

Sound Wave Speed
Name: ANG
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 20002001
Question:
What is the Monte Carlo Technique? And why it is so
frequently apply to simulations of experiments in particle physics?
Replies:
Hello,
Monte Carlo technique (named after the gambling haven (or hell) in the
European country of the same name) is the most powerful computational
technique invented to tackle the widest range of problems in physical and
even social sciences (e.g., economics), problems that are too complex,
difficult, and often impossible to solve in any other way.
This is a statistical method, relying on random numbers, probability and
statistics to solve problems.
Its beauty is in its simplicity and its accuracy, accuracy in the sense
that at the expense of a prolonged computational time, as accurate a
result as desired can be obtained.
It is best to illustrate my response with an example.
Suppose on wishes to study how sun rays scatter through a particular kind
of cloud and reach an observer on the ground. To a casual observer looking
habitually and everyday at clouds, this seems trivial. But behind what he
sees there is a complex set of interactions that are next to impossible to
study where it not for the Monte Carlo method.
While formulating the problem and solving it for some simple cloud
geometry and content may be possible, it is impossible to do the same for
an arbitrary shaped cloud with arbitrary kinds of particulates in it. In
such a case, one simulate the problem by taking, say, 100, 1000, 10,000,
or more photons, following their paths as they enter the could, scatter
around according to the laws of scattering, end up getting absorbed or
ejected out of the cloud, and reach an observer's eyes. If one follows
enough of these photons, one obtains a reasonable picture of what is going
on. If one wants more accurate results, then more photons are followed.
Simple, elegant, and powerful.
AK
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
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Update: June 2012

