WEBVTT - What Do A.M., P.M., and SOS Stand For? 0:00:01.840 --> 0:00:07.920 Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff, Lauren 0:00:07.920 --> 0:00:12.879 bolbabam here. Because language is a wide and wondrous thing, 0:00:13.240 --> 0:00:17.040 we humans encounter new or new to us words all 0:00:17.079 --> 0:00:20.720 the time. Anything from a book you're reading for fun, 0:00:20.880 --> 0:00:23.000 to an article about a subject you're only sort of 0:00:23.040 --> 0:00:26.040 familiar with, to a fancy restaurant menu might have you 0:00:26.160 --> 0:00:30.400 diving for a dictionary, and even dictionaries have to update 0:00:30.440 --> 0:00:34.599 all the time to accommodate our linguistic innovations. For example, 0:00:34.840 --> 0:00:37.440 just in March of twenty twenty six, the Oxford English 0:00:37.520 --> 0:00:42.120 Dictionary added a definition for doom scroll. But on the 0:00:42.159 --> 0:00:45.360 flip side, there are some words or abbreviations that we 0:00:45.479 --> 0:00:48.159 know the practical meaning of that we might even use 0:00:48.200 --> 0:00:53.880 every day without having any idea of what they actually mean. Today, 0:00:54.080 --> 0:00:56.800 let's talk about a few of those. AM and PM 0:00:57.160 --> 0:01:04.160 and sos. First, up, AM and PM. Okay, many parts 0:01:04.200 --> 0:01:07.039 of the world use a twenty four hour clock instead 0:01:07.080 --> 0:01:10.000 of one o'clock in the afternoon. Someone in Turkey or 0:01:10.080 --> 0:01:14.360 Brazil might tell you it's thirteen hundred hours. But in 0:01:14.400 --> 0:01:17.640 places that use the twelve hour clock, like the United States, 0:01:17.959 --> 0:01:21.959 we use the concept of AM and PM. One of 0:01:22.000 --> 0:01:25.240 the inconvenient things about breaking your twenty four hour day 0:01:25.360 --> 0:01:28.319 into two twelve hour chunks numbered one through twelve, which 0:01:28.360 --> 0:01:31.839 turnover at midday and midnight, is that it becomes necessary 0:01:31.880 --> 0:01:35.160 to tell someone which chunk you're talking about. Are we 0:01:35.240 --> 0:01:37.200 meeting at eight in the morning or eight at night? 0:01:38.360 --> 0:01:41.280 You can often use context clues, but it is for 0:01:41.360 --> 0:01:44.479 this reason that the two periods are called AM, which 0:01:44.560 --> 0:01:48.160 is short for the Latin term anti meridium or before midday, 0:01:48.640 --> 0:01:52.400 and PM, which is short for post meritium or after 0:01:52.600 --> 0:01:57.560 mid day midday or meridium. Here is in the astronomical 0:01:57.600 --> 0:02:02.120 sense of when the sun passes the meridian overhead. The 0:02:02.200 --> 0:02:05.560 meridian is an imaginary circle that runs around our planet 0:02:05.640 --> 0:02:09.679 from any given point of view from wherever you're standing, 0:02:09.960 --> 0:02:13.480 the meridian passes through the north and south celestial poles, 0:02:13.919 --> 0:02:16.440 you know, the north and south points of the planet's axis, 0:02:17.120 --> 0:02:21.200 and it's also perpendicular to the horizon, so it includes 0:02:21.240 --> 0:02:24.840 the highest point in the sky above you. The sun 0:02:24.919 --> 0:02:29.720 passing through the meridian is essentially high noon. But let's 0:02:29.720 --> 0:02:32.840 back up a little. Why are we complicating things with 0:02:32.880 --> 0:02:35.000 a twelve hour clock in the first place, When the 0:02:35.040 --> 0:02:38.560 twenty four hour clock seems so much more straightforward and convenient. 