Is the Universe Expanding?

[SpeedFreek]

My post describing a model of expansion is simply a model analogy, an extension of the balloon model. My "definition" of the observable universe, and the post about the observed redshift relationships, are a laymans guide to the mainstream view in cosmology, the Lambda-CDM concordance model.

I was not attempting to offer proof, I was simply explaining what the mainstream theory actually means, as a lot of people argue against it without even understanding it.

It is the standard model in cosmology, you just haven't heard it described quite like that before.

 

[MeteorWayne]

SpeedFeek,
I think it was a superb effort. I'm going to keep it in my archives to help laymen understand the concepts. Thanx!

Those that don't even read their own links would have a hard time arguing with it

 

[xXTheOneRavenXx]

Wow, of all the description I have read to the expansion, that is the best one I have seen yet. Well done Speedfreak

 

[SpeedFreek]

Here is a little list of the different distance measures used in the current mainstream model of the expanding universe.

Light-travel time.

z=0.1___a galaxy whose light is 1.2 billion years old.
z=0.5___a galaxy whose light is 5 billion years old.
z=1____a galaxy whose light is 7.7 billion years old.
z=1.4___a galaxy whose light is 9.1 billion years old.
z=7_____a galaxy whose light is 12.9 billion years old
z=1089___the CMBR, which is 13.7 billion years old.


Angular diameter distance.

z=0.1___a galaxy that was 1.2 billion light-years away
z=0.5___a galaxy that was 4 billion light years away
z=1____a galaxy that was 5.4 billion light years away
z=1.4___a galaxy that was 5.7 billion light-years away
z=7_____a galaxy that was 3.5 billion light-years away
z=1089___a CMBR photon that was emitted 42 million light-years away.


Comoving distance.

z=0.1___a coordinate that has receded to 1.35 billion light-years away.
z=0.5___a coordinate that has receded to 6.1 billion light-years away.
z=1____a coordinate that has receded to 10.8 billion light-years away.
z=1.4___a coordinate that has receded to 13.8 billion light-years away.
z=7_____a coordinate that has receded to 29 billion light-years away.
z=1089___a coordinate that has receded to 46.5 billion light-years away.

 

[Fallingstar1971]

Is space expanding? If it is, what is it expanding in too?

If it is, is the rate of expansion the same everywhere?

If its not, then what mechanism/process is either restricting or enhancing expansion at any given point? Why are things far away moving faster than things closer to us?

But even more amazing than that.........

If space is expanding, then what about the space between our atoms? What is the force stopping them from expanding.
Could this imply that space can be broken down into an observable lower limit? Could one atomic radius represent the smallest measurable unit of space, since it doesnt expand?

or does it

If space everywhere were expanding at the same rate you would never be able to measure it.

Your measuring tools, the distances between graduations on your ruler, everything would expand at the same rate, at the same proportion, the ruler would get bigger, the distances between say one cm and two cm would increase, but you wouldn't even be able to see it because every measuring tool in existence has expanded at the same rate making one cm bigger than it was prior to expansion.

So I guess it boils down to this

If space is truly expanding, then what is the force that is regulating expansion so that different areas of space expand at different rates? In other words, what is the force that is staggering expansion just enough so that we can observe it?

 

[SpeedFreek]

Hi there fallingstar. Have a look at the PDF file below, it will give you some insight into these concepts.

Misconceptions about the Big Bang

 

[Mee_n_Mac]

Great set of posts SF !!! It's stuff like this that makes SDC special.

 

[brellis]

I'm glad I poked my head in here -- once again I need some cosmological reassurance from speedfreek. <--there's a delicious irony gaining intellectual calmness from a dude named speedfreek

I just read Bob Berman's article "Edges of the Universe" in the August 2009 Astronomy Mag, and once again, I'm lost! He quotes Ned Wright of UCLA as saying that the light from 98.4% of the universe will never reach us, and that some sort of Great Attractor accelerates the expansion of the universe, and lies in the direction of Centaurus.

