Author Topic: Could Fast Radio Bursts Be Powering Alien Probes?  (Read 6288 times)

Offline Star One

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Press release from Harvard so not something to be dismissed lightly.

Quote
Cambridge, MA -
The search for extraterrestrial intelligence has looked for many different signs of alien life, from radio broadcasts to laser flashes, without success. However, newly published research suggests that mysterious phenomena called fast radio bursts could be evidence of advanced alien technology. Specifically, these bursts might be leakage from planet-sized transmitters powering interstellar probes in distant galaxies.

"Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven't identified a possible natural source with any confidence," said theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. "An artificial origin is worth contemplating and checking."

As the name implies, fast radio bursts are millisecond-long flashes of radio emission. First discovered in 2007, fewer than two dozen have been detected by gigantic radio telescopes like the Parkes Observatory in Australia or the Arecibo Observatory in Puerto Rico. They are inferred to originate from distant galaxies, billions of light-years away.

Loeb and his co-author Manasvi Lingam (Harvard University) examined the feasibility of creating a radio transmitter strong enough for it to be detectable across such immense distances. They found that, if the transmitter were solar powered, the sunlight falling on an area of a planet twice the size of the Earth would be enough to generate the needed energy. Such a vast construction project is well beyond our technology, but within the realm of possibility according to the laws of physics.

Lingam and Loeb also considered whether such a transmitter would be viable from an engineering perspective, or whether the tremendous energies involved would melt any underlying structure. Again, they found that a water-cooled device twice the size of Earth could withstand the heat.

They then asked, why build such an instrument in the first place? They argue that the most plausible use of such power is driving interstellar light sails. The amount of power involved would be sufficient to push a payload of a million tons, or about 20 times the largest cruise ships on Earth.

"That's big enough to carry living passengers across interstellar or even intergalactic distances," added Lingam.

To power a light sail, the transmitter would need to focus a beam on it continuously. Observers on Earth would see a brief flash because the sail and its host planet, star and galaxy are all moving relative to us. As a result, the beam sweeps across the sky and only points in our direction for a moment. Repeated appearances of the beam, which were observed but cannot be explained by cataclysmic astrophysical events, might provide important clues about its artificial origin.

Loeb admits that this work is speculative. When asked whether he really believes that any fast radio bursts are due to aliens, he replied, "Science isn't a matter of belief, it's a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It's worth putting ideas out there and letting the data be the judge.”

The paper reporting this work has been accepted for publication in the Astrophysical Journal Letters and is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

https://www.cfa.harvard.edu/news/2017-09

Here's the pre-print paper which has been accepted for publication in Astrophysical Journal Letters.

https://arxiv.org/abs/1701.01109
« Last Edit: 03/09/2017 07:46 PM by Star One »

Offline Star One

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #1 on: 03/11/2017 08:12 AM »
I see this has now been widely reported often in a rather over excited way.

Offline gospacex

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #2 on: 03/13/2017 04:09 PM »
"""
NASA found that we are not alone in the Universe.
Is this a good or bad thing?
Let's ask the giant 200 km long alien cruiser currently in orbit of Saturn!
"""

Offline momerathe

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #3 on: 03/15/2017 02:38 PM »
I think this is one for Betteridge's law of headlines.
thermodynamics will get you in the end

Offline Star One

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #4 on: 03/15/2017 02:59 PM »
I think this is one for Betteridge's law of headlines.

However, at least one article found that the "law" does not apply in research literature. Which this originally is.

Offline Stormbringer

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #5 on: 03/21/2017 07:28 AM »
I hope not. I heard those alien probes hurt a lot as it is.


("Well it's what i heard!")

Provided aliens at an appropriate tech level exist (as we have speculated based on our own understanding of what is possible ) sooner or later we will detect their technological signatures.
« Last Edit: 03/21/2017 09:08 AM by Stormbringer »
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Offline IRobot

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #6 on: 03/21/2017 08:19 AM »
I think the most speculative side of this is to consider that beamed energy on a planetary scale is what more advanced civilizations would use.

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #7 on: 03/21/2017 12:51 PM »
The huge problem with any alien hypothesis is that it has to explain why they are such underachievers.

If these radiobursts were all aliens travelling from A to B, why haven't they converted the universe yet? Any sort of exponential growth would have radically changed the universe's appearance by now.

I don't think you can even argue that every single species is obsessed with conservation, because the universe as it is, is very wasteful, with suns pouring all but a billionth of their energy into the void.
« Last Edit: 03/21/2017 12:51 PM by KelvinZero »

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #8 on: 03/21/2017 06:16 PM »
Well, if stop ignoring the tendency of civilizations to stagnate after a few centuries, and even collapse with or without outside help, and usually only recover by being replaced by another civilization, combined with the fact that going to another star gives you no new kinds of materials, no new value, little new knowledge with practical applications, etc, it's easy to see there's no drive to completely fill up solar systems enough for us to detect the IR emissions.

