Observational Signals of Self-Destructive Civilisations

[Tachyon]

http://arxiv.org/abs/1507.08530

[Drashner1]

Hm. Interesting. It's not wanting to download very fast for me right now, but I'll aim to sit down and give it a read thru later.

Considering this in an OA context - telescopes from the early part of the timeline on might have found examples of this. A civ that had killed itself could make an interesting (or poignant) EG article. Or, if we have such a world already, it could be mentioned that it was initially discovered using telescopic observation.

Todd

[Bear]

A civilization that killed itself thousands of years previously might be having the evidence of society preceding its demise (audio/video/etc signals) just now reaching some part of terragen civ, where it can be studied by people who have already seen (from sources closer to the event via wormhole travel) the evidence of that society during its demise (EMPs, metric weapon shockwaves, wormhole collapse energy bursts, neutrino bursts, premature novas, etc) and after (expanding debris clouds, elevated levels of dust-borne radiation, wandering autowars picking off escaping colony ships, populations selling themselves into slavery in exchange for basic lifesupport, etc, followed by decreasing signal sources and evidence of technological regression... ).

It would be interesting to compare the signals generated at different times during the process, and having seen a spectacular explosion at point A, you can retreat ten or fifty light years to point B and set up your array knowing exactly where to point it to pick up the events that led to the destruction.

In fact I can see the lightspeed wavefront of such an event traversing terragen civilization becoming an object of study in itself; radio-archaeologists would know about where it had propagated to and where the listening posts would be in the next couple of centuries, and might build entire careers studying it as it passes by, then relocating and studying it again. So there'd be an expanding wavefront of researchers playing leapfrog with the wavefront of evidence-of-destruction, for many many centuries.

[stevebowers]

The most significant signals emitted by a dying OA-scale civilisation would be visible from many gigalight years. Artificial supernovae as detonated by Verifex (and, I seem to remember, on other occasions by other parties) would be the brightest events, I think; they could probably be distinguished by their light-curves and spectroscopic characteristics - for a start, it would be practically impossible for a sun-like star to explode normally without some sort of artificial help.

Another event that would be detectable from a long way away, but not quite so bright, would be an attack by a Nicoll-Dyson laser; a planet or megastructure would suddenly flare up to sun-like brightness. Or a collision between two megastructures would release a lot of energy, as would the destruction of a dynamic megastructure such as a suprasphere and the release of its kinetic energy. The release of energy would be relatively slow, but could be long lasting and produce a lot of visible debris.

[iancampbell]

The most significant signals emitted by a dying OA-scale civilisation would be visible from many gigalight years. Artificial supernovae as detonated by Verifex (and, I seem to remember, on other occasions by other parties) would be the brightest events, I think; they could probably be distinguished by their light-curves and spectroscopic characteristics - for a start, it would be practically impossible for a sun-like star to explode normally without some sort of artificial help.

Another event that would be detectable from a long way away, but not quite so bright, would be an attack by a Nicoll-Dyson laser; a planet or megastructure would suddenly flare up to sun-like brightness. Or a collision between two megastructures would release a lot of energy, as would the destruction of a dynamic megastructure such as a suprasphere and the release of its kinetic energy. The release of energy would be relatively slow, but could be long lasting and produce a lot of visible debris.

This. Taking the idea a little further, I imagine that the detonations of metric weapons of one sort or another might have quite distinctive signatures.

[Matterplay1]

http://arxiv.org/abs/1507.08530

I note that grey goo (thought to be intentional and aggressive in these scenarios, rather like an all-out nuclear war, rather than purely accidental) is considered as a possibility. Our use of the word 'goo' is not as old-fashioned or as silly as some of us fear, I think, if it makes it into a paper like this one.