# What is this equation, written on a wall? [closed]

I've also asked this in MathOverflow, but since the equation in question is related to acceleration and physical phenomenon, I figure this is also a good place.

I was asked to ID the following, but can't figure out what it's for. Laplace Transform of acceleration (x double-dot)?

(Sorry that I can't provide a sharper image - this is all I have access to)

I don't recognize the infinite sum, and there are some squiggles around the r in the denominator that I can't quite make out.

I tried to transcribe it, but since I'm not entirely sure what's going on in the denominator, I can't be certain it's accurate.

It seems odd to me to see a negative exponent in the denominator, and it's confusing using i as a counting variable.

Context

There is none. This was sent to me by a friend, off of a "what is this" site. No known artist, location, date, etc.

Edit #1

It seems that the double closed integral is from infinity to phi. But still not much help.

Edit #2 - Re-done Equation with "knowns"

Based on some comments, and things not previously seen/added to original transcribed equation, I've got the following:

The changes aren't substantial. The coefficient for the r' in the denominator has been proposed as being n, or 2. Additionally, having stared at this a bit longer, the two 2 exponents could also be sloppily-written thetas. Probably not.

All-in-all, it seems that this is most likely trolling.

## closed as off-topic by sammy gerbil, Jon Custer, Kyle Kanos, ACuriousMind♦Jul 6 '17 at 21:07

• This question does not appear to be about physics within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

• I'm voting to close this question as off-topic because this is not a question about physics. – sammy gerbil Jul 6 '17 at 18:56
• Why do you think the equation relates to acceleration and a physical phenomenon? – sammy gerbil Jul 6 '17 at 18:57
• @sammygerbil I suppose an odd usage of variables, by the original artist, could mean otherwise. That being said, I've yet to see an x double-dot that was anything other than acceleration. The dots above the x are not just to represent derivatives, but more specifically derivatives with respect to time. The second derivative of x wrt time is: acceleration. Acceleration, position, radii of curvature (i.e. r), all point to physics. – Birrel Jul 6 '17 at 19:08
• The comment by Willie Wong in MathOverflow seems to me the best interpretation (xkcd.com/356). – sammy gerbil Jul 6 '17 at 19:47

• @Joshua $x$ on the RHS is a dummy variable (in your equation and that in the photo), it disappears when the definite integral is performed. The argument of the RHS is $\phi$, not $x$. – sammy gerbil Jul 6 '17 at 19:45