外星文明死了会留下什么？十种死亡签名（原声文稿）

Transcript of 外星文明死了会留下什么？十种死亡签名 （中文完整文稿）。

We tend to view the discovery of alien life positively in astronomy.

A distant signal might be picked up, or we might see a functioning Dyson swarm or other technosignature that tells us that there are active aliens out there in a positive way.

The solar system not so much, alien invasions and such.

But clearly that has not happened or we'd be a charcoal briquette by now.

But for distant astronomical phenomena and evidence of distant alien civilizations, we tend to think of it in the positive because, well, they are distant.

But lurking in the underbelly of astronomy are a series of indicators that we can in principle detect that paint a different, unsettling picture of civilizations going extinct, necros signatures, instead of technosignatures, or eventual danger to Earth. Earth.

So in celebration of spooky November, here are 10 very unsettling alien necrosignatures that we might pick up.

Intent, the title of my upcoming new book, is the necrosignature. Number 10.

The Methane Rise Extinction Indicator This particular one would be really disturbing to see.

It's definitely a necrosignature, not an active technosignature, but represents represents one that presents a very recent technosignature, but the civilization which created it is very likely extinct.

This is also a very short -lived technosignature, and if we ever see this, it represents a very terrifying possibility about the universe.

This starts with a simple but spooky biosignature, that interestingly is nominally within the detection capabilities of the James Webb Space Telescope under the right conditions.

It deals with seeing a methane spike in the atmosphere of an exoplanet, along with related chemicals that would indicate that this exoplanet is going through a very rapid extinction event.

Earth itself may have shown this short -lived signature after the impact that killed the dinosaurs because it would have generally devastated all life on Earth, even if it didn't cause the outright extinction of the affected species.

This methane rise would occur as decomposition bacteria analogues at that exoplanet would immediately gorge themselves on all the rotting vegetation and life there after a massive death event. Here's the problem.

If you also detect telltale artificial chemicals in the atmosphere of that world, such as CFCs, then you have very likely just watched a civilization hit its great filter, and very possibly its wholesale extinction.

And here's the scary part. This necrosignature is very short -lived.

You would see the spike and then the decline in decomposition gasses, but it would only last a few thousand years.

If you just happen to see this, essentially the first moment you could detect it, then statistically, this is very likely to be a common occurrence.

The great filter will have been found.

This collapses the Fermi Paradox down to one single reality.

All civilizations self -destruct one way or another.

We would then have to ask the question, when will it happen to us?

The Shkadov Escape Thruster This particular one is not a necrosignature per se, but is one of the more quirky of the possible technosignatures.

The idea is simple, it's a Shkadov thruster, where you build half a Dyson Sphere around a star and position it such that it directs the star's energy in one direction as a thruster.

This would be the main method of moving a star, and you can actually get that star moving very briskly over time to very high speeds, called proper motion in astronomy. There would actually be three potential signatures here.

One would be a star moving abnormally rapidly across space, and the second would be a telltale weird light curve for the star.

The third would be what direction the star is moving and what was its origin point.

This one is interesting.

It may not be seen even if you do see indicators of a thruster.

It could just be that this is how highly advanced aliens move stars around.

But if that origin point was near a star that potentially is about to go supernova, or the point is a supernova remnant, then you are seeing aliens that went through all that massive trouble to build a thruster in order to turn their own star system into an escape starship.

We could even calculate if they safely made it.

As they say in maritime time safety, the best lifeboat is the ship itself.

The Dyson Sphere Remnant This is another necrosignature, at least possibly, but not necessarily.

This idea stems from the usual Dyson Sphere concept, where you build a huge sphere around your star in order to collect all of its energy.

This would be very difficult, but it's actually been shown that a Dyson Sphere of this nature isn't entirely impossible, but it has a lot of rules on how it could operate.

More likely is a Dyson Swarm, which is how Dyson himself envisioned it.

The solid sphere should actually be called a Stapledon sphere, but the swarm is much more doable in that it's just a huge array of energy collecting satellites in orbit of a star.

We're already building that with our solar powered spacecraft, so it's doable.

But the problem is, if you detect a candidate Dyson Sphere that appears under construction, and those that have watched this channel and astrobiology in general long enough to remember, this was initially on the table for a Tabby Star, but whatever that is seems to be some kind of dust.

