# The mass

Who has the mass more - teapot with hot water or with the same amount of cold, from a fixed or a rotating flywheel?

Yes, the mass of hot teapot more than a cold teapot. Yes, the mass of the rotating flywheel with energy is more not rotating flywheel. The extra mass - it is... the energy contained in the hot kettle and a rotating flywheel! How much weighs energy? If the rocket to accelerate to of 10 km/s, the increase in mass is about ten orders of magnitude smaller than the mass of a body at rest. Yes missile in flight and did not weigh! You can weigh the rotating flywheel, but he is able to have a peripheral speed of only 10 times smaller than the rocket, and the extra weight will imperceptible even for the most sensitive scales.

But everything changes when the body is dispersed to a large near-light speeds. Electronic example, can be accelerated to a speed which is only 35-40 km/s is less than the speed of light; mass of the electron is on the increase in 2000, and becomes even more so than the stationary proton. But no body can not accelerate to the speed of light, because it would require an infinitely large energy, and the body itself "will absorb" a mass of the entire universe, that is, the body mass will be infinite! Therefore, you can not really do it.

Only a photon, can race with the speed of light. And it is because the photon alone weighs nothing, since its rest mass is zero. But the mass of the overclocked photon quite specific. It is, however, very small. For example, the energy of a photon of green light 4x10-19 J, and this corresponds to that of the total in 4,4x10-36 kg! The mass of this photon nearly 200,000 times less than the electron! However, with decreasing wavelength of the photon mass is growing, and in gamma rays it can get closer to the electron mass, but still it is not enough!

By the way, despite the fact that such a mass and energy are negligible, the person is able to perceive several, 3 - 4 the quantum, or photon of light!

But how much energy contains a mass of 1 kg? It is very easy to calculate with help the formula of Einstein:

E = mc²,

where m - the mass of the energy, kg; c - the speed of light in a vacuum, or a 3x108 m/s.

Total turns that energy with mass of 1 kg is equivalent to 9x1016 J. A lot or a little?

If 1 kg of gasoline, burning in 15 kg of air, allocates 46,1x106 J, then 1 kg of clean energy corresponds to about 32 million tons gasoline-air mixture! Impressive, is not it? With help this energy can delete a large metropolis with a face of the Earth.

How do you get this energy? In theory, very simple: you need to connect the appropriate mass of particles with a mass corresponding antiparticles, for example, electrons with positrons or protons with antiprotons. You can even connect the material atoms with of antimatter atoms and get annihilation. But to get an antiparticle, or antimatter, although it is possible, but very difficult and expensive.