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.”

• “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.”

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

• “No planet or star or galaxy can be typical, because the Cosmos is mostly empty. The only typical place is within the vast, cold, universal vacuum, the everlasting night of intergalactic space, a place so strange and desolate that, by comparison, planets and stars and galaxies seem achingly rare and lovely.”

• “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.”

• “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.”

Quotes via Wikiquote (CC BY-SA), each with its original source.