Are We The Earliest Intelligent Life In The Universe?

Proxima Centauri lies in the constellation of Centaurus (The Centaur), just over four light-years from Earth. Although it looks bright through the eye of Hubble, Proxima Centauri is not visible to the naked eye.

ESA/Hubble & NASA

The study of the formation and logic of the universe — cosmology — and the study of exoplanets and their conduciveness to life do not seem to intersect much.

Scientists in one field focus on the deep physics of the cosmos, while the others search for the billions upon billions of planets out there — and seek to unlock their secrets.

But astrophysicist and cosmologist Avi Loeb, a prolific writer about the early universe from his position at the Harvard-Smithsonian Center for Astrophysics, sees the two fields of study as inherently connected and has set out to be a bridge between them. A result of his efforts is a theoretical paper that seeks to place the rise of life on Earth, and perhaps elsewhere, in cosmological terms.

His conclusion: Earth may well be a very early example of a living biosphere, having blossomed well before life might be expected on most planets. And in theoretical and cosmological terms, there are good reasons to predict that life will be increasingly common in the universe as the eons pass.

By eons, here, Loeb is thinking in terms that don’t generally get discussed in geological or even astronomical terms. The universe may be an ancient 13.7 or so billion years old, but Loeb sees a potentially brighter future for life not billions — but trillions — of years from now. Peak life in the universe, he says, may arrive several trillion years hence.

“We used the most conservative approaches to understanding the appearance of life in the universe, and our conclusion is that we are very early in the process and that it is likely to ramp up substantially in the future,” says Loeb, whose paper was published in the Journal of Cosmology and Astroparticle Physics. “Given the factors we took into account, you could say that life on Earth is on the premature side.”

This most intriguing conclusion flows from the age of the universe, the generally understood epochs when stars and then planets and galaxies formed, and then how long it would take for a planet to cool off enough to form the chemical building blocks of life and then life itself. Given these factors, Loeb says, we’re early.

In the long term, the authors determined, the dominant factor in terms of which planets might become habitable proved to be the lifetime of stars. The higher a star’s mass, the shorter its lifetime. Stars larger than about three times the sun’s mass will burn out well before any possible life has time to evolve.

Our sun is a relatively large and bright star, which is why its lifetime will be relatively short in cosmological terms (altogether, maybe 11 billion years, with 4.5 billion already gone). But smaller stars, the “red dwarf,” low-mass variety, are both far more common in the universe and also much longer lived — as in trillions of years.

These smallest stars generally have less than 10 percent the mass of our sun, but they burn their fuel (hydrogen and helium) much more slowly than a larger star. Indeed, some may glow for 10 trillion years, Loeb says, giving ample time for life to emerge on any potentially habitable planets that orbit them. What’s more, there’s every reason to believe that the population of stars in the galaxy and cosmos will increase significantly, giving life ever more opportunity to commence.

As a result, the relative probability of life grows over time. In fact, chances of life are 1,000 times higher in the distant future than now.

This calculation, however, comes with a major caveat: Scientists are sharply divided about whether a star much smaller than ours can actually support life.

The potential obstacles are many — an insufficient amount of heat and energy emanating from the star unless the planet is close in, the fact that red dwarf stars have powerful, luminous beginnings that could send a nearby planet into a runaway greenhouse condition that might result in permanent sterilization, and that many planets around red dwarfs would be close to the stars and consequently tidally locked. That means that one side of the planet would always face the star and be light, while the other would continue in eternal darkness. This was earlier considered to be a pretty sure deterrent to life.

Recent theoretical analyses of planets around these red dwarfs, however, suggests that life could indeed emerge. It could potentially survive at the margins — where day turns into night and the temperatures would likely be stable — and also in other day-side regions were temperatures could be moderated by clouds and winds. But no observations have been made to substantiate the theory.

Because of their relatively cool temperatures and resulting low brightness, individual red dwarfs are nearly impossible to see with the naked eye from Earth. But they’re out there.

The nearest star to our sun, Proxima Centauri, is a red dwarf, as are 20 of the next 30 nearest stars. Scientists announced Wednesday they had discovered that a potentially habitable planet about the size of Earth orbits Proxima Centauri. Data from the Kepler Space Telescope suggest that as many as 25 percent of red dwarfs have planets orbiting in their habitable zones — neither too hot nor too cold to keep liquid water from sometimes pooling on their surfaces.

“I think we can and we should test these theories in the years ahead with observations,” Loeb says. “We should be able to tell if nearby low-mass stars have life around them” in the decades ahead.

And if red dwarfs can support life, then the future for life in the universe is indeed grand.

The merging of cosmological theory and astronomical observation that Loeb has in mind would indeed be unusual, but it is nonetheless consistent with the interdisciplinary nature of much of the broader search for life beyond Earth. That effort has already brought together astrophysicists and geoscientists, astronomers and biologists. It’s just way too big for one discipline.

An interesting sidelight to Loeb’s argument that Earth may well be among the earliest planets where life appeared and continued is that it would provide a solution to the extraterrestrial life puzzle known as Fermi’s Paradox.

It was in 1950 that renowned physicist Enrico Fermi was talking with colleagues over lunch about the predicted existence of billions of still-to-be-discovered planets beyond our solar system, and the likelihood that many had planets around them. Fermi also was convinced that the logic of the vast numbers and of evolution made it certain that intelligent, technologically advanced life existed on some of those planets.

It was an era of fascination with aliens, flying saucers and the like, but there actually were no confirmed reports of visitations by extraterrestrial life. Ever, it seemed.

If intelligent life is common in the universe, Fermi famously wondered, “Then where is everybody?”

There are many potential answers to the question, including, of course, that we are alone in the universe. The possibility that Earth might be among the very early planets with life has not been put forward before, but Loeb says that now it has been.

