Surprise! The universe's expansion rate may vary from place to place

These four galaxy clusters were among hundreds analyzed in a large survey to test whether the universe is the same in all directions over large scales. The study results suggest the concept of an "isotropic" universe may not entirely fit. (Image credit: NASA/CXC/Univ. of Bonn/K. Migkas et al.)

The universe may not be the same in every direction after all.

The expansion rate of the universe appears to vary from place to place, a new study reports. This finding, if confirmed, would force astronomers to reassess just how well they understand the cosmos.

"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," study lead author Konstantinos Migkas, of the University of Bonn in Germany, said in a statement. "Our work shows there may be cracks in that pillar."

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The universe has been expanding continuously for more than 13.8 billion years, ever since the Big Bang — and at an accelerating rate, thanks to a mysterious force called dark energy. Equations based on Einstein's general theory of relativity suggest that this expansion is isotropic on large spatial scales, Migkas wrote Tuesday (April 7) in a blog post about the new study.

Observations of the cosmic microwave background (CMB), the universe-pervading radiation left over from the Big Bang, support this notion, he added: "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."

But it's unclear how valid this extrapolation is, he stressed, noting that dark energy has been the dominant factor in the universe's evolution over the last 4 billion years or so. Dark energy's "baffling nature has not yet allowed astrophysicists to understand it properly," Migkas wrote. "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."

The new study reports the results of one such investigation. Migkas and his colleagues studied 842 galaxy clusters, the largest gravitationally bound structures in the universe, using data gathered by three space telescopes: NASA's Chandra X-ray Observatory, Europe's XMM-Newton and the Advanced Satellite for Cosmology and Astrophysics, a joint Japanese-U.S. mission that ended in 2001.

The researchers determined the temperature of each cluster by analyzing the X-ray emissions coming from huge fields of hot gas within them. They used this temperature information to estimate each cluster's inherent X-ray luminosity, without needing to take into account cosmological variables such as the universe's expansion rate.

The researchers then calculated X-ray luminosity for each cluster in a different way, one that did require knowledge of the universe's expansion. Doing so revealed apparent expansion rates across the entire sky — and these rates didn't match up everywhere.

"We managed to pinpoint a region that seems to expand slower than the rest of the universe, and one that seems to expand faster!" Migkas wrote in the blog post. "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."

This graphic shows a map of the universe's expansion rates in different directions, estimated in a new study by Konstantinos Migkas and collaborators. The map is in galactic coordinates, with the center looking toward the center of our galaxy. The black and purple colors show the directions of the lowest expansion rates (the Hubble constant); yellow and red show the directions of the highest expansion rates. (Image credit: University of Bonn/K. Migkas et al.)

It's possible that this result has a relatively prosaic explanation. For example, perhaps galaxy clusters in the anomalous areas are being pulled hard gravitationally by other clusters, giving the illusion of a different expansion rate.

Such effects are seen at smaller spatial scales in the universe, the researchers said. But the new study probes clusters up to 5 billion light-years away, and it's unclear if gravitational tugs could overwhelm expansion forces over such vast distances, they added.

If the observed expansion-rate differences are indeed real, they could reveal intriguing new details about how the universe works. For instance, maybe dark energy itself varies from place to place throughout the cosmos.

"It would be remarkable if dark energy were found to have different strengths in different parts of the universe," study co-author Thomas Reiprich, also of the University of Bonn, said in the same statement. "However, much more evidence would be needed to rule out other explanations and make a convincing case."

The new study appears in the April 2020 issue of the journal Astronomy and Astrophysics. You can read it for free at the online preprint site arXiv.org.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

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25 Comments Comment from the forums

Torbjorn Larsson

Admin said:
The expansion rate of the universe appears to vary from place to place, a new study reports. This finding, if confirmed, would force astronomers to reassess just how well they understand the cosmos.

These types of anisotropies in isolated data sets have been reported numerous times, and the uniform LCDM cosmology has survived. The main reason is that integrated data syntheses such as the Planck group do removes or alleviate them.

