korosten
More thoughts ;-)

I read a lot about tired light, and it sounds to me like we don't really know another effect (yet) that seems really plausible/scientifically sound. BUT:

Supposedely these galaxies move away from us at close the speed of light (or even more!?). Doesn't that mean that SR has to be considered, and the time dilation? So a huge redshift would NOT mean velocities > c, but in fact, when SR is considered, it would NEVER be more than c?

I often see the balloon analogy as proof that SPACE expands vs matter.
People then make examples of someting exploding, and that we would have to be at the center if everything would move away from us.

Now, let's assume at least SOME of the redshift is indeed the doppler effect. Isn't it still possible to have a "BB", but with MATTER expanding and not SPACE?

Imagine a much larger explosion - say the earth. Imagine we are sitting on a little piece close to the egde (NOT close to the center).

When we would look around us (say a few feet), all pieces would seem to fly AWAY from us, *including* pieces closer to the center! And if we couldn't see all the way to the center - imagine we could only see a few feet - then wouldn't it look like all pieces woudl move away from us at roughly the same speed? I'm sure that could be computed :-).

I just feel like that assuming SPACE expands, and that SPACE can magically have expansion speeds of v>c seems odd. So we can just *ignore* special relativiy for galaxies that move away from us, becaus they are are not REALLY moving, but SPACE is?

Chantal :-)
kaneda
korosten. Of course space has expanded from a point source to tens of billions of light years across, starting at 10^20 times light speed, then magically slowing down below light speed then speeding up again. And this all happened without any change in the structure of space without any change in the natural laws of the Universe.

And Peter Pan still lives in Neverneverland with Tinkabelle.
korosten
:-)
Or maybe we are all just a computer simulation with some issues :-)

Chantal
kjw
QUOTE
korosten Posted on Today at 1:25 AM
Supposedely these galaxies move away from us at close the speed of light (or even more!?). Doesn't that mean that SR has to be considered, and the time dilation? So a huge redshift would NOT mean velocities > c, but in fact, when SR is considered, it would NEVER be more than c?

i thought this too. if SR kicked in we should see these galaxies stop moving ie through time dilation, but you need to go a bit deeper and think about this ...

If something is coming towards you at nearly the speed of light and you measure its apparent speed without taking into account the diminishing time it takes light to reach you from the object, you can get an answer which is faster than light . This is an illusion and is not due to the object moving at s>c

http://math.ucr.edu/home/baez/physics/Rela...perluminal.html

what is wrong with the assumption that space expands ? sure GR predicts singularity which in turn makes itself redundant, but what other explanation is currently plausible that is backed up with experimental evidence ? our understanding of the nature of the universe will change, but this is not because current theories are wrong, its just because current technology has limits. these limits will increase allowing far greater experiments. experiments change theories, theories should not be allowed to change theories.

a computer simulation theory is no good either, its self defeating. for that means we will never have the ability to determine what realitiy is or if this reality is real. you can never prove we are in a computer simulation if we are a part of the simulation.

fizzeksman

Chantal

The technical difficulties presented in trying to prove/justify an expanding universe are almost beyond comprehension. Consider the following:

If space is expanding.... where is it expanding to?

What and where is the energy that drives the expansion?

Do we have to create a new name and characteristics for the void that our expanding space is eventually going to displace?

In the visible universe we are familiar with "Super Novas". These theoretically occur when stars (suns) become too massive. With the energy and mass of billions or perhaps trillions of stars in the universe would not the mass/energy density in pockets have reached critical "Super Nova" density long before all the mass/energy could have accrued in a singularity?

If the universe and everything in it is expanding proportionally we have no way of ever proving or disproving the fact because all the possible forms of measurement are expanding as well. The only recourse would be to wait around for perhaps a few trillion years and watch what happens. This would make it a moot conjecture similar to the question of: "How many angels can dance on the head of a pin?"

The true nature and beauty of our universe lies not in its complexity, but instead, in its' simplicity.

Consider that the universe as we know it is comprised of two basic elementaries...that of space and energy. Three if you wish to include the man-made concept of time.

Space you are familiar with as volume... that in which all else is contained.
Energy in its' most basic form is only kinetic/inertial space in motion.

Everything else builds up from these two or three constituents, simply for some and more complicated for others, as cause and effect.

