Universe expansion

[CedrikG]

Hey folks !
Quick question.

They say that universe is expending at a faster rate. Instead of slowing down as we expected, it is actually expending faster as we look further.

As we look in space, we also look back in time. I was wondering if the fact that we see it going faster as we look further, is not simply because we look back in time, earlier after the big bang, when it was simply pushed more by the big bang at this time.

[cathouse42]

Hey folks !

Quick question.

They say that universe is expending at a faster rate. Instead of slowing down as we expected, it is actually expending faster as we look further.

As we look in space, we also look back in time. I was wondering if the fact that we see it going faster as we look further, is not simply because we look back in time, earlier after the big bang, when it was simply pushed more by the big bang at this time.

Is it exapanding?

http://dx.doi.org/10.1142/S0218271814500588

This paper says its static.

[Tiny Small]

Unfortunately, to read the journal article you have linked to, you have to be registered with the site. And yes, the general scientific consensus is that the universe is expanding. One paper stating something else does not mean we should be dropping our hats in the rush to abandon ship, and to quote a little bit of the article that we can read 'We do not claim that the consistency of the adopted model with SB data is sufficient by itself to confirm what would be a radical transformation in our understanding of the cosmos'.

If it passes peer review and all the methodology and conclusions are found to be sound, it will rewrite our understanding of the cosmos and would therefore, be massive news.

[Tiny Small]

Hey folks !

Quick question.

They say that universe is expending at a faster rate. Instead of slowing down as we expected, it is actually expending faster as we look further.

As we look in space, we also look back in time. I was wondering if the fact that we see it going faster as we look further, is not simply because we look back in time, earlier after the big bang, when it was simply pushed more by the big bang at this time.

Not quite as that would indicate a negative acceleration, or a slowing down as you move from the big bang to our present time. The way expansion is measured is through red shift. Every element in the universe emits light in one form or another and has a signature embedded into the emitted light. It shows up as absorption lines. As the origin moves and or accelerates away from us, these (unique) signatures are moved to the red end of the spectrum as the light wave is stretched out. This means that if something demonstrates redshift, it is further away from us now than it was in the past. Now, knowing that if a source of light moves away from us, it will redshift and if we know the source of light has a constant velocity, we can calculate how much it should be red shifted by, however, when we look into space almost everything we look at (Andromeda is on of the few exceptions as it's moving towards us) has a much greater redshift than it should have, meaning a positive acceleration. Repeated observations confirm a constant acceleration (meaning that the positive change in speed or direction is a constantly increasing change) and therefore, the universe really is expanding and the expansion is accelerating.

Wiki has some useful things to say about redshift; http://en.wikipedia.org/wiki/Redshift

[CedrikG]

Thanks a lot for your answer, appreciate it !
I'm so happy that you talk about Andromeda, I was going to ask a question about it soon too. I was wondering why Andromeda is coming at us ... the way I see it is like 2 car on the highway, right next each other and Andromeda is changing line into ours. In other word, its not like it was coming in our direction, at full speed on opposite direction. Am I right to see it that way ?

[ronin]

Part of the problem may be that our accelerated Universe is as said based on Red Shift.

If there is any item overlooked then the observed Red Shift may have a component additional to simple distance.

To an extent all they can say is that:

"We see a greater Red Shift then expected at extreme distances, one cause of this may be an accelerated expansion of space-time at those distances."

Sometimes I wonder if the most dramatic headline grabbing is put out first.

Concerning Andromeda, we are gravitationally bound to it, and both are heading to a common point in space. Any being in Andromeda is seeing us hurtling towards them. It really is going to make a mess of 2 fairly nice spiral galaxies when it happens.

The other galaxy in our local group is the Triangulum galaxy, I suppose that after the Milky Way and Andromeda join then that one is next on the menu. But we are part of the Virgo supercluster of something like 1500 to 2000 galaxies, many bigger then us.

[kalasinman]

I do wonder that if we see red shifted light from a star or other object 3 Bn LY away, then we are seeing 3 billion year old information. What's happening now?

If, for example the far objects had slowed or even reversed to mean universe contracting, we would not know it until the light reached us billions of years later, would we not?

[Cath]

I guess mass/matters urges "too be togevva" are stronger than the universes urge to keep us apart (locally at least)

[Cath]

I do wonder that if we see red shifted light from a star or other object 3 Bn LY away, then we are seeing 3 billion year old information. What's happening now?

Could you elaborate on your question "what happens now" ?

All we can do with such information is to modify/update our idea/model of how we as human beings are interpriting the universe as we see it.

[kalasinman]

I meant that our conclusions about the accelerating expansion of the universe is based on data that is already billions of years old by the time we get it. Red shifted then. There are valid theories that the universe is cyclic, first expanding then contracting back to unity again. Since we admittedly are ignorant of the grand processes, who's to say the far universe hasn't already started rushing towards us? The resulting blue shifted light might only arrive in 13+ billion years.

