Expansion different in different directions

[Strange]

18 minutes ago, Bmpbmp1975 said:

I had meant from this paragraph about fate 

“One of the pillars of cosmology – the study of the history and fate of the entire universe – is that the universe is ‘isotropic,’ meaning the same in all directions,” said Konstantinos Migkas of the University of Bonn in Germany, who led the new study. “Our work shows there may be cracks in that pillar.”

That is just defining what cosmology is: the study of the past and future evolution of the universe.

[Mordred]

The thing to understand about telescopes is that they have effective ranges. Chandra doesn't have the range of Planck or Hubble. The limitation is inherent in the wavelengths it has been designed to collect. It's primary goal is to collect data on our local region of spacetime. Of which it does an incredible job.

However one can have local anistropy without affecting the global distribution. Stars, galaxies etc are all examples.

In cosmology homogeneity and isotropy is only affective at scales of 100 Mpc. The Milky way galaxy is only between 460 to 720 kpc. Exact value is difficult to determine as we cannot see directly it's diameter.

 Our local group has several nearby anistropies such as the great attractor. This causes other side effects on luminosity measurements etc.

 For example there is a study our local region may be underdense due to the great attractor.

The first lesson a cosmologist learns is never trust a single dataset as fact. It is only after dozens of datasets come upon agreement do you develop a good confidence level by numerous independent studies and numerous independent equipment.

 

Edited April 8, 2020 by Mordred

[Bmpbmp1975]

The thing is we doN t know at what rates, one side can be normal and the other end can be expanding at a extreme, so may not be Tiny difference at all 

Edited April 8, 2020 by Bmpbmp1975

[Strange]

5 minutes ago, Bmpbmp1975 said:

The thing is we doN t know at what rates, one side can be normal and the other end can be expanding at a extreme, so may not be Tiny difference at all 

If it were a huge difference we would have known about it already. The differences that led to the discovery of dark energy (accelerating expansion) are already pretty small. So this must be smaller than that.

The current estimates of the Hubble constant (and hence age of the universe) are based on multiple measurements in all directions at many different distances. This anisotropy has not shown up before. Although, as they say, other more localised ones have.

[Bmpbmp1975]

2 minutes ago, Strange said:

If it were a huge difference we would have known about it already. The differences that led to the discovery of dark energy (accelerating expansion) are already pretty small. So this must be smaller than that.

The current estimates of the Hubble constant (and hence age of the universe) are based on multiple measurements in all directions at many different distances. This anisotropy has not shown up before. Although, as they say, other more localised ones have.

Oh so your saying our currently calculated information was from all sides and not just one side. Can it be that current sides recently changed there speeds 

[Strange]

9 minutes ago, Bmpbmp1975 said:

Can it be that current sides recently changed there speeds 

No.

[Bmpbmp1975]

According to this article the significance of difference is 30%
 

"Together with colleagues from the University of Bonn and Harvard University, we looked at the behaviour of over 800 galaxy clusters in the present Universe," says Konstantinos. "If the isotropy hypothesis was correct, the properties of the clusters would be uniform across the sky. But we actually saw significant differences."

properties, with similar temperatures, appeared to be less bright than what we would expect in one direction of the sky, and brighter than expected in another direction," says Thomas. "The difference was quite significant, around 30 percent. These differences are not random but have a clear pattern depending on the direction in which we observed in the sky

https://www.google.ca/amp/s/phys.org/news/2020-04-basic-assumption-universe.amp

[Strange]

11 minutes ago, Bmpbmp1975 said:

Can it be that current sides recently changed there speeds 

This is the universe we are talking about. "Suddenly" would mean "over many billions of years". The rate of expansion won't have changed overnight. Or just while these measurements were being made, and then back to normal afterwards.

3 minutes ago, Bmpbmp1975 said:

According to this article the significance of difference is 30%
 

"Together with colleagues from the University of Bonn and Harvard University, we looked at the behaviour of over 800 galaxy clusters in the present Universe," says Konstantinos. "If the isotropy hypothesis was correct, the properties of the clusters would be uniform across the sky. But we actually saw significant differences."

properties, with similar temperatures, appeared to be less bright than what we would expect in one direction of the sky, and brighter than expected in another direction," says Thomas. "The difference was quite significant, around 30 percent. These differences are not random but have a clear pattern depending on the direction in which we observed in the sky

https://www.google.ca/amp/s/phys.org/news/2020-04-basic-assumption-universe.amp

Interesting.

