Possible life on Venus.

[bilateralrope]

A podcast I listen to is the Daily Space, which is daily astronomical news. Yesterday they had an episode on the recent discovery of phosphine in the atmosphere of Venus.

Phosphine found in Venus clouds leads to more questions

Sep 15, 2020 | Astrobiology, Daily Space, Venus | 0 comments

Today has one story and only one story. But it is the kind of story where I want all of you to look around and put into your mind where you are right now because this may be the first day we really admit that there could be life elsewhere in our solar system.

Today, a peer-reviewed paper was published in the journal Nature Astronomy announcing that a molecule considered to be biosignature for life has been found in the atmosphere of Venus. This molecule, phosphine (PH3) has no known, naturally occurring sources capable of creating the amount of phosphine that is being seen other than anaerobic life. The implication is that there is chemical evidence of life within the atmosphere of Venus. Such a finding had previously been theorized down to the prediction of phosphine. Observational confirmation of these theories comes from both the Atacama Large Millimeter/submillimeter Array (ALMA) and the James Clerk Maxwell Telescope. Jane Greaves is the lead author of this work.

Since the 1990s, NASA and other funding agencies have supported researchers who are trying to define the observable signatures of life in all its stages. From chemical imbalances in an atmosphere to technological signatures such as infrared excess, researchers have put out paper after paper stating, “If you see these things, life has probably found a way.”

Phosphine is a chemical that, on Earth, can be created through industrial processes, but naturally occurs only as a byproduct of anaerobic life – life that thrives without oxygen. It is created through the breakdown of organic materials. It’s thought that phosphine in modest amounts will be detectable out to an order of ten lightyears. That will allow life in the atmospheres of warm, gassy planets to potentially be detectable using the James Webb Space Telescope. While this observation will be challenging, taking up to ten hours or more of telescope time, it is doable.

Here’s the thing: phosphine requires an atmosphere, but it doesn’t require an atmosphere in another solar system. So while people have been figuring out that phosphine can be used to find life in other solar systems, other researchers, including Planetary Science Institute’s own David Grinspoon, Massachusetts Institute of Technology’s Clara Sousa-Silva and Sara Seager, and NASA’s David J. Smith, have all been part of research looking at the possibility of phosphine being produced by life existing in the atmosphere of Venus.

In recent months, we’ve seen paper after paper and popular article after popular article on the topic of possible life in Venus’s atmosphere. That said, I have to admit that I haven’t read any of those articles because I, for one, was in the “there is one place there can’t be life, and that is Venus” camp. It appears I lack creativity in my own thinking. This means I’m playing a whole lot of catch up on the science behind this story.

These papers all made careful predictions based on some simple facts: Venus has a mean surface temperature of 737 K (464°C; 867°F). At an altitude of 47.5-50.5 kilometers, those spacecraft-melting temperatures drop, so that at that higher altitude, the temperature is just 60°C and the pressure is one atmosphere, the same pressure that we have here at sea level on Earth.

At lower levels down in the atmosphere, things ramp up. They get worse, but that mid-altitude temperate region allows us to begin to imagine a potential cycle where life (microbes) has the ability to billow up through gravity waves – waves in the atmosphere of Venus. And then, as they rise, they seed moisture around them. As the amount of moisture grows, within this moisture, life can do life things until eventually, the droplet gets too big to be supported by the air, and gravity begins to pull it down.

Now the way this gets imagined is you have, down at the lowest levels around 33 kilometers, a temperature that is capable of desiccating any life that gets down there. At this lower point in the cycle, you have spores. These are in the haze layer of Venus that we don’t really understand. And then rising up out of this haze layer, those spores collect moisture around them, and as they arise and build that droplet, the spores come back out and are capable of going through their biotic processes of replication. Eventually, the droplets get too big and begin to fall down. As these droplets fragment, the life desiccates back down to the spores.

This is a life cycle.

Now, this isn’t the first work to consider the possibility of life on Venus. This is the first work to predict phosphine, which has now been seen, and to describe a life cycle within this atmosphere. But there has been other work that said there could be life as an explanation to what we’re seeing on Venus.

