World Book Trivia Challenge Advanced--12/31--time

Atoms of a radioactive element decay (break down) into atoms of another element. Because this decay occurs at a known rate, scientists can sometimes determine how old a sample is by measuring the amount of radioactive material it contains.
For example, some of the carbon in living things is a radioactive isotope (form) called carbon-14. Carbon-14 decays into nitrogen at a known rate, but living things constantly replenish the carbon 14 in their bodies. When an organism dies, it stops taking in new carbon-14. Thus, by analyzing the amount of carbon-14 left in a sample, scientists can often estimate how long ago an organism

Coordinated Universal Time, abbreviated UTC, serves as the standard international time. By definition, UTC is the time at the prime meridian as measured by atomic clocks. Other time zones derive their time by adding or subtracting a whole number of hours to UTC.

In the early 1900’s, the German-born physicist Albert Einstein developed a new branch of physics called relativity theory. His work revised many basic ideas about time. Perhaps most importantly, relativity theory holds that space and time are not fundamentally separate features of reality. Relativity theory overturned Newton’s assumptions.

We tend to believe that we can change the future but not the past. This distinction is sometimes called the arrow of change.

Using noon as the midpoint of the day gives us the letters a.m., meaning ante (before) meridiem, or before noon; p.m. means post (after) meridiem, or after noon.

Minute is a unit that is used to measure both time and angles. In time, 60 minutes make up one hour. Each minute is divided into 60 seconds. Because an hour is 1/24 of a day, a minute is 1/1,440 of a day. In measuring angles, 60 minutes make up one degree. A circle is divided into 360 degrees, and so one minute is 1/21,600 of a circle. Each minute of an angle is divided into 60 seconds.

The use of the day as a basic unit of time gave rise to two slightly different systems of timekeeping. These systems are: (1) solar time and (2) sidereal time.

The United Kingom, for example, went on daylight time or what it calls "Summer Time" during World War I (1914-1918). The United States adopted the plan in 1918 but repealed it in 1919. The United States also observed it from Feb. 9, 1942, to Sept. 30, 1945, due to World War II

The water clock, used as early as 3,500 years ago, consisted of a container that water flowed into or out of at a steady rate. People measured time by comparing the changing water level to marks on the container. Simpler clocks for everyday use included candles marked at regular lengths and oil lamps with marked reservoirs. As the candle burned down or the oil burned away, the marks indicated how much time had passed. Most of these clocks probably remained accurate only to about half an hour per day at best.

The phrase time capsule first described a container buried by the Westinghouse company in 1938 at the New York World's Fair. It was scheduled to be opened in 6939. The phrase may also refer to an object or archaeological site that vividly represents the past