accelerating expansion of the universe doesn't fit

[PowerEngineer]

My understanding of relativity and cosmology are admittedly superficial, however it seems to me that redshift and expansion of space are being improperly linked in this discussion.

Using relativity, the frequency shift in the light emitted by other stars is taken to be a measure of their speed towards us or away from us, and the fact that all shifts seem to be towards the red means that they're all moving away from us. This is true even if space is not expanding.

In fact, it's my understanding that any expansion of space has no effect on the redshift because the increase in distance caused by the expansion is not real movement across space (i.e. no velocity and therefore no relativistic effect). If the stars started out as stationary (i.e. pasted to the outside of the balloon) as the space expanded (i.e. the balloon inflated), the distances between them would increase but there would be no redshift.

This is why the current theories describe the "big bang" as a extremely brief period (tiny fraction of a second) of extremely rapid space expansion (towards the end of which matter percipitated out thanks to the Higgs field). The rate of expansion greatly exceeded the speed of light, but didn't violate relativity because expansion of space and movement across space are two very different things.

My two cents...

 

[bsobel]

fact, it's my understanding that any expansion of space has no effect on the redshift because the increase in distance caused by the expansion is not real movement across space

That is incorrect.

 

[silverpig]

Originally posted by: Chiropteran

Originally posted by: bsobel
The galaxies themselves aren't so much 'moving away' from us, as the space in between is growing, this is what cases the red-shift. This negates the 'maybe they appear faster because the light we see from them orginated.... when they were moving faster'

No, it doesn't negate anything. Redshift is caused by the source moving away from us. It doesn't matter if it is caused by expansion of space or by the source accelerating away from us in another. It causes the same redshift either way.

The red shifted light we see, regardless of what caused the redshift, originated billions of years ago. So my question stands.

While redshift CAN be caused by the proper motion through space of an object in relation to us, this is not the case of cosmological redshift. I'll actually go through a few reasons why this is so using two points.

1. The redshift can't be from proper motion.

-If this was true, then you'd have to say the Earth was at the center of the universe. If we say that everything is actually moving away from us through a static space, and this appears to be isotropic, then we have to be at the center of it all. If you take that we aren't at the center of the universe, then you'd see that we wouldn't see a relatively homogeneous distribution of redshifts.

2. The redshift is thus from expansion.

-Because we see the same amount of redshift in every direction, the expansion must be homogeneous. This can only come about if space itself is expanding and causing the redshift. Photons are pinned to space. If the space in which they travel expands, so does the wavelength of the photon. From looking at the redshift, you can see exactly how much the photon stretched. This tells you how much space has stretched. Comparing photons of different ages, you can tell exactly how much space has stretched between the time the oldest one was sent and the youngest one was sent because they will have both undergone the same amount of expansion since the time of the newest one's creation.

 

[Chiropteran]

Originally posted by: silverpig
1. The redshift can't be from proper motion.

-If this was true, then you'd have to say the Earth was at the center of the universe. If we say that everything is actually moving away from us through a static space, and this appears to be isotropic, then we have to be at the center of it all. If you take that we aren't at the center of the universe, then you'd see that we wouldn't see a relatively homogeneous distribution of redshifts.

2. The redshift is thus from expansion.

-Because we see the same amount of redshift in every direction, the expansion must be homogeneous. This can only come about if space itself is expanding and causing the redshift. Photons are pinned to space. If the space in which they travel expands, so does the wavelength of the photon. From looking at the redshift, you can see exactly how much the photon stretched. This tells you how much space has stretched. Comparing photons of different ages, you can tell exactly how much space has stretched between the time the oldest one was sent and the youngest one was sent because they will have both undergone the same amount of expansion since the time of the newest one's creation.

Yes. That I understand, and I do not disagree with in any way. Note the title of the thread. Accelerating expansion doesn't fit. I do not disagree that the universe is expanding, everything points to that being the case, I am just questioning whether or not that expansion is really accelerating.

The part I disagree with, is part 3 that you don't list.

3. The amount of redshift is directly proportional to the distance of the source, so sources further away are expanding away from us FASTER, which implies that the universe as a whole is expanding in an accelerating manner.

That is what I disagree with. Or rather, I can see it as a possible explanation for the data we have, but not as the only explanation. While the amount of redshift is proportional to the distance of the source, distance also equals time in this case. So my argument is that what if the distance has NOTHING to do with the speed at which the universe is expanding, and instead it's just time.


The whole theory seems really backwards to me.

