WEBVTT 00:00:07.589 --> 00:00:10.470 Howdy stargazers and welcome to Star Trails. 00:00:10.650 --> 00:00:13.130 I'm Drew and I'll be your guide to the night 00:00:13.130 --> 00:00:15.710 sky for the week of November the 2nd through 00:00:15.710 --> 00:00:19.089 the 8th. This week we're talking about messages, 00:00:19.449 --> 00:00:22.429 the kind we send across the cosmos and the ones 00:00:22.429 --> 00:00:26.030 written in starlight. I'll share a quick observation 00:00:26.030 --> 00:00:28.850 report before we dive into what's happening overhead 00:00:28.850 --> 00:00:32.390 this week. Then in the second half of the show, 00:00:32.609 --> 00:00:35.189 we'll turn our gaze from the backyard to deep 00:00:35.189 --> 00:00:39.210 space to revisit the Arecibo message, the radio 00:00:39.210 --> 00:00:42.229 signal humanity beamed toward the stars more 00:00:42.229 --> 00:00:45.429 than 50 years ago. We'll break down what it said, 00:00:45.590 --> 00:00:49.130 how it worked, and whether anyone, human or otherwise, 00:00:49.429 --> 00:00:53.350 could ever decode it. Before we get into this 00:00:53.350 --> 00:00:55.929 week's night sky, I'd like to take a moment to 00:00:55.929 --> 00:00:59.070 report on the star party I attended last week. 00:00:59.320 --> 00:01:02.820 Last Saturday, my local club was holding their 00:01:02.820 --> 00:01:05.780 fall cookout at their dark sky site about an 00:01:05.780 --> 00:01:09.319 hour north of where I live. This year, I had 00:01:09.319 --> 00:01:12.060 high hopes to get in some serious stargazing. 00:01:12.340 --> 00:01:14.920 In particular, I wanted to get eyes on comet 00:01:14.920 --> 00:01:19.819 A6 Lemon and maybe even photograph it. We'd had 00:01:19.819 --> 00:01:22.540 cooler weather and clear blue skies all week, 00:01:22.599 --> 00:01:25.680 but as I made my way to the site Saturday afternoon, 00:01:26.000 --> 00:01:29.000 I noticed some ominous haze on the horizon and 00:01:29.000 --> 00:01:32.260 high -altitude clouds moving in. Just before 00:01:32.260 --> 00:01:35.659 6 p .m., I was welcomed by club president and 00:01:35.659 --> 00:01:39.159 friend of the podcast, Mike Roberts, occupying 00:01:39.159 --> 00:01:42.739 his important position at the grill. If nothing 00:01:42.739 --> 00:01:45.780 else, we'd have a good meal. And it turns out 00:01:45.780 --> 00:01:47.840 that may have been the highlight of the night. 00:01:48.170 --> 00:01:51.950 Just before 7 p .m. in the fading twilight, I 00:01:51.950 --> 00:01:55.689 scanned the sky for lemon with my 11 by 70 binoculars. 00:01:56.250 --> 00:01:59.670 Some low -lying clouds finally drifted away and 00:01:59.670 --> 00:02:02.950 the comet emerged in my field of view, resembling 00:02:02.950 --> 00:02:08.050 a small, very dim, hazy snowball. In the binoculars, 00:02:08.069 --> 00:02:11.150 I could detect a hint of a tail. If I hadn't 00:02:11.150 --> 00:02:13.669 been looking for it, I could have easily swept 00:02:13.669 --> 00:02:16.490 right past it. The only thing that gave it away 00:02:16.490 --> 00:02:19.189 was that it looked soft and fuzzy against the 00:02:19.189 --> 00:02:23.210 neighboring in focus stars. Having spotted lemon, 00:02:23.409 --> 00:02:26.330 I decided to try for a photo. Since I only had 00:02:26.330 --> 00:02:29.289 my camera and some normal lenses, it would have 00:02:29.289 --> 00:02:34.150 to be a wide field shot. At 70mm on a full frame 00:02:34.150 --> 00:02:37.930 camera, it was woefully small, but the coma and 00:02:37.930 --> 00:02:42.169 tail were visible enough. I stepped up to 200mm, 00:02:42.550 --> 00:02:44.990 and the results weren't much better on single 00:02:44.990 --> 00:02:48.349 exposure shots, so I won't be showing these off 00:02:48.349 --> 00:02:52.430 anywhere. By then, the clouds were rolling in 00:02:52.430 --> 00:02:55.569 around that portion of the sky, so I aimed higher, 00:02:55.750 --> 00:02:58.530 