Recent measurements suggest the universe it is flat and infinite

[Alan McDougal]

http://www.space.com...map-aas223.html

Recent measurements suggest the universe it is flat and infinite

The new results, presented by Schlegel and his colleagues here today (Jan. 8) at the 223rd meeting of the American Astronomical Society, also provide one of the best-ever determinations of the curvature of space, researchers said. In short, the universe appears to be quite "flat," meaning that its shape can be described well by Euclidean geometry, in which straight lines are parallel and the angles in a triangle add up to 180 degrees.

"One of the reasons we care is that a flat universe has implications for whether the universe is infinite," Schlegel said. "That means — while we can't say with certainty that it will never come to an end — it's likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinite universe."


BOSS astronomers use a spectrograph on the Sloan Foundation's 2.5-meter telescope at Apache Point Observatory in New Mexico to make their observations.

"On a clear night when everything goes perfectly, we can add more than 8,000 galaxies and quasars to the map," Kaike Pan, who leads the team of observers working with the spectrograph, said in a statement.

The team has presented other results from the galaxy survey. However, the new map extends the survey's reach, more than doubling the size of the examined area and thereby allowing for more precise measurements. The newly presented data also include earlier results that surveyed nearby galaxies, BOSS officials said.

"Making these measurements at two different distances allows us to see how the expansion of the universe has changed over time, which will help us understand why it is accelerating," explained University of Portsmouth astronomer Rita Tojeiro, who co-chairs the BOSS galaxy clustering working group along with Jeremy Tinker of New York University.

The new results should help lay the foundation for even more-precise measurements in the coming years, Schlegel said.

"Future surveys will be doing more of this, both filling in this map of the universe, [and] the enormous volume of the universe we have yet to map out and doing this with even higher precision," Schlegel said here today at the AAS meeting.


Interesting?

 

[bapowell]

There is no implication of the universe being infinite. Remember these inferences pertain to the observable universe only! We can only speak of local, not global, flatness and we have no empirical knowledge of the size of the universe outside the Hubble sphere.

 

[marcus]

Alan, I tried your link to "space.com" and it did not work. I think the link you wanted to paste into your post was:
http://www.space.com/24207-dark-energy-galaxy-map-aas223.html

I generally agree with Brian Powell's comment about no logical implication of infinite spatial extent. The article quoted saying their results were "consistent with" infinite extent, zero overall mean spatial curvature. But consistent with simply means "does not contradict" or "does not rule out".

Studies like this usually publish a 95% confidence interval for an estimated mean curvature parameter or equivalently an estimated mean density ratio to the critical density that corresponds to zero curvature. The trend is for these published confidence intervals to be narrowing down AROUND zero curvature. The results do seem to suggest NEAR flatness, but they do not yet rule out a slight positive curvature.

Plus, as Brian says, the measurements are all just concerning the portion of the cosmos which we can see. The evidence suggests that what we can see is a small sample of what there is. If we could see a larger portion it might turn out to have a different average spatial curvature from the portion scientists are now measuring. So caution is advised about jumping to conclusions.

Still, that said, your article has some quotes from DAVID J SCHLEGEL of LBNL (Lawrence Berkeley National Lab). I want to follow up on it. It may change my subjective feeling about some of these issues.

 

[marcus]

Here FWIW is the abstract of the talk David Schlegel gave at the Washington DC meeting of the AAS on 8 Jan:

456.05 – Measurements of D_A and H at z=2.4 from the SDSS-III/DR11 BOSS Lyman-alpha sample
David J. Schlegel1, Timoth\'ee Delubac2, Nicol\'as G. Busca3, James Rich2, Stephen J. Bailey1, Julian Bautista3, Andreu Front4, 1, David Kirkby5, Jean-Marc Le Goff2, Matthew Pieri6, Anze Slosar7, Eric Aubourg3, Michael Blomqvist5, Adam S. Bolton8, Arnaud Borde1, William Carithers1, Rupert A. Croft9, Kyle S. Dawson8, Daniel Eisenstein10, Jean-Christophe Hamilton3, Shirley Ho9, David W. Hogg11, Khee-Gan Lee12, Britt Lundgren13, Daniel Margala5, Jordi Miralda-Escudé14, 15, Adam D. Myers16, Pasquier Noterdaeme17, Nathalie Palanque-Delabrouille2, Isabelle Paris17, 18, Patrick Petitjean17, Nicholas Ross19, Graziano Rossi2, Matteo Viel20, 22, David H. Weinberg21, Martin White1,
23, Christophe Yeche2
1. LBNL, Berkeley, CA, United States. 2. CEA, Centre de Saclay, IRFU, Gif-sur-Yvette, France. 3. APC, Universit\'e Paris Diderot-Paris 7, Paris, France. 4. Institute of Theoretical Physics, University of Zurich, Zurich, Switzerland. 5. Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, United States. 6. Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, United Kingdom. 7. Brookhaven National Laboratory, Upton, NY, United States. 8. Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, United States. 9. Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, PA, United States. 10. Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA, United States. 11. Center for Cosmology and Particle Physics, New York University, New York, NY, United States. 12. Max-Planck-Institut f\'ur Astronomie, Heidelberg, Germany. 13. Department of Astronomy, University of Wisconsin, Madison, WI, United States. 14. Instituci\'o Catalana de Recerca i Estudis Avan\c ats, Barcelona, Spain. 15. Catalonia, Institut de Ci\`encies del Cosmos, Universitat de Barcelona/IEEC, Barcelona, Spain. 16. Department of Physics and Astronomy, University of Wyoming, Laramie, WY, United States. 17. Universit\'e Paris 6 et CNRS, Institut d'Astrophysique de Paris, Paris, France. 18. Universidad de Chile, Santiago, Chile. 19. Department of Physics, Drexel University, Philadelphia, PA, United States. 20. INAF, Osservatorio Astronomico di Trieste, Trieste, Italy. 21. Department of Astronomy, Ohio State University, Columbus, OH, United States. 22. INFN/National Institute for Nuclear Physics, Trieste, Trieste, Italy. 23. University of California, Berkeley, Berkeley, CA, United States.
Contributing teams: Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey (BOSS)
We present the most precise measures of the Baryon Acoustic Oscillation (BAO) scale at z=2.4 from the 3-dimensional clustering of the Lyman alpha forest. The Hubble parameter (BAO scale along the line of sight) is measured to 3% precision. The angular diameter distance (perpendicular to the line of sight) is measured to 5% precision. These results make use of the Sloan Digital Sky Survey III (SDSS-III) Data Release 11 (DR11), with 135 000 high-redshift quasar spectra covering 9000 square degrees. This study supersedes the previous measurements of Busca et al. (2013) and Slosar et al. (2013) with a gain
of nearly a factor of three in the amount of Lyman alpha spectra data. We also perform a detailed study of the covariance matrix of the Lyman alpha correlation, which is validated with both simulations and subsampling (data-only) techniques.

It looks quite respectable, but like a focused incremental improvement rather than a broad "breakthrough". Just my two cents, on first sight.

 

[Chronos]

Agreed, marcus! The only part is dislike is the implied temporality. I feel that approach is misguided.