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Sunspots, debris and/or a distant cloud are not completely ruled out: https://arxiv.org/abs/1608.01316 https://arxiv.org/abs/1608.01316 Wiki: The leading hypo

by singularity2001 10y ago

Sunspots, debris and/or a distant cloud are not completely ruled out: https://arxiv.org/abs/1608.01316 https://arxiv.org/abs/1608.01316 Wiki: The leading hypothesis, based on a lack of observed infrared light, is that of a swarm of cold, dusty comet fragments in a highly eccentric orbit.[12][13][14] Many small masses in "tight formation" orbiting the star have also been proposed.[9] The changes in brightness could be signs of activity associated with intelligent extraterrestrial life building a Dyson swarm.[9][15][16][17] The SETI Institute's initial radio reconnaissance of KIC 8462852, however, found no evidence of technology-related radio signals from the star. https://en.wikipedia.org/wiki/KIC_8462852 https://en.wikipedia.org/wiki/KIC_8462852

CamperBob2 10y ago
Safe to say that a civilization that can build a Dyson structure isn't using any 20th-century coherent modulation types that SETI could detect. SETI is only useful for catching civilizations in the ~100 Earth year-equivalent span between their development of wireless tech and information theory. There's nothing to listen to but white noise after that.
- Zardoz84 10y ago
  SETI have some dubious criteria like that an alien civilization would emit at Hydrogen resonance frequency because is a universal constant. Any HAM radio operator or telecommunication engineer know well how bad is trying to emit anything on Hydrogen band because is full of natural noise.
  - kirykl 10y ago
    I understand the hydrogen line to be used tho because the noise is constant and any deviation or pattern could be easily identifiable
    - machrider 10y ago
      The problem with noise is that your signal has to be bigger than the noise in order to be intelligible. Preferably you'd find a channel with less noise, not more.
      - dredmorbius 10y ago
        Your signal doesn't have to be bigger than the noise. But your effective channel bandwidth is limited by the signal/noise ratio: <quote> Shannon’s channel capacity criteria for noisy channels Given a communication channel with bandwidth of B Hz. and a signal-to-noise ratio of S/N, where S is the signal power and N is the noise power, Shannon’s formulae for the maximum channel capacity C of such a channel is C = B log (1 + S/N) (log is to base 2) For example, for a channel with bandwidth of 3 KHz and with a S/N value of 1000, like that of a typical telephone line, the maximum channel capacity is C = 3000 * log (1 + 1000) = 30000 bps (approx.) </quote> http://computernetworkingsimplified.com/physical-layer/relationship-bandwidth-data-rate-channel-capacity/ http://computernetworkingsimplified.com/physical-layer/relat... On SETI's use of the Hydrogen line: <quote> The hydrogen line (1420.40575 MHz) is the precession frequency of neutral hydrogen atoms, the most abundant substance in space. It happens to fall in the quietest part of the radio spectrum, what's known as the Microwave Window. Although there may not seem to be a lot of loose hydrogen atoms about (there's perhaps one per cubic centimeter of interstellar space), the interstellar medium contains a lot of cubic centimeters. So these individual atoms chirping away at 1420 MHz make a powerful chorus, which is readily detected by even small radio telescopes. </quote> http://www.setileague.org/askdr/hydrogen.htm http://www.setileague.org/askdr/hydrogen.htm At 1420 MHz, even with an S/N of 1/1000, you'd have about 2,048 kbaud channel, if I'm doing my maths right. Given that an intentional signal could be highly directional, this seems possible.
- seventytwo 10y ago
  This is speculation. There are all kinds of examples we have of "ancient" technology that are still in everyday use today - knives, for example. There's no reason to think that something else would abandon using EM as a transfer of communication.
  - CamperBob2 10y ago
    That's not what I said. Tune a general-coverage receiver to the frequency of an HDTV station, and what you hear is what the SETI folks will hear, whether there's a signal there or not.
    - TeMPOraL 10y ago
      Also, from what I understand, the last several decades of our radio history were spent optimizing everything so that signals keep as much to the ground as possible - emitting TV into space is wasting money.
  - snowwrestler 10y ago
    Think about how many people get their TV via a wire today, instead of via antenna. A lot of people get satellite TV, which is a strong signal but pointed toward the ground. And even the terrestrial radio and TV stations still broadcasting are strictly power-limited to reduce geographic overlap. Most long-distance communication travels over wires too--everyone uses fiber backhaul. Phones and computers use EM (cellular, WiFi, Bluetooth) but the range is very short, so the signal power is far too low to report us to the universe. On top of that, most entertainment and communications signals today are digital, and many are encrypted. It's going to sound like noise to a receiver that doesn't know the encoding and/or have the encryption key. The most powerful space-facing EM emissions we make today, as a species, is probably RADAR, not a form of communications.
    - dragonwriter 10y ago
      > Think about how many people get their TV via a wire today, instead of via antenna. A lot of people get satellite TV, which is a strong signal but pointed toward the ground. Since I don't think its coming from manned satellites where the content is generated, I'm pretty sure there is a space-facing signal involved in satellite TV as well as a ground-facing signal.

