This site was inspired by the opening of Contact
July 15, 2015 1:47 AM Subscribe
Radio broadcasts leave Earth at the speed of light. Scroll away from Earth and hear how far the biggest hits of the past have travelled. The farther away you get, the longer the waves take to travel there—and the older the music you’ll hear.
Oh to be on Epsilon Eridani and hear Blondie's Call Me for the first time. How exciting would that be.
posted by drnick at 2:30 AM on July 15, 2015
posted by drnick at 2:30 AM on July 15, 2015
Sorry, that's EP Eridani, which I had assumed was an abbreviation for Epsilon Eridani. But then I remembered Epsilon Eridani is only about 10 light years away. But EP Eridani is the proper name and is at 33.86 light year. I just felt I'd better clear that up.
posted by drnick at 3:09 AM on July 15, 2015 [1 favorite]
posted by drnick at 3:09 AM on July 15, 2015 [1 favorite]
This is fantastically well done. If I remember the Contact opening sequence though, it showed that one of the first seriously strong radio signals we emitted was Hitler's speech at the opening of the 1933 Olympics. Is that an urban myth?
posted by Happy Dave at 3:37 AM on July 15, 2015
posted by Happy Dave at 3:37 AM on July 15, 2015
MetaFilter: this site was inspired by the opening of Contact
posted by Fizz at 3:55 AM on July 15, 2015 [2 favorites]
posted by Fizz at 3:55 AM on July 15, 2015 [2 favorites]
I read that radio waves get attenuated very quickly, because science, and there's no way you could pick them up at any sort of interstellar distance. Is this true? Hope me scientists.
posted by Joe in Australia at 4:08 AM on July 15, 2015
posted by Joe in Australia at 4:08 AM on July 15, 2015
From the site's "About" page:
Although Lightyear.fm has radiowaves reaching over 100 lightyears into space, due to the Inverse Square Law of Propagation, any terrestrial radio broadcast would become nothing but background noise just a few light years away from Earth. So take comfort in knowing that all those awesome constellations up there will never hear Rebecca Black.posted by frimble at 4:28 AM on July 15, 2015 [2 favorites]
If I remember the Contact opening sequence though, it showed that one of the first seriously strong radio signals we emitted was Hitler's speech at the opening of the 1933 Olympics. Is that an urban myth?
Well, the speech was certainly not the first ever radio broadcast, of course, but it probably qualifies as one of the first (if not the first) event simultaneously (or close enough to count) broadcast around the world.
posted by Thorzdad at 5:08 AM on July 15, 2015
Well, the speech was certainly not the first ever radio broadcast, of course, but it probably qualifies as one of the first (if not the first) event simultaneously (or close enough to count) broadcast around the world.
posted by Thorzdad at 5:08 AM on July 15, 2015
At 1 million km the path loss is nearly 190 dB.
So basically there could be several "galactic civilizations" within our galaxy all broadcasting full blast for thousands of years from many planets and we'll never have technology to hear any of their sitcoms as it's all noise billions and billions of miles before it gets here.
Feeling cosmically lonely.
posted by sammyo at 5:11 AM on July 15, 2015 [5 favorites]
So basically there could be several "galactic civilizations" within our galaxy all broadcasting full blast for thousands of years from many planets and we'll never have technology to hear any of their sitcoms as it's all noise billions and billions of miles before it gets here.
Feeling cosmically lonely.
posted by sammyo at 5:11 AM on July 15, 2015 [5 favorites]
This is fantastically well done. If I remember the Contact opening sequence though, it showed that one of the first seriously strong radio signals we emitted was Hitler's speech at the opening of the 1933 Olympics. Is that an urban myth?
The Hitler Olympics television broadcast figures prominently in the plot as part of the signal from Vega, but it is not part of the opening sequence.
That opening sequence -- itself inspired by the short film Powers of Ten -- was artfully done and rightfully quite memorable.
posted by Herodios at 5:31 AM on July 15, 2015 [1 favorite]
The Hitler Olympics television broadcast figures prominently in the plot as part of the signal from Vega, but it is not part of the opening sequence.
