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Have we already been visited by aliens?

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Re: Have we already been visited by aliens?

#271

Post by vladTheInhaler »

naikrovek wrote: post #270
matteocantiello wrote: post #231

Earlier quoted context omitted.

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

Pollution capable of completely killing the dominant species of a planet would last a long time after the creation of that pollution ended. The pollution would vastly outlive the polluters, so it would be detectable for some time after their demise, especially if anything they automated also polluted. That stuff would continue to pollute after its creators all died, at least a bit. Also, it seems that the chance of d…

The phrases "a long time", "some time", and "at least a bit" are doing a lot of heavy lifting there. Oxygen has been in the Earth's atmosphere for over 2 billion years. How long, roughly, is "some time"?

Re: Have we already been visited by aliens?

#272

Post by totalZero »

eloff wrote: post #215
ntsplnkv2 wrote: post #181

Earlier quoted context omitted.

This is a good thing. If we entertained every crackpot theory we would waste tons of time. it's good for there to be some gatekeeping. Of course sometimes they're wrong - but so what? That will come out if there is actual evidence.

There is a balance here, you are correct, but I think we currently skew too far toward gatekeeping. Too little gatekeeping means trouble finding the signal through the noise and time wasted on dead ends. Too much and good ideas get neglected or squashed for far too long. There is a cost to both.

Unfortunately, gatekeeping is essential to academia. Ask anyone who wants to publish a finding independently, or read a paper for free without being associated with an institution. Heck, ask the undergrads who paid tens of thousands of dollars for Zoom classes that have MOOC alternatives alternatives.

> Too little gatekeeping means trouble finding the signal through the noise and time wasted on dead ends.

Much time is supposed to be spent on dead ends anyway. That's the way the corpus matures, not to mention an inevitable result of peer review (no need to review anything if all the research product is perfect). Research is a search; imagine running BFS without expecting to encounter dead ends.

Re: Have we already been visited by aliens?

#273

Post by stefanmichael »

matteocantiello wrote: post #231
eloff wrote: post #45

Earlier quoted context omitted.

> I don't think very many people are saying it is impossible that Oumuamua was an alien construct and actively discouraging science based on the idea it could be. Actually yes. You'll be laughed out of the virtual room, not get funding, and potentially damage your career. As he points out in his interview with Lex (linked elsewhere in the comments here) is fine to propose a multi billion dollar experiment to detect o…

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

I think that you might be right but it would be more conclusive as evidence than detecting just oxygen. CFCs are not something that occurs spontaneously in nature, so essentially if we did get a positive result it would be meaningful.

To your point getting strictly negative results would not necessarily mean anything one way or the other.

Re: Have we already been visited by aliens?

#274

Post by stefanmichael »

naikrovek wrote: post #270
matteocantiello wrote: post #231

Earlier quoted context omitted.

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

Pollution capable of completely killing the dominant species of a planet would last a long time after the creation of that pollution ended. The pollution would vastly outlive the polluters, so it would be detectable for some time after their demise, especially if anything they automated also polluted. That stuff would continue to pollute after its creators all died, at least a bit. Also, it seems that the chance of d…

I thought this might be the case as well but at least for CFCs the lifespan without replenishment from human pollution is only about 140 years. so "a bit" for this particular circumstance is not very long at all in the eyes of the universe

Re: Have we already been visited by aliens?

#275

Post by zelon88 »

matteocantiello wrote: post #231
eloff wrote: post #45

Earlier quoted context omitted.

> I don't think very many people are saying it is impossible that Oumuamua was an alien construct and actively discouraging science based on the idea it could be. Actually yes. You'll be laughed out of the virtual room, not get funding, and potentially damage your career. As he points out in his interview with Lex (linked elsewhere in the comments here) is fine to propose a multi billion dollar experiment to detect o…

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

I believe that we've probably altered the geography of Earth to an extent that it would be trivially easy to determine from great distance that it was once inhabited by intelligent beings. Even if all of our cities are gone, the mineral deposits left behind would be so concentrated. Nevermind the nuclear endeavors.

We were able to detect dinosaurs on our own planet 65 million years after they went extinct, and they didn't even pollute anything.

Re: Have we already been visited by aliens?

#276

Post by matteocantiello »

naikrovek wrote: post #270
matteocantiello wrote: post #231

Earlier quoted context omitted.

