Where I live it is very common to see jackets and T-shirts with familiar yet casually garbled or modified content (example)

I recently spotted what looked a lot like the Drake equation on the back of a motorcycle, shown in the photo.

Here is the equation from Wikipedia (more here):

$$N \ = \ R_* \ f_p \ n_e \ f_l \ f_i \ f_c \ L$$

and here is what I can make out from the photo

$$N \ = \ R_* \ f_p \ n_e \ f_l \ X \ X \ L \ B_X$$

where $X$ represents something I can't read, and note that there is a $B$ at the end that doesn't appear in the Wikipedia version.

There are also unspecified callouts on the $N, n_e, B$ and the first "$X$".

The sleeve also contains text which is only partly visible:


Question: Does this representation seem to reflect a serious new or alternate version of the Drake equation, or is it better or more likely characterized as "art" or graffiti?

jacket with some version of the Drake Equation

  • 1
    $\begingroup$ You can barely spot the G on the sleeve... $\endgroup$
    – WarpPrime
    Commented Feb 19, 2021 at 2:06
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    $\begingroup$ Don't get to concerned about the Drake Equation, from what I read in the recent past, I forget the source, but Drake never had any intentions for his equation to be the definitive equation. The story goes is he was preparing for a conference or small meeting of peers/friends & he wrote the equation as means of a discussion starter to get people thinking about the issue. It turned out to be a very good equation & no-one has bothered to develop as serious alternative. $\endgroup$
    – Fred
    Commented Feb 19, 2021 at 9:27
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    $\begingroup$ The Drake equation isn't much serious itself, isn't? $\endgroup$
    – Alchimista
    Commented Feb 19, 2021 at 10:24
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    $\begingroup$ Wow. I mean, running around in a parka that sports the Drake equation is kinda nerdy. Running around in a Parka with Randall's insightful joke/no joke on it ... that is ... so very ... cool. $\endgroup$ Commented Feb 19, 2021 at 17:05
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    $\begingroup$ @Alchimista: It depends on what you mean by "serious." It's correct, insofar as the mathematics and cosmological theory goes, but the main problem is that the error bars for some of the terms are absolutely massive (and others are highly speculative - they cannot be meaningfully measured until after we've already determined whether aliens exist or not). So in practical terms, all it really says is "we might or might not reasonably expect to encounter aliens," which is not particularly helpful information. OTOH, it does make an argument that "the numbers we have don't rule out aliens." $\endgroup$
    – Kevin
    Commented Feb 19, 2021 at 23:26

1 Answer 1


Given the font, it's xkcd 384, The Drake Equation.

The two $X$'s are the other $f$ terms from the original Drake equation, while the $B_S$ is "amount of bullshit you're willing to buy from Frank Drake"

  • 13
    $\begingroup$ Wow, @Rob, that was a cool answer. "Given the font" :-) $\endgroup$
    – B--rian
    Commented Feb 19, 2021 at 8:50
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    $\begingroup$ bingo! even explains the text on the arm, thanks! $\endgroup$
    – uhoh
    Commented Feb 19, 2021 at 9:46
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    $\begingroup$ @B--rian I've used it one or twice but couldn't recognize it if it bit me. 1, 2 $\endgroup$
    – uhoh
    Commented Feb 19, 2021 at 9:48
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    $\begingroup$ And the sleeve presumably says something like "NUMBER OF COMMUNICATING CIVILIZATIONS IN OUR GALAXY" $\endgroup$
    – Barmar
    Commented Feb 19, 2021 at 14:52
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    $\begingroup$ On xkcd it is $B_S$ not $B_6$ I've edited, hope that's okay. (although in the handwritten lettering it is hard to see) See also explainxkcd.com/wiki/index.php/384:_The_Drake_Equation $\endgroup$
    – James K
    Commented Feb 19, 2021 at 21:01

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