But note that is 30% difference in X-ray brightness. That almost certainly does not equate to 30% difference in expansion rate. 

I think need to wait for more results on this. It seems odd that this difference is only presence in the X-ray range.

[Bmpbmp1975]

7 minutes ago, Strange said:

This is the universe we are talking about. "Suddenly" would mean "over many billions of years". The rate of expansion won't have changed overnight. Or just while these measurements were being made, and then back to normal afterwards.

Interesting.

But note that is 30% difference in X-ray brightness. That almost certainly does not equate to 30% difference in expansion rate. 

I think need to wait for more results on this. It seems odd that this difference is only presence in the X-ray range.

Exactly my point, are standard tests don’t show it different ways but this better test shows the speed difference of expansion is 30% which is a major difference which will definitely effect our current understanding of the age and end of the universe drastically 

[michel123456]

The paper looks like a rewritten version of this one from the same author(s)

https://www.aanda.org/articles/aa/pdf/2018/03/aa31222-17.pdf

 

Edited April 8, 2020 by michel123456

[Strange]

1 minute ago, Bmpbmp1975 said:

Exactly my point, are standard tests don’t show it different ways but this better test shows the speed difference of expansion is 30% which is a major difference which will definitely effect our current understanding of the age and end of the universe drastically 

1. You don't know it is a "better test". It is a measurement that has never been made before. So we can't trust it until it has been validated by other people.

2. It doesn't show a speed difference of 30% (for the reasons I explained).

3. We have no idea if or how it will affect our models

4. Stop making up stuff that is not in the sources

[Bmpbmp1975]

I am just very confused on this paper, I am sorry. I have having trouble understanding the values and can’t tell if tiny or large.values.

[Strange]

1 minute ago, Bmpbmp1975 said:

I am just very confused on this paper, I am sorry. I have having trouble understanding the values and can’t tell if tiny or large.values.

I'm not surprised. I don't understand the paper. You would need to have studied astrophysics to understand it. 

[studiot]

12 minutes ago, michel123456 said:

The paper looks like a rewritten version of this one from the same author(s)

https://www.aanda.org/articles/aa/pdf/2018/03/aa31222-17.pdf

 

Well spotted +1

[Bmpbmp1975]

7 minutes ago, Strange said:

I'm not surprised. I don't understand the paper. You would need to have studied astrophysics to understand it. 

That’s why I was hoping someone here can make sense of the values

[michel123456]

On the below blog an explanation in more easy-to-grasp language. By the author.

https://chandra.harvard.edu/blog/node/754

[studiot]

3 hours ago, Bmpbmp1975 said:

Don’t understand 

3 minutes ago, Bmpbmp1975 said:

That’s why I was hoping someone here can make sense of the values

 

Don't worry in a couple of years (the blink of a cosmic eye) there will be a new study with different figures.

This was my earlier point.

[Bmpbmp1975]

8 minutes ago, studiot said:

 

Don't worry in a couple of years (the blink of a cosmic eye) there will be a new study with different figures.

This was my earlier point.

That’s depends on the values and if we’re still here. 

[michel123456]

Quote

 

The assumption of isotropy comes as a repercussion of the equations that describe the evolution of the cosmos, which are based on the theory of General Relativity. The main observational evidence for this is the CMB, which is the "picture" of the infant Universe when it had only 0.003% of its current age. The CMB seems to be isotropic, and cosmologists extrapolate this property of the very early Universe to our current epoch, nearly 14 billion years later. However, in about the last 4 billion years the so-called dark energy became the dominant element that drives the evolution of the Universe, constituting 70% of the latter's total content. Its baffling nature has not yet allowed astrophysicists to understand it properly. Therefore, assuming it to be isotropic is almost a leap of faith for now. This highlights the urgent need to investigate if today's Universe is isotropic or not.