That opening sequence -- itself inspired by the short film Powers of Ten -- was artfully done and rightfully quite memorable.
posted by Herodios at 5:31 AM on July 15, 2015 [1 favorite]
That opening sequence -- itself inspired by the short film Powers of Ten -- was artfully done and rightfully quite memorable.
Whenever Powers of Ten is brought up, it behooves me to mention that it also inspired the opening and closing shots of The 'Burbs.
Carry on.
posted by doctornecessiter at 5:56 AM on July 15, 2015 [1 favorite]
Whenever Powers of Ten is brought up, it behooves me to mention that it also inspired the opening and closing shots of The 'Burbs.
Carry on.
posted by doctornecessiter at 5:56 AM on July 15, 2015 [1 favorite]
we're probably safe until "Inna Gadda Da Vida" gets there.
posted by quonsar II: smock fishpants and the temple of foon at 7:02 AM on July 15, 2015 [1 favorite]
posted by quonsar II: smock fishpants and the temple of foon at 7:02 AM on July 15, 2015 [1 favorite]
Yeah, sammyo, but look on the bright side. If their sitcoms are as bad as some of ours, we won't have to watch them.
posted by Anne Neville at 7:08 AM on July 15, 2015
posted by Anne Neville at 7:08 AM on July 15, 2015
I knew SETI was a waste of time and money.
Just because our casual transmissions dissipate quickly doesn't mean communications can't purposefully be made to go farther, especially if it has more power and is directed and narrowband.
posted by vacapinta at 7:08 AM on July 15, 2015 [2 favorites]
Just because our casual transmissions dissipate quickly doesn't mean communications can't purposefully be made to go farther, especially if it has more power and is directed and narrowband.
posted by vacapinta at 7:08 AM on July 15, 2015 [2 favorites]
Given a 100 kW ERP the signal would be around -110 dBm from a dipole. This would be near the noise floor of a receiver.
Assuming a terrestrial level of receiver technology.
posted by quonsar II: smock fishpants and the temple of foon at 7:14 AM on July 15, 2015
Assuming a terrestrial level of receiver technology.
posted by quonsar II: smock fishpants and the temple of foon at 7:14 AM on July 15, 2015
At 1 million km the path loss is nearly 190 dB. Given a 100 kW ERP the signal would be around -110 dBm from a dipole. This would be near the noise floor of a receiver. This distance is a mere 1/10,000,000 of a light year and a matter of light seconds.
New Horizons is currently about 5 billion kilometers away (4.5 light-hours) and has a transmit power of 12 Watts. We receive it just fine.
posted by rocket88 at 7:31 AM on July 15, 2015 [2 favorites]
New Horizons is currently about 5 billion kilometers away (4.5 light-hours) and has a transmit power of 12 Watts. We receive it just fine.
posted by rocket88 at 7:31 AM on July 15, 2015 [2 favorites]
I do hope aliens have no ears and communicate only telepathically, because most of those (until the late 90s, when the sound started to break on my computer) would make an extinction event sized attack a fair retribution.
posted by lmfsilva at 7:45 AM on July 15, 2015
posted by lmfsilva at 7:45 AM on July 15, 2015
Oddly enough, I just watched "Contact" again last night and was, for the first time, stuck by the inaccuracy of the opening sequence which has music from decades ago (relative to "film present day") playing mere light minutes and hours from earth.
Also struck by the fact that the image of the eye used in the opening titles of the Neil deGrasse Tyson "Cosmos" seems to have been a direct lift from "Contact."
posted by Insert Clever Name Here at 8:00 AM on July 15, 2015
Also struck by the fact that the image of the eye used in the opening titles of the Neil deGrasse Tyson "Cosmos" seems to have been a direct lift from "Contact."
posted by Insert Clever Name Here at 8:00 AM on July 15, 2015
This site was inspired by the opening of Contact
And like many media constructs drawing "inspiration" from another source, it merely apes the format without putting much thought into it. It seems to cycle through a short list of songs from each year with no real attempt at making any effort to ensure we do not hear the same song at three different points. And the curation is slipshod at best: in 1979 I was startled to hear a 2013 song, apparently dropped in because the later song's title contains a word that appears in the earlier artist's name. Well, then.