catching the Andromeda galaxy in binoculars, 00:02:59.110 --> 00:03:02.900 another fuzzy blob at this magnification. The 00:03:02.900 --> 00:03:06.599 Milky Way's dim river of light was crossing directly 00:03:06.599 --> 00:03:09.840 overhead, with Cygnus the Swan gliding along 00:03:09.840 --> 00:03:14.199 its path. We spotted numerous satellites drifting 00:03:14.199 --> 00:03:18.520 by, all of them starlings, of course. After about 00:03:18.520 --> 00:03:21.780 an hour, the atmospheric haze seemed to multiply 00:03:21.780 --> 00:03:24.759 and the sky was looking gray rather than black. 00:03:25.400 --> 00:03:27.759 The seeing tanked, so I packed up and headed 00:03:27.759 --> 00:03:31.530 home. Sometimes, it seems like these star parties 00:03:31.530 --> 00:03:34.250 are cursed, and then there are nights when the 00:03:34.250 --> 00:03:37.349 sky is so clear the stars seem to hover just 00:03:37.349 --> 00:03:40.449 feet above us. If nothing else, there's food, 00:03:40.949 --> 00:03:43.289 camaraderie, and an array of scopes to check 00:03:43.289 --> 00:03:46.229 out. If you've ever wondered what a star party 00:03:46.229 --> 00:03:50.069 is like, go back and listen to episode 41, where 00:03:50.069 --> 00:03:53.229 I combined the sights and sounds of a party into 00:03:53.229 --> 00:04:03.039 an immersive first -person report. This week 00:04:03.039 --> 00:04:06.500 the moon takes center stage. It begins the week 00:04:06.500 --> 00:04:09.680 as a waxing gibbous, bright and nearly full, 00:04:09.879 --> 00:04:12.979 and reaches its full phase on Wednesday, also 00:04:12.979 --> 00:04:16.899 known as the beaver moon. This one's also a super 00:04:16.899 --> 00:04:19.459 moon, appearing a touch larger and brighter than 00:04:19.459 --> 00:04:22.100 usual, as it makes one of its closest approaches 00:04:22.100 --> 00:04:25.339 to Earth this year. After that, the moon begins 00:04:25.339 --> 00:04:28.480 to wane, spending the weekend as a waning gibbous 00:04:28.480 --> 00:04:31.399 rising later each night. The moon will light 00:04:31.399 --> 00:04:34.240 up the sky all week, so it's not the best time 00:04:34.240 --> 00:04:37.339 for chasing faint nebula or galaxies. But if 00:04:37.339 --> 00:04:40.800 you're into lunar photography or moonlit landscapes, 00:04:41.399 --> 00:04:44.680 these bright nights are perfect. That high -contrast 00:04:44.680 --> 00:04:48.459 autumn air makes craters, mountains, and maria 00:04:48.459 --> 00:04:51.319 pop beautifully through binoculars or even a 00:04:51.319 --> 00:04:55.779 small telescope. As for the planets, Saturn hangs 00:04:55.779 --> 00:04:58.879 low in the southeastern sky just after sunset, 00:04:59.160 --> 00:05:02.660 shining with a steady golden light. It drifts 00:05:02.660 --> 00:05:05.019 southward throughout the evening, setting before 00:05:05.019 --> 00:05:08.779 midnight. Jupiter rises later in the night and 00:05:08.779 --> 00:05:11.819 commands the morning sky. You'll find it high 00:05:11.819 --> 00:05:15.079 in the east -southeast before dawn, bright and 00:05:15.079 --> 00:05:18.439 unmistakable. Through a telescope, its cloud 00:05:18.439 --> 00:05:21.560 bands and the four Galilean moons are always 00:05:21.560 --> 00:05:25.360 worth a look. Venus joins the morning show as 00:05:25.360 --> 00:05:28.639 well, the bright morning star gleaming low in 00:05:28.639 --> 00:05:32.100 the east before sunrise. It's slowly sinking 00:05:32.100 --> 00:05:35.740 toward the sun as November goes on, so catch 00:05:35.740 --> 00:05:39.420 it early while it's still prominent. Mercury 00:05:39.420 --> 00:05:42.180 is hiding too close to the sun this week and 00:05:42.180 --> 00:05:45.459 Mars remains faint and distant, but both will 00:05:45.459 --> 00:05:48.819 become more interesting later this year. The 00:05:48.819 --> 00:05:52.509 autumn zodiac still dominates the evening. Pisces, 00:05:52.850 --> 00:05:55.810 Aries, and Taurus spread out across the southern 00:05:55.810 --> 00:05:59.170 sky, while the great winter constellations are 00:05:59.170 --> 00:06:02.610 just starting to rise. If you stay up late, look 00:06:02.610 --> 00:06:05.389 towards the east and you'll see Orion beginning 00:06:05.389 --> 00:06:08.709 to climb above the horizon, a reassuring sign 00:06:08.709 --> 00:06:11.389 that the bright winter sky is around the corner. 