[Script Info] Title: [Events] Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text Dialogue: 0,0:00:04.53,0:00:08.53,Default,,0000,0000,0000,,The signal fire is no doubt one of the oldest technologies Dialogue: 0,0:00:08.53,0:00:10.66,Default,,0000,0000,0000,,for transmitting information – Dialogue: 0,0:00:10.66,0:00:14.51,Default,,0000,0000,0000,,perhaps dating back to the first controlled use of fire. Dialogue: 0,0:00:14.51,0:00:19.14,Default,,0000,0000,0000,,It allows one person to influence another's belief state – Dialogue: 0,0:00:19.14,0:00:21.12,Default,,0000,0000,0000,,across a distance. Dialogue: 0,0:00:21.12,0:00:22.78,Default,,0000,0000,0000,,Because with the ability to notice Dialogue: 0,0:00:22.78,0:00:25.76,Default,,0000,0000,0000,,either the presence or absence of something, Dialogue: 0,0:00:25.76,0:00:29.94,Default,,0000,0000,0000,,we are able to switch between one of two belief states. Dialogue: 0,0:00:29.94,0:00:32.72,Default,,0000,0000,0000,,One difference. Two states. Dialogue: 0,0:00:35.23,0:00:37.20,Default,,0000,0000,0000,,And ff we look back in history, Dialogue: 0,0:00:37.20,0:00:39.24,Default,,0000,0000,0000,,we find that this was of great importance Dialogue: 0,0:00:39.24,0:00:40.71,Default,,0000,0000,0000,,to military powers, Dialogue: 0,0:00:40.71,0:00:44.25,Default,,0000,0000,0000,,which all rely on effective communications. Dialogue: 0,0:00:44.25,0:00:45.38,Default,,0000,0000,0000,,And a great place to begin Dialogue: 0,0:00:45.38,0:00:47.80,Default,,0000,0000,0000,,is with the Greek myth of Cadmus – Dialogue: 0,0:00:47.80,0:00:50.04,Default,,0000,0000,0000,,a Phoenician prince who introduced Dialogue: 0,0:00:50.04,0:00:52.64,Default,,0000,0000,0000,,the 'phonetic' letters to Greece. Dialogue: 0,0:00:52.64,0:00:53.96,Default,,0000,0000,0000,,The Greek alphabet – Dialogue: 0,0:00:53.96,0:00:55.77,Default,,0000,0000,0000,,borrowed from the Phoenician letters – Dialogue: 0,0:00:55.77,0:00:58.47,Default,,0000,0000,0000,,along with light, and cheap, papyrus – Dialogue: 0,0:00:58.47,0:01:00.60,Default,,0000,0000,0000,,effected the transfer of power Dialogue: 0,0:01:00.60,0:01:03.98,Default,,0000,0000,0000,,from the priestly to the military class. Dialogue: 0,0:01:03.98,0:01:07.07,Default,,0000,0000,0000,,And Greek military history provides clear evidence Dialogue: 0,0:01:07.07,0:01:09.48,Default,,0000,0000,0000,,of the first advancements in communication, Dialogue: 0,0:01:09.48,0:01:12.46,Default,,0000,0000,0000,,stemming from the use of signal torches. Dialogue: 0,0:01:12.46,0:01:16.67,Default,,0000,0000,0000,,Polybius was a Greek historian born in 200 BC. Dialogue: 0,0:01:16.67,0:01:18.16,Default,,0000,0000,0000,,He wrote 'The Histories,' which is Dialogue: 0,0:01:18.16,0:01:19.90,Default,,0000,0000,0000,,a treasure trove of detail related to Dialogue: 0,0:01:19.90,0:01:23.02,Default,,0000,0000,0000,,the communication technologies of the time. Dialogue: 0,0:01:23.02,0:01:26.46,Default,,0000,0000,0000,,He writes: "The power of acting at the right time