Dark Energy Really IS Real

Posted by Heartmind _Featured_, Science Friday, September 21st, 2012

Jennifer Ouellette
Discovery News

Our universe is a mysterious place. Only 4 percent or so is made up of the ordinary matter we see around us, including all those galaxies filled with stars. The rest, physicists believe, is made of up weakly interacting dark matter, and a mysterious substance called dark energy that is causing the cosmos to expand at an accelerating rate.

At least, that’s the working hypothesis, and it seems to fit the data, although there are scientists who question its existence and tout alternatives to explain that accelerating expansion.

A new, two-year study by scientists at the University of Portsmouth and Ludwig-Maximilians-Universitat Munchen concludes that dark energy does, indeed, exist. Those results just appeared in the journal Monthly Notices of the Royal Astronomical Society.

In the early 20th century, scientists believed the universe was in a steady state. But when Albert Einstein was working on his theory of general relativity, the math just didn’t add up: the universe should have been expanding. So he invented something called the cosmological constant — a mathematical trick to balance everything out so that the equations described a static universe, rather than an expanding one.

But then astronomer Edwin Hubble discovered the universe actually was expanding — Einstein’s original equations were correct. He dubbed the cosmological constant (lambda) his “greatest blunder.”

The universe wasn’t done surprising us, however. In 1998, astronomers studying distant exploding stars called a Type 1A supernovae discovered that not only was the universe expanding, but that the rate of expansion was accelerating due to some type of unknown force or dark energy. And one of the explanations for this effect is — you guessed it — Einstein’s cosmological constant.

While that discovery snagged its team leaders the 2011 Nobel Prize in Physics, it’s not the only evidence in favor of dark energy. For instance, last May, a team of scientists from Melbourne’s Swinburne University announced their independent confirmation of both the existence of dark energy and its rate of expansion, based on four years of data collected by a powerful spectrograph at the Australian Astronomical Observatory.