The Drake equation

As anyone can tell by reading my previous posts, the subject of alien civilization has been on my mind lately. So it was an interesting coincidence that I met Frank Drake recently at the University of Santa Cruz in California. He was the narrator for the Perpetual Motion show about Galileo, created by my wife’s group Galileo’s Daughters, for which I mix the visuals, using video and animation.

Frank was very nice to indulge me with my probing questions after the show. His steadfast and educated opinion about the existence of alien civilization is intriguing. Over fifty years ago (1961) Frank wrote the now famous equation that bears his name:

This equation allowed him to make an educated estimate of the number (N) of civilizations out in our galaxy, by using facts such as the number of stars in the Milkyway, the typical life of a civilization in years, and the life time of a typical star. He then adds a couple of  variables: stars with habitable planets, with a fraction of them where sentient civilization arises. Following these you can get to a number that is based in rational thinking. It became the base of the SETI research (search for extraterrestrial intelligence).

All these variables are subject to discussion and arguments, but at the time, Frank Drake estimated that a worst-to-best case scenario would be 1000 to 100,000,000 civilizations. This estimate was made in the early 1960’s, long before the current treasure trove astronomers now utilize to detect planets by using the two following methods: telescopes using the “Doppler” effect, which is the influence that planets have on their star by gravitationally pulling on them; and the even more prolific method using the Kepler space telescope, which detects  light dimming created by a planet’s obscuring the light of their star as they pass in front of it (a minuscule dip, but the sensitivity of these instruments detecting this event is phenomenal).

So, if anything, the pendulum has swung towards the larger number, and ideas about how to detect these civilizations are growing. There is one possible way that was suggested recently, which had to do with the propulsion of spacecrafts using lasers and light sails. And that idea has just become a lot more real! Read this:

The Russian philanthropist Yuri Milner, who I mentioned in an earlier post, has just pledged $100,000,000 of seed money to develop a flotilla (1000) of micro probes, propelled by laser pulses applying light pressure on the sail of each of the probes to accelerate to one-fifth of the speed of light (taking 2 minutes to accelerate from 0 to 37,000 miles per minute). This would be enough speed to reach the next closest star “Proxima Centauri” in twenty years. It is a double star and appears to have at least one planet in the habitable “Goldilocks” zone, (where water is in its liquid form).

One of the sponsors of this expedition is Freeman Dyson, the one with the concept of the Dyson Sphere. Freeman, a true original forward-thinker, had devised a few decades earlier the idea of the “Cosmic Egg“, a miniature spacecraft filled with nanobots that would hop from world to world, find what it needs to replicate itself (indeed, a little ‘cosmic egg’ factory) and then move on to the next. There is no way anything bigger than an iPhone can get to the next star in a reasonable time frame.

On the other side of that “cosmic coin”, the laser pulses (moving at the speed of light) used to propel these probes would be detectable five times sooner than the probes themselves in reaching Proxima Centauri. These pulses being emitted into the universe is a mode of transportation. It has recently been suggested that we could look for these pulses in other solar systems, as they are detectable. The fact that we are planning such a system makes it even more likely that others would be as well.

Alternatively, the same laser technology could be used to hide a civilization from being detected. If any civilization is choosing to do this, it would mean that they know something we only suspect: that there are others to hide from…

imageRonn MacFarlane, Marc Wagnon, Frank Drake, Sarah Pillow and Mary Anne Ballard

Meeting someone like Frank Drake, who has taken this eventuality to such a level is inspiring. Hopefully this civilization, ours, will live long and prosper.