Difficult in layman's term but I will give it a go:<br /><br />Everything in the universe is made either of matter or energy and they can interchange. <br /><br />You are used to see Matter changing into Energy everyday: the Sun is the perfect example.<br /><br />Not so common is Energy being coverted into Matter.<br /><br />This is where Einstein comes in. Einstein’s E=mc² says we can even turn energy into matter! <br /><br />Particle physicists make this kind of reaction happen every day in laboratories. This accomplished by accelerating ordinary particles up to <font color="black">very high speeds, close to the speed of light</font> and smashing them into each other. The result is a spray of new particles, many of which may be heavier than the original pair that collided. The energy of motion of the orignal particles has contributed to creating new ones. Some of these new particles are very interesting and exotic! Most only live for a short time before decaying into more ordinary stuff. <br /><br />
E=mc²<br /><br />c² is also the conversion factor required to sometimes convert from units of mass to units of energy, i.e. the energy per unit mass. <br /><br />In unit-specific terms:<br /><br />E (joules or kg·m²/s²) = m (kilograms) multiplied by (299,792,458 m/s)2.<br /><br />A gram of mass could (theoretically) be converted entirely into approximately:<br />90,000,000,000,000 Joules (90 terajoules)<br />25,000,000 kilowatt-hours<br />The energy in 21 kilotons of TNT<br />Approximately 0.0000850 Quads (quadrillion British thermal units)