.
korosten
QUOTE (kjw+Nov 30 2006, 08:32 PM)

what is wrong with the assumption that space expands ?

Exactly, it would be an illusion. Maybe the astronomers DO consider that, but it sounds like not from what I often read when they talk about speeds > c...

I tend to prefer the simplest solution that explains everything.

Having to add the "space expansion", and inflation, and dark energy, etc, et , seems like a lot o things to add just to explain that redshift=velocity (seems like cheating a bit to me :-).

I think you can explain *everything* by adding more dimensions, and other hypothetical things.

So, I think it would be much better if we could explain things *without* the need of these things!

Isn't it MAYBE thinkable that the redshift is NOT ONLY the doppler effect, but other things, compared to having to "invent" all these hypothetical things???

(In addition, if space expands - as fizzeksman said, what into? )

(PS: I was just joking about the computer simulation!)
korosten
QUOTE (fizzeksman+Nov 30 2006, 08:51 PM)
If the universe and everything in it is expanding proportionally we have no way of ever proving or disproving the fact because all the possible forms of measurement are expanding as well.

We can.. sort of: when looking far away, we see into the past.

However, interestingly, people who think space expands, think that the matter in it does NOT expand! That's what I think is also strange.

So then, what exactly is "expanding?!". Isn't that ultimately not the same as "matter is flying away from each other" :-) ?

(Except, that they allow space to expand with v > c !!)

Chantal
kjw
okay lets go with this....

so all matter is moving through space, this movement is accelerating. this acceleration is not bound by SR. for some reason accelerating galaxies can ignore SR. using observational evidence and extrapolating backwards in time, and considering space has always been here, then there should be a region in space where all matter and energy originated.

questions:

how do galaxies ignore SR ie what happened to time dilation, mass increase and length contraction ?

where is the region in space that all matter and energy originated ?

has space always been here or was it created also ? ie was space created befor matter and energy was created ?

what energy source gives matter is acceleration ?

i think it is more complicated to assume space was not created at the time matter and energy was. because the question of when was space created is not answered.
korosten
I am not sure which questions you are asking me?
(Especially because I assume that SR IS correct as well as GR and we DO have to consider that - that was one of my complaints about the expanding space :-)
Chantal
kjw
hello korosten

I am not questioning you directly. I'm questioning the idea you have of matter expansion vs space expansion

the expansion of space is compliant with SR

the idea that galaxies are traveling through space is not compliant with SR

these two opposing ideas is what I thought your post was addressing.

I am saying that it is not only redshift that gives rise to the idea that space is expanding but that space expansion does not violate SR. Whereas the movement of matter through static space can fit with the idea of redshift but the movement of matter through space some how escapes the effects described in SR. Since you accept SR you can throw away the idea of matter moving through space.

The questions I posted are questions that need answering by those who do not accept that space expands

korosten
QUOTE (kjw+Nov 30 2006, 10:38 PM)
hello korosten

I am not questioning you directly. I'm questioning the idea you have of matter expansion vs space expansion

the expansion of space is compliant with SR

the idea that galaxies are traveling through space is not compliant with SR

these two opposing ideas is what I thought your post was addressing.

I am saying that it is not only redshift that gives rise to the idea that space is expanding but that space expansion does not violate SR. Whereas the movement of matter through static space can fit with the idea of redshift but the movement of matter through space some how escapes the effects described in SR. Since you accept SR you can throw away the idea of matter moving through space.

The questions I posted are questions that need answering by those who do not accept that space expands

kjw,

Ok: assuming space does NOT expand:

1. if we accept SR, then the *apparent* velocity through a redshift is NOT the actual velocity of the object. Why? Because of time dilation. So even an infinite redshift would mean v < c.

2. How are galaxies traveling through space not compliant with SR? I did not understand that.

3. The weird point is the opposite (as I tried to say before): people who think SPACE expands, simply assume that space can expand FASTER THAN C!
That is what I could call a violation of SR... :-)

Chantal
fizzeksman
KJW
QUOTE
The questions I posted are questions that need answering by those who do not accept that space expands

KJW.... What in your model produces "SPACE".. that which defines volume in three dimensions (you know that stuff between us and the stars, also the same as the "space" you would have expanding) either in minor or voluminous proportions?

