The famous equation; E=MC2.  We all know it.  It is, after all, the most famous equation in mathematics and science. It is Einstein’s Theory of Special Relativity.  Energy = mass x the speed of light (squared).


E= Energy

M = Mass

C = Speed of Light (squared)

Most of us are intrigued by big numbers.  Here is a prime example.  The speed of light is 186,000 miles per second which equates to ~ 670 million miles per hour.  That in itself is impressive enough.  At 670 million miles per hour you could make four round trips to our sun and back—93 million miles distant—during the time it takes you to watch two re-runs of the Andy Griffith show!  When you square 670,000,000 you get the stupefying number 448,900,000,000,000,000,000!  No point in even trying to understand a number that contains 17 zeros.  But, one thing is abundantly clear…..a small amount of mass can contain an enormous amount of pent up energy.


What does all this mean in terms that we can understand?  What does the speed of light have to do within a calculation of energy?  How about mass?  How is that involved?

Theory of Special Relativity Simplified

Albert Einstein first proposed his Theory of Special Relativity and the resulting equation—E=MC2—in 1905.  One of the fundamental components of his theory was that matter (mass) and energy are basically two conditions of the same thing. Neither energy nor mass can be destroyed, nor can they be created.  They can only change forms; therefore, the total amount of mass and energy existing within our universe is constant and has been since the “big bang”.  Energy can be converted into matter and vice-versa but the total quantity of both in combination cannot be changed.  Prior to Einstein’s discovery energy and matter had been presumed to be two completely dissimilar components of the cosmos.  This new discovery had a profound impact on our understanding of energy.  It became clear that massive amounts of energy were available at the atomic level.

Massive Energy

What is “massive” energy?

“The most powerful nuclear explosion in history — the Tsar Bomba — which released nearly 60 MegaTons of energy, converted less than 50 grams (under 2 ounces) of mass into energy”.

E=MC2, Special Theory of Relativity-Hydrogen Bomb

Hydrogen Bomb Explosion


Another principle tenet of E=MC2 is that the speed of light is constant, regardless of whether the source of light is moving toward or away from the observer.  The theory also stipulates that time slows down as velocity increases. We have all seen movies and/or read books where characters leave the earth, travel for a period of time at or near light speed, and return to find that everyone on earth has aged dramatically while the light traveler’s ages have not changed.  This is not mere fancy.  Einstein’s theory predicts this phenomena.  The only minor caveat is that we would actually need to figure out how to travel at near light speed to make one of those old Twilight Zone episodes a reality.

Why is the speed of light a factor in E=MC2?  The simple answer is that when matter—of any type– is converted from its present state to a state of pure energy that energy will be traveling at the speed of light.

Einstein’s relativity theories also unified the relationship between space and time.  In addition to the three known dimensions of space his theory stipulated a fourth dimension….time.  The birth of what became know as the space-time continuum.


Practical Implications of E=MC2

Nuclear energy would not be possible without the truth of E=MC2.  Love it or fear it, the reality is that without high-efficiency nuclear energy our consumption of fossil fuels would be even greater than it is today.  The understanding of the equation was also the bedrock for the eventual development of nuclear weaponry.

E=MC2 has also been put to more benign applications.  Radiocarbon dating is a by-product of the equation.  Several technologies within the medical field were also made possible by E=MC2.


Einstein’s Theory of Special Relativity…a stunningly elegant, yet revolutionary, equation from one of humankind’s greatest minds.  




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