Lists and Stories

How Does the Electoral College Work? American voters go to the polls on the Tuesday following the first Monday in November, but the ballots that they cast do not directly elect the president. Instead, the will of the voters is reflected in the actions of state electors. These electors are selected by political parties at the state...
How Does the Human Body Maintain Its Temperature? People are mammals, and mammals are warm-blooded creatures, capable of maintaining a relatively constant internal temperature regardless of the environmental temperature. Body temperature control is one example of homeostasis—an organism’s self-regulating process that tends to maintain internal...
How Does the Olympic Torch Stay Lit? In 2000 the Olympic torch spent three minutes submerged in the Coral Sea. In 2008 climbers carried it to the summit of Mount Everest. In 2016 in Brazil the torch took a ride on a surfboard. In none of those occasions did its flame go out. But how? To find out, we have to go back to the tradition’s...
How Does the U.S. Government Define the Difference Between a Protest and a Riot? Generally speaking, a protest in the sense relevant here is “a usually organized public demonstration of disapproval” (of some law, policy, idea, or state of affairs), while a riot is “a disturbance of the peace created by an assemblage of usually three or more people acting with a common purpose...
How Does Wi-Fi Work? Wi-Fi has become an integral part of our fast-paced everyday lives. Thanks to Wi-Fi, we no longer have to be tethered to the Internet with cables. But have you ever stopped to wonder how it works? Wi-Fi uses radio waves to transmit information between your device and a router via frequencies. Two...
How Fast Is the Universe Expanding? The rate at which the universe is expanding is called the Hubble constant, named after astronomer Edwin Hubble, who, with Milton Humason, showed convincingly that the velocity with which a galaxy was moving away from Earth was proportional to its distance. That is, velocity = Hubble constant ×...
How Fast Is the World’s Fastest Human? In 2009 Jamaican sprinter Usain Bolt set the world record in the 100-meter sprint at 9.58 seconds. For those of us more accustomed to sitting than sprinting, to translate this feat into terms of speed is to simply underscore the stunning nature of Bolt’s performance. Speed is the rate at which an...
How Have Zoroastrians Been Treated in Muslim Iran? Zoroastrianism is one of the world’s oldest monotheistic religions. Founded in ancient Persia in the 6th century BCE, it gradually overtook local polytheistic faiths. Zoroastrianism was even practiced by Persia’s ruling families. Under the Sasanian empire, which was founded in 224 CE, it was the...
How Is a Vaccine Approved for Use? Vaccines play an essential role in disease prevention, helping minimize the spread of contagious illness and saving countless lives. Before vaccines ever gain widespread use in humans, however, they undergo years of research and development, with multiple rounds of clinical testing, to ensure that...
How Is BMI Calculated? BMI stands for “body mass index” and is an estimate of total body fat. BMI does not measure body fat directly, but it does help determine whether a person is clinically underweight or obese. The formula to calculate BMI is as follows: weight (kg) / [height (m)]2 = BMI For adults over age 20, a BMI...
How Is Coffee Decaffeinated? Coffee "beans" (they aren’t really beans) naturally contain caffeine. Although a jolt of caffeine is exactly what many people are looking for when they reach for a cup of joe, the beans can be processed to remove most of the stimulant, creating a drink that can be enjoyed at night without losing...
How Is Diving Scored? The Summer Olympic Games mean that the graceful sport of diving is once again in the international spotlight. The individual and synchronized events on the platform and springboard showcase the aerial talents of these athletes, although it can be hard to tell how some dives are better than others....
How Is Inflammation Involved in Swelling? Immediately following an injury, the traumatized area becomes red, warm, and painful, and it begins to swell. The swelling process, also known as edema, is the result of acute inflammation, a response triggered by damage to living tissues. In the case of injury, the purpose of the inflammatory...
$Refraction of light$

How Is Light Both a Particle and a Wave? The behavior of light cannot be explained solely by models of particles or solely by models of waves. If light is a particle, then why does it refract when travelling from one medium to another? And if light is a wave, then why does it dislodge electrons? But all behavior of light can be explained...
How Is Tennis Scored? To win a game in tennis, a player must win four points and must win by a margin of two. The scoring goes as follows, after starting at love: 15, 30, 40, game. This system is medieval in origin. It never has been satisfactorily explained why three points equal 40 rather than 45. Zero is generally...
How is the U.S. Unemployment Rate Calculated? This article was originally published on May 1, 2020. In general, the unemployment rate in the United States is obtained by dividing the number of unemployed persons by the number of persons in the labor force (employed or unemployed) and multiplying that figure by 100. There are, however, various...
How Long Did the Flu Pandemic of 1918 Last? The influenza pandemic of 1918–19, also called the Spanish flu, lasted between one and two years. Companion, Spanish Flu, 1918, pandemic, influenza, three waves The pandemic occurred in three waves, though not simultaneously around the globe. In the Northern Hemisphere, the first wave originated in...
How Long Is the Amazon River? The Amazon is undeniably one of the world’s greatest rivers. It is the largest river by volume, and its basin is home to the Amazon Rainforest, the world’s richest and most-varied biological reservoir. The Amazon might also be the world’s longest river—depending on whom you ask. Most scientists...
How Many Countries Are There in the World? The United Nations includes 193 member countries and 2 recognized independent nations (Vatican City and Palestine). See a list of countries here, or visit our country portal here. Companion, countries, world countries, united nations, Britannica, Encyclopedia Britannica, Encyclopaedia...
How Many Electoral College Votes Does Each U.S. State Have? This infographic provides a list of the electoral college votes per state (including the District of Columbia), from most to least. The data are listed below. Spotlight, infographic, electoral college, United States, U.S. presidency, U.S. presidential election, votes,...