Just over a year ago, on August 26, 2019, The Astronomical Journal contained an article by Yeon Joo Lee and collaborators. They pointed out that the dark albedo features in Venus’s atmosphere appeared to not be explainable. According to Lee: The particles that make up the dark splotches, have been suggested to be ferric chloride, allotropes of sulfur, disulfur dioxide and so on, but none of these, so far, are able to satisfactorily explain their formation and absorption properties.

While Lee wasn’t able to explain the dark splotches with these normal means, sometimes you have to look beyond chemistry to biology. Collaborator Sanjay Limaye notes that: Observations of these particles show that they are about the same size and have the same light-absorbing properties of microorganisms found here on Earth.

These dark splotches were earlier pointed out by noted biophysicist Harold Morowitz and astronomer Carl Sagan as potentially being microscopic life.

So here we have two radically different stories. We have today’s breaking news of the observational detection of the predicted phosphine in Venus’s atmosphere seen with two telescopes. And that phosphine exists in a large enough amount that it can’t be explained via photochemistry – chemistry in the atmosphere driven by interactions with sunlight. It can’t be explained in the amount that it exists by geochemical processes within Venus, as far as we know.

We see the paper from a year ago postulating that maybe the dark spots could be microscopic life.

This is all building on so many different things. The frustration is that we can’t go out and say anything definitively. But here is one final thought I want to put into your heads. Recently, our view of the history of Venus has begun to change as the possibility that 750 million years ago, it was capable of supporting life as we know it on its surface. That its climate was radically different. That there were liquid water seas.

Something happened. Something triggered a runaway greenhouse effect that destroyed this world for most life.

Let’s consider that 750 million years ago when that catastrophic event happened, what was going on in our world. At that point, we had single-celled organisms capable of coming together in colonies to form sponges. We had, at 730 million years ago, the beginnings of comb jellies. We had life on this world. And it’s possible that there was life at the same time on Venus, and that, as that environment collapsed, it’s possible that some of the microbes took to the air and found a way to keep on going. Because life, maybe, does find a way.

Now it doesn’t have to be a story that goes that way. It could be that there is geochemistry on Venus that defies everything we currently understand, and life isn’t necessary. It could be that there is photochemistry in the complex atmosphere of Venus that does things that we aren’t creative enough to figure out, and life is not necessary. It’s possible that life formed in those clouds, originating there.

This is something that can’t happen on our world. Here on Earth, our clouds are wispy. They’re transitory. There is no standing moisture layer in the Earth’s atmosphere with persistent droplets capable of supporting life thriving in those droplets. We can’t do this. But on Venus, there is that persistent moisture; there is that possibility. We can’t know: is this unknown chemistry or is this potentially life not-to-distant from what we understand on Earth? We can’t know what the solution is until we go there and we’re able to somehow fly through the clouds and see in our samples the life under our microscopes.

Currently, there are no planned missions to Venus. Well, there are planned missions, but there are no funded, nuts-and-bolts, being put together, in the process of being built research spacecraft coming from a government-funded agency. Rocket Labs is looking to do a 15-kg microsat that would have the capability of carrying three kilograms of instrumentation with it. It’s probably not going to be what we need to say, “Yes, it’s life.”

Hopefully, these discoveries will motivate those spacecraft to come in the not-too-distant future.

This is a kind of amazing day. Today may be the day that we all look back on and say, “This is when we first realized we may not be alone in this universe.” And the place I thought most inhospitable in our solar system may be where that life is first discovered.

Remember today.

Links to listen to the podcast, or to their sources, can be found following the link I posted above.

[madd0ct0r]

Fascinating stuff. Thank you for posting.

[darth_timon]

If life can exist in the atmosphere of Venus, I'd be willing to assume it can exist virtually anywhere

[Captain Seafort]

If life can exist in the atmosphere of Venus, I'd be willing to assume it can exist virtually anywhere

I'd say the same about hydrothermal vents.

[SolarpunkFan]

For those of us who ascribe to the great filter hypothesis, this becomes concerning (as does the Martian methane detections).

[bilateralrope]

For those of us who ascribe to the great filter hypothesis, this becomes concerning (as does the Martian methane detections).

I've noticed that people who talk about the Fermi Paradox make a lot of assumptions about how easy intelligence would be to detect. What information I've been able to find tells me that, even if there was a planet putting out signals as strong as we have around proxima centuari, those signals would be too weak for us to detect. Analyzing exoplanet atmospheres is a bit better. As in, I recall something about a satellite being launched in the next few years that could analyse them out to 100 light years.