0:02:39.680 --> 0:02:41.560 The answer to this has a lot to do with 0:02:41.720 --> 0:02:46.280 early clocks. The concept of AM and PM comes from 0:02:46.320 --> 0:02:49.720 the fact that ancient people used the convenient dark light 0:02:49.840 --> 0:02:52.800 contrast of each twenty four hour cycle to talk about 0:02:52.840 --> 0:02:55.200 what time it was. The sun pulled them what time 0:02:55.240 --> 0:02:57.280 it was in the day, and the moon and stars 0:02:57.320 --> 0:03:00.440 did the same at night. As early as thirty five 0:03:00.520 --> 0:03:04.800 hundred BCE, the ancient Egyptians built shadow casting obelisks that 0:03:04.880 --> 0:03:09.000 shaded sections of the ground throughout the day. These sections 0:03:09.040 --> 0:03:12.160 weren't as precise as modern hours, but the concept was 0:03:12.200 --> 0:03:16.360 the same. By fifteen hundred BCE, they had invented the 0:03:16.480 --> 0:03:19.760 more precise sun dial, and with it the hours we 0:03:19.840 --> 0:03:23.040 still know and love, ten daytime hours with a sunrise 0:03:23.080 --> 0:03:26.640 and sunset hour tacked on to either end. By six 0:03:26.760 --> 0:03:30.040 hundred BCE, that invented a timekeeping instrument for the night 0:03:30.120 --> 0:03:32.600 time as well. A person could align it with a 0:03:32.639 --> 0:03:35.640 pole star to track the passage of other stars through 0:03:35.640 --> 0:03:41.040 the meridian to tell time. Later clockmakers used the circular 0:03:41.120 --> 0:03:43.480 model of the sun dial to base the layout of 0:03:43.520 --> 0:03:47.800 their new technology. Although the first mechanical clocks in Europe 0:03:48.040 --> 0:03:51.440 built for medieval clock towers were twenty four hour devices. 0:03:52.000 --> 0:03:55.280 By the thirteen hundred CE, mechanical clocks began to be 0:03:55.320 --> 0:03:58.960 built with twelve hour faces, perhaps to save space and 0:03:59.040 --> 0:04:03.960 eyestrain for people carrying pocket watches. By the mid fifteen hundreds, 0:04:04.080 --> 0:04:07.640 English speaking people in the maths and sciences like John Deeve, 0:04:07.760 --> 0:04:10.680 who were using twelve hour cycles, had adopted the Latin 0:04:10.720 --> 0:04:15.240 phrases anti meritium and post meridium, Latin being the scientific 0:04:15.320 --> 0:04:19.279 lingua franca of the time. By the mid sixteen hundreds, 0:04:19.320 --> 0:04:22.920 the abbreviations AM and PM were in use by scientists 0:04:22.960 --> 0:04:27.479 like Nicholas Culpepper. Both the full terms and the abbreviations 0:04:27.520 --> 0:04:31.920 trickled into common usage after that, even though these designations 0:04:31.960 --> 0:04:36.640 didn't have much to do with the astronomical bodies anymore. However, 0:04:36.920 --> 0:04:40.200 by the late eighteen hundreds, starting with the Canadian Pacific 0:04:40.279 --> 0:04:44.599 Railway in eighteen eighty six, more countries and military entities 0:04:44.720 --> 0:04:48.239 started telling time based on the twenty four hour clock. Again. 0:04:49.440 --> 0:04:52.679 With the exception of countries like the US, Australia, Canada, 0:04:52.720 --> 0:04:54.920 and the Philippines or where the twelve hour system is 0:04:54.960 --> 0:04:58.560 officially used, most other countries officially use a twenty four 0:04:58.560 --> 0:05:03.080 hour clock, but ancient habits die hard. If you ask 0:05:03.160 --> 0:05:06.920 someone in Ireland, China, or France the time, they're equally 0:05:07.000 --> 0:05:12.520 likely to use AM and PM. But okay, let's switch 0:05:12.560 --> 0:05:17.479 over to another common term, SOS. Even children at play 0:05:17.640 --> 0:05:20.200 know that when you are in a life threatening emergency, 0:05:20.720 --> 0:05:23.039 maybe you need to be rescued from an island filled 0:05:23.040 --> 0:05:26.560 with man eating crabs that's also surrounded by lava. The 0:05:26.600 --> 0:05:28.719 way you let the world know that you're in trouble 0:05:29.000 --> 0:05:33.960 is to shout three simple letters SOS. You can write 0:05:34.000 --> 0:05:36.479 them on the beach, send them via Morse code, or 0:05:36.520 --> 0:05:38.720 write them on your hand and flash them at pastors by. 0:05:39.960 --> 0:05:42.479 We all know that sending out an SOS signal is 0:05:42.480 --> 0:05:47.080 a request for rescue. So what does SOS mean? Is 0:05:47.080 --> 0:05:51.080 it an abbreviation? What did the letters stand for? This 0:05:51.279 --> 0:05:55.400 was new to me today. The letters SOS stand for nothing, 0:05:56.400 --> 0:05:59.719 not save our ship, not save our souls. It wasn't 0:05:59.760 --> 0:06:03.240 even originally designed to stand for letters of the English alphabet. 