alien life

Were There Alien Civilizations?

This is not a new question in the world, or even this show. 55 years ago astronomer Frank Drake came up with an equation that weighed the odds for aliens. This is equation is something we explore in episode 022. But what's happened in-between now and then? Now two astronomers have tweaked the formula to come up with a slightly different spin. NASA’s planet-hunting Kepler space telescope is helping, too. link

Woody Sullivan (University of Washington) and Adam Frank )University of Rochester) published their complicated findings recently in the May 2016 issue of Astrobiology. They slightly alter the question - not if they exist, but if they did. They say:

“While we do not know if any advanced extraterrestrial civilizations currently exist in our galaxy, we now have enough information that they almost certainly existed at some point in cosmic history,” (Adam Frank)

According to them, there’s an astronomically high chance that other technological civilizations have risen and fallen elsewhere in the universe at some point in its 13.8 billion-year history.

How did they arrive at this conclusion? Well, by deconstructing the Drake equation. Here's how they use the equation:

  • They start out with an estimate of 20 sextillion stars in the observable universe (2 x 1022).
  • There appears to be at least one planet for every star (1.0).
  • And about one-fifth of those planets appear to orbit in habitable zones (0.2).

That gives you an estimate of habitable planets in the universe: 4 sextillion, or 4 x 1021

hen the astronomers add a bit of a twist to the equation:

How low do you have to set the chances that a habitable planet gives rise to a signal-beaming civilization, in order to reduce what you get when you do the multiplication (planets times probability) to just one world? The number would have to be one chance in 4 sextillion, or 2.5 x 10-22. Pretty low contact rates, huh?

In a press release after their explosive conclusion, Frank says: “To me, this implies that other intelligent, technology-producing species very likely have evolved before us, Think of it this way: Before our result you’d be considered a pessimist if you imagined the probability of evolving a civilization on a habitable planet were, say, one in a trillion. But even that guess, one chance in a trillion, implies that what has happened here on Earth with humanity has in fact happened about 10 billion other times over cosmic history!”

Is it just a numbers game, or is this a breakthrough?

 

The above image is from Flickr User Kevin Gill and is licensed under Creative Commons.

The Transit Method Reveals Where We Should Look for Aliens

The search for signs of intelligent, extraterrestrial life continues but a new study suggests exactly where to start. Researchers, as we know, have identified and characterized many possibly habitable alien planets. They did this by utilizing the "transit method". The transit method analyzes how parent stars' light changes when orbiting across these stars' faces from Earth's perspective. This is accomplished via NASA's Kepler space telescope. link

Logically, intelligent aliens could possibly use this same strategy to discover Earth and learn that it has the ability to support life.

Rene Heller, of the Max Planck Institute for Solar System Research in German says, "It's impossible to predict whether extraterrestrials use the same observational techniques as we do...But, they will have to deal with the same physical principles as we do, and Earth solar transits are an obvious method to detect us."

However, according to the rules of cosmic geometry, Earth's solar transits are visible from a limited swath of the sky. This has been dubbed by Ralph Pruditz, a professor of physics and astronomy at McMaster University in Canada, the "transit" zone.

Through this understanding, SETI (Search for Extraterrestrial Intelligence) should focus on this particular swath of space in order to gain the highest chance for contact.

The transit zone contains roughly 100,000 stars, which means there's no shortage of "potential targets for SETI scientists' radio telescopes."

This picture was taken by Flickr user AcidPix and is licensed under the Creative Commons.