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The Arecibo Message

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Let's say you're a human with a big radio transmitter, who wants to send a message to the putative aliens out there light-years away, listening by their radio receivers. What would your message say? How would you format it, since you don't have any concept of the recipient's language or cognitive abilities? What would be most interesting and salient to a completely unknown civilization? Given the limits of the exercise, there are only a few known factors about the recipient: you can assume that the recipient is technologically advanced enough to have built a radio, received the message, and recognized that it's actually a message rather than noise. But aside from that, a world of questions surround the issue.

Carl Sagan dramatized this problem (in reverse) in his 1985 book Contact. His novel was likely based on his own experience more than ten years earlier, he was faced with the challenge in real life. In 1974, astrophysicist Frank Drake proposed sending just such a message -- and Sagan was recruited to help write and format it.

Drake, Sagan, and others developed a message to be broadcast by the Arecibo radio telescope, using a mathematical scheme they hoped could be decoded by an alien civilization. The message itself consisted of just 1,679 binary digits (1's and 0's). The digits were broadcast one per second, on November 16, 1974. The telescope was pointed at the M13 cluster, some 25,000 light years away. The broadcast was never repeated -- hopefully someone will be listening when the message arrives in deep space (for what it's worth, by the time 25,000 years pass, M13 will no longer be where it was when we sent the message -- so our transmission will miss whoever lives there). But let's get back to brass tacks -- what did the message say? Well, using binary encoding, the message carried the information below. (A colorized version of the message, rendered as blocks, is also presented at left.)

  1. the numbers one (1) through ten (10)
  2. the atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
  3. the formulas for the sugars and bases in the nucleotides of DNA
  4. the number of nucleotides in DNA, and a graphic of the double helix structure of DNA
  5. a graphic figure of a man, the dimension (physical height) of an average man, and the human population of Earth
  6. a graphic of Earth's solar system
  7. a graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish

It's clear that the transmission was more a symbolic event than an actual attempt at communication -- if we were attempting to communicate, we'd probably send the message more than once, or to more than one spot in the sky. (A 1999 press release said as much, with Cornell Professor Donald Campbell explaining, "It was strictly a symbolic event, to show that we could do it.") But the possibility remains that some intelligence could intercept the message and perhaps decode it -- and maybe, just maybe, reply. In August of 2001, a crop circle appeared in farmland near the Chibolton radio telescope in Hampshire, UK. Known to crop circle aficionados as the Arecibo reply, the pattern looked like a modified version of the original transmission, showing a big-headed alien and adding silicon to the list of elements, among other changes. While it's clearly a hoax, it's a clever one, and took a lot of work to put together.

Further reading: the Arecibo message at Wikipedia, a mathematical explanation of the message, and more on Frank Drake.

So let's hear it: if you were sending a message into the unknown depths of space, what would you say?

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Words
15 Subatomic Word Origins
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In July 2017, researchers at the European Organization for Nuclear Research (CERN) found evidence for a new fundamental particle of the universe: Ξcc++, a special kind of Xi baryon that may help scientists better understand how quarks are held together. Is that Greek to you? Well, it should be. The names for many of the particles that make up the universe—as well as a few that are still purely theoretical—come from ancient Greek. Here’s a look at 15 subatomic etymologies.

1. ION

An ion is any atom or molecule with an overall electric charge. English polymath William Whewell suggested the name in an 1834 letter to Michael Faraday, who made major discoveries in electromagnetism. Whewell based ion on the ancient Greek verb for “go” (ienai), as ions move towards opposite charges. Faraday and Whewell had previously considered zetode and stechion.

2. ELECTRON

George Stoney, an Anglo-Irish physicist, introduced the term electron in 1891 as a word for the fundamental unit of charge carried by an ion. It was later applied to the negative, nucleus-orbiting particle discovered by J. J. Thomson in 1897. Electron nabs the -on from ion, kicking off the convention of using -on as an ending for all particles, and fuses it with electric. Electric, in turn, comes from the Greek for “amber,” in which the property was first observed. Earlier in the 19th century, electron was the name for an alloy of gold and silver.

3. PROTON

The electron’s counterpart, the positively charged proton in the nuclei of all atoms, was named by its discoverer, Ernest Rutherford. He suggested either prouton or proton in honor of William Prout, a 19th-century chemist. Prout speculated that hydrogen was a part of all other elements and called its atom protyle, a Greek coinage joining protos ("first") and hule ("timber" or "material") [PDF]. Though the word had been previously used in biology and astronomy, the scientific community went with proton.

4. NEUTRON

Joining the proton in the nucleus is the neutron, which is neither positive nor negative: It’s neutral, from the Latin neuter, “neither.” Rutherford used neutron in 1921 when he hypothesized the particle, which James Chadwick didn’t confirm until 1932. American chemist William Harkins independently used neutron in 1921 for a hydrogen atom and a proton-electron pair. Harkins’s latter application calls up the oldest instance of neutron, William Sutherland’s 1899 name for a hypothetical combination of a hydrogen nucleus and an electron.

