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A comment on SETI spots dozens of new mysterious signals emanating from distant galaxy. Parent comment

Re:SETI spots dozens of new mysterious signals emanating fro... by jerf on Thursday September 13, 2018 @04:23PM (#17982195)
"Communication by electromagnetic radiation suffers from the fact that the radiation diffuses indiscriminately in all directions."

While lasers technically do not need to be beam-like, I would point out that beam lasers do exist, as well as many other directional effects, as seen in flashlights and such.

It is a bizarre alien race that people are hypothesizing that apparently uses whatzamamagic communication that we currently can't even conceive of, but aren't capable of building the things we already know how to build that can provide very good directionality today. A very particular sort of powerful.

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Re:SETI spots dozens of new mysterious signals emanating fro... by thaumasiotes on Thursday September 13, 2018 @04:28PM (#17982238)
Beam lasers exist and stay narrow on the scale that we use them. They are tighter flashlights. Turn on any flashlight and the rapid diffusion of its light will be extremely apparent.

And I'll note that I responded to the comment "electromagnetic radiation basically has every characteristic you're looking for in a communications medium", with no mention of aliens at all. It is not true that electromagnetic radiation basically has every characteristic you're looking for in a communications medium.

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Re:SETI spots dozens of new mysterious signals emanating fro... by saagarjha on Thursday September 13, 2018 @06:25PM (#17983222)
There is a fundamental difference between a laser and a concentrated flashlight–lasers are coherent while ordinary light is not and cannot be made so no matter how much you focus it.
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Re:SETI spots dozens of new mysterious signals emanating fro... by thaumasiotes on Thursday September 13, 2018 @06:44PM (#17983375)
Lasers still diffuse; they are not fundamentally different in that sense. In the signaling sense of "is the light there or not?", whether it is coherent, or would be coherent if it was there, is not relevant to anything.
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Re:SETI spots dozens of new mysterious signals emanating fro... by saagarjha on Thursday September 13, 2018 @06:57PM (#17983451)
Lasers don't technically "diffuse", they spread out due to diffraction inside the beam itself. So they are much, much easier to better to in a reasonably directed beam.
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