Bummer. This is a fun notion, but poorly executed.
posted by ricochet biscuit at 8:17 AM on July 15, 2015
And like many media constructs drawing "inspiration" from another source, it merely apes the format without putting much thought into it. It seems to cycle through a short list of songs from each year with no real attempt at making any effort to ensure we do not hear the same song at three different points. And the curation is slipshod at best: in 1979 I was startled to hear a 2013 song, apparently dropped in because the later song's title contains a word that appears in the earlier artist's name. Well, then.
Bummer. This is a fun notion, but poorly executed.
posted by ricochet biscuit at 8:17 AM on July 15, 2015
That said, there are some funny -- perhaps happenstance -- juxtapositions: clicking on 50 years ago, I caught The Monkees singing "I couldn't leave her if I tried..." fading smoothly into the Stones with, "and I try, and I try..."
posted by ricochet biscuit at 8:23 AM on July 15, 2015 [1 favorite]
posted by ricochet biscuit at 8:23 AM on July 15, 2015 [1 favorite]
So Space Truckin' is hitting Wolf 497 about now. Cool.
posted by TedW at 8:33 AM on July 15, 2015 [1 favorite]
posted by TedW at 8:33 AM on July 15, 2015 [1 favorite]
It's a fun thing.
Couple of points - only radio signals above around 10 MHz escape the ionosphere and shortwave broadcasting didn't reallly get going until the mid-late 1920s, so it's unlikely there'd be much music to pick up before those years.
As for 'can you hear it?', well, that depends. Radio engineers work that out through a link budget, which is a simple equation where you add up all of the things that boost a signal and all that degrade it (in decibels), and end up with a single figure that shows how energy is left for a particular channel when you put so much in.
Lots of things affect a link budget, but traditionally its the power of the transmitter, the loss of the feed line to the antenna, the gain (if any) of the transmit antenna, the loss due to propagation across the path (dependent on many things, primarily distance), the gain (if any) of the receive antenna, the loss of the feed line to the receiver and the gain of the receiver itself. All these components also introduce noise, so you do the sums and end up with an idea of how much energy from the signal is present compared to how much energy from noise.
Antennas can have gain, so a big dish effectively amplifies signals on transmission and reception, at the expense of constraining the energy sent or received into a narrower beam. The narrower the beam, the stronger the signal. This is good and bad, depending on what you want to do.
These days, it's more complicated because you can add processing gain, where you manipulate the signal and spread it out in time or space (or both), adding various types of encoding and error correction that counteract noise. If you watched the New Horizons 'phone home' event, you'll have heard 'carrier lock' when they got the raw signal, and 'symbol lock', when they started to decode the way the data had been manipulated. So it's very possible, these days, to have a perfectly usable signal that is weaker than noise. (At this point you sort of get into Shannon and Nyquist and Viterbi and really clever maths... but that's another story.)
However, not much of this helps if you're trying to receive a plain old broadcast signal. Perhaps the best way is to visualise it is geometrically. Say you need a 20cm long telescopic whip on your radio to pick up MeFi Classic FM - "All Beefheart, All The Time" - from the transmitter 10km away.
Imagine that the signal starts as a point on the transmitter and expands as a sphere as it rushes out through space, like the old RKO Radio Pictures logo You'll be intercepting the energy at the surface of that sphere as it zooms past you - the antenna is getting the electrons in its metal jiggled around as they absorb the energy from the radio photons, which generates a tiny voltage, which the rest of the radio amplifies.
