6 ms·

Energy is very abundant by E = mc^2, so what we consider "wasting energy" they may not even consider. The average web page is bigger than the original DOOM dow

Energy is very abundant by E = mc^2, so what we consider "wasting energy" they may not even consider. The average web page is bigger than the original DOOM download, about 2/3 the size of War and Peace. In an era before Gutenberg, when monks copied books my hand, I wonder if anybody mused that nobody would "waste" the equivalent of 750 pages to communicate "please log in using your email and password."

saagarjha 8y ago
You need to consider that you're sending a message over millions of light years. You'd need a a power output comparable to a star to be visible across that distance if you didn't focus your message (because, obviously, stars themselves do it!)
- dogma1138 8y ago
  If you want to do it you might as well use the star itself it won’t be that hard to encode a message into the light emanating from the star itself you only need a sufficiently large polarizer or anything else capable of modulating the light coming form the star. Any civilization that would need to communicate even across a few 100 light years would be capable of doing so.
  - bardworx 8y ago
    I’m totally ignorant in this so my question could be half baked but what exactly are you saying? By polarizing light, do you mean that a device would intercept the photons escaping from the sun and then changing their wavelength to encode a message similar to Morse code? Or do you mean something else entirely? Edit: a word
    - dogma1138 8y ago
      A polarizer only allows light of certain polarity (the "direction" the waveform oscillates, think sunglasses or 3D glasses, or the polariser in your LCD screen) to pass through. https://en.wikipedia.org/wiki/Polarization_(waves) https://en.wikipedia.org/wiki/Polarization_(waves) But it doesn't have to be polarization just any easy modulation of the light, polarization is just easy to do since all you need is a huge polarizer and a few reaction wheels. Think about planetary transitions; we can detect those quite easily this is how we find exoplanets these days, in fact we can fairly accurately identify the composition of the planet's atmosphere and the atmosphere is a fairly thin slice of the entire planet's silhouette. So the only thing you need to do is to position a sufficiently big object it doesn't have to be even that big (still huge in our scale but something in the range of 100's or even 1000's of kilometers across would likely be sufficient the radius of the earth is only 6300KM~ and we can detect planets smaller than the earth AFAIK, and it can be as thin as a solar sail and considering we already build satellites with antenna that unfold to the size of a few football fields it might be possible even with our current level of technology or something not that far off) because you take advantage of the distance between planetary systems that object needs to be able to modulate the light it can be polarization, abstraction, color filtering. To put it simply make a huge ass thin TFT LCD let the sun act as a backlight and put it in a stelar synchronous orbit from the vantage point of the star system you want to communicate with so it would always appear in line between it and your local star and blink your messages away. If you want to go for the golden star then build a huge ring which also is capable of acting like lense this can allow you to have a communication array which can also direct the signal in a relative narrow beam.
      - bardworx 8y ago
        Thank you for that reply. Makes a lot of sense.
      - pilsetnieks 8y ago
        It doesn't even have to be that huge if it's further away from the star.
        NegativeLatency 8y ago
        Then you’re back into having a narrow transmission beam
    - 2muchcoffeeman 8y ago
      A polariser filters light whose electric field is oriented in a particular direction. Like modern 3D glasses.
    - saagarjha 8y ago
      > intercept the protons escaping from the sun Minor typo: you mean "photons".
      - bardworx 8y ago
        Thanks. Corrected.
      - taneq 8y ago
        Solar wind too though.
  - GW150914 8y ago
    If you haven’t read Liu Cixin’s Rememberance of Earth’s Past trilogy you might really enjoy it.
  - kbenson 8y ago
