Читать книгу String Theory For Dummies - Andrew Zimmerman Jones - Страница 87

The matter in our universe would never do anything interesting if it weren’t for the addition of energy. There would be no change from hot to cold or from fast to slow. Energy is also conserved, as scientists discovered throughout the 1800s as they explored the laws of thermodynamics, but the story of energy’s conservation is more elusive than that of matter. You can see matter, but tracking energy proves to be trickier.

Kinetic energy is the energy involved when an object is in motion. Potential energy is the energy contained within an object, waiting to be turned into kinetic energy. It turns out that the total energy — kinetic energy plus potential energy — is conserved any time a physical system undergoes a change.

String theory makes new predictions about physical systems that contain a large amount of energy packed into a very small space. The energies needed for string theory predictions are so large that it may never be possible to construct a device able to generate that much energy and directly test the theory’s new predictions. String theory also works when the energies are small, in which case it reproduces the “usual” laws of gravity, as we expect.