Dialogue: 0,0:01:26.46,0:01:30.39,Default,,0000,0000,0000,,contributes very much to the success of enterprises. Dialogue: 0,0:01:30.39,0:01:34.00,Default,,0000,0000,0000,,And fire signals are the most efficient of all devices Dialogue: 0,0:01:34.00,0:01:36.41,Default,,0000,0000,0000,,which aid us to do this." Dialogue: 0,0:01:36.41,0:01:40.47,Default,,0000,0000,0000,,However, the limitation of a signal fire was clear to him. Dialogue: 0,0:01:40.47,0:01:41.45,Default,,0000,0000,0000,,He writes: Dialogue: 0,0:01:41.45,0:01:43.82,Default,,0000,0000,0000,,"It was possible for those who had agreed on this Dialogue: 0,0:01:43.82,0:01:47.14,Default,,0000,0000,0000,,to convey information that, say, a fleet had arrived. Dialogue: 0,0:01:47.14,0:01:48.84,Default,,0000,0000,0000,,But when it came to some citizens Dialogue: 0,0:01:48.84,0:01:50.90,Default,,0000,0000,0000,,having been guilty of treachery, Dialogue: 0,0:01:50.90,0:01:53.56,Default,,0000,0000,0000,,or a massacre having taken place in town – Dialogue: 0,0:01:53.56,0:01:57.09,Default,,0000,0000,0000,,things that often happen, but cannot all be foreseen – Dialogue: 0,0:01:57.09,0:02:01.56,Default,,0000,0000,0000,,all such matters defied communication by fire signal." Dialogue: 0,0:02:01.56,0:02:03.28,Default,,0000,0000,0000,,A fire signal is great when Dialogue: 0,0:02:03.28,0:02:06.25,Default,,0000,0000,0000,,the space of possible messages is small – Dialogue: 0,0:02:06.25,0:02:11.45,Default,,0000,0000,0000,,such as enemy has arrived or not arrived. Dialogue: 0,0:02:11.45,0:02:13.65,Default,,0000,0000,0000,,However, when the message space – which is Dialogue: 0,0:02:13.65,0:02:17.10,Default,,0000,0000,0000,,the total number of possible messages – grows, Dialogue: 0,0:02:17.10,0:02:20.33,Default,,0000,0000,0000,,there was a need to communicate many differences. Dialogue: 0,0:02:20.33,0:02:23.17,Default,,0000,0000,0000,,And in The Histories, Polybius describes a technology Dialogue: 0,0:02:23.17,0:02:25.72,Default,,0000,0000,0000,,developed by Aeneas Tacticus – Dialogue: 0,0:02:25.72,0:02:28.48,Default,,0000,0000,0000,,one of the earliest Greek writers on the art of war – Dialogue: 0,0:02:28.48,0:02:31.13,Default,,0000,0000,0000,,from the 4th century BC. Dialogue: 0,0:02:31.13,0:02:33.100,Default,,0000,0000,0000,,And his technology was described as follows: Dialogue: 0,0:02:33.100,0:02:35.62,Default,,0000,0000,0000,,"Those who are about to communicate Dialogue: 0,0:02:35.62,0:02:38.31,Default,,0000,0000,0000,,urgent news to each other by fire signal Dialogue: 0,0:02:38.31,0:02:40.04,Default,,0000,0000,0000,,should procure two vessels Dialogue: 0,0:02:40.04,0:02:42.84,Default,,0000,0000,0000,,of exactly the same width and depth. Dialogue: 0,0:02:42.84,0:02:44.91,Default,,0000,0000,0000,,And through the middle should pass a rod, Dialogue: 0,0:02:44.91,0:02:47.88,Default,,0000,0000,0000,,graduated into equal sections – Dialogue: 0,0:02:47.88,0:02:50.49,Default,,0000,0000,0000,,each clearly marked off from the next, Dialogue: 