    That's an interesting idea (and something touched on in The Dark Forest[1], which is pretty good just for a peek into hard sci-fi through the lens of another culture). How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away, if you positioned yourself towards the edge of the solar system? Is this cost effective, or any faster than using targeted EM? 1: https://en.wikipedia.org/wiki/The_Dark_Forest https://en.wikipedia.org/wiki/The_Dark_Forest
    - dexen 8y ago
      >How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away Jupiter-sized is good enough for some 3700 light-years with 2016-era technology [1]. We know because that's one of the current methods of detecting exoplanets [2]. -- [1] http://www.sci-news.com/astronomy/kepler-1647b-circumbinary-planet-03945.html http://www.sci-news.com/astronomy/kepler-1647b-circumbinary-... [2] https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Transit_photometry https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanet...
      - dogma1138 8y ago
        On the other hand Kepler 37b is only slightly bigger than the moon and its 200 l/y away. Planetary transistion detection isn’t just a question of size (of both the star and the planet) and it’s orbit but also of alignment of the orbit of the planet, the orbit of earth and the two systems. Now with a predetermined communication array the alignment isn’t a problem more so you can use a light shield at the receptor similar to StarShade which will be used to block the light from the star allowing Kepler to image the planets directly to block the majority of the light from the star which would reduce the required size of your transmitter further. It’s quite likely that over a distance of even a few 100 light years with a modulator as small as a few 100 km across might be sufficient.
  - codebje 8y ago
    The problem with communicating across even a few hundred light years is that everybody's bored and gone to do something else before the response arrives. You'd need a spectacularly static civilisation to engage in any meaningful communication over the timespans involved.
    - wheels 8y ago
      That's a very young-civilization perspective. 100 years seems like a long time to us because it's approximately 1% of the age of our civilization. But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan. Also keep in mind than until recently on earth we used transmission mechanisms for long-on-earth distances that were closer to the order of magnitude of 100-year transmission time (a few months) than to present transmission time (a few milliseconds).
      - fauigerzigerk 8y ago
        >But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan. I don't know if it is possible for a civilization to connect the past to the present over such long periods of time. The individuals in each generation would have to pick up, use and pass on all the information that came before. Our capacity to take past information into account, individually and collectively, is very limited, even if it gets stored somewhere. We can see that in many debates on here where arguments of the past are repeated many times over without younger participants having any awareness of what's been said before. We can compensate for that to some degree by continuously retelling old stories. But relearning old stuff necessarily competes with new information for our limited mental capacity and so old information inevitable degrades over time. Even religions, where there is a strong emotional incentive to retell old stories, are struggling mightily with even understanding what the original authors meant by the words they used and how to apply any of it to the current situation. I think for a civilization to retain its collective memory over much longer periods of time requires completely different individuals. It requires individuals that are able to grow their mental capacity at the same pace as the amount of accumulated information grows. If you consider the combinatoric explosion, this is unimaginable in a biological organism based on evolution and ultimately even in an AI.
  - jfries 8y ago
    Seems to me that the size of the star would be a problem. Assuming the process of actually building stuff large enough to cover a star is solved, how do you control the polarizer to get any reasonable bandwidth? The light emitted from one side of the star will be shifted in time relative to the light emitted from the other side, in anything other than a very narrow beam. Targets outside of this beam will not really receive much of a signal due to interference.