0:06:04.440 --> 0:06:07.560 SOS came to us as a replacement for visual distress 0:06:07.600 --> 0:06:11.600 signals during the early days of long distance electromagnetic communication. 0:06:13.040 --> 0:06:16.240 Samuel Morse developed what would become Morse code, alongside his 0:06:16.320 --> 0:06:19.760 contributions to a telegraph machine that could send messages using 0:06:19.800 --> 0:06:24.120 electrical signals over a wire in the eighteen forties. In 0:06:24.240 --> 0:06:27.920 Morse code, dots and dashes are assembled in different configurations 0:06:28.000 --> 0:06:31.880 to represent the different letters of the alphabet. In this way, 0:06:32.080 --> 0:06:36.080 messages could be sent across countries via wired telegraph networks, and, 0:06:36.400 --> 0:06:40.279 starting in the early nineteen hundreds, wirelessly across oceans and 0:06:40.320 --> 0:06:44.600 then around the world using radio equipment. SOS came in 0:06:44.760 --> 0:06:49.039 during the transition between the two. In nineteen oh five, 0:06:49.200 --> 0:06:52.440 the German government, but which had leaned into telegraph systems early, 0:06:52.920 --> 0:06:57.880 published their regulations for the control of Spark Telegraphy. It 0:06:58.040 --> 0:07:01.960 mandated that German wireless operator use dot dot dot dash 0:07:02.040 --> 0:07:07.240 dash dash dot dot dot to signal an emergency. This 0:07:07.400 --> 0:07:10.240 didn't really have anything to do with letters of the alphabet, 0:07:10.480 --> 0:07:13.480 but it was quick and easy to type and difficult 0:07:13.480 --> 0:07:17.800 to mistake for anything else. It also happened to spell 0:07:17.960 --> 0:07:22.120 SOS in Morse code. Everyone agreed it was way better 0:07:22.160 --> 0:07:26.440 than SSSDDD, which is what the Italians were pushing for. 0:07:26.560 --> 0:07:29.679 At the International Radio Telegraph Convention in nineteen oh six, 0:07:30.960 --> 0:07:34.080 the term SOS was voted in as the official international 0:07:34.080 --> 0:07:37.280 distress signal and went into effect July first of nineteen 0:07:37.280 --> 0:07:42.600 oh eight. It didn't catch on everywhere immediately. For instance, 0:07:42.720 --> 0:07:46.960 the British Marconi International Marine Communication Company, which outfitted ships 0:07:47.000 --> 0:07:51.480 with radio equipment, preferred the distress code CQD in Morse code, 0:07:51.640 --> 0:07:54.680 and continued using it after the SOS call was established 0:07:54.720 --> 0:07:59.280 as the international standard. In fact, CQD was the first 0:07:59.320 --> 0:08:02.280 distress code sent by the radio operators on the Titanic 0:08:02.360 --> 0:08:05.400 in nineteen twelve when the ship hit Iceberg, although they 0:08:05.480 --> 0:08:09.400 did send the SOS signal as well. Early radios, like 0:08:09.400 --> 0:08:14.680 the Titanics couldn't transmit sounds, only electrical signals. Once inventors 0:08:14.720 --> 0:08:17.920 figured out how to encode speech, the verbal signal may 0:08:18.000 --> 0:08:21.160 day was picked up at the International Radio Telegraphic Convention 0:08:21.440 --> 0:08:24.680 in nineteen twenty seven. As we've talked about on the 0:08:24.680 --> 0:08:27.840 show before, may day is derived from the French madeir, 0:08:28.240 --> 0:08:33.120 which means help me, but SOS cannot be ousted. Although 0:08:33.160 --> 0:08:36.840 mayday is used in voice communication, SOS is still used 0:08:36.840 --> 0:08:41.480 as shorthand or anywhere that non verbal communication must be used. 0:08:46.280 --> 0:08:49.000 Today's episode is based on the articles what do am 0:08:49.080 --> 0:08:52.000 and PM stand for and what does SOS Mean? On 0:08:52.000 --> 0:08:55.960 HowStuffWorks dot Com, both written by Jesslynshields. Brain Stuff is 0:08:56.000 --> 0:08:58.600 production of by Heart Radio in partnership with houstuffworks dot 0:08:58.600 --> 0:09:01.760 Com and is produced by Tyler Playing Before. More podcasts 0:09:01.760 --> 0:09:05.120 from my heart Radio, visit the iHeartRadio app, Apple Podcasts, 0:09:05.200 --> 0:09:07.040 or wherever you listen to your favorite shows.