# Multipole Question

#### kyle_soule

What is a multipole? or, perhaps, more appropriately, what are multipoles?

The whole subject of multipole algorithms is infinitely unclear to me, so literally any information will be helpful.

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#### Stranger

if this can help.....

http://www-aix.gsi.de/~weick/gico/gicohow/node17.html [Broken]

http://www.mpip-mainz.mpg.de/~gelessus/pubs/pub4.html [Broken]

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#### Mike H

As Sulaiman already provided some good links on the basic idea of what a multipole is, here's a bit of the rest....

Multipole algorithms/methods generally refer to the procedures used to solve problems where you have to find the long-range Coulombic forces from a group of charges via a multipole expansion of the potential. In a more general sense, it's a way to determine pairwise interactions by essentially taking advantage of the symmetry of the problem, dividing the space into grids, and then first calculating within each grid and more or less summing up their subtotals. So, after a fashion, instead of calculating each and every pairwise interaction of a system, you only calculate the pairwise interactions explicitly within the grid so as to save yourself time and CPU/memory capacity.

Added after edit: Sorry about that, Sulaiman. :) I've fixed it now.

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#### Loren Booda

The graviton, having exclusively attractive force of infinite extent, is supposed to emulate a quadrupole in order to generate gravitational waves.

#### Stranger

Can you please call me Sulaiman....thanks

#### kyle_soule

Originally posted by Loren Booda
The graviton, having exclusively attractive force of infinite extent, is supposed to emulate a quadrupole in order to generate gravitational waves.
I was actually wondering what a multipole was because of gravitons Funny you would use that example.

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