Civilizations don't expand mathematically. They follow the most valuable sites: the best farmlands, the richest mines, rare crops, cheap labor, etc. Take those away, and growth eventually stagnates. Not enough people would go to the nearest solar system or even the nearest planet just to have more of the same. Instead, they would continue to steadily expand the population in their own solar system/planet, with an increasing percentage of the population having less and less to do that the people that do have a job are willing to pay for. So either the population growth eventually stagnates, which I don't think is likely in the long term, or the increasing cost of sustaining an increasingly indifferent population eventually causes the civilization to collapse in on itself. And that's long before reaching a population large enough to fill Dyson spheres. Without a neighboring civilization to replace it, this cycle just keeps repeating. While the people that do settle other stars/planets, go to settle other stars long before their population reaches a density that our instruments can detect.

I know this is not a popular idea, because this is exactly the problem that Mars faces: until there is something there that people of Earth are willing to pay for, it will never attract a big enough population to act as a 'backup' of earth.

Offline Cinder

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #9 on: 03/22/2017 06:47 AM »
The huge problem with any alien hypothesis is that it has to explain why they are such underachievers.

If these radiobursts were all aliens travelling from A to B, why haven't they converted the universe yet? Any sort of exponential growth would have radically changed the universe's appearance by now.

I don't think you can even argue that every single species is obsessed with conservation, because the universe as it is, is very wasteful, with suns pouring all but a billionth of their energy into the void.
The universe doesn't get converted instantly.  There is some lapse of time where it is being converted, including a part of that lapse where the conversion is merely beginning; and then there's our local bias.  The bias of only seeing so little and extrapolating from it.  We could be seeing much less than what is out there.  The radio burst method (assuming it is artificial) may be just the tip of the iceberg, the unseen depths of the iceberg being our finite perception bias.

I would still take that same perception bias as pointing to some unknown non-living explanation.  It's just too much like the universe as we've known it to time and again dwarf our imagination (viz. flat earth and geocentrism and heaven's roof, and galaxies shining thru intergalactic voids perceived as mere stars etc), and we have such a dearth of data on these signals compared to the things in our more immediate neighbourhoods; those things that are just passing over the threshold of "certainty".
« Last Edit: 03/22/2017 06:48 AM by Cinder »
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Offline ChrisWilson68

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #10 on: 03/22/2017 07:25 AM »
Well, if stop ignoring the tendency of civilizations to stagnate after a few centuries, and even collapse with or without outside help, and usually only recover by being replaced by another civilization, combined with the fact that going to another star gives you no new kinds of materials, no new value, little new knowledge with practical applications, etc, it's easy to see there's no drive to completely fill up solar systems enough for us to detect the IR emissions.

Civilizations don't expand mathematically. They follow the most valuable sites: the best farmlands, the richest mines, rare crops, cheap labor, etc. Take those away, and growth eventually stagnates. Not enough people would go to the nearest solar system or even the nearest planet just to have more of the same. Instead, they would continue to steadily expand the population in their own solar system/planet, with an increasing percentage of the population having less and less to do that the people that do have a job are willing to pay for. So either the population growth eventually stagnates, which I don't think is likely in the long term, or the increasing cost of sustaining an increasingly indifferent population eventually causes the civilization to collapse in on itself. And that's long before reaching a population large enough to fill Dyson spheres. Without a neighboring civilization to replace it, this cycle just keeps repeating. While the people that do settle other stars/planets, go to settle other stars long before their population reaches a density that our instruments can detect.

I know this is not a popular idea, because this is exactly the problem that Mars faces: until there is something there that people of Earth are willing to pay for, it will never attract a big enough population to act as a 'backup' of earth.

You're taking the wrong lessons from history.  Human societies always expand to the limits of the carrying capacity of whatever places they inhabit, and they always expand into all available habitats.

Sure, there are "collapses" in the sense of breakup of larger political entities into smaller ones and replacement of some political entities with others.  That sometimes leads to a reduction in population and/or a reduction in the carrying capacity of an area.  But the population never stays much below the carrying capacity for long.

Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent.  A civilization can't help but grow until it reaches the carrying capacity of whatever environment it can expand into, unless a single central entity enforces some sort of rule to keep it from doing so.

We tend to forget that because it's been obscured by dramatic short-term changes in Western society in recent centuries, but that doesn't make it untrue.

Offline notsorandom

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #11 on: 03/22/2017 01:08 PM »
The lack of any relatively local aliens scooting around in their light sail starships isn't fatal to the hypothesis. The FRBs have been only observed in galaxies billions of light years away. The method of travel isn't faster than light. So the aliens would show up some time after their beams could be detected equivalent to how much slower their ships are. Likewise if we assume an alien civilization spreading out in all directions then they would do so only as fast as their ships could take them and their efforts to do so would be detectable long before their ships spread out. That also assume that they don't spend any time stopping to colonize or get some fresh air which would add even more time between the first detections and their arrival.

Assuming they could get up to 50% of c and they were 1 billion light years from Earth their first ships wouldn't start showing up any sooner than a billion years after they were first detected. If we are waiting for some company to drop by it gets even worse if we use some more conservative figures. FRB 121102 is thought to have happened 3 billion LY away and if their travel speed is only 20% (Breakthrough Starshot's speed) of c then it would take 15 billion years for them to get here and they would have been detectable for 12 billion years.
« Last Edit: 03/22/2017 02:04 PM by notsorandom »

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #12 on: 03/22/2017 07:20 PM »
Well, if stop ignoring the tendency of civilizations to stagnate after a few centuries, and even collapse with or without outside help, and usually only recover by being replaced by another civilization, combined with the fact that going to another star gives you no new kinds of materials, no new value, little new knowledge with practical applications, etc, it's easy to see there's no drive to completely fill up solar systems enough for us to detect the IR emissions.

