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Concepts

59 concepts

The ideas the research turns on, defined in the site's own words, with every answer and method that uses them.

Any field

All A B C D E F G H IJK L M N O PQR S T U VWXYZ#

A 6

AbjadAn alphabet that writes consonants only and leaves vowels to the reader.

AcrophonyGiving a picture-sign the sound value of the first sound of the word for what it depicts.

AirburstA meteor exploding in the air before reaching the ground.

Ancient DNAGenetic material recovered from old remains, read to tell who someone was and who they were related to.

ArchaeoastronomyTesting whether a monument was aligned on the sky, and how.

Archaeological forgeryAn object made or altered in modern times and presented as an ancient find, usually by planting it in the ground or in a collection.

B 4

Ball lightningA reported luminous sphere that floats for seconds during thunderstorms, not yet reproduced in the laboratory.

BathymetryThe measured shape and depth of the sea floor.

Bilingual textThe same text in two scripts or languages, the standard key to an unread one.

BoustrophedonWriting in which the direction alternates line by line, right to left then left to right, often with the letters mirrored on the reversed li

C 5

Calibration curveThe correction that turns a radiocarbon measurement into a calendar date.

Chain of custodyThe record of who held a piece of evidence, and when, from its finding to now.

CodicologyThe study of a book as an object: its parchment, quires, binding and marks of use.

Combinatory methodWorking out what words in an unknown language mean from where they occur, what they occur with and how their endings change across many text

CribA piece of plaintext known or guessed to sit at a particular place in a cipher text.

D 5

DeciphermentWorking out how an unread script records a language, so that its texts can be read.

DendrochronologyDating wood by matching the pattern of its growth rings to a known sequence.

Dispersion measureThe delay of a radio burst's low frequencies, which tells how much plasma it crossed.

Drift modellingWorking back from where debris washed up to where it entered the water.

Dyson sphereA hypothetical structure built around a star to capture its energy.

E 3

Electrical resistivity tomographyImaging the ground by how it resists an electric current between electrodes.

EntropyA measure of how unpredictable a text's next sign is, given what came before.

Eyewitness testimonyWhat people say they saw, and what is known about how well that matches what happened.

F 1

Frequency analysisReading a cipher by counting how often each sign appears and matching the counts to a language.

G 2

Gromark cipherA cipher that shifts each letter by a running numeric key made from a short seed.

Ground-penetrating radarMapping what lies under the ground by bouncing radio pulses off buried surfaces.

H 2

Held-out testChecking a reading or model on data that was not used to build it.

Homophonic substitutionA cipher in which one plaintext letter can be written as any of several cipher signs.

I 1

Impact hypothesisThe proposal that a comet or asteroid strike caused a past event on Earth.

K 1

Keyed alphabetA cipher alphabet that starts with a key word and continues with the letters not yet used.

L 3

Language isolateA language with no demonstrated relative, so its words and grammar cannot be worked out by comparison with a known family.

Light curveA star's brightness plotted against time.

Logographic scriptA writing system whose signs stand for words or morphemes.

M 1

Multispectral imagingPhotographing a surface in many bands of light to bring out what the eye cannot see.

N 4

Narrowband signalA radio signal confined to a very small range of frequencies, which nature rarely makes.

NomenclatorA cipher that pairs a substitution alphabet with a list of code groups for whole words and names.

Non-gravitational accelerationA push on a body in orbit that gravity alone does not account for.

Null modelWhat the data would look like if nothing were going on, used to judge whether something is.

O 1

OutgassingGas escaping from a body as it warms, which can push it and make a tail.

P 3

PalaeographyDating and placing a manuscript by the forms of its letters and the habits of its scribes.

PlasmaGas hot or charged enough that its atoms have come apart into ions and electrons.

Proto-writingA sign system that records information without recording the sounds or words of a language.

R 3

Radiocarbon datingDating organic material by how much of its carbon-14 has decayed.

Rebus principleUsing the sign for one thing to write a different word that sounds the same.

Running-key cipherA polyalphabetic cipher whose key is a long text rather than a repeating word.

S 4

Side-scan sonarMapping the sea floor by sweeping it with sound from a towed instrument.

SteganographyHiding a message so that nobody knows there is one, as distinct from making it unreadable.

StratigraphyReading the order of events from the order of the layers in the ground.

SyllabaryA writing system whose signs stand for syllables rather than single sounds.

T 5

TablatureNotation that says which strings or finger positions to play, not which pitches sound.

TechnosignatureAny observable sign of technology beyond Earth.

Thermoluminescence datingDating fired clay or burnt stone by the light it stores since it was last heated.

Transit photometryFinding and measuring things that pass in front of a star by the dip in its light.

Transposition cipherA cipher that keeps the plaintext's letters and changes their order.

U 1

UD.GAL.NUN orthographyA spelling system in Early Dynastic Sumerian literary tablets that replaces common signs by others according to rules, named after three of

V 2

Vigenère cipherA substitution cipher that shifts each letter by a key word's letters in turn.

Virtual unwrappingReading a rolled or damaged scroll from a CT scan without opening it.

X 1

X-ray fluorescenceTelling what elements a surface contains from the X-rays it gives off when illuminated.

Z 1

Zipf's lawIn natural text, a word's frequency falls off in proportion to its rank.