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Author Topic: Can we measure 'expansion'  (Read 29388 times)

lyner

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Can we measure 'expansion'
« Reply #25 on: 14/03/2009 20:04:42 »
Is the Hubble constant big enough to get a measurable amount of expansion within a galaxy? Someone do the sums for us please - I'm off up to have a bath 'cos I stink of fibreglass resin.
 

Offline Vern

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Can we measure 'expansion'
« Reply #26 on: 14/03/2009 22:46:28 »
I found this calculator Now if we can get a good translation of the units they use into the units we know about, we might just be able to get a number.
 

Offline yor_on

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Can we measure 'expansion'
« Reply #27 on: 14/03/2009 22:54:29 »
Way to go Vern :)
 

Offline DoctorBeaver

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« Reply #28 on: 14/03/2009 22:58:04 »
That calculator is gibberish!  ???
 

Offline Vern

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Can we measure 'expansion'
« Reply #29 on: 14/03/2009 23:10:17 »
Here's the home page of the calculator. It seems legitimate. Dr. Chris Haines seems to be a Phd working in a graduate school in Italy.
 

Offline yor_on

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Can we measure 'expansion'
« Reply #30 on: 14/03/2009 23:19:44 »
It is certainly not easy from a layman perspective :)

------Quotes--

Omega_M ~ M/L x j/\rho_c, where M/L is the field mass-to-light ratio, j is the field luminosity density and rho_c is the closure density. A wide range of potential systematic effects are explicitly controlled by independently deriving the mean cluster mass profile (finding good agreement with theoretical predictions), the cluster light profile, the redshift evolution of both cluster and field galaxies, the differential evolution between the two, and the field and cluster efficiencies for the conversion of baryons into galaxies

We conclude that Omega_M=0.19 +/- 0.06 where the errors are objectively evaluated via resampling methods. The redshift evolution of the numbers of clusters per unit co-moving volume over the 0 <= z <= 0.6 range is found to be very slow, as is required for consistency with a low density universe. The evolution of galaxy clustering in the field is compatible with a low density universe, and strongly disfavors models of galaxy evolution that associate low density halos with individual galaxies.

http://arxiv.org/abs/astro-ph/9711272

---------

Lambda: A constant term (labeled Lambda) which Einstein added to his general theory of relativity in the mistaken belief that the Universe was neither expanding nor contracting. The cosmological constant was found to be unnecessary once observations indicated the Universe was expanding.

As for that equation  ' H0 ( km s-1 Mpc-1 ) '
You better read this first :)
http://books.google.se/books?id=wgOYbScwi-cC&pg=PA373&lpg=PA373&dq=what+is+H0+(+km+s-1+Mpc-1+)+astronomy&source=bl&ots=6Z4OyVPseX&sig=_tcyQj6CFniP-mN43FCx9X6PNKE&hl=sv&ei=pyy8Sfq7B5GJsAaPkrzpDg&sa=X&oi=book_result&resnum=2&ct=result

And Look back time http://www.iop.org/EJ/article/1538-4357/619/1/L103/18425.web.pdf

The phenomenon that, owing to the finite velocity of light, the more distant an object being observed, the older is the information received from it. A galaxy one billion light-years away, for instance, is seen as it looked one billion years ago.

--------End Quotes.........

Ah, are we ready to calculate now?
« Last Edit: 14/03/2009 23:30:17 by yor_on »
 

lyner

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Can we measure 'expansion'
« Reply #31 on: 15/03/2009 00:06:09 »
Well, I'll do it, then
The Hubble constant is 72km/s /MPc and the galaxy is about 0.1MPc across.
That means the recession of the most distant stars in our galaxy due to Hubble expansion is only 7.2km/s.
That's very very small wrt c so you will not detect it by red shift.

Even Andromeda which is 0.77MPc away is only  receding at 55km/s due to Hubble.

Red shift is significant much much further away.
« Last Edit: 15/03/2009 00:07:52 by sophiecentaur »
 

Offline DoctorBeaver

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« Reply #32 on: 15/03/2009 00:47:21 »
SC - Andromeda receding? As in Messier 31 Andromeda? Are you sure about that?
 

Offline Vern

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« Reply #33 on: 15/03/2009 02:38:17 »
Quote from: sophiecentaur
Even Andromeda which is 0.77MPc away is only  receding at 55km/s due to Hubble.
But I think Andromedia is approaching us at about 30 km/s and accelerating toward us. And in 15 billion years or so we will be colliding with Andromedia. But the solar system probably can't survive that long.