So that makes the answer to the Fermi Paradox quite simple: What we see is consistent with their being other intelligent civilizations out there. Because we don't have the capability to see them.

[Broomstick]

Simple, single-cell life might be common. It then becomes a question of whether or not multi-cellular life is common or not.

[Eternal_Freedom]

That's a question I get asked every single time my astronomy society does any kind of public event. I always explain that it's the wrong question - of course there's other life in the universe, it#s too damn big for us to be all there is (also that's a fantastically arrogant view, that humans are it as far as life goes), the actual question is whether there is intelligent life close enough that we could meaningfully communicate with them. That's a lot more uncertain.

[Sky Captain]

For those of us who ascribe to the great filter hypothesis, this becomes concerning (as does the Martian methane detections).

I've noticed that people who talk about the Fermi Paradox make a lot of assumptions about how easy intelligence would be to detect. What information I've been able to find tells me that, even if there was a planet putting out signals as strong as we have around proxima centuari, those signals would be too weak for us to detect. Analyzing exoplanet atmospheres is a bit better. As in, I recall something about a satellite being launched in the next few years that could analyse them out to 100 light years.

So that makes the answer to the Fermi Paradox quite simple: What we see is consistent with their being other intelligent civilizations out there. Because we don't have the capability to see them.

An issue with Fermi Paradox is if some technological civilization developed just few million years earlier and spread out into our Galaxy we would have detected anomalies like Dyson swarms or some unexplainable high energy phenomena. A civilization 10 - 20 million years older could have colonized entire Galaxy by now even if traveling by fairly slow fusion starships. It doesn't have to be living beings it could be some kind AI self replicating technology run amok and spreading out even if civilization of origin is long dead.

Even we are first technological civilization in our Galaxy there are millions of other galaxies not too far. If some aggressive expansionist civilization or self replicating tech would have developed there some 100 million years earlier we would have noticed something weird like too much infrared radiation coming from their Dyson swarms.

[bilateralrope]

issue with Fermi Paradox is if some technological civilization developed just few million years earlier and spread out into our Galaxy we would have detected anomalies like Dyson swarms or some unexplainable high energy phenomena.

What assumptions are you making when you say they would have made Dyson swarms ?

[Batman]

The actual actual question is whether there is intelligent life close enough that we could meaningfully communicate with them yet dumb enough to want to.

[Solauren]

The Femi Paradox shouldn't be "where is everyone", it should be "how do we find it."

[Formless]

Indeed, I've always thought it would be better phrased as the Fermi Question because that's quite literally how Fermi phrased it. "Where are the aliens?" If there is an as yet unknown answer to the question, don't call it a paradox.

issue with Fermi Paradox is if some technological civilization developed just few million years earlier and spread out into our Galaxy we would have detected anomalies like Dyson swarms or some unexplainable high energy phenomena.

What assumptions are you making when you say they would have made Dyson swarms ?

A ton. Fusion ships, self-replicating technology, and Dyson swarms are all very pie-in-the-sky ideas and any one or all of them might be impossible or superseded by other technologies that other civilizations have come up with that we are only now imagining and which would not be so easily detected over interstellar distances. For instance, a fusion drive that can be seen over vast interstellar distances might be considered laughably leaky and inefficient by any civilization actually capable of interstellar trips. It might even be that warp drives are actually possible and practical to make once you understand dark matter and dark energy, even if they have to go at or below light speed; and because they move a ship by manipulating spacetime itself rather than exploiting Newton's third law of motion, you wouldn't see an exhaust plume. Instead you would have to look for microlensing events that aren't easily distinguishable (if distinguishable at all) from dark massive objects like rogue planets. If they aren't possible, we might have to question whether it is even practical or desirable for any civilization to leave its stellar back yard, with the possible exception of civilizations around multiple star systems or star clusters.

