Information Theory
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What is Information Theory?
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Prehistory: Proto-writing
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Ptolemaic: Rosetta Stone
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Ancient History: The Alphabet
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Source Encoding
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Visual Telegraphs (case study)
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Decision Tree Exploration
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Electrostatic Telegraphs (case study)
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The Battery & Electromagnetism
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Morse Code & The Information Age
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Morse code Exploration
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Symbol Rate
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Symbol Rate Exploration
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Introduction to Channel Capacity
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Message Space Exploration
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What's Next?
Ancient History: The Alphabet History of the Alphabet. This video introduces the Hieroglyphic, Cuneiform, Hieratic, Demotic & Phoenician writing systems.
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- Informally we can think of information as some message
- stored or transmitted using some medium.
- When you paint, you are representing
- your message using a continuous pattern,
- with a seemingly endless numbers of possible forms.
- You are free to express yourself.
- When humans began developing writing systems,
- we naturally had to divide our world into a finite
- number of atomic units which we express using symbols.
- Now any written language can be thought of in this way
- Messages are formed by arranging
- symbols in specific patterns
- Lets return to 3000 B.C and explore
- two ancient writing systems.
- First, in ancient Egypt we had hieroglyphics –
- A priestly form of communication reserved for
- governmental, fiscal, magical and religious purposes.
- It was practised by a select few writers, known as scribes,
- and writing was generally unintelligible to the common people.
- The symbols themselves broadly fall into two categories:
- word signs, which are symbols that represent
- a single meaningful concept and sound signs.
- These symbols represent chunks of sound.
- Now the total number of different symbols in common use
- was over 1,500.
- And if you divide all of these symbols into word signs
- versus sound signs, we find a much smaller portion
- of sound signs.
- There are around 140 sound signs and of these,
- only 33 represented distinct consonants.
- A tiny fraction of all the symbols in use.
- At the time the medium used
- to store the symbols was primarily rock.
- And this was ideal for durable inscriptions
- allowing messages to travel into the future.
- Mobility was not a main concern
- when communicating messages in this way.
- However a new physical medium for storing symbols
- was emerging at the time.
- Along the Nile, silk deposits, left from flooding,
- made the surrounding land extremely fertile.
- And one of the many crops they grew was papyrus.
- It could be sliced into strips
- and formed an almost weightless tablet
- And these strips were then soaked and woven together.
- and finally pressed,
- allowing the natural sugars to act as glue.
- After several days, it dried and formed
- an almost weightless tablet.
- This medium was ideal for sending messages
- across greater spaces rather than the more
- durable inscriptions focused on time.
- Now this shift towards cheap,
- portable mediums for storing symbols
- coincided with the spread of writing
- into the hands of more people for new purposes.
- Gradually, as people began to write more on papyrus,
- the symbols evolved to suit more rapid writing.
- This led to a cursive script known as "Hieratic"
- For example here is the world's oldest surviving
- surgical document.
- It's written in heiratic script dated to around 1600 B.C.
- Now these symbols were based on hieroglyphics.
- however the pictures were simplified to match
- the swiftness of writing.
- An ancient shorthand
- Also the number of common symbols
- in use began to shrink, down to around 700.
- By escaping from the heavy medium of stone,
- thought gained lightness.
- A marked increase in writing by hand
- was accompanied by the secularization of writing,
- thought and activity.
- This led to a new writing system called "Demotic".
- Around 650 B.C which was devised specifically to
- facilitate the ease of rapid writing.
- For example this text is known as
- a marriage contract and is one of the
- earliest known examples of demotic script.
- It's interesting to notice that there was
- a dramatic reduction again in the total number
- of symbols with this new system.
- Roughly 10% of the total number
- of symbols used before.
- This was due to a shift towards the use of phonetic symbols,
- or sound signs, over word symbols or meaning signs.
- And the new simplicity meant that
- children could be taught to write at a young age.
- We see this same pattern in other cultures.
- Let's return back to 3000 B.C
- and visit Mesopotamia
- where "cuneiform" was the writing system
- originally used for fiscal purposes
- as it was a powerful method of tracking debt
- and surplus commodities before the invention of coins.
- For example here is a document recording
- someone's stock of animal hides
- and this type of writing evolved to suit other needs,
- for example this tablet contains a recipe
- for bread and beer.
- And here's another tablet which contains a legal document.
- Now originally the writing system was used by the
- Sumerians and there are over 2,000 different symbols in use which could also be divided into word signs
- and sound signs. Akkadian gradually replaced Sumarian as the spoken language and here is the earliest
- known dictionary from 2300 B.C. It contains word lists in Sumerian and Akkadian.
- And this was discovered in modern Syria. When it was adapted by the Akkadians and fitted to their language
- they reduced the number of symbols to around 600. And they did this again by moving towards sound signs.
- Again we see both hieroglyphics and cuneiform using several hundred sound symbols in their more evolved forms.
- And as writing systems escaped their formal usage and spread to more and more people, the soil was ripe for
- the invention of a brand new writing system for the people
- One of the great discoveries in the history of writing, is dated to around 1700 B.C
- The Sinai inscriptions were found in the Sinai Peninsula and there were about 20 ft apart.
- This was important because each picture denotes a consonant sound and no word signs are used
- When sounded out correctly, the letters would produce words in ancient Semitic
- Although not fully deciphered, this message appears to be of the form: name, rank, prayer.
- The two words deciphered are "Chief" and "God".
- This innocent example was part of a writing revolution creating meaning by merging sound signs only
- By 1000 B.C, we arrive at the Phoenician alphabet, which emerges along the Mediterranean used by the Phoenicians
- who are a maritime trading culture. The Phoenician writing system was based on the principle that one sign
- represents one consonant and it was used to write a northern Semitic language containing only 22 symbols
- total. These symbols chosen to represent these sounds were often borrowed from hieroglyphic pictures so that
- the letter's name began with the letter sound. For example, "Mem" which stood for the water, became what we know of
- as the letter "M". "Alph" which stood for ox, became what we know of as the letter A
- But the secret power of this alphabet, unknown to its inventors, was that it did not need Semitic speech
- in order to work.
- With modest adjustments these miraculous letters would be fitted to diverse tongues of Europe, India and
- South East Asia. Carrying literacy around the globe.
- This was the source of the Greek and later Roman alphabet forms we know today.
- The idea of an alphabet is a powerful method for transmitting and storing information
- Realize it doesn't really matter what the symbols are or how you choose them or even what language it is in
- Information is just a selection from a collection of possible symbols
- And over time we've always looked for faster, more efficient ways of transporting information across greater
- and greater spaces. When we try doing this using new mediums which travel faster than any human
- or animal, an engineering problem presents itself.
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At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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