Featured Research

from universities, journals, and other organizations

Best time to study the cosmos was more than 13 billion years ago

Date:
May 22, 2012
Source:
Harvard-Smithsonian Center for Astrophysics
Summary:
The universe is a marvelously complex place, filled with galaxies and larger-scale structures that have evolved over its 13.7-billion-year history. Those began as small perturbations of matter that grew over time, like ripples in a pond, as the universe expanded. By observing the large-scale cosmic wrinkles now, we can learn about the initial conditions of the universe. But is now really the best time to look?

New research finds that the ideal time to study the cosmos was more than 13 billion years ago, just about 500 million years after the Big Bang - the era (shown in this artist's conception) when the first stars and galaxies began to form. Since information about the early universe is lost when the first galaxies are made, the best time to view cosmic perturbations is right when stars began to form. Modern observers can still access this nascent era from a distance by using surveys designed to detect 21-cm radio emission from hydrogen gas at those early times.
Credit: Image courtesy of Harvard-Smithsonian Center for Astrophysics

The universe is a marvelously complex place, filled with galaxies and larger-scale structures that have evolved over its 13.7-billion-year history. Those began as small perturbations of matter that grew over time, like ripples in a pond, as the universe expanded. By observing the large-scale cosmic wrinkles now, we can learn about the initial conditions of the universe. But is now really the best time to look, or would we get better information billions of years into the future -- or the past?

New calculations by Harvard theorist Avi Loeb show that the ideal time to study the cosmos was more than 13 billion years ago, just about 500 million years after the Big Bang. The farther into the future you go from that time, the more information you lose about the early universe.

"I'm glad to be a cosmologist at a cosmic time when we can still recover some of the clues about how the universe started," Loeb said.

Two competing processes define the best time to observe the cosmos. In the young universe the cosmic horizon is closer to you, so you see less. As the universe ages, you can see more of it because there's been time for light from more distant regions to travel to you. However, in the older and more evolved universe, matter has collapsed to make gravitationally bound objects. This "muddies the waters" of the cosmic pond, because you lose memory of initial conditions on small scales. The two effects counter each other -- the first grows better as the second grows worse.

Loeb asked the question: When were viewing conditions optimal? He found that the best time to study cosmic perturbations was only 500 million years after the Big Bang.

This is also the era when the first stars and galaxies began to form. The timing is not coincidental. Since information about the early universe is lost when the first galaxies are made, the best time to view cosmic perturbations is right when stars began to form.

But it's not too late. Modern observers can still access this nascent era from a distance by using surveys designed to detect 21-cm radio emission from hydrogen gas at those early times. These radio waves take more than 13 billion years to reach us, so we can still see how the universe looked early on.

"21-centimeter surveys are our best hope," said Loeb. "By observing hydrogen at large distances, we can map how matter was distributed at the early times of interest."

The accelerating universe makes the picture bleak for future cosmologists. Because the expansion of the cosmos is accelerating, galaxies are being pushed beyond our horizon. Light that leaves those distant galaxies will never reach Earth in the far future. In addition, the scale of gravitationally unbound structures is growing larger and larger. Eventually they, too, will stretch beyond our horizon. Some time between 10 and 100 times the universe's current age, cosmologists will no longer be able to observe them.

"If we want to learn about the very early universe, we'd better look now before it is too late!" Loeb said.


Story Source:

The above story is based on materials provided by Harvard-Smithsonian Center for Astrophysics. Note: Materials may be edited for content and length.


Journal Reference:

  1. Abraham Loeb. The Optimal Cosmic Epoch for Precision Cosmology. Journal of Cosmology and Astroparticle Physics, 2012 [link]

Cite This Page:

Harvard-Smithsonian Center for Astrophysics. "Best time to study the cosmos was more than 13 billion years ago." ScienceDaily. ScienceDaily, 22 May 2012. <www.sciencedaily.com/releases/2012/05/120522180624.htm>.
Harvard-Smithsonian Center for Astrophysics. (2012, May 22). Best time to study the cosmos was more than 13 billion years ago. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2012/05/120522180624.htm
Harvard-Smithsonian Center for Astrophysics. "Best time to study the cosmos was more than 13 billion years ago." ScienceDaily. www.sciencedaily.com/releases/2012/05/120522180624.htm (accessed October 2, 2014).

Share This



More Space & Time News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Astronomers Spot Largest, Brightest Solar Flare Ever

Astronomers Spot Largest, Brightest Solar Flare Ever

Newsy (Oct. 1, 2014) — The initial blast from the record-setting explosion would have appeared more than 10,000 times more powerful than any flare ever recorded. Video provided by Newsy
Powered by NewsLook.com
French Apple Fans Discover the Apple Watch

French Apple Fans Discover the Apple Watch

AFP (Sep. 30, 2014) — Apple fans in France discover the latest toy, the Apple Watch. The watch comes in two sizes and an array of interchangeable, fashionable wrist straps. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
The Water You Drink Might Be Older Than The Sun

The Water You Drink Might Be Older Than The Sun

Newsy (Sep. 27, 2014) — Researchers at the University of Michigan simulated the birth of planets and our sun to determine whether water in the solar system predates the sun. Video provided by Newsy
Powered by NewsLook.com
First Woman Cosmonaut in 17 Years Blasts Off for ISS

First Woman Cosmonaut in 17 Years Blasts Off for ISS

AFP (Sep. 26, 2014) — A Russian Soyuz spacecraft carrying an American astronaut and two Russian cosmonauts, including the first woman cosmonaut in 17 years, blasted off on schedule Friday. Duration: 00:35 Video provided by AFP
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