There are also multiple applications for a technology called a Kugelblitz: that is, an artificial black hole created by concentrating laser light into a very tiny point until it traps its own energy behind an event horizon. This is far less of a leap than warp drives but has similar consequences for the Dyson Swarm assumption. Because of Hawking radiation these become a way of converting mass into potentially useful energy in a very different way than matter-antimatter annihilation. One application is an alternative to a fusion torch drive, but another is an alternative to the Dyson Swarm. To summarize PBS Spacetime's video, a Dyson Swarm takes a the mass of the planets Mercury, Venus, Mars and several moons of the outer solar system to build. While it might be possible (especially if you grant self-replicating robotics), its obviously impractical. Furthermore, the swarm is actually quite inefficient both in the sense that a star isn't the most efficient at burning fuel, and in terms of the mass of the entire engine. Again, we're talking about converting several planets into solar collectors, when we could instead colonize them or use them to create space colonies. In general, I tend to think living creatures would prefer to make real estate over collecting energy for more abstract purposes.

However, a partial swarm could create the lasers needed to make a massive kugelblitz (well, not like naturally occurring stellar black holes, but you get the idea), and from there its just a matter of shoving matter into the black hole and harvesting the emitted heat and Hawking radiation. In theory, not only does this convert 100% of the mass of the fuel into energy, its so much more efficient that you could conceivably power a Kardeshev type III(!) civilization using only the matter available in the Solar system. In contrast, most people conceive of Type III civilizations as requiring the colonization of an entire galaxy and conversion of countless star systems into Dyson swarms. That's a huge difference in energy efficiency. And we would only have to take apart Mercury (perhaps not even entirely) to make the requisite lasers to manufacture Kugelblitz black holes on an industrial scale. This would be far harder to detect than a full scale Dyson swarm and the resulting black hole reactors would be basically invisible to terrestrial astronomers at interstellar distances. At that point, who needs to send out self replicating robots to other solar systems? You can always just make a Kugelblitz reactor and surround it with a series of O'Neil cylinders and you have yourself a civilization in miniature. So long as you can find sufficient matter to feed the black hole you can drift into deep space and never worry about the death of your star. And because e=MC^2, that shouldn't be too hard to do compared to launching ships at relativistic speed. But if you want, those same kugelblitz reactors can be turned into rocket engines to power starships.

Of course, self replicating robots aren't a game changer without an interstellar engine capable of leaving their solar system. If the ship is too slow, the electronics will not survive the cosmic radiation that permeates deep space, and if it isn't sufficiently armored, space dust will slowly destroy it like a mountain being weathered down by the rain. If you do have such engines, you probably also have the radiation protection and the means to sweep away interstellar dust. Assuming the engine itself isn't visible because solar sails and other "practical" engine types are actually pretty hard to spot, you might think to look for the telltale sign of a laser broom sweeping space ahead of the ship; but, it might be too small a wake for us to identify or, again, to distinguish from a rogue planet. As PBS spacetime points out, its never aliens until all other explanations have been exhausted. Even for as exciting as the Venus detection is, he's still cautiously putting his money on an unknown geological process producing the gas because of this principle.

[Solauren]

And that's just with technologies we can envision and theorize based on known science.

Who knows what is possible really? For all we know, there is a galactic civilization out there that surrounds low tech solar systems with hologram fields to hide all there activity until they judge said systems ready to see the truth.

Then again, there is also the possibility that we're the most advanced society in the galaxy, possibly universe, and we won't be able to find life outside of our world for a few more decades (Mars, Venus), to centuries (other solar systems).

[SolarpunkFan]

I apologize for putting the thread off topic.

More recent news, there might not be a phosphine anomaly after all:

Context: ALMA observations of Venus at 267 GHz have been presented in the literature that show the apparent presence of phosphine (PH3) in its atmosphere. Phosphine has currently no evident production routes on the planet's surface or in its atmosphere.
Aims: The aim of this work is to assess the statistical reliability of the line detection by independent re-analysis of the ALMA data.
Methods: The ALMA data were reduced as in the published study, following the provided scripts. First the spectral analysis presented in the study was reproduced and assessed. Subsequently, the spectrum was statistically evaluated, including its dependence on selected ALMA baselines.
Results: We find that the 12th-order polynomial fit to the spectral passband utilised in the published study leads to spurious results. Following their recipe, five other >10 sigma lines can be produced in absorption or emission within 60 km/s from the PH3 1-0 transition frequency by suppressing the surrounding noise. Our independent analysis shows a feature near the PH3 frequency at a ~2 sigma level, below the common threshold for statistical significance. Since the spectral data have a non-Gaussian distribution, we consider a feature at such level as statistically unreliable that cannot be linked to a false positive probability.
Conclusions: We find that the published 267-GHz ALMA data provide no statistical evidence for phosphine in the atmosphere of Venus.