5. QUARK

Protons and neutrons are composed of yet tinier particles called quarks. For their distinctive name, American physicist Murray Gell-Mann was inspired in 1963 by a line from James Joyce’s Finnegan’s Wake: “Three quarks for Muster Mark.” Originally, Gell-Mann thought there were three types of quarks. We now know, though, there are six, which go by names that are just as colorful: up, down, charm, strange, top, and bottom.

6. MESON

Made up of a quark and an antiquark, which has identical mass but opposite charge, the meson is a short-lived particle whose mass is between that of a proton and an electron. Due to this intermediate size, the meson is named for the ancient Greek mesos, “middle.” Indian physicist Homi Bhabha suggested meson in 1939 instead of its original name, mesotron: “It is felt that the ‘tr’ in this word is redundant, since it does not belong to the Greek root ‘meso’ for middle; the ‘tr’ in neutron and electron belong, of course, to the roots ‘neutr’ and ‘electra’.”

7., 8., AND 9. BOSON, PHOTON, AND GLUON

Mesons are a kind of boson, named by English physicist Paul Dirac in 1947 for another Indian physicist, Satyendra Nath Bose, who first theorized them. Bosons demonstrate a particular type of spin, or intrinsic angular momentum, and carry fundamental forces. The photon (1926, from the ancient Greek for “light”) carries the electromagnetic force, for instance, while the gluon carries the so-called strong force. The strong force holds quarks together, acting like a glue, hence gluon.

10. HADRON

In 2012, CERN’s Large Hadron Collider (LHC) discovered a very important kind of boson: the Higgs boson, which generates mass. The hadrons the LHC smashes together at super-high speeds refer to a class of particles, including mesons, that are held together by the strong force. Russian physicist Lev Okun alluded to this strength by naming the particles after the ancient Greek hadros, “large” or “bulky,” in 1962.

11. LEPTON

Hadrons are opposite, in both makeup and etymology, to leptons. These have extremely tiny masses and don’t interact via the strong force, hence their root in the ancient Greek leptos, “small” or “slender.” The name was first suggested by the Danish chemist Christian Møller and Dutch-American physicist Abraham Pais in the late 1940s. Electrons are classified as leptons.

12. BARYON

Another subtype of hadron is the baryon, which also bears the stamp of Abraham Pais. Baryons, which include the more familiar protons and neutrons, are far more massive, relatively speaking, than the likes of leptons. On account of their mass, Pais put forth the name baryon in 1953, based on the ancient Greek barys, “heavy” [PDF].

13. AXION

Quirky Murray Gell-Mann isn't the only brain with a sense of humor. In his 2004 Nobel Prize lecture, American physicist Frank Wilczek said he named a “very light, very weakly interacting” hypothetical particle the axion back in 1978 “after a laundry detergent [brand], since they clean up a problem with an axial current” [PDF].

14. TACHYON

In ancient Greek, takhys meant “swift,” a fitting name for the tachyon, which American physicist Gerald Feinberg concocted in 1967 for a hypothetical particle that can travel faster than the speed of light. Not so fast, though, say most physicists, as the tachyon would break the fundamental laws of physics as we know them.

15. CHAMELEON

In 2003, the American physicist Justin Khoury and South African-American theoretical physicist Amanda Weltman hypothesized that the elusive dark energy may come in the form of a particle, which they cleverly called the chameleon. Just as chameleons can change color to suit their surroundings, so the physical characteristics of the chameleon particle change “depending on its environment,” explains Symmetry, the online magazine dedicated to particle physics. Chameleon itself derives from the ancient Greek khamaileon, literally “on-the-ground lion.”

For more particle names, see Symmetry’s “A Brief Etymology of Particle Physics,” which helped provide some of the information in this list.

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Space
Look Up! The Orionid Meteor Shower Peaks This Weekend
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October is always a great month for skywatching. If you missed the Draconids, the first meteor shower of the month, don't despair: the Orionids peak this weekend. It should be an especially stunning show this year, as the Moon will offer virtually no interference. If you've ever wanted to get into skywatching, this is your chance.

The Orionids is the second of two meteor showers caused by the debris field left by the comet Halley. (The other is the Eta Aquarids, which appear in May.) The showers are named for the constellation Orion, from which they seem to originate.

All the stars are lining up (so to speak) for this show. First, it's on the weekend, which means you can stay up late without feeling the burn at work the next day. Tonight, October 20, you'll be able to spot many meteors, and the shower peaks just after midnight tomorrow, October 21, leading into Sunday morning. Make a late-night picnic of the occasion, because it takes about an hour for your eyes to adjust to the darkness. Bring a blanket and a bottle of wine, lay out and take in the open skies, and let nature do the rest.

Second, the Moon, which was new only yesterday, is but a sliver in the evening sky, lacking the wattage to wash out the sky or conceal the faintest of meteors. If your skies are clear and light pollution low, this year you should be able to catch about 20 meteors an hour, which isn't a bad way to spend a date night.

If clouds interfere with your Orionids experience, don't fret. There will be two more meteor showers in November and the greatest of them all in December: the Geminids.

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