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

Pollution capable of completely killing the dominant species of a planet would last a long time after the creation of that pollution ended. The pollution would vastly outlive the polluters, so it would be detectable for some time after their demise, especially if anything they automated also polluted. That stuff would continue to pollute after its creators all died, at least a bit. Also, it seems that the chance of d…

Why would the pollution vastly outlive the polluters? It's not obvious to me. Mixing and recycling timescale of an atmosphere seem very short compared to other relevant timescales of the problem. Impactors, volcanic eruptions... the memory of the atmospheric impact of those events is in the sediments, not the air we breathe (e.g. KT boundary). Finally, civilizations that do not destroy themselves in the short-lived polluting era should move to a clean nuclear fusion era. We are probably ~50-100 yrs away if we don't fuck up.

Re: Have we already been visited by aliens?

#277

Post by _carbyau_ »

PaulDavisThe1st wrote: post #235
stretchcat wrote: post #180

Earlier quoted context omitted.

Every advancing civilization will eventually create an internet. Once they do that, interstellar travel is off the table. Advanced civilizations stay closely packed because they cannot tolerate latency once they get a taste for near instant communication.

Given that serious interstellar travel really requires FTL transport, I suspect that the two are rather closely connected.

So Competitive Quake/Counter Strike/ThingsKidsPlayTheseDays:-) will fund research into FTL transport for Sadly, I could see it. Some billionaire somewhere wants "The Best" latency numbers and wants it on their yacht...

Re: Have we already been visited by aliens?

#278

Post by LargoLasskhyfv »

ncmncm wrote: post #112
6gvONxR4sf7o wrote: post #64

Earlier quoted context omitted.

There seems to be a giant mismatch about what side is open minded. People who think its most likely aliens think it’s closed minded to assign that low probability, presumably because we’re this tiny corner of the universe. People who think it’s most likely not aliens Think it’s closed minded to assign everything else low probability, presumably because aliens are a tiny corner of everything else. Is it a misapplicati…

Their best future course is to stop sniping at one another. It is possible that it's aliens. It is possible that it's not. We don't have enough evidence even to estimate probabilities, so anything further is pure speculation. Speculation is a look that wears no better on conservatives than on radicals. There is hardly a field to be found where young radicals are not promoting evidence for what the tenured consider an…

https://en.wikipedia.org/wiki/Planck%27s_principle

Re: Have we already been visited by aliens?

#279

Post by raggi »

TeMPOraL wrote: post #46
excitom wrote: post #11

Such an object would function as a sail—one powered by light, rather than by wind. The natural world doesn’t produce sails; people do. What about jellyfish that move about the oceans pushed by wind?

It's a weird statement that confuses the purpose of an object with what an object does. Purpose exists only in our heads; natural objects don't have one. There is no tag attached to atoms. In other words, anything that behaves as a sail would, can be called a sail. And there are plenty of objects around us that behave as sails, not made such by humans, or made so unintentionally.

Evolution derives purpose from experimentation. It is not intent driven design, it is experiment driven design, but many aspects of persistence through evolution are nonetheless purposeful. If an adaptation is significantly successful, it becomes prominent in the created population and there is a reason for it - that is the noun, purpose. This would be different if you said "have purpose" instead of "the purpose".

Re: Have we already been visited by aliens?

#280

Post by matteocantiello »

stefanmichael wrote: post #273
matteocantiello wrote: post #231

Earlier quoted context omitted.

I thought the idea of searching for industrial pollution was actually a pretty bad one. We've been polluting at detectable levels for just ~100 years. And if we keep doing it we'll likely wipe us out in a few hundred more. Overall it seems very likely industrial pollution is a very short-lived phase of any civilizations, so chances of detecting this signature are tiny.

I think that you might be right but it would be more conclusive as evidence than detecting just oxygen. CFCs are not something that occurs spontaneously in nature, so essentially if we did get a positive result it would be meaningful. To your point getting strictly negative results would not necessarily mean anything one way or the other.

Yes, I agree with the point that Oxygen is not answering the question definitively. The issue is that say, you build a very, very expensive space telescope and you have to decide if you want it to look for Oxygen or CFC. CFC is a shot in the dark: likely you won't see anything (see my previous comment). Which means likely no data, no PhD thesis, nothing. You pretty much wasted a few billion dollars and you're not ruling out much because what if civilizations only use chemical energy sources for ~200 yrs, then they all switch to nuclear fusion? On the other hand is likely Oxygen will show up as a signature in some exoplanets, and a lot of new understanding about exoplanet atmosphere and geology would follow. Which, among many other things, might help us narrowing down planets where to look for life and how. And next iteration of instruments we might be able to really discover life. So this is why review panels do opt for choices that are more likely to benefit the scientific community at large. It might sound a bit incremental at first, but it's how progress is made. This said, it's not like astrophysicists are not thinking about detecting technosignatures in exoplanetary spectra, see e.g. 3.2 in https://www.liebertpub.com/doi/10.1089/ast.2009.0371 and e.g. https://elib.dlr.de/119683/1/1803.05179.pdf
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