Featured Research

from universities, journals, and other organizations

Dynamic, dark energy in an accelerating universe

Date:
January 14, 2013
Source:
Basque Research
Summary:
A new model is contributing towards understanding the nature of dark energy. If dark energy did not exist, the gravitational pull exerted by matter would slow down the expansion of the universe, but observations have concluded that the opposite is the case. Dark energy is what makes the universe expand in an accelerating way.

Irene Sendra-Server, PhD holder in Physics and research scientist in the UPV/EHU’s Department of Theoretical Physics and History of Science.
Credit: Image courtesy of Basque Research

The models proposed by the UPV/EHU-University of the Basque Country researcher are contributing towards understanding the nature of dark energy.

It was cosmology that drew Irene Sendra from Valencia to the Basque Country. Cosmology also gave her the chance to collaborate with one of the winners of the 2011 Nobel Prize for Physics on one of the darkest areas of the universe. And dark matter and dark energy, well-known precisely because so little is known about them, are in fact the object of the study by Sendra, a researcher in the Department of Theoretical Physics and History of Science of the UPV/EHU's Faculty of Science and Technology.

"Observations tell us that about 5% of the universe is made up of ordinary matter; 22% corresponds to dark matter, which we know exists because it interacts gravitationally with ordinary matter; another 73% is dark energy, which is known to be there because otherwise one would not be able to account for the accelerating expansion of the universe," explains Irene Sendra; "We are trying to find out a bit more about what dark energy is," she adds.

If dark energy did not exist, the gravitational pull exerted by matter would slow down the expansion of the universe, but observations have concluded that the opposite is the case.Dark energy is what makes the universe expand in an accelerating way, and contributing towards understanding its nature is the basis of the research Sendra has done as part of her PhD thesis entitled: "Cosmology in an accelerating universe: observations and phenomenology."

The research starts with the hypothesis that dark energy could be dynamic.The most widely accepted model, known as the Lambda-CDM, explains the acceleration of the universe by means of the cosmological constant, whose equation of state would have a value of -1, constant throughout the whole evolution of the universe.However, there are observations which this model cannot account for."We look for a dynamic, dark energy that would vary over time; we apply various models to the observable data, we play around with small disturbances, and we see whether they adapt better than a constant," explains Sendra.

Making use of mathematical and statistical tools, the values that the observation proposes for the parameters studied are compared with those proposed by the model."So,throughmany iterations, we can see which values would take the constants of our model.The equation of state of dark energy is worth practically -1 now, but it appears to have evolved from different values in the past; however, there is still a high percentage of error in determining these values."According to Sendra's calculations, these data are consistent with dynamic dark energy, which would vary with the redshift observed in the universe.Results that have yet to be published and obtained in collaboration with Adam Riess, the 2011 Nobel Prize Winner for Physics, go further in that direction.

In this PhD thesis, besides studying the equation of state of dark energy, a new model has been proposed and it would unite dark energy with dark matter.As Sendra explains, "They could be the same thing that is manifested in a different way depending on the context; we have explained the effect of both of them through one single component, and the observations give better results in this model than in others that try to unite matter and dark energy."

Finally, Sendra has peered at the oldest universe by means of the study of its cosmic microwave background."It is the most distant proof we have of the universe," she comments, "and the study of it tells us that the actual number of neutrinos is higher than three.Nevertheless, what we know for a fact, through the standard model of particles, is that there are three kinds of neutrinos.We have ended up with a somewhat strange value, so we are trying to account for that excess in the number of neutrinos." Sendra's proposal is heading in the direction of the string theory. According to her results, this neutrino excess could be interpreted as the contribution of primordial gravitational waves, caused by the interaction of cosmic strings at the time when the cosmic microwave background was produced.


Story Source:

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


Cite This Page:

Basque Research. "Dynamic, dark energy in an accelerating universe." ScienceDaily. ScienceDaily, 14 January 2013. <www.sciencedaily.com/releases/2013/01/130114092551.htm>.
Basque Research. (2013, January 14). Dynamic, dark energy in an accelerating universe. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2013/01/130114092551.htm
Basque Research. "Dynamic, dark energy in an accelerating universe." ScienceDaily. www.sciencedaily.com/releases/2013/01/130114092551.htm (accessed July 23, 2014).

Share This




More Space & Time News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Cargo Craft Undocks from Space Station

Raw: Cargo Craft Undocks from Space Station

AP (July 22, 2014) A Russian Soyuz cargo-carrying spacecraft undocked from the International Space Station on Monday. The craft is due to undergo about ten days of engineering tests before it burns up in the Earth's atmosphere. (July 22) Video provided by AP
Powered by NewsLook.com
NASA Ceremony Honors Moon Walker Neil Armstrong

NASA Ceremony Honors Moon Walker Neil Armstrong

AP (July 21, 2014) NASA honored one of its most famous astronauts Monday by renaming a historic building at the Kennedy Space Center in Florida. It now bears the name of Neil Armstrong, the first man to walk on the moon. (July 21) Video provided by AP
Powered by NewsLook.com
Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com
This Week @ NASA, July 18, 2014

This Week @ NASA, July 18, 2014

NASA (July 18, 2014) Apollo 11 yesterday, Next Giant Leap tomorrow, Science instruments for Europa mission, and more... Video provided by NASA
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:
from the past week

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