Is the Observable Universe getting smaller?

[Prof.Layman]

Prof Layman, you need to read Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe by Davis and Lineweaver. This should get you interested:

"We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light."

I have to say that this paper has more references to contradictions of what is said in it than I have ever seen. I think I like this one, “it is neither useful nor strictly correct to interpret the frequency shifts of light
from very distant sources in terms of a special-relativistic D¨oppler shift alone." As the whole paper seems to do this...

I don't think any of the concepts in this paper has really gone mainstream yet, as written in books for the general public. They all tend to agree that galaxies close to the edge of the visable universe are traveling close to the speed of light, and are even quoted in that paper as saying so. I think this one probably explains it best from the paper, also considering that scientist have recently confirmed that the universe is exanding exponentially and the speed is increasing.

Harrison, E. R. 1991, ApJ, 383, 60–65, Hubble spheres and particle horizons, All accelerating universes, including universes having only a limited period of acceleration, have the property that galaxies at distances L < LH are later at L > LH, and their subluminal recession in the course of time becomes superluminal. Light emitted outside the Hubble sphere and traveling through space toward the observer recedes and can never enter the Hubble sphere and approach the observer. Clearly,
there are events that can never be observed, and such universes have event horizons.” The misleading part of this quote is subtle – there will be an event horizon in such universes (accelerating universes), but it needn’t coincide with the Hubble sphere. Unless the universe is accelerating so quickly that the Hubble sphere does not expand (exponential expansion) we will still observe things from beyond the Hubble sphere, even though there is an event horizon.

 

[Farsight]

I'm not sure myself Prof, but Perlmutter et al's discovery dates from 1998, see this. The Davis & Lineweaver paper is peer reviewed, and dates from 2003. It's referred to on the wikipedia Metric expansion of space page. It's even the first reference, and they usually play a fairly safe bat on wiki. Anyway, see this from the conclusion:

"We showed that the Hubble sphere is not a horizon - we routinely observe galaxies that have, and always have had, superluminal recession velocities. All galaxies at redshifts greater than z ∼ 1.46 today are receding superluminally in the ΛCDM concordance model."

There's far higher redshifts than that, see wikipedia. One of them is UDFy-38146639 with a redshift of 8.6. And we can see it.

 

[Prof.Layman]

I'm not sure myself Prof, but Perlmutter et al's discovery dates from 1998, see this. The Davis & Lineweaver paper is peer reviewed, and dates from 2003. It's referred to on the wikipedia Metric expansion of space page. It's even the first reference, and they usually play a fairly safe bat on wiki. Anyway, see this from the conclusion:

"We showed that the Hubble sphere is not a horizon - we routinely observe galaxies that have, and always have had, superluminal recession velocities. All galaxies at redshifts greater than z ∼ 1.46 today are receding superluminally in the ΛCDM concordance model."

There's far higher redshifts than that, see wikipedia. One of them is UDFy-38146639 with a redshift of 8.6. And we can see it.

I think they should have given him the nobel prize for this discovery. It is news to me, not much literature on the shelf really reflects this type of claim. Not that any more books has been written here lately than there was before that mostly assumed there was a FTL horizon of the universe, and I don't know of any that claim otherwise. It would change a lot of popular theories if there was proved to be no FTL horizon. I would have to think that we can only see galaxies traveling less than c and the claim by so many sources would have had to been backed up by some kind of data. I don't think they could all possibly make this same outlandish claim.

 

[Farsight]

Maybe an analogy might help here.

Imagine you've got an elastic rope 2m long. A caterpillar at the far end of the rope crawls towards you at 1m per minute.
After 1 minute the caterpillar is only 1m away from you, and is midway along the rope.
You now stretch the rope to 3m. The caterpillar doesn't have to cover an extra 1m, because the rope behind it stretched. It now has to cover 1.5m to reach you.
After another minute the caterpillar is only 0.5 metres away from you.
You now stretch the rope to 4m. The caterpillar doesn't have to cover an extra 1m, because the rope behind it has stretched. It now has to cover 0.66m to reach you.
After another minute the caterpillar is in yer face.

You could slice up this scenario by using centimetres and seconds, and you can even stretch the rope first. Let's start with a 100cm rope:

After 0 seconds the caterpillar is 100.00cm away from you and you stretch the rope 1cm. The caterpillar is now 100.0 x 101/100 = 101.00cm away from you.
After 1 seconds the caterpillar is 100.00cm away from you and you stretch the rope 1cm. The caterpillar is now 100.0 x 102/101 = 100.99cm away from you.
After 2 seconds the caterpillar is s99.99cm away from you and you stretch the rope 1cm. The caterpillar is now 99.99 x 103/102 = 100.97cm away from you.
After 3 seconds the caterpillar is s99.97cm away from you and you stretch the rope 1cm. The caterpillar is now 99.97 x 104/103 = 100.94cm away from you.
After 4 seconds the caterpillar is s99.94cm away from you and you stretch the rope 1cm. The caterpillar is now 99.94 x 105/104 = 100.90cm away from you.
After 5 seconds the caterpillar is s99.90cm away from you and you stretch the rope 1cm. The caterpillar is now 99.90 x 106/105 = 100.85cm away from you.
After 6 seconds the caterpillar is s99.85cm away from you and you stretch the rope 1cm. The caterpillar is now 99.85 x 107/106 = 100.79cm away from you.

Anyway, you get the picture. Somebody check my arithmetic, but even though the far end of the rope is receding from you at 1cm per second and the caterpillar is crawling towards you at 1cm per second, the distance between it and you is reducing faster and faster. It keeps on chugging towards you, and it will eventually reach you.

 

[Prof.Layman]

I don't have a problem seeing how galaxies can overcome the speed of light barrier, I just don't see how the paper proves that the speed of the furthest visable galaxies are traveling greater than the speed of light as we see them in the state they are in. It is like asking the question what happens to the ships headlights when it is traveling close to the speed of light. The passengers in the ship observe the headlights to behave normally, no matter what constant speed they are traveling. This is like saying that if the ship went faster than the speed light, we could observe its headlights as they would be seen normally, over long distances. The paper itself says all the books are wrong, and they would all have to be if that paper was right. Other theories like the expansion of space itself causing the doppler shift and theories on space moving that prevents light from reaching us from within a black hole may not even be able to account for this interpretation of how far and how fast the furtherst galaxies are traveling.

 

[Farsight]

I don't have a problem seeing how galaxies can overcome the speed of light barrier, I just don't see how the paper proves that the speed of the furthest visable galaxies are traveling greater than the speed of light as we see them in the state they are in.

My caterpillar example demonstrates that you can see a galaxy receding from you at the speed of light. That's the main thing to understand. And get this: once the caterpillar is less than 50cm away from you, you could start stretching a 100cm rope at 2cm per second, and the caterpillar still makes it.

It is like asking the question what happens to the ships headlights when it is traveling close to the speed of light. The passengers in the ship observe the headlights to behave normally, no matter what constant speed they are traveling.

It's different to that Prof. The caterpillar makes it because it's space stretching. If he started out genuinely moving at 1cm/s away from you and then set off towards you at 1cm/s, he goes nowhere.

This is like saying that if the ship went faster than the speed light, we could observe its headlights as they would be seen normally, over long distances.

I don't think it is. This space stretching thing isn't the same as SR relative motion.

The paper itself says all the books are wrong, and they would all have to be if that paper was right.

The books are always wrong in some respect. If they weren't, we wouldn't have scientific progress and new books.

Other theories like the expansion of space itself causing the doppler shift..

The expansion of the universe and cosmological redshift seems well-supported even though it's not a totally complete theory.

theories on space moving that prevents light from reaching us from within a black hole...

Space moving? Space doesn't move near a black hole. If you're referring to the "waterfall" analogy for a black hole, be cautious. IMHO it ends up with people saying gravity is all to do with the sky falling in.

may not even be able to account for this interpretation of how far and how fast the furtherst galaxies are traveling.

There's always room for improvement, but general relativity is a well-tested theory, see The Confrontation between General Relativity and Experiment by Clifford M Will. My reading of all this is that some cosmologists haven't quite understood GR properly.

 

[Prof.Layman]

The books are always wrong in some respect. If they weren't, we wouldn't have scientific progress and new books.

Science doesn't really change that much over time. I don't know of any scientific fact that was textbook and then had to be taken back because it was in error. I think it is way more likely that the paper is in error, like some other papers I have seen on the internet. It is hard to imagine how the speed of the most distance galaxies we can see have been misinterpretted for decades. I would have to think that the manner the paper determines this is just wrong or doesn't agree with how many other scientist calculated the speed of distance galaxies. If no one can recreate the results of the paper, it is just not science.

 

[Farsight]

It's a bona-fide paper, Prof, and my caterpillar example makes it clear that the salient point it makes is correct. If you can demonstrate that I'm somehow mistaken all well and good, but otherwise please don't dismiss it.

Why has this thread been moved to pseudoscience? And by whom?

 

[Prof.Layman]

It's a bona-fide paper, Prof, and my caterpillar example makes it clear that the salient point it makes is correct. If you can demonstrate that I'm somehow mistaken all well and good, but otherwise please don't dismiss it.

Why has this thread been moved to pseudoscience? And by whom?

IDK, I would like to have a secound opinion on the speed of distant galaxies, or maybe cosmology has gotten so bad that this question is beyond our current understanding of science. I actually only read from one source on the speed of distance galaxies I don't recall what book that was called, most other types of laymans text don't really mention it. I think that is why it stood out in my mind as being the only mention of it really.

