Featured Research

from universities, journals, and other organizations

Dark Energy May Be Vacuum

Date:
January 16, 2007
Source:
University of Copenhagen
Summary:
Researchers at the University of Copenhagen's Dark Cosmology Centre at the Niels Bohr Institute have brought us one step closer to understanding what the universe is made of. The new data shows that vacuum energy is the most likely cause and the expansion history of the universe can be explained by simply adding this constant background of acceleration into the normal theory of gravity.

Researchers at the University of Copenhagen's Dark Cosmology Centre at the Niels Bohr Institute have brought us one step closer to understanding what the universe is made of. As part of the international collaboration ESSENCE they have observed distant supernovae (exploding stars), some of which emitted the light we now see more than half the age of the universe ago. Using these supernovae they have traced the expansion history of the universe with unprecedented accuracy and sharpened our knowledge of what it might be that is causing the mysterious acceleration of the expansion of the universe.

Related Articles


Background

At the end of last century astronomers discovered the startling fact that the expansion of our universe is not slowing down, as all our previous understanding of gravity had predicted. Rather the expansion is speeding up. Nothing in conventional physics can explain such a result. It means that either the universe is made up of around 70% 'dark energy' (something that has a sort of anti-gravity) or our theory of gravity is flawed.

Now, as part of the international collaboration "ESSENCE", researchers at the Danish Dark Cosmology Centre have added a new piece to the puzzle. In two papers recently released they detail observations of supernovae (exploding stars) that allow them to trace the expansion history of the universe in unprecedented detail. ESSENCE is an extension of the original team that discovered the acceleration of the universe and these results push the limits of technology and knowledge, observing light from dying stars that was emitted almost half the age of the universe ago.

In a third paper, led by the Danish team and released this week, the many new theories that have been proposed to explain the acceleration of the universe are critically assessed in the face of this new data. Dr. Jesper Sollerman and Dr. Tamara Davis lead the team who show that despite the increased sophistication in cosmological models over the last century the best model to explain the acceleration remains one that was proposed by Einstein back in 1917. Although Einstein's reasoning at the time was flawed (he proposed the modification to his theory so it could support a static universe, because in those days everyone 'knew' the universe was not expanding, it may be that he was right all along.

Scientific details

The results include 60 new type Ia supernovae discovered on the Cerro-Tololo Interamerican Observatory 4m telescope in an ongoing survey that so far has lasted four years. In order to follow up these discoveries the team uses some of the biggest telescopes in the world: the 8.2m VLT (Very Large Telescope) run by the European Southern Observatory and the 6m Magellan telescope (both in Chile), the 8m Keck telescope and the 10m Gemini telescope (both in Hawaii). The ESSENCE team includes 38 top researchers from many different countries on four continents.

The primary aim of the experiment is to measure the 'dark energy' - the thing that is causing the acceleration of the universe - to better than 10%. The feature of this dark energy that we measure is its 'equation of state'. This also allows us to check whether our theory of gravity needs modification. So far it looks like our theory is correct and that the strange acceleration of the expansion of the universe can be explained by Einstein's 'cosmological constant'.

In modern terms the cosmological constant is viewed as a quantum mechanical phenomenon called the 'energy of the vacuum'. In other words, the energy of empty space. It is this energy that is causing the universe to accelerate. The new data shows that none of the fancy new theories that have been proposed in the last decade are necessary to explain the acceleration. Rather, vacuum energy is the most likely cause and the expansion history of the universe can be explained by simply adding this constant background of acceleration into the normal theory of gravity.


Story Source:

The above story is based on materials provided by University of Copenhagen. Note: Materials may be edited for content and length.


Cite This Page:

University of Copenhagen. "Dark Energy May Be Vacuum." ScienceDaily. ScienceDaily, 16 January 2007. <www.sciencedaily.com/releases/2007/01/070116130456.htm>.
University of Copenhagen. (2007, January 16). Dark Energy May Be Vacuum. ScienceDaily. Retrieved January 30, 2015 from www.sciencedaily.com/releases/2007/01/070116130456.htm
University of Copenhagen. "Dark Energy May Be Vacuum." ScienceDaily. www.sciencedaily.com/releases/2007/01/070116130456.htm (accessed January 30, 2015).

Share This


More From ScienceDaily



More Space & Time News

Friday, January 30, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA Holds Memorial to Remember Astronauts

NASA Holds Memorial to Remember Astronauts

AP (Jan. 29, 2015) NASA is remembering 17 astronauts who were killed in the line of duty and dozens more who have died since the agency&apos;s beginning. A remembrance ceremony was held Thursday at NASA&apos;s Marshall Space Flight Center in Alabama. (Jan. 29) Video provided by AP
Powered by NewsLook.com
Asteroid's Moon Spotted During Earth Flyby

Asteroid's Moon Spotted During Earth Flyby

Rumble (Jan. 27, 2015) Scientists working with NASA&apos;s Deep Space Network antenna at Goldstone, California discovered an unexpected moon while observing asteroid 2004 BL86 during its recent flyby past Earth. Credit to &apos;NASA JPL&apos;. Video provided by Rumble
Powered by NewsLook.com
Water Fleas Prepare for Space Voyage

Water Fleas Prepare for Space Voyage

Reuters - Innovations Video Online (Jan. 26, 2015) Scientists are preparing a group of water fleas for a unique voyage into space. The aquatic crustaceans, known as Daphnia, can be used as a miniature model for biomedical research, and their reproductive and swimming behaviour will be tested for signs of stress while on board the International Space Station. Jim Drury went to meet the team. Video provided by Reuters
Powered by NewsLook.com
Mars Rover Opportunity Celebrates 11-Year Anniversary

Mars Rover Opportunity Celebrates 11-Year Anniversary

Rumble (Jan. 26, 2015) Eleven years ago NASA&apos;s Opportunity rover touched down on Mars for what was only supposed to be a 90-day mission. Since then it has traveled 25.9 miles (41.7 kilometers), further than any other off-Earth surface vehicle has ever driven. Credit to &apos;NASA&apos;. Video provided by Rumble
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins