Universe Might be Bigger and Older than Expected

[darkangel199]

thought this was interesting:

 

A project aiming to create an easier way to measure cosmic distances has instead turned up surprising evidence that our large and ancient universe might be even bigger and older than previously thought.

 

If accurate, the finding would be difficult to mesh with current thinking about how the universe evolved, one scientist said.

 

A research team led by Alceste Bonanos at the Carnegie Institution of Washington has found that the Triangulum Galaxy, also known as M33, is about 15 percent farther away from our own Milky Way than previously calculated.

 

The finding, which will be detailed in an upcoming issue of Astrophysical Journal, suggests that the Hubble constant, a number that measures the expansion rate and age of the universe, is actually 15 percent smaller than other studies have found.

 

Currently, most astronomers agree that the value of the Hubble constant is about 71 kilometers per second per megaparsec (a megaparsec is 3.2 million light-years). If this value were smaller by 15 percent, then the universe would be older and bigger by this amount as well.

 

Scientists now estimate the universe to be about 13.7 billion years old (a figure that has seemed firm since 2003, based on measurements of radiation leftover from the Big Bang) and about 156 billion light-years wide.

 

The new finding implies that the universe is instead about 15.8 billion years old and about 180 billion light-years wide.

 

A new way to measure distance

 

The researchers reached their surprising conclusion after using a new method they invented to calculate intergalactic distances, one that they say is more precise and requires fewer steps than standard techniques.

 

"We wanted an independent measure of distance—a single step that will one day help with measuring dark energy and other things," said study team member Krzysztof Stanek from Ohio State University.

 

The new method took 10 years to develop and relied on optical and infrared measurements gathered from telescopes all around the world. The researchers looked at a binary star system in M33 where the stars eclipsed each other every five days. Unlike single stars, the masses of paired stars can be precisely calculated based on their movements. With knowledge of the stars' masses, the researchers could calculate their true luminosities, or how bright they would appear if they were nearby.

 

The difference between the true luminosity and the observed luminosity gives the distance between the stars and Earth. The team's results suggested that the stars were about 3 million light-years from Earth—or about half-a-million light-years farther than would be expected using the commonly accepted Hubble constant value.

 

'Not impossible'

 

Lawrence Krauss, a professor of astronomy and chair of the Department of Physics at Case Western Reserve who was not involved in the study, said the idea of a significantly reduced Hubble constant would be hard to accommodate.

 

"Things fit right now very well for a Hubble constant of a low 70s," Krauss said in a telephone interview. "It corresponds very well with the age of globular clusters as we've determined them and the age of the universe. It would be hard, although not impossible, to change things by 15 percent."

 

Stanek said his team plan to follow up their finding with distance measurements for either another binary star system in M33 or to look for a binary system in another galaxy, perhaps Andromeda.

 

"It's extremely important to have independent measurements of the Hubble constant," Stanek told SPACE.com. "That's what we're working towards."

 

http://www.space.com/scienceastronomy/060807_mm_huble_revise.html

[Locrian]

Apoligies if I'm going to sound like an Eeyore here, but I think the author of this article does not have things in perspective.

 

1) 16 billion and 14 billion are pretty close. It was only a decade ago that estimates ranged form 8 billion to 20+ billion.

 

2) Their method of determining Hubble's constant has some room for error. They determine the masses exactly, but deducing the absolute value of the brightness based on the mass is not exact.

 

3) The scientists, as far as I can tell, have a sample size of one.

 

I really think the journalist involved here didn't look critically enough at the information they were given. It does not seem to be newsworthy to me at this time.

 

Thanks for posting it anyways though.

[KaiduOrkhon]

"The Mt. Wilson astronomer, Carl Sandage, found that stars in a cluster called NGC 188 appeared to be at least 24 billion years old. 'We are in trouble', said Sandage... for the earth could certainly be younger than the universe, but if the universe has been expanding at the present rate for 24 billion years, it would seem that it should be more spread out than it is. So the astronomers have a new problem to resolve." - Isaac Asimov, THE INTELLIGENT PERSON'S GUIDE TO SCIENCE, p. 49-50

 

Asimov states in the same discussion on the only recently discovered 'expanding universe':

 

"Astronomers have now generally accepted the fact of this expansion, and Einstein's 'field equations' of his General Theory of Relativity can be construed to fit an expanding universe." - Isaac Asimov, THE INTELLIGENT PERSON'S GUIDE TO SCIENCE, p. 49

[Martin]

I really think the journalist involved here didn't look critically enough at the information they were given. It does not seem to be newsworthy to me at this time.

.

 

Yes thanks for posting this, darkangel (I see your handle rhymes with "archangel":-) )

 

Locrian I share your reservations about the newsworth!

 

the figure of 156 billion LY was merely a LOWER BOUND published in 2004

http://www.space.com/scienceastronomy/mystery_monday_040524.html

It was in connection with a paper by Neil Cornish and David Spergel et al.

They were NOT suggesting that the U is only that big, or even that it is finite.

According to them it could just as well be 156 TRILLION as 156 billion.

A lower bound is only, so to speak, HALF an estimate of the size of something.

So it is misleading to suggest that there's an estimate of the size of the universe which just increased by 15 or so percent.

 

what would be significant is if there were more measurements like this and they led to a REVISION OF THE HUBBLE PARAMETER.

that might happen but would take years.

 

=====

so what is in this news item for us?

