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
Well yes. That's why they publish reports and continue looking for new discoveries. Otherwise we would arbitrarily decide that the universe is 13.6789023 billion years old and leave it at that, shoot disenters.
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Yes, but what YOU said was "what if there were objects 100 billion light years away that we CAN'T see" (or words to that effect).
The point being that we now have imaging capability to detect objects further away than we currently see them, and they aren't there! Which is exactly what on would expect if our estimates of the age of the Universe are correct.
If there were objects 100 billion light years away that we can't detect, it doesn't mean the Universe has to be 100 billion years old. The inflationary phase of the Big Bang inflates spacetime at superluminal speeds, and objects embedded therein are carried along for the ride (this is not a violation of Special Relativity).
Aren't they measuring the farthest white dwarf they can find to determine the age?
No.
They are looking to find the faintest (and hence coolest) white dwarf, not the most distant one. The age is determined by how much the white dwarf has cooled off. All things being equal, coolest white dwarf is the OLDEST white dwarf, and once you identify it and calculate its age, you establish a lower bound for the age of the Universe.
As I mentioned yesterday, this issue was addressed during the press conference. They stressed that the minimum detection sensitivity of their exposures was sufficiently below the level of the faintest white dwarf detected to rule out the likelyhood of there BEING fainter white dwarfs that they DIDN'T see.
But you are correct in noting that they intend to do further imaging, using the vastly more sensitive camera just installed last month on Hubble, to verify (or refute) their initial findings. And they DO intend to use more distant clusters than the one (M4) used in the current study.
If that's the case, and what we see is what we get then that would strike down the point I've been trying to make, which is that space and the particles contained in them go on and on we just don't don't see them.
Just to be clear on this point, we don't see objects beyond a certain distance (roughly 13 billion light years) because that distance corresponds to an early age of the Universe when luminous objects (stars, etc.) first formed. Anything further out would be so far back toward the beginning of the Universe that luminous objects would not have yet formed, and hence no photon's had yet been generated to find their way into our detectors that would allow us to see them.
If our estimates of the age of the Universe were too low, one would expect to continue to find more quasars as we probe out beyong 13 billion light years distance; the fact that they seem to stop at that distance is consistent with what is predicted for a roughly 14 billion year old Universe.
I knew you would....
Then the Lord spoke to Job out of the whirlwind: "Who is this that darkens my counsel / with words without knowledge? / Where were you when I laid the earth's foundation? / Tell me, if you understand. / Who marked off its dimensions? Surely you know!" (Job 38:1-5)
Seems I need to correct the overbroad use of scientific jargon by a nonscientist (i.e., me).
I completely agree that scientific research has brought about monumental changes in technology, including many items used daily by most American civilians and by the Armed Forces. However, is the best means of carrying out research through endeavors such as the topic of this thread: trying to determine the age of the universe? Such studies are drivel, in my view.
Although the thread describes a study of a study from a scientist at Canadian university, my objection generally is to forced taxpayer funding of such research here.
Absent the discipline of the free market, research pursuits can tend towards mere intellectual curiosity, rather than towards the satisfaction of tangible needs, be they military or economic. Who's more efficient: tenured professorial types, or profit-motivated entrepreneurs?
True, peripheral discoveries can result from indirect means--by looking for A, you discover method B of observing A, thus enabling the development of product C. Why not cut out the middleman and work directly towards developing product C?
Last September, many of us learned that the world was not as safe as we had thought it was--and will not be for many years to come. If we are distracted by endeavors of the mind that fail to strengthen or protect our freedom, we are weakened as a people. Our adversaries, though educationally and technologically inferior, have well-funded allies who can purchase the tools of future terror--even though they haven't the minds to discover them.
Because there is a vast universe of C out there that cannot even be imagined until we know about A. Suppose you'd asked Ben Franklin about the practical applications of his experiments into the nature of electricity? There is no possibility that he could even have scratched the surface of what we use it for now. He only wanted to satisfy his curiosity about the way the world works. It's the same thing with the quantum physics that dominates modern technology: that grew out of a bunch of guys trying to figure out how to calculate the spectral lines of the elements. Without basic research, applied research is forced to work in the incredibly narrow box of what we happen to know already. That's not good enough.
Last September, many of us learned that the world was not as safe as we had thought it was--and will not be for many years to come. If we are distracted by endeavors of the mind that fail to strengthen or protect our freedom, we are weakened as a people.
If we are distracted from our endeavors of the mind by our all-consuming preoccupation with protecting ourselves, we are weakened as a people. "It has nothing to do with defending our country, except to make it worth defending." -- E. O. Lawrence
Profit-motivated entrepreneurs are good at making money (usually.) They haven't shown much ability at making original scientific discoveries. The drug companies are pretty good at funding some research but it's very narrowly focused. One problem for privately funded research is that it tends not to be shared with others who might use it. Companies really keep things hidden. Even university researchers are not allowed to publish in some fields if privately funded.
The government has the money to sponsor more types of research, but the government isn't very good at allocating resources (too much research money is allocated for political reasons). Generally government-sponsored research is widely shared. The Europeans believe that private companies should fund development and directed research but the government should fund basic research. It's not clear how this works in practice.
One problem is that funding a $1,000,000 project is unlikely pay off. On the other hand, funding 1000 $1,000,000 projects with interproject feedback is likely to pay off the entier $1,000,000,000.
That's called "applied research" and can only be done AFTER somebody has done the pure research to discover the underlying principles that product "C" will be based upon.
As "Physicist" has already pointed out, there are vast areas that would never be delved into if all we did was applied research. Pure basic scientific research is a necessary condition for long-term applied research and development.
The trouble is that basic scientific research usually doesn't have a quick "pay-back" time. For this reason, private entrepreneurs are usually loathe to spend much money of basic pure research -- the payback time is just too long compared to applied R & D.
Personally, I do NOT support the idea of having government control the funding of scientific research. I think government ought to get out of the business of funding research, education, social programs, corporate welfare, and most other things it currently has it's fingers in. The rub is that with our tax rates where they are, few people can afford to be philanthropists and fund basic scientific research. When our taxes were much lower, this was exactly how great scientific research was funded; by rich guys who wanted their name on some big-assed telescope, for example. (most of the big telescopes at major US observatories built prior to WWII have somebody's name tacked on the front of it. The "Hooker" 100" telescope at Mt. Wilson is one example; it isn't named after a Civil War general. Some guy named "Hooker" put up a large bucket of money to help build the mirror for that telescope (the world's largest BTW, until Palomar came on line with it's 200" "Hale" telescope around 1948), and in return his name is stuck in front of it for all time.)
So, in conclusion, if we can get rid of the socialist parasites in politics, cut government spending and hence taxes to a fraction of their current levels, we can return to privately funded basic scientific research, which should make both of us happy.
The theory of a Gravastar as mentioned seems to account for two of the black hole issues, information being one of them. But, I believe it would also address the debate of whether or not the universe is contacting or expanding.
Using the published theory that the universe as we know may be inside a Gravastar lays the groundwork for my theory, “the universe is both expanding and contacting”. As “our” Gravastar moves through space and encounters matter, which it draws into itself, the pressure in the Gravastar bubble increases like the air in a balloon when compressed. This would cause our universe inside the bubble to expand for the period of time that our Gravastar was drawing in matter.
Once the Gravastar entered an area of space where matter was in lesser amount the pressure on the bubble would decrease therefore causing the matter inside (our universe) to contract or at least slow the expansion.
Thoughts anyone? B.L. of N.C.
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