There are several studies on this topic up to now, delivering contradictory results. Most use the observations of certain exploding stars (named supernovae), galaxies observed in the radio and infrared regime, quasars, etc. While some results show no significant evidence for deviation from the hypothesis of isotropy, others intriguingly indicate that a particular direction might expand slower than others. However, the confidence with which scientists identify this "anomaly" is not high enough to allow them to make robust conclusions about the isotropy of today's Universe.

For that reason, we need to come up with new, independent and powerful tests that will help us understand if the commonly-used assumption of isotropy still applies today. In 2018, we developed such a method that uses the largest — bound by gravity — objects in the Universe, namely galaxy clusters. As their name reveals, galaxy clusters are groups of tens to thousands of galaxies, with enormous quantities of ionized hot gas — containing atoms stripped of their electrons — between them. This gas emits strong radiation in X-rays and thus we can observe it by telescopes such as Chandra. Analyzing the spectra — the amount of X-rays measured at various energies — of the gas of each cluster, we can find its temperature (millions of Celsius/Fahrenheit degrees) and how bright the cluster is. Astronomers call this its luminosity. While we do not need to make any assumptions to measure the temperature, we do need to know a cluster’s distance to determine its luminosity. To find that, we assume we know the expansion rate of the Universe and that it is the same towards every sky direction.

And here is the catch: there is another way to estimate the luminosity of a galaxy cluster, without any strong cosmological assumptions. It is well known that there is a tight relationship between the temperature and the luminosity of a cluster. First we need to calibrate this relationship using the clusters from the entire sky and assuming the same expansion rate as before.

After that calibration, by measuring a cluster’s temperature we can obtain a good approximation of its luminosity, independent of its directly measured value. If the clusters of one sky region appear brighter or fainter than expected by average, we can evaluate if the expansion rate of the Universe towards this region is faster or slower than the one we assumed initially. Doing so for every direction in the sky, we can see if the expansion rate of the Universe looks the same everywhere. The assumed cosmology to initially calibrate our luminosity-temperature relation has no effect on our conclusions, since we are not looking for the absolute values of the expansion rate. Rather, we are just comparing different sky regions to one another.

In our first study in 2018, we came upon some intriguing results! That's why we decided to look into this more carefully and with more data. To do so, we analyzed 313 galaxy clusters using the Chandra and XMM-Newton telescopes and we combined them with 529 available clusters from previous studies. What we found was even more impressive than our 2018 results. We managed to pinpoint a region that seems to expand slower than the rest of the Universe, and one that seems to expand faster! Interestingly, our results agree with several previous studies that used other methods, with the difference that we identified this "anisotropy" in the sky with a much higher confidence and using objects covering the whole sky more uniformly.

So did we tear down one of the most crucial pillars of cosmology? Not so fast, it is not that simple. At least two scenarios may have led us to wrong conclusions.

Firstly, cosmic material might interfere with the light that travels from the clusters to the Earth. For example, previously unknown gas and dust clouds beyond the Milky Way could obscure a fraction of photons emitted from the clusters. Since we ignore the possible existence of such clouds, we do not account for their interference, and hence we would falsely underestimate the true luminosity of the clusters. Eventually, we could mistake this for a cosmological effect. We performed several tests that led us to believe that this scenario seems unlikely, but not impossible. However, considering that the direction of the anisotropy we find agrees with other studies that used observations in light at different wavelengths, where such obscuring effects are not expected, one could argue against the possibility of such biases in our analysis.

The second case is what we call "bulk flows". In a nutshell, some "superclusters" (groups of galaxy clusters!) exist that attract other clusters towards them through gravity. This can generate a coherent motion of some clusters (lying in the same sky region) towards a supercluster. But why is this important? Well, in our default analysis we assume that these “local” speeds of clusters, on top of the Universe’s expansion speeds, are small and random and that they do not matter in general. If this condition is not met, then our assumption does not hold. This might result in wrong distance (hence luminosity) estimations, producing "fake" cosmological anomalies. This scenario is not far-fetched and more tests are required to deliver a definite conclusion, although such large correlated speeds are not easily expected.

If none of the above is true, then the hypothesis of an isotropic Universe may be under question and a cosmological paradigm shift is possibly required. Of course for such a big change to occur, the astronomical community must perform other scrutinized tests obtaining consistent results every time.

