The edge of significance

Sep 19, 2011 By Steve Nerlich, Universe Today
Two hemispheres of a spherical mapping of the cosmic microwave background. Credit: WMAP/NASA.

Some recent work on Type 1a supernovae velocities suggests that the universe may not be as isotropic as our current standard model (LambdaCDM) requires it to be.

The requires the to be isotropic and homogeneous – meaning it can be assumed to have the same underlying structure and principles operating throughout and it looks measurably the same in every direction. Any significant variation from this assumption means the standard model can’t adequately describe the current universe or its evolution. So any challenge to the assumption of isotropy and homogeneity, also known as the cosmological principle, is big news.

Of course since you are hearing about such a paradigm-shifting finding within this humble column, rather than as a lead article in Nature, you can safely assume that the science is not quite bedded down yet. The Union2 data set of 557 Type 1a , released in 2010, is allegedly the source of this latest challenge to the cosmological principle – even though the data set was released with the unequivocal statement that the flat concordance LambdaCDM model remains an excellent fit to the Union2 data.

Anyhow, in 2010 Antoniou and Perivolaropoulos ran a hemisphere comparison – essentially comparing supernova velocities in the northern hemisphere of the sky with the southern hemisphere. These hemispheres were defined using galactic coordinates, where the orbital plane of the Milky Way is set as the equator and the Sun, which is more or less on the galactic orbital plane, is the zero point.

Antoniou and Perivolaropoulos’ analysis determined a preferred axis of anisotropy – with more supernovae showing higher than average velocities towards a point in the northern hemisphere (within the same ranges of redshift). This suggests that a part of the northern sky represents a part of the universe that is expanding outwards with a greater acceleration than elsewhere. If correct, this means the universe is neither isotropic nor homogeneous.

However, they note that their statistical analysis does not necessarily correspond with statistically significant anisotropy and then seek to strengthen their finding by appealing to other anomalies in cosmic microwave background data which also show anisotropic tendencies. So this seems to be a case of looking at number of unrelated findings with common trends – that in isolation are not statistically significant – and then arguing that if you put all these together they somehow achieve a consolidated significance that they did not possess in isolation.

The galactic coordinate system. Credit: thinkastronomy.com

More recently, Cai and Tuo ran much the same hemispherical analysis and, not surprisingly, got much the same result. They then tested whether these data favoured one dark energy model over another – which they didn’t. Nonetheless, on the strength of this, Cai and Tuo gained a write up in the Physics Arxiv blog under the heading More Evidence for a Preferred Direction in Spacetime – which seems a bit of a stretch since it’s really just the same evidence that has been separately analysed for another purpose.

It’s reasonable to doubt that anything has been definitively resolved at this point. The weight of current evidence still favours an isotropic and homogeneous universe. While there’s no harm in mucking about at the edge of statistical significance with whatever limited data are available – such fringe findings may be quickly washed away when new data comes in – e.g. more Type 1a supernovae velocity measures from a new sky survey – or a higher resolution view of the cosmic microwave background from the Planck spacecraft. Stay tuned.

Explore further: Gravitational waves according to Planck

More information: - Antoniou and Perivolaropoulos. Searching for a Cosmological Preferred Axis: Union2 Data Analysis and Comparison with Other Probes.
- Cai and Tuo. Direction Dependence of the Deceleration Parameter.

add to favorites email to friend print save as pdf

Related Stories

Dark statistics

Mar 28, 2011

The hypothetical dark flow seen in the movement of galaxy clusters requires that we can reliably identify a clear statistical correlation in the motion of distant objects which are, in any case, flowing o ...

Backgrounds

Jun 28, 2011

You’ve probably heard of the cosmic microwave background, but it doesn’t stop there. The as-yet-undetectable cosmic neutrino background is out there waiting to give us a view into the first seconds ...

SLoWPoKES

May 16, 2011

The Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES) catalog was recently announced, containing 1,342 common proper motion pairs (i.e. binaries) – which are all low mass stars in the ...

