universe is expanding faster than we thought - NBCNews.com [fornadablog.blogspot.com]
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[fornadablog.blogspot.com], universe is expanding faster than we thought - NBCNews.com
How fast is our universe expanding? Over the decades, there have been different estimates used and heated debates over those approximations, but now data from the Spitzer Space Telescope have provided the most precise measurement yet of the Hubble constant, or the rate at which our universe is stretching apart.
The result? The universe is getting bigger a little bit faster than previously thought.
The newly refined value for the Hubble constant is 74.3 plus or minus 2.1 kilometers per second per megaparsec. The best previous estimation came from a study from the Hubble Space Telescope, at 74.2 plus or minus 3.6 kilometers per second per megaparsec. A megaparsec is roughly 3 million light-years.
To make the new measurements, Spitzer scientists looked at pulsating stars called Cepheid variable stars, taking advantage of being able to observe them in long-wavelength infrared light. In addition, the findings were combined with previously published data from NASA’s Wilkinson Microwave Anisotropy Probe. The new determination brings the uncertainty down to 3 percent, a significant advance in accuracy for cosmological measurements, scientists say.
WMAP obtained an independent measurement of dark energy, which is thought to be winning a battle against gravity, pulling the fabric of the universe apart. Research based on this acceleration garnered researchers the 2011 Nobel Prize in physics.
The Hubble constant is named after the astronomer Edwin P. Hubble, who astonished the world in the 1920s by confirming that our universe has been expanding since it exploded into being 13.7 billion years ago. In the late 1990s, astronomers discovered the expansion is accelerating, or speeding up over time. Determining the expansion rate is critical for understanding the age and size of the universe.
“This is a huge puzzle,†said the lead author of the new study, Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena. “It’s exciting that we were able to use Spitzer to tackle fundamental problems in cosmology: the precise rate at which the universe is expanding at the current time, as well as measuring the amount of dark energy in the universe from another angle.â€
Freedman led the groundbreaking Hubble Space Telescope study that earlier had measured the Hubble constant.
Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington, said the better views of Cepheids enabled Spitzer to improve on past measurements of the Hubble constant.
“These pulsating stars are vital rungs in what astronomers call the cosmic distance ladder: a set of objects with known distances that, when combined with the speeds at which the objects are moving away from us, reveal the expansion rate of the universe,†said Wahlgren.
Cepheids are crucial to the calculations because their distances from Earth can be measured readily. In 1908, Henrietta Leavitt discovered that these stars pulse at a rate directly related to their intrinsic brightness.
To visualize why this is important, imagine someone walking away from you while carrying a candle. The farther the candle traveled, the more it would dim. Its apparent brightness would reveal the distance. The same principle applies to Cepheids, standard candles in our cosmos. By measuring how bright they appear on the sky, and comparing this to their known brightness as if they were close up, astronomers can calculate their distance from Earth.
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Spitzer observed 10 Cepheids in our own Milky Way galaxy and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud. Without the cosmic dust blocking their view, the Spitzer research team was able to obtain more precise measurements of the stars’ apparent brightness, and thus their distances. These data opened the way for a new and improved estimate of our universe’s expansion rate.
“Just over a decade ago, using the words ‘precision’ and ‘cosmology’ in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two,†said Freedman. “Now we are talking about accuracies of a few percent. It is quite extraordinary.â€
“Spitzer is yet again doing science beyond what it was designed to do,†said project scientist Michael Werner at NASA’s Jet Propulsion Laboratory. Werner has worked on the mission since its early concept phase more than 30 years ago. “First, Spitzer surprised us with its pioneering ability to study exoplanet atmospheres,†said Werner, “and now, in the mission’s later years, it has become a valuable cosmology tool.â€
The study appears in the Astrophysical Journal.
Paper on arXiv: A Mid-Infrared Calibration of the Hubble Constant
Source: JPL
This report was originally published on Universe Today as "Spitzer Provides Most Precise Measurement Yet of the Universe's Expansion."
Copyright © 2012 Universe Today. Republished with permission.
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Question by ElectricMan12: What is another way to rephrase the popular saying, "You can lead a horse to water....."? What is another way to rephrase the popular saying, "You can lead a horse to water but you cannot make him drink."? Such as giving good advice. Any help would be appreciated. Best answer for What is another way to rephrase the popular saying, "You can lead a horse to water....."?:
Answer by gdwallis
It's easy to dish out advice, but seldom is it swallowed. --- You can lead a horse to water, but you can't make him walk on it. - Gary Larson You can lead a boy to college but you can't make him think. - attributed variously, George Ade, Elbert Hubbard You can lead a horticulture, but you can't make her think. - Dorothy Parker --- One who is not wise for himself cannot be well advised. - Niccolò Machiavelli Advice is least heeded when most needed. - English proverb Don't teach your grandmother to suck eggs. - proverb [to give futile advice] Don't give cherries to pigs, nor advice to fools. - Irish proverb While the discreet advise, the fool does his business. - proverb Who will not be ruled by the rudder, must be ruled by the rock. - proverb Advice to a fool goes in at one ear and out at the other. - Danish proverb If advice will not improve him, neither will the rod. - Greek proverb Giving advice to a stupid man is like giving salt to a squirrel. - Indian (Kashmiri) proverb Advice is something the wise don't need and fools won't take. - proverb He that will not be counseled cannot be helped. - Scottish proverb He who will not accept an old man's advice will someday be a beggar. - Chinese proverb --- Don't fail to give out advice. It passes time and nobody will follow it anyway. - Anon When you give honest advice, have one foot out the door. - Arnold H. Glasow Wise men don't need advice. Fools won't take it. - Benjamin Franklin --- You can't have everything. Where would you put it? - Steven Wright
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