.
kjw
korosten - using this quasar

http://www.space.com/scienceastronomy/astr...sar_000413.html

and Hubble's law, I calculate its recessional velocity as 213 million km/s which is 710c

now if this quasar is moving through static space at 710 times the speed of light certainly you accept that this is an example of how galaxies traveling through space is not compliant with SR

If my calculations are correct then the only way we can explain this is if the space between the quasar and earth is expanding

QUOTE
fizzeksman Posted on Today at 10:39 AM
KJW.... What in your model produces "SPACE"
its not my model. Its the big bang theory that says space, time, matter and energy were all created at the moment described as the big bang.

korosten
QUOTE (kjw+Dec 1 2006, 01:44 AM)

http://www.space.com/scienceastronomy/astr...sar_000413.html

and Hubble's law, I calculate its recessional velocity as 213 million km/s which is 710c

That is the whole point!

It is all based purely on the REDSHIFT?!

Don't you see?

So you really think that the redshift corresponds not only to an APPARENT velocity, but to a real velocity? WIHTOUT considering
1. other reasons for SUCH an enormous redshift
2. not considering that this huge redshift does NOT mean 750 c, but if you include SPECIAL RELATIVITY, then you would come to a number SMALLER than c
(don't know the formula - does anyone know???)

Chantal
korosten
More :-)

...and note that Hubble HIMSELF was skeptical that this really means a *REAL* Velocity. That's why he also called it an *apparent* velocity.

Chantal
kjw
I agree it is an apparent velocity because matter can not travel at such speeds, but if you think that if space expands then whats wrong with 710c. it fits quite well.

sure if some time in the future we have new technology or evidence that allows us to challenge this then bring it on. I accept that one day I'll have to re-define what the nature of reality is. but until then what I do not understand is why a persistent search for answers when a fairly logical and scientific explanation already exists is worth our time.

i have considered other reasons for such an enormous redshift, and personally none seem to make any more sense.

why should we not believe Hubbles Law ?
korosten
Of course I do "believe" in the hubble law! It's an observation, and very well verified!
The law ONLY says that there is a relationship (almost linear) between distance and redshift.

It does NOT say that the redshift means a non-relativistic doppler effect! It does not say that the redshift means anything with regards to velocity.

How can I be clearer?

Here is a link to the relativistic doppler effect

http://en.wikipedia.org/wiki/Relativistic_Doppler_effect

So, the formulat to compute the speed, is NOT simply z * c (where z is the redshift),
but instead includes a relativistic term.

Now, please calculate your speed again using the RELATIVISTIC formula, and tell me what you get ;-).

You will get a speed v < c.

Chantal
Nick
Galaxy clusters are not moving through preexisting space away from one another. The universe is the surface of an expanding hypersphere. So space stretches in between large scale objects such as galactic clusters.

It then is not velocity that accounts for the Hubble redshift but the stretching of space. Light traversing expanding space is red shifted by the phenomenon.

Mitch Raemsch -- Light Falls --

daremo shirinai

I also have a question that I think relates to this topic on the nature of spacetime. I studied the social sciences and am a newcomer to physics so please bear with me. My question concerns this: how is it that we can see the past as manifested in the light given off by the big bang just now reaching us through our deep space telescopes if nothing can travel faster than light? Would not that light have already bypassed our occupied region of space given that it happened so long ago and given that nothing can travel faster than light? Or do different spectrum gradations of light have variable speeds? Visually speaking, wouldn't that initial light light have remained at the "crest" of the creation of matter, spacetime, etc which the big bang created? How can we occupy a region of space in which we can just now observe this light if space had not existed before it? Am I missing something or, no doubt, misunderstanding the nature of these observations? Is this light from deep in the universe that supposedly lets us observe some of the initial moments of creation just the residue of the big bang and if so how long does this residue last?
kaneda
Nick. Evidence for a hypersphere is....?

Evidence of extra dimensions is.....?

How can space stretch endlessly?

How does space have a gravitational effect on matter as it expands? Surely the space all around matter would have just as much effect so why should matter be forced to move with the expansion? Is matter just an effect in the structure of space (as in the aether theory?)

If you stretch light, by stretching the space it is travelling through, then it will make the waves longer, so red-shifting it.
korosten
QUOTE (Nick+Dec 1 2006, 04:59 AM)
Galaxy clusters are not moving through preexisting space away from one another. The universe is the surface of an expanding hypersphere. So space stretches in between large scale objects such as galactic clusters.

