Context: In 1930, Paul Dirac proposed a model of the vacuum as an infinite sea of particles possessing negative energy, called the Dirac sea. This theory helped refine the predictions of his earlier formulated Dirac equation, and successfully predicted the existence of the positron, confirmed two years later. Werner Heisenberg's uncertainty principle formulated in 1927, predict a fundamental limit within which instantaneous position and momentum, or energy and time can be measured. This has far reaching consequences on the "emptiness" of space between particles. In the late 20th century, so-called virtual particles that arise spontaneously from empty space were confirmed.

Question: An infinite sea of particles with negative energy  was a model propesed by whom?
Answer: Paul Dirac

Question: What year was the Dirac sea modeled?
Answer: 1930

Question: When werer virtual particles confirmed?
Answer: late 20th century

Question: What year was the uncertainty principle formed?
Answer: 1927,

Question: What theorized that time and energy can be measured?
Answer: Werner Heisenberg's uncertainty principle

Question: What kind of energy did Werner Heisenberg believe a vacuum held?
Answer: Unanswerable

Question: What did Heisenberg call the particles with negative energy inside a vacuum?
Answer: Unanswerable

Question: What did Heisenberg predict the existence of in 1930?
Answer: Unanswerable

Question: How long did it take for the uncertainty principle by Dirac to be confirmed?
Answer: Unanswerable

Question: What in the late 20th century did Dirac theorize can be measured?
Answer: Unanswerable