Civilizations don't expand mathematically. They follow the most valuable sites: the best farmlands, the richest mines, rare crops, cheap labor, etc. Take those away, and growth eventually stagnates. Not enough people would go to the nearest solar system or even the nearest planet just to have more of the same. Instead, they would continue to steadily expand the population in their own solar system/planet, with an increasing percentage of the population having less and less to do that the people that do have a job are willing to pay for. So either the population growth eventually stagnates, which I don't think is likely in the long term, or the increasing cost of sustaining an increasingly indifferent population eventually causes the civilization to collapse in on itself. And that's long before reaching a population large enough to fill Dyson spheres. Without a neighboring civilization to replace it, this cycle just keeps repeating. While the people that do settle other stars/planets, go to settle other stars long before their population reaches a density that our instruments can detect.

I know this is not a popular idea, because this is exactly the problem that Mars faces: until there is something there that people of Earth are willing to pay for, it will never attract a big enough population to act as a 'backup' of earth.

You're taking the wrong lessons from history.  Human societies always expand to the limits of the carrying capacity of whatever places they inhabit, and they always expand into all available habitats.

Sure, there are "collapses" in the sense of breakup of larger political entities into smaller ones and replacement of some political entities with others.  That sometimes leads to a reduction in population and/or a reduction in the carrying capacity of an area.  But the population never stays much below the carrying capacity for long.

Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent.  A civilization can't help but grow until it reaches the carrying capacity of whatever environment it can expand into, unless a single central entity enforces some sort of rule to keep it from doing so.

We tend to forget that because it's been obscured by dramatic short-term changes in Western society in recent centuries, but that doesn't make it untrue.

So there are no ghost towns in the US? No deserted gold rush villages? No villages around route 66 that now have a fraction of their previous population because of highways? As far as I know, changes in the local carrying capacity is not why these towns failed.

People have been concentrating in cities for (tens of?) thousands of years, in far greater numbers than the carrying capacity of the local area, importing food from other regions, sometimes even separated by a sea. The size of the city only limited by the value it could create, to import whatever the inhabitants wanted to pay for. And eventually declining as whatever valuable goods or services the city produces, is exhausted or no longer unique or valuable. Food production is for farming villages. And the population of those farming villages has been impacted more by how much food can be produced per hour of labor (more food per man-hour meaning less people per km²), rather than how many people can be fed with the local produce.

Employment problems like the rust belt and coal country have been encountered through all ages. That is what ultimately drives population sizes. Not food, unless finding food is a full time job for most of the population.
« Last Edit: 03/22/2017 07:35 PM by high road »

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #13 on: 03/24/2017 06:24 AM »
The universe doesn't get converted instantly.  There is some lapse of time where it is being converted,
I won't continue this here because I would be pulling the thread too far off topic.

This is a more general problem that has been explored in detail. Lots of people have done the math and come to the same conclusion. It is pretty much the Fermi paradox which to me is an argument that interstellar civilisations must be exceedingly rare, very possibly none at all within the observable universe. If they exist they are strangely underachieving and it speaks very poorly for the odds of us ever amounting to anything, so personally I optimistically hope to never see signs of them. We will have to go out there and make our own aliens.

Offline spacenut

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #14 on: 03/24/2017 12:58 PM »
Look at Japan.  They import 50% of their food, import iron ore, coal, and limestone to make steel.  Basically they import almost all their raw materials and are heavy into manufacturing.  They once tried to take the raw materials by military expansion leading to WWII.  Now they trade for their raw materials and have become richer than they were before WWII. 

I have a book around here somewhere that says with nuclear power, the United States could sustain a population the size of China with our current standard of living.  Lots of big cities, unlimited power, vegetables grown in greenhouses instead of farmland.  Farmlands used for grain and cattle ranching.  Much like some of the Martian agriculture envisioning.

Anyway, this is off topic of alien probes.  If there are aliens, they may be expanding outside their solar system.  We are only just beginning.  What we learn from Martian agriculture, can be applied to earth to increase production. 

Offline Oli

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #15 on: 03/25/2017 01:21 AM »
Why would Aliens use radio waves though? I thought light sail concepts use lasers...

Edit: They mention potential reasons in the footnote on page 2 of the paper.
« Last Edit: 03/25/2017 01:44 AM by Oli »

Offline Orbiter

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #16 on: 03/25/2017 01:39 AM »
Why would alien civilizations in different galaxies use the exact same technique for interstellar travel is my question.
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Offline Phil Stooke

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #17 on: 03/25/2017 01:50 AM »
"I have a book around here somewhere that says with nuclear power, the United States could sustain a population the size of China with our current standard of living. "

That's what these poor aliens are trying to escape.

Offline Bob Shaw

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #18 on: 03/25/2017 02:58 AM »
FRBs are perhaps simply the anomalies du'jour, oddities seeking a semi-feasible explanation as regards ETI. Somehow, I doubt that we're seeing anything other than a natural event here.