Your antenna has a area of, say 20cm2. The sphere of radio energy from the transmitter has an area 4 x Pi x R squared, or around 120 square kilometres. In other words, you need to intercept around 60 billionth of the transmitter power. (Which is pretty amazing, given your radio cost ten bucks)
Let's say you're now at Pluto (why not). The Captain's sphere of influence now has a radius of some 7.6 billion kilometres, or an area of 7x10^20 kilometers. Which means your radio would need an antenna with an effective area of around 22 billion square kilometres. (Which wouldn't work, not as just a chunk of metal, for about ten million reasons. But overlook that. And my maths may be wildly out.)
Which is why we don't do spacecraft communications with broadcast FM technologies, and why New Horizons won't be listening to Shiny Beast (Bat Chain Puller) any time soon.
However, that's the sort of hurdle any sort of interstellar broadcast interception will have to sort out, and while it may be possible to harvest EM energy from volumes of space millions of kilometres across (and maintain phase coherence while dealing with noise), I can't offhand think of how that might be practicable with any technology or physics I know of. Even the biggest dish can only pick up the energy that enters its aperture.
There's one further little lump of joy. The days of having large amounts of power being thrown out into the void on single carrier frequencies are nearing their end. Shortwave broadcasting is nearly dead, TV bands are being repurposed to digital data systems at much lower power, and even radar systems are becoming much less incontinent. We're learning to use energy much more effectively, and anything that depends on picking up the stuff we waste is going to have a much harder time of it. (I know that SETI engineers are working on how to detect that sort of stuff, so it's not game over, but...).
Never say die. The same physics that make it unlikely we'll hear stuff from the Centauri Broadcasting System say it's perfectly possible to engineer links that will work over interstellar distances (my favourite is to use your local star as a gravity lens and park a comsat at the focal point. My second favourite is to modulate fusion processes in your local star via a laser beam...). And we do regularly receive signals from thousands of lightyears across the galaxy from pulsars, so it is possible. It's just a matter of the appropriate engineering...
posted by Devonian at 8:48 AM on July 15, 2015 [15 favorites]
Couple of points - only radio signals above around 10 MHz escape the ionosphere and shortwave broadcasting didn't reallly get going until the mid-late 1920s, so it's unlikely there'd be much music to pick up before those years.
As for 'can you hear it?', well, that depends. Radio engineers work that out through a link budget, which is a simple equation where you add up all of the things that boost a signal and all that degrade it (in decibels), and end up with a single figure that shows how energy is left for a particular channel when you put so much in.
Lots of things affect a link budget, but traditionally its the power of the transmitter, the loss of the feed line to the antenna, the gain (if any) of the transmit antenna, the loss due to propagation across the path (dependent on many things, primarily distance), the gain (if any) of the receive antenna, the loss of the feed line to the receiver and the gain of the receiver itself. All these components also introduce noise, so you do the sums and end up with an idea of how much energy from the signal is present compared to how much energy from noise.
Antennas can have gain, so a big dish effectively amplifies signals on transmission and reception, at the expense of constraining the energy sent or received into a narrower beam. The narrower the beam, the stronger the signal. This is good and bad, depending on what you want to do.
These days, it's more complicated because you can add processing gain, where you manipulate the signal and spread it out in time or space (or both), adding various types of encoding and error correction that counteract noise. If you watched the New Horizons 'phone home' event, you'll have heard 'carrier lock' when they got the raw signal, and 'symbol lock', when they started to decode the way the data had been manipulated. So it's very possible, these days, to have a perfectly usable signal that is weaker than noise. (At this point you sort of get into Shannon and Nyquist and Viterbi and really clever maths... but that's another story.)
However, not much of this helps if you're trying to receive a plain old broadcast signal. Perhaps the best way is to visualise it is geometrically. Say you need a 20cm long telescopic whip on your radio to pick up MeFi Classic FM - "All Beefheart, All The Time" - from the transmitter 10km away.
