3 ms·

> We should have seen it again when we looked for it 50 times. This is a weird thing to say. If the Wow! Signal were indeed from intelligent life, what’s to sa

> We should have seen it again when we looked for it 50 times. This is a weird thing to say. If the Wow! Signal were indeed from intelligent life, what’s to say it’s not like our own Arecibo Message, which was a one-time transient burst transmission?

sidewndr46 4y ago
When you use a telescope like this, you aren't looking for intentional communications. What you are looking for is emissions unrelated to intergalactic communications. The hypothesis is almost every civilization should have a huge emission pattern all over the practically usable RF spectrum. Just on earth for example, television transmitters are constantly broadcasting a very high power signal on all kinds of different frequencies.
- MontyCarloHall 4y ago
  >Just on earth for example, television transmitters are constantly broadcasting a very high power signal on all kinds of different frequencies. These are isotropic radio emissions, and would not be discernible from background radiation at more than a lightyear or so away from Earth, since its intensity diminishes as the inverse square of distance. >What you are looking for is emissions unrelated to intergalactic communications. The hypothesis is almost every civilization should have a huge emission pattern all over the practically usable RF spectrum. This communication would likely be via directed radio emissions (e.g. the Wow! Signal or Arecibo Message), which we could only pick up if our detector were perfectly aligned with the source at the exact time the transmission arrives. Because of that inverse square law, it would be an enormous waste of power to communicate via isotropic radio emissions.
  - sidewndr46 4y ago
    You're assuming that cosmic background radiation is uniformly distributed. It is not. TV transmissions are most definitely not isotropic for any commercial installation. They use directional antennas to avoid sending power directly down into the earth for example. I'm not even aware of a single commercial radio installation with anything approximating an isotropic pattern.
    - MontyCarloHall 4y ago
      While they may not be perfectly isotropic, they are far from being directional (most TV transmitters are monopoles with uniform azimuthal radiation) and would still not be distinguishable from background radiation (regardless of its distribution) at more than a light year or two away [0]. Highly directional radio emissions an order of magnitude more powerful than the strongest transmitters on Earth would only be visible at approximately 100 light years away [1]. [0] https://physics.stackexchange.com/a/245562 https://physics.stackexchange.com/a/245562 [1] https://arxiv.org/pdf/astro-ph/0610377.pdf https://arxiv.org/pdf/astro-ph/0610377.pdf

sidewndr46 4y ago

When you use a telescope like this, you aren't looking for intentional communications. What you are looking for is emissions unrelated to intergalactic communications. The hypothesis is almost every civilization should have a huge emission pattern all over the practically usable RF spectrum. Just on earth for example, television transmitters are constantly broadcasting a very high power signal on all kinds of different frequencies.

MontyCarloHall 4y ago
>Just on earth for example, television transmitters are constantly broadcasting a very high power signal on all kinds of different frequencies. These are isotropic radio emissions, and would not be discernible from background radiation at more than a lightyear or so away from Earth, since its intensity diminishes as the inverse square of distance. >What you are looking for is emissions unrelated to intergalactic communications. The hypothesis is almost every civilization should have a huge emission pattern all over the practically usable RF spectrum. This communication would likely be via directed radio emissions (e.g. the Wow! Signal or Arecibo Message), which we could only pick up if our detector were perfectly aligned with the source at the exact time the transmission arrives. Because of that inverse square law, it would be an enormous waste of power to communicate via isotropic radio emissions.
- sidewndr46 4y ago
  You're assuming that cosmic background radiation is uniformly distributed. It is not. TV transmissions are most definitely not isotropic for any commercial installation. They use directional antennas to avoid sending power directly down into the earth for example. I'm not even aware of a single commercial radio installation with anything approximating an isotropic pattern.
  - MontyCarloHall 4y ago
    While they may not be perfectly isotropic, they are far from being directional (most TV transmitters are monopoles with uniform azimuthal radiation) and would still not be distinguishable from background radiation (regardless of its distribution) at more than a light year or two away [0]. Highly directional radio emissions an order of magnitude more powerful than the strongest transmitters on Earth would only be visible at approximately 100 light years away [1]. [0] https://physics.stackexchange.com/a/245562 https://physics.stackexchange.com/a/245562 [1] https://arxiv.org/pdf/astro-ph/0610377.pdf https://arxiv.org/pdf/astro-ph/0610377.pdf