There are, however, things which *might* be out there which *would* be rather more persuasive. These range from pan-galactic megastructures through to inappropriate IR individual signatures across otherwise normal galaxies and unusal metalicities/rotation/elements in otherwise standard stars. Sadly, there's no evidence of anything across the depths of time and space. We can calculate the rate at which self-replicating machine cultures might spread across individual galaxies at sub-light speeds (never mind more fragile organic cultures) and even locally we see no evidence of stellar industry.

There appear to be many opportunities for life to exist even in our own Solar System, but such life is likely to be highly adapted slime in most cases, and I fear that our own species may well be just about all there is in terms of intelligent life within the readily observable part of the universe. This is sad, but demonstrates that we need to nurture our own species and our planet - there are no lifeboats, nor is there anyone out there to save us from our mistakes. We have to grow up as a species!
« Last Edit: 03/25/2017 02:59 AM by Bob Shaw »

Offline Mark K

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #19 on: 03/25/2017 03:22 AM »
The universe doesn't get converted instantly.  There is some lapse of time where it is being converted,
I won't continue this here because I would be pulling the thread too far off topic.

This is a more general problem that has been explored in detail. Lots of people have done the math and come to the same conclusion.

Yeah ... oh wait the studies I have seen all project no visible civilizations at very reasonable probabilities. It is a universe where life would not be real detectable. Look at old  BIS journals from decades ago. Plus some G. Landis papers - with very reasonable assumptions, The models predict nobody over running anything. Space is big and time is long and travel energy costs are high. I haven't  actually seen an in depth study that came to another conclusion. Just some simple projections like Fermi's and a few others the other way.
 

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #20 on: 03/25/2017 11:00 PM »
... oh wait the studies I have seen all project no visible civilizations at very reasonable probabilities. It is a universe where life would not be real detectable. Look at old  BIS journals from decades ago. Plus some G. Landis papers - with very reasonable assumptions, The models predict nobody over running anything. Space is big and time is long and travel energy costs are high. I haven't  actually seen an in depth study that came to another conclusion. Just some simple projections like Fermi's and a few others the other way.
As I said, off topic here.

Im really busy at the moment but if you start another thread Im sure people can flood you with references.

I find it discouraging if you claim to have simply never encountered them though. That does not bode well for a future debate. Disagree, yes. But not encountered?

This is not a paper, but I remember the book https://en.wikipedia.org/wiki/The_Eerie_Silence as being something that struck the nail repeatedly on the head for me.

In any case, if we were seeing the flashes of interstellar travel from multiple different directions, that totally changes the parameters. Most of those arguments that attempt to explain underachievement that might allow other races to exist without detection are ruled out by multiple races all over the place succeeding in dabbling in interstellar flight.
« Last Edit: 03/25/2017 11:09 PM by KelvinZero »

Offline Star One

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Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #21 on: 04/03/2017 09:12 PM »
The first interferometric detections of Fast Radio Bursts

(Submitted on 29 Mar 2017)

Quote
We present the first interferometric detections of Fast Radio Bursts (FRBs), an enigmatic new class of astrophysical transient. In a 180-day survey of the Southern sky we discovered 3 FRBs at 843 MHz with the UTMOST array, as part of commissioning science during a major ongoing upgrade. The wide field of view of UTMOST (≈9 deg2) is well suited to FRB searches. The primary beam is covered by 352 partially overlapping fan-beams, each of which is searched for FRBs in real time with pulse widths in the range 0.655 to 42 ms, and dispersion measures ≤2000 pc cm−3. Detections of FRBs with the UTMOST array places a lower limit on their distances of ≈104 km (limit of the telescope near-field) supporting the case for an astronomical origin. Repeating FRBs at UTMOST or an FRB detected simultaneously with the Parkes radio telescope and UTMOST, would allow a few arcsec localisation, thereby providing an excellent means of identifying FRB host galaxies, if present. Up to 100 hours of follow-up for each FRB has been carried out with the UTMOST, with no repeating bursts seen. From the detected position, we present 3σ error ellipses of 15 arcsec x 8.4 deg on the sky for the point of origin for the FRBs. We estimate an all-sky FRB rate at 843 MHz above a fluence Flim of 11 Jy ms of ∼78 events sky−1 d−1 at the 95 percent confidence level. The measured rate of FRBs at 843 MHz is of order two times higher than we had expected, scaling from the FRB rate at the Parkes radio telescope, assuming that FRBs have a flat spectral index and a uniform distribution in Euclidean space. We examine how this can be explained by FRBs having a steeper spectral index and/or a flatter logN-logF distribution than expected for a Euclidean Universe.

https://arxiv.org/abs/1703.10173
« Last Edit: 04/03/2017 09:14 PM by Star One »

Offline Star One

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #22 on: 04/04/2017 03:47 PM »
More to the above.

New Options for Locating Fast Radio Bursts

http://www.centauri-dreams.org/?p=37448

Offline Vultur

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #23 on: 04/09/2017 05:25 AM »
Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent. 

I dunno. That would assume that the cultural traits that lead to reproducing more are "reliably" transmitted between generations, so that a culture that reproduces more becomes dominant. There are many reasons that might not hold true.