0,0:02:50.49,0:02:52.17,Default,,0000,0000,0000,,denoted with a Greek letter." Dialogue: 0,0:02:52.17,0:02:53.90,Default,,0000,0000,0000,,Each letter would correspond to Dialogue: 0,0:02:53.90,0:02:56.52,Default,,0000,0000,0000,,a single message in a look-up table which contain Dialogue: 0,0:02:56.52,0:03:01.22,Default,,0000,0000,0000,,the most common events that occur in war. Dialogue: 0,0:03:01.22,0:03:04.12,Default,,0000,0000,0000,,To communicate, they would proceed as follows: Dialogue: 0,0:03:04.12,0:03:06.02,Default,,0000,0000,0000,,First, the sender would raise his torch Dialogue: 0,0:03:06.02,0:03:07.92,Default,,0000,0000,0000,,to signal he had a message. Dialogue: 0,0:03:07.92,0:03:09.94,Default,,0000,0000,0000,,The receiver would then raise his torch, Dialogue: 0,0:03:09.94,0:03:12.37,Default,,0000,0000,0000,,signaling he was ready to receive it. Dialogue: 0,0:03:12.37,0:03:15.65,Default,,0000,0000,0000,,Then, the sender would lower his torch, Dialogue: 0,0:03:15.65,0:03:18.36,Default,,0000,0000,0000,,and they would both begin to drain their vessels Dialogue: 0,0:03:18.36,0:03:22.54,Default,,0000,0000,0000,,from a bored hole of equal size at the bottom. Dialogue: 0,0:03:22.54,0:03:24.83,Default,,0000,0000,0000,,Now, when the event is reached, Dialogue: 0,0:03:24.83,0:03:26.88,Default,,0000,0000,0000,,the sender raises his torch Dialogue: 0,0:03:26.88,0:03:30.87,Default,,0000,0000,0000,,to signal that they should both stop the flow of water. Dialogue: 0,0:03:30.87,0:03:34.20,Default,,0000,0000,0000,,This results in equal water levels, Dialogue: 0,0:03:34.20,0:03:39.11,Default,,0000,0000,0000,,denoting a single shared message. Dialogue: 0,0:03:39.11,0:03:40.64,Default,,0000,0000,0000,,This ingenious method Dialogue: 0,0:03:40.64,0:03:44.92,Default,,0000,0000,0000,,used differences in time to signal messages. Dialogue: 0,0:03:44.92,0:03:48.43,Default,,0000,0000,0000,,However, its expressive capabilitiy was limited, Dialogue: 0,0:03:48.43,0:03:50.87,Default,,0000,0000,0000,,mainly due to its speed. Dialogue: 0,0:03:50.87,0:03:53.09,Default,,0000,0000,0000,,Polybius then writes of a newer method – Dialogue: 0,0:03:53.09,0:03:55.51,Default,,0000,0000,0000,,originally devised by Democritus – Dialogue: 0,0:03:55.51,0:03:58.74,Default,,0000,0000,0000,,which he claims was "perfected by myself, Dialogue: 0,0:03:58.74,0:04:01.41,Default,,0000,0000,0000,,and quite definite and capable of dispatching – Dialogue: 0,0:04:01.41,0:04:02.71,Default,,0000,0000,0000,,with accuracy – Dialogue: 0,0:04:02.71,0:04:04.92,Default,,0000,0000,0000,,every kind of urgent message." Dialogue: 0,0:04:04.92,0:04:07.34,Default,,0000,0000,0000,,His method – now known as the 'Polybius Square' – Dialogue: 0,0:04:07.34,0:04:08.90,Default,,0000,0000,0000,,works as follows: Dialogue: 0,0:04:08.90,0:04:11.04,Default,,0000,0000,0000,,Two people, seperated by a distance, Dialogue: 0,0:04:11.04,0:04:12.69,Default,,0000,0000,0000,,each have 10 torches – Dialogue: 0,0:04:12.69,0:04:15.21,Default,,0000,0000,0000,,separated into two groups of