 

Well in the past the distance scale has been based on looking at eclipsing binaries (DEB detached ecl. bin. pairs of stars) in the LARGE MAGELLANIC CLOUD and once we know how far away the LMC is, then we can calibrate our CEPHEIDS!

 

and then we can go observe cepheids in other galaxies, in the time honored manner.

 

Locrian please correct me if any of this is wrong. what I want to say is THIS IS THE FIRST DEB anyone has ranged IN ANOTHER GALAXY FARTHER AWAY THAN LMC.

 

so it is definitely an important step forward! M33(triangulum) and M31(andromeda) are quite a lot farther away than LMC, and they are much bigger and have more Cepheids.

 

So it would be a big improvement if people could get the range on a dozen or so DEBs in places like M33 and M31.

 

As the article says, Bonanos (Carnegie Inst., DC) is the team leader. When the Ohio State guy refers to "my team" he apparently means "the team of which I am a member".

 

FOR MORE DETAILS, THE SCHOLARLY ARTICLE by Bonanos et al that this news report is based on is

http://arxiv.org/abs/astro-ph/0606279

The First DIRECT Distance Determination to a Detached Eclipsing Binary in M33

 

A. Z. Bonanos, K. Z. Stanek, R. P. Kudritzki, L.M. Macri, D. D. Sasselov, J. Kaluzny, P. B. Stetson, D. Bersier, F. Bresolin, T. Matheson, B.J. Mochejska, N. Przybilla, A.H. Szentgyorgyi, J. Tonry, G. Torres

36 pages, 12 figures, accepted for publication in ApJ

 

"We present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. ....

 

It contains two O7 main sequence stars with masses of 33.4+/-3.5 Mo and 30.0+/-3.3 Mo and radii of 12.3+/-0.4 Ro and 8.8+/-0.3 Ro, respectively. We derive temperatures of 37000+/-1500 K and 35600+/-1500 K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92+/-0.12 mag (964+/-54 kpc), which is ~0.3 mag longer than the Key Project distance to M33...."

 

the astrom. distance scale is interesting, how it is constructed. here is a bit on that

http://en.wikipedia.org/wiki/Astronomical_distance

http://cassfos02.ucsd.edu/public/tutorial/Distances.html

 

see especially method J in Ned Wright's list of distance methods

http://www.astro.ucla.edu/~wright/distance.htm

[KaiduOrkhon]

On and off topic in accordance with Martin's address to darkangel.

To point out that with an apostrophe d'archangel means 'of the arch angel'.

[Locrian]

so it is definitely an important step forward! M33(triangulum) and M31(andromeda) are quite a lot farther away than LMC' date=' and they are much bigger and have more Cepheids.

 

So it would be a big improvement if people could get the range on a dozen or so DEBs in places like M33 and M31.[/quote']

 

You are absolutely right! Having a second anchor galaxy would be an achievement. This is clearly stated in the paper, which I just finished reading. I still have that bad feeling in my stomach, due to the sample size. I hope it takes them less than ten years to add more observations to it.

[Sayonara]

I think the author of this article does not have things in perspective.

Congratulations are in order for this cosmic pun

[Martin]

Locrian (and others) this might interest you.

Ned Wright has a fascinating short discussion of this result at his website.

for various reasons the original report OVERSTATED the affect on the estimated age of the universe. And (see what he says) may have misinterpreted the affect on size estimates altogether---in a sense gotten it backwards:-)

 

Here is what he says

(for the link just google Ned Wright and look in his "news of the universe" on the front page)

 

===quote Ned Wright===

 

An Older but Larger Universe?

 

 

Ohio State astronomers have measured a new precise distance to the nearby galaxy M33 based on a spectroscopic eclipsing binary. Their value is 15% larger than the old Cepheid based distance. By itself this says nothing about the Hubble constant because M33 is so close to the Milky Way that its radial velocity is dominated by random motions, not the expansion of the Universe. But it could indicate that Cepheid distances are incorrect by 15%.

 

If so, the Hubble constant would be smaller: about 62 instead of 72 km/sec/Mpc. But the claim in the OSU press release that "the universe could be [...] 15 percent older" is incorrect. If the Hubble constant is lower, then CMB anisotropy data require that OmegaM, the ratio of the matter density to the critical density, be higher, so the vacuum energy is lower, and the change in the age of the universe is considerably smaller, as shown in graph at right [click on the graph to enlarge] which shows the age vs. Ho for CMB consistent models as the solid curve, and the 1/Ho behavior assumed by the OSU press release as the dashed curve. So the Universe would not be 15% older but perhaps 7% older.

 

The claim that the Universe would be 15% larger is partially incorrect. Even though relatively nearby galaxies would be 15% further away the actual size of the Universe would go from infinite (flat) to finite (closed) but very big, which is a smaller Universe. The distance to distant quasars at redshift z=6 would increase by only 4%, and the distance to the last scattering surface changes less than 0.5% because this is what is fixed by the CMB.

 

CNN quoting space.com and John Johnson of the LA Times accepted the press release's claims of a 15% older and larger Universe uncritically. The real news is that a new method for precision distance measurements has achieved its first result. It will be averaged in with other methods used to calibrate the Cepheid period-luminosity relation and lead to a few percent decrease in the Hubble constant.

 

One of the methods to be averaged will be the Sunyaev-Zeldovich effect which gives Ho = 77 +/- 10 km/sec/Mpc according to a recent paper. This agrees with the values of Ho from WMAP and HST quite well

=== endquote===