With the usual caveat that this argument is still tentative pending further verification, of course.

[Formless]

And that's just with technologies we can envision and theorize based on known science.

Who knows what is possible really? For all we know, there is a galactic civilization out there that surrounds low tech solar systems with hologram fields to hide all there activity until they judge said systems ready to see the truth.

Yes, and for all we know you are a butterfly dreaming he is a man, but generally real scientists reject this kind of nonsense as unfalsifiable and unscientific reasoning.

Seriously, I HATE HATE HATE any answer that devolves into Cartesian skepticism. All Cartesian skepticism ever gave us was creationist apologetics and empowered various woo-meisters like modern Flat Earthers with pseudo-scientific excuses for their bullshit. Its far, far too hard for the average person to understand why this line of reasoning is the philosophical equivalent of dividing by zero, so I wish people would stop bringing it up. To see real scientists propose such garbage proposals gives me a headache. The Simulation Argument as an answer to the Fermi paradox is not only wrong, taken to its extremes its not even wrong.

With the usual caveat that this argument is still tentative pending further verification, of course.

Statistical arguments often change as more data comes in, so its worth pointing more radio telescopes at Venus to see what shakes out. Furthermore if I understand correctly, their argument is that it is statistically unreliable because of how they smoothed out the noise; that doesn't mean it is inaccurate, however. It means they need a better noise cancelling algorithm. There could still be a signal there despite the potential for a false positive in the current method. There are probably other methods for detecting phosphine in the planet's atmosphere (the most obvious being to simply send a probe; something we can do with Venus but not an exoplanet), but if this method turns out to be giving false positives, we will at least know better than to use it on exoplanets in the future. The whole point of using Venus as a test case was to calibrate the instruments, since it was somewhere where phosphine was not expected to exist. So this paper shouldn't be taken as the end to the story. At the end of the day good science is always empirical and instrumental, not purely mathematical. This observation was always meant to be taken as preliminary. That's why the professional scientists were still hedging their bets on a non-biological explanation.

[SolarpunkFan]

This observation was always meant to be taken as preliminary. That's why the professional scientists were still hedging their bets on a non-biological explanation.

Of course. The hypotheses are currently just that: hypotheses.

[Sky Captain]

issue with Fermi Paradox is if some technological civilization developed just few million years earlier and spread out into our Galaxy we would have detected anomalies like Dyson swarms or some unexplainable high energy phenomena.

What assumptions are you making when you say they would have made Dyson swarms ?

If you need a ton of power in space then using a star you already have is the most obvious way. Even here on Earth with clouds and night solar power is becoming very cheap. In space with 24/7 sunlight it would be very hard to beat

There are also multiple applications for a technology called a Kugelblitz: that is, an artificial black hole created by concentrating laser light into a very tiny point until it traps its own energy behind an event horizon.

If deployed on mass scale this would also alter spectral characteristics of a star system. All that energy would end up as infrared radiation anyway unless there are some way to cheat thermodynamics. Good question would be how much excess energy can be produced in this way and still not reach a threshold that would make astronomers scratch their heads trying explain why this star has such weird spectral lines. Or if deployed in deep space why this region seems to be warmer than background,

However, a partial swarm could create the lasers needed to make a massive kugelblitz

This also raises good question what is the level at which Dyson swarm would become noticeable across interstellar distances?

If we assume advanced civilizations are hard to spot we also must assume that they don't throw around stellar levels of energy, don't build megastructures, don't make weird high energy physics experiments producing strange radiation patterns, basically do nothing that makes their region of space look different than natural background.