Higher reproduction might also be tied to higher instability in other ways, thus greater tendency towards collapse or destructive war... or just unwillingness to undertake interstellar colonization.

If FTL is impossible and Bussard ramjets etc. don't prove practical for anyone, then interstellar stuff will require very long timescales. Interstellar colonization then can't be driven by population pressures... it's just too slow.

Perhaps the only civilizations which do anything interstellar are those composed of extremely long-term thinkers, possibly extremely-long-lifespan entities.

--

And the universe as a whole shouldn't be "terraformed" or whatever by now.

If (as I rather expect) high-relativistic speeds are impractical for anyone, intergalactic travel should be insanely difficult even for the most advanced civilizations (making a vehicle, even a worldship, last the 29 million years it would take to get from here to Andromeda at 10% lightspeed, without any significant time-dilation benefit?)

Offline MP99

Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #24 on: 04/09/2017 07:55 PM »
The huge problem with any alien hypothesis is that it has to explain why they are such underachievers.

If these radiobursts were all aliens travelling from A to B, why haven't they converted the universe yet? Any sort of exponential growth would have radically changed the universe's appearance by now.

We don't have an explanation for dark energy. Possibly this is some side effect or intentional effect of advanced civilisations?

I wonder whether Mach Effect thrusters might have this as a side effect?

Cheers, Martin

Offline MP99

Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #25 on: 04/09/2017 08:32 PM »
Assuming they could get up to 50% of c and they were 1 billion light years from Earth their first ships wouldn't start showing up any sooner than a billion years after they were first detected.

Note that the paper discusses that the beams sweep across us, not that they are necessarily aimed at us. Of course, there could be further launches aimed at us which we wouldn't necessarily see.

Although I take the point that watching over a long enough period may eventually reveal beams from closer sources.

Cheers, Martin
« Last Edit: 04/09/2017 08:33 PM by MP99 »

Offline ChrisWilson68

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #26 on: 04/13/2017 10:30 PM »
The universe doesn't get converted instantly.  There is some lapse of time where it is being converted,
I won't continue this here because I would be pulling the thread too far off topic.

This is a more general problem that has been explored in detail. Lots of people have done the math and come to the same conclusion.

You've got to be kidding.  There's no consensus on this at all.  There's vigorous debate about this among scientists.  The math is only as good as the assumptions you put into your calculations.

Offline ChrisWilson68

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #27 on: 04/13/2017 10:34 PM »
Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent. 

I dunno. That would assume that the cultural traits that lead to reproducing more are "reliably" transmitted between generations, so that a culture that reproduces more becomes dominant.

It's not really reproduction if the offspring don't share traits like that.  For your theory to hold, there would have to never be true reproduction.  For my point to hold, there would only rarely have to be civilizations that actually reproduce and they would quickly dominate.

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #28 on: 04/14/2017 03:15 AM »
The universe doesn't get converted instantly.  There is some lapse of time where it is being converted,
I won't continue this here because I would be pulling the thread too far off topic.

This is a more general problem that has been explored in detail. Lots of people have done the math and come to the same conclusion.

You've got to be kidding.  There's no consensus on this at all.  There's vigorous debate about this among scientists.  The math is only as good as the assumptions you put into your calculations.
I can't respond to this because I don't really know what you are referring to. Im not even sure if I would agree with your interpretation of what I said. For all I know you are just reversing Cinder's statement.

I think the Paul Davies book "The eerie silence" pretty much covered positions that seem obvious to me. (been a while since I read it though) I think he is Chair of SETI so I don't think I am taking an extreme position against the possibility of aliens.

Im not saying there _cannot_ be reasons that prevent our spreading, just that if the "Great filter" is applied after this point in history then there is something strange, unexplained and dismal ahead of us. This is made even harder to explain if countless races all around us are achieving interstellar flight, and we are seeing their flashes all around us, but then we see nothing else... this is the only part that actually makes this conversation relevant to this thread.

Offline Vultur

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #29 on: 04/14/2017 05:27 AM »
Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent. 

I dunno. That would assume that the cultural traits that lead to reproducing more are "reliably" transmitted between generations, so that a culture that reproduces more becomes dominant.

It's not really reproduction if the offspring don't share traits like that.  For your theory to hold, there would have to never be true reproduction.  For my point to hold, there would only rarely have to be civilizations that actually reproduce and they would quickly dominate.

Not necessarily, if reproduction rate is not driven by genetic/biological traits. It already isn't on Earth - it's primarily driven by economic & social factors.


Im not saying there _cannot_ be reasons that prevent our spreading, just that if the "Great filter" is applied after this point in history then there is something strange, unexplained and dismal ahead of us.

Assuming there is anything like a 'Great Filter'. There needn't be, if extremely old/advanced civilizations tend not to be recognizable by us (either because they tend to be very stable, non-spreading & relatively low energy*, or because we have already observed their work but mistake it for natural phenomena).

*Advanced knowledge doesn't in itself imply high energy/resource use.

If there is a 'Great Filter', though, it seems likelier to be behind us than ahead. The technology you need to blow up civilization is the same technology that you need to get into space - it's inconceivable to me that there would be tons of civilizations but they all destroy themselves without exception in the 100 year window or so when they have the capacity for globally destructive war but before they have significant space colonies. (And if you built 'Project Orion' ships, that window could be something like 20 years.)