But I guess the question at hand can't be advanced by the cosmic red shift. I think we were hoping to find some evidence that would help indicate whether our galaxy is expanding internally. It seems that evidence can not come from studies of the local red shift.
 

lyner

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Can we measure 'expansion'
« Reply #34 on: 15/03/2009 09:39:30 »
I said Andromeda is receding due to Hubble expansion- that's nothing to do with how it's moving 'in it's own right'. The few km/s of space expansion is, of course , swamped be the galaxy' a motion. There will be stars within Andromeda which are traveling away from us due to their motion within their galaxy  and objects near those stars which are moving towards us.
The hubble calculation just tells you the expansion of space and the average motion at that distance..

(typo edit - the ipod is too damned smart!)
« Last Edit: 15/03/2009 10:08:28 by sophiecentaur »
 

Offline DoctorBeaver

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« Reply #35 on: 15/03/2009 09:41:12 »
Ah, my apologies SC. I misunderstood what you meant.
 

Offline yor_on

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« Reply #36 on: 15/03/2009 12:22:32 »
DB you say a very interesting thing here.
"The space inside galaxies would expand if gravity were not holding it in check. The force is acting everywhere but in some places is more noticeable as there is less gravity."

What we are getting 'more' of is 'vacuum'.
When we talk about something getting 'more' of something, we usually refer to it in form of density. In this case though we are referring to a 'nothing' getting more. So, by what should we be able to proof the existence of a larger amount of 'nothing'. Yep, that's my thought too, there is only one 'objective' referrer of such a state, namely 'distance'. So are we getting larger 'distances' inside the solarsystem due to expansion? Apparently not, only outside our galaxies.

Now why is it this way? Apparently gravity is thought to be the arbiter of where expansion can or can't place 'new nothings' in our spacetime. Try to consider whether it is possible to place 'nothing at all' beside another 'nothing' and then say that we doubled the amount of nothings:). We know that there exist a vacuum and we know that it has a distance to it. From that view it's not implausible for a new addition of 'nothing' to widen the distances between 'nothings' aka 'vacuum'. But what the heck would that have to do with gravity? Either gravity is a implication of relativity and spacetime, and so is nothing more than the universal 'rollercoaster' acting upon every mass, its 'rides' created by mass in time. Or gravity is a 'force' carried by Higgs 'particles/bosons'. If we accept those ideas then what we call the 'expansion' of 'nothing', as a vacuum in fact is, must be a relation of matter/mass as gravity is created by matter/mass, no matter how one turns it around.

And that makes most sense to me if matter/space would be a symmetry, where you get both for the price of one, so to speak. And in that context the whole idea of distances becomes suspect, as we already know that distance is nothing more than a relation to acceleration, uniform motion, and density, and of course, how the whole idea of placing 'nothing' beside 'nothing' in any way should be able to lengthen a distance :)
 

Offline DoctorBeaver

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« Reply #37 on: 15/03/2009 12:57:08 »
But it isn't "nothing,is it. It's full of virtual particles.
 

Offline Vern

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« Reply #38 on: 15/03/2009 12:58:50 »
Quote from: sophiecentaur
Even Andromeda which is 0.77MPc away is only  receding at 55km/s due to Hubble.
Yes; I noticed that you limited your explanation to -- due to Hubble. and was not confused by it.

The idea that space inside a galaxy can expand, but the galaxy does not expand because gravity overcomes the expansion; that idea seems troubled. What of the behaviour of gravity that might need adjustment so that orbits of heavenly bodies would obediently conform to this new expanded space.

The whole idea of expansion seems a little ad-hoc and not well thought through.
« Last Edit: 15/03/2009 13:01:00 by Vern »
 

lyner

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Can we measure 'expansion'
« Reply #39 on: 15/03/2009 21:25:45 »
I would like to recant my statement about gravity altering things. The fact is that you can allow space to expand at the Hubble rate without needing to modify it due to gravity - unlike gravity, its effect gets bigger and bigger with distance and needn't be considered between stars.

5 am not sure about the `'not well thought out" comment. I'm sure it has had a bit more attention than any of the posted  new theories on this forum. I think the point about space expanding is that space only exists by virtue of the mass within it - as the masses spread out, so does the space.
 

Offline Vern

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Can we measure 'expansion'
« Reply #40 on: 15/03/2009 21:35:18 »
The main problem I have with the expansion theory is the part that allows expanding space to carry matter along with it such that the matter is not constrained to the speed of light. We can never observe that; we can only assume it happens because we know of things that are separated by distances that require faster than light speed to get the separation in the time allotted.

I am inclined to search for some other answer.

I have no problem at all with the notion that space expands because things move further apart. I have a problem with the reverse. Things move further apart because space expands.:) It just seems like a crutch go get around a problem with the big bang concept.
 

lyner

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Can we measure 'expansion'
« Reply #41 on: 15/03/2009 23:24:50 »
Is there a causal 'direction' between the two processes? Why not let them happen together without a `"because"? The "because" could well come from outside the model - in the same way that the BB does.
It seems that, yet again we try to explain things only using familiar terms and find it doesn't work.
Sounds like a cop out, I know, but...
 

