ch6

If you were to unleash all the energy in your body, you’d generate an explosion equivalent to 30 hydrogen bombs.

Put very, very simply, E = mc2 explains how mass and energy are pretty much the same thing. Mass is simply potential energy ready to be unleashed.

As the name suggests, spacetime combines the three dimensions of space with a fourth dimension: time. In other words, space and time are elements of the same entity.

One helpful analogy is to think of it as a sheet of stretched rubber. This sheet is flat, but it’s malleable – it can warp and bend.

Gravity is actually the curving of spacetime. Objects with more mass curve it more. As smaller objects pass through spacetime, they end up following these curves; this, basically put, is gravity.

If you place a big, round object – say a bowling ball – in the middle of the sheet, the sheet will stretch and sag. This is how massive objects, like the sun, stretch and curve spacetime. Imagine you roll a marble across the sheet. It will try its best to travel in a straight line. However, as the marble nears the bowling ball it will begin to veer off course. It will start to follow the slope made by the heavier object. Soon, the marble will end up going around and around the curve in the rubber sheet – just as the planets orbit the sun.