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I asked this question because of Einstein's equation, he derived an equation saying that solid things are packed ENERGY. So lets think that solid is energy,then why we are not using it for our purposes? It means that we are surrounded by energy and only need is to change it in another form. Another important question: How can a human predict or derive an equation which has square of speed of light in his equation? $E=mc^2.$

      NOTE: MASS word in QUESTION doesn't means liquid fuel or coal etc.
Qmechanic
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Haroon Haider
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1 Answers1

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So lets think that solid is energy, then why we are not using it for our purposes?

We are.

In civilian nuclear energy production, atoms of (usually) Uranium-235, are being split ('fissioned' in the nuclear jargon) into fission products.

There is a small mass difference between the original fissile atoms (U-235) and the fission products:

$$m_{fissile}-m_{fissioned}>0.$$

And that difference has been converted to energy according to:

$$E=(m_{fissile}-m_{fissioned})c^2.$$

Consider $c^2$ a proportionality constant and because $c$ is large only small amounts of mass need to be converted to get appreciable amounts of energy.

Mass is converted to energy (and vice versa) all the time, even in everyday processes: when you wind up a Grandfather's clock (charge it with energy), it becomes slightly heavier (albeit only imperceptibly little).

To convert mass to energy at an appreciable (i.e. commercially viable) rate we need to tap into the strongest forces in nature: the nuclear forces. Hence the generation of nuclear energy.

Gert
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  • And just to finish it off, the derivation of the energy formula: https://en.m.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence#The_first_derivation_by_Einstein_.281905.2 –  Oct 29 '15 at 02:43
  • @Gert can you please also explain 2nd question?how world believed in the Einstein equation because he didn't performed it practically :) – Haroon Haider Oct 29 '15 at 19:02
  • @HaroonHaider: Albert Einstein was a theoretical physicist but there's almost no aspect of his work that hasn't been empirically verified. One of the first 'test' of mass energy equivalence came with Otto Hahn and Lise Meitner's discovery of uranium fission. – Gert Oct 29 '15 at 19:14