Offline Vern

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« Reply #42 on: 16/03/2009 12:32:22 »
It is easy to get side tracked; causality is a side issue; the key issue is; can things in space gain distance between themselves and other things at a greater rate than the speed of light?

This question has great implications. If things can behave in such a way it immediately falsifies the concept: the final irreducible constituent of all physical reality is the electromagnetic field.

That is no small thing. If it is so, it is the first observed reality since Maxwell's postulate, that falsifies that concept.

You can find anything on the internet but it is interesting to see that others are thinking about this.

Bolding is my own.
Quote from: the link
Best Answer - Chosen by Asker
Every test of this theory has held true - all it would take is one single exception and the theory would need tweaking (or simply discarded and new theories based on the new observations formulated).
Based on the data alone, and the newer technologies which have, in every case, confirmed Maxwell's postulate, it is very reasonable to be confident and sure that this is, at least in part, the way the universe works.
« Last Edit: 16/03/2009 14:13:25 by Vern »
 

Offline yor_on

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Can we measure 'expansion'
« Reply #43 on: 16/03/2009 23:13:14 »
To be honest, I'm not sure what 'virtual particles' is:)
I know we have some kind of, ah, 'boiling energy' in spacetime that seems to express itself both as 'relative particles' and 'relative photons'. and we have pretty good mathematics describing them too, as well as indirect evidence for them. But a vacuum is by definition empty space?
Awh :)

I mean, you can take your trailer and drive it through any spot of 'space' and there won't be a bump!! As you seem to say DB, it may be our definitions that is dubious here. But then if I may ask, what's behind a vacuum?

 

Offline DoctorBeaver

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« Reply #44 on: 17/03/2009 00:15:53 »
But then if I may ask, what's behind a vacuum?

The person doing the housework!  :D

Seriously, though, I'm not sure what you mean by that question.
 

Offline yor_on

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« Reply #45 on: 17/03/2009 12:01:29 »
Well, if vacuum is containing such a lot of 'energy' it can't be made of 'nothing' it seems to me. Also if it is what allows for expansion then that too seems to imply that a vacuum isn't made of 'nothings'. Maybe it's a 'weak link' :) in spacetime? But then again, if that is the deal here then one have to ask what 'spacetime' is? Is it both what we can measure as being consistent in time, and those fluctuations we believe 'vacuum' to have (virtual particles/photons), inherent energy and 'expansion'.

Then the question seems to be, are they a part of what we call spacetime, or are they some kind of 'rips/exceptions' in our new model? If they are a needed part of spacetime, won't we need to 'modify' our ideas? As well as the idea of 'dimensions'? To me it all seems to hinge on the way we choose to describe spacetime, it is when we find the right way and the right words for explaining it, that the real paradigm can take place. It's always like that, it seems to me, when we don't have the 'right' words for describing a phenomena.

And that seems to me to mean that Einsteins model is a description of what is in 3D + time, but what we need is a new description of what the model should be seen as with those other parameters 'counted in'. And that takes us back to the concept of 'dimensions' and what our definitions really say about them. Perhaps they are all wrong :) Perhaps we need some new conceptual thinking of what distance is, for example. I believe in Einsteins model, as far as I understands it, but I'm not sure the 'descriptions' we use are the best, it's like we are looking at spacetime via a mirror made by preconceptions anchored in our history. LeeE seems to wonder about it for example, and I'm sure you do too DB. Another preconception of mine is that there will be a 'simple' way of describing spacetime in words, accounting for all phenomena we see, we just need to 'turn our heads'. Not that I know how, though :)

That's why I ask :)
 

Offline Vern

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« Reply #46 on: 17/03/2009 13:02:28 »
Quote from: yor_on
LeeE seems to wonder about it for example, and I'm sure you do too DB. Another preconception of mine is that there will be a 'simple' way of describing spacetime in words, accounting for all phenomena we see, we just need to 'turn our heads'. Not that I know how, though :)
There is that 'simple' way of describing nature, yor_on. John Wheeler expressed the same concerns that you express in your quote above.
Quote from: John Wheeler
Some principle uniquely right and uniquely simple must, when one knows it, be also so obvious that it is clear that the universe is built, and must be built, in such and such a way and that it could not possibly be otherwise.
I think that James Clerk Maxwell gave us that principle nearly a hundred and fifty years ago. The problem is that we have not yet accepted it. My guess, as DoctorBeaver noted before, is that we have about another hundred and fifty years to go before we accept it.
It is this: The final irreducible constituent of all physical reality is the electromagnetic field.

