Context and question: In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and also no photons. As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons.) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next.
What is a blackbody photon referred to in quantum mechanics?
Answer: unanswerable
Context and question: In the century after the death of Osman I, Ottoman rule began to extend over the Eastern Mediterranean and the Balkans. Osman's son, Orhan, captured the northwestern Anatolian city of Bursa in 1324, and made it the new capital of the Ottoman state. This Ottoman conquest meant the loss of Byzantine control over northwestern Anatolia. The important city of Thessaloniki was captured from the Venetians in 1387. The Ottoman victory at Kosovo in 1389 effectively marked the end of Serbian power in the region, paving the way for Ottoman expansion into Europe. The Battle of Nicopolis in 1396, widely regarded as the last large-scale crusade of the Middle Ages, failed to stop the advance of the victorious Ottoman Turks.
In what year did Osman's son capture an Anatolian city?
Answer: 1324
Context and question: Meanwhile, Andreas Papandreou founded the Panhellenic Socialist Movement (PASOK) in response to Karamanlis's conservative New Democracy party, with the two political formations alternating in government ever since. Greece rejoined NATO in 1980. Greece became the tenth member of the European Communities (subsequently subsumed by the European Union) on 1 January 1981, ushering in a period of sustained growth. Widespread investments in industrial enterprises and heavy infrastructure, as well as funds from the European Union and growing revenues from tourism, shipping and a fast-growing service sector raised the country's standard of living to unprecedented levels. Traditionally strained relations with neighbouring Turkey improved when successive earthquakes hit both nations in 1999, leading to the lifting of the Greek veto against Turkey's bid for EU membership.
What does PASOK stand for?
Answer:
Panhellenic Socialist Movement