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I’m Convinced We Found Evidence of Life on Mars in the 1970s (scientificamerican.com)
477 points by simulate 31 days ago | hide | past | web | favorite | 259 comments

What, no mention of ALH84001? I was mesmerized by the live TV press conference by a large group of NASA scientists back in 1996 of evidence of life on Mars from the analysis of a meteorite:

"Scientists headed by David McKay of the JohnsonSpaceCenter in Houston found that the rock, called ALH84001, had a peculiar chemical makeup. It contained a combination of minerals and carbon compounds that on Earth are created by microbes. It also had crystals of magnetic iron oxide, called magnetite, which some bacteria produce. Moreover, McKay presented to the crowd an electron microscope view of the rock showing chains of globules that bore a striking resemblance to chains that some bacteria form on Earth. “We believe that these are indeed microfossils from Mars”"[1]

I was disappointed that the story fizzled out. One microbiologist concluded that bacteria from Earth had "contaminated the Mars meteorite. Other scientists pointed out that nonliving processes on Mars also could have created the globules and magnetite clumps." But I don't think life is ruled out. This meteorite is hanging in as a "just maybe" like the Viking mission discovery.

[1] https://www.smithsonianmag.com/science-nature/life-on-mars-7...

I fear that the “it’s never aliens” credo was taken to the pathological case. Nothing can be life so why look for it? Nothing can be life, so any really complicated scenario not involving life must be true, always.

But they are looking for it. Science demands evidence for your claims. If x could be due to a, but also b, c, d, maybe e, you can't say x = a until you've proved that x ≠ b, c, d, e.

The fastest way isn’t to eliminate the other possibilities, it’s to find a unique test for a that can’t be met by any of the others. Bear in mind that your list of alternative causes may be very long and each require large amounts of work to eliminate.

I too find it strange that multiple landers have been sent to mars since Viking, ostensibly looking for evidence of present or past life, and have yet have carried no tests for it. I find the best way to find something is to look for it.

The authors suggest testing for chiraliry in an LR test. Life creates certain “handed” organic molecules while purely chemical reactions do not. They said there’s already designs for flight ready tests. NASA just needs to include it in a mars mission. But they have no plans to do so.

This significantly increased my frustration with NASA.

I thought life on earth favoring a particular chirality was supposed to be primarily because of like common ancestors and stuff. If you flipped the chiralities of everything, would stuff no longer work? Or, I guess really my question is, would it be nearly impossible for life on another planet to use the opposite chirality instead?

The test is not for right chirality, it's for any preferred chirality. Non-life is half and half at random.

Ah, cool, thanks

Life on our planet does. Doesn't mean that's the case everywhere else. Or even anywhere else, for that matter.

Conversely you can't say x != a until you've proven x = b or c, d, e. Which is GP's point if I understood correctly.

"However improbable", Sherlock Holmes is often brought up in cases like this...

That quote always rubs me the wrong way. To reach certainty through deduction you need a closed domain. Assume Holmes is 100% correct about the information he has, and he has three suspects, two of whom he ruled out. Does that mean the third did the deed? No. There may be information Holmes does not have and there is really no way for Holmes to know he does not have that information.

Holmes does appear to be operating under the closed-world assumption: https://en.wikipedia.org/wiki/Closed-world_assumption

That's contingent on eliminating the impossible.

the scope of which begs a complete understanding of the possible

In the "swapping spit" scenario, we the aliens and they are us.

If genetic material did travel in either direction, it would be easily verified.

There is life on Mars -- JPL just doesn't want to tell us. Follow this logic: 1) two planets in habitable zone - both spontaneously cause life; 2) then many or most habitable zone planets have life; 3) Of the trillions of stars in our galaxy, there must be multitudes that have hosted intelligent life; 4) we don't hear SETI signals; 5) that means SETI must have snuffed themselves out with some super-technology; 6) ergo, cannot tell the masses, because they will freak out knowing that we are all doomed, including all our offspring.

It seems quite implausible that JPL would have sufficient confidence that things would play out as you say (everyone freaks out because everyone is convinced by this line of reasoning) to deny themselves a rather good opportunity to get people excited about space exploration.