Big bang- fast expansion.
Inflation- super fast expansion faster than the speed of light.
Expansion- starting out really slow and accelerating as time goes on, against gravity due to a mysterious cosmological constant.


That doesn't make much sense to me. Why would the expansion slow down and then speed back up? What is the data that supports this?

What would make more sense to me:

Big bang- fast expansions.
Inflation- super fast expansion faster than the speed of light.
Expansion- universe continues to expand carried by momentum of the big bang, gradually decelerating due to gravity.

And it would still fit the data- the further a galaxy is from us the more red shifted it would appear, because we would be seeing it's light from billions of years ago back when it was expanding faster than it is now.

 

[bsobel]

That is what I disagree with. Or rather, I can see it as a possible explanation for the data we have, but not as the only explanation. While the amount of redshift is proportional to the distance of the source, distance also equals time in this case. So my argument is that what if the distance has NOTHING to do with the speed at which the universe is expanding, and instead it's just time.

Time doesnt matter, time does not cause the red shift, its the distance traveled that does.

 

[f95toli]

Originally posted by: Chiropteran

3. The amount of redshift is directly proportional to the distance of the source, so sources further away are expanding away from us FASTER, which implies that the universe as a whole is expanding in an accelerating manner.

No, not quite. The point I think you are missing is that the speed of the source itself when the photon was released is in a sense irrelevant, it is the spacetime between us and the source that is expaning, meaning a photon emitted when the distance between us and the source was X ends up traveling a distance larger than X simply because the distance is constantly increasing. If you were to measure the redshift of the photon just after it was released it would be zero.
As bsoblel has already pointed out: Is the DISTANCE the photon has to travel that matters, not the time.

 

[Chiropteran]

Originally posted by: f95toli

No, not quite. The point I think you are missing is that the speed of the source itself when the photon was released is in a sense irrelevant, it is the spacetime between us and the source that is expaning, meaning a photon emitted when the distance between us and the source was X ends up traveling a distance larger than X simply because the distance is constantly increasing. If you were to measure the redshift of the photon just after it was released it would be zero.
As bsoblel has already pointed out: Is the DISTANCE the photon has to travel that matters, not the time.

The theory that the redshift is caused by expansion of space time is a RESULT of an interpretation of the data collected, which was showing greater redshifts in objects further away.

You can not turn around and use that as proof that the redshift is caused by space-time expansion- that is a circular argument.


Fact: redshift occurs. This can be due to velocity differences, expansion of space time, extreme gravity due to time dilation.

Theory: most of the redshift we perceive is due to space time expansion. This is a theory, not a fact.

In the early part of the twentieth century, Slipher, Hubble and others made the first measurements of the redshifts and blue shifts of galaxies beyond the Milky Way. They initially interpreted these redshifts and blue shifts as due solely to the Doppler effect, but later Hubble discovered a rough correlation between the increasing redshifts and the increasing distance of galaxies. Theorists almost immediately realized that these observations could be explained by a different mechanism for producing redshifts. Hubble's law of the correlation between redshifts and distances is required by models of cosmology derived from general relativity that have a metric expansion of space.[16] As a result, photons propagating through the expanding space are stretched, creating the cosmological redshift. This differs from the Doppler effect redshifts described above because the velocity boost (i.e. the Lorentz transformation) between the source and observer is not due to classical momentum and energy transfer, but instead the photons increase in wavelength and redshift as the space through which they are traveling expands.

This serves an explanation for why the more distant objects always seemed to be more red shifted.

However, it ignores the fact that more distant objects are also viewed as they were in the distant past.

I am offering an alternative theory: What I am suggesting is simple: what if the expansion of the universe is slowing down, instead of accelerating, how would the universe look to us? Well, if the entire universe was slowing down at about the same rate, the most distant an object is the faster it would appear to be moving away from us, because we would be looking into the past when it was still moving faster.

I want to know what the flaw is with my thinking, but you CAN NOT use something from an alternate theory to disprove this theory, it must come from observable data or accepted laws of physics. It's like saying relativity can't be true because it goes against Newtonian physics.

 

[Chiropteran]

Originally posted by: bsobel
Time doesnt matter, time does not cause the red shift, its the distance traveled that does.

The f*** time doesn't matter. Of course it matters. If something occurred 5 billion years ago that is slightly different than the same thing occurring today, don't you think?

And I never said time causes the redshift, try to keep up. I said that the red shifted light we see occurred long ago, and maybe it's only red shifted because that is what the conditions were like at the time.

 

[bsobel]

Originally posted by: Chiropteran

Originally posted by: bsobel
Time doesnt matter, time does not cause the red shift, its the distance traveled that does.