While it is technically true that the data probe further out, the main data is extremely local, < 1 Glyrs radius (z < 0.1). It is mostly < 10 % nonuniformity and less than the necessary 5 sigma significance at that. They will add more data, which presumably will move the probe further out as well, which will be interesting.
Reply
rod

I think the cosmology department needs a *fact* check for many of the claims commonly presented to the public :) Here is another report on this rate of expansion problem, Rethinking cosmology: Universe expansion may not be uniform (Update) The report stated, "Astronomers have assumed for decades that the Universe is expanding at the same rate in all directions. A new study based on data from ESA's XMM-Newton, NASA's Chandra and the German-led ROSAT X-ray observatories suggests this key premise of cosmology might be wrong... Widely accepted as a consequence of well-established fundamental physics, the hypothesis has been supported by observations of the cosmic microwave background (CMB). A direct remnant of the Big Bang, the CMB reflects the state of the Universe as it was in its infancy, at only 380 000 years of age. The CMB's uniform distribution in the sky suggests that in those early days the Universe must have been expanding rapidly and at the same rate in all directions. In today's Universe, however, this may no longer be true. "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."

Note, the origin of the CMB and redshift used to explain the evolution of the cosmic fireball that created the universe, the uniform or nearly uniform temperature observed in the CMBR today is interpreted to mean *must have been expanding rapidly and at the same rate in all directions. In today's Universe, however, this may no longer be true."

What? This should raise questions here about the various rates of expansion used in cosmology and how these different expansion rates are confirmed. The CMBR uniformity today is considered to represent a redshift where z=1000 or more based upon the expansion rate and size of the universe. However, galaxies with high redshifts are spectral measurements, the CMBR redshift is not, it is an extrapolation dependent on the rate of expansion, this seems to be different now. This is not the same as spectra obtained for high redshift galaxies, but a model dependent interpretation for the redshift or z. For example, ‘Characterizing the Environment Around The Most Distant Known Galaxy’, https://ui.adsabs.harvard.edu/abs/2019hst..prop15977O/abstract, “The discovery of the very luminous galaxy GN-z11 at only 400 Myr after the Big Bang in the GOODS-North field with an HST grism spectroscopic redshift of z=11.1+/-0.1 presents a real puzzle for early Universe science. Its detection raises significant questions about our understanding of early galaxy formation…”

I note a difference here. *spectroscopic redshift* vs. the model dependent interpretation of original temperature some 3000K vs. near 3K today for the CMBR where z=1000 or more.

The latest report on expansion rate published, now we read that the rate of expansion used to calculate the z number for the CMBR redshift, the expansion rate may not be uniform and changed. Seems like z=1000 or more may not be confirmed, certainly not confirmed using the same method as GN-z11 redshift.
Reply
rod

FYI, one more note here. From a source that sent me this information about the formation of the CMBR, "The "surface of last scattering" is a sound physical concept in that in a hot plasma the radiation is constantly interacting with the plasma, where everything is electrically charged - Thompson scattering. However, once the assumed fireball has cooled sufficiently, electrons begin to bind to atomic nuclei and thus form neutral atoms, allowing photons to pass freely - a stage known as decoupling, which corresponds to a temperature of about 3,000 K. Within the standard BB paradigm, the light first radiated from this process is now seen as the Cosmic Microwave Background. Thus the z~1000+ redshift figure is partly based on well-established physics, and partly on the BB paradigm."

The expansion rate used to calculate the redshift from *surface of last scattering* is different now or presently measured different in the universe than what is used in BB model. The CMBR redshift could be less or even more or perhaps no redshift for the cosmic fireball evolution :)
Reply
dfjchem721

You know rod, the Department of Cosmology's rec room has a dart board, with your picture on it. Have heard it is used quite frequently!

I don't recall any of these posts mentioning Dark Energy (DE) - probably not required from the debate perspective. It would seem that DE, which was "invented" to explain increasing in expansion rate, would have to be asymmetric in its distribution if this new interpretation is correct. I suspect this is why it suggests that the hypothesis of DE and/or the entire BB needs re-evaluation. After all, BB cosmology is based on symmetry in all aspects, unless I am mistaken. Of course there could always be some other form of matter/energy we are unaware of, or have not yet invented, on which the expansion is superimposed, which imparts asymmetry (if this story is accurate).

In one of the greatest understatements I ever read, from the article :

"Dark energy's "baffling nature has not yet allowed astrophysicists to understand it properly," Migkas wrote. "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.""