five. Dialogue: 0,0:04:15.21,0:04:17.29,Default,,0000,0000,0000,,To begin, the sender raises a torch Dialogue: 0,0:04:17.29,0:04:20.06,Default,,0000,0000,0000,,and waits for the receiver to respond. Dialogue: 0,0:04:20.06,0:04:22.52,Default,,0000,0000,0000,,Then, the sender lights a certain number Dialogue: 0,0:04:22.52,0:04:26.27,Default,,0000,0000,0000,,from each group of torches – and raises them. Dialogue: 0,0:04:31.73,0:04:32.89,Default,,0000,0000,0000,,The receiver then counts Dialogue: 0,0:04:32.89,0:04:36.51,Default,,0000,0000,0000,,the number of torches lit in the first group. Dialogue: 0,0:04:36.51,0:04:39.15,Default,,0000,0000,0000,,This number defines the row position Dialogue: 0,0:04:39.15,0:04:41.91,Default,,0000,0000,0000,,in an alphabetic grid they share. Dialogue: 0,0:04:41.91,0:04:43.86,Default,,0000,0000,0000,,And the second group of torches Dialogue: 0,0:04:43.86,0:04:47.33,Default,,0000,0000,0000,,signifies the column position in this grid. Dialogue: 0,0:04:47.33,0:04:50.09,Default,,0000,0000,0000,,The intersection of the row and column number Dialogue: 0,0:04:50.09,0:04:52.33,Default,,0000,0000,0000,,defines the letter sent. Dialogue: 0,0:04:52.33,0:04:54.10,Default,,0000,0000,0000,,Realize, this method can be thought of Dialogue: 0,0:04:54.10,0:04:56.73,Default,,0000,0000,0000,,as the exchange of two symbols. Dialogue: 0,0:04:56.73,0:05:00.22,Default,,0000,0000,0000,,Each group of five torches is a symbol, Dialogue: 0,0:05:00.22,0:05:02.83,Default,,0000,0000,0000,,which was limited to five differences – Dialogue: 0,0:05:02.83,0:05:05.33,Default,,0000,0000,0000,,from one to five torches. Dialogue: 0,0:05:05.33,0:05:07.64,Default,,0000,0000,0000,,Together, these two symbols multiply Dialogue: 0,0:05:07.64,0:05:12.51,Default,,0000,0000,0000,,to give 5 x 5 = 25 differences – Dialogue: 0,0:05:12.51,0:05:15.14,Default,,0000,0000,0000,,not 5 + 5. Dialogue: 0,0:05:15.14,0:05:17.27,Default,,0000,0000,0000,,This multiplication demonstrates Dialogue: 0,0:05:17.27,0:05:21.42,Default,,0000,0000,0000,,an important combinatorial understanding in our story. Dialogue: 0,0:05:21.42,0:05:25.07,Default,,0000,0000,0000,,It was explained clearly in a 6th-century-BC Dialogue: 0,0:05:25.07,0:05:28.71,Default,,0000,0000,0000,,Indian medical text, attributed to Sushruta – Dialogue: 0,0:05:28.71,0:05:32.39,Default,,0000,0000,0000,,an ancient Indian sage – as follows: Dialogue: 0,0:05:32.39,0:05:34.62,Default,,0000,0000,0000,,"Given 6 different spices, Dialogue: 0,0:05:34.62,0:05:38.17,Default,,0000,0000,0000,,how many possible different tastes can you make?" Dialogue: 0,0:05:38.17,0:05:41.06,Default,,0000,0000,0000,,Well, the process of making a mixture Dialogue: 0,0:05:41.06,0:05:44.38,Default,,0000,0000,0000,,can be broken down into in six questions: Dialogue: 0,0:05:44.38,0:05:46.96,Default,,0000,0000,0000,,Do you add A? Yes or no? Dialogue: 0,0:05:46.96,0:05:48.88,Default,,0000,0000,0000,,Do you add B? Dialogue: 0,0:05:48.88,0:05:50.06,Default,,0000,0000,0000,,C? Dialogue: 