The biological plausible explanation is that there simply has not been enough time for other civilizations to form up. It took us 4 billion years to reach civilization from primordial goo. Apparently not many planets remain habitable that long. It does not matter if you have a trillion planets if they don't remain stable long enough.

In all the vastness of the universe, “we were the first” is a stupendously implausible hypothesis compared to “we were the only”.

If "we were the only" is true so is "we were the first" ...

However, there exists or has existed one planet with the first civilization ever.

it's not even entirely a given that we are the first, as it's unlikely any evidence of a small tribe of sentient dino villagers for example would persist to the present day.

Like a petal on the flower, or an apple on the tree, it's likely that planets fruit at about the same time.

Suggested reading: Rare Earth: Why Complex Life is Uncommon in the Universe by Peter D. Ward and Donald E. Brownlee. The basic premise is that complex life is incredibly rare, because only through a series of effectively chance events, did complex life happen on Earth.

Even if each of those events were actually inevitable, planet size, radiation received from host star, exact chemical makeup of atmosphere/oceans and any number of other variables could affect the time scale for a planet to fruit.

But on the universes timescale, a slight variance could still be thousands of years or more. So maybe there is life in some distant reaches of the universe, who are +/- a thousand years from our level of development. Their signals simply haven't reached us yet, or ours them.

And the odds that it’s us are astronomically even longer than the odds that I’m going to win the next Powerball, and I’m probably not even buying a ticket.

It is also stupendously implausible that our civilization arrives at all in a mere 14 billion years, considered against the gazillions of years in the potentially infinite lifespan of the Universe. Yet here we are.

If it is difficult for civilizations to develop, then our existence is so implausible already that being the first is not such a leap.

I did not imply at any point that we were the first, or only. Perhaps in our galaxy. I don't know if we could ever find out about civilizations in other galaxies.

There are a 100 billion galaxies. I'm ready to guess each has at least a few planets theoretically capable to sustain life for long enough.

We already know we’re all doomed. The sun bakes us in somewhere around 5 billion years.

Earth will become inhabitable faster than that. The timeline at


is thought provoking.

I think the scuttlebutt is the sun gets increasingly brighter and strips off all the earths hydrogen in about a billion years.

That’s more than enough time to colonize most of the galaxy.

Oh no my 401k retirement fund isn’t going to last that long

Here's what I think:

1. ET life formed and vanished so quickly that they didn't even get to the stage where they generate electromagnetic signals.

2. ET life formed and got to generate EM waves, but:

- they're either too far from us that we haven't detected those waves yet;

- they only recently got to this stage and the signals they produce have not reached us yet;

- or both.

3. ET life formed way sooner than we did; figured out how to generate EM waves, and then vanished entirely. So, any signals of their civilization they must have sent out there have already reached earth, but before we began listening for such signals.

4. Then again, since there are practically infinite number of planets with habitable conditions for ET life, statistically speaking, we must have already received a signal from at least one of them.

Which leads me to this:

5. ET life doesn't exist, because the universe as we know it is most probably a simulation inside a computer and the computational resources can only render so many different objects at a time. (This is serious stuff, researchers have already proposed methods for verifying this: https://www.washington.edu/news/2012/12/10/do-we-live-in-a-c...).

Earth level EM waves are indistinguishable from background noise pretty quickly thanks to the inverse square law. And we've been reducing emissions, not increasing them, as we shift to cell networks rather than one to many broadcast networks of old.

I wonder if Type 3 civilizations might engulf their star in a Dyson Sphere to block out light and make it harder to find. A dark forest where the life-bearing trees aren’t even visible.

The thing about that is all the energy from a star is still being radiated, just in infared. So if this was true a IR telescope should see a star like object with no visible light but a large amount of infared emitted.

Apparently Dyson spheres can be undetectable with IR telescopes:


People have looked. There are some candidates that have not been ruled out, but are not particularly promising. Do a Google Scholar Search for "IRAS dyson spheres" and you'll get oodles of papers describing attempts, new places we might look (I recall one suggesting they might all be surrounding the galaxy's central blackhole), current theoretical limits of our ability to search, new methods we might use to find them, etc.