It then is not velocity that accounts for the Hubble redshift but the stretching of space. Light traversing expanding space is red shifted by the phenomenon.

Mitch Raemsch -- Light Falls --

Nick,

Yes, that make sense. If you assume that indeed, space is expanding, that would be the explanation and I have no problem with that. And then of course you would NOT use ths SR to compute the speed, since the galaxies were not really moving relative to each other.

BUT, my question was: how can we *conclude* in the first place, that indeed SPACE is expanding?!

2 questions to that:
1. assume for a moment, space was NOT expanding, and indeed, the galaxies were MOVING away. I assume, we would then need to use the *relativistic* doppler shift formula to compute their speed, which would always be < c, right? Since they would be moving relative to us.

2. assuming that SPACE was expanding: how exactly would that work? I would assume then that everything, including atoms, photons, planets, galaxies would get bigger and bigger, right (or were smaller in the past)?

Chantal

korosten
Here is an excellent, detailed document about the redshift:

http://arxiv.org/PS_cache/astro-ph/pdf/0310/0310808.pdf

(it is a traditional, mainstream explanation).

However, what I found interesting, that the recent supernova time dilation studies is consistent in BOTH views, whether we see SPACE as expanding and use GR, or if we consider space NOT expanding (and things have speed) and use SR.

SO, it seems that the ONLY indiction so far that SPACE is indeed expanding is the magnitude study of supernovas... (and I'm not sure how solid that is?)

Chantal
Nick
QUOTE (kaneda+Dec 1 2006, 03:20 PM)
Nick. Evidence for a hypersphere is....?

Evidence of extra dimensions is.....?

How can space stretch endlessly?

How does space have a gravitational effect on matter as it expands? Surely the space all around matter would have just as much effect so why should matter be forced to move with the expansion? Is matter just an effect in the structure of space (as in the aether theory?)

If you stretch light, by stretching the space it is travelling through, then it will make the waves longer, so red-shifting it.

Kaneda. It is the absolute form of Einstein's Closed; finite yet unbounded universe. It started with Einstein's cosmological theorem; that the universe could curve back on itself.

Mitch Raemsch -- LIGHT FELL! --

Nick
QUOTE (korosten+Dec 1 2006, 03:21 PM)
BUT, my question was: how can we *conclude* in the first place, that indeed SPACE is expanding?!

2. assuming that SPACE was expanding: how exactly would that work? I would assume then that everything, including atoms, photons, planets, galaxies would get bigger and bigger, right (or were smaller in the past)?

Chantal

Otherwise they must be moving away from each other through a preexisting INFINITE space.

The stretching is at all scales. Larger distances create larger stretches. It appears that the STRETCHING is increasing also. It only becomes observable at larger scales.

Mitch Raemsch -- Light FELL! --

korosten
So I found out (via another forum :-) that matter indeed would NOT expand even if SPACE would expand - otherwise physical constants would change and it can be proved that they do not change.

1. Space expansion:
------------------
So given that the objects do not change in size as space expands, then how is matter "dragged" along space as it expands?

I don't understand how matter would then be connected to space, if the size of the matter does not change. At what places does matter "slide" along space so to speak, and at which places is matter "connected" or "hooked" up to space?

If this is a force that acs on the *matter*, then, the objects should actually move within its space and have velocity (thus the SR version would be true).

Otherwise, if the force acts on *space itself* and NOT matter, then I don't understand how objects in that space can be dragged along it (but at the same time, matter keeping its size).

2. GR explanation of redshift.
---------------------------
Could the redshift also be explained - consitent with GR - as BENDING of space (rather than expansion?) Like Gravity bends space?
(Example: redshift close to a massive object such as a BH).

If we imagine - just for a moment - that space is actually a "sphere", so space would be bent more and more the further away we got, wouldn't we observe exactly such a redshift??? And the redshift would be a function of distance from earth!