Especially since a civilization-destroying war wouldn't necessarily destroy the species, and even a thousand years or so to struggle back from a Dark Age is an eye-blink on an astronomical scale.

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #30 on: 04/14/2017 11:18 AM »
Is it worth starting a thread just on the Fermi paradox?

I find this guy quite entertaining, and he has a section on the Fermi paradox and various proposed solutions.
https://www.youtube.com/playlist?list=PLIIOUpOge0LulClL2dHXh8TTOnCgRkLdU

Offline RonM

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #31 on: 04/14/2017 02:37 PM »
Is it worth starting a thread just on the Fermi paradox?

It's been discussed many times in many threads. The actual "Fermi's Paradox" thread was moved to moderation, never to be seen again. Might work if people remember to respect other points of view, but for some reason people get really worked up over this purely theoretical discussion.

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #32 on: 04/14/2017 03:16 PM »
Any collection of beings would inevitably have to follow the same pattern unless somehow constrained by a single central entity.  That's just because whichever individuals reproduce more will become more prevalent. 

I dunno. That would assume that the cultural traits that lead to reproducing more are "reliably" transmitted between generations, so that a culture that reproduces more becomes dominant.

It's not really reproduction if the offspring don't share traits like that.  For your theory to hold, there would have to never be true reproduction.  For my point to hold, there would only rarely have to be civilizations that actually reproduce and they would quickly dominate.

They would dominate, reproduce ever faster until the growth in production of rare desirable goods can no longer keep up with their population growth and they are diminished by the resulting wars every time. If interstellar travel is hard, a quickly reproducing species cannot cross to another star. The only ones that can, are the ones that limit their population growth. As a result they don't achieve the population densities our telescopes would pick up, even if they do colonize many stars.

 
Call it a filter if you want. I rather see it as an example that the exponential growth model is a simplification that doesn't live up to reality.

Offline wes_wilson

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #33 on: 04/17/2017 11:34 PM »
The huge problem with any alien hypothesis is that it has to explain why they are such underachievers.

If these radiobursts were all aliens travelling from A to B, why haven't they converted the universe yet? Any sort of exponential growth would have radically changed the universe's appearance by now.

I don't think you can even argue that every single species is obsessed with conservation, because the universe as it is, is very wasteful, with suns pouring all but a billionth of their energy into the void.

About 70% of the universe is "dark matter"...  Maybe the universe's appearance has been changed radically and we're just still looking for a non-intellect driven process to explain it.
@SpaceX "When can I buy my ticket to Mars?"

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #34 on: 04/18/2017 04:27 AM »
About 70% of the universe is "dark matter"...  Maybe the universe's appearance has been changed radically and we're just still looking for a non-intellect driven process to explain it.
I have speculated about dark matter myself, wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres. Could be as dense as neutron stars, could be some material beyond our comprehension at the moment. Maybe we are living in the scraps. What if suns could hold civilisations of thinking plasma vortices or something, and all the planets were just like dandruff to them? Just of no interest?

These sorts of ideas have also been considered by other people and you can probably find mention of them and some discussion of the common objections in that Isaac Arthur link I posted just a bit earlier.

Offline stefan r

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #35 on: 04/18/2017 05:13 PM »
The lack of any relatively local aliens scooting around in their light sail starships isn't fatal to the hypothesis. The FRBs have been only observed in galaxies billions of light years away. The method of travel isn't faster than light. So the aliens would show up some time after their beams could be detected equivalent to how much slower their ships are. Likewise if we assume an alien civilization spreading out in all directions then they would do so only as fast as their ships could take them and their efforts to do so would be detectable long before their ships spread out. That also assume that they don't spend any time stopping to colonize or get some fresh air which would add even more time between the first detections and their arrival.

Assuming they could get up to 50% of c and they were 1 billion light years from Earth their first ships wouldn't start showing up any sooner than a billion years after they were first detected. If we are waiting for some company to drop by it gets even worse if we use some more conservative figures. FRB 121102 is thought to have happened 3 billion LY away and if their travel speed is only 20% (Breakthrough Starshot's speed) of c then it would take 15 billion years for them to get here and they would have been detectable for 12 billion years.
Not quite.  The standard model has the universe expanding.  v = H0D  So at 1 Gpc distance:
 v = 68,000 km/s. 
Launching at 20% c gives 59,600 km/s
So they would still drifting away from us if H0 is correct.

Offline punder

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #36 on: 04/18/2017 05:31 PM »
About 70% of the universe is "dark matter"...  Maybe the universe's appearance has been changed radically and we're just still looking for a non-intellect driven process to explain it.
I have speculated about dark matter myself, wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres. Could be as dense as neutron stars, could be some material beyond our comprehension at the moment. Maybe we are living in the scraps. What if suns could hold civilisations of thinking plasma vortices or something, and all the planets were just like dandruff to them? Just of no interest?

These sorts of ideas have also been considered by other people and you can probably find mention of them and some discussion of the common objections in that Isaac Arthur link I posted just a bit earlier.