00:06:13.079 --> 00:06:16.879 Coming up, we revisit the Arecibo signal, the 00:06:16.879 --> 00:06:19.879 message fired into space more than 50 years ago 00:06:19.879 --> 00:06:23.620 as a greeting to intelligent life. We'll take 00:06:23.620 --> 00:06:26.379 a look at the format of the message and investigate 00:06:26.379 --> 00:06:29.279 if an alien species could even figure out how 00:06:29.279 --> 00:06:32.879 to decode the message if they received it. To 00:06:32.879 --> 00:06:35.500 find out, we're going to generate our own version 00:06:35.500 --> 00:06:39.079 of the message and build our own decoder. That's 00:06:39.079 --> 00:06:55.579 after the break. Stay with us. Welcome back. 00:06:56.800 --> 00:06:59.980 In our last show, we examined the idea of the 00:06:59.980 --> 00:07:03.939 Fermi paradox, the idea that in a universe so 00:07:03.939 --> 00:07:07.079 vast, how is it possible we haven't communicated 00:07:07.079 --> 00:07:10.639 with any other species? And if you heard the 00:07:10.639 --> 00:07:12.980 episode, you might recall that we spent some 00:07:12.980 --> 00:07:16.079 time describing one of humankind's attempts to 00:07:16.079 --> 00:07:20.019 reach out to extraterrestrial life. Of course, 00:07:20.019 --> 00:07:23.370 I'm talking about the Arecibo message. a burst 00:07:23.370 --> 00:07:28.870 of binary code sent from Earth in 1974. It lasted 00:07:28.870 --> 00:07:31.649 just under three minutes, and though it was meant 00:07:31.649 --> 00:07:34.670 for ETs, I've often wondered if anyone could 00:07:34.670 --> 00:07:38.189 actually decode it if they received it. That's 00:07:38.189 --> 00:07:42.649 the subject of this half of the show. We're going 00:07:42.649 --> 00:07:45.110 to take the original binary message intended 00:07:45.110 --> 00:07:48.699 for the stars and turn it into audio. Then we're 00:07:48.699 --> 00:07:52.000 going to decode that audio in a modern way and 00:07:52.000 --> 00:07:54.939 see if we can reproduce the Arecibo signal the 00:07:54.939 --> 00:07:58.540 way in which it was intended to be seen. We may 00:07:58.540 --> 00:08:00.839 get into the weeds with some jargon along the 00:08:00.839 --> 00:08:03.360 way, but I promise I'll try and make it make 00:08:03.360 --> 00:08:08.220 sense. First, let's set the scene. The story 00:08:08.220 --> 00:08:11.480 begins at the Arecibo Observatory in Puerto Rico. 00:08:11.720 --> 00:08:16.600 It's November the 16th, 1974, and the telescope 00:08:16.600 --> 00:08:20.500 has just undergone a major upgrade. To celebrate, 00:08:21.019 --> 00:08:24.160 scientists Frank Drake and Carl Sagan wanted 00:08:24.160 --> 00:08:27.639 to do something audacious. So they decided to 00:08:27.639 --> 00:08:32.320 send a message to the stars. Arecibo was the 00:08:32.320 --> 00:08:35.600 most powerful radio telescope on Earth at that 00:08:35.600 --> 00:08:40.639 time. A 305 meter dish carved into a limestone 00:08:40.639 --> 00:08:44.570 valley. It could transmit a million watts at 00:08:44.570 --> 00:08:50.710 2380 megahertz, a frequency in the S band far 00:08:50.710 --> 00:08:53.690 above radio frequencies we generally listen to. 00:08:54.990 --> 00:08:58.049 To send a message into space, the team at Arecibo 00:08:58.049 --> 00:09:02.269 used a technique called phase modulation, essentially 00:09:02.269 --> 00:09:05.710 flipping the phase or rhythm of a radio wave 00:09:05.710 --> 00:09:08.889 back and forth to represent the ones and zeros 00:09:08.889 --> 00:09:13.419 of a binary message. We didn't transmit audio 00:09:13.419 --> 00:09:18.320 or spoken words into space, just pure data, and 00:09:18.320 --> 00:09:21.220 at that time it was the most powerful signal 00:09:21.220 --> 00:09:25.120 to leave Earth. The signal's final destination 00:09:25.120 --> 00:09:28.860 is the globular cluster M13 in the constellation 00:09:28.860 --> 00:09:35.500 Hercules, 25 ,000 light years away. M13 was selected 00:09:35.500 --> 00:09:37.879 because it was in the sky when the signal was 00:09:37.879 --> 00:09:41.840 scheduled to be sent. Crafted by Drake and Sagan, 00:09:42.139 --> 00:09:44.879 the message was a postcard to the cosmos that 00:09:44.879 --> 00:09:49.500 said, we're here. When decoded, the signal reveals 00:09:49.500 --> 00:09:52.679 quite a bit of information about the human experience, 00:09:53.100 --> 00:09:56.340 our science, our genetic makeup, where we are 00:09:56.340 --> 00:09:59.740 in the universe, and even more. But could anyone 00:09:59.740 --> 00:10:02.879 figure out how to convert the signal to meaningful 00:10:02.879 --> 00:10:06.649 data? To try and answer that question, let's 00:10:06.649 --> 00:10:09.129 look at what it takes to create such a signal 00:10:09.129 --> 00:10:12.549 and how we can use some relatively simple tools 00:10:12.549 --> 00:10:16.009 to crack the code. We'll start the investigation 00:10:16.009 --> 00:10:18.289 by learning a little more about the signal and 00:10:18.289 --> 00:10:21.370 its structure because the key to unraveling it 00:10:21.370 --> 00:10:25.690 lies in simple math. The message itself was exactly 00:10:25.690 --> 00:10:31.889 1679 bits long. When we refer to a bit, we're 00:10:31.889 --> 00:10:35.710 talking about a single on or off state, or in 00:10:35.710 --> 00:10:40.669 this case, a one or a zero binary. The number 00:10:40.669 --> 00:10:45.870 of bits in the message 1 ,679 was not chosen 00:10:45.870 --> 00:10:49.470 at random. It's the result of multiplying two 00:10:49.470 --> 00:10:54.230 prime numbers, 23 and 73, and that's the first 00:10:54.230 --> 00:10:58.509 key to unlocking the puzzle. If you arrange the 00:10:58.509 --> 00:11:01.669 sequence of 1s and 0s into a tall rectangle, 00:11:02.049 --> 00:11:06.610 23 columns across and 73 rows down, a picture 00:11:06.610 --> 00:11:11.789 emerges. The 0s represent a space, the 1s represent 00:11:11.789 --> 00:11:15.490 a graphical block. You could even use a spreadsheet 00:11:15.490 --> 00:11:18.889 or graph paper and plot the 1s and 0s into a 00:11:18.889 --> 00:11:22.929 23 by 73 grid and see the familiar pattern of 00:11:22.929 --> 00:11:26.379 the signal emerge. Any other combination results 00:11:26.379 --> 00:11:30.659 in a muddled message. Now let's break down the 00:11:30.659 --> 00:11:34.419 resulting image or pictograph from top to bottom. 00:11:34.919 --> 00:11:37.700 You've probably seen it in science books since 00:11:37.700 --> 00:11:42.620 the late 1970s. The sequence starts with a representation 00:11:42.620 --> 00:11:46.039 of the numbers 1 through 10 written in binary. 00:11:46.509 --> 00:11:50.190 Below that, the atomic numbers of hydrogen, carbon, 00:11:50.649 --> 00:11:53.809 nitrogen, oxygen, and phosphorus, the elements 00:11:53.809 --> 00:11:59.129 that form DNA. Then a diagram of DNA's double 00:11:59.129 --> 00:12:02.190 helix, with a number showing how many base pairs 00:12:02.190 --> 00:12:06.370 it contains. In the center, a little stick figure 00:12:06.370 --> 00:12:09.980 of a human next to a bar showing our height and 00:12:09.980 --> 00:12:13.799 a number indicating Earth's population in 1974. 00:12:14.480 --> 00:12:17.980 It was about four billion people. Beneath that, 00:12:18.059 --> 00:12:21.059 a row of nine dots representing the planets of 00:12:21.059 --> 00:12:24.159 our solar system, with the third one offset. 