So that way, the redshift would be consistent with:
- a finite universe (closed)
- that does not necessarily expand :-)
- and objects inside would not be moving at v >c :-)

(I am think of the earth= flat -> earth is round analogy ;-).
Chantal
mott.carl
i think that the universe is a hypersphere with infinities curvature9foliations)
that go if extended until the infinite,then the bodies go increasing its velocities in the rates in that the curvatures go if turning flats.then the space-time and it topology and matter go if expanding until the infinite,and the BH are singularities
of the space-time in remote past.imagine the space-time with "kinks" in it tissues
that id expanding in the same proportions,without "ruptures" in the space-time,conserving the topology.
Nick
SINGULARITIES DON'T AGE.
kjw
QUOTE
Nick Posted on Today at 8:13 AM
SINGULARITIES DON'T AGE

why not ?
Montec
Hello all

Can anyone tell the difference between space expanding and the rate of time flow increasing? Both will result in red shifting of light.

kjw
QUOTE
Montec Posted: Today at 10:42 AM Report this post ·
Can anyone tell the difference between space expanding and the rate of time flow increasing

expansion of space results in redshift and blueshift (motion in all directions)

an increase in rate of time would only lead to blueshifts, unless you are saying that the rate of time in general is increasing then no one could tell.

what are your thoughts or is the question rhetorical
Montec
Hi kjw

Light from a gravity well is red shifted. IE from a slower time (in the gravity well) to a faster time (out of the gravity well). There is a time flow rate change going from high gravity to low gravity. The universe as a whole is loosing mass from the conversion of mass to energy in stars. There is a direct correlation between mass and the rate of time flow. Therefore the the time rate for the universe as a whole should be increasing. The speed at which the rates propagate away from the clumps/groups/clusters/galaxies of matter is unknown (speed of light?).

In any case the light emitted in the far past will be red shifted (slower time to a faster time) and it will not matter in which direction we look because in any direction we will be looking into the past. There is no center of red shift caused expansion. If the rate of mass conversion increases then the change in the time flow rate will also increase for that area of space.

This is one possible explanation of red shift that fits the observed universe.

korosten
I thought matter AND engergy both bend spacetime equally ;-).

Otherwise that would be a great explanation!

I think the bending of space - no matter what its' cause, should cause a redshift, right?

The bending of space could be in the past, or in the distance! In both cases, it would create a redshift.

So I wonder if there is ANY solid evidence that the redshift REALLY means EXPANSION?

Chantal

Nick
QUOTE (kjw+Dec 5 2006, 12:16 AM)

Nick Posted on Today at 8:13 AM
SINGULARITIES DON'T AGE

QUOTE
why not ?

Nothing more happens.
Gravitational singularities are the End of Time and Space.
But their infinities in curvature make them nonsense.

MITCH RAEMSCH -- LIGHT FELL AGAIN --
kjw
oh got you, I thought you meant that if there was a singularity sitting on my desk that it would not age, but what you are saying is that "within" a singularity there is no time, to which I would agree ....
Nick
QUOTE (kjw+Dec 5 2006, 02:26 AM)
oh got you, I thought you meant that if there was a singularity sitting on my desk that it would not age, but what you are saying is that "within" a singularity there is no time, to which I would agree ....
\
If time stopped for how long would it stop?
There can be different timerates for everything in the universe BUT ONLY ONE NOW.

Also this is the secret to SPACE-TIME TRAVEL. If your spaceship is moving near lightspeed then its clock is running several times slower than light's and therefor it can go farther than light can by light's clock.

If your clock goes slow then your motion will be apparently increased by THE GAMMA FACTOR. Also EVERYTHING ELSE AROUND YOU WILL APPEAR TO BE SPED UP IN THEIR MOTIONS. Relative motion can appear INFINITE.

Mitch Raemsch -- Light Fell --
Montec
Hi korosten

I'm not sure what you mean by energy?

If energy is EM radiation which is composed of photons which are bosons that can have an infinite number at any point at any time anywhere in the universe which leads to infinite curvature at that point for one brief moment of time and the associated space-time gravitational shock-wave.... hehe got carried away there. The point I'm making is that I am not sure bosons have any affect on space-time curvature or time rate.

I will see if I can find any info on the net to give me a definitive answer on if and/or how energy can bend space-time.

Nick
The first physicists to solve equations for black holes thought they saw MATTER simply DROPPING OUT OF THE UNIVERSE. If space-time ends then so would matter. That is the problem with singularities - inifinite quantities.

Mitch Raemsch -- LIGHT FELL ALWAYS --
kjw
QUOTE
Montec Posted on Today at 11:36 AM
Light from a gravity well is red shifted. IE from a slower time (in the gravity well) to a faster time (out of the gravity well).
this makes perfectly good sense. thank you for the correction.

are you saying this explanation could be used to favour the mis-interpretation of redshift = space expansion ? could you please explain your response.