CamperBob2 10y ago

Safe to say that a civilization that can build a Dyson structure isn't using any 20th-century coherent modulation types that SETI could detect. SETI is only useful for catching civilizations in the ~100 Earth year-equivalent span between their development of wireless tech and information theory. There's nothing to listen to but white noise after that.

Zardoz84 10y ago
SETI have some dubious criteria like that an alien civilization would emit at Hydrogen resonance frequency because is a universal constant. Any HAM radio operator or telecommunication engineer know well how bad is trying to emit anything on Hydrogen band because is full of natural noise.
- kirykl 10y ago
  I understand the hydrogen line to be used tho because the noise is constant and any deviation or pattern could be easily identifiable
  - machrider 10y ago
    The problem with noise is that your signal has to be bigger than the noise in order to be intelligible. Preferably you'd find a channel with less noise, not more.
    - dredmorbius 10y ago
      Your signal doesn't have to be bigger than the noise. But your effective channel bandwidth is limited by the signal/noise ratio: <quote> Shannon’s channel capacity criteria for noisy channels Given a communication channel with bandwidth of B Hz. and a signal-to-noise ratio of S/N, where S is the signal power and N is the noise power, Shannon’s formulae for the maximum channel capacity C of such a channel is C = B log (1 + S/N) (log is to base 2) For example, for a channel with bandwidth of 3 KHz and with a S/N value of 1000, like that of a typical telephone line, the maximum channel capacity is C = 3000 * log (1 + 1000) = 30000 bps (approx.) </quote> http://computernetworkingsimplified.com/physical-layer/relationship-bandwidth-data-rate-channel-capacity/ http://computernetworkingsimplified.com/physical-layer/relat... On SETI's use of the Hydrogen line: <quote> The hydrogen line (1420.40575 MHz) is the precession frequency of neutral hydrogen atoms, the most abundant substance in space. It happens to fall in the quietest part of the radio spectrum, what's known as the Microwave Window. Although there may not seem to be a lot of loose hydrogen atoms about (there's perhaps one per cubic centimeter of interstellar space), the interstellar medium contains a lot of cubic centimeters. So these individual atoms chirping away at 1420 MHz make a powerful chorus, which is readily detected by even small radio telescopes. </quote> http://www.setileague.org/askdr/hydrogen.htm http://www.setileague.org/askdr/hydrogen.htm At 1420 MHz, even with an S/N of 1/1000, you'd have about 2,048 kbaud channel, if I'm doing my maths right. Given that an intentional signal could be highly directional, this seems possible.
seventytwo 10y ago
This is speculation. There are all kinds of examples we have of "ancient" technology that are still in everyday use today - knives, for example. There's no reason to think that something else would abandon using EM as a transfer of communication.
- CamperBob2 10y ago
  That's not what I said. Tune a general-coverage receiver to the frequency of an HDTV station, and what you hear is what the SETI folks will hear, whether there's a signal there or not.
  - TeMPOraL 10y ago
    Also, from what I understand, the last several decades of our radio history were spent optimizing everything so that signals keep as much to the ground as possible - emitting TV into space is wasting money.
- snowwrestler 10y ago
  Think about how many people get their TV via a wire today, instead of via antenna. A lot of people get satellite TV, which is a strong signal but pointed toward the ground. And even the terrestrial radio and TV stations still broadcasting are strictly power-limited to reduce geographic overlap. Most long-distance communication travels over wires too--everyone uses fiber backhaul. Phones and computers use EM (cellular, WiFi, Bluetooth) but the range is very short, so the signal power is far too low to report us to the universe. On top of that, most entertainment and communications signals today are digital, and many are encrypted. It's going to sound like noise to a receiver that doesn't know the encoding and/or have the encryption key. The most powerful space-facing EM emissions we make today, as a species, is probably RADAR, not a form of communications.
  - dragonwriter 10y ago
    > Think about how many people get their TV via a wire today, instead of via antenna. A lot of people get satellite TV, which is a strong signal but pointed toward the ground. Since I don't think its coming from manned satellites where the content is generated, I'm pretty sure there is a space-facing signal involved in satellite TV as well as a ground-facing signal.