Mass and Energy
Quite often, physicists want to study massive, unstable particles that
have only a fleeting existence
(such as the very massive top quark.)
However, all that physicists
have around them in the every day world are very
low-mass particles.
How does one perform this amazing
feat of using particles with lesser mass to obtain particles of greater mass?
You know Albert Einstein's famous equation that 
where E is the energy,
m is the mass, and c is
the speed of light. Therefore,
Question: When did Einstein write
?