Demon and Dæmon

St. Anthony plagued by demons, engraving by Martin Schongauer in the 1480s.

The word "demon" has a variety of usages. Typically, it refers to an evil spirit, devil or fiend.

It can refer to an evil passion or influence - demon alcohol or drugs.

It can be a very human person who is considered extremely wicked, evil, or cruel. It can also be more positively used to describe a person with great energy or drive - "He's a demon when it comes to his work."

In classical mythology, a daemon was a god, though a subordinate deity. It would be associated with a place or be a person's attendant spirit.

Leonardo da Vinci's Lady with an Ermine was
one source of inspiration for Pullman's "dæmon" concept.

I encountered the word dæmon as a being in the Philip Pullman's fantasy trilogy His Dark Materials. where they are external physical manifestations of a person's 'inner-self' that takes the form of an animal. These dæmons are not evil but essential.

Still, our modern usage of demon (from Greek daimónion) is usually a supernatural and often malevolent being prevalent in religion, occultism, literature, fiction, mythology and folklore, even though that original Greek word did not carry the negative connotation.

The word took on religious meanings. In Ancient Near Eastern religions as well as in the Abrahamic traditions, including ancient and medieval Christian demonology, a demon is considered an unclean spirit, a fallen angel, or a spirit of unknown type which may cause demonic possession. This is where the need for a cleansing exorcism originated.

Returning to the Greek conception, we find it in the works of Plato, where it describes the divine inspiration of Socrates. T

In usage, we distinguish the classical Greek "good" concept by using the anglicized daemon or daimon. The later Christian interpretation is demon.

The female demon Lilith appearing as a snake cavorting with herself
as personified within the Garden of Eden by John Collier, 1892

Halt and Catch Fire

Halt and Catch Fire is an American drama television series about a fictionalized version of the history of the personal computer revolution of the 1980s and then the growth of the World Wide Web in the early 1990s.

The show's title refers to a computer machine code instruction abbreviated as HCF. Halt and Catch Fire refers to a computer machine code instruction that causes the computer's central processing unit (CPU) to cease any meaningful operation to the point of requiring a restart of the computer.

Originally it referred to a fictitious instruction in IBM System/360 computers. Later, the joke became real when developers actually wrote such code.

Usually, when a computer hits a bug in the code it probably can still recover, but an HCF instruction is one where there is no way for the system to recover without a restart. It halts the computer, but the "catch fire" part is not literal. There is no computer bursting into flames. The exaggeration was that the circuits would be switching so fast that they would overheat and burn.

Measuring Energy

One of the biggest honors a scientist can receive is to have his or her name attached to their invention or discovery. These new words are known as eponyms, and here are some eponyms we have for the measurement of energy.

James Prescott Joule (1818–1889) gave us the joule, a unit that measures work, or energy (a force acting over distance. He was a British physicist who established that all forms of energy are equivalent.

Joule also developed thermodynamics, along with Lord Kelvin who is better known because absolute temperatures are stated in units of kelvin in his honor. While the existence of a lower limit to temperature (absolute zero) was known prior to his work, Lord Kelvin is widely known for determining its correct value as approximately −273.15 degree Celsius or −459.67 degree Fahrenheit.

Our common energy measurement of volts comes from Alessandro Volta (1745–1827). This unit measures differences in electrical potential. The Italian physicist Volta also discovered methane and  used his tongue to detect electricity and invented the first electric battery.

Another major electrical unit, the current-measuring ampere, takes its name from French physicist André-Marie Ampère (1775–1836) who was one of the main founders of the science of electromagnetism, which he called “electrodynamics.”