Nick
QUOTE (kjw+Dec 5 2006, 03:39 AM)
this makes perfectly good sense. thank you for the correction.

are you saying this explanation could be used to favour the mis-interpretation of redshift = space expansion ? could you please explain your response.

Let me interject: light is Redshifted at emission in gravity's slower time. This is known as the Einstein Shift. There is no tired light.
General Relativity conserves energy. If light is redshifted it started out that way. Curvature does not change the energy. CONSERVATION OF ENERGY.

Mitch Raemsch -- Light FELL ALL THE WAY --
Montec
Hi korosten, kjw ,et al.

korosten
The only energy I could find that can be linked to gravity is stress-energy.
See here : http://en.wikipedia.org/wiki/Stress-energy_tensor
There is some discussion of zero-point energy in the links around this topic and the problems with QM and GR relating to zero-point energy. I could not find any link that explicitly links EM radiation and the above stress-energy tensor.

kjw
Yes, time shifted light may explain the red shift of distant light sources. If the rate of time flow at the point of emission is not the same time flow at the point of reception then the light will exhibit a frequency shift. Slow time to fast will give a red shift. Fast time to slow will give a blue shift. An increasing rate of time flow for the universe would cause a red shift that increases the farther you go back in time (distance). The only method I could see that would cause a change in the rate of time flow was the removal of mass from the universe. Stars convert mass to EM radiation and EM radiation, as far as I've been able to research, does not affect the rate of time flow.

korosten
Montec,

Thanks for the info. this is so cool! So we have at least 4 valid explanations for redshift, that are all compatible with the observation that distant supernovas show a
*time dilation*!!!

1. Time might have run slower in the past (for whatever reason)
2. Space may be bent in the distance (for whatever reason - see below)
3. Space may be expanding (big bang)
4. Galaxies may be flying away (big bang related)

All 4 should be consistent with the observed redshift (please correct me if I am wrong!!!

Now, As for the *reasons* whey space is bent or time ran slower:
- maybe there are other ways spacetime can be bent, not only gravity
- maybe there was indeed more matter in the past
- maybe space is simply bent! (Sphere?) (WHY NOT???)

Anyone disagree with any of this? Does anyone have any proof that would exclude one or the other?

Chantal
kjw
hello korosten and Montec,

to challenge this we would need

a - define the assumption that redshift is caused by gravitational difference between source and earth, not that space is expanding

b - a selection of objects whose properties are know and relevant to our question ie massive objects, observed redshifts etc

c - someone who has the mathematical expertise to determine what is the theoretical redshift based on gravitational effects using relativity,

d - a comparison of these theoretical gravitational redshifts with the observed measured redshifts of the objects mentioned in b

e - or a paper that has already done the above.

now I do not know how to calculate point c ,

but I would certainly be able to spend some time gathering, b, d and e if we decide that point a is properly defined and worth while
korosten
Cool!

I am happy to help out (not with the math, unfortunately), but with searching.

Now, I just wanted to make sure we also consider the possibility that there may be another reason why space is curved.

Maybe we can at least determine the "curvature" of spactime given the observed redshifts.

We could also determine how large the "time dilation" effect would be, to see if it is truly compatible with the observed supernova time dilations (and possibly other observations).

Then, we could determine how much "mass" would be required for this curvature - again, considering that other (maybe unkonwn) effects could cause it (I still think there is the possibility that this is simply the "structure" of our space?).

Chantal
kjw
great

we should get some independent information and post it in a few days for group verification and then discussion

Nick
Quasars or quasi stellar objects are seen to be compact. This might imply a strong gravitational field.

Mitch Raemsch -- Light Falls --

kjw
good call, thanks Nick
kjw
hello korosten

with regards to :

QUOTE
kjw Posted on Dec 6 2006, 09:54 AM
a - define the assumption that redshift is caused by gravitational difference between source and earth, not that space is expanding

In gathering information that we decided we needed I saw that the information we need will change if the assumption is not exactly defined.

Do you agree that the objective is to "gather data to make an assessment that redshift is due to gravitational effects only. therefor the most massive objects should have z>0 and when listed in increasing order of mass the objects respective redshift will also be in an increasing order."

korosten
Well, what we know for sure is that the redshift gets larger as a function of the distance (in most cases).

