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
This from the same group of minds which cannot predict a major earthquake 5 minutes before it happens, even though most animals can.
I recall that post, but I don't know ... it needs some clarification. I've read that the most distant objects are receding from us at about 70% of lightspeed, judging by their redshifts. (Perhaps those estimates are higher now, it's been a while since I read that.) But let's go with 70%, which means that if you look in the opposite direction and see another such object, those two objects are separating from one another at 140% of lightspeed. So the universe is expanding faster than c, but nothing seems to be receding from us at that speed. At least that's my understanding. I'm sure that if I've got it wrong -- as I often do -- a tactful correction will appear in due course.
Is this the Clinton or Bush recession...;-) Sorry, as an economist/financial analyst, this is the only way I can contribute to this discussion...
Let's hope not...As the economist joke (applied to this situation) goes, "Assume a ball of matter with infinite mass...."
Also, the current recession was caused by deflation, not inflation. If that applies to the universe, I guess we're screwed...
Actually they are both. But my point was that a scientist of old (Pascal) trembled before the God who made the "infinite spaces" and found them terrible apart from God. For Pascal there was no contemplation of the creation apart from contemplation of the One who created.
THIS is what seems missing from so much science today: not an "it", but a "He".
Ah; so THAT'S what that smell is that permeates everything!
The Creator isn't a scientific topic, strictly speaking, as He can't be observed or tested. Pascal would have been combining science and theology, which is okay at a personal level, but it's not the way science is done.
Last time I checked, Astrophysicists and Cosmologists weren't in the business of studying earthquakes, let alone predicting them.
I could just as well ask you how many animals are able to build telescopes, rockets, and satellites.
Lastly, no one can accurately predict the weather more than a week in advance. Does that imply that scientists CAN'T measure the age of the Universe? Not for a minute. It merely is a reflection of the reality that some phenomona are dynamical and inherently sensitive to initial conditions; hence they are unpredictable beyond the short term, which has nothing to do with the article posted here.
Hmmmm...then why is it that, every so often (yearly or more, it seems), the processes yielding "similar results" change by a few billion years?
In my under 40 lifetime, the state-of-the-art guesses of the universe's age have varied by several fold.
As it is to be expected. The distance at which the recessional velocity (caused by the expansion of space-time) is equal to "c" defines the boundary of an imaginary sphere around the point of observation, within which it is possible to observe objects. Objects beyond the boundary (if they exist?) would not be observeable to someone at the center of the sphere defined above, though they would still be part of the Universe, and would be observable from points located less than the previously defined boundary distance away from such objects.
I think "Physicist" referred to this distance as the "light horizon." It defines in a very practical way the limits of the observeable Universe, from a particular point of observation.
That was probably as clear as mud....
Because the lay journalists don't bother to explain the error associated with the estimates of the age of the Universe, and because our ability to makes such measurements gets better with time.
20 years ago, the best estimate of the age of the Universe was about 10-20 billion years, or 15 +/- 5 billion. They weren't able to be more precise than that.
Today, we have a result that pegs the minimum age of the Universe at 13.7 +/- 0.5 billion years. Not only is it much more precise, it lies entirely within the range estimated 20 years ago.
In other words, the current age estimate is entirely consistent with that from 20 years ago.
I'm not getting that at all. The age of the universe is greater than the age of the luminous objects within it. So the oldest and most distant of luminous objects have had, as it were, all the time in the world to send their light to us. (The only exception I can think of would be a recently formed objects at a great distance.)
Thank you.
You may leave your gift by the door as you exit....
The time available for the photons to get here can't exceed the age of the Universe, so if an object is Age of the Universe + 10 lightyears away, assuming we have a big enough telescope, we wouldn't even be able to detect it for another ten years.
But if the distance is so far away that the recessional velocity due to the expansion of space is greater than "c", we can't see it at all. It is outside our "light horizon" or observeable Universe. And it can't see us, for exactly the same reason.
Your argument hurts your case. With weather forecasts, we can evaluate predictions against actual results, and thus gain an understanding of the limitations of meteorological sciences. The ability to observe the actual establishes the limitations of predictive technology, thus giving an objective measure of reliability.
If a particular scientific endeavor lacks predictive reliability, then it would seem an inefficient allocation of scarce educational resources and a waste of brain power. We should defund such pursuits at universities and send the $ to economically productive areas such as mechanical or electrical engineering. In fact, I'd just as soon fund wymyn's studies as quantum physics.
Because they are neither infinite nor "silent".
A better analogy is that no one can accurately measure what the weather was a week ago, or tell when the last hailstorm was, solely by looking at today's weather. Sure there are indicators which give a pretty good idea, but not to the accuracy claimed about the age & origin of the universe.
And yes I know that cosmologists don't really study earthquakes - but they DO use practically the same scientific methods and few ounces of grey matter.
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