New insights on dark energy

New insights on dark energy
A representation of the evolution of the universe over 13.8 billion years. Different methods of studying cosmic expansion yield slightly different results, including for the age of the universe. Astronomers have calculated that these discrepancies could be reconciled if the dark energy that drives cosmic acceleration were not constant in time. Credit: NASA and the WMAP consortium

The universe is not only expanding - it is accelerating outward, driven by what is commonly referred to as "dark energy." The term is a poetic analogy to label for dark matter, the mysterious material that dominates the matter in the universe and that really is dark because it does not radiate light (it reveals itself via its gravitational influence on galaxies). Two explanations are commonly advanced to explain dark energy. The first, as Einstein once speculated, is that gravity itself causes objects to repel one another when they are far enough apart (he added this "cosmological constant" term to his equations). The second explanation hypothesizes (based on our current understanding of elementary particle physics) that the vacuum has properties that provide energy to the cosmos for expansion.

For several decades cosmologies have successfully used a relativistic equation with and to explain increasingly precise observations about the cosmic microwave background, the cosmological distribution of galaxies, and other large-scale cosmic features. But as the observations have improved, some apparent discrepancies have emerged. One of the most notable is the age of the universe: there is an almost 10% difference between measurements inferred from the Planck satellite data and those from so-called Baryon Acoustic Oscillation experiments. The former relies on far-infrared and submillimeter measurements of the and the latter on spatial distribution of visible galaxies.

CfA astronomer Daniel Eisenstein was a member of a large consortium of scientists who suggest that most of the difference between these two methods, which sample different components of the cosmic fabric, could be reconciled if the dark energy were not constant in time. The scientists apply sophisticated statistical techniques to the relevant cosmological datasets and conclude that if the dark term varied slightly as the universe expanded (though still subject to other constraints), it could explain the discrepancy. Direct evidence for such a variation would be a dramatic breakthrough, but so far has not been obtained. One of the team's major new experiments, the Dark Energy Spectroscopic Instrument (DESI) Survey, could settle the matter. It will map over twenty-five million galaxies in the , reaching back to objects only a few billion years after the big bang, and should be completed sometime in the mid 2020's.


Explore further

New supernova analysis reframes dark energy debate

More information: Gong-Bo Zhao et al. Dynamical dark energy in light of the latest observations, Nature Astronomy (2017). DOI: 10.1038/s41550-017-0216-z
Journal information: Nature Astronomy

Citation: New insights on dark energy (2017, October 2) retrieved 15 October 2019 from https://phys.org/news/2017-10-insights-dark-energy.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
2175 shares

Feedback to editors

User comments

Oct 02, 2017
Or it could be a simple answer

https://sites.goo.../home/h2

Oct 02, 2017
"The universe is not only expanding - it is accelerating outward" from article

"The readings of the ever increasing red shift with the increase of distance between galaxies can support that. If "the most distant objects in the universe are the galaxies GN-z11 13,39 bn ly ..." are also the fastest objects, then, according to Big Bang, these galaxies are also the oldest ones.
The relation is obvious: the greatest speed is related to the oldest and most distant objects.
How can, then, Hubble's law be valid? How can universe be spreading with the increasing speed, if that applies only for the oldest and most distant galaxies?" https://www.acade...eory.doc

Oct 03, 2017
Ok so the redshift theory does not match scientific observation mmm try this
http://www.newton...dex.html

Oct 03, 2017
And take a look at this non doppler redshift
http://www.newton...dex.html

Oct 03, 2017
A varying cosmological constant is one possibility. There are others.

Oct 03, 2017
This comment has been removed by a moderator.

Oct 03, 2017
Nikola the universe is not expanding into anything. The universe is ALL the space that exist and it's content , by definition. So if there is something to expand into, that something is also part of the universe.

Oct 04, 2017
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more