"(scientificamerican.com 10/04/2012) The newest measurements, courtesy of NASA's Spitzer Space Telescope, come from infrared observations of distant variable stars.

The universe just got a new speeding ticket.

The most precise measurement ever made of the speed of the universe's expansion is in, thanks to NASA's Spitzer Space Telescope, and it's a doozy. Space itself is pulling apart at the seams, expanding at a rate of 74.3 plus or minus 2.1 kilometers (46.2 plus or minus 1.3 miles) per second per megaparsec (a megaparsec is roughly 3 million light-years).

If those numbers are a little too much to contemplate, rest assured that's really, really fast. And it's getting faster all the time.

American astronomer Edwin P. Hubble first discovered that our universe isn't static in the 1920s. In fact, Hubble found, space has been expanding since it began with the Big Bang 13.7 billion years ago. Then, in the 1990s, astronomers shocked the world again with the revelation that this expansion is speeding up (this discovery won its finders the 2011 Nobel Prize in physics).

Ever since Hubble's initial discovery, scientists have been trying to refine their measurement of the universe's expansion rate, called the Hubble Constant. It's a hard measurement to make.

The new value reduces the uncertainty in the Hubble Constant to just 3 percent, and improves the precision of the measurement by a factor of three compared to a previous estimate from the Hubble Space Telescope.

"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," Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena, Calif., said in a statement. "Now we are talking about accuracies of a few percent. It is quite extraordinary."

The new measurement doesn't just tell scientists how fast the universe is expanding, but helps shed light on the mystery of why this expansion is accelerating. Dark energy is the name given to whatever is causing the universe's expansion to speed up. Yet scientists have little idea what it is..."

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