I still have my head around the fact that the "direction" of the Big Bang is everywhere; we're part of the big Bang. All good.

Do we have a location on a universal balloon-type of map? If so, can't we suggest a "direction" of the Big Bang in relation to some of the more distant objects we've spotted? I'm gonna look through the Lineweaver-Davis pdf -- thanks for that, speedy!

 

[SpeedFreek]

Hi there brellis!

I don't have a subscription, so I cannot see the article, but I suspect Berman is referring to the "dark flow".

 

[chris1996]

Yes, and because of dark energy it is speeding faster and faster and faster.
In the far distant future the Universe is expected to be expanding at almost lightspeed. :!:

 

[ramparts]

I find this topic interesting It would be considered the biggest waste of time in the world if scientists were to discuss the question "is the universe expanding?" because it's so obviously true. But on SDC, all of us budding Einsteins may come to whatever conclusions we please, and indeed be very adamant about them

 

[xXTheOneRavenXx]

Good day all,

First I must apologize for my lengthly absence. This years flu bug really hit my family (including myself) hard. I was down with it for about a week. Before that my children and wife had it. Then some sort of bacteria attacked my immune system while I was already combating the flu. Had some throat swelling issues because of it, and just got back on my feet now after all the antibiotics so graciously supplied to me from the doc Now I'm back, and ready once again to get into some really deep discussions that i love so much here at SDC

I'm glad I poked my head in here -- once again I need some cosmological reassurance from speedfreek. <--there's a delicious irony gaining intellectual calmness from a dude named speedfreek

I just read Bob Berman's article "Edges of the Universe" in the August 2009 Astronomy Mag, and once again, I'm lost! He quotes Ned Wright of UCLA as saying that the light from 98.4% of the universe will never reach us, and that some sort of Great Attractor accelerates the expansion of the universe, and lies in the direction of Centaurus.

I still have my head around the fact that the "direction" of the Big Bang is everywhere; we're part of the big Bang. All good.

Do we have a location on a universal balloon-type of map? If so, can't we suggest a "direction" of the Big Bang in relation to some of the more distant objects we've spotted? I'm gonna look through the Lineweaver-Davis pdf -- thanks for that, speedy!

I have read about Dark Flow myself, and it baffled me as well that some sort of "Great Attractor" could be accelerating the expansion of the universe. To me, to assume a specific object or a single entity isolated to a specific location could be the cause of the entire expansion would lead me to also assume this "thing" exists either outside the universe, or at least encompases it. Is it that in the direction of Centaurus is supposed to be found the source of the expansion? But isn't dark energy that is spread throughout the universe the cause? or is there such a large gravitational force (for whatever reason) in that direction of space that it could be attracting enormous amounts of mass? The whole dark flow and the "direction" it moves in is also something I cannot get my mind around either. Can anyone shed some light on this issue? I know it's a whole other topic in itself, but it certainly does cross paths with the expanding universe in ones understanding of it in comparison to the Dark Flow.

 

[SpeedFreek]

As I understand it, the "dark flow" does not apply to the whole observable universe, but only to a certain part of it, which seems to be attracted in a certain direction as if there is something unseen causing a large gravitational influence in that direction. It is not related to dark energy as far as I know, and there are currently arguments as to whether the "dark flow" is a physical phenomena or a statistical error.

 

[harrycostas]

G'day

I have been away so to speak and yet I find the same type of dicussion.

Very little mention of the various mechanisms in creating redshift particularly the intrinsic properties of outgoing accelerated matter from supernova influencing the redshift data.

Particularly this paper that I have posted before.

http://arxiv.org/abs/astro-ph/0405083

Another origin of cosmological redshifts

Authors: Michael A. Ivanov
(Submitted on 5 May 2004)

Abstract: If gravitons are super-strong interacting particles which fulfill a flat non-expanding universe, we would have another possibility to explain cosmological redshifts - in a frame of non-kinematic model. It is shown by the author that in this case SNe 1a data may be understood without any dark energy and dark matter. A value of relaxation factor is found in this paper. In this approach, we have Newton's law of gravity as a simplest consequence, and the connection between Newton's and Hubble's constants. A value of the latter may be theoretically predicted.