The problem is that it's very difficult unless you watch for a very long time to know if the sphere is under construction, being demolished, or falling apart because it was abandoned.

If we ever did unequivocally detect such a thing and confirming it would be relatively straightforward as anything technological related to a Dyson Sphere would block the starlight 100 % in a light curve, then you can't really tell which of the three options is going on without watching for thousands of years.

But a degrading abandoned sphere would presumably take longer than a demolition, indicating that the civilization is no longer maintaining it. it.

Why would probably remain unknown, but one option is that the builders had somehow gone extinct. Number 7.

The Revenge of George Lucas One of the most famous ideas from Star Wars is that of the Death Star, who could forget it, a giant, spherical, fully operational space station that can destroy entire planets. Interestingly, the Death Star is not a Dyson sphere. It wasn't big enough.

Or Obi -Wan Kenobi wouldn't have said that's no moon, that's a space station, suggesting it was much smaller than a planet.

Surprisingly though, the idea of a Death Star of this nature, though it need not be a sphere, actually is within the realm of plausibility.

Basically you simply build a space station with a laser large enough to strike another planet.

This would probably require the target planet to be nearby to the attacking planet.

But you could do this if you have two inhabited planets in the same star system and there is either a war going on or one of the planets wants to sterilize the surface of the other.

But you would think that there would be easier ways to do that.

But this would be detectable in principle as the leakage from the laser would be very powerful and would be detectable in the right SETI experiment. 6.

The Two Distant SOS SETI SIGNAL This particular signature would be a sad one to see.

It would represent, presumably, a necrosignature in progress.

It's the idea of a SETI signal that we might pick up that constitutes an SOS signal from an alien civilization if it could be decoded.

It might be sent because their world is dying, or they are too close to eminent supernova, or have gotten themselves in sufficient trouble to appeal to the rest of the galaxy to come and save them.

The problem is, if we picked up such a signal and could decode it, there is nothing currently we can do about it.

Or even if we could, we probably would not be able to cross the stars, and arrive in time with whatever method of evacuation we could come up with in the far future when we could cross the stars.

of course, we would simply have to watch in horror, along with very probably the rest of the galaxy, as the signal eventually goes dark. Number 5. The Disappearing Star System.

This is an interesting signature because it may or may not be a necrosignature, and it's something we've actually seen in astronomy potentially.

It represents a loose transient, where something is there, and then it no longer is, when you look again, an active area for the Vasco project astronomers.

The idea is this, you see a star system and then something about that star system rapidly changes, which could indicate that it's being consumed by large von Neumann probes.

How we've seen this isn't that many years ago, a protoplanetary disk was seen by the IRAS satellite in the 1980s around the star TYC 8241 -2652.

When astronomers looked again a mere two and a half years later, the disk was mostly gone.

There's really no satisfying explanation for this, it happened so fast, but the best explanation is the dust very rapidly fell into its star.

But that's very very rapidly for such a thing, and somewhat implausible stretching physics.

Another option is that the dust was consumed by von Neumann probes of large size, but that would require a lot of them.

And even then, that stretches the physics of how fast they could do it. So no one knows what happened at this star.

Now this particular star is young, so it's not likely that it had time to form any indigenous life, or potentially even planets.

But imagine if this were seen over time in a system that is old, and did have detectable planets, then they simply disappeared, one by one, very rapidly.

That would potentially be a necrosignature of a civilization getting eaten by probes, but it's not really likely we would ever know.

And of course there would always be the explanation that the worlds were destroyed, which would make a whole lot of detectable dust, fell into their star or were ejected.

But it would be interesting indeed, especially if it happened very fast as it did with that dust disc. Number 4 The Dyson Death Sphere Beam beam.

This one is a necrosignature but it is distinct from a death star in that it really isn't a technological death laser but much worse.

It would be a result of aiming and cutting a hole in a Dyson sphere in order to emit a beam of concentrated stellar energy out of the hole aimed at another world. This would utterly destroy a world.

It would be so powerful being that it is the power of a star being directed like that that it could destroy worlds at long distance across a galaxy.

Everyone in the galaxy would see this, you couldn't hide it.

And I suspect most of us in the galaxy would wonder exactly what was going on, who was being destroyed, and who built the death sphere.

Which in actual fact could be done with a lot of stabilization, as the beam would create a whole lot of thrust, and you wouldn't want it turned on for very long.