00:12:24.539 --> 00:12:28.320 That's Earth. And yep, Pluto was still considered 00:12:28.320 --> 00:12:32.059 a planet back then. Finally, at the bottom, there's 00:12:32.059 --> 00:12:35.259 a representation of the Arecibo telescope itself, 00:12:35.379 --> 00:12:39.750 with a coded version of its diameter. The signal 00:12:39.750 --> 00:12:42.409 was designed to be so universal that it didn't 00:12:42.409 --> 00:12:45.669 require spoken language to read it, just logic 00:12:45.669 --> 00:12:49.049 and math. If you've ever read or seen the movie 00:12:49.049 --> 00:12:52.470 Contact, which was written by Sagan, you might 00:12:52.470 --> 00:12:55.490 recall prime numbers were also used there to 00:12:55.490 --> 00:12:59.610 decode a message from the stars. Primes are useful 00:12:59.610 --> 00:13:01.710 in this field because they're mathematically 00:13:01.710 --> 00:13:05.850 special, not likely to occur naturally as arranged 00:13:05.850 --> 00:13:09.860 signals or patterns in nature. Sagan used them 00:13:09.860 --> 00:13:13.059 as the logical bearer of meaning before words 00:13:13.059 --> 00:13:16.659 or images. Fortunately, we know this going into 00:13:16.659 --> 00:13:20.519 our experiment. To see how readable the signal 00:13:20.519 --> 00:13:23.700 really is, I decided to recreate it using modern 00:13:23.700 --> 00:13:27.399 tools. My weapon of choice is the general purpose 00:13:27.399 --> 00:13:30.860 programming language of Python. It's a language 00:13:30.860 --> 00:13:33.679 I have some experience with, and the high level 00:13:33.679 --> 00:13:36.740 nature of Python means coders have access to 00:13:36.740 --> 00:13:40.200 some really advanced functions, such as modules 00:13:40.200 --> 00:13:43.059 that do the heavy lifting of signal generation 00:13:43.059 --> 00:13:47.539 and analysis. Basically, I set out to create 00:13:47.539 --> 00:13:52.159 a software modem to modulate and demodulate the 00:13:52.159 --> 00:13:56.139 Arecibo signal. With some lines of Python, I 00:13:56.139 --> 00:13:59.360 took the original binary sequence from Wikipedia. 00:13:59.690 --> 00:14:06.330 all 1679 bits, and I mapped it to sound. I decided 00:14:06.330 --> 00:14:10.169 to use a protocol inspired by my ham radio experience, 00:14:10.889 --> 00:14:15.750 frequency shifted keying, or FSK. With this technique, 00:14:15.950 --> 00:14:18.750 I assigned specific audio frequencies to the 00:14:18.750 --> 00:14:25.129 ones and zeros. In this case, 1200 and 1800 hertz. 00:14:26.420 --> 00:14:29.580 It's essentially the same principle ham radio 00:14:29.580 --> 00:14:33.460 operators used in digital modes like radio teletype. 00:14:34.460 --> 00:14:37.840 To match the data rate of Arecibo, we're encoding 00:14:37.840 --> 00:14:41.220 at 10 bits per second, which results in a transmission 00:14:41.220 --> 00:14:44.940 of just under three minutes in length. Finally, 00:14:45.120 --> 00:14:48.240 the script outputs the binary stream as a WAV 00:14:48.240 --> 00:14:50.960 audio file that can be played on just about any 00:14:50.960 --> 00:14:55.490 device. At this point, our result is similar 00:14:55.490 --> 00:14:58.190 to the signal sent from Arecibo with a couple 00:14:58.190 --> 00:15:01.470 major differences. Since we're shifting between 00:15:01.470 --> 00:15:05.149 two audible frequencies, we've essentially sonified 00:15:05.149 --> 00:15:09.409 the raw data so that we can now hear it. Remember, 00:15:09.570 --> 00:15:12.549 the Arecibo message simply shifted the phase 00:15:12.549 --> 00:15:16.190 of a carrier wave to represent the data, so there 00:15:16.190 --> 00:15:18.909 wasn't much to actually listen to in the original 00:15:18.909 --> 00:15:22.860 transmission. For fun, I recreated the phase 00:15:22.860 --> 00:15:25.019 shifted version and it basically just sounds 00:15:25.019 --> 00:15:28.740 like one continuous tone. But to hear that tone, 00:15:29.080 --> 00:15:32.840 I had to lower