“Our view is that we’re at the very beginning of life in the universe, we’re just ramping up,” he says. “So of course we haven’t been visited by anything extraterrestrial.”

As a congenital thinker in the very long term, Loeb also raises the issue of whether it makes sense for human life to remain on Earth and in our solar system. The sun, after all, will run out of fuel in those remaining 6 billion years, will expand enormously as that occurs, and then will re-emerge as a superdense white dwarf star. Any biology in our solar system would have been destroyed long before that.

But is Proxima Centauri one of those very long-lived stars?

“It will be there a very long time,” he says. “If the conditions are right, then maybe a time will come to migrate to any planets that might be around Proxima. It’s four light-years away, so it would take generations of humans to get there. Certainly very difficult, but some day in the far future people may be faced with an alternative that’s considerably worse.”


Spacecraft built from graphene could fly without any fuel

 

Graphene is a wonder material made of carbon atoms arranged in a honeycomb lattice. (Photo: Wiki Commons)

Even though it is only one atom thick, graphene is 200 times stronger than steel. It conducts heat and electricity with great efficiency, is nearly transparent, and might just be the most useful material ever discovered. The amazing properties of graphene, as well as the many inventions that have spawned from its discovery, are becoming too numerous to count. Now scientists have stumbled upon yet another incredible hallmark of this wonder material: It turns light into motion, reports New Scientist.
This latest graphene breakthrough came entirely by accident. Researchers discovered it while using a laser to cut a sponge made of crumpled sheets of graphene oxide. As the laser cut into the material, it mysteriously propelled forward. Although lasers have been shown to shove single molecules around, they shouldn’t be physically capable of moving a structure as large as the graphene sponge.
Baffled, researchers investigated further. The graphene material was put in a vacuum and again shot with a laser. Incredibly, the laser still pushed the sponge forward, and by as much as 40 centimeters. Researchers even got the graphene to move by focusing ordinary sunlight on it with a lens.
How is this possible? Researchers still aren’t sure, but there are two leading theories. One explanation is that the material is acting like a solar sail. Basically, photons can transfer momentum to an object and propel it forward, and in the vacuum of space this effect can accumulate and even generate enough thrust to move a spacecraft.
When researchers tested the solar sail theory, however, it worked too well. This led them to consider a second possibility, that the graphene is absorbing the laser’s energy, building up a charge of electrons. Eventually extra electrons are released, which act like a propellant, pushing the graphene material in the opposite direction.
Though this second theory is a bit vague and incomplete, scientists were able to detect a current flowing away from the graphene as it was exposed to a laser, suggesting that the theory is at least on the right track.
So what does this all mean? It means that researchers may have just accidentally discovered a propulsion system for a spacecraft that requires no fuel whatsoever. Essentially, a spacecraft built from graphene could explore the heavens powered by nothing more than sunlight.
“While the propulsion force is still smaller than conventional chemical rockets, it is already several orders larger than that from light pressure,” wrote researcher Yongsheng Chen and colleagues of the discovery.
More study is required before researchers can say for sure if the material can offer a viable alternative to fuel propulsion, but the results so far are exciting. Truly, there seems to be no end to the amazing qualities of graphene.

By: Bryan Nelson

 

 

NASA Is Seriously Revving Up The Search For Alien Life

  • NASA Is Seriously Revving Up The Search For Alien Life

A few weeks ago, NASA chief scientist Ellen Stofan made news by saying, “I think we’re going to have strong indications of life beyond Earth within a decade, and I think we’re going to have definitive evidence within 20 to 30 years.” It was a bold statement, but NASA is now backing those words with action.

The field of astrobiology just got a significant boost thanks an ambitious new alien-hunting initiative launched by NASA. Called NExSS, the initiative will bring together an impressive array of experts and teams across a variety of scientific fields.

The goal of NExSS — short for Nexus for Exoplanet System Science — is to improve our understanding of extrasolar planets, and how their stars and neighboring planets interact to support life. To achieve this, NASA has put together a multidisciplinary team consisting of earth scientists, planetary scientists, heliophysicists, and astrophysicists.

“This interdisciplinary endeavor connects top research teams and provides a synthesized approach in the search for planets with the greatest potential for signs of life,” noted Jim Green, NASA’s Director of Planetary science, in a statement. “The hunt for exoplanets is not only a priority for astronomers, it’s of keen interest to planetary and climate scientists as well.”

Since 1995, over 1,000 exoplanets have been discovered. Thousands of additional candidates are still waiting to be confirmed. The time has come, says NASA, for scientists to acquire a better understanding of these distant objects to learn how they might be capable of giving rise to life and how we might be able to detect their bio signatures from Earth using current and next-gen telescopic technologies.

By applying a “system science” approach, the teams will work to understand how biology interacts with the atmosphere, geology, oceans, and interior of a planet, and how host stars contribute to habitability. At the same time, the scientists will classify the diversity of worlds (including a “periodic table of planets”), assess potential habitability of exoplanets, and develop new alien-hunting tools and technologies.

Among the teams assembled, some notable contributions will come from: the University of Arizona, Tucson’s “Earth in Other Solar Systems” team; Hampton University, Virginia’s “Living, Breathing Planet” team; NASA’s own Solar System astrobiological initiative; and the Pennsylvania State University project studying the atmospheres of giant planets orbiting hot Jupiters.

This is very exciting stuff, especially in consideration of future projects such as the James Webb Space Telescope (JWST), the Transiting Exoplanet Survey Satellite (TESS), and the Wide-field Infrared Survey Telescope (WFIRST). Over the course of the next 10-to-20 years, astrobiologists may very well detect signs of alien life. But that alien life is bound to be microbial in nature. The search for extraterrestrial intelligence is another challenge altogether.

Image: NASA.