Humans for the most part have always believed that we are not alone, but in recent decades scientists have been more proactive in their search for alien life, and thanks to a host of discoveries, that possibility now seems more plausible than ever. But what happens once we find life beyond Earth? Scientists and scholars at a recent symposium sponsored by NASA and the Library of Congress aimed to answer that question.

The first attempt to make contact with aliens began in 1960, when astronomer Francis Drake pointed a radio telescope at two Sun-like stars located 11 light-years away, hoping to pick up a signal of intelligent life. And though his SETI experiment went unanswered, we have learned a lot in the 50 years that have passed since then.

First off, recent research shows that even life on Earth can survive in some of the most extreme environments. For example, methane-munching microbes living in rocks on the ocean floor can withstand the deep ocean's oxygen-starved environment, while life can also be found hidden a half-mile beneath Antarctica's thick ice sheet, where no sunlight has been felt for millions of years. So if organisms can withstand these conditions, what's to say they can't survive on other planets?

Scientists have also realized that liquid water - the hallmark sign for life - is not unique to our planet. Jupiter's moons Ganymede and Europa harbor large oceans beneath their icy surfaces that resemble those found on Earth. And out of Saturn's many moons, a few show exciting promise for life. Titan, its largest and by far most famous moon, boasts a mysterious sea of methane, while Enceladus is characterized by inexplicable geysers of water vapor and ice particles. What's more, just last month Nature World News reported that the moon Mimas may be added to the list of possibly habitable moons after a study hinted at a secret sea beneath its surface.

And then there is the discovery of exoplanets, with more than 1,800 alien worlds beyond our solar system identified so far, according to the symposium. In fact, there may be one trillion planets in the Milky Way alone, one-fifth (or 22 percent) of which could be Earth-like.

According to famous American astronomer Carl Sagan, "The Universe is a pretty big place. If it's just us, seems like an awful waste of space."

So scientists are on the hunt for life beyond Earth, and after 10,000 generations of humans, "ours could be the first to know," said SETI astronomer Seth Shostak.

The symposium was hosted by Steven J. Dick, the second annual Chair in Astrobiology at the Library of Congress. The video presentations can be viewed here.

Three 'Horse Races'

In a talk titled "Current Approaches to Finding Life Beyond Earth, and What Happens If We Do," Shostak talks of three possible scenarios, or "horse races," in which we could find life in the cosmos.

One likelihood is that we find it close to home, in our own solar system. NASA's Curiosity Rover at this very moment is scouring Mars for signs of past or present life. Ancient soils, for instance, with cracked surfaces and containing hollows suggest water was once present on the Red Planet.

Second, Shostak says, is that certain telescopes - like the James Webb Space Telescope to be launched in 2018 - could "sniff out" gases such as methane and oxygen located in an exoplanet's atmosphere simply by observing the reflection of light.

The last and final "horse" is that scientists could continue Drake's SETI work and keep one ear open for radio signals coming from other planets.

Regardless of how we find alien life, Shostak is confident that it will happen sooner rather than later.

"At least a half-dozen other worlds (besides Earth) that might have life are in our solar system. The chances of finding it, I think, are good, and if that happens, it'll happen in the next 20 years," he said during a hearing before the House Science and Technology Committee in May, as quoted by Discovery News.

'Time Scale Argument'

Humans are in the midst of a very technologically advanced generation, and we are making more and more progress every single day. Shostak believes scientists should take this fact into consideration while trying to make contact with other worldly beings. We are not far off, he says, from developing artificial intelligence (AI), so what's to say that other planets aren't striving to do the same, if they haven't done so already.

Known as the "time scale argument," this describes the idea that once we find extraterrestrials, they may be non-biological. Many researchers predict AI may become a reality by 2050 - about a hundred years after the invention of computers, or a hundred and fifty years after the invention of radio communication.

"The point is that, going from inventing radios to inventing thinking machines is very short-a few centuries at most," Shostak said in his lecture. "The dominant intelligence in the cosmos may well be non-biological."

It may sound far-fetched, but in a talk titled "Alien Minds," Susan Schneider, a philosophy professor at the University of Connecticut, runs with the time scale argument, or "short window observation." She explains that once we find life beyond Earth, we may be contacting "super-intelligent" beings capable of things like "mind uploading" and "immortality."

However, fellow speaker Lori Marino, a neuroscientist and current director of the Kimela Center for Animal Advocacy, is quick to point out that there is a huge gap between finding microbial life and intelligent life.

Philosophy of Life

If we do find life elsewhere halfway to the end of the century, irrespective if it's biological or not, the discovery could greatly impact us from a philosophical perspective.

Theologist Robin Lovin says: "We say in the traditions that come from the Bible that humanity is created in the image of God, or in more abstract terms we say that persons have a human dignity; that they share a status that requires us to treat all of them equally, and to treat them differently than the way we treat other life."

"Thinking about human life against that backdrop," he added, "is something different than what science is doing when it looks at human life in relation to a biological background."

So scientists striving for proof that we are not alone must also take into consideration that their findings could impact society from a philosophical and religious standpoint. This, in turn, may dictate how they handle such a discovery.

But until then, scientists continue making strides in their research, while also keeping in mind that the hunt for life is not just for bragging rights - it's also necessary for human survival.

That's why NASA has turned most of its attention to Mars in recent years.

"If this species is to survive indefinitely we need to become a multi-planet species," NASA chief Charles Bolden told attendees at the Humans to Mars Summit held in April. "We need to go to Mars, and Mars is a stepping stone to other solar systems."

Plus, learning more about the Martian planet, he adds, may tell us more about Earth's past and future, and help determine whether or not life does indeed exist beyond Earth.

"We prepare by continuing to question our assumptions about the nature of life and intelligence," conference host Dick concluded.