Recommended for you

Gravitational waves according to Planck

4 hours ago

Scientists of the Planck collaboration, and in particular the Trieste team, have conducted a series of in-depth checks on the discovery recently publicized by the Antarctic Observatory, which announced last spring that it ...

Infant solar system shows signs of windy weather

4 hours ago

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have observed what may be the first-ever signs of windy weather around a T Tauri star, an infant analog of our own Sun. This may help ...

Finding hints of gravitational waves in the stars

11 hours ago

Scientists have shown how gravitational waves—invisible ripples in the fabric of space and time that propagate through the universe—might be "seen" by looking at the stars. The new model proposes that ...

How gamma ray telescopes work

12 hours ago

Yesterday I talked about the detection of gamma ray bursts, intense blasts of gamma rays that occasionally appear in distant galaxies. Gamma ray bursts were only detected when gamma ray satellites were put ...

The frequency of high-energy gamma ray bursts

14 hours ago

In the 1960s a series of satellites were built as part of Project Vela.  Project Vela was intended to detect violations of the 1963 ban on above ground testing of nuclear weapons.  The Vela satellites were ...

User comments : 22

Adjust slider to filter visible comments by rank

Display comments: newest first

theon
1 / 5 (12) Sep 19, 2011
Now that it appears that the CDM does not exist (and thus not seen at the LHC) we must go back to a more modest picture: DM from baryons in the Galaxy and from neutrinos in galaxy clusters. Actually, LCDM could never have explained the ubiquitous 15 K "cold dust" temperature, and neither the very frequent "mysterious radio events". To explain them, one needs the MACHO dark matter observed in quasar micolensing.
Deadbolt
5 / 5 (9) Sep 19, 2011
No, if CDM does not exist, then we have to find out what does, not just make stuff up.
GreyLensman
4.9 / 5 (21) Sep 19, 2011
I love the tone of this article. Physorg could do with more of this editorial realism - otherwise you could get the impression that cancer is cured 30 times a week, massively established physics theories are overthrown six times a month, solar power reaches commercial viability every second day and batteries have become so efficient that we can run jumbo jets from our cell phone. No wonder this site is a magnet for cranks.
omatranter
4.1 / 5 (23) Sep 19, 2011
"Its reasonable to doubt that anything has been definitively resolved at this point. The weight of current evidence still favours an isotropic and homogeneous universe."

Yes Yes finally proof of Repulsive Neutrons!
Early in my research I thought that it was just me the the Universe was expanding (running) away from, due to the nature of my private life.
But after much drinking and hallucinogenics I came to the undeniable conclusion its not my personnel hygiene that responsible for the Expansion of the universe but, you guessed it my well versed quislings, Repulsive Neutrons, they literally can't stand being near me, I mean each other and will actually spontaneously annihilate top get away, leaving no evidence of them ever having been, this make it hard to disprove that they weren't even their to begin with.

IF I'm not in jail I hope to see you at
NAMBLA "Neutron Abhorrents Mandated By Laughable Assertions" in Oct

Neutron Repulsion: Boyah!

Oliver has left the Building
Shootist
1 / 5 (5) Sep 19, 2011
Now that it appears that the CDM does not exist


CDM? Like planets, asteroids, comets, dust, gas, Y-class dwarf stars, and most everything else moving at non-relativistic speeds; which neither shine, nor reflect enough light to be seen (the gravitational influence of which is apparently measurable)? Is this the cold dark matter that doesn't exist?

El_Nose
4.8 / 5 (12) Sep 19, 2011
@omar

LOL -- that was a a funny post

@Steve Nerlich

awesome article -- its humble and thoughtful, even if you aren't the way the article is written you sound knowledgable about the subject. You avoid errors by fully qualiofy statements -- i love the fact that you state
ince you are hearing about such a paradigm-shifting finding within this humble column, rather than as a lead article in Nature, you can safely assume that the science is not quite bedded down yet.


that right there speaks more intelligence written into a science article than 9 out 10 you find here on Physorg.com

I hope to read more articles by you.
that_guy
2 / 5 (1) Sep 19, 2011
@ omat & greylens - I would give you both 50 stars each if I could.