Imagine that the signal starts as a point on the transmitter and expands as a sphere as it rushes out through space, like the old RKO Radio Pictures logo You'll be intercepting the energy at the surface of that sphere as it zooms past you - the antenna is getting the electrons in its metal jiggled around as they absorb the energy from the radio photons, which generates a tiny voltage, which the rest of the radio amplifies.
Your antenna has a area of, say 20cm2. The sphere of radio energy from the transmitter has an area 4 x Pi x R squared, or around 120 square kilometres. In other words, you need to intercept around 60 billionth of the transmitter power. (Which is pretty amazing, given your radio cost ten bucks)
Let's say you're now at Pluto (why not). The Captain's sphere of influence now has a radius of some 7.6 billion kilometres, or an area of 7x10^20 kilometers. Which means your radio would need an antenna with an effective area of around 22 billion square kilometres. (Which wouldn't work, not as just a chunk of metal, for about ten million reasons. But overlook that. And my maths may be wildly out.)
Which is why we don't do spacecraft communications with broadcast FM technologies, and why New Horizons won't be listening to Shiny Beast (Bat Chain Puller) any time soon.
However, that's the sort of hurdle any sort of interstellar broadcast interception will have to sort out, and while it may be possible to harvest EM energy from volumes of space millions of kilometres across (and maintain phase coherence while dealing with noise), I can't offhand think of how that might be practicable with any technology or physics I know of. Even the biggest dish can only pick up the energy that enters its aperture.
There's one further little lump of joy. The days of having large amounts of power being thrown out into the void on single carrier frequencies are nearing their end. Shortwave broadcasting is nearly dead, TV bands are being repurposed to digital data systems at much lower power, and even radar systems are becoming much less incontinent. We're learning to use energy much more effectively, and anything that depends on picking up the stuff we waste is going to have a much harder time of it. (I know that SETI engineers are working on how to detect that sort of stuff, so it's not game over, but...).
Never say die. The same physics that make it unlikely we'll hear stuff from the Centauri Broadcasting System say it's perfectly possible to engineer links that will work over interstellar distances (my favourite is to use your local star as a gravity lens and park a comsat at the focal point. My second favourite is to modulate fusion processes in your local star via a laser beam...). And we do regularly receive signals from thousands of lightyears across the galaxy from pulsars, so it is possible. It's just a matter of the appropriate engineering...
posted by Devonian at 8:48 AM on July 15, 2015 [15 favorites]
New Horizons is currently about 5 billion kilometers away (4.5 light-hours) and has a transmit power of 12 Watts. We receive it just fine.
New Horizons is not broadcasting. It's providing point-to-point commmunication with a high-gain directional transmitting antenna.
And we know where it is and when it will be transmitting and are awaiting its signals with our own high-gain directional receiving antennas.
And its signal is a set of highly structured packets of data with built-in error checking, specifically designed for the purpose, which go through several layers of decoding (which we know how to do because we designed it) to provide the pictures and telemetry we'll eventually see.
That's very different from randomly overhearing a random signal from a random place in the sky that's only a few db above the noise floor of interstellar space*; which signal employs an encoding scheme (amplitude modulation, frequency modulation, etc.) that you can't predict and aren't familar with, which, if you did figure out how to decode is designed to be perceived as filtered audio of (mostly) spoken languages that you don't know and may or may not be equipped to perceive, and which may or may not bear any relationship to your own natural method of interpersonal communication (that is to say, the being intercepting the signal may not even have ears or a mouth).
------------
* Claude Shannon would like a word.
posted by Herodios at 8:56 AM on July 15, 2015 [2 favorites]
New Horizons is not broadcasting. It's providing point-to-point commmunication with a high-gain directional transmitting antenna.
And we know where it is and when it will be transmitting and are awaiting its signals with our own high-gain directional receiving antennas.
And its signal is a set of highly structured packets of data with built-in error checking, specifically designed for the purpose, which go through several layers of decoding (which we know how to do because we designed it) to provide the pictures and telemetry we'll eventually see.
