In physics, special relativity is the generally accepted physical theory regarding the relationship between space and time. It is based on two postulates: (1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelera...
In physics, mass–energy equivalence is the concept that the mass of an object or system is a measure of its energy content. For instance, adding 25 kilowatt-hours (90 megajoules) of any form of energy to any object increases its mass by 1 microgram (an...
Brownian motion or pedesis is the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the quick atoms or molecules in the gas or liquid. This transport phenomenon is named after the botanist Robert Br...
In 1905, Albert Einstein described light as composed of discrete quanta, called photons, rather than continuous waves. Based upon Max Planck's theory of black-body radiation, Einstein theorized that the energy in each quantum of light was equal to the ...