[cathouse42]

I meant that our conclusions about the accelerating expansion of the universe is based on data that is already billions of years old by the time we get it. Red shifted then. There are valid theories that the universe is cyclic, first expanding then contracting back to unity again. Since we admittedly are ignorant of the grand processes, who's to say the far universe hasn't already started rushing towards us? The resulting blue shifted light might only arrive in 13+ billion years.

We cannot determine based on one attribute alone, Redshift alone cannot determine whether it is expanding or collapsing, the paper I linked basically uses another attribute. Redshift has been shown to be erronus too. Expanding universe is one of many theories, that is all it is, a theory, I really hate it when people treat it like fact, it is anything but fact, but mearly a hypothesis, that has other hypothesis throwing it into question, like the paper I linked earlier.  using the attribute they used, it states the universe is static.

Remember some galaxies have been shown to have unusual redshifts when they are apparently phyiscall connected/interacting. The paper I linked uses the surface brightness, which should be lower on further away galaxies, however it was constant between nearby and far off galaxies, this contradicts the expanding universe thesis.

[Cath]

There are valid theories that the universe is cyclic, first expanding then contracting back to unity again. Since we admittedly are ignorant of the grand processes, who's to say the far universe hasn't already started rushing towards us? The resulting blue shifted light might only arrive in 13+ billion years.

I may be totally wrong Kalasinman, but you might be arguing with yourself .. a perfectly natural thing to do, an extremely good thing to do too !

All I could maybe add to your post, is ...

You saying "There are valid theories that the universe is cyclic" .. valid in whos eyes though ?

[kalasinman]

Arguing with myself? Well, not arguing, actually. I'm just pointing out the seeming flaw in drawing conclusions from such ancient data. To extrapolate to the extent of 13 billion years seems risky at best. I did hear Carl Sagan mention the cyclic universe concept in "Cosmos", although I believe he called it "oscillating".

[Cath]

ooohhh Carl, ever so passionate, ever so feeling

[Tiny Small]

We cannot determine based on one attribute alone, Redshift alone cannot determine whether it is expanding or collapsing, the paper I linked basically uses another attribute. Redshift has been shown to be erronus too. Expanding universe is one of many theories, that is all it is, a theory, I really hate it when people treat it like fact, it is anything but fact, but mearly a hypothesis, that has other hypothesis throwing it into question, like the paper I linked earlier.  using the attribute they used, it states the universe is static.

Remember some galaxies have been shown to have unusual redshifts when they are apparently phyiscall connected/interacting. The paper I linked uses the surface brightness, which should be lower on further away galaxies, however it was constant between nearby and far off galaxies, this contradicts the expanding universe thesis.

I think you should read up on what a theory is and how it differs from a hypothesis. Red shift is absolutely not erroneos, nor are the conclusions drawn from it. Measurement mistakes can of course be made at individual levels but the theory holds thanks to peer review. People have been unsuccesfully trying to disprove this since Edwin Hubble discovered it. Most have been shown to be either incorrect in their conclusions, or simply quacks. Just because it says something in a single paper, that doesn't make it so. Untill it has passed peer review, it is a hypothesis only so please don't tout it as fact. Expansion is an increadibly well tested theory and is as close to a fact as you can get. By the way, gravity is 'only a theory', but I don't see you floating away into space.

Don't get me wrong, it may be disproven at somepoint, but I doubt it will be by this paper.

[Tiny Small]

Arguing with myself? Well, not arguing, actually. I'm just pointing out the seeming flaw in drawing conclusions from such ancient data. To extrapolate to the extent of 13 billion years seems risky at best. I did hear Carl Sagan mention the cyclic universe concept in "Cosmos", although I believe he called it "oscillating".

Accellerating expansion goes a long way to disprove that. Current thinking (though as far as I am aware this is still at the stage of being a hypothesis) is that the big bang was actually a small bang that is part of an ongoing, fractal big bang which ties very neatly into the multiverse theory.

An important point is raised by an accellerating expansion though, and that is, no matter how long we look for, the edge of the observable universe will only ever appear to get closer, not further away, right upto the point where any galaxy will be visibly alone in the cosmos. There will come a time when inhabitants of a galaxy will look into their night sky and see only the cooling remnants of the nearby stars of their own galaxy and nothing else. It makes me very glad to be alive right now.

