♻ ?
It is the most famous equation in the world. Many can recite it—and attribute it to Albert Einstein—but few know its significance.
It tells us that mass and energy are related, and, in those rare instances where mass is converted totally into energy, how much energy that will be. The elegance with which it ties together three disparate parts of nature—energy, the speed of light and mass—is profound.
Here is where the equation of all equations comes from:
Known for some time before Einstein's insights that electromagnetic radiation (light, for example) possessed momentum. This quality of radiation is small in magnitude—after all, you needn't worry about being knocked over by sunlight—but easily measurable. Applying an understanding of light's momentum within a little thought experiment, it is possible to see how E = mc2 comes about.