Assuming it is real, anything but isotropic DE would need a leap in faith, since it is presumed to be the largest part of the mass-energy of the universe. If it is not isotropic, someone has some very serious explaining to do, or so it seems to me.

Just watch out for rod. The dart board only gives him more ammo for counter-attacks. Have at 'em.

Do I sound like early-stage dementia, or is the physics getting jumbled up by data overload?
Reply
Xinhang Shen

Admin said:
The expansion rate of the universe appears to vary from place to place, a new study reports. This finding, if confirmed, would force astronomers to reassess just how well they understand the cosmos.

Surprise! The universe's expansion rate may vary from place to place : Read more
Of course, the expansion is not isotropic because its theoretical base - Einstein's relativity is wrong. Firstly, it should not be called the expansion of "the universe", but the expansion of the visible part of the universe because we can never claim anything about the entire universe which is defined as the collection of everything without boundaries.

Secondly, Einstein's relativity has already been disproved both theoretically and experimentally (see https://www.researchgate.net/publication/297527784_Challenge_to_the_Special_Theory_of_Relativity ). The most well-known experimental evidence is that the time of GPS is absolute because all atomic clocks on the GPS satellites are synchronized to show the same absolute time relative to all reference frames (ground, each satellite, etc), while special relativity tells us that time is relative and clocks can never be synchronized relative to more than one inertial reference frame. Therefore, time is absolute without beginning and end, and independent of the three dimensional space which does not have boundaries. It is non-sense to talk about the age of the universe. At most, we can only talk about the time from the beginning of the current expansion of the visible part of the universe.

Thirdly, the visible part of the universe is a collection of celestial objects (galaxies, clusters of galaxies, etc) which seem in a process of periodical cycles of implosion driven by gravitation and explosion driven by the pressure of aether. It seems that we are currently in the accelerating expansion stage of an explosion. Just like the explosion of a bomb, the expansion of the visible part of the universe should never be isotropic.
Reply
ty2010b

Xinhang Shen said:
Of course, the expansion is not isotropic because its theoretical base - Einstein's relativity is wrong. Firstly, it should not be called the expansion of "the universe", but the expansion of the visible part of the universe because we can never claim anything about the entire universe which is defined as the collection of everything without boundaries.

Secondly, Einstein's relativity has already been disproved both theoretically and experimentally (see https://www.researchgate.net/publication/297527784_Challenge_to_the_Special_Theory_of_Relativity ). The most well-known experimental evidence is that the time of GPS is absolute because all atomic clocks on the GPS satellites are synchronized to show the same absolute time relative to all reference frames (ground, each satellite, etc), while special relativity tells us that time is relative and clocks can never be synchronized relative to more than one inertial reference frame. Therefore, time is absolute without beginning and end, and independent of the three dimensional space which does not have boundaries. It is non-sense to talk about the age of the universe. At most, we can only talk about the time from the beginning of the current expansion of the visible part of the universe.

Thirdly, the visible part of the universe is a collection of celestial objects (galaxies, clusters of galaxies, etc) which seem in a process of periodical cycles of implosion driven by gravitation and explosion driven by the pressure of aether. It seems that we are currently in the accelerating expansion stage of an explosion. Just like the explosion of a bomb, the expansion of the visible part of the universe should never be isotropic.

"After a Lorentz transformation from a moving inertial reference frame to a stationary inertial reference frame, the time in the moving frame is dilated by a factor γ , but the frequency of a clock in the moving frame decreases by the same factor γ , leaving the resulting product (i.e., the time displayed by the moving clock) unchanged. " - this is describing the same effect, even if they were independent they'd be additive, not offsetting.

GPS times are compensated for relativity http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.htmlAs well as other factors https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4570298/
Reply
Torbjorn Larsson

rod said:
I think the cosmology department needs a *fact* check for many of the claims commonly presented to the public :) Here is another report on this rate of expansion problem, Rethinking cosmology: Universe expansion may not be uniform (Update) The report stated, "Astronomers have assumed for decades that the Universe is expanding at the same rate in all directions. A new study based on data from ESA's XMM-Newton, NASA's Chandra and the German-led ROSAT X-ray observatories suggests this key premise of cosmology might be wrong... Widely accepted as a consequence of well-established fundamental physics, the hypothesis has been supported by observations of the cosmic microwave background (CMB). A direct remnant of the Big Bang, the CMB reflects the state of the Universe as it was in its infancy, at only 380 000 years of age. The CMB's uniform distribution in the sky suggests that in those early days the Universe must have been expanding rapidly and at the same rate in all directions. In today's Universe, however, this may no longer be true. "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."