the frequency by magnitudes. The 00:15:32.840 --> 00:15:35.919 Arecibo signal was sent at a frequency that is 00:15:35.919 --> 00:15:39.659 millions of times, no joke, millions, higher 00:15:39.659 --> 00:15:43.240 than what we can hear as humans. To explain it 00:15:43.240 --> 00:15:45.980 another way, for any musicians out there, check 00:15:45.980 --> 00:15:49.340 this out. To make the original Arecibo signal 00:15:49.340 --> 00:15:52.899 audible, we're reducing it in pitch by about 00:15:52.899 --> 00:15:56.620 1 .2 million octaves to bring it into the range 00:15:56.620 --> 00:16:01.139 of human hearing. As a result, our version sounds 00:16:01.139 --> 00:16:04.820 like a stream of robotic chirps and pulses. I 00:16:04.820 --> 00:16:07.200 could actually send it out into the ether with 00:16:07.200 --> 00:16:10.659 my ham radio transceiver if I wanted to, and 00:16:10.659 --> 00:16:14.279 someone could, in theory, decode it. They would 00:16:14.279 --> 00:16:17.000 need to understand the protocol, in other words, 00:16:17.340 --> 00:16:20.700 my data rate and how the data is structured once 00:16:20.700 --> 00:16:25.559 received. Essentially that 23 by 73 grid that 00:16:25.559 --> 00:16:31.159 I've mentioned. So to complete the circle, let's 00:16:31.159 --> 00:16:34.500 decode the message using another Python script 00:16:34.500 --> 00:16:37.519 and see if we can translate the audio data into 00:16:37.519 --> 00:16:41.000 the familiar visual of the Arecibo pictograph. 00:16:42.120 --> 00:16:46.059 We need to first load up the audio file for analysis, 00:16:46.539 --> 00:16:49.539 and fortunately Python contains libraries that 00:16:49.539 --> 00:16:53.059 do just that. Knowing the data rate of 10 bits 00:16:53.059 --> 00:16:56.059 per second, we segment the audio into windows 00:16:56.059 --> 00:16:59.740 of one -tenth of a second. For each window, we 00:16:59.740 --> 00:17:02.580 measure the energy of those two tones. Whichever 00:17:02.580 --> 00:17:06.299 frequency is stronger, either 1200 or 1800 Hz, 00:17:06.740 --> 00:17:12.309 becomes that bit's value, a 1 or a 0. Presumably, 00:17:12.390 --> 00:17:15.009 an alien species could analyze the message and 00:17:15.009 --> 00:17:17.630 see there is patterned information that appears 00:17:17.630 --> 00:17:20.930 in regular intervals. If you load up our wave 00:17:20.930 --> 00:17:24.349 file into an audio editor like Audacity, you 00:17:24.349 --> 00:17:26.950 can zoom into the waveforms and actually see 00:17:26.950 --> 00:17:30.750 the alternating tones. When you string these 00:17:30.750 --> 00:17:34.049 bits back together, you get the same binary sequence 00:17:34.049 --> 00:17:38.859 that left Earth in 1974. Using a graphic library 00:17:38.859 --> 00:17:42.019 in Python, we can plot the binary values into 00:17:42.019 --> 00:17:46.059 that 23 by 73 grid and pop out the resulting 00:17:46.059 --> 00:17:51.200 image as a PNG file. And there it is, the Arecibo 00:17:51.200 --> 00:17:54.900 message with its familiar DNA helix, stick figure, 00:17:55.079 --> 00:17:59.599 and radio dish perfectly recreated. If you'd 00:17:59.599 --> 00:18:02.400 like to try this for yourself, I'll make my code, 00:18:02.680 --> 00:18:05.579 WAV file, and resulting graphics available in 00:18:05.579 --> 00:18:08.660 the show notes. You'll need Python installed 00:18:08.660 --> 00:18:11.140 on whatever computer you're using. I'm using 00:18:11.140 --> 00:18:14.160 Linux, but Python runs on everything from Windows 00:18:14.160 --> 00:18:18.220 to Mac OS to systems on chip like the Raspberry 00:18:18.220 --> 00:18:23.460 Pi. So encoding and decoding the Arecibo signal 00:18:23.460 --> 00:18:26.279 is actually somewhat straightforward, but only 00:18:26.279 --> 00:18:28.980 because we already knew how it was constructed. 