[Formless]

If deployed on mass scale this would also alter spectral characteristics of a star system. All that energy would end up as infrared radiation anyway unless there are some way to cheat thermodynamics. Good question would be how much excess energy can be produced in this way and still not reach a threshold that would make astronomers scratch their heads trying explain why this star has such weird spectral lines. Or if deployed in deep space why this region seems to be warmer than background,

I think you have missed a point here. The problem isn't detecting the signal. The problem is distinguishing an artificial signal from a natural phenomenon. With the original Dyson Swarm idea, it was distinguishable because the infrared signal is accompanied with significant, non-periodic dimming of the star, and the non-periodic nature of it (constant dimming is assumed) we can rule out a planet as the cause. And even then, as Tabby's Star shows, natural phenomena like swarms of comets can also look like a Dyson swarm, if you squint hard enough. Astronomers decided it was a swarm of natural objects because the dimming wasn't constant, it just didn't follow a consistent pattern. A mere infrared signal that is not accompanied with significant dimming cannot be attributed frivolously to intelligence because intelligence is a catch-all explanation. Hence, an explanation of last resort.

This also raises good question what is the level at which Dyson swarm would become noticeable across interstellar distances?

If we assume advanced civilizations are hard to spot we also must assume that they don't throw around stellar levels of energy, don't build megastructures, don't make weird high energy physics experiments producing strange radiation patterns, basically do nothing that makes their region of space look different than natural background.

Why should we assume they are throwing around cosmic levels of energy? At what point do they have sufficient energy to do the things their civilizations needs to do? One problem with the Kardeshev scale is that it assumed that energy consumption would scale upwards constantly because demand for energy needs scaled up with it, but did not take into account advances in technology that makes energy consumption more efficient, nor changes in technology that reduces demand for energy. Technology after all isn't about machines and tools, but about manipulating the world to achieve goals our natural tools (i.e. human hands) cannot achieve alone. The efficiency problem is no idle thing, if we had cheap, room temperature superconductors right now our power grid would become vastly more efficient than it currently is because losses due to resistance in electrical cables would drop near zero. Thus we could achieve similar things to a Kardeshev I civilization without ramping up our energy production to the degree predicted by the scale. And as for the second point, technology which reduces demand for energy in the first place, consider how houses are built now vs how they used to be built before the advent of modern insulation. Without proper insulation, to keep a house warm you need to constantly burn fuel. With insulation, that fuel can be conserved while maintaining the same temperatures in winter. Insulation is a technological advancement that is intended to reduce energy production by preventing thermal energy loss. We still burn fuel to heat our homes, but we don't need to burn as much of it. Any excess fuel burnt to heat houses nowadays can be attributed to a desire for luxury.

Really, before we ask why we aren't seeing K2 and K3 civilizations, we must first ask what they need all that extra energy production for. Like I said before, intelligent living beings are more likely in my opinion to want to take apart planets and planetoids to build real estate rather than reactors. The simple reason is that a space colony has obvious utility as a home and center of economic or cultural activity. The reactor is only useful when attached to a colony or some kind of engine doing economically useful things, like churning out economic goods or doing vital science. But something ridiculously energy expensive like colonizing other stars? There may be no obvious economic or cultural incentive to spend the resources and energy needed in making that happen. Unless, as I said before, the civilization evolved in a multiple star system or star cluster where the stars are closer together than our own stellar neighborhood. Once you have a civilization able to drift into space without worrying about the death of their star, you would be hard pressed to detect their infrared signature through the interstellar medium. Right now we can't even detect rogue planets except in the rare instance that they cause a microlensing event in front of another star. Why should we be able to detect free-floating Kugelblitz fueled civilizations? At some point, energy stops being an issue for them, so they just need to stay at a maintenance level of fuel consumption to keep the black hole alive. They can even drag the machinery to make more kugelblitz reactors with them until they can find another star to install it around, since the same technology underpinning the reactor can be used as a rocket.

[Sky Captain]

I think you have missed a point here. The problem isn't detecting the signal. The problem is distinguishing an artificial signal from a natural phenomenon.

That was my main question. What is the point at which artificial signal would become unexplainable by any known natural phenomena. If advanced civilizations never reach that point then they could stay undetected forever. Obviously a distance and level of activity would be a major factor,s. A megastructure or active interstellar traffic around some of our closest stars would be much more noticeable than around some random star 30 000 light years away. A rogue Von Neuman swarm consuming entire galaxy would be detectable across intergalactic distances.

Why should we assume they are throwing around cosmic levels of energy?

Some weird physics experiment maybe. If energy is cheap enough all kinds of applications may show up.