Note, the origin of the CMB and redshift used to explain the evolution of the cosmic fireball that created the universe, the uniform or nearly uniform temperature observed in the CMBR today is interpreted to mean *must have been expanding rapidly and at the same rate in all directions. In today's Universe, however, this may no longer be true."

What? This should raise questions here about the various rates of expansion used in cosmology and how these different expansion rates are confirmed. The CMBR uniformity today is considered to represent a redshift where z=1000 or more based upon the expansion rate and size of the universe. However, galaxies with high redshifts are spectral measurements, the CMBR redshift is not, it is an extrapolation dependent on the rate of expansion, this seems to be different now. This is not the same as spectra obtained for high redshift galaxies, but a model dependent interpretation for the redshift or z. For example, ‘Characterizing the Environment Around The Most Distant Known Galaxy’, https://ui.adsabs.harvard.edu/abs/2019hst..prop15977O/abstract, “The discovery of the very luminous galaxy GN-z11 at only 400 Myr after the Big Bang in the GOODS-North field with an HST grism spectroscopic redshift of z=11.1+/-0.1 presents a real puzzle for early Universe science. Its detection raises significant questions about our understanding of early galaxy formation…”

I note a difference here. *spectroscopic redshift* vs. the model dependent interpretation of original temperature some 3000K vs. near 3K today for the CMBR where z=1000 or more.

The latest report on expansion rate published, now we read that the rate of expansion used to calculate the z number for the CMBR redshift, the expansion rate may not be uniform and changed. Seems like z=1000 or more may not be confirmed, certainly not confirmed using the same method as GN-z11 redshift.

I'm not sure if you are picking nits, but the cosmic background radiation black body spectra has a peak and a temperature (which are correlated). So when we say that it was produced at z ~1000, it is based on the plasma black body temperature then (T ~3,000 K) and the CMB black body temperature now (T ~ 3 K) - the photons in the spectra have been stretched a factor 1,000 during their travel due to the universe having expanded that much. It is done by observing spectra, even if they have no spectroscopic lines. (But technically the many antenna filters in the Planck observatory did a spectroscopic decomposition, so again, your terminological mileage may vary.)

In any case, this result will most likely be met with the same shrug I gave it. Maybe the tension will be over 5 sigma when they go another round of data collection, maybe not. Maybe they can integrate more data and be more convincing, maybe not. Maybe a 10 % nonuniformity is problematic, maybe not. (I don't think they studied that.)
Reply
Torbjorn Larsson

dfjchem721 said:
You know rod, the Department of Cosmology's rec room has a dart board, with your picture on it. Have heard it is used quite frequently!

I don't recall any of these posts mentioning Dark Energy (DE) - probably not required from the debate perspective. It would seem that DE, which was "invented" to explain increasing in expansion rate, would have to be asymmetric in its distribution if this new interpretation is correct. I suspect this is why it suggests that the hypothesis of DE and/or the entire BB needs re-evaluation. After all, BB cosmology is based on symmetry in all aspects, unless I am mistaken. Of course there could always be some other form of matter/energy we are unaware of, or have not yet invented, on which the expansion is superimposed, which imparts asymmetry (if this story is accurate).

In one of the greatest understatements I ever read, from the article :

"Dark energy's "baffling nature has not yet allowed astrophysicists to understand it properly," Migkas wrote. "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.""

Assuming it is real, anything but isotropic DE would need a leap in faith, since it is presumed to be the largest part of the mass-energy of the universe. If it is not isotropic, someone has some very serious explaining to do, or so it seems to me.

Just watch out for rod. The dart board only gives him more ammo for counter-attacks. Have at 'em.

Do I sound like early-stage dementia, or is the physics getting jumbled up by data overload?

On the contrary, few cosmologists entertain these notions, it is all in the public meme sector. The statement you refer to is a severe overstatement as far as I can see, dark energy nature is not baffling as much as its value was (and there are explanations for that now), and cosmological homogeneity and isotropy has been well studied from the start of modern cosmology.

