Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dark energy existed in infant universe

20.11.2006
Using NASA's Hubble Space Telescope, researchers have discovered that dark energy, a mysterious repulsive force that makes the universe expand at an ever-faster rate, is not new but rather has been present in the universe for most of its 13-billion-year history.

A team led by Adam Riess, a professor in The Johns Hopkins University's Henry A. Rowland Department of Physics and Astronomy and a Space Telescope Institute researcher, found that dark energy was already accelerating the expansion of the universe at least as long as 9 billion years ago. This picture of dark energy would be consistent with Albert Einstein's prediction, nearly a century ago, that a repulsive form of gravity emanates from empty space.

The team will announce these findings in a media teleconference at NASA headquarters in Washington at 1 p.m. EST on Thursday, Nov. 6. (For logistics, see below.) The findings also will be published in the Feb. 10, 2007, issue of Astrophysical Journal.

"Although dark energy accounts for more than 70 percent of the energy of the universe, we know very little about it, so each clue is precious," said Riess, who in 1998 led one of the first studies to reveal the presence of dark energy. "Our latest clue is that the stuff we call dark energy was present as long as 9 billion years ago, when it was starting to make its presence felt."

Hubble's new evidence is important, because it will help astrophysicists start ruling out competing explanations that predict that the strength of dark energy changes over time, Riess said.

In addition, the researchers found that the exploding stars, or supernovae, used as markers to measure the expansion of space today look remarkably similar to those which exploded 9 billion years ago and are just now seen by Hubble. This is an important finding, say researchers, because it gives added credibility to the use of these supernovae as tools for tracking the cosmic expansion over most of the universe's lifetime.

To study the behavior of dark energy long ago, Hubble had to peer far across the universe and back into time to detect ancient supernovae, which can be used to trace the universe's expansion and determine its expansion rate at various times. The method, Riess said, is analogous to watching fireflies on a summer night. Because all fireflies glow with about the same brightness, you can judge how they are distributed throughout the backyard by their comparative apparent faintness or brightness, which depends on their distance from you.

Only Hubble can measure these supernovae because they are too distant, and therefore too faint, to be studied by the largest ground-based telescopes.

Albert Einstein first conceived of the notion of a repulsive force in space in his attempt to explain a balance the universe against the inward pull of its own gravity. If such an opposing force did not exist, he reasoned, gravity would ultimately cause the universe to implode.

But Einstein eventually rejected his own so-called "cosmological constant" idea and it remained a curious hypothesis until 1998, when Riess and the members of the High-Z Supernova Team and the Supernova Cosmology Project used ground-based telescopes and Hubble to first detect the acceleration of the expansion of space from observations of distant supernovae. Astrophysicists came to the realization that Einstein may have been right after all, that there really was a repulsive form of gravity in space. It soon after was dubbed "dark energy."

Over the past eight years, astrophysicists have been trying to uncover two of dark energy's most fundamental properties: its strength and its permanence. The new observations reveal that dark energy was present and obstructing the gravitational pull of the matter in the universe even before it began to win this cosmic "tug of war."

Hubble observations of the most distant supernovae known, reported in 2004 by Riess and colleagues, revealed that the early universe was dominated by matter whose gravity was slowing down the universe's expansion rate, like a ball rolling up a slight incline. The observations also confirmed that the expansion rate of the cosmos began speeding up about 5 billion to 6 billion years ago, like a roller coaster zooming down a track. That is when astronomers believe that dark energy's repulsive force overtook gravity's attractive grip.

The latest results are based on an analysis of the 24 most distant supernovae known, most found within the last two years.

By measuring the universe's relative size over time, astrophysicists have tracked the universe's growth spurts, much as a parent may witness the growth spurts of a child by tracking changes in height on a doorframe. Distant supernovae provide the doorframe markings read by Hubble.

"After we subtract the gravity from the known matter in the universe, we can see the dark energy pushing to get out," said the University of Western Kentucky's Lou Strolger, a supernova hunter on the Riess team.

Further observations are presently underway with Hubble by Riess and his team which should continue to offer new clues to the nature of dark energy.

Lisa DeNike | EurekAlert!
Further information:
http://www.nasa.gov/ntv
http://www.nasa.gov/newsaudio

More articles from Physics and Astronomy:

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

nachricht NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>