  - varjag 8y ago
    The diameter of Sun is 4.5 light-seconds. This is the lower bound for Sun-sized polarizer switching, as whatever switching process is it has to propagate at below speed of light. Which gives a really poor communication bandwidth even compared to a human Morse operator. Radio is much better bet.
    - ithkuil 8y ago
      Never underestimate the bandwidth of a truckload of hard disks. Latency hardly matters when the majority of the lag is the 100 light year leg: you first spread out your whole message to the surface of the filter with a high bandwidth distribution medium. Then each section of the filter switches in sync, encoding the message without relying on a real-time input from a central location light seconds away
      - rurban 8y ago
        what you are saying could also be: other civilizations would do the same as we do. send small unmanned drones into space, and not just signals. they are much slower, but allow much more information and better reaction time, if the onboard logic does that. and they are not mistaken for something else, as in this case.
      - resters 8y ago
        Is it necessary to use the star one is orbiting around? Why not use an array of smaller polarizers that can be modulated when they block the path of a bright but less adjacent star’s light to the recipient?
    - sjruckle 8y ago
      Can't you delay the signal sent to the center-parts of the polarizer relative to the edge? I think the panel would appear to switch all at once to somebody far away. Seems like this would increase the bandwidth.
      - kabdib 8y ago
        Problem is, a star is curved, with the limb being over two light-seconds farther away from an observer than the center. Sure, you can switch the whole surface of the star as fast as you like, with bandwidth limited by how accurately you can synchronize the switching components. An advanced civilization might be pretty good with attosecond-level stuff, but the signal gets spread out over seconds regardless of the synchronization superscience you apply. You can phase the switches and "aim" the star's signal at a point in the sky. Lower-frequency modulation can get signals to observers not on the direct line, at a lower bandwidth, and you can probably sweep these. Worst case you can blink the whole affair slowly; a star with a five second light curve is going to be pretty interesting.
  - logfromblammo 8y ago
    And I just imagined an Elsevier-like alien company controlling the broadcast bitstream for an entire star. "...mit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol Sys..."
  - abathur 8y ago
    I had this rough question (i.e., while entertaining causes as elaborate as a Dyson sphere, considering that a star might intentionally be used to send a low-information rotating signal like a lighthouse or signal/Morse lamp out along a plane) after the news about Tabby's star broke. I.e., I emailed it to Tabetha (no response; didn't expect one).
- hyc_symas 8y ago
  This is precisely why using neutrinos would be an attractive idea - the signal could travel over extremely long distances with very little diffusion/attenuation. (I.e., as long as you have a narrowly focused beam, to control dispersal, the beam itself won't be weakened by any intervening debris.)
rbanffy 8y ago
> Energy is very abundant by E = mc^2 While we can expect a sufficiently advanced civilization to be in control of vast sources of energy, we need to consider losses, because nothing can be 100% energy-efficient. If sending data to the next node of your intergalacticnet requires you to deal with a Hiroshima per second of waste heat, yours is not a particularly attractive communication channel. And, unless you have a very large heat exchanger, you are vulnerable to side-channel attacks where a third party can detect the heat you need to dissipate.
dalore 8y ago
Perhaps instead of waste they are worried about, it's detection. Instead of broadcasting everywhere and letting all the swarm devouring aliens know where you are, doing a highly focused beam is far less likely to get detected.
- Thiez 8y ago
  Surely any species that manages interstellar travel will have a much easier time growing sentient beings to eat on their own planet(s), rather than going to other solar systems, lifting the people there out of their gravity well into space, and consuming them?

