There is a tendency in science fiction to see alien life as similar to Earth life. Intelligent life is again similar to us. The problem is that alien life may be profoundly different on just a molecular level. On Earth there are three major branches of multicellular life, animals, plants and fungi, with slime molds a minor branch. If there is complex life on some other planet chances are good it will have few resemblances to any of these. There might be photosynthetic life forms, but even here on Earth there are bacteria with photo active pigments that are orange or violet. So, the planet might not have a green color, but orange or violet. There might be life forms that have motor abilities, but this might be very different from actin-myosin process in muscles. There might be processing networks, but most likely they would not be what we call brains.
The diversity of possible forms is enormous. There might be some life form that has the ability to manipulate matter and energy, or what we might call technology. If they develop the ability to transmit signals by electromagnetic fields then in some ways it is a fair conjecture that they process information according to mathematical rules. Physics is physics, no matter what, or maybe we might ask who, the ET life form happens to be. However, the difference in processing such ET life forms have might map this into something similar to what an encryption code does. In other words, they might be doing and thinking, if thinking is even the right term, the same as we do, but it is expressed in ways that are almost undecipherable. It is also possible there are self-organizing systems that are entirely different from what we call biology. These might exist on planets or they might exist elsewhere, whether in vacuum or on something such as a white dwarf star. LC On Wednesday, May 27, 2020 at 4:27:40 PM UTC-5, Brent wrote: > > > > On 5/26/2020 10:51 PM, Jason Resch wrote: > > > > On Tue, May 26, 2020 at 11:16 PM 'Brent Meeker' via Everything List < > everyth...@googlegroups.com <javascript:>> wrote: > >> >> >> On 5/26/2020 3:33 PM, Jason Resch wrote: >> >> >> >> On Wed, May 20, 2020 at 5:14 PM 'Brent Meeker' via Everything List < >> everyth...@googlegroups.com <javascript:>> wrote: >> >>> >>> >>> On 5/20/2020 6:39 AM, Bruno Marchal wrote: >>> > Hi Jason, >>> > >>> > When you say that Reality is infinite, are you alluding to the >>> > (phenomenological) physical reality? Or the absolute reality? >>> > >>> > With mechanism, it is very plausible that the physical reality is >>> > infinite, as it is a sort of broder of the universal mind (the mind of >>> > the “virgin” universal machine). >>> > >>> > But even with an infinite physical reality, it is unclear if we are >>> > alone or not, in the physical reality. We are numerous in the >>> > arithmetical reality (which can be taken as the absolute one, modulo a >>> > change of universal machinery). But to have alien fellows in the >>> > physical reality, you need some homogeneity in that reality, which is >>> > not obvious at first sight. >>> > >>> > In fact, I get the impression that we might be rare, if not alone. The >>> > probability for life might be as close to zero as von Neumann thought, >>> > but even the possibility of its evolution requires many conditions, so >>> > many that we might be alone in the cosmos (not in the multiverse, as >>> > there we have even doppelangers). >>> >>> I think the evidence suggests that there is a lot of life in the visible >>> universe and even a lot of technological civilizations...but they are so >>> sparse that we are effectively alone. >>> >>> >> Hi Brent, >> >> As promised I've just finished writing about the existence of life and >> intelligent life in the universe. I'd appreciate your thoughts. >> >> Though life could be very rare I describe another possibility, which is >> that it miniaturizes and becomes so unlike and alient to the biological >> life we're familiar with and looking for that we don't notice it. >> >> >> But we do know that even the most microscopic "life", even viruses grow >> and reproduce using the same mechanism at the molecular level as we do: >> DNA, RNA, mRNA, proteins, ATP=>ADp,... That's really the basis for >> thinking that all life on Earth had a single origin. Even archea and >> bacteria use the same metabolic pathways. >> >> > I agree life will likely start in more or less recognizable ways, but I > believe that after a few thousand or million years of being a technological > civilization, it will reach stages that are unrecognizable to us. They will > most likely be non-biological, and non-corporeal, living in virtual > realities. Computers are substrate independent and can take many different > forms. Moreover they can be arbitrarily efficient so long as they are > logically reversible. There need not be any significant heat signature. > > > That's why I said you needed to say what your definition of "life" was at > the beginning. Computers can't be logically reversible and still act > within the universe...so most people would say that can't be life. I'm not > sure a computer can even have thoughts if exists only in a reversible > superposition of states. > > > >> >> https://alwaysasking.com/are-we-alone/ >> >> >> Not just matter, energy, and time. Life needs an entropy gradient. Your >> whole section on "Energy" reads as though energy is consumed. But energy >> is conserved. >> > > Good point. I meant energy in the colloquial sense (energy available for > useful work). Is there a another word I could use for this concept that > isn't as technical/scary sounding as entropy gradient? > > >> It is low entropy (mostly of sunlight) that is "consumed" by turning it >> into higher entropy infrared radiation. The best theories of the origin of >> life postulate alkaline vents as the locus (which are not so hot as >> hydrothermal vents). Have you read Nick Lane's "The Vital Question"? >> > > I haven't. Thanks for the suggestions, I will have to read more about > alkaline vents. > > >> >> I think you make a mistake in jumping right into "what life needs". You >> should first define what you mean by life. Life as we know it: carbon, >> hydrogen based? Anything that reproduces. Anything that >> metabolizes?...what? >> > > You're