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
A bottle of Scotch 20 years older??????
;-\
This will still not tell us how the universe got here. It may help in the investigation, but it will not tell us the important question of, where did it come from?
Pascal trembled at the immensity of the universe and saw no point apart from God. Modern scientists can guess all they want (and who can disprove their claims...after all, no one who existed x-billion years ago is here to disprove them).
The next thing I want to hear from a scientist is that, after having seen the immensity of the universe, they fell on their faces before the Living God who WAS there whenever earth was created.
I's possible, yes. But two preconditions would have to be met: (1) such galaxies would have had to exist 100 billion years ago; because (2) the universe would have to be at least 100 billion years old, so that the light from such galaxies would have had time to get to us.
I don't. Assuming the error estimates were done honestly, they will not all overlap. Statistically, we would expect approximately 2/3 of all measurements to include the correct value, and 1/3 of the measurements not to. Do a weighted average of the independent numbers, and then do a chi-squared. You might find that the agreement between them is suspiciously good.
Uh, you do understand the difference between a measurement and a theory, don't you?
I don't think that's the case, I think space is eternity. But anything's possible, which is why I'm skeptical of claims like the ones being made in this article. There's too much to know yet before drawing these sorts of conclusions.
The universe does bend, but unlike a road, the light bends along with it.
If the universe stops where the last stars we see about 13+ billion light years away, then we must be contained in something would you agree, similar to the gravastar theory?
The universe does not have a boundary. If you think in two dimensions, for a moment, it could be akin to the surface of the Earth: there could be a finite amount of space, but you could travel infinitely in any direction, if you wanted to.
I don't think that's the case, I think space is eternity.
Space may or may not be infinite, but in the first place, the amount of "stuff" we can in principle travel to (which is what I mean when I talk about the "universe") is demonstrably finite, and the "stuff" we can see is of finite age. Look out into the universe, and you see that it was a very different place 10 billion years ago.
But anything's possible,
That's just it. Some things are possible, but not just anything. At its core, the universe behaves according to one set of universal laws. Even in the complete absence of theory, our measurements have constrained pretty severely what those laws might be. We don't know nothing.
Don't be fooled by the overblown rhetoric of a journalist. Physicists are always waiting expectantly for the latest violation of muon g-2. If you read the FR discussions here and here, you'll find my explanations of the significance of muon g-2 violation, and why we expect such violations to appear.
The muon g-2 result hardly turns physics on its head. We've always known that the standard model of particle physics is incomplete. What the measurement does is pare down the myriad extensions to the standard model that are floating around out there. At most one of those theories is correct. In any case, is highly unlikely that the correct model will overthrow much of what we already believe we know about particle physics.
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