That's very different from randomly overhearing a random signal from a random place in the sky that's only a few db above the noise floor of interstellar space*; which signal employs an encoding scheme (amplitude modulation, frequency modulation, etc.) that you can't predict and aren't familar with, which, if you did figure out how to decode is designed to be perceived as filtered audio of (mostly) spoken languages that you don't know and may or may not be equipped to perceive, and which may or may not bear any relationship to your own natural method of interpersonal communication (that is to say, the being intercepting the signal may not even have ears or a mouth).
------------
* Claude Shannon would like a word.
posted by Herodios at 8:56 AM on July 15, 2015 [2 favorites]
only radio signals above around 10 MHz escape the ionosphere and shortwave broadcasting didn't reallly get going until the mid-late 1920s, so it's unlikely there'd be much music to pick up before those years.
Part of what's fun about the Contact intro is how it's an indecypherable cacaphony close to Earth (close to now), which gradually thins out to allow you to discern individual messages, until further from Earth (further back in time) we are left with a single CW (morse code) signal sending CQ CQ CQ . . . Hello, I'm on the air, I seek you, I seek you, I seek you . . .
Certainly, it's a bit of artistic license that that lone operator, transmitting in the early days of the twentieth century would be heard in space. Very little RF energy at wavelengths above 200 meters (below 1500 kHz --near the top of the modern AM (USA) broadcast band) get into space.
I am inclined to grant it.
posted by Herodios at 9:13 AM on July 15, 2015 [3 favorites]
Part of what's fun about the Contact intro is how it's an indecypherable cacaphony close to Earth (close to now), which gradually thins out to allow you to discern individual messages, until further from Earth (further back in time) we are left with a single CW (morse code) signal sending CQ CQ CQ . . . Hello, I'm on the air, I seek you, I seek you, I seek you . . .
Certainly, it's a bit of artistic license that that lone operator, transmitting in the early days of the twentieth century would be heard in space. Very little RF energy at wavelengths above 200 meters (below 1500 kHz --near the top of the modern AM (USA) broadcast band) get into space.
I am inclined to grant it.
posted by Herodios at 9:13 AM on July 15, 2015 [3 favorites]
Never say die . . . posted by Devonian
You are Wayne Green and I claim my£5 QSL.
73
posted by Herodios at 9:19 AM on July 15, 2015 [1 favorite]
You are Wayne Green and I claim my
73
posted by Herodios at 9:19 AM on July 15, 2015 [1 favorite]
It would be the act of a complete churl to do anything else, Herodios. And while I have massive amounts of pecksniffian churlishness when it comes to radio in movies, I am not completely thus. Contact has sufficient amounts of gorgeous wireless romance to let me overlook that (and that the first CQ signals were spark-gap noise, plus CQ originally came from the wired telegraph as shorthand for "sécu", from the French word sécurité, meaning "here comes a message to do with operations or a general alert, rather than ordinary traffic".)
I do have issues with Contact, but not with its radio.
(And my callsign begins with G rather than W, but there may be resonances, OM)
posted by Devonian at 9:28 AM on July 15, 2015
I do have issues with Contact, but not with its radio.
(And my callsign begins with G rather than W, but there may be resonances, OM)
posted by Devonian at 9:28 AM on July 15, 2015
That opening sequence -- itself inspired by the short film Powers of Ten -- was artfully done and rightfully quite memorable.
The proportions of distance and time, illustrated by various planets and historical soundbites, were way off, no? As you say, artfully done, compromised by what's readily recognized within the solar system versus the "gaps" of space between our star, its position in the Milky Way and the Milky Way's "position".
posted by lazycomputerkids at 9:28 AM on July 15, 2015
The proportions of distance and time, illustrated by various planets and historical soundbites, were way off, no? As you say, artfully done, compromised by what's readily recognized within the solar system versus the "gaps" of space between our star, its position in the Milky Way and the Milky Way's "position".
posted by lazycomputerkids at 9:28 AM on July 15, 2015
the first CQ signals were spark-gap noise
Yeah, again, artistic license, I suppose. The general cinema audience will immediately recognize CW beeps as such even if they don't know code; genuine spark would sound pretty harsh for the purpose, might not be recognised for what it is in the few seconds it's on.