We also know that it cannot be simply gravity alone, as people have estimated the mass of galaxies etc and the redshift does not match that.
But it could still be that spacetime is *bent* in the distance/past for whatever reason.

We also know that certain objects like quasars seem to have a much larger redshift than they should if redshift would simply mean distance (so yes, gravity is probably an important factor there?)

What we could propose is that the redshift is caused by either:
- bending of spacetime (whether caused by gravity OR OTHER reasons - gravity alone will most likely not explain it!), which is a function of the distance OR time. O

- that time may have run slower in the past for other reasons than bending of spacetime.

Chantal
korosten
- yes we should find greater redshifts for more dense and more massive objects
- but that *alone* will not explain why there is more redshift in the *distance* (and/or past)

Chantal
Nick
If space expands then light traversing this space is also being expanded. This is the surface of the hypersphere growing.

MITCH RAEMSCH -- Light Falls EVERYWHERE --
korosten
Nick,

Yes, I know.

But what if the hypersphere were NOT growing. Wouldn't we still observer the time dilation and redshift? ANY curvature of spaceTIME would result in changes in time/light shifting (depending on the type of bending)

Chantal
Nick
We would only see the gravitational time redshift yes. This is known as the Einstein Shift.
korosten
... could you please elaborate? What would then *not* fit into this theory?

(Given that there may be *additional* reasons for the bending besides the observed mass of galaxies!)

And what do *you* think about all this?

Chantal
Nick
This should have been said Korosten along time ago on this thread. We know that the universe is expanding because if it wasn't it would be contracting due to its gravity. Einstein invented the Cosmological Constant to balance the gravity of the universe with outward force; to keep the universe static Neither expanding or contracting. Later he considered it the biggest blunder of his life. This is the proof Korosten.

MITCH RAEMSCH -- LIGHT FALLS --
4Dguy
Nick,

QUOTE
This should have been said Korosten along time ago on this thread. We know that the universe is expanding because if it wasn't it would be contracting due to its gravity. Einstein invented the Cosmological Constant to balance the gravity of the universe with outward force; to keep the universe static Neither expanding or contracting. Later he considered it the biggest blunder of his life. This is the proof Korosten.

You are using circular reasoning for your argument, that is not a proof.

Nick
What is the circle?
4Dguy
Nick,

QUOTE
We know that the universe is expanding because if it wasn't it would be contracting due to its gravity

This is circular reasoning.

This is what you are discussing right now. If you have a unshakable belief that the universe is expanding you will see anything that agrees with you as proof. Expansion or contraction may not even be an issue depending on what is found for the red shift between galaxies. I have read all the discussion in this thread and found most of the people here open minded with a co-operation that looked like it was combining forces to look for possibilities into the reasons for anomalies of observations to current theories about a big bang. You jumped ahead and said I am right and here is the proof. Not only was it not proof it tends to short circuit the evidence gathering portion of the discussion. I am interested in their thoughts and the process they and you have started. Keep gathering for each idea and than discuss the merits of each one.
Nick
I am right. AND I have provided the proof.

IF the universe isn't expanding IF it was STATIC gravity would take over. We would be headed For A BIg Crunch.

The proof is in the pudding!!!

MITCH RAEMSCH -- LIGHT FALLS --
AmazedByThis
Chantal -
You asked "How do we know that *space* is expanding?, ... and not just the matter in space?"
What is space? Is it not the area that contains that matter of the universe? Does space exist beyond the edges of matter? We cannot go outside the edge of matter because we are matter. Nothing observable (energy) can come to us from outside the edges of matter, because what would it come from? Isn't saying that space is expanding the same as saying that the distance between galaxies is increasing?
(Note: I'm not claiming everything I'm stating is true. I'm wondering about whether my statements are true.)
korosten
Nick:

This is no proof, it is a (logical) argument.

A proof that I can accept would be:
- observations that match a theory very well and have no other explanations.
- or the opposite: observations that are not explicable by the current theory.

So, saying that the universe would collapse is just *yet another* theory, and not an observation. yes it would be a logical conclusion if we were certain that all other aspects of our cosmology theories were proven, but so far, it isn't. What is the proof that

a) gravity truly acts all the way to "infinity" (or even billions of light years). Does it really? Maybe the force has a limit to its range despite the "mathematical formula"?

b.) that there isn't another force (such as that weird dark energy - which I don't believe in so far)

It would be really great if we all could work as a TEAM to find the TRUTH! I think with the internet this could be possible!

