The well-known Drake equation, created by Dr. Frank Drake in 1960 to predict the number of extraterrestrial civilizations in the Milky Way, gets an upgrade to take into account the concept of multiple universes. Turns out our knowledge is so limited as to make the exercise essentially impossible.
From the second link:
But there’s a problem: this is not an equation. To form a true Drake-like argument, Gleiser would need to assign probabilities to each of these sets allowing him to write an equation in which the assigned probabilities multiplied together, on one side of the equation, equal the fraction of universes where complex life emerges on the other side.
Here he comes up against one of the great problems of modern cosmology–that without evidence to back up their veracity, many ideas in modern cosmology are little more than philosophy. So assigning a probability to the fraction of universes in the multiverse in which the fundamental constants and laws satisfy the anthropic principle is not just hard, but almost impossible to formulate at all.
Also:
Gleiser’s take on the Drake equation for the Multiverse is an interesting approach. What it tells us, however, is that our limited understanding of the universe today does not allow us to make any reasonable estimate of the number of intelligent lifeforms in the multiverse (more than one). And given the limits on what we can ever know about other universes, it’s likely that we’ll never be able to do much better than that.
David Kirkpatrick 
I couldn’t agree more concerning the comment: “without evidence to back up their veracity, many ideas in modern cosmology are little more than philosophy.”
Here’s some philosophy for you that supports that: Given the huge distances in space, and given the limitation of the speed of light, and given the fact that the NEAREST STAR (Alpha Centuri) is 4.5 light years away; then how do we know for sure that the Universe even exists at this exact moment in time? After all, it could all have disappeared some time ago, couldn’t it – for unknown reasons (same unknown reasons that saw it spring into existance, some time ago), and we just don’t know that it’s gone (yet)- us not having been informed due to the limitations of light speed.
Now look here! If the latest light that we see is 4.5 years old (from Alpha Centuri),suppose that Alpha Centuri disappeared 4.6 years ago, then – while we don’t know it yet – the light from Alpha Centuri won’t be there for us a month from now, will it? Now, apply this revelation to the entire Universe. How do we really know that the entire Universe did not just suddenly disappear, say, 5.0 years or more, ago? Just snuffed out. We would have no idea that it had occured, would we, since all the stars that we see in Earth’s sky this evening (other than A.C.) began streaming their light toward us longer ago than 4.5 years. Now, suppose that there is nothing out there but darkness, right now – all the stars without exception having gone out like candles, say, some twenty years ago – but because we on Earth are still seeing that old original starlight that started streaming at us from 4.5+ years ago, we continue to think that “nothing has changed”. In reality, six months from now, the entire sky will go dark -and then we will know that the Universe has been snuffed out!
(Wow! This stuff makes my head hurt!)
Comment by The Wiseman — February 10, 2010 @ 5:44 pm