 

[SpaceTas]

Answering thread question. Yes Virginia the Universe (all space-time, matter in energy) is expanding.
Evidence 100's of thousands of galaxy radial velocity measurements, along with a sub sample of galaxy distance measurements using a variety of methods.

 

[R1]

Actually gravity and and all attractive forces are contracting, are they not?
(There is also no complete certainty that gravity will forever be as effective, either, I think.)

 

[harrycostas]

G'day

It's just amazing how people can just say the universe is expanding and yet the actual distances are not. But! the maths theory states that space/time is doing the expanding.

I have been looking at the evidence and still I cannot find one evidence that can show me that the universe is expanding. I say this and I have many stating that the universe is expanding.

If someone can prove it without ad hoc theories, I'm all ears.

 

[origin]

G'day

It's just amazing how people can just say the universe is expanding and yet the actual distances are not. But! the maths theory states that space/time is doing the expanding.

I have been looking at the evidence and still I cannot find one evidence that can show me that the universe is expanding. I say this and I have many stating that the universe is expanding.

If someone can prove it without ad hoc theories, I'm all ears.

Huh? Who says the distances are not getting greater? No reputable scientist is saying this.

There is ample evidence that has been presented here and can be found all over the internet - even wiki is pretty good on this one. What kind of proof are you looking for?

The theories are based on the evidence of the expanding universe. For you to say you have not seen any evidence can only mean that you have not looked or you must have some sort of preconcieved opinion - which no amount of evidence will change.

 

[SpeedFreek]

It's just amazing how people can just say the universe is expanding and yet the actual distances are not. But! the maths theory states that space/time is doing the expanding.

Actual distances are increasing, at cosmological scales.

I have been looking at the evidence and still I cannot find one evidence that can show me that the universe is expanding. I say this and I have many stating that the universe is expanding.

If someone can prove it without ad hoc theories, I'm all ears.

What sort of proof do you require? What do you consider to be ad hoc?

It seems as if the expansion of the universe cannot be experimentally proven in a laboratory, at present. It has no measurable effect within galaxies, or clusters of galaxies. It only has an effect over the immense distances between the clusters of galaxies.

All we can do is look out into the universe and see if we can work out what is going on, at a distance. Due the finite speed of light, the longer the light takes to reach us, the further back in the history of the universe we see.

What do we see? How can we explain what we see?

http://www.talkorigins.org/faqs/astronomy/bigbang.html

 

[csmyth3025]

There was a recent article at Space.com on "Dark Flow". From the article I gather that there is a group of astronomers who have compiled evidence that there are a significant number of superclusters of galaxies moving in a particular direction. They also can't find a reason why these superclusters should be doing this.

I understand that these observations are controversial and that there is some doubt in the astronomical community about whether they (the observations) and the analysis of the raw data are correct.

I'm sure that, in time, other researchers will either substantiate these observations or show that the data has been misinterpreted. On the general question of whether such an effect is plausible, though, I wonder why such unexplained movement would be considered an outlandish claim. In recent years we've come to the conclusion that our Universe is composed of about 74% "dark energy" (which we can't detect except by its apparent large-scale "anti-gravity" effect), about 22% "dark matter" (which we can't detect except by its apparent mid-scale gravity effect), and about 4% of stuff we can see and measure.

It seems the Universe still has a lot of secrets yet to be discovered. In spite of the "Standard Model", which tends to give a lot of civilians like me a warm and fuzzy feeling that Science has it all figured out, I think there is still a lot of new and surprising science ahead of us. That's why I like it so much.

Chris

 

[origin]

There was a recent article at Space.com on "Dark Flow". From the article I gather that there is a group of astronomers who have compiled evidence that there are a significant number of superclusters of galaxies moving in a particular direction. They also can't find a reason why these superclusters should be doing this.

