Vacuum

“If Dirac’s idea restores the stability of the spectrum by introducing a stable vacuum where all negative energy states are occupied, the so-called , it also leads directly to the conclusion that a single-particle interpretation of the Dirac equation is not possible.”

“These rays, as generated in the , are not homogeneous, but consist of bundles of different wave-lengths, analogous to what would be differences of colour could we see them as light. Some pass easily through flesh, but are partially arrested by bone, while others pass with almost equal facility through bone and flesh.”

“Now his principal doctrines were these. That atoms and the vacuum were the beginning of the universe; and that everything else existed only in opinion.”

“Where a calculator like the today is equipped with 18,000 s and weighs 30 tons, computers in the future may have only 1,000 vacuum tubes and perhaps weigh only 1½ tons.”

“When you look at a vacuum in a quantum theory of fields, it isn't exactly nothing.”

“In general, the rate of evaporation (m) of a substance in a high vacuum is related to the pressure (p) of the saturated vapor by the equation Red phosphorus and some other substances probably form exceptions to this rule.”

“It's illegal to make superpositions with different vacua. That's one of the rules of quantum field theory.”

“His reluctance to pay for elaborate or expensive equipment, perhaps the result of an impoverished childhood, had established the legendary "sealing wax-and-string" tradition of the Cavendish, where everyday materials were ingeniously used to make and patch up experimental equipment, with sealing wax proving particularly useful for vacuum seals.”

“[E]xperiments with a simple little machine, designed to mimic certain elementary features of animal behavior... Consisting only of two vacuum tubes, two motors, a photoelectric cell and a touch contact, all enclosed in a tortoise-shaped 'shell, the model was a species of artificial creature which could explore its surroundings and seek out favorable conditions. It was named Machine speculatrix.”

“Some assert that there is absolutely no vacuum; others that, while no continuous vacuum is exhibited in nature, it is to be found distributed in minute portions through air, water, fire and all other substances: and this latter opinion, which we will presently demonstrate to be true from sensible phenomena, we adopt.”

“Vacuum stands and remains a mathematical space. A cube placed in a vacuum would not displace anything, as it would displace air or water in a space already containing those fluids.”

“In a vacuum which is imagined as infinite there cannot be local differences, both on account of its infinity, and also because of the fact that the vacuum, if it exists, would have no nature but a privation, and therefore it can have no natural differences.”

“The space of the real physical world must be considered full, that is a plenum, because a vacuum could have no physical existence.”

“The spooky ether was persistent. It took an Einstein to remove it from the Universe. ...Gradually, over the last twenty years, the vacuum has turned out to be more unusual, more fluid, less empty, and less intangible than even Einstein could have imagined. Its presence is felt on the very smallest and largest dimensions over which the forces of Nature act.”

“The physicist's concept of nothing—the vacuum... began as empty space—the void... turned into a stagnant ether through which all the motions of the Universe swam, vanished in Einstein's hands, then re-emerged in the twentieth-century quantum picture of how Nature works.”

“The quantum revolution showed us why the old picture of a vacuum as an empty box was untenable. ...Gradually, this exotic new picture of quantum nothingness succumbed to experimental exploration... in the form of s, light bulbs and s. Now the 'empty' space itself started to be probed. ...There was always something left: a that permeated every fibre of the Universe.”

“Einstein showed us that the Universe might contain a mysterious form of vacuum energy. ...Last year, two teams of astronomers used Earth's most powerful telescopes... to gather persuasive evidence for the reality of the cosmic . Its effects are dramatic. It is accelerating the expansion of the Universe.”