This C program measures acceleration due to gravity. When run without any arguments, it prints the exact value of g in SI units (m/s2).
Instructions: download the program text, save it to a file, compile and run it. It is very important that you preserve the formatting (if you delete or add a single newline, the program will not work!) #define O +\ must be the first line in the .c file.
#define O +\
__LI\
NE__\
,46-\
__LI\
NE__
char
g[]
={
46
O O
O
O
O
O
O
};main( ){puts(g);}
To understand the program, print out the source and look at it from some distance. The apparatus at the top is the particle dispenser; O's are falling particles, and at the bottom there's a photodector connected to a very precise timer. The program works by measuring the time it takes for a particle to fall from the top of the program to the bottom.
You can reproduce Galileo's famous experiment by changing O to another letter and verifying that the value of acceleration doesn't change.
FIXME: current version of the program works only on Earth; support for other planets will be added in later revisions. If you live on Mars and want to be a beta-tester, please contact me.
;)