Dr. Jeffrey Bennett stuck to scientific protocol Nov. 30 to address the notion of extraterrestrial life at the bi-annual Sherlin Lecture on Astronomy and Space Science, sticking to what is proven vs. what is proselytized.
But it the longtime astrophysicist’s anecdotal evidence that proved most powerful in opening minds to at least the possibilities of alien life forms to the large crowd gathered at Community College of Aurora’s for the bi-annual event at the Fine Arts Forum at CentreTech.
“Every grain of sand on every beach on Earth put together, there’s as many or more stars than that with planets – very likely with Earth-like planets,” Bennett noted. “Could it really be that we’re the only grain of sand where anybody’s thinking about any of this? Yes, it could be, because we haven’t proven otherwise. But wow, it really makes you start to think.”
Bennett discussed three key areas in which Science is addressing the search for alien life and how they fit into the notion that there could be alien life elsewhere.
The Planetary context: Aliens would need possible homes. Since 2005, thanks in large part to the Keppler mission, there’s been an incredible evolution in this search for planets around other stars. Already 3,000 likely planets have been identified and is growing rapidly; at minimum, at least one-quarter of all stars have planets and are very likely 95 percent have them, Kepler data suggests.
The Biological context: Just because homes exist, doesn’t mean life can be sustained on them. Kepler mission revealed some of those planets orbiting those stars are orbiting at the right distance from their star so in principle they can have Earth-like conditions on them. And as far as we know, if it happened here, it can happen on these other planets.
The Astronomical context: In the Milky Way galaxy, there are at least 100 billion stars, probably more. There are so many stars, that it would take more than 3,200 years to even count that high, Add in the likelihood that 95 percent of those stars have planets and are in orbits in principle like Earth, “It makes the odds for life pretty good, unless we’re missing something in our picture,” Bennett said, adding, “And that’s just our galaxy. There’s also about 100 billion galaxies in the universe.”
If only one in a million of the stars in our galaxy had a civilization, that means 100,000 are possible.
And with the expectation that civilizations would be spread out over time, then 50,000 years spanned between each of those cultures. Bennett said that, given that backdrop, humans are the latest and likely dumbest of the lot from a technology standpoint and likely wouldn’t recognize their extraterrestrial counterparts.
“If aliens really are visiting us, they are so smart that as far as we’re concerned they can do magic,” he explained. “It’s not really magic, but to us, it looks like magic.”
So how does Science as it stands now on Earth find out if alien life exists?
By studying life on this orb, which has uncovered that the planet and animal kingdom are just two tiny branches of three major domains of life on Earth. Also, critically, life on Earth is mainly not like us but there’s a commonality between all these life forms: they need liquid water. So the search for extraterrestrial life starts from that jumping off point.
Several spots in our solar system have been shown to harbor liquid water in the past– Mars; Europa, Ganymede and Calisto (moons of Jupiter with a deep ocean under icy crust); and Titan and Enceladus (moons of Saturn, which boasts liquid methane). But any discoveries of life likely come at a microbial level.
Potentially discovering intelligent life is another story all together.
We’re far away from technology that can take us to the stars. At current speeds, our fastest spacecraft – 100 times faster than a speeding bullet – would take 100,000 years to get to the nearest star. Encoded messages can be sent but have not received answers form the skies. Listening for signals also has yielded nothing.
But why? There ought to be life and civilizations based on scientific fact; yet, nothing but silence.
Bennett put the likely answer into three possible categories, none scientifically proven, but each with a stunning implication attached, if true:
We are alone in the Universe: “It seems hard to very hard to believe… but it’s scientifically possible.” One commonality among virtually every religion and philosopher, Bennett said, is to become self-aware. That we are alone posits that the universe was born 14 billion years ago and it didn’t know it existed until we got here. “It’s a pretty heavy responsibility when you think about it,” he added.
Civilizations are common, but no one has colonized the galaxy: There are numerous possibilities, including the choice by extraterrestrial beings to bypass Earth or having never gotten a chance to do so because they destroyed themselves before reaching that level of technology. “This is not at all unlikely,” Bennett said. “We can easily destroy ourselves today … whether through nuclear means, terrorism … or the rapidly rising concentration of carbon dioxide in Earth’s atmosphere … We’re in territory the Earth hasn’t seen for a million years.”
There are galactic civilizations out there that have colonized and had billions of years before we got here to do it: “This is really mind-blowing. Based on our current understanding of the scientific search for extraterrestrial life, as long as we take away the ‘they all killed themselves (hypotheses)’ … we’re left with the most likely possibility being that there is already a galactic civilization and the only reason we don’t know it is there technology to us looks like magic and they haven’t chosen to tell us that they’re there yet. Which means, some time in the future, we’re going to meet them. And it’ll be like a baby meeting an adult world.”
Bennett calls the current state a turning point in history because we’re the first generation to have the power to destroy ourselves, but if not, can set our descendants on a path that eventually takes them to the stars to meet a galactic civilization that exists or start one ourselves. “That means there’s only one question left about the search for intelligent life in the universe: And that is, is there any intelligent life on Earth,” he said. “That one is the one we need to answer.”