The efficiency problem is no idle thing, if we had cheap, room temperature superconductors right now our power grid would become vastly more efficient than it currently is because losses due to resistance in electrical cables would drop near zero. Thus we could achieve similar things to a Kardeshev I civilization without ramping up our energy production to the degree predicted by the scale. And as for the second point, technology which reduces demand for energy in the first place, consider how houses are built now vs how they used to be built before the advent of modern insulation. Without proper insulation, to keep a house warm you need to constantly burn fuel. With insulation, that fuel can be conserved while maintaining the same temperatures in winter. Insulation is a technological advancement that is intended to reduce energy production by preventing thermal energy loss. We still burn fuel to heat our homes, but we don't need to burn as much of it. Any excess fuel burnt to heat houses nowadays can be attributed to a desire for luxury.

These are good points however in our situation we are kind of forced to increase our energy efficiency because not doing so would fuck up our biosphere even more and we only have limited amounts of fossil fuels to burn. In space however there are no such constraints although engineering considerations still apply There is no point of making something needlessly inefficient if that makes waste heat management too difficult. Reverse also is true if making some device or process very efficient is possible but require huge effort, but energy is almost free then no point of doing that if problem can be solved with some extra solar collectors and radiator fins.

Really, before we ask why we aren't seeing K2 and K3 civilizations, we must first ask what they need all that extra energy production for. Like I said before, intelligent living beings are more likely in my opinion to want to take apart planets and planetoids to build real estate rather than reactors. The simple reason is that a space colony has obvious utility as a home and center of economic or cultural activity. The reactor is only useful when attached to a colony or some kind of engine doing economically useful things, like churning out economic goods or doing vital science. But something ridiculously energy expensive like colonizing other stars? There may be no obvious economic or cultural incentive to spend the resources and energy needed in making that happen.

An interstellar colonization mission wouldn't be that difficult for civilization already having well developed star system. Converting some 0.00001 percent of solar output into laser energy to drive lightsail starship isn't that hard if you already have all the infrastructure in space. Maybe even within reach of rich individuals or organizations. Heck even our civilization has reached the point where individual billionaires are making their own space programs.

What could happen to other civilizations is just speculation. Maybe virtual reality is the easy way and civilizations stop caring about real space development if virtual reality is so good it is indistinguishable from the real thing. Then there would be no energy signatures detectable across the galaxy because computers don't require much resources to run.

[Jub]

The argument for colonization, regardless of current need, is that it is beneficial to the long term* health of your society to control as much mass as you can. Hence why you would want to colonize and star lift solar systems and eventually galaxies. Every star you fail to capture is energy you won't have going forward.

This of course depends on very long-term planning, but it doesn't rely on interstellar travel as even if a traditional spaceship can't make it somewhere you can always star-lift your entire system over to the nearest star and expand that way.

*Like after every star has died out long term.

[Formless]

A rogue Von Neuman swarm consuming entire galaxy would be detectable across intergalactic distances.

The problem with Von Neuman probes is that the theory is based on overly simplistic assumptions that do not work in the real world. Namely the theory does not account for the distribution and accessibility of heavy elements needed for high technology, let alone self-replicating technology. We now know that there are many planets with masses in between that of Earth and Neptune, and those planets probably serve to trap much of the heavy elements of the universe underneath a much stronger gravitational field than that of Earth's. The self replicating probe idea requires the probe to constantly seek out sources of fuel and building materials, and find solutions to liberating those resources in order to make more probes. Which means we can compare it quite handily to living organisms. And you know what takes up the vast majority of a living organism's time? Eating! The probe and its offspring would have to contend with not only the vastness of space and surviving constant bombardment by cosmic radiation that could cause serious damage to its electronic brain-analogue (which in turn can be compared to damage to the DNA of a cell for self replication purposes), but it has no ability to identify the low mass objects like asteroids and dwarf planets that it needs to feed on from interstellar distances because of the same physical limitations our own telescopes have to put up with. So the idea of a single self-replicating organism analogue in space is actually pretty ludicrous. It needs an entire infrastructure of specialized machines like telescopes, computer brains, and probably specialized engines that resemble a partial Dyson swarm in order to actually propel itself from system to system in order to actually work. Which I feel confident in saying because I've actually looked into the various forms of interstellar propulsion that have been proposed. All of them require tremendous energy and usually the easiest way to cheat the tyranny of the rocket equation is some kind of beaming propulsion pushing a solar sail; unless, that is, some kind of breakthrough in propulsion happens like the warp drive, and I've already pointed out how warp drives make detection almost impossible. And at the point we're discussing partial Dyson swarms, we aren't talking about a probe anymore, we're back to talking about a civilization. And that gets back to the point that civilizations of living beings may see no advantage of traveling to the nearest stars. Vonn Neuman was so concerned with whether a self-replicating machine was possible he never asked whether they were probable.