As far as the article is concerned - I don't expect anyone to agree with my opinion, but in my mind, this actually more supports the big bang. I always wondered why we would have a singular big bang, and yet have essentially the same view in every direction - It is very unlikely that we would be dead center, or that all places would have a statistically identical view. You would or should expect some kind of anomoly from one side to the other. (I understand the reasons why conventional theory is different with my opinion, but I disagree with it)

I think they'll reconsider how the geometry of the universe/big bang works - and possibly take two steps forward after this one step back.
Husky
5 / 5 (1) Sep 19, 2011
if this is true than one would expect lower average gas densities /literally stretched supply in the faster expanding part and thus less material inside a given cubic astronomical unit to build second/third generation stars from, so we would count less overall stars in this alledged faster expanding hemisphere (?) also one should have bigger average void sizes between the clusters, but especially the filaments, they stretch over such vast distances (and time) that difference in void sizes would be statistically significant
GSwift7
2 / 5 (1) Sep 19, 2011
So this seems to be a case of looking at number of unrelated findings with common trends that in isolation are not statistically significant and then arguing that if you put all these together they somehow achieve a consolidated significance that they did not possess in isolation


That sounds awefully familiar from some other field of study.
MorituriMax
5 / 5 (3) Sep 19, 2011
theon mumbled,
Now that it appears that the CDM does not exist (and thus not seen at the LHC)...

Dude, did you even read the whole thing? >>"Its reasonable to doubt that anything has been definitively resolved at this point. The weight of current evidence still favours an isotropic and homogeneous universe."
Decimatus
1 / 5 (1) Sep 19, 2011
Nice to finally see a picture of the direction of the supposed expansion. Too bad it didn't line up directly with the core.
Callippo
1 / 5 (6) Sep 19, 2011
In dense aether theory the Universe is random and it would appear like fractal clouds or Perlin noise. Because we can observe only subtle portion of this stuff, it appears quite homogeneous. I'm often comparing the Universe to water surface, but there is no reason for having such surface completely flat - the Occam's criterion requires to assume nothing special about our Universe at the very general scale. For example, Laura Mersini describes the observable Universe like giant quantum wave, which is traveling from place to place.

The cosmological principle implies, we aren't sitting in any special place of Universe, which would mean, the symmetry of omnidirectional space-time expansion must be violated too - and it actually is, as follows from Doppler's anisotropy of CMBR. In addition, recently we observed the anisotropy in fine structure constant distribution, the WMAP cold spot, the axis of dark flow etc. It would be interesting to correlate all these asymmetries together.
Robert_Wells
5 / 5 (5) Sep 19, 2011
is it just me or is comments section here on physorg becoming more and more like a high school hallway in regards to drama?

btw i lawl'd
Decimatus
5 / 5 (3) Sep 19, 2011
is it just me or is comments section here on physorg becoming more and more like a high school hallway in regards to drama?

btw i lawl'd


Jennifer: Oh my gawd! Did you hear what Stacy said about Neutron Repulsion?!?

Amanda: Oh no she didn't! *snap* *snap* *snap*
Callippo
1.8 / 5 (5) Sep 19, 2011
massively established physics theories are overthrown six times a month
IMO it's not only result of journalism - but the current epoch of physics and reality understanding will lead into such a situation undeniably. We can compare it to the experience at the water surface, when observed with its own ripples: at proximity it appears chaotic due the Brownian noise, but after then the spreading of ripples becomes regular and independent to background, so we can apply deterministic theories on it.