But involving one plausible type of Dyson Sphere. here.

It merely needs a hole. Thankfully, we have the capability to have easily seen this long before now. And we simply don't.

So while this would probably be a necker signature, it's one we can probably eliminate for the Milky Way. Number 3.

The Nearby Swarm Fage This one would be interesting.

Because in a way it's similar, but not exact by any means.

It's very different in reality relative to Andy Weir's concept in Project Hail Mary but nothing close enough to be a spoiler.

There are a few interviews I did with Andy Weir over to Vent Horizon, links below. As a note, no spoilers.

I merely recommend reading the book or seeing the movie as it's some of the best sci -fi in recent years.

Anyway, here the idea is that we see a cloud of something around a star, probably appearing as dust in the infrared, and it appears to be consuming a star system.

This might indicate an attack on that system, thus a necrosignature.

But it could also indicate a very extensive nanotechnological mining operation, or a large probe mining operation that is producing a lot of mind -tailings of material it's releasing its dust into space.

Interestingly, Tabi Star, as that story sits today, is on the table for this, as we still don't understand the dust signature at that star, it's still weird.

But it would be a long shot and hard to determine if that's what's happening.

I think the big question would be if aliens had somehow created a dangerous nanotechnology that got out of hand and ate them to produce more nanotechnology.

The Warning Star Signpost This one is spooky for a number of reasons, not the least of which is that we may have detected it. The idea is old.

Back in the 1960s, Sagan and Shlovsky noted that if you ever saw a plutonium in a star, star, you were seeing a techno -signature of an alien civilization, salting their star with elements that do not occur in sufficient quantities in nature to be there, or at all for everything above plutonium on the periodic table.

Plutonium does occur, but only in very tiny atom -by -atom quantities in highly radioactive geologic deposits.

They took it to be a steady signature if we ever saw it, aliens trying to tell the galaxy that they exist.

We have seen such a thing with a star known as Shibilsky Star or HD -101 -065, which in one study was found to have all sorts of upper elements, plutonium and above, on the table.

And there is no known mechanism in stellar physics to have caused this.

If the observation is correct, then either there is some titanic and Nobel Prize worthy mechanism in nuclear physics that we don't know about, or it's frankly aliens dumping nuclear waste in their star.

star. Though you'd think plutonium would be useful to keep around, certainly is for us.

But there is another interpretation, and only indirectly points to a technosignature.

Another reason aliens might salt their star with all these elements is as a warning.

A signpost indicating do not approach this system.

We have very advanced, very dangerous nuclear physics, and the technology to do much more, including alter our star. Stay away.

The immediate question is what exactly lurks out there that they feel the need to go through the extreme effort to try to warn away?

Did they detect necrosignatures caused by that something or someone?

Did they come into contact with it somehow to a bad outcome?

When will that something come for us?

The Blue Shifted SETI Signal This is simply related to Radio SETI and basically we have a 50 -50 chance of seeing this if we ever detect a SETI candidate.

It's blue shifting and red shifting in the spectrum of the radio emission.

Red shift means it's moving away from you, blue shift means it's moving towards you, but interestingly it might be difficult to determine that, because you can intentionally mask a signal and make it appear shifted either way.

You go to a signpost frequency in SETI, say the hydrogen line, and put a signal just above it.

Assuming that the original signal was exactly at the hydrogen line, one might assume blue shift, or below it red shift, but there would be no way to know for shifting.

So this would be difficult to determine if not impossible, but interestingly, the famous WAF signal was showing blue shift, or intentional transmission just above the hydrogen line.

You can't tell the difference, but if blue shifted, it indicated a very slow motion, like really slow, on level with our spacecraft, towards us and shifting in a signal can mean a rotating planet or an orbiting one but a strongly blue -shifted signal with increasing signal strength would be scary it would indicate that the source could be moving towards you very rapidly and if that never changes then it could indicate that something is coming which could also mean that we will become a necrosignature to anyone that knows we are here.

Thanks for listening I'm futurist and science fiction author John On Michael Goudier currently bringing up the Shkadov lifeboat, what if we see that in turn the radiotelescopes to it and the sending message we get is just the aliens going wee as they haul it across the Milky Way.

I dunno, that would be a fun way to detect aliens.

And be sure to check out my books at your favorite online book retailer and subscribe to my channel so regular, in -depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we liiiive.