Posted on 04/24/2002 6:30:34 PM PDT by longshadow
By Paul Recer
AP Science Writer
Wednesday, April 24, 2002; 4:21 PM
WASHINGTON –– The universe is about 13 billion years old, slightly younger than previously believed, according to a study that measured the cooling of the embers in ancient dying stars.
Experts said the finding gives "very comparable results" to an earlier study that used a different method to conclude that the universe burst into existence with the theoretical "Big Bang" between 13 and 14 billion years ago.
Harvey B. Richer, an astronomer at the University of British Columbia, said the Hubble Space Telescope gathered images of the faintest dying stars it could find in M4, a star cluster some 7,000 light years away.
Richer said the fading stars, called white dwarfs, are actually burnt out coals of stars that were once up to eight times the size of the sun. After they exhausted their fuel, the stars collapsed into Earth-sized spheres of cooling embers that eventually will turn cold and wink out of sight.
Earlier studies had established the rate of cooling for these stars, said Richer. By looking at the very faintest and oldest white dwarfs possible, astronomers can use this cooling rate to estimate the age of the universe.
Speaking at a news conference Wednesday, Richer said the dimmest of the white dwarfs are about 12.7 billion years old, plus or minus about half a billion years.
Richer said it is estimated that star formation did not begin until about a billion years after the Big Bang. He said this means his best estimate for age of the universe is "about 13 billion years."
Three years ago, astronomers using another method estimated the age at 13 to 14 billion years. That was based on precise measurements of the rate at which galaxies are moving apart, an expansion that started with the Big Bang. They then back-calculated – like running a movie backward – to arrive at the age estimate.
"Our results are in very good agreement" with Richer's estimate, said Wendy L. Freedman, an astronomer at the Carnegie Observatories in Pasadena, Calif., and a leader of the group performing the universe age calculations three years ago.
Bruce Margon, an astronomer at the Space Telescope Science Institute, said both conclusions are based on "a lot of assumptions" but the fact that two independent methods arrived within 10 percent of the same answer is important.
"To find an independent way to measure the age and then get essentially the same answer is a fantastic advance," said Margon. It may not be the final answer for the universe's age, he said, but is "very, very, very close."
To get the new age estimate, the Hubble Space Telescope collected light from M4 for eight days over a 67-day period. Only then did the very faintest of the white dwarfs become visible.
"These are the coolest white dwarf stars that we know about in the universe," said Richer. "These stars get cooler and cooler and less luminous as they age."
He added: "We think we have seen the faintest ones. If we haven't, then we'll have to rethink" the conclusions.
The faintest of the white dwarfs are less than one-billionth the apparent brightness of the dimmest stars visible to the naked eye.
M4 is a globular cluster, thought to be the first group of stars that formed in the Milky Way galaxy, the home galaxy for the sun, early in the history of the universe. There are about 150 globular clusters in the Milky Way; M4 was selected because it is closest to Earth.
The new age estimate for the universe is the latest in a long series of attempts to measure the passage of time since the Big Bang. Edwin Hubble, the famed astronomer who first proved that the universe is uniformly expanding, estimated in 1928 that the universe was two billion years old.
Later studies, using the very expansion that Hubble discovered, arrived at an estimate of about nine billion years for the universe age. This created a paradox for astronomers because some stars were known to be more ancient and it is impossible for stellar bodies to be older than the universe where they formed.
Freedman and others then determined, using proven values for the brightness and distance of certain stars, that the universe throughout its history has not expanded at a constant rate. Instead, the separation of galaxies is actually accelerating, pushed by a poorly understood force known as "dark energy." By adding in calculations for this mysterious force, the Freedman group arrived at the estimate of 13 to 14 billion years.
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On the Net:
Hubble Images: http://oposite.stsci.edu/pubinfo/pr/2002/10
NASA: http://www.nasa.gov
If the Inflationary Cosmology is correct, and thus the geometry of Space is Euclidean (or even if Inflation is wrong, but space is still Euclidean or Hyperbolic), there should be no limit on distance between two points in the Universe. If the Universe is closed, the maximum distance is finite.
Note: this is not the same as the maximum distance we can measure another object from us.
We were discussing the age of the Universe. The methods used to determine the age of the Universe have nothing to do with the methods used to determine that age of the Earth.
And if pigs could fly (hypothetically), they'd make great pets.
Either you have evidence that the methods are erroneous, or you don't.
If you do, post them.
If you don't, why did you bring it up? It makes as much sense as my bring up flying pigs.
I don't.
Maybe it's how you worded it or how I read it, but you made it sound like that it was now pretty much a settled thing because so many of them agreed with each other.
When in fact many things that seemed settled 20 years ago..... today aren't.
New information will show up and everything will change.
I try and keep up with all this but there are still huge unsettled speculations that this is all built on.
So you can read all you want but you'll be much more ignorant when you finish than when you began.
Because you will have a better feeling for how little we really know.
And that's not a bad thing.......just a little humbling.
And your evidence for your assertion is....?
And your evidence that two different INDEPENDENT methods for estimating the age of the Universe are BOTH in error is....?
That is not acceptable. Come up with a better theory.
Burden of proof of YOUR assertion is YOURS.
Post your evidence at your leisure.
How about you, do you think it ends, or goes on forever?
Doesn't look that way. The Big Bang is unacceptable, of course, but why would it look only 13 gigayears old?
Actually, I do. You might take Physicist's and Longshadow's advice. Just because you fail to understand something does not mean that everyone else fails to.
Few, if any, scientists have claimed the universe is contracting. Hubble's measurements have been improved upon, but not refuted.
Maybe not. What if we are inside a gravastar?
Is it 18 giga-lightyears away now, or was it 18 giga-lightyears away when it exploded?
Please cite evidence for "a lot longer than thirteen billion years" from a refereed journal. Any such evidence would certainly be of interest.
This was discussed in the press conference today.
The greater the "repulsive" effect (dark energy?), the older the Universe is, relative to the age that would be acertained by the Hubble parameter alone.
The example given in the press conference was that based only on Hubble expansion observations (no repulsion/accelerating expansion effect), the age of the Universe would be about 9 billion years. When they factored in the repulsive effects on expansion, the result was about 14 billion years, which coincidentaly, is almost exactly the figure that these scientists came up with using the completely independent white dwarf cooling model methodology.
It doesn't look that way. The galaxies seem to be closer together the deeper. If you go much farther, the trend is that the galaxies will all be jammed together solid.
I apologize, I was engaging in a little hyperbole.
Just trying to make the point that an argument from consensus is flawed.
They all come to the same conclusion because they all use the same model.
But there are huge assumptions underlying the current popular model, most of which still have little support.
Thus I'll bide my time and keep a jaundiced eye on the whole endevor.
For instance the use of a globular cluster to arrive at this data point is fraught with difficulties since the age distribution of stars in globular clusters varies significantly from that of our galaxy.
We have no idea how they form.
Or even why they are where they are.
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