It could be a testable hypothesis... if the percentage of dark matter vs. "normal" is found to be increasing over time, a possible reason (of course the last resort, after all natural explanations are exhausted) is that We and Everything Else Are Being Assimilated.   :o

Offline stefan r

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #37 on: 04/19/2017 02:08 AM »
... wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres....

Both the Dyson sphere and matrioshka brain radiate with the same luminosity as the star they draw energy from.  The luminosity is low temperature emission. 

Maybe something like this:  ll pegasi

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #38 on: 04/19/2017 06:12 PM »
... wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres....

Both the Dyson sphere and matrioshka brain radiate with the same luminosity as the star they draw energy from.  The luminosity is low temperature emission. 

Maybe something like this:  ll pegasi

Sure, the luminosity is the same, but considering the re-emitted flux is much lower due to the bigger surface area, wouldn't a star with a partial Dyson Swarm/Matrioshka Brain/... appear to us as a smaller and/or colder star that is somehow much heavier than it seems to be based on its apparent luminosity? Isn't the star's brightness our main indicator of its size? So how would we know our formula to calculate their size is influenced by such phenomena unless we see large differences between the sizes we think they are and the gravity they appear to have? (which happens to be the case)

Offline stefan r

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #39 on: 04/20/2017 03:09 AM »
... wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres....

Both the Dyson sphere and matrioshka brain radiate with the same luminosity as the star they draw energy from.  The luminosity is low temperature emission. 

Maybe something like this:  ll pegasi

Sure, the luminosity is the same, but considering the re-emitted flux is much lower due to the bigger surface area, wouldn't a star with a partial Dyson Swarm/Matrioshka Brain/... appear to us as a smaller and/or colder star that is somehow much heavier than it seems to be based on its apparent luminosity? Isn't the star's brightness our main indicator of its size? So how would we know our formula to calculate their size is influenced by such phenomena unless we see large differences between the sizes we think they are and the gravity they appear to have? (which happens to be the case)

A good example is four 15 watt florescent bulbs, a 60 watt incandescent bulb, and an electric heater using 60 watts.  Normal human reaction is to say that the florescent bulbs are much "brighter" and that the electric heater is not a light.  The bolometric luminosity is the same for each item (assuming we ignore convection or add watts to compensate).  The visual luminosity of the florescent is much higher.  In parts of the infrared the incandescent has highest luminosity.  In microwave frequency the heater is much "brighter". 

I was assuming total sphere.  If you had a 20% continuous coverage the spectrum would look odd.  At high frequencies you would have black body radiation 20% smaller than expected for a similar size star then a step up to a spectrum for a cooler black body with a much larger surface area.

My instinct is that variable coverage is more likely in a partial sphere.  As coverage varies from 1% to 20% the visual part of the star's spectrum would vary between 80 and 99% visual luminosity.  The far infra-red spectrum would also vary but not necessarily synchronized with the visual variability.  The radiators could be on multiple surfaces.  Is possible that most would radiate heat away from the star so far infra-red would vary inverse to visual. 

A partial dyson sphere acting as a Shkadov thruster would have less infra red (compared to stationary) if it was moving towards us or perpendicular.  If they are moving away from us the infra red luminosity would be much higher.  Mirrors could create strange stars with higher visual luminosity too but doubling is unlikely. 

Orbiting mirrors and radiators also red and blue shift as they move. 

All stars are a point of light in our telescopes. 

Offline KelvinZero

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #40 on: 04/20/2017 06:40 AM »
Both the Dyson sphere and matrioshka brain radiate with the same luminosity as the star they draw energy from.  The luminosity is low temperature emission. 
Yep.. that was sort of my point. There are plenty of good ideas but then we must go and look for the objections. It is likely the idea has been kicked back and forth a few times and people have found ways to explore it using basic principles.

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #41 on: 04/20/2017 07:09 AM »
... wondered if most of the universe is hidden away in dark "matrioshka brain" like objects. Could be Dyson spheres....

Both the Dyson sphere and matrioshka brain radiate with the same luminosity as the star they draw energy from.  The luminosity is low temperature emission. 

Maybe something like this:  ll pegasi

Sure, the luminosity is the same, but considering the re-emitted flux is much lower due to the bigger surface area, wouldn't a star with a partial Dyson Swarm/Matrioshka Brain/... appear to us as a smaller and/or colder star that is somehow much heavier than it seems to be based on its apparent luminosity? Isn't the star's brightness our main indicator of its size? So how would we know our formula to calculate their size is influenced by such phenomena unless we see large differences between the sizes we think they are and the gravity they appear to have? (which happens to be the case)

A good example is four 15 watt florescent bulbs, a 60 watt incandescent bulb, and an electric heater using 60 watts.  Normal human reaction is to say that the florescent bulbs are much "brighter" and that the electric heater is not a light.  The bolometric luminosity is the same for each item (assuming we ignore convection or add watts to compensate).  The visual luminosity of the florescent is much higher.  In parts of the infrared the incandescent has highest luminosity.  In microwave frequency the heater is much "brighter".
 

So how would we know wether we're looking at a red (super)giant or a main sequence star of the same luminosity surrounded by a radiator Dyson swarm approaching the density of a full Dyson sphere?