I knew that Maxwell had nailed it when I realized that the postulate emboldened above completely explains relativity phenomena in flat space time, and refutes any notion of Einstein-Minkowski space-time.
« Last Edit: 17/03/2009 13:07:59 by Vern »
 

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« Reply #47 on: 17/03/2009 13:50:05 »
Quote
And that seems to me to mean that Einsteins model is a description of what is in 3D + time, but what we need is a new description of what the model should be seen as with those other parameters 'counted in'.

We know that Einstein's models aren't complete even though he was a genius and a revolutionary thinker. For instance, he never tried to explain how matter warps spacetime. But even he was held back to some extent by pre-conceived beliefs. He couldn't at first accept that his calculations precluded a static universe and included the Cosmological Constant as a kludge. He did, though, finally accept the error of his ways where that was concerned.

With his ability to "think outside the box" I wonder what he'd come up with if he could come back to life now and see all the new knowledge we have acquired, all the new theories that have been devised, since his death.
« Last Edit: 17/03/2009 14:54:30 by DoctorBeaver »
 

Offline JukriS

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Can we measure 'expansion'
« Reply #48 on: 17/03/2009 14:06:13 »
Space dont expanding at all!

Energy expanding in sopace who dont expanding!

Also photons expanding and emit expanding energy and with that energy, expanding photons pushing themselfs far away same way what photons wexpanding!

thats why old light it is redshifting1

You cant see, heard, taste, smell or feel space1

You cant make any test with space!


There is no drawing force at all1

Only force is pressure!

We can explain everything with change of pressure!


All the phenomens can be explained by one force and this force is the  pressure. (Donīt forget the power of thought! You also can move yourself by the power of thought! Quite right. You get yourself to move with the help of the muscles . You so you send message of your brains to your muscles and you get yourself to move? What is power/force of this thought, which get you to move there where you want?).


We can describe by people what happens in the atomcores all the time. For example one thousand people can go to the space and curl up close to each other. Now we have made an energyconsentration of people that covers a certain spot of the space. We know that the biggest part of the atoms is empty space. Also between people there exists empty space that does not expand or curve.

Now these people can begin to straighten or in other words to open up and this way they push themselves away from each other. One can observe the hardest pressure in the middle of this human energyconsentration and people who locate in the middle must do an enormeous job so that they wounīt
flatten in the centre. These people in the centre sweat the most. This is excactly the same thing that happens without gravitation for example in the centre of the earth and in the centre of the sun.

The density of the human energyconsentration reduces and the people push themselves away from the centre of the human energyconsentration. Now for a little while we can observe a phenomen of gravitation without a drawing force (that actually does not exist) on the surface of the human energyconsentration.

In my opinion the space does not expand or curve. If it would expand, could you describe how does the space expand?

It is easy to describe how the energy all the time turns into a less dense energy in the atomcores, so I think that it is time to forget all about the magical expanding and curving of the space. You can also forget all the spare spacedimentions, the dark substance and the dark energy.

So the space does not expand or curve!

The atomcores expand and open up expanding electrons and expanding photons and they beam their expanding energy as waves away from themselves. This is how it goes!

When you look at the galaxy, you can understand that the energy inside the galaxy is denser than outside the galaxy. If you look at a star, you can understand that energy inside the star is denser than outside the star. This way you will know for sure that the energy inside the atomcore is denser than outside the atomcore. It is not difficult to understand that the energy inside the protons / neutrons is denser than outside of them and the energy inside the qvarks is denser than outside the qvarks and so on...

It it also easy to realize that outside the visible universe the is an area, where is really much more energy than the visible universe has all together and the energy some where out there is much denser than than it is in a visible universe. Still in that area far away from the visible universe there is no centre point where the energy would be denser than outside it.

That three-dimentionally expanding energyconsentration that bems energywaves with the nature of the galaxies, is formed also from separate three-dimentionally expanding energyconsentrations ect. And so the smaller separate energyconsentrations we talk about, the denser and denser the
energy is all the time.

So the atomcore does not have a centre point, where the energy would be denser than outside it. There is no centre point also at the universe, outside which the energy would be less denser.

Because the MOVEMENT takes place towards a less dense area, then the visible universe MOVES as an entity away from that one point that is really far away from the visible universe and where the energy is much denser than it is in a visible universe.

 

Offline yor_on

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« Reply #49 on: 17/03/2009 15:17:23 »
Jukris, I looked at your site, if you have a hypothesis you should place it in 'New Theories' instead of 'copy and paste' it to here. This is more or less :) 'mainstream physics' we are discussing, even though we discuss some 'weird' subjects like expansion. And none writing here is doing any polemics. It's not a 'religious subject' to us. So place your hypothesis in 'new Theories' and see what happens :)
 

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Can we measure 'expansion'
« Reply #49 on: 17/03/2009 15:17:23 »

 

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