The take-home message is this: the implications of this study could be profound either if a non-isotropic expansion of the Universe exists or if dominant bulk flow motion affects astronomers' measurements. Many studies in cosmology, including X-ray studies of galaxy clusters, assume that the Universe is isotropic and that correlated motions are not significant enough to consider them. Even if the mysterious gas and dust clouds are the origin of our results, the X-ray community might need to revisit their results, if their data were coming from that mysterious sky region

 

Taken from the blog. No values provided.

 

[Strange]

16 minutes ago, michel123456 said:

On the below blog an explanation in more easy-to-grasp language. By the author.

https://chandra.harvard.edu/blog/node/754

A few quotes from this:

Quote

We managed to pinpoint a region that seems to expand slower than the rest of the Universe, and one that seems to expand faster! Interestingly, our results agree with several previous studies that used other methods, with the difference that we identified this "anisotropy" in the sky with a much higher confidence and using objects covering the whole sky more uniformly.

So that sounds like it could be confirmation of something that was already observed.

But, science is never definite so:

Quote

So did we tear down one of the most crucial pillars of cosmology? Not so fast, it is not that simple. At least two scenarios may have led us to wrong conclusions.

...

If none of the above is true, then the hypothesis of an isotropic Universe may be under question and a cosmological paradigm shift is possibly required.

So, it is "maybe" and "if" and "more work required". In other words: science.

Note that there have been two(*) major paradigm shifts in cosmology in my lifetime. So a third one would be pretty exciting.

(*) Studiot said 5 in his lifetime, so either he is much older than me or is willing to accept smaller changes as "major"  

8 minutes ago, michel123456 said:

Taken from the blog. No values provided.

Please don't copy and paste almost entire articles:it potentially violates copyright.

[Bmpbmp1975]

2 minutes ago, Strange said:

A few quotes from this:

So that sounds like it could be confirmation of something that was already observed.

But, science is never definite so:

So, it is "maybe" and "if" and "more work required". In other words: science.

Note that there have been two(*) major paradigm shifts in cosmology in my lifetime. So a third one would be pretty exciting.

(*) Studiot said 5 in his lifetime, so either he is much older than me or is willing to accept smaller changes as "major"  

Don’t understand your comments strange 

[Strange]

1 minute ago, Bmpbmp1975 said:

Don’t understand your comments strange 

I'm not sure how to make it any simpler. How about: they might have important results or they might not. It would be exciting if they have. Is that clearer?

 

[Bmpbmp1975]

Just now, Strange said:

I'm not sure how to make it any simpler. How about: they might have important results or they might not. It would be exciting if they have. Is that clearer?

 

To me it sounds it’s bigger information that we think with possible bad outcomes for us 

[michel123456]

11 minutes ago, michel123456 said:

And here is the catch: there is another way to estimate the luminosity of a galaxy cluster, without any strong cosmological assumptions. It is well known that there is a tight relationship between the temperature and the luminosity of a cluster. First we need to calibrate this relationship using the clusters from the entire sky and assuming the same expansion rate as before.

After that calibration, by measuring a cluster’s temperature we can obtain a good approximation of its luminosity, independent of its directly measured value. If the clusters of one sky region appear brighter or fainter than expected by average, we can evaluate if the expansion rate of the Universe towards this region is faster or slower than the one we assumed initially

Maybe there is something in the concept: it looks a bit like circular thinking. Not sure though.

[MigL]

As Mordred has already explained, any dipole anisotropy is the result of our flow, or movement.

The best example I can think of is the red and blue spots, 180 degrees apart from each other, on the CMB map.
Once adjusted for our motion ( Earth around Sun, Sun around galaxy, galaxy towards Andromeda ) these spots disappear.
( red shift in the origin direction, and blue shift in the destination direction )

The flow, which even the authors suggest ( see quote from paper's conclusion, in my previous post ) might be galactic cluster flow, which means it is even smaller than the dipole anisotropy in the CMB, and not previously noted.


And after I gave Bmpbmp75 a +1 for finally getting 'serious', he reverts to his old ways...