Nice article. I had to go down this rabbit-hole researching my first book. Actual likelihood of anyone actually being able to receive these past a few tens of LY is quite low without very sensitive receivers. Also as another commenter pointed out the window for receiving us is closing as more modern wide-band and spread-spectrum signals are more power efficient, directed, and look much closer to noise than data.
Something that I muse about is that this bubble may indeed be a thin shell. My rationale is that already the bulk of our communications are confined to waveguides -- optical fibers. Our wireless comms continue to be engineered to produce less power and to be almost indistinguishable from noise. Much of our AC power travels along paired wires whose fields cancel one another at the equivalent of an inverse-fourth law or worse. Soon they may all be DC.
The civilizations who are "out there" may only have a narrow time window to pick up our signals. Like we've fashioned a poor man's Dyson sphere.
I think that an atmosphere with measurable oxygen gas is a far longer lasting, pervasive and interesting signal that by itself could prompt investigation.
The oxygen has been here for far longer than us, sometimes at much higher levels.
Earth has been screaming it has a very likely biosphere for at least 500 million to a billion years. To anyone with huge space based telescopes.
So why no visitors? If there had been, we wouldn’t know. Any probes that dropped into our planet any further back than a few tens of thousands of years (and less if they landed in a hot wet region) might be gone by now. They’d have been eaten by corrosion and mechanical erosion and eventually by plate tectonics.
They also likely would have been small, meaning even if they got fossilized we’d have to get super lucky to find one. The energy required to accelerate something to meaningful fractions of light speed and then decelerate at the other side means a probe is probably an orbiter the size of a basketball and then a little drone the size of a golf ball or something.
We might have had dozens or hundreds of little visitors over the last billion years and we’d never know unless we got real lucky.
Flyby missions are also likely due to the physics. The energy for slowing down might instead be spent just going faster to get results faster. The probe just streaks past at 7% the speed of light and takes a bunch of pictures and measurements.
Nice article. I had to go down this rabbit-hole researching my first book. Actual likelihood of anyone actually being able to receive these past a few tens of LY is quite low without very sensitive receivers. Also as another commenter pointed out the window for receiving us is closing as more modern wide-band and spread-spectrum signals are more power efficient, directed, and look much closer to noise than data.
A lot of people think the “great silence” from SETI means something, unfortunately.
A civilization using only low power radio wouldn’t be detectable in the Centauri system.
Something that I muse about is that this bubble may indeed be a thin shell. My rationale is that already the bulk of our communications are confined to waveguides -- optical fibers. Our wireless comms continue to be engineered to produce less power and to be almost indistinguishable from noise. Much of our AC power travels along paired wires whose fields cancel one another at the equivalent of an inverse-fourth law or worse. Soon they may all be DC.
The civilizations who are "out there" may only have a narrow time window to pick up our signals. Like we've fashioned a poor man's Dyson sphere.
I think that an atmosphere with measurable oxygen gas is a far longer lasting, pervasive and interesting signal that by itself could prompt investigation.
The oxygen has been here for far longer than us, sometimes at much higher levels.
chemistry has more reactions than just with oxygen, oxygen alone is a poor indicator of life...
Earth has been screaming it has a very likely biosphere for at least 500 million to a billion years. To anyone with huge space based telescopes.
So why no visitors? If there had been, we wouldn’t know. Any probes that dropped into our planet any further back than a few tens of thousands of years (and less if they landed in a hot wet region) might be gone by now. They’d have been eaten by corrosion and mechanical erosion and eventually by plate tectonics.
They also likely would have been small, meaning even if they got fossilized we’d have to get super lucky to find one. The energy required to accelerate something to meaningful fractions of light speed and then decelerate at the other side means a probe is probably an orbiter the size of a basketball and then a little drone the size of a golf ball or something.
We might have had dozens or hundreds of little visitors over the last billion years and we’d never know unless we got real lucky.
Flyby missions are also likely due to the physics. The energy for slowing down might instead be spent just going faster to get results faster. The probe just streaks past at 7% the speed of light and takes a bunch of pictures and measurements.
> What they first received
Shouldn't every cell in this column be the same?