Albert Einstein proposed that the laws of physics should be based on the principle of relativity. This principle holds that the rules of physics must be the same for all observers, regardless of the frame of reference that is used, and that light propagates at the same speed in all reference frames. This theory was motivated by Maxwell's equations, which show that electromagnetic waves propagate in a vacuum at the speed of light. However, Maxwell's equations give no indication of what this speed is relative to. Prior to Einstein, it was thought that this speed was relative to a fixed medium, called the luminiferous ether. In contrast, the theory of special relativity postulates that light propagates at the speed of light in all inertial frames, and examines the implications of this postulate.
The principle of relativity holds that the rules of physics must be the same for who?
all observers

Input: Han dynasty
To pay for his military campaigns and colonial expansion, Emperor Wu nationalized several private industries. He created central government monopolies administered largely by former merchants. These monopolies included salt, iron, and liquor production, as well as bronze-coin currency. The liquor monopoly lasted only from 98 to 81 BC, and the salt and iron monopolies were eventually abolished in early Eastern Han. The issuing of coinage remained a central government monopoly throughout the rest of the Han dynasty. The government monopolies were eventually repealed when a political faction known as the Reformists gained greater influence in the court. The Reformists opposed the Modernist faction that had dominated court politics in Emperor Wu's reign and during the subsequent regency of Huo Guang (d. 68 BC). The Modernists argued for an aggressive and expansionary foreign policy supported by revenues from heavy government intervention in the private economy. The Reformists, however, overturned these policies, favoring a cautious, non-expansionary approach to foreign policy, frugal budget reform, and lower tax-rates imposed on private entrepreneurs.

When was the liquor monopoly abolished?
Output: 81 BC

Input: Article: To begin with, England had no permanent home stadium. They joined FIFA in 1906 and played their first ever games against countries other than the Home Nations on a tour of Central Europe in 1908. Wembley Stadium was opened in 1923 and became their home ground. The relationship between England and FIFA became strained, and this resulted in their departure from FIFA in 1928, before they rejoined in 1946. As a result, they did not compete in a World Cup until 1950, in which they were beaten in a 10 defeat by the United States, failing to get past the first round in one of the most embarrassing defeats in the team's history.

Now answer this question: In which year did England join FIFA?

Output: 1906

Article: The legal status of Roman citizenship was limited and was a vital prerequisite to possessing many important legal rights such as the right to trial and appeal, to marry, to vote, to hold office, to enter binding contracts, and to special tax exemptions. An adult male citizen with the full complement of legal and political rights was called "optimo jure." The optimo jure elected their assemblies, whereupon the assemblies elected magistrates, enacted legislation, presided over trials in capital cases, declared war and peace, and forged or dissolved treaties. There were two types of legislative assemblies. The first was the comitia ("committees"), which were assemblies of all optimo jure. The second was the concilia ("councils"), which were assemblies of specific groups of optimo jure.

Question: Who did the assemblies elected by the optimo jure elect?
Ans: magistrates

Here is a question about this article: Ethnic Russians constitute 25.5% of the country's current population and 58.6% of the native Estonian population is also able to speak Russian. In all, 67.8% of Estonia's population can speak Russian. Command of Russian language, however, is rapidly decreasing among younger Estonians (primarily being replaced by the command of English). For example, if 53% of ethnic Estonians between 15 and 19 claim to speak some Russian, then among the 10- to 14-year-old group, command of Russian has fallen to 19% (which is about one-third the percentage of those who claim to have command of English in the same age group).
What is the answer to this question: How much of Estonia is ethnic Russians?
****
So... 25.5%

Article: Hydrogen was liquefied for the first time by James Dewar in 1898 by using regenerative cooling and his invention, the vacuum flask. He produced solid hydrogen the next year. Deuterium was discovered in December 1931 by Harold Urey, and tritium was prepared in 1934 by Ernest Rutherford, Mark Oliphant, and Paul Harteck. Heavy water, which consists of deuterium in the place of regular hydrogen, was discovered by Urey's group in 1932. Francois Isaac de Rivaz built the first de Rivaz engine, an internal combustion engine powered by a mixture of hydrogen and oxygen in 1806. Edward Daniel Clarke invented the hydrogen gas blowpipe in 1819. The Dobereiner's lamp and limelight were invented in 1823.

Question: Who was the first to discover deuterium?
Ans:
Harold Urey