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Teaching Ideas for Particle Physics

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Particles and relativity.

If you play with two billard balls and make them collide very strongly, suddenly there are four of them on the table. Can you imagine? The two old ones are not moving any more, their energy is "gone".
And then, if the two new balls touch each other they explode and vanish as if a magician had been acting. Can you believe this?

Of course, this doesn't work with billard balls but physicists can really do this macic: They accelerate two electrons to very high speeds and have them collide and suddenly there are four of them. Where do they come from?
And indeed, if the two new electrons get in contact they disappear and leave a flash of energy.

There are two basic principles you shold know about by now:
1. From Chemistry the law of conservation of mass : mass is never changed within a chemical reaction
2. From Physics the law of conservation of energy : energy cannot be produced nor be destroyed.

Are they broken here?
A famous physicist, Albert Einstein, found out that mass indeed can be transferred into energy and vice versa. So mass and energy are basicly the same thing. He wrote down the formula E = m c2 . This means that energy equals mass (multiplied by the sqare of the velocity of light).
So the energy for m = 1 kg (like one liter of milk) is:  E = 1kg * (2.9979*108 m/s)2
E = 89,874,000,000,000,000 J = 89,874,000,000,000 kJ which equals ... megatons of TNT or ... nuclear bombs of the Hiroshima type.
 

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