right, that is an oversight. I will add a definition. Something > like: self-maintaining processes that convey information across generations. > > >> >> It took a billion to two billion years for* eukaryotes* to evolve...not >> multicellular life. Multicellular life only arose 0.6 billion ya. >> > > Thank you, I will correct this. > > >> >> Tardigrades are not going to survive on the Moon...that's fantasy. They >> don't eat rocks. Surface temperature on the Moon near the equator varies >> from -183 degC to +106degC. And there's no protection from occassional >> cosmic ray showers. Tardigrades might survive hours or weeks, but they are >> not going to survive as a species on the Moon. >> > > The Tardigrades were in their tun state where they wrap up their genes to > protect them from radiation and reduce their metabolism by orders of > magnitude. I agree they would not thrive and reproduce on the moon, but > they may exist for perhaps a year (maybe longer?), at least if some landed > in an indentation in the soil where they were shielded from direct > sunlight) and remain revivable. Some recovered tardigrades in the antarctic > were revived after 30 years. I don't know the lower temperatures on the > moon would extend or shorten that time frame. > > >> >> The Drake equation rewritten in terms of "detectable" civilizations is >> wrong because it only considers sending out signals. To be detectable >> there has to be a receiver in the forward light cone. Assuming >> technologically advanced civilizations last 500yrs that means two of them >> have to be withing detection range during that 500yr band. I'm not sure >> what the detection range is within a noisy galaxy but I think it's less >> than 100lyr. One problem is that as communication becomes more >> technologically advance it becomes less distinguishable from noise. >> > > That's true bout going silent with new technologies, and I mention that. I > would say that the Drake Equation is in terms of "detectable in principle" > rather than "detectable in practice". Detecting unaimed broadcasts from > across the galaxy might require planet-sized detection dishes. But > regardless of whether or not two-way communication is possible, the > equation is based on a constant star creation rate. Assuming that constant > rate applies, then even if civilizations appear, broadcast for 500 years, > then wipe themselves out, the total number of presently detectable (in > principle) civilizations should be approximated by the equation. > > > That's very well if you're just aiming to convince people that there are a > lot of civilizations out there in spacetime. But it's useless in answering > Fermi's question. The answer to that question depends on us being a > civilization capable of hearing another one as well as there being another > one near enough in space and time. > > > >> >> "the Arecibo Telescope on the receiving end could pick up the signal >> from a distance of tens of thousand of light years–on the other side of the >> galaxy." >> The other side of the galaxy is a *hundred* thousand light years away. >> > > But we're about midway to the center. Even if they were as far apart as > possible, the farthest they could be from us and still be in the galaxy is > 70K ly. Perhaps I should say across, rather than on the other side to be > more clear. > > >> >> "The vast distances implied by being the only intelligence in the >> observable universe would, for all practical purposes, mean we are alone, >> even if infinite other intelligences exist across our infinite universe." >> I think this is the important take-home point. And it doesn't have much >> to do with the observable universe and how many planets may have life. >> Even the closest stars are already too far away for us to not be alone. We >> might conceivably send a probe to alpha centauri. We might talk to a >> technological civilization 50 light years away...but that would be about >> the limit, 100year send/reply cycle. >> > > For our present state of technology, and biology, where we live as bags of > meat with 100-year lifespans, those distances are inaccessible. But for a > civilization that uploads their minds into starchip-like computer chips, > effectively copying their entire civilization and storing them on each von > Neumann probes as it replicates and spreads, they could build a > civilization that spans the galaxy, and is present in every solar system > (assuming they had the will to). > > >> >> No doubt intelligence is evolutionarily useful...but human level >> intelligence, speech, mathematics, technology? It's not so clear. In fact >> it may be the kiss of death. You used 500yr as the life time of a >> technological civilization...do you think we'll make another 400yrs? >> > > I think if we can survive the next century, we can last another million > years. But I hold that optimism only because I see super-intelligence > arising in that time, which could intervene to relieve us from making > suicidal missteps. > > > More to the point, it will replace us completely. But then who knows what > values will motivate it? It may just sit and live in Platonia. > > > >> >> I think you miss one possibility at the other extreme. Maybe there are >> aliens that are so big we don't notice them. There was a scifi story, I >> believe by the Strugatsky brothers, in which aliens visit Earth but they >> are vaporous thin structures of gases and stand many kilometers tall. They >> are almost completely transparent so they are not even noticed at first. >> And they never give any sign of noticing us despite attempts to get their >> attention. Eventually they just leave as mysteriously as they came. >> > > That sounds like a great story. I'll see if I can find it. Is it Roadside > Picnic? ( https://en.wikipedia.org/wiki/Roadside_Picnic ) It reminds me a > bit of this episode: https://www.youtube.com/watch?v=3oO3tUVLpIM > > > No. I think it was well before "Roadside Picnic" and it was short > story...only a few pages as I recall. But Stanislaw Lem has also written a > couple of stories about the radical impossibility of communicating with > aliens, simply because they are so alien. > > Brent > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. 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