Wolfram Alpha's take on the Drake Equation

One of the things I love so much about the Drake equation is how it's all so much bullshit.<p>Before you downvote me, I think it's a great equation and I don't have problems with folks using it. As long as you know what you are doing. really, think about it, all it actually says is that there is this list of things that we feel have to happen in order to determine communicating civilizations, and given any random set of probabilities for a list of things, you multiply them together to get an aggregate answer. It doesn't address whether the list is complete, or overly complex, or mis-stated. The numbers provided are juts best guesses. It's just "multiply a bunch of numbers together and get a new number"<p>I love it. It's definitely not science -- yet it has this cool-looking formula involved. It also has a powerful impact on folks who use it.<p>Drake is really cool in that it gets people thinking about how likely ET is. For that, it's a wonderful tool. But at its heart there's really not much there. At least yet. Perhaps in the future we'll have some solid survey results to put in, especially with Kepler online. Can't wait to start seeing those results coming in.

Its interesting that Alpha has the equation baked in. What would be more interesting would be to see a regularly updated version of this with the latest cosmological data coming in from telescopes like Kepler. Over the next 3-5 years, Kepler is going to be finding Earth-size planets that exist in their star's habitable zones.<p>For those not familiar with how Kepler is finding planets, I'll explain. Basically, Kepler looks for planets transiting in front of their stars. The telescope watches for dips in the star's light. If the planet has an atmosphere, in some cases it can even get an idea of some of the gases from the light.<p>The reason that astronomers aren't expecting to find Earth-size worlds in the habitable zones is that they have to wait for several transits to know for sure they've seen a planet. The reason that most of the planets found to date have been gas giants orbiting very close to their stars is that it only takes a few weeks or months for them to transit the star several times. Astronomers can see one transit, but have to wait for a 2nd to hypothesize a planet is found, and have to see a 3rd or more transit to verify the planet is real.<p>So Kepler has likely already detected suspected Earth-size planets in habitable zones around at least a few stars. However, the telescope has to watch for several years to confirm the transits. Imagine an astronomer in another solar system that has seen Earth transit the Sun. They would have to wait 3-4 years to see Earth transit the Sun several times to confirm our existence.<p>Edit: Meant to include this earlier. There are multiple ways to detect exoplanets, including the transit method. <a href="http://en.wikipedia.org/wiki/Methods_of_detecting_extrasolar_planets#Transit_method" rel="nofollow">http://en.wikipedia.org/wiki/Methods_of_detecting_extrasolar...</a>

If I had a buck for every distinct interpretation of values for the Drake Equation, I wouldn't need to grade homework for a living.<p>Whether this is a comment on the Drake Equation or my salary is an exercise left to the reader :)

What's really depressing is if you assume the number of communicating civilizations is 1 and make average lifetime of communicating civilizations be the free variable.

note that the drake equation gives the number of <i>currently</i> communicating civilizations.<p>if you think there are 10 communicating civilizations now, each communicating for 10000 years, then there should have been quite a few such civilizations in the 13000000000 year history of our milky way galaxy.<p>if the parameters provided apply for 1% of the milky ways history, we would expect 13000 communicating civilizations in total.<p>i would imagine any communicating civilization lasting 10000 years would also develop self reproducing space probes, thus becoming a permanent feature.

The best response to the Drake opinion, IMO, is Tipler's point that if even one civilization created and sent out a von Neumann machine just a million years ago, they'd be here by now. So the fact that we don't see them all over suggests that they do not exist at all.<p>See <a href="http://en.wikipedia.org/wiki/Von_Neumann_probe#Implications_for_Fermi.27s_paradox" rel="nofollow">http://en.wikipedia.org/wiki/Von_Neumann_probe#Implications_...</a>.<p>It should be noted that if our civilization survives another few hundred years, we are likely to send out von Neumann machines.

The Drake Equation's most telling fault, for me, is the "average lifetime of communicating civilizations".<p>The default is 10,000 years. That results in 10 civilizations. A 1,000 year lifespan means there is only 1 civilization, and a 100,000 year lifespan means there are 100 civilizations.<p>As if we have any idea how long a communicating alien civilization would last. We don't even know how long we will last, and aliens would be completely different to us.

A quick thing to notice, if you fiddle a bit with the variables, you can get the answer "1" to the number of civilisations in our galaxy. Just decrease the probability of life or intelligent life. After all, it took 3 bn. years before the first multicellular life developed on Earth and 1bn. years for intelligence to develop afterwards.

Seems low considering Milky Way has between 200,000,000,000 and 400,000,000,000 stars.

<a href="http://xkcd.com/384" rel="nofollow">http://xkcd.com/384</a>

Why the search of ET Intelligence is of <i>any</i> significance for mankind (or even science for that matter)? Even if we assume that ET life exists, in all likelyhood, after spending billions of trillions of dollars, we may get to know that ET exists (assuming they do), are thousands of light-years away from us.<p>Apart from the curious "are we alone?", does answering this question, has any positive/productive outcome?

That's some optimistic data there.

2 earth like planets per star with planets? that's bold.

Shouldn't the answer be 42?