Chantal
korosten
Amazed:

I think they are very different.

If SPACE is expanding, the galaxies might not even have a large VELOCITY away from us.

if the DISTANCE as we normally measure it would get greater, the galaxies would have a VELOCITY away from us.

It is a huge difference in the way we picture the workings of the universe/space/time.

That is one of the "issues":
- if redshift=VELOCITY (doppler), then the galaxies move away with an *apparent* velocity >>> c
- if redshift=expanding SPACE, then the galaxies do not move much. Instead, SPACE would be expanding at a "velocity" (that term doesn't even really make sense for space)

Chantal
N.U.R
"Mummy why do my Rices go snap crackle and pop"?

QUOTE (Zephir+Nov 28 2006, 10:52 PM)
By AWT, in the interior of super-massive black holes, and the expansion of cereal  is in fact the manifestation of gravitational collapse of such black holes and gradual increasing it's density and temperature (the overall speed of energy spreading slovens in the bowl).

By such way, the Rices don't Snap, Crack or Pop, they collapses instead with increasing speed
like common Frostys, which can explain the dark milky Coco Pops phenomena.

AWT, is there anything it cant explain?

N.U.R
4Dguy
korosten,

Montac had an Idea that maybe the red shift had a inherent optical solution. We know the more mass the slower time runs. The reverse is also true the less mass the faster time runs. Light leaving a galaxy goes through a lens. That lens is the boundary effect that mass has on space. Astronomers use it to view galaxies behind other galaxies as a magnifying glass. As it leaves the boundary the leading edge of the light would accelerate possibly before the tailing part of the light was through. If in the distance between galaxies the speed continued to increase light would continue to be stretched. Since we live on the outer portion of our galaxy the compression of that light might not be equal to the stretching so every thing appears to be red shifted. If we lived in the center of our galaxy we might not see the universe as expanding.
Nick
Korosten. No. It is proof by logical deduction. Einstein's gravity shows this. The universe can't be STATIC. It can only be expanding or contracting. Perhaps you believe space is INFINITE. That is a falacy. It has a beginning. It needs to be created by GOD.

QUOTE (Korosten+)
It would be really great if we all could work as a TEAM to find the TRUTH!

Get over it. The truth is ALREADY proven SHANTY.

MITCH RAEMSCH -- LIGHT FALLS ON ZEPHIRS HEAD --

4Dguy
Nick,

Is the solar system expanding?
korosten
Nick,
If you are so certain, then why even discuss it with us!

Note that I never claimed the universe was NOT expanding. At this point and am simply trying to figure out what the REDSHIFT means... one step at a time. Maybe it turns out you are right... but maybe not.

How about we meet back here in say... 20 years (1.1.2027 for instance) when we will hopefully know), and THEN we 'll talk again about what truth is ;-).

Re optical solution:
The optical solution seems worth investigating to me - in more than one way.
It's known (and easily verifyable!) that light bends when the medium gets denser, say in water or glass, so you would observe a redshift if light were to pass through such a medium with changing density (refraction?).

If we imagine (for a moment) that there WAS some light carrying medium, instead of a void (that we have not detected yet), which was attracted by gravity as well, then that medium would be denser around massive objects, hence bending light...

Chantal
4Dguy
korosten,

QUOTE
If we imagine (for a moment) that there WAS some light carrying medium, instead of a void (that we have not detected yet), which was attracted by gravity as well, then that medium would be denser around massive objects, hence bending light...

Yes ,thats how it might look on first glance but the observations of GR and SR suggest that the medium becomes less dense. The Lorentz transformations suggest that the light expands in the presence of mass. That would suggest that the medium is expanding. That would also suggest that the medium is denser and more energetic in space.
korosten
One theory that might explain the redshift is the plasma theory:

http://www.plasmaphysics.org.uk/research/redshift.htm

Basically hot charged particles in plasma (around stars etc) can cause a redshift, which would explain the cosmological redshift and redshift of quasars.

Does anyone have a background in plasma physics who could read this link and verify that it is solid science?

Chantal
Montec
Hello all

If time flows more slowly around mass then the microwave background radiation should be blue shifted (faster time to slower time) from areas of the sky that have little or no mass with respect to us. I'm still looking into this idea so don't take it to the bank yet.

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