CQ originally came from the wired telegraph as shorthand for "sécu", from the French word sécurité
Yes, I'm granting myself a bit of artistic license here, too, to inspire the general Metafilter audience.
posted by Herodios at 9:46 AM on July 15, 2015
Yeah, again, artistic license, I suppose. The general cinema audience will immediately recognize CW beeps as such even if they don't know code; genuine spark would sound pretty harsh for the purpose, might not be recognised for what it is in the few seconds it's on.
CQ originally came from the wired telegraph as shorthand for "sécu", from the French word sécurité
Yes, I'm granting myself a bit of artistic license here, too, to inspire the general Metafilter audience.
posted by Herodios at 9:46 AM on July 15, 2015
Eta Boötis is hearing Donna Summer and the Bee Gees. Shake Your Boötis!
(This is a super fun post. Thank you!)
posted by Orange Dinosaur Slide at 10:51 AM on July 15, 2015
(This is a super fun post. Thank you!)
posted by Orange Dinosaur Slide at 10:51 AM on July 15, 2015
Eta Boötis is hearing Donna Summer and the Bee Gees. Shake Your Boötis!
Well, that should make a nice change for him. I'll bet he's getting pretty tired of playing his one hit, "Yaäketi Saäxis" over and over again on the ol' chitlin' orbit.
posted by Herodios at 11:31 AM on July 15, 2015 [1 favorite]
Well, that should make a nice change for him. I'll bet he's getting pretty tired of playing his one hit, "Yaäketi Saäxis" over and over again on the ol' chitlin' orbit.
posted by Herodios at 11:31 AM on July 15, 2015 [1 favorite]
> That's very different from randomly overhearing a random signal from a random place in the sky that's only a few db above the noise floor of interstellar space*; which signal employs an encoding scheme (amplitude modulation, frequency modulation, etc.) that you can't predict and aren't familar with, which, if you did figure out how to decode is designed to be perceived as filtered audio of (mostly) spoken languages that you don't know and may or may not be equipped to perceive, and which may or may not bear any relationship to your own natural method of interpersonal communication (that is to say, the being intercepting the signal may not even have ears or a mouth).
There's something charming to me about the idea of another intelligence aiming a radio telescope at the heavens, picking up a 10MHz signal with a periodic amplitude envelope that widens every second, blip blip blip blip -- some strange pulsar, maybe? -- and then wondering just what in the hell is happening every 60 ticks when the amplitude envelope says "at the tone, two hours, forty-four minutes, coordinated universal time."
posted by Westringia F. at 7:44 PM on July 15, 2015
There's something charming to me about the idea of another intelligence aiming a radio telescope at the heavens, picking up a 10MHz signal with a periodic amplitude envelope that widens every second, blip blip blip blip -- some strange pulsar, maybe? -- and then wondering just what in the hell is happening every 60 ticks when the amplitude envelope says "at the tone, two hours, forty-four minutes, coordinated universal time."
posted by Westringia F. at 7:44 PM on July 15, 2015
While any particular station on Earth will get lost in the noise floor relatively quickly, I learned this summer that the Earth's total brightness in the FM band (roughly 10,000 stations, each roughly 50 kW, so 50 MW) is brighter than the Sun in the part of the spectrum by a factor of about fifty. Also more of the radio energy is emitted parallel to the ground (from vertically-oriented antennas) than vertically. This would make for a very interesting 24-hour modulation in the intensity of radio signals from Earth viewed from elsewhere.
posted by fantabulous timewaster at 2:49 PM on July 16, 2015
posted by fantabulous timewaster at 2:49 PM on July 16, 2015
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posted by justsomebodythatyouusedtoknow at 2:28 AM on July 15, 2015 [2 favorites]