I refer to Wikipedia om the history of dark energy and to my comment on the isotropy results in context.
Reply
Torbjorn Larsson

Xinhang Shen said:
Of course, the expansion is not isotropic because its theoretical base - Einstein's relativity is wrong. Firstly, it should not be called the expansion of "the universe", but the expansion of the visible part of the universe because we can never claim anything about the entire universe which is defined as the collection of everything without boundaries.

Secondly, Einstein's relativity has already been disproved both theoretically and experimentally (see https://www.researchgate.net/publication/297527784_Challenge_to_the_Special_Theory_of_Relativity ). The most well-known experimental evidence is that the time of GPS is absolute because all atomic clocks on the GPS satellites are synchronized to show the same absolute time relative to all reference frames (ground, each satellite, etc), while special relativity tells us that time is relative and clocks can never be synchronized relative to more than one inertial reference frame. Therefore, time is absolute without beginning and end, and independent of the three dimensional space which does not have boundaries. It is non-sense to talk about the age of the universe. At most, we can only talk about the time from the beginning of the current expansion of the visible part of the universe.

Thirdly, the visible part of the universe is a collection of celestial objects (galaxies, clusters of galaxies, etc) which seem in a process of periodical cycles of implosion driven by gravitation and explosion driven by the pressure of aether. It seems that we are currently in the accelerating expansion stage of an explosion. Just like the explosion of a bomb, the expansion of the visible part of the universe should never be isotropic.

No other theory for gravity has stood up as well as Einstein's general relativity, which is why relativistic LCDM is reigning. The contenders are mostly dead: https://www.quantamagazine.org/troubled-times-for-alternatives-to-einsteins-theory-of-gravity-20180430/ .

"New observations of extreme astrophysical systems have “brutally and pitilessly murdered” attempts to replace Einstein’s general theory of relativity."

"Many researchers knew that the merger would be a big deal, but a lot of them simply “hadn’t understood their theories were on the brink of demise,” he later wrote in an email. In Saclay, he read them the last rites. “That conference was like a funeral where we were breaking the news to some attendees.”"

Your points are really not problematic for cosmology.

- LCDM models the entire universe, since 1) there is no known reason not to and 2) it is more likely compared to any constrained version in a likelihood ratio test.
- Your reference is self promotion. It is an essay of "examination" in something that looks like a shoddy philosophical journal (refers to "views" rather than to references and testing), not a research paper. It's possibly even a predatory "journal" since it is been discontinued from data bases several times https://en.wikipedia.org/wiki/Physics_Essays ] and is now listed in "Emerging Sources Citation index" which is described as containing predatory journals https://en.wikipedia.org/wiki/Emerging_Sources_Citation_Index ]. And I note, it isn't describing relativity at all, since it doesn't use the defining property of clocks - frequency stability. See more on that in ty2010b comment.
- The last claim of error in relativity doesn't seem to make any sense, especially in relation to relativity (which famously has no "aether"). It all depends on scale - galaxies are too small to affect cosmology, galaxy clusters lives in cosmic filaments that are still condensing from gravity over time, the universe is and has always been expanding - so it is hard to extract any overall "cycles". Except on universe scale, which as I noted has none. LCDM says it can't have cycles with the content of our universe being as it is (the inner state decides expansion rates), and all our observations agree.

To sum up, you propose to replace the last century of well founded, well tested physics advance with a non founded claim that Newtonian physics is better (it isn't - it is more restricted), and an erroneous understanding of universe expansion: the universe is expanding in every volume, so it can't have a center or be "an explosion". As they say, big bang was a point in time, not a point in space. It is impossible to make that switch back, it can't explain what we see. C.f. how you don't make sense in regards to cosmological expansion, or to the universal speed limit (light speed in vacuum).
Reply
dfjchem721

T, surely you would not want this to be an echo chamber. What would you debate? My advisor told me early on to always listen to potential variations from your own ideas and models. No one can be right about everything!

And could you be as brief as possible (sparing your time) about "On the contrary, few cosmologists entertain these notions, it is all in the public meme sector. "? Like maybe top five on your hit list of meme nonsense.
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