I understand the these observations are controverial and that there is some doubt in the astronomical community about whether they (the observations) and the analysis of the raw data are correct.

I'm sure that, in time, other researchers will either substantiate these observations or show that the data has been misinterpreted. On the general question of whether such an effect is plausible, though, I wonder why such unexplained movement would be considered an outlandish claim.

In general one would expect super clusters to be moving away from each other due to the expansion of the universe. If they are not then this is a pretty surprising phenomina, hence the controversy.
It is plausible I suppose if there is VERY big gravity well pulling them in one direction.

In recent years we've come to the conclusion that our Universe is composed of about 74% "dark energy" (which we can't detect except by its apparent large-scale "anti-gravity" effect), about 22% "dark matter" (which we can't detect except by its apparent mid-scale gravity effect), and about 4% of stuff we can see and measure.

One point here - 'dark energy' is not anti-gravity. Anti-gravity would cause masses to repel each other. That is not what dark energy 'does', dark energy is responsible for the accelerating expansion of the universe.

It seems the Universe still has a lot of secrets yet to be discovered. In spite of the "Standard Model", which tends to give a lot of civilians like me a warm and fuzzy feeling that Science has it all figured out, I think there is still a lot of new and surprising science ahead of us. That's why I like it so much.
Chris

Science certainly does not have it all figured out, which any scientist would tell you. We know a heck of a lot about the universe, but there are a great many things we don't know. Heck there are things we don't know that we don't know, to paraphrase Rummy.

 

[Fallingstar1971]

How about a 5 dimensional hypercube rotating on two axis(s)? with our "Universe" being but one face of the cube. As it spins, it creates the illusion of expanding and contracting as each face is rotated away and twords the center of the cube.

Perhaps the Universe occupies more than one side on said cube. Now we can have our dark flow and it would be expected, and not such a surprise. Expansion is expected as well.

So what I am saying, is that it just may be possible to have a finite universe, verses an infinite one. Granted, nobody really has documented any contraction......just expansion.

Just a thought

Star

 

[csmyth3025]

I apologize for my rather simplistic analogy that dark energy is a sort of "anti-gravity" on large scales. It seemed at the time to be a conveniently compact way of describing the effect.

Newton originally described gravity as an attractive force between massive particles (or bodies) in 1687. It's my understanding that he wasn't happy with the idea of "spooky action at a distance" (a phrase that Einstein would later coin in 1935 to describe his displeasure with the notion of quantum entanglement). Einstein, of course, later showed that matter (or, equivalently, energy) distorts space and time - with the result that there seems to be an attractive force between massive particles (or bodies).

On large scales dark energy seems to be causing space to expand at an accelerating rate. It's unclear to me whether this effect is best described as a true expansion of space or whether it, too, may be a distortion of space-time.

Chris

 

[origin]

On large scales dark energy seems to be causing space to expand at an accelerating rate. It's unclear to me whether this effect is best described as a true expansion of space or whether it, too, may be a distortion of space-time.

The measurments of the recession of distance objects corelates to a true expansion.

 

[ramparts]

I apologize for my rather simplistic analogy that dark energy is a sort of "anti-gravity" on large scales. It seemed at the time to be a conveniently compact way of describing the effect.

Newton originally described gravity as an attractive force between massive particles (or bodies) in 1687. It's my understanding that he wasn't happy with the idea of "spooky action at a distance" (a phrase that Einstein would later coin in 1935 to describe his displeasure with the notion of quantum entanglement). Einstein, of course, later showed that matter (or, equivalently, energy) distorts space and time - with the result that there seems to be an attractive force between massive particles (or bodies).

On large scales dark energy seems to be causing space to expand at an accelerating rate. It's unclear to me whether this effect is best described as a true expansion of space or whether it, too, may be a distortion of space-time.

Chris

Chris, this is actually a wonderful (and very accurate) description. And I think referring to dark energy as having anti-gravitational effects is fine, at least colloquially. Yes, it uses a gravitational interaction but it does so repulsively, which is contrary to pretty much everything we think of as gravity.