18-June-2004, 07:24 PM
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Join Date: Jul 2003
Location: Courtenay, BC, Canada
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Scientific American Frontiers is going to have a program about Dark Matter and Dark Energy on Tuesday, June 22. Here's a link:
http://www.pbs.org/saf/1405/index.html
It's on at 8:00pm here Vancouver (we get PBS from Seattle), but you'll want to check your local listings.
This is one of my favorite shows, and it's good to see them covering this topic.
More details...
Quote:
"There's a battle going on out there that will determine the fate of the universe," says Alan Alda in "The Dark Side of the Universe," the latest episode of SCIENTIFIC AMERICAN FRONTIERS. "Itıs a battle between two great forces: one trying to pull the universe together, the other trying to push it apart."
In this episode, Alda meets scientists who are looking at the titanic struggle between Dark Matter and Dark Energy to figure out how our universe came to be and what might eventually become of it.
"The Dark Side of the Universe" airs Tuesday, June 22, 2004, 9-10 p.m. on PBS (check local listings).
How energy from the Big Bang led to the creation of our universe remains one of the great mysteries of our cosmos. Alda travels to the Las Campanas observatory in Chile, where astronomers Alan Dressler and Pat McCarthy are looking for answers.
Dressler and McCarthy are using some of the worldıs most powerful telescopes to photograph distant galaxies and record specific data about the color of the light they give off, which tells scientists how hot each individual star is. The telescopes at Las Campanas also can reveal what a star is made of and how big it is.
Dressler and his team are using this data from billions of stars to map the evolution of the universe from as far back as 7 billion years ago. They hope this reconstruction will help scientists understand how our highly diverse universe developed from a featureless, roiling cauldron of energy and matter.
In the 1970s, astronomer Vera Rubin started a scientific revolution with her discovery that stars at the edge of galaxies rotate faster than expected. Rubinıs startling revelation implied that galaxies are embedded in immense halos of invisible, or Dark, matter.
An early hypothesis was that undetected planets accounted for this unseen matter. But scientists now believe that not only is most of the missing matter probably not the stuff that stars and planets are made ofitıs probably not the stuff that anything we know is made of.
So far, the closest weıve gotten to seeing Dark Matter has been through the cameras of NASAıs WMAP spacecraft, launched in 2001. WMAP has provided the first detailed images of the oldest light in the universe, left over from the Big Bang. In the pattern of cosmic ripples left as the Big Bang cooled, WMAP scientists can see direct evidence for Dark Matterwhich may outweigh normal, visible matter by six times or more.
Astronomers believe that Dark Matter was essential to the formation of galaxies. There wasnıt enough gravity in visible matter to coalesce and make stars, so they think Dark Matter held the normal matter together and allowed it to concentrate and cool.
Though Dark Matterıs gravitational tug was indispensable to the birth of our universe, from the start itıs been opposed by an anti-gravity force that might have overwhelmed ithad conditions been right.
In the early 1990s, two groups of astronomers began examining dying stars, or supernovae, in an attempt to forecast the ultimate fate of the universe. Each team expected to find that gravity had slowed the expansion of the universe and that the universe would eventually collapse. What they found instead shocked them: not only is the universe still expanding, itıs also speeding up.
But what was speeding it up? Albert Einstein used an equational "fudge factor" to allow forif not explainthe idea of anti-gravity, later calling it his "greatest blunder." But astronomer Michael Turner was the first to name this force that could push the universe apart: Dark Energy.
Together, Dark Matter and Dark Energy rule our universe. By looking at some half dozen supernovae, ranging in age back to 11 billion years ago, astronomers at the Hubble Space Telescope have determined that the turning point in the history of the universe came about 5 billion years ago. Thatıs when Dark Matter began losing its gravitational pull against Dark Energyıs inexorable push and the universeıs expansion stopped slowing down and sped up. Now they want to know what, exactly, Dark Energy is.
Help in this search may come from a proposed new spacecraft expressly designed for supernova hunting. Able to image thousands of supernovae at a time, the SNAP satellite might not only help find out what Dark Energy is, but also help answer an even bigger question: Is there a reason why the universe maintains an almost perfect balance between the pull of Dark Matter and the push of Dark Energy? Or is the fact that Dark Energy didnıt blow the universe apart in its infancy just a lucky accident?
SCIENTIFIC AMERICAN FRONTIERS is produced by The Chedd-Angier Production Company in association with Scientific American magazine. Underwriting for the series is provided by the National Science Foundation, public television viewers and PBS. "The Dark Side of the Universe" is written, produced and directed by Graham Chedd. The series is presented on PBS by Connecticut Public Television. Visit the series on the Web at www.pbs.org/saf.
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