0,0:05:50.06,0:05:51.14,Default,,0000,0000,0000,,D? Dialogue: 0,0:05:51.14,0:05:52.18,Default,,0000,0000,0000,,E? Dialogue: 0,0:05:52.18,0:05:53.51,Default,,0000,0000,0000,,and F? Dialogue: 0,0:05:53.51,0:05:55.90,Default,,0000,0000,0000,,Realize, this multiplies into Dialogue: 0,0:05:55.90,0:05:59.32,Default,,0000,0000,0000,,a tree of possible answer sequences – Dialogue: 0,0:05:59.32,0:06:05.07,Default,,0000,0000,0000,,2 x 2 x 2 x 2 x 2 x 2 = 64 ... Dialogue: 0,0:06:05.07,0:06:07.90,Default,,0000,0000,0000,,64 different sequences of answers Dialogue: 0,0:06:07.90,0:06:10.76,Default,,0000,0000,0000,,are therefore possible. Dialogue: 0,0:06:10.76,0:06:14.54,Default,,0000,0000,0000,,Realize that given n yes-or-no questions, Dialogue: 0,0:06:14.54,0:06:20.02,Default,,0000,0000,0000,,there are 2 to the power of n possible answer sequences. Dialogue: 0,0:06:20.02,0:06:24.24,Default,,0000,0000,0000,,Now in 1605, Francis Bacon clearly explained Dialogue: 0,0:06:24.24,0:06:26.79,Default,,0000,0000,0000,,how this idea could allow one to send Dialogue: 0,0:06:26.79,0:06:28.85,Default,,0000,0000,0000,,all letters of the alphabet, Dialogue: 0,0:06:28.85,0:06:31.14,Default,,0000,0000,0000,,using only a single difference. Dialogue: 0,0:06:31.14,0:06:34.65,Default,,0000,0000,0000,,[Regarding] his 'bilateral cipher,' Bacon wrote, famously: Dialogue: 0,0:06:34.65,0:06:37.54,Default,,0000,0000,0000,,"The transposition of two letters by five placings Dialogue: 0,0:06:37.54,0:06:40.73,Default,,0000,0000,0000,,will be sufficient for 32 differences. Dialogue: 0,0:06:40.73,0:06:44.11,Default,,0000,0000,0000,,For by this art, a way is opened whereby a man Dialogue: 0,0:06:44.11,0:06:47.07,Default,,0000,0000,0000,,may express and signify the intentions of his mind – Dialogue: 0,0:06:47.07,0:06:51.07,Default,,0000,0000,0000,,at any distance of place – with objects which are capable Dialogue: 0,0:06:51.07,0:06:53.22,Default,,0000,0000,0000,,of a two-fold difference only." Dialogue: 0,0:06:53.22,0:06:56.54,Default,,0000,0000,0000,,This simple idea of using a single difference Dialogue: 0,0:06:56.54,0:06:58.54,Default,,0000,0000,0000,,to communicate [all of the letters of] the alphabet Dialogue: 0,0:06:58.54,0:07:01.42,Default,,0000,0000,0000,,really took flight in the 17th century, Dialogue: 0,0:07:01.42,0:07:03.61,Default,,0000,0000,0000,,due to the invention of the telescope Dialogue: 0,0:07:03.61,0:07:08.18,Default,,0000,0000,0000,,by Lippershey, in 1608, and Galileo, in 1609. Dialogue: 0,0:07:08.18,0:07:11.34,Default,,0000,0000,0000,,Because quickly, the maginification power of the human eye Dialogue: 0,0:07:11.34,0:07:15.93,Default,,0000,0000,0000,,jumped from 3, to 8, to 33 times – and beyond. Dialogue: 0,0:07:15.93,0:07:18.07,Default,,0000,0000,0000,,So the observation of a single difference Dialogue: 0,0:07:18.07,0:07:21.24,Default,,0000,0000,0000,,could be made at a much greater distance. Dialogue: 0,0:07:22.72,0:07:26.33,Default,,0000,0000,0000,,Robert Hooke, an English polymath interested in Dialogue: 