The f*** time doesn't matter. Of course it matters. If something occurred 5 billion years ago that is slightly different than the same thing occurring today, don't you think?

And I never said time causes the redshift, try to keep up. I said that the red shifted light we see occurred long ago, and maybe it's only red shifted because that is what the conditions were like at the time.

Its been pointed out numerous times now that the bolded statement is incorrect and why your having such a problem understanding this. The light wasn't redshifted at the time, the redshift occurred during its journey here.

Its clear you don't have a basic understanding of astrophysics so trying to explain this to you any more is pointless. This has been explained to you now by 3 folks that most definately understand this more than you currently do. If your not happy, go back to school. Further, comments like 'try to keep up' just show your lack of maturity.

 

[Chiropteran]

Originally posted by: bsobel

Originally posted by: Chiropteran

Originally posted by: bsobel
Time doesnt matter, time does not cause the red shift, its the distance traveled that does.

The f*** time doesn't matter. Of course it matters. If something occurred 5 billion years ago that is slightly different than the same thing occurring today, don't you think?

And I never said time causes the redshift, try to keep up. I said that the red shifted light we see occurred long ago, and maybe it's only red shifted because that is what the conditions were like at the time.

Its been pointed out numerous times now that the bolded statement is incorrect and why your having such a problem understanding this. The light wasn't redshifted at the time, the redshift occurred during its journey here.

Its clear you don't have a basic understanding of astrophysics so trying to explain this to you any more is pointless. This has been explained to you now by 3 folks that most definately understand this more than you currently do. If your not happy, go back to school. Further, comments like 'try to keep up' just show your lack of maturity.

Your "explanation" is a circular argument.

You can't use the theory in dispute to prove that it is itself correct.

My comments of "try to keep up" wouldn't be necessary if you actual read my posts instead of repeating the same things over and over. I know the existing theory, I simply disagree with it! You don't need to keep repeating what the existing theory is, it's not going to change my view. What would change my view would be if there was an independent law of physics or reason why my theory can't be right. However, you can not use a theory as evidence that it itself is true.

Theory of 1=2: 1=2

Based on my theory of 1=2, 1=2, so that proves that my theory of 1=2 is correct.

No, it does not work like that. You can not use the theory in question when you are trying to show or prove that the theory is correct.

 

[RideFree]

Originally posted by: bsobel

BUT, the light we see from galaxy "A" was actually emitted 5 billion years ago! I don't see how we can make any assumption about it's current acceleration based on how it was moving 5 billion years ago. What if it was just moving faster 5 billion years ago because it was still carrying momentum from the big bang, and has since slowed down? I don't see how we could know.

You can infer that from the relatively even distribution of mass in the universe. If it had been accelerating faster then and 'slowed' the distribution would be in bands.

bsobel,
But mass is not evenly distributed throughout the universe...to wit.
One of the latest theories to dismiss the big-bang and explain the "big hole" anomaly is the Fractal Universe model.

 

[RideFree]

Originally posted by: Chiropteran

Originally posted by: RideFree

Originally posted by: silverpig
Oh, and there's no need for your (sic) in supernovae

Zis is correct!
Superovae is one of the plural forms of supernova...
Or as they say in Spanish, estupendo no go!

Oops. I thought it was a British spelling or something, until I saw the Wikipedia entry.

It was in the dictionary long b4 Wiki...
I never feel comfortable with Wiki as the ultimate source document, although there is no denying that some of the entries are luminous...

 

[RideFree]

Every current cosmological theory is nothing more than lipstick on the pig!

My 2¢.

 

[bsobel]

my theory can't be right

Thats already been explained to you, you might want to re-read silvrpigs response (and then read it again, and then again until you understand it)

 

[silverpig]

Originally posted by: bsobel

Originally posted by: Chiropteran

Originally posted by: bsobel
Time doesnt matter, time does not cause the red shift, its the distance traveled that does.

The f*** time doesn't matter. Of course it matters. If something occurred 5 billion years ago that is slightly different than the same thing occurring today, don't you think?

And I never said time causes the redshift, try to keep up. I said that the red shifted light we see occurred long ago, and maybe it's only red shifted because that is what the conditions were like at the time.

Its been pointed out numerous times now that the bolded statement is incorrect and why your having such a problem understanding this. The light wasn't redshifted at the time, the redshift occurred during its journey here.

Its clear you don't have a basic understanding of astrophysics so trying to explain this to you any more is pointless. This has been explained to you now by 3 folks that most definately understand this more than you currently do. If your not happy, go back to school. Further, comments like 'try to keep up' just show your lack of maturity.

