My theory is that it encoded the uploaded consciousness of their best minds, along with a compelling argument that the only way to escape our gravity well is to upload our minds via a multigigawatt transmitter, along with instructions on how to build one (except those instructions won't work unless we propagate their signal). It might drive our civilization to the brink of our resource capacity to undertake this project, but it's the only way to propagate ourselves and survive, so what choice would we have?
If one created a physical substrate that neurons could transmit to and from, then embedded it in the brain, you could create consciousness in that substrate. A primitive analogue of this has been done where they attach electrodes to the tongue and fired them in a pattern suggestive of a video feed, eventually the brain started to understand it as another 'sense'.
Should one start brain-interacting directly with a substrate, the substrate could be powered independently and persist after separation. If separation occurred after natural death of the host, you could say that it 'uploaded' it's consciousness to the substrate.
That's just a replay attack. The consciousness is still bound to the cells. No new, unique information is generated without the presence of the cells.
The term "uploaded" is being subjected to special semantics in this case. Consciousness is not transferred over to the receiver by the act of transmitting a signal.
If I make a telephone call, and leave a voicemail message, the answering machine does not get up and walk around. Even a sufficiently advanced voicemail recorder would only be an interpretation of artifact left behind by a creature, and not the original being.
But if the substrate had artificial neurons, that could do everything normal neurons could, then it's plausible that consciousness could copy everything over. At that point, the only thing binding consciousness is the 'idea' that it belongs to the cells.
If you separated them before the host dies, then you'd have copied the consciousness into the substrate, and they would exist separately until you reattached it.
Wait until the host dies, then the consciousness would experience that death yet still persist. It would carry on experiencing through whatever senses the substrate offers.
Notice that it's not just a signal being transferred, it's the actual mechanics of consciousness, neurons firing and communicating. When the substrate, connected to the brain, communicates, it's just as if you added brain cells. So it's not just a signal, it's actual thought.
Well, at the very least, if it seems to be a diliberate signal originating from an organized intelligence AND anomalous, then it might be useful to consider the intersection of those two characteristics.
Where do we see intelligence and anomalies converge?
- War, and other forms of political conflict
- Accidents, even if non-destructive, like when the cat sits on the keyboard
- Experimentation, and research into novel discoveries, unfamiliar to a civilization
- Distress, final acts of desperation, where no hope is provided by circumstance, but behavior is engaged in anyway, because there is no consequence
Big ear sits upon the earth. It doesn't move, it just listens to whatever happens to be above it, and relies upon the rotation of the earth to simple multi-directionally. The Earth wobbles somewhat.
Let's assume that somebody else is broadcasting with a transmitter designed exactly like big ear, only in reverse (transmitting instead of receiving). Let's assume that they're very far away. Maybe their own planet wobbles.
What is the likelihood that we're even supposed to have heard the signal again? I mean, the way I'm imagining it is we have two drunk, blindfolded sailors, being randomly spun around as if before a pin-the-tail-on-the-donkey game, and each is holding a laser pointer, with no knowledge of each other. In the expanse of large open field, in the course of 1 year, how likely is it that the two laser beams will intersect? Ignoring the curvature of the earth, how much less likely is it the further apart they are? If they're, say, a light year apart (and have impractically powerful lasers), what is the likelihood then?
I have a different mental model of the nature of the signal. I don't imagine that it was transmitted as a focused beam attenuated by an aperture. My thinking is that it was a sphere shaped pulse generated by an apparatus like a broadcasting tower, or perhaps discharged from a device that targets a specific band of the EM spectrum.
When you think of it as an event similar to an electromagnetic pulse from a hydrogen bomb, and not as a beam from a laser pointer, it changes the rationale for why it might not be a repeatable event. If it was a pulse and not a beam, it might still be prone to occlusion, in terms of whether pulse were generated on the surface of a planet, and on the side that only happened to be facing toward us at the time (not away), while our antenna was pointed at the night sky, but that still increases the probability of reception.
The alternative concept for a pulse, is that it was generated from a small space craft or space probe, and not on a planet capable of eclipsing the signal.
Considering that it lasted 72 seconds, that might fit the profile of a weapon, if you consider the duration of typical video of a mushroom cloud. 72 seconds might also fit the profile of a jamming signal generated while a weapon was en route, to prevent detection while being delivered to a target.
72 seconds is the duration of time that any particular patch of sky is in range for Big Ear to listen to. To offer another imperfect analogy, imagine yourself on a train in a pitch black tunnel. There's a break in the tunnel that lasts for 72 seconds at your current speed. The light signals you noticed for those 72 seconds didn't necessarily last for only 72 seconds, they were simply not visible after you went back into the tunnel.
But with what motive? If you were to create a single high-energy pulse, deliberately, and willfully apply a degree of entropy to scramble the signal, why?
Randomness wouldn't have a motive. In fact, that's my suggestion.
You cited several scenarios wherein intelligence and anomalies converge, and I am suggesting that randomness is another possible (and perhaps likely) one.
I suppose this possibility is not unlike your accident suggestion but, perhaps, less bounded.