Just at the whole boundary of the visibility scope all surface waves will break and disperse into fuzzy underwater again. The progress in technology has enabled us to see these fuzzy boundaries of observable reality right now and most of deterministic theories are getting violated again. Maybe I'm wrong, but I don't think, we could still reveal something interesting behind it, I mean something other than just fuzzy randomness. We are creatures lost in fractal landscape covered with fog.
frajo
1 / 5 (2) Sep 20, 2011
you could get the impression that cancer is cured 30 times a week, massively established physics theories are overthrown six times a month, solar power reaches commercial viability every second day and batteries have become so efficient that we can run jumbo jets from our cell phone. No wonder this site is a magnet for cranks.
I doubt the crank density at PhysOrg is higher than the society-wide and the global crank densities.

The paradigm of a "massively established physics theory that seems to be overthrown six times a month" is just a well justified PoV wrt the SM. But nobody refutes that serious questions remain to be unanswered by the SM. (See the wikipedia entry "Open questions in physics".)
Thus another PoV, namely "six times a month we find another crack in the SM", seems to be justified as well.
See, e.g., Subir Sarkar's paper "Astroparticle Physics, Cosmology and Dark Matter" at physics.ntua.gr/corfu2011/lectures.html on homogeneity (Slides 1).
hard2grep
1 / 5 (1) Sep 20, 2011
Who wants to be hung for burying the Standard Model? This is the "inverse square" of times that I have heard about nonuniform velocities in the northern hemisphere.I am hoping that this is not an effect caused by our orientation,orbital path, or other such relativistic predators. The expansion of the universe is scalar, not directional. Right now, I do not have the locations of the measured objects but this could just be inflation at an odd scale( while the universe is supposedly approximately equal over-all, it is by no means uniform at all scales.
hard2grep
1 / 5 (1) Sep 20, 2011
Did anyone notice that our view of that hemisphere is right over the center of our highly massive galactic center?

Did they use Doppler shift methods?
El_Nose
5 / 5 (2) Sep 20, 2011
there is probably something effecting our field of view in that direction that we have yet to identify
gimpypoet
1 / 5 (1) Sep 24, 2011
to think that any explosion would spread evenly from the epicenter is flawed. no explosion i have ever heard of acts in that manner. why should the big bang be any different? if matter is spread out in generally the plane, or the longitudinal axis, where is the matter in the latitudinal? was the singularity the the big bang started from oddly shaped. if so, the the pressure forcing it together in the first place could not have been even, thus no ball of pre matter, but a disk or flattened ball exploded, which would spread from the singularity unevenly, thus no symetry in the first place. no "explosion" could result in a perfect spherical expansion, so no symetry before the secondary expansion either, and none could be observed today.we can't find the center of the universe because there is no center point for the big bang, and it was not homogenious at the start, can't be now.
gimpypoet
1 / 5 (1) Sep 24, 2011
since we can never prove or disprove the start of the 'verse, we will never know when it will end, and does it even matter? only thing that could possibly matter is the present and immeadiate future. the past is great to learn from, but can't be changed. the future can be predicted to some degree, and can be manipulated to so degree. this proves symetry false for in that time is not symetrical, and for us flows only in one direction.again proving symetry false. can not be uni-directional for us so there will never be a contraction of the universe either.think about it and use what you know to be true. you cant head off in one direction into the 'verse and end up back at the point of origin, period.
gimpypoet
1 / 5 (1) Sep 24, 2011
if any of my statements seem in opposition to the sm, perhaps the newly realised possibilities that something is faster than light has some merrit. I'm still puzzled that if einsteins bus was traveling at the speed of light and the lights were turned on would they light the way theory. would the photons stand still? if the bus was only going 95% would the light spread out if front of the bus slower than if the bus were stopped? of course gr is still a theory, so any one can posit an idea and call it a theory. if so, could you prove it right or wrong? locking ones self into a single frame of mind is not what Einstein did and people today seem deadset on thinking GR, AGW, lcmd or any other theory is unalterable, but that is the basis of the scientific method. theory, hypothis, experiments to prove/disprove, narrowing down the facts, then proof. even newtons "laws" are still theory is not proven, still is a theory. so is this web site a page of theories or proof? unknown for now!