The field of physics has expanded exponentially in the last few centuries, but scientists still grapple with a number of problems and questions that remain unsolved. Several of these problems are theoretical: they involve observed phenomena that existing theories seem incapable of explaining. Others are experimental: they concern theories that do not lend themselves to testing or phenomena that cannot be investigated in greater detail. What are several of the most prominent unsolved problems?
Back in the day
Masada is an ancient mountaintop fortress in Israel's Judaean Desert. In 66 CE, with the outbreak of the Jewish war against Rome, the Zealots, an extremist Jewish sect, seized the fortress in a surprise attack and massacred its Roman garrison. After the fall of Jerusalem, Masada, the last remnant of Jewish rule, refused to surrender. Masada remained under Zealot control until 73 CE, when, after months of siege, the Romans finally breached the walls. What did they discover when they entered?
Born on a day like today
Recognized as the most famous female painter of the 18th century, Élisabeth-Louise Vigée-Lebrun began painting portraits professionally in her early teens, ultimately becoming one of the most technically fluent portraitists of her era. In 1779, she was summoned to Versailles to paint Marie-Antoinette, whom she would paint at least 25 more times. At the outbreak of the French Revolution, she left France and traveled abroad. Which notable figures did she paint during her travels?