0,0:07:26.33,0:07:30.13,Default,,0000,0000,0000,,improving the capability of human vision, using lenses, Dialogue: 0,0:07:30.13,0:07:34.86,Default,,0000,0000,0000,,ignited progress when he told the Royal Society, in 1684, Dialogue: 0,0:07:34.86,0:07:37.92,Default,,0000,0000,0000,,that suddenly, "with a little practice, Dialogue: 0,0:07:37.92,0:07:41.01,Default,,0000,0000,0000,,the same character may be seen at Paris, Dialogue: 0,0:07:41.03,0:07:45.55,Default,,0000,0000,0000,,within a minute after it hath been exposed at London." Dialogue: 0,0:07:45.55,0:07:48.03,Default,,0000,0000,0000,,This was followed by a flood of inventions Dialogue: 0,0:07:48.03,0:07:50.97,Default,,0000,0000,0000,,to pass differences more effectively Dialogue: 0,0:07:50.97,0:07:54.15,Default,,0000,0000,0000,,across greater distances. Dialogue: 0,0:07:54.15,0:07:58.83,Default,,0000,0000,0000,,One technology, from 1795, perfectly demonstrates Dialogue: 0,0:07:58.83,0:08:02.35,Default,,0000,0000,0000,,the use of a single difference to communicate all things. Dialogue: 0,0:08:02.35,0:08:05.70,Default,,0000,0000,0000,,Lord George Murray's 'shutter telegraph' Dialogue: 0,0:08:05.70,0:08:09.93,Default,,0000,0000,0000,,was Britain's reaction to the Bonapartist threat to England. Dialogue: 0,0:08:09.93,0:08:12.78,Default,,0000,0000,0000,,It was composed of six rotating shutters, Dialogue: 0,0:08:12.78,0:08:16.58,Default,,0000,0000,0000,,which could be oriented as either 'open' or 'closed.' Dialogue: 0,0:08:16.58,0:08:19.88,Default,,0000,0000,0000,,Here, each shutter can be thought of as a single difference. Dialogue: 0,0:08:19.88,0:08:24.48,Default,,0000,0000,0000,,With six shutters, we have six questions: open or closed – Dialogue: 0,0:08:24.48,0:08:29.50,Default,,0000,0000,0000,,providing us with 2^6, or 64, differences – Dialogue: 0,0:08:29.50,0:08:33.66,Default,,0000,0000,0000,,enough for all letters, digits, and more. Dialogue: 0,0:08:33.66,0:08:37.66,Default,,0000,0000,0000,,Now realize that each observation of the shutter telegraph Dialogue: 0,0:08:37.66,0:08:39.89,Default,,0000,0000,0000,,can also be thought of as the observation Dialogue: 0,0:08:39.89,0:08:45.06,Default,,0000,0000,0000,,of one of 64 different paths through a decision tree. Dialogue: 0,0:08:51.69,0:08:55.24,Default,,0000,0000,0000,,And with a telescope, it was now possible to send letters Dialogue: 0,0:08:55.24,0:08:58.74,Default,,0000,0000,0000,,at an incredible distance between beacons. Dialogue: 0,0:08:58.74,0:09:01.16,Default,,0000,0000,0000,,However, an observation in 1820 Dialogue: 0,0:09:01.16,0:09:03.80,Default,,0000,0000,0000,,led to a revolutionary technology, Dialogue: 0,0:09:03.80,0:09:07.28,Default,,0000,0000,0000,,which forever changed how far these differences Dialogue: 0,0:09:07.28,0:09:10.21,Default,,0000,0000,0000,,could travel between signaling beacons. Dialogue: 0,0:09:10.21,0:09:12.34,Default,,0000,0000,0000,,This ushered in new ideas Dialogue: 0,0:09:12.34,0:09:16.60,Default,,0000,0000,0000,,which launched us into the 'Information Age.'