I wrote an article about this same general topic way back in 2007[1], wherein I conducted a thought experiment with an Arecibo observatory traveling away from Earth. I calculated that even mighty Arecibo would be unable to detect Earth's omnidirectional FM radio as far out as Saturn, let alone from another star.

Since that writing, we've lost Arecibo observatory, discovered gobs of exoplanets, started scrutinizing those exoplanets with JWST, and increased our radio sphere radius by another 19 lightyears.

[1] https://www.damninteresting.com/space-radio-more-static-less...

> 1936: Berlin Olympics first major TV broadcast

Bit of a plot point in Sagan's novel (and the movie adaptation):

* https://en.wikipedia.org/wiki/Contact_(novel)

I asked a friend at JPL, if there was a civilization at Alpha Centauri and they were sending out the same types of signals as Earth does today, could we detect those signals at Earth with our current tech?

Answer: No (which the article also mentions in so many words)

WBCQ in Monticello, ME (USA) says it broadcasts to outer space via a modulated laser.

From <http://www.wbcq.com/>: WBCQ’s laser broadcasting service is available to beam your program into outer space via our high-powered, modulated, laser system. So in addition to broadcasting worldwide over shortwave radio, you can transmit into space over our high-powered lasers. It’s a lot of fun. The cost for this service is $50 an hour.

This was portrayed in the film Contact (1997) closely to what's described in this piece (maybe it's in the book too? I haven't read it).

I’d love for this chart to also capture the loudest signals we’ve sent. Surely somebody must have accidentally broadcasted a non-directional megawatt radio signal at some point right?

Actually humm maybe nukes are our brightest non directional transmission?

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.

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.

I was thinking about this a few weeks ago.

Doppler shift would substantially change the wavelength, and frequency too.

Perhaps the number of light years a wave has traveled moving in the same direction that Earth is moving in, would be less distance than the side facing the direction that we are moving away from.

The Earth, and Solar System are always moving in motion; I would imagine doppler shift would also have a significant impact on the success of receiving such transmissions.

Given that we don't receive signals like this from at least some direction in the universe, I feel like we can be relatively certain that once this signal reaches some specific area humanity will be toast.

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.

> What they first received

Shouldn't every cell in this column be the same?

Makes me think of the intro to Contact, which was a really cool “visualization” of this… with Hitler and the 1938 Olympics being the first tv broadcast of strength, which aligns with reality