What does e=mc2 mean?

Answer 1

Einstein figured out the famous formula e=mc² which says that the energy that could be liberated when breaking up atomic nuclei is a whole lotta energy (e) , equal to the mass (m), multiplied by the square of the speed of light (c) which is a very very high number.

He was a leader amongst physicists around the world, and all his colleagues were expanding on his original work. In 1939 two of his colleagues in the USA, Fermi and Szilard from Columbia University in Manhattan, NYC wrote a paper that hypothesized a way to construct an atom bomb using the heavy element uranium as the nuclear explosive.

As soon as Einstein learned about this, he became quite concerned and wrote to president Roosevelt. The USA was at war with Japan and Germany and Einstein realized that someone somewhere was going to use the information in this paper to construct this bomb that would be the ultimate weapon of the time and would win the war for the nation that used it first.

This lead to the top secret Manhattan Project whose mission was to make that bomb. They made it and the rest is history.

I think this is the true practical meaning of e=mc². It is the equation that changed history. It changed the world. It hastened the end of the second World War, and it lead to nuclear power plants and the US-USSR arms race. It lead to the mess we're in now with nuclear proliferation.

The rest, theoretic physics, spacetime, black holes, stellar dynamics, etc is mostly window dressing with little practical meaning, as yet.

Answer 2

E = mc²

E = energy in Joules

m = mass in kilograms

c = the speed of light in m/s: 3.00e8 m/s (300 million m/s)

So, let's say that you have a mole of deuterium atoms (that is, H-2 atoms) whose mass is 2.014101778 grams (that's 2.014e-3 kg, since we're going to need to convert eventually anyway). And let's say that you also have a mole of tritium atoms (H-3) whose mass is 3.0160492675 grams (or 3.016e-3 kg). Now, let's suppose you slam them together to create a mole of helium-4 (4.0026032497 grams, or 4.003e-3 kg) and a mole of free neutrons (1.009e-3 kg). So the mass going in (5.030e-3 kg) is greater than the mass coming out (5.012e-3 kg) by about 1.8e-5 kg. That missing mass turns into energy. How much energy? That question is answered by the equation E = mc²

E = (1.8e-5 kg)(3.00e8 m/s)²

E = 1.6e12 J

So, something like 1/3 of a kiloton of TNT can be released just by the fusion of a few grams of heavy hydrogen. That's obviously a big energy payoff for a very small mass investment. And that, in a nutshell, is what E=mc² means.

Answer 3

It is Einstein's famous equation that links energy directly to mass. This simple equation shows, among other things, how stars can put out so much energy for so many billions of years.

The e means "energy" (in specific units called "joules" - don't worry about that).
The m means "mass" (measured in kilograms).
The c means "speed of light" (it comes from the Latin 'celeritas' meaning light).
The equation basically means that a small amount of mass is equivalent to a VERY large amount of energy.

As an example, if you have a 1 gram mass (approximately the mass of a U.S. dollar bill) is equivalent to the following amounts of energy:
24.9 million kilowatt-hours, or
21.5 million million calories, or
21.5 kilotons of TNT, or
85.2 billion BTUs.

Stars fuse hydrogen to helium, and in so doing a small amount of mass is converted to energy - this equation explains how so much energy is produced from a small amount of mass.

Answer 4

E=Mc square means Energy is equal to mass multiplied by velocity of light that is 300,000 KM/secSquare.
Massx 300,000x300,000.
So even a small mass can produce huge energy. That is happening in Atom/hydrogen bombs.
Chandramohan

Answer 5

It's one of those things that is a good deal
deeper than it first appears.
On the first level it states that
Energy = Mass x C ^2. ... - (Mass = LOTSA energy)

If you expand it you see that it relates
mass, energy, (or matter /energy), and
time, & distance, (or space/time),
in a specific way.
And that is a very deep concept indeed.

Answer 6

It means that if you converted mass to energy, it would be equal to that mass times the square of the speed of light.

Nuclear fission and fusion turn small amounts of mass into large amounts of energy.

Answer 7

The quantity of energy equals the quantity of matter times the speed of light squared.

Answer 8

energy = mass x speed of light squared

Answer 9

energy= mass times light squared?
i think the C is light.

Answer 10

it means mass- energy equivalence