00:18:30.000 --> 00:18:32.460 Assuming an intelligent civilization made it 00:18:32.460 --> 00:18:35.160 this far, would they even understand what they're 00:18:35.160 --> 00:18:38.549 looking at? Can we as humans even understand 00:18:38.549 --> 00:18:42.089 it? A viewer would see the geometric shapes, 00:18:42.529 --> 00:18:45.470 stripes, dots, the stick figure of a human, but 00:18:45.470 --> 00:18:48.049 would you recognize the bar next to the human 00:18:48.049 --> 00:18:51.970 indicates its height in binary? Would you recognize 00:18:51.970 --> 00:18:55.529 that those five lines of dots are atomic numbers? 00:18:56.170 --> 00:19:00.230 Would you know the twin spirals are DNA? Even 00:19:00.230 --> 00:19:03.549 for us, the meaning only emerges because we already 00:19:03.549 --> 00:19:07.000 basically know the story. We know what DNA looks 00:19:07.000 --> 00:19:09.380 like. We know what a solar system looks like. 00:19:09.660 --> 00:19:13.099 We know what a human is. Maybe some folks even 00:19:13.099 --> 00:19:15.920 know how to convert binary to the familiar numbers 00:19:15.920 --> 00:19:20.599 of a base -10 system. An alien species wouldn't 00:19:20.599 --> 00:19:23.660 share those references. They might not even perceive 00:19:23.660 --> 00:19:27.240 visual patterns the way we do. Maybe they'd interpret 00:19:27.240 --> 00:19:30.119 the entire thing as a mathematical proof or a 00:19:30.119 --> 00:19:33.599 piece of music or a coordinate map. Or maybe 00:19:33.599 --> 00:19:36.480 they wouldn't recognize it as a message at all. 00:19:37.319 --> 00:19:40.519 The Arecibo pictograph looks self -explanatory 00:19:40.519 --> 00:19:44.359 to us because it is us, and that's the trap. 00:19:44.819 --> 00:19:48.160 It's anthropocentric. It's written in the language 00:19:48.160 --> 00:19:51.279 of human experience, dressed in the symbols of 00:19:51.279 --> 00:19:57.299 universal truth, yes or no, on or off. So imagine 00:19:57.299 --> 00:20:00.329 you're the one receiving it. an alien scientist 00:20:00.329 --> 00:20:03.410 staring at a stream of data from the sky. How 00:20:03.410 --> 00:20:07.230 would you even begin? Maybe you notice a repeating 00:20:07.230 --> 00:20:10.049 pattern of phase shifts. Okay, maybe that means 00:20:10.049 --> 00:20:16.190 it's digital. You count 1679 bits. You somehow 00:20:16.190 --> 00:20:20.589 realize that's 23 times 73, both prime numbers. 00:20:21.410 --> 00:20:24.109 You try arranging the bits. Maybe you find the 00:20:24.109 --> 00:20:27.769 right orientation and maybe not. And if you do, 00:20:27.930 --> 00:20:30.509 you're still faced with a puzzle made by a species 00:20:30.509 --> 00:20:33.309 you've never met, living on a world you've never 00:20:33.309 --> 00:20:37.150 seen, with no shared biology or shared reference 00:20:37.150 --> 00:20:40.930 frames. It's like solving a crossword puzzle 00:20:40.930 --> 00:20:45.890 in a language that doesn't exist. And maybe this 00:20:45.890 --> 00:20:49.369 works both ways. Maybe we've already received 00:20:49.369 --> 00:20:52.190 messages like this and we didn't recognize them. 00:20:52.329 --> 00:20:56.049 We've detected fleeting, unexplained radio bursts, 00:20:56.349 --> 00:21:00.609 like the famous wow signal, and fast radio bursts 00:21:00.609 --> 00:21:03.670 that repeat and vanish. Maybe those are natural, 00:21:04.049 --> 00:21:07.109 or maybe they're messages encoded in forms we 00:21:07.109 --> 00:21:12.509 can't yet decipher. SETI scientist Paul Davies 00:21:12.509 --> 00:21:15.509 once said that an alien transmission might be, 00:21:15.509 --> 00:21:19.069 quote, hidden in plain sight, a pattern so subtle 00:21:19.069 --> 00:21:23.049 we mistake it for noise. And Jill Tarter reminded 00:21:23.049 --> 00:21:26.150 us that if the universe is speaking to us, we 00:21:26.150 --> 00:21:30.410 might not recognize the language. The Arecibo 00:21:30.410 --> 00:21:33.430 message was meant to say something about who 00:21:33.430 --> 00:21:36.829 we were and what