He does have a point though. He's asking a valid question that I'm trying to address. Lemme try again.

 

[silverpig]

Okay, so another thing you can do is look at what makes up the universe. There's an equation called the Friedmann equation which is a fairly simple relation:

A = Omega(m) + Omega(lambda) + Omega(R) + Omega(k) (there are a few forms of it).

The Omegas are the density parameters of various constituents of the universe. m is for matter (dark and regular), lambda is for vacuum energy/quintessence/cosmological constant, R is for radiation, and k is for curvature. A is some form of the Hubble parameter. What this equation gives you is the curvature of the universe (open, closed, or flat) as caused by the densities of various forms of energy (matter, radiation, vacuum).

If there's a lot of vacuum energy and not much radiation and matter, the universe is open, saddle shaped (the circumference of a circle is greater than 2*pi*r), and expands forever. If there's a lot of matter and not much else, the universe is closed, spherical (the circumference of a circle is less than 2*pi*r), and crunches.

Now, the theory of the universe is that just after the big bang, everything was governed by quantum mechanics. There were little quantum fluctuations in energy density throughout the very small universe. Then some scalar potential decayed or so I understand it, and the universe underwent inflation. At this time the quantum fluctuations were "frozen out" in the energy density of the now much larger universe. What did the fluctuations look like? Well we can see them in the cosmic microwave background anisotropy (CMB). See WMAP for that.

So there are these little density fluctuations all over the place. What does that mean for the evolution of the universe? Well, everything really. The small "seeds" would evolve and form cosmic neighbourhoods. They would do so according to some set of dynamics governed by the dominant form of energy and the curvature of space time.

WMAP made some detailed measurements of the anisotropy in the CMB and we can use computer simulations to evolve that set of initial conditions with varying numbers of the different omegas and curvature to see if they give the universe we see today.

[L]http://en.wikipedia.org/wiki/Wilkinson_Microwave_Anisotropy_Probe[/L]

Parameter Best fit (WMAP only) Best fit (WMAP + SNe + BAO)
Reduced Hubble constant h 0.719^{+0.26}_{-0.27} 0.701 ± 0.013
Baryonic content Obh2 0.02273 ± 0.00062 0.02265 ± 0.00059
Cold dark matter content Och2 0.1099 ± 0.0062 0.1143 ± 0.0034
Dark energy content, O? 0.742 ± 0.030 0.721 ± 0.015
Optical depth to reionization t 0.087 ± 0.017 0.084 ± 0.016
ns 0.963^{+0.014}_{-0.015} 0.960^{+0.014}_{-0.013}
dns / dk -0.037 ± 0.028 -0.032^{+0.021}_{-0.020}
s8 0.796 ± 0.036 0.817 ± 0.026
Age of the universe (Gigayears) 13.69 ± 0.13 13.73 ± 0.12
Total density of the universe, Otot 1.099^{+0.100}_{-0.085} 1.0052 ± 0.0064

Now they've changed the names of some of the density parameters there, broken the matter constituents into baryonic matter and cold dark matter, etc, but the thing you should look at is bolded. It's the vacuum energy which drives expansion. The same model which gets this number also shows that we just (oh a billion years ago or so I think?) crossed into the time in the universe's evolution where the dark energy becomes the dominant form of energy in the universe... leading to an explanation of the observation you see.

 

[videogames101]

Originally posted by: Chiropteran

Originally posted by: bsobel
The galaxies themselves aren't so much 'moving away' from us, as the space in between is growing, this is what cases the red-shift. This negates the 'maybe they appear faster because the light we see from them orginated.... when they were moving faster'

No, it doesn't negate anything. Redshift is caused by the source moving away from us. It doesn't matter if it is caused by expansion of space or by the source accelerating away from us in another. It causes the same redshift either way.

The red shifted light we see, regardless of what caused the redshift, originated billions of years ago. So my question stands.

From my limited knowledge...

The light from closer objects has more red-shift then light from farther objects, which proves that over time things are accelerating.

(fairly simple logic)

 

[jALLAD]

Originally posted by: Chiropteran
BUT, the light we see from galaxy "A" was actually emitted 5 billion years ago! I don't see how we can make any assumption about it's current acceleration based on how it was moving 5 billion years ago. What if it was just moving faster 5 billion years ago because it was still carrying momentum from the big bang, and has since slowed down? I don't see how we could know.

