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
What does your mascot, Plato the Platypus, say about it?
You'll get better results if you do it after the sun goes down.
Watch it; this is a family forum.
;-)
Plato says 14.2 billion years.
Oh heck, I could do that. :-)
There are dozens of very good books on the subject, written in layman's language by the very people who are doing this research. You'd be amazed to discover how much in agreement they all are. They explain their thinking, their evidence, and how they arrive at their conclusions. Very stimulating reading. Try it.
Then I suggest you restrict yourself to logic, Mathematics, and distilled spirits, the only realms in which absolute "proof" is possible.
Scientific theories are based on consonance with observed evidence and multiple unsuccessfull attempts at falsification. Thus, they are NEVER "proven" in the sense of metaphysical certitude. That is the nature of science, and it has seerved us very well, despite it's shortcomings.
This has to be the ultimate job --predicting the age of the Universe as one of the "important" tasks of an astronomer. Sorta like the "job" of counting the angels on the head of a pin.
I remember the scientists a few years ago who "discovered" asteroids colliding with the planet Jupiter. They were dancing in the streets. Total contribution to Mankind for this crucial "discovery"? Nada. Zilch. Nothing.
If you are having trouble understanding that these two concepts are NOT mutually exclusive, I suggest you avail yourself of "Physicists" knowledge, expertise, and amazing ability to explain complex scientific concepts in a manner easily understood by layman.
He's right here on this thread. I'm sure he'd be happy to explain it to you if you were to ask him.
Does it?
They're going back 13 billion light years in time to see what happened then because that's how long it took for the light to reach us. But for all we know, as another poster said the universe goes on in infinity, there are probably galaxies a hundred trillion light years away, and farther. My point is, and it's a theory, fifteen billion years for the universe is like a second for us. It's been around a lot longer than that.
Okay; I'll bite.
Show us the contradiction you alluded to.
Does it?
the universe [has] been around a lot longer than [fifteen billion years].
Has it?
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