Hawking's Equation

awking has written down an equation which looks rather like Planck's equation. Hawking's equation is S = kA, where S is the entropy of a black hole, A is the area of its surface, and k is a constant which I call Hawking's constant. Entropy means roughly the same thing as the heat capacity of an object. It is measured in units of calories per degree. A is measured in square centimeters. Hawking's equation says that entropy is really the same thing as area. The exchange rate between area and en...

 Dyson Spheres

The material factors which ultimately limit the expansion of a technically advanced species are the supply of matter and the supply of energy. At present the material resources being exploited by the human species are roughly limited to the biosphere of the earth, a mass of the order of 5 X 10^19 grams. Our present energy supply may be generously estimated at 10^20 ergs per second. The quantities of matter and energy which might conceivably become accessible to us within the solar system are ...

 Neutrinos

Neutrinos were first predicted to exist as the result of a puzzle related to the decay of neutrons. While neutrons are stable inside atomic nuclei, free neutrons are observed to decay, in an average time of about 10 minutes, into protons and electrons. The electric charge works out fine, because a neutron is electrically neutral, while a proton has a positive charge and an electron an equal and opposite negative charge. The mass of a proton plus an electron is almost as much as the mass of a ...