[cathouse42]

I think you should read up on what a theory is and how it differs from a hypothesis. Red shift is absolutely not erroneos, nor are the conclusions drawn from it. Measurement mistakes can of course be made at individual levels but the theory holds thanks to peer review. People have been unsuccesfully trying to disprove this since Edwin Hubble discovered it. Most have been shown to be either incorrect in their conclusions, or simply quacks. Just because it says something in a single paper, that doesn't make it so. Untill it has passed peer review, it is a hypothesis only so please don't tout it as fact. Expansion is an increadibly well tested theory and is as close to a fact as you can get. By the way, gravity is 'only a theory', but I don't see you floating away into space.

Don't get me wrong, it may be disproven at somepoint, but I doubt it will be by this paper.

1) The first paper I linked IS peer reviewed.

Here is another paper http://arxiv.org/ftp/astro-ph/papers/0509/0509611.pdf on this topic.

[Tiny Small]

1) The first paper I linked IS peer reviewed.

Here is another paper http://arxiv.org/ftp/astro-ph/papers/0509/0509611.pdf on this topic.

Just going to read it now, though on a quick skim read, they are basing some of their assumptions on 'some other unknown factors'... But let me read it first. 

The traditional big bang model first hypothesised by Hubble has already been shown to be largely incomplete, however, the theories of expansion when combined with the big bang suggest a fractal universe which the CMB supports to a very large extent.

Also remember, just because it has been peer reviewed, doesn't mean that it has been accepted as accurate As they implied in the introduction to the first paper you linked to, if it turned out to be true, it would rewrite our knowledge of the cosmos. Unfortunately, relativity substantially backs up many of the claims of expansion and relativity itsself has passed every test it has been given so far.

[Tiny Small]

Just out of interest, a couple of questions:

Do you personally believe in an infinite universe?

Did you Google the author of both of these papers you have linked to?

Eric Lerner is a known contrarian who buys into theories that violate the laws of thermodynamics and his work has largely been dismissed by the scientific community. He is a focused plasma researcher (nothing to do with cosmology) and doesn't, from what I can find out, hold a PhD. Going down the PROMPT checklist, this paper and the author fail many of the requirements to gauge reliability. I would put very little faith in this paper I'm sorry to say.

[Tiny Small]

Okay... I got a few pages into it before I couldn't take it anymore. I'm sorry but that paper is utter nonsense. Firstly, it is terribly written and referenced. The language does not clearly communicate what the author wishes to state (riddled with spelling and gramatical errors), the author does not make clear his position of interest or his field of research, there are clearly vested interests as this chain of thinking allies itsself to his actual field of research and could potentially gain him funding for that field. His methodology is vague at best and certainly not clearly presented. The source of publication is not varified and his only contact details on the undated paper are an email address. The paper was written with the support of a commercial company that he is the president of and he is refferencing extremely old data.

Then, when you start reading the paper, it falls apart instantly. His entire argument is based on this corker of a line; 'In contrast, if the universe is not expanding, and the redshift-distance relationship is due to some other phenomena, surface brightness is independent of distance and thus of redshift'. I'm sorry, but which phenomena would that be? He constantly makes propositions based on information from his colleagues and then dismisses the heavily substantiated views of mainstream science, to make his argument stronger but without providing a viable alternative for the explanations given. In fact, not only does he not provide a viable alternative to mainstream views, he provides no alternative. He also cherry picks his data whilst admitting in his own paper that this data is very limited in its scope and relevence.

If you are going to reject a dataset in order to validate your hypothesis whilst admitting that the results of that dataset are in fact real, you can't just dismiss it without explanation. You have to provide an alternative hypothesis to explain the results and incorparate that into your wider hypothesis.

I would put zero faith in this paper. I'm sorry, but you need to apply better critical think to your information sources.

[Tiny Small]

 I was wondering why Andromeda is coming at us ... the way I see it is like 2 car on the highway, right next each other and Andromeda is changing line into ours. In other word, its not like it was coming in our direction, at full speed on opposite direction. Am I right to see it that way ?

Yes is the short answer to that

[kalasinman]

Really? I guess I was wrong to assume that as they are moving towards each other due to gravity, that the larger mass of M31 would mean that MW would do more of the course changing.

[Tiny Small]

You are not wrong at all. He was asking if they were heading directly towards each other. Which they're not. To use the OP's analogy, it's like two cars heading the same way then merging into the same lane (though at a somewhat more aggressive angle). Though Andromeda has hugely more mass than the MW so we will be gravitationally affected to a greater degree.

[kalasinman]

"Andromeda is changing line into ours." was the part I was responding to. The idea that M31 is doing the moving.

My understanding is that nothing in the universe travels in a linear manner. All moving in various curving paths. Therefor MW and M31 are each moving into each others paths, although at different rates of angular change.

[Tiny Small]

Yup. Though the OP's analogy serves the purpose of demonstrating it wont be a head on collision... not that that really matters with galaxies I suppose. Shame I'm not going to be around to witness that. Pretty annoyed about it to be honest.