Which makes me confident in calling Vonn Neuman probes futurist schmuckbait.

Some weird physics experiment maybe. If energy is cheap enough all kinds of applications may show up.

As far as I'm concerned generalizations like this are so vague they are insufficient to answer the point. If we can't imagine something that actually requires the energy levels of a Type II or Type III civilization, the hypothesis is flawed on a conceptual level. We cannot assess the probability of finding an alien experiment unknowable to our own science.

Reverse also is true if making some device or process very efficient is possible but require huge effort, but energy is almost free then no point of doing that if problem can be solved with some extra solar collectors and radiator fins.

I'm going to disagree with you there, just adding more collectors and radiators is very expensive in terms of mass penalty to the spacecraft its attached to. The energy isn't ever truly free, there is a huge up front cost in making big solar collectors in space, which is one of the reasons we haven't attempted beaming solar power ourselves (the other being the fear of orbital bombardment, of course). Meanwhile, efforts to make existing technologies more efficient in areas like transmission of energy, energy efficiency, and energy demand are a long term investment that could very well have a smaller upfront cost to them. Once you have a superconductor that works at standard temperatures and pressures, working that material into every existing technology isn't too hard, because they will need replacing eventually anyway. As you replace, you upgrade. The upfront cost isn't as daunting when its taking the place of things you were going to throw away eventually anyway. Which incidentally, is probably how our power grid is going to be upgraded, a lot of our current coal fired plants are reaching their planned obsolescence date and even those designs which still burn fossil fuel are likely still more energy efficient than 90% of the existing grid in the US, IIRC.

An interstellar colonization mission wouldn't be that difficult for civilization already having well developed star system. Converting some 0.00001 percent of solar output into laser energy to drive lightsail starship isn't that hard if you already have all the infrastructure in space. Maybe even within reach of rich individuals or organizations. Heck even our civilization has reached the point where individual billionaires are making their own space programs.

Ah, but lightsail starships of the type you are talking about are actually puny. We're talking about something that might very well be the size of a cell phone strapped to a sail the diameter of the moon (and thus far more massive than the payload even if we assume its ridiculously thin). There is no question why we aren't seeing these kinds of ships. Unless the ship is aimed directly at us so that we can see spillage from the laser driving it, its basically invisible.

[bilateralrope]

Converting some 0.00001 percent of solar output into laser energy to drive lightsail starship isn't that hard if you already have all the infrastructure in space.

How do you get your lightsail ship to slow down inside the target system ?

[Jub]

Converting some 0.00001 percent of solar output into laser energy to drive lightsail starship isn't that hard if you already have all the infrastructure in space.

How do you get your lightsail ship to slow down inside the target system ?

Ideally, you'd send something slower to the system first and build a weaker laser there to act as brakes. Otherwise, you could build your solar sail-powered ship with an Orion deceleration phase. Both would require ceasing acceleration earlier than halfway, coasting sail end to the destination system using both blue-shifted light and interstellar particles to slow down somewhat, and then using either a laser built-in system or some form of nuclear propulsion to slow down to speeds where the system's star can capture you.

[SolarpunkFan]

Ideally, you'd send something slower to the system first and build a weaker laser there to act as brakes. Otherwise, you could build your solar sail-powered ship with an Orion deceleration phase. Both would require ceasing acceleration earlier than halfway, coasting sail end to the destination system using both blue-shifted light and interstellar particles to slow down somewhat, and then using either a laser built-in system or some form of nuclear propulsion to slow down to speeds where the system's star can capture you.

Alternatively using a Zubrin-style magsail to slow down, but that might not work for larger/very fast-moving payloads.