Quote
My instinct is that variable coverage is more likely in a partial sphere.  As coverage varies from 1% to 20% the visual part of the star's spectrum would vary between 80 and 99% visual luminosity.  The far infra-red spectrum would also vary but not necessarily synchronized with the visual variability.  The radiators could be on multiple surfaces.  Is possible that most would radiate heat away from the star so far infra-red would vary inverse to visual. 

A partial dyson sphere acting as a Shkadov thruster would have less infra red (compared to stationary) if it was moving towards us or perpendicular.  If they are moving away from us the infra red luminosity would be much higher.  Mirrors could create strange stars with higher visual luminosity too but doubling is unlikely. 

Orbiting mirrors and radiators also red and blue shift as they move. 

All stars are a point of light in our telescopes.

As far as measuring diameters is concerned, all stars are badly resolved blobs of light surrounded by diffraction patterns in our telescopes.

Incomplete Dyson swarms with individual elements between the size of NYC and Luna, assuming there's an upper limit to their practical size, would not be detectable by our current or upcoming telescopes. We would assume the star is just somewhat more variable. The movement and reflected radiation of the individual elements is not enough to be detectable as an individual space station/planetary body. The scattering effect they have on the radiation emitted by the star might be actively filtered away to resolve the star better.

And all this still assumes that ETI somehow doesn't come to the conclusion that at a certain scale, rather than using the radiation emitted by natural fusion reactors, it's far more practical to just do the fusion in not-so-natural fusion reactors and become independent of stars in the first place.

With 84% of all matter unaccounted for by our measurement of star sizes, and our telescopes having a limited capability to pick up such artificial fusion reactors emitting about as much energy as a brown dwarf, there's plenty of room to hide in plain sight.

Offline as58

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #42 on: 04/20/2017 06:57 PM »

So how would we know wether we're looking at a red (super)giant or a main sequence star of the same luminosity surrounded by a radiator Dyson swarm approaching the density of a full Dyson sphere?

Their spectra would be completely different.

Offline stefan r

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #43 on: 04/21/2017 12:29 AM »

So how would we know wether we're looking at a red (super)giant or a main sequence star of the same luminosity surrounded by a radiator Dyson swarm approaching the density of a full Dyson sphere?

Their spectra would be completely different.

A red giant should have a mostly hydrogen spectra.  The Dyson sphere would have characteristic spectrum from whatever material was radiating.  For example, an aquarium would have water emissions and glass emissions.  The glass also blocks some frequencies.  If the Aliens use cast iron radiators then we would detect lots of iron.  If they paint the radiators with exterior house paint there will be TiO2 emission.   

Astronomers determine rotational velocity by looking at the red and blue shifts.  A typical Dyson swarm is likely to be rotating at orbital velocity.  That would not be a stable situation for a gas.  The Dyson swarm can orbit in perpendicular directions.  Stars rotate on one axis. 

I am not sure if graphene and carbon nanotubes would be identified as carbon dust (soot).  If I was publishing the data I would just state the molecular structures and not mention the construction possibilities.

For many stars that are inside of dust clouds we cannot determine whether it is a Dyson sphere.

Offline as58

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #44 on: 04/21/2017 06:38 AM »

So how would we know wether we're looking at a red (super)giant or a main sequence star of the same luminosity surrounded by a radiator Dyson swarm approaching the density of a full Dyson sphere?

Their spectra would be completely different.

A red giant should have a mostly hydrogen spectra.  The Dyson sphere would have characteristic spectrum from whatever material was radiating.  For example, an aquarium would have water emissions and glass emissions.  The glass also blocks some frequencies.  If the Aliens use cast iron radiators then we would detect lots of iron.  If they paint the radiators with exterior house paint there will be TiO2 emission.   

It's not that simple, for example a cool star like a red giant does not (usually) show any hydrogen lines and a (macroscopic ) iron object would just radiate more or less like a black body.

Offline high road

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #45 on: 04/21/2017 08:49 AM »
Excellent replies, all of them.

Population density and/or not developing fusion reactors remain the biggest assumptions.

Offline stefan r

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Re: Could Fast Radio Bursts Be Powering Alien Probes?
« Reply #46 on: 04/23/2017 05:15 AM »

So how would we know wether we're looking at a red (super)giant or a main sequence star of the same luminosity surrounded by a radiator Dyson swarm approaching the density of a full Dyson sphere?

Their spectra would be completely different.

A red giant should have a mostly hydrogen spectra.  The Dyson sphere would have characteristic spectrum from whatever material was radiating.  For example, an aquarium would have water emissions and glass emissions.  The glass also blocks some frequencies.  If the Aliens use cast iron radiators then we would detect lots of iron.  If they paint the radiators with exterior house paint there will be TiO2 emission.   

It's not that simple, for example a cool star like a red giant does not (usually) show any hydrogen lines and a (macroscopic ) iron object would just radiate more or less like a black body.

Hydrogen has Humphrey lines.  Should be peak intensity near room temperature.  The Balmer series is missing in cool red giants.  Even the sun is missing the Lyman series.  Other elements (and compounds) have various emissions.

Infra-red can be hard from inside earth's atmosphere. 

On the thread topic: It would be nice if most astronomy publications included speculation on the maximum size of civilizations that could be in the image (or data).  Another paragraph on ways a civilization 0.1 higher up the Kardashev scale could camouflage. 

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