Featured Research

from universities, journals, and other organizations

We Are Not Alone - Or Are We?

Date:
January 26, 2000
Source:
University Of Washington
Summary:
A new book by two University of Washington scientists contends that, contrary to popular thought, we just might be alone and Earth might be unique, if not in the universe at least in this celestial neighborhood.

The annals of science fiction are filled with advanced extraterrestrial creatures like Klingons and Wookies, Vogons and Romulans, all carrying on in a human sort of way. And while screenwriters and novelists weave stories around these characters, some people scour the heavens for signs that such highly evolved beings really are out there.

Related Articles


But a new book by two University of Washington scientists contends that, contrary to popular thought, we just might be alone and Earth might be unique, if not in the universe at least in this celestial neighborhood.

In "Rare Earth," published this month by Copernicus Books/Springer, paleontologist Peter Ward and astronomer Donald Brownlee examine the remarkable confluence of conditions and events that deposited life-forming chemicals on Earth, allowed simple life to gain a foothold and then protected the planet sufficiently and created just the right environmental factors for advanced life to slowly evolve.

"It seems like something a lot of people don't want to hear, yet nearly everyone who works in these areas has remarked at one time or another how unusual the Earth is," said Brownlee, an expert on comets, the space bodies that might have delivered the first organic chemicals and life-sustaining water to Earth.

In fact, he and Ward, whose extensive research on the fossil record has provided key insights into prehistoric mass extinctions, frequently discuss the Earth's unusual character with students in their astronomy and geological sciences classes.

The scientists don't argue that life is rare. In fact, recent evidence showing simple microbial life can survive extreme conditions on Earth is an indicator that such life also might be widespread in the galaxy and the universe.

"But you need to have a vast amount of time to let evolution ramp up to animals, and we think there are only a small number of planets where that could happen," said Ward.

The key, he said, is having near equilibrium in such things as temperature and water content over enormous time spans.

Microbes have shown they can live in some of the harshest Earth environments imaginable, while advanced plant and animal life requires a delicate balance of conditions.

"For 90 percent of the age of this planet, life was slime at the bottom of the ocean," Brownlee said. But that life was given a one-in-a-million opportunity to gradually evolve to the complexity it enjoys today.

"The underlying theme of the book is that the Earth is a very charmed planet," he said. "We know of no other body that is even remotely like Earth."

Factors that made advanced life possible include the Earth's having:

* The proper distance from the sun to allow development of habitat for complex life and ensure that water remains liquid, not vapor or ice.

* The proper mass to retain atmosphere and ocean.

* Plate tectonics, which act as a sort of atmospheric thermostat, build land masses and enhance biotic diversity.

* A neighbor the size of Jupiter, not too close and not too far away, that can use its gravity to protect the planet from too many life-extinguishing collisions with comets and asteroids.

* A stable orbit unperturbed by giant planets.

* A large moon at the right distance to stabilize tilt, thus ensuring seasonal climate fluctuations that are not too severe.

* Enough carbon to support development of life but not so much to allow for runaway greenhouse conditions.

In addition, Brownlee and Ward contend, the solar system's position in the Milky Way galaxy also is key to life development on Earth. At the edge of the galaxy, many stars are too metal-poor for planet formation, while the center of the galaxy has extreme energy processes that would hinder complex life.

The "charmed" conditions on Earth won't always be present. Someday, some way, evolution on Earth will end. That could be when the sun gets so hot that life can no longer survive, when ultimately the ocean boils and surface rocks melt.

"There will be a time when there will be no record of life ever having existed on Earth," Brownlee said.

He and Ward acknowledge that their assumptions about how uncommon advanced life might be in the universe are based on observed conditions that allowed evolution on Earth. But this is the only place in which advanced life is known to have occurred, and it is one of only a handful of places in the solar system where even microbial life is suspected, making this planet the ultimate laboratory on advanced life.

A key condition for life on Earth is the presence of carbon, because of its unique properties.

"Probably all life is based on carbon," Brownlee said. While he concedes the possibility that life has evolved elsewhere based on an element such as silicon, he remains skeptical of that theory.

"Many things are possible. You can never imagine everything the universe can do. But we know it didn't happen here," Brownlee said. "If things have to obey physical and chemical laws, then there really aren't a lot of options in nature."


Story Source:

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


Cite This Page:

University Of Washington. "We Are Not Alone - Or Are We?." ScienceDaily. ScienceDaily, 26 January 2000. <www.sciencedaily.com/releases/2000/01/000126080531.htm>.
University Of Washington. (2000, January 26). We Are Not Alone - Or Are We?. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2000/01/000126080531.htm
University Of Washington. "We Are Not Alone - Or Are We?." ScienceDaily. www.sciencedaily.com/releases/2000/01/000126080531.htm (accessed October 24, 2014).

Share This



More Fossils & Ruins News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Fossil Treasures at Risk in Morocco Desert Town

Fossil Treasures at Risk in Morocco Desert Town

AFP (Oct. 23, 2014) Hundreds of archeological jewels in and around the town of 30,000 people prompt geologists and archeologists to call the Erfoud area "the largest open air fossil museum in the world". Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Newsy (Oct. 23, 2014) A 45,000-year-old thighbone is showing when humans and neanderthals may have first interbred and revealing details about our origins. Video provided by Newsy
Powered by NewsLook.com
Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Newsy (Oct. 23, 2014) You've probably seen some weird-looking dinosaurs, but have you ever seen one this weird? It's worth a look. Video provided by Newsy
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


Plants & Animals

Earth & Climate

Fossils & Ruins

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