The Most Famous Equation in Physics
In 1905, Albert Einstein published his theory of Special Relativity, which included a revolutionary concept: Mass and Energy are not two separate things; they are two forms of the exact same underlying stuff.
This is expressed in the world's most famous equation, $E = mc^2$. It states that the "rest energy" ($E$) of any object is equal to its mass ($m$) multiplied by the speed of light squared ($c^2$).
The Staggering Power of Mass
Because the speed of light is a massive number ($300,000,000 , \text{m/s}$), and the equation squares it ($90,000,000,000,000,000$), even a tiny speck of mass contains an incomprehensible amount of locked-away energy.
If you could perfectly convert just $1 , \text{gram}$ of matter (the weight of a paperclip) into pure energy, it would release roughly the same amount of energy as the atomic bomb dropped on Hiroshima.
The Formula
Example Calculation
Calculate the total rest energy contained within an average adult human ($70 , \text{kg}$).
- Speed of Light Squared: $(299,792,458)^2 \approx 8.987 \times 10^{16} , \text{m}^2/\text{s}^2$.
- Multiply by Mass: $70 \times (8.987 \times 10^{16}) \approx 6.29 \times 10^{18} , \text{Joules}$.
This is enough energy to power the entire United States grid for several weeks.