we could do. It was an act of 00:21:36.829 --> 00:21:40.390 optimism, a beacon of math and meaning beamed 00:21:40.390 --> 00:21:44.500 into the dark. Even now, more than 50 years later, 00:21:44.700 --> 00:21:47.240 that signal is still traveling outward at the 00:21:47.240 --> 00:21:50.460 speed of light, racing across the space between 00:21:50.460 --> 00:21:54.880 stars. Long after our voices fade, that signal 00:21:54.880 --> 00:21:58.259 will keep going, like a perfectly preserved artifact 00:21:58.259 --> 00:22:02.460 of curiosity and intelligence. Maybe someday 00:22:02.460 --> 00:22:05.119 someone will catch it, maybe they'll rearrange 00:22:05.119 --> 00:22:08.099 the bits and see the shape of a human, and maybe 00:22:08.099 --> 00:22:10.920 they'll wonder who we were. or maybe they'll 00:22:10.920 --> 00:22:14.940 see nothing at all. The Arecibo message was just 00:22:14.940 --> 00:22:18.660 the beginning. Since 1974, we've sent a handful 00:22:18.660 --> 00:22:21.819 of others, each one a new experiment in interstellar 00:22:21.819 --> 00:22:27.180 communication. In 1983, Japan's message to Altair 00:22:27.180 --> 00:22:29.779 carried digital greetings toward a nearby bright 00:22:29.779 --> 00:22:35.759 star. In 1999 and 2003, the Cosmic Call 1 &2 00:22:35.759 --> 00:22:39.539 projects transmitted more elaborate self -describing 00:22:39.539 --> 00:22:44.759 data sets toward multiple Sun -like stars. Later 00:22:44.759 --> 00:22:49.000 came the Teenage Message in 2001, a musical broadcast 00:22:49.000 --> 00:22:53.339 created by Russian students, and NASA's 2008 00:22:53.339 --> 00:22:56.740 Across the Universe signal, which beamed a Beatles 00:22:56.740 --> 00:23:10.750 song toward Polaris. That same year and into 00:23:10.750 --> 00:23:14.630 2009, messages such as a message from Earth and 00:23:14.630 --> 00:23:17.910 hello from Earth targeted the potentially habitable 00:23:17.910 --> 00:23:22.730 world Gliese 581c, carrying thousands of short 00:23:22.730 --> 00:23:26.730 notes from people around the globe. Each attempt 00:23:26.730 --> 00:23:30.130 has been part scientific demonstration and part 00:23:30.130 --> 00:23:33.519 act of faith. Whether these signals ever reach 00:23:33.519 --> 00:23:36.680 another mind is unknown, but together they form 00:23:36.680 --> 00:23:40.259 a faint chorus of intent. Evidence that at least 00:23:40.259 --> 00:23:44.160 once and then again and again a small species 00:23:44.160 --> 00:23:47.420 on a small planet looked up and tried to say 00:23:47.420 --> 00:24:08.880 hello to the universe. It's funny how the things 00:24:08.880 --> 00:24:12.640 we love sometimes circle back and meet each other. 00:24:13.119 --> 00:24:17.279 For me, astronomy, ham radio, and music always 00:24:17.279 --> 00:24:20.660 felt like separate pursuits. One is about the 00:24:20.660 --> 00:24:24.460 stars, one is about radio waves, and one is about 00:24:24.460 --> 00:24:27.599 sound. But when you start listening closely, 00:24:27.880 --> 00:24:30.559 you realize they're all part of the same language. 00:24:31.599 --> 00:24:34.359 I had a lot of fun making this one, but producing 00:24:34.359 --> 00:24:36.960 episodes like this requires a good bit of time 00:24:36.960 --> 00:24:40.380 and even more caffeine. If you found it interesting, 00:24:40.559 --> 00:24:42.640 please share it with a friend who might enjoy 00:24:42.640 --> 00:24:45.400 it. The easiest way to do that is by sending 00:24:45.400 --> 00:24:49.839 folks to our website, StarTrails .Show. And if 00:24:49.839 --> 00:24:52.000 you want to support the show, use the link on 00:24:52.000 --> 00:24:54.740 the site to buy me a coffee. It really helps. 00:24:55.759 --> 00:24:59.400 Be sure to follow us on Blue Sky and YouTube. 00:24:59.960 --> 00:25:02.299 Links are in the show notes. Until we meet again 00:25:02.299 --> 00:25:04.859 beneath the stars, clear skies everyone.