saagarjha 8y ago

You need to consider that you're sending a message over millions of light years. You'd need a a power output comparable to a star to be visible across that distance if you didn't focus your message (because, obviously, stars themselves do it!)

dogma1138 8y ago
If you want to do it you might as well use the star itself it won’t be that hard to encode a message into the light emanating from the star itself you only need a sufficiently large polarizer or anything else capable of modulating the light coming form the star. Any civilization that would need to communicate even across a few 100 light years would be capable of doing so.
- bardworx 8y ago
  I’m totally ignorant in this so my question could be half baked but what exactly are you saying? By polarizing light, do you mean that a device would intercept the photons escaping from the sun and then changing their wavelength to encode a message similar to Morse code? Or do you mean something else entirely? Edit: a word
  - dogma1138 8y ago
    A polarizer only allows light of certain polarity (the "direction" the waveform oscillates, think sunglasses or 3D glasses, or the polariser in your LCD screen) to pass through. https://en.wikipedia.org/wiki/Polarization_(waves) https://en.wikipedia.org/wiki/Polarization_(waves) But it doesn't have to be polarization just any easy modulation of the light, polarization is just easy to do since all you need is a huge polarizer and a few reaction wheels. Think about planetary transitions; we can detect those quite easily this is how we find exoplanets these days, in fact we can fairly accurately identify the composition of the planet's atmosphere and the atmosphere is a fairly thin slice of the entire planet's silhouette. So the only thing you need to do is to position a sufficiently big object it doesn't have to be even that big (still huge in our scale but something in the range of 100's or even 1000's of kilometers across would likely be sufficient the radius of the earth is only 6300KM~ and we can detect planets smaller than the earth AFAIK, and it can be as thin as a solar sail and considering we already build satellites with antenna that unfold to the size of a few football fields it might be possible even with our current level of technology or something not that far off) because you take advantage of the distance between planetary systems that object needs to be able to modulate the light it can be polarization, abstraction, color filtering. To put it simply make a huge ass thin TFT LCD let the sun act as a backlight and put it in a stelar synchronous orbit from the vantage point of the star system you want to communicate with so it would always appear in line between it and your local star and blink your messages away. If you want to go for the golden star then build a huge ring which also is capable of acting like lense this can allow you to have a communication array which can also direct the signal in a relative narrow beam.
    - bardworx 8y ago
      Thank you for that reply. Makes a lot of sense.
    - pilsetnieks 8y ago
      It doesn't even have to be that huge if it's further away from the star.
      - NegativeLatency 8y ago
        Then you’re back into having a narrow transmission beam
  - 2muchcoffeeman 8y ago
    A polariser filters light whose electric field is oriented in a particular direction. Like modern 3D glasses.
  - saagarjha 8y ago
    > intercept the protons escaping from the sun Minor typo: you mean "photons".
    - bardworx 8y ago
      Thanks. Corrected.
    - taneq 8y ago
      Solar wind too though.
- GW150914 8y ago
  If you haven’t read Liu Cixin’s Rememberance of Earth’s Past trilogy you might really enjoy it.
- kbenson 8y ago
  That's an interesting idea (and something touched on in The Dark Forest[1], which is pretty good just for a peek into hard sci-fi through the lens of another culture). How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away, if you positioned yourself towards the edge of the solar system? Is this cost effective, or any faster than using targeted EM? 1: https://en.wikipedia.org/wiki/The_Dark_Forest https://en.wikipedia.org/wiki/The_Dark_Forest
  - dexen 8y ago
    >How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away Jupiter-sized is good enough for some 3700 light-years with 2016-era technology [1]. We know because that's one of the current methods of detecting exoplanets [2]. -- [1] http://www.sci-news.com/astronomy/kepler-1647b-circumbinary-planet-03945.html http://www.sci-news.com/astronomy/kepler-1647b-circumbinary-... [2] https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Transit_photometry https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanet...
    - dogma1138 8y ago
      On the other hand Kepler 37b is only slightly bigger than the moon and its 200 l/y away. Planetary transistion detection isn’t just a question of size (of both the star and the planet) and it’s orbit but also of alignment of the orbit of the planet, the orbit of earth and the two systems. Now with a predetermined communication array the alignment isn’t a problem more so you can use a light shield at the receptor similar to StarShade which will be used to block the light from the star allowing Kepler to image the planets directly to block the majority of the light from the star which would reduce the required size of your transmitter further. It’s quite likely that over a distance of even a few 100 light years with a modulator as small as a few 100 km across might be sufficient.
- codebje 8y ago
  The problem with communicating across even a few hundred light years is that everybody's bored and gone to do something else before the response arrives. You'd need a spectacularly static civilisation to engage in any meaningful communication over the timespans involved.
  - wheels 8y ago
    That's a very young-civilization perspective. 100 years seems like a long time to us because it's approximately 1% of the age of our civilization. But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan. Also keep in mind than until recently on earth we used transmission mechanisms for long-on-earth distances that were closer to the order of magnitude of 100-year transmission time (a few months) than to present transmission time (a few milliseconds).
