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Some years ago i read about this equation that helps us estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy.

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Now, i am wondering if there are results from Drake's equation (given that some parameters are extremely hard to be calculated) and if do these reflect the real world?

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  • $\begingroup$ Since none of the values are well constrained, there cannot be a fixed value for the result. $\endgroup$
    – Kyle Kanos
    Commented Jul 11, 2014 at 16:15
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    $\begingroup$ But there are results. Right? $\endgroup$
    – George Smyridis
    Commented Jul 11, 2014 at 16:20
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    $\begingroup$ It is an equation, not an "equation". It has a left side and a right side that are equal. It is dimensionally correct. Equations are not guaranteed to give results that reflect the real world, they are only as good as the ideas they encode, but calling it an "equation" makes it sound vague, while it is in fact precise (even if the values that you might enter into it are not). $\endgroup$
    – Kyle Oman
    Commented Jul 11, 2014 at 17:12
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    $\begingroup$ It is obviously only as fixed as the least well understood parameter. Which is to say it's not fixed much at all because we have nearly no data on any parameters relating to the rise of life, intelligence and civilization. $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Jul 11, 2014 at 18:26

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The Wikipedia article on the Drake equation includes a section giving the current estimates for its parameters. I won't copy and paste the text here: suffice to say that $R_*$ and $f_p$ are reasonably well known. We're beginning to get a handle on $n_e$ from the exoplanet surveys. However we have little or no experimental evidence to assign values to any of the other parameters, though it's widely believed that $f_\ell \approx 1$.

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Well, it is known that $N \geq 1$ (^o^)

On a more serious note, the Kepler Space telescope is providing greatly improved estimates of the parameters $f_p$ and $n_e$.

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Based on the Wiki article, we're looking at something on the order of millions for $N$ just in our galaxy. So far, we see there to only be us. This could be the result of a failure in the theory that led to the Drake Equation, or a lack of knowledge regarding the parameters. We really don't know too much regarding the parameters, thus extensive efforts are being made to obtain more accurate, parametric depictions of reality w.r.t the number of communicative civilizations.

But if $N$ is in the millions just for our galaxy, then where is everyone?! We look up and see nothing! This is the Fermi Paradox.

A theory is regarded as a good descriptor of the real, physical world, when its predictions explain, and match observations. At the moment, the Drake Equation doesn't. What it has done however is motivate our race to find others somewhat like us, which will in turn allow us to tweak the theory so that it yields consistent predictions.

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I think the importance of this equation may sometimes be somewhat overestimated. The importance is not so much the actual number (well, if we could calculate it with any significant certainty it would be), but more a piece of mind: it makes you think about which factors are important in the hunt for extraterrestrial life.

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