An Older, Larger Universe

Josh Fink writes "Space.com has a very interesting article as part their weekly mystery Monday series about a new calculation that shows that the Universe is actually much older than than the 14.3 billion years old that was established in 2003. From the article, "...the universe is instead about 15.8 billion years old and about 180 billion light-years wide." The calculations were based off of a recalculation of the Hubble Constant which dictates how fast the universe is expanding, and they found it is actually 15% slower than previously thought. The findings will be printed in an upcoming edition of Astrophysical Journal."

Comments

Re:Yea, but what's outside

[Skynet]

The expansion of space isn't governed by the speed of light.

Misleading, sensational article

[StupendousMan]

This whole article is misleading. The new research has very little to do with our knowledge of the size and age of the universe.

(And, yes, I am an astronomer).

Stanek and company have used measurements of one eclipsing binary system to determine the distance to M33. This is a good way to measure distances, as it avoids the perils of even a short "ladder" of methods. They find a distance modulus of 24.92 +/- 0.12 mag to the binary. You can read their paper on astro-ph at

http://xxx.lanl.gov/abs/astro-ph?papernum=0606279

Go to Table 7 of their paper, in which they compare their distance to previous measurements. There are 12 previous values, measured by several techniques (only 2 of the papers use Cepheids). The range of those previous values is 24.32 +/- 0.45 to 24.86 +0.07/-0.11. Their new distance is inconsistent, at the 1-sigma level, with 6 of the 12 others; thus, it is consistent with 6 of the 12 others.

Yes, it's true that the HST Key Project distance to M33, computed using Cepheids, is smaller than the new distance by an amount well outside the quoted uncertainties. But that's not a big deal, by itself. M33 is only one of a number of galaxies which serves to calibrate secondary distance indicators, which may in turn be used to find the Hubble constant. A small change in the distance to M33, even if true, would not make any major change to H-nought.

Recall that M33 is close enough to us that its radial velocity is NOT caused by the expansion of the universe, but instead by the gravitational forces of the galaxies in the Local Group. The press release's statement

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.

is absolute nonsense. One cannot USE the Hubble constant and radial velocity of M33 to calculate its distance. The radial velocity of M33 is -179 km/sec, so "using" the Hubble costant to determine its distance would yield a negative distance. Phht.

This is a very nice, and very very worthwhile scientific project -- I have followed the DIRECT team's efforts for years, and encourage them to keep going! -- but the press release tries too hard to make it into some sort of breakthrough with profound immediate results.

Sigh.

Its not the size of the boat...

[ExE122]

I don't want to get flamed by saying people are asking dumb questions, but everyone just needs to stop relying on simple arithmetic when dealing with the size of space... The concepts involved are far more complicated than that.

One thing people don't seem to be grasping is that with the Big Bang model, the size of the universe isn't measured by the distance between two particles floating on the "edge". It is actually a measure of the width of the "fabric" of the known universe, space-time. Its difficult to grasp this since it is not something easily perceived.

The real reason for the size of the universe being so much larger is that the laws governing the size of space-time are not the same as the laws of spacial relativaty, and therefore are not constrained to the upper bound of the speed of light.

The best analogy that I've heard is the ant on the balloon example. The idea is that you picture an ant sitting on a balloon with a bread crumb an inch away. If you were to blow up the balloon to twice its size, the bread crumb wouldn't necessarily move to a distance of two inches from the ant.

In this example, we are the ants and we are watching the galaxies, represented by the bread crumb, moving away from us. However, the fabric of existence is expanding at a much larger rate.

The "what's beyond the edge" question is essentially a pointless question when dealing with space-time. There is no "edge" because nothing can possibly exist outside of the realm of spacetime.

And if that concept doesn't satisfy the question, then a simple-minded answer would be that an "edge" can never be reached as space-time is always expanding faster than any particle could possibly hope to keep up with it.

--
"A man is asked if he is wise or not. He replies that he is otherwise" ~Mao Zedong