    - fauigerzigerk 8y ago
      >But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan. I don't know if it is possible for a civilization to connect the past to the present over such long periods of time. The individuals in each generation would have to pick up, use and pass on all the information that came before. Our capacity to take past information into account, individually and collectively, is very limited, even if it gets stored somewhere. We can see that in many debates on here where arguments of the past are repeated many times over without younger participants having any awareness of what's been said before. We can compensate for that to some degree by continuously retelling old stories. But relearning old stuff necessarily competes with new information for our limited mental capacity and so old information inevitable degrades over time. Even religions, where there is a strong emotional incentive to retell old stories, are struggling mightily with even understanding what the original authors meant by the words they used and how to apply any of it to the current situation. I think for a civilization to retain its collective memory over much longer periods of time requires completely different individuals. It requires individuals that are able to grow their mental capacity at the same pace as the amount of accumulated information grows. If you consider the combinatoric explosion, this is unimaginable in a biological organism based on evolution and ultimately even in an AI.
- jfries 8y ago
  Seems to me that the size of the star would be a problem. Assuming the process of actually building stuff large enough to cover a star is solved, how do you control the polarizer to get any reasonable bandwidth? The light emitted from one side of the star will be shifted in time relative to the light emitted from the other side, in anything other than a very narrow beam. Targets outside of this beam will not really receive much of a signal due to interference.
- varjag 8y ago
  The diameter of Sun is 4.5 light-seconds. This is the lower bound for Sun-sized polarizer switching, as whatever switching process is it has to propagate at below speed of light. Which gives a really poor communication bandwidth even compared to a human Morse operator. Radio is much better bet.
  - ithkuil 8y ago
    Never underestimate the bandwidth of a truckload of hard disks. Latency hardly matters when the majority of the lag is the 100 light year leg: you first spread out your whole message to the surface of the filter with a high bandwidth distribution medium. Then each section of the filter switches in sync, encoding the message without relying on a real-time input from a central location light seconds away
    - rurban 8y ago
      what you are saying could also be: other civilizations would do the same as we do. send small unmanned drones into space, and not just signals. they are much slower, but allow much more information and better reaction time, if the onboard logic does that. and they are not mistaken for something else, as in this case.
    - resters 8y ago
      Is it necessary to use the star one is orbiting around? Why not use an array of smaller polarizers that can be modulated when they block the path of a bright but less adjacent star’s light to the recipient?
  - sjruckle 8y ago
    Can't you delay the signal sent to the center-parts of the polarizer relative to the edge? I think the panel would appear to switch all at once to somebody far away. Seems like this would increase the bandwidth.
    - kabdib 8y ago
      Problem is, a star is curved, with the limb being over two light-seconds farther away from an observer than the center. Sure, you can switch the whole surface of the star as fast as you like, with bandwidth limited by how accurately you can synchronize the switching components. An advanced civilization might be pretty good with attosecond-level stuff, but the signal gets spread out over seconds regardless of the synchronization superscience you apply. You can phase the switches and "aim" the star's signal at a point in the sky. Lower-frequency modulation can get signals to observers not on the direct line, at a lower bandwidth, and you can probably sweep these. Worst case you can blink the whole affair slowly; a star with a five second light curve is going to be pretty interesting.
- logfromblammo 8y ago
  And I just imagined an Elsevier-like alien company controlling the broadcast bitstream for an entire star. "...mit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol Sys..."
- abathur 8y ago
  I had this rough question (i.e., while entertaining causes as elaborate as a Dyson sphere, considering that a star might intentionally be used to send a low-information rotating signal like a lighthouse or signal/Morse lamp out along a plane) after the news about Tabby's star broke. I.e., I emailed it to Tabetha (no response; didn't expect one).
hyc_symas 8y ago
This is precisely why using neutrinos would be an attractive idea - the signal could travel over extremely long distances with very little diffusion/attenuation. (I.e., as long as you have a narrowly focused beam, to control dispersal, the beam itself won't be weakened by any intervening debris.)

rbanffy 8y ago

> Energy is very abundant by E = mc^2 While we can expect a sufficiently advanced civilization to be in control of vast sources of energy, we need to consider losses, because nothing can be 100% energy-efficient. If sending data to the next node of your intergalacticnet requires you to deal with a Hiroshima per second of waste heat, yours is not a particularly attractive communication channel. And, unless you have a very large heat exchanger, you are vulnerable to side-channel attacks where a third party can detect the heat you need to dissipate.

dalore 8y ago

Perhaps instead of waste they are worried about, it's detection. Instead of broadcasting everywhere and letting all the swarm devouring aliens know where you are, doing a highly focused beam is far less likely to get detected.

Thiez 8y ago
Surely any species that manages interstellar travel will have a much easier time growing sentient beings to eat on their own planet(s), rather than going to other solar systems, lifting the people there out of their gravity well into space, and consuming them?