I think the leading theory is Alex Philipinco (sp?), from the University of California theory that space actually moves near a black hole, was also in charge of the other team that won the 2011 Nobel Prize that discovered that the cosmological constant is increasing. He still claims that space itself over this long distances is still relatively flat. I don't think this theory could ever apply to the the expansion of the universe (that space actually moves) if objects traveling FTL with the expansion of space are still visable. I never heard of a caterpillar type of description of space, is this one of your own theories?

I think you are allowed to post your own personnel ideas on pseudoscience, and most orginal ideas in science are seen as such no matter how valid they may be. Nothing to lose now, the ship has been sunk. I don't think the topic question has been answered currently in science as of date. How could it, we just discovered that the speed of those galaxies is increasing? To as far as how fast they where moving, no one may still never know for sure, they completly failed at giving out that type of information. But, I think the size of the observable universe changing over time is a new idea.

Maybe I could ask the Universe, and he will answer it on the show.

 

[hardalee]

If something is moving away from the observer at over the speed of light, the light will never reach the observer. Period. All else is woo woo.

I mean that as always in the nicest possible way.

 

[Prof.Layman]

If something is moving away from the observer at over the speed of light, the light will never reach the observer. Period. All else is woo woo.

I mean that as always in the nicest possible way.

How could you be so certain if the speed of the photon is not affected by the velocity of the object that is emmitting it?

 

[hardalee]

SR.Woo Woo. Good night.

 

[Farsight]

How could you be so certain if the speed of the photon is not affected by the velocity of the object that is emmitting it?

Because it has a wave nature rather than a "billiard ball" nature. The speed of the emitter doesn't matter.

The caterpillar is only my analogy, intended to help explain the salient point of the Davis/Lineweaver paper. Why don't you ask around elsewhere about that paper? Copy and paste the caterpillar analogy and ask if it's a reasonable albeit simplified explanation of why "...we can observe galaxies that have, and always have had, recession velocities greater than the speed of light."

 

[Quantum Quack]

I was thinking about some descriptions or explanations popularized by physicist on television that explain why light cannot escape a black hole and some concepts involving the observable universe, and I came to a conclusion that the observable universe must be seen to be getting smaller.

For starters, it has been said that the reason why light cannot escape a black hole is because the space itself around a black hole is traveling faster than the speed of light. So then the edge of the visable universe has galaxies that are traveling close to the speed of light. Then they do this because the space itself is expanding away from us close to the speed of light, and it has been said that this is okay because it is the space itself that is traveling faster than light. So then I assume that the reason why we cannot see galaxies past the edge of the visable universe is because the space itself is expanding away from us faster than the speed of light. So then what happens when these galaxies traveling away from us close to the speed of light end up traveling away from us faster than the speed of light with the expansion of space? They would no longer be able to be seen in our visable universe. Then since the rate of expansion is increasing, then the distance away from us where galaxies are traveling faster than the speed of light will become closer and closer to us. So then it seems like it would follow natuarally that the observable universe is getting smaller since the distance a galaxy would travel faster than the speed of light would become increasingly closer to us over time.

It seems like a strange concept, but over the past few decades the age of the universe hasn't seemed to get any older. Could this cause our preception of the age of the universe to always appear to be getting younger?

You refer to all this inofrmation as if it is relevant to today? why?
How is historical doppler shift information relevant to today?
How many light years ago are we talking about?
Is the observable universe getting smaller....hmmmm maybe it was maybe it wasn't who knows what is happening today? any one?

It seems we keep forgetting that rule of light info delays and how that effects our understanding of the universe...today...

 

[Prof.Layman]

You refer to all this inofrmation as if it is relevant to today? why?
How is historical doppler shift information relevant to today?
How many light years ago are we talking about?
Is the observable universe getting smaller....hmmmm maybe it was maybe it wasn't who knows what is happening today? any one?

It seems we keep forgetting that rule of light info delays and how that effects our understanding of the universe...today...

The view that space is actually expanding or getting bigger is still used to explain the doppler shift from distant galaxies. If we could even be certain that there even is a FTL horizon, and that horizon already has galaxies that are traveling close to the speed of light, then the universe could be much older than we think it is. We would also calculate the universe to always to get younger over time, like we have done. If space is actually moving than I think there could still be a FTL horizon with the expansion of space, even though the photon is unaffected by this relative velocity. It is hard to know the distance of these galaxies mainly because it seems like no one could really agree on that when trying to determine the more accurate (younger) age of the universe. Perhaps the expansion of space does not have this effect on visable light at exactly the speed of light and would encounter a problem being detected at great distances at some other velocity. It is just hard to base anything off of just one paper. I know a lot of people don't agree with the expansion of space causes doppler shift explaination, but it hasn't been proven wrong and was textbook when I was in High School, and it is still repeated by physicist on recent T.V. programs. I think there should still be some kind of truth to this.