On browsing the Serpentine Gallery of equations one can find the predictable Einstein equations and Standard Model actions, but my favourite was by Neil Gershenfeld: Other beauties include A = A, habitable planets and of course Dyson on the tau function. This last item is really cool: Dyson rediscovered for himself the identity

$\tau (n) = \sum \frac{(a – b)(a – c)(a – d)(a – e)(b – c)(b – d)(b – e)(c – d)(c – e)(d – e)}{1!2!3!4!}$

where $a,b,c,d,e$ are all possible numbers (respectively) equal to $1,2,3,4,5$ mod 5, satisfying

$a + b + c + d + e = 0$

$a^2 + b^2 + c^2 + d^2 + e^2 = 10n$

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## Matti Pitkanen said,

November 2, 2007 @ 10:55 am

For me the x–>z^2+c of Mandelbrot is THE formula of 21st century. For the possibility that Mandelbrot fractal and Julia set could have physical meaning see this.

## Kea said,

November 2, 2007 @ 8:01 pm

Hi Matti! Yeah, that’s a cool one too, but I prefer ones with a more philosophical flavour.

## Pioneer1 said,

November 4, 2007 @ 1:13 am

Lots of thanks for the link to Formulae for the 21st century. I liked all of them. But most of all I liked the idea.

Probably not only people whose job is to think about these things but everyone has such a one page summary of their philosophy.

Their site is done nicely as well. I liked the fact that these are works on paper, mostly handwritten. I thought it would be nice to extend on the idea by starting a similar site. A little research revealed that there is a service called scrapblog

http://scrapblog.com/

that may be used to create a similar site.

I started a scrapbook

http://scrapblog.com/viewer/viewer.aspx?sbId=112190

by putting my formula ðŸ™‚

Do you have one? What do you think about the idea? If people are interested I would even think about designing a professional site like theirs.

Thanks again.

## L. Riofrio said,

November 4, 2007 @ 6:59 am

Everyone at Serpentine seems to have stolen equations from people like Einstein. Have none of the contributors come up with their own equations?

## Pioneer1 said,

November 4, 2007 @ 11:48 am

Everyone at Serpentine seems to have stolen equations from people like Einstein.You have your own equation. Would you contribute to this scarpbook?

http://scrapblog.com/viewer/viewer.aspx?sbId=112190

## Michael Tim said,

February 28, 2009 @ 5:22 pm

I love your site!

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