As I said above, a supernova far far away from us is *also* a supernova that occurred a long long time ago. With the information I have seen, it seems like the scientists just assume that the supernova is moving away from us faster because of the distance, while they ignore the possibility that it is moving away from us faster because it occurred a really long time ago and maybe things were moving faster back then.

what u r missing is it doesn't matter how far back in time it is. This is where special relativity comes in. since the light from say X billion yrs back reaches us, we are affected by what happened then and not what is happening now. basically what i am saying is the star might not exist at all in the present (and in all probability it probably does not, after all its been a few billion yrs since the supernova ) and we wouldn't know. so it is actually what happened then relevant to us.

and as for the acceleration, the redshift and comparison to standard candles that gives us the estimates. and they are pretty much full proof.

 

[silverpig]

Originally posted by: videogames101

Originally posted by: Chiropteran

Originally posted by: bsobel
The galaxies themselves aren't so much 'moving away' from us, as the space in between is growing, this is what cases the red-shift. This negates the 'maybe they appear faster because the light we see from them orginated.... when they were moving faster'

No, it doesn't negate anything. Redshift is caused by the source moving away from us. It doesn't matter if it is caused by expansion of space or by the source accelerating away from us in another. It causes the same redshift either way.

The red shifted light we see, regardless of what caused the redshift, originated billions of years ago. So my question stands.

From my limited knowledge...

The light from closer objects has more red-shift then light from farther objects, which proves that over time things are accelerating.

(fairly simple logic)

That's completely wrong

The farther objects have MORE redshift than closer objects.

 

[jALLAD]

@videogames101
red shifting means the frequency is lesser than what it was at the source. like a train siren, after it goes past you. so more redshift means the frequency goes lower meaning the source is traveling away from the observer faster. Look at this. http://en.wikipedia.org/wiki/Doppler_effect

 

[videogames101]

Originally posted by: jALLAD
@videogames101
red shifting means the frequency is lesser than what it was at the source. like a train siren, after it goes past you. so more redshift means the frequency goes lower meaning the source is traveling away from the observer faster. Look at this. http://en.wikipedia.org/wiki/Doppler_effect

I know? rofl

I was saying that, i assumed that things coming from farther away had less redshift, but that could be completely wrong.

 

[Chiropteran]

Let me put this another way. Ignore distance.

All the sources 1 billion years ago have x redshift
All the sources 2 billion years ago have 2x redshift
All the sources 3 billion years ago have 3x redshift
All the sources 4 billion years age have 4x redshift

Translate redshift into velocity, and the pattern is very clear:

Everything was moving away from us much faster in the past, and it is slowing down as we look at examples more recently. That shows a linear deceleration over time.



So. Based on that observed data, why do scientists claim that the opposite is actually the case, and the velocities are accelerating rather then decelerating with time? All the data indicates deceleration.

 

[silverpig]

Originally posted by: Chiropteran
Let me put this another way. Ignore distance.

All the sources 1 billion years ago have x redshift
All the sources 2 billion years ago have 2x redshift
All the sources 3 billion years ago have 3x redshift
All the sources 4 billion years age have 4x redshift

Translate redshift into velocity, and the pattern is very clear:

Everything was moving away from us much faster in the past, and it is slowing down as we look at examples more recently. That shows a linear deceleration over time.



So. Based on that observed data, why do scientists claim that the opposite is actually the case, and the velocities are accelerating rather then decelerating with time? All the data indicates deceleration.

Read my post.

Also, if you calculate velocities equivalent to those redshifts, then figure out a deceleration and strength of gravity, there isn't enough mass to slow everything down that much.

 

[RideFree]

Everything was moving away from us much faster in the past, and it is slowing down as we look at examples more recently. That shows a linear deceleration over time.

I am now thoroughly confused! (Call it mental constipation, or whatever.)

I thought that the current frenzy for proof of the existence of dark matter & energy was an effort to balance the current Cosmological model that depicts the accelerating expansion of the universe as opposed to showing a linear deceleration over time?

(Linear deceleration over time, of course, being last week's model)

 

[bsobel]

Originally posted by: RideFree

Everything was moving away from us much faster in the past, and it is slowing down as we look at examples more recently. That shows a linear deceleration over time.

I am now thoroughly confused! (Call it mental constipation, or whatever.)

I thought that the current frenzy for proof of the existence of dark matter & energy was an effort to balance the current Cosmological model that depicts the accelerating expansion of the universe as opposed to showing a linear deceleration over time?

(Linear deceleration over time, of course, being last week's model)

Your correct, your responding to the posters claim which is incorrect based on the current models. He's been asking why its incorrect.