> they will freak out knowing that we are all doomed, including all our offspring

Um, sorry to break it to you but the horse has left the barn in regards to future prospects.

Things may get pretty shitty for them, but if I could wager on such a thing, I'd wager on the species surviving.

who would you collect from if you wagered against, and how would you take it with you?

One could say we are already collecting from our offspring.

The wager is problematic for both sides. There's no end-point in which someone who was wagering for could collect.

It also depends on your definition of live.

The best broad test to look for life would be to look for an entropy source.

I think it's because when it is actually alien life the expectation is it will be obvious. If we are splitting hairs to find it we probably haven't found it yet.

Obvious? A colony of fungus setting up a new home on your own foot isn't even necessarily obvious—humans are constantly surprised by what turns out to be terrestrial life, so it's completely unreasonable to expect extraterrestrial life to be obvious when we see it.

the keyword here is expectation. that expectation may be misguided.

It looks like a lot of people think the presence of the oxidizer perchlorate is the cause of the false positive, but there isn't consensus yet.


On August 2008, the Phoenix lander detected perchlorate, a strong oxidizer when heated above 200 °C. This was initially thought to be the cause of a false positive LR result. However, results of experiments published in December 2010 propose that organic compounds "could have been present" in the soil analyzed by both Viking 1 and 2, since NASA's Phoenix lander in 2008 detected perchlorate, which can break down organic compounds. The study's authors found that perchlorate can destroy organics when heated and produce chloromethane and dichloromethane as byproduct, the identical chlorine compounds discovered by both Viking landers when they performed the same tests on Mars. Because perchlorate would have broken down any Martian organics, the question of whether or not Viking found organic compounds is still wide open, as alternative chemical and biological interpretations are possible.


In a paper published in December 2010, the scientists suggest that if organics were present, they would not have been detected because when the soil is heated to check for organics, perchlorate destroys them rapidly producing chloromethane and dichloromethane, which is what the Viking landers found. This team also notes that this is not a proof of life but it could make a difference in how scientists look for organic biosignatures in the future.


It's funny that perchlorate is likely what confounded the LR experiment, as the discovery of perchlorate in the soil made a lot of folks less optimistic about life being able to survive on the Martian surface.[1]

[0] https://en.wikipedia.org/wiki/Viking_lander_biological_exper...

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500590/

Yep, definitely ironic that an oxidant like perchlorate reduced the chance of finding life.

You’ve been a great audience, I’ll be here for the next 7 sols!

> Inexplicably, over the 43 years since Viking, none of NASA’s subsequent Mars landers has carried a life detection instrument to follow up on these exciting results

I'm very surprised by that.

Especially since, as the article says, "NASA maintains the search for alien life among its highest priorities".

I thought that would obviously translate to sending life-detection instruments to B̶a̶r̶s̶o̶o̶m̶ Mars.

This fact often catches people by surprise when I tell them also. The more conspiratorial theory is that JPL prefers not to include life detection equipment because it would mean the end of robotic missions and more of an emphasis to get humans there to do real biology, which is more the domain of Houston Mission Control. Follow the money...

Cmon folks, let’s be realistic. If someone at NASA had indeed reason to believe life exist(s/ed) on Mars it would 200% have leaked by now. No funding discussion would inhibit someone from leaking this information. It’s the biggest discovery in human history and you think someone’s sitting on it for funding reasons?! Especially since the immediate reaction would be to pour billions into them following up?

A big discovery has a high burden of proof and that’s basically where we’re at. There’s definitely reason not to rule it out but I can’t believe conclusive evidence is being sat on by all of NASA for funding reasons.

Let’s speculate for a sec. Tardigrades can survive space. Things have been hitting us knocking earth stuff into space for billions of years. Some of that stuff probably made it to Mars and back in the day it was pretty liveable. It’s not far fetched. None of that negates the above.

TFA was written by a NASA team member, and is literally saying "we did discover life on Mars". If that's not "leaking" then I don't know what is.

Yet here we are, discussing it as if this is fake news. I don't think we need to call this a "conspiracy", just the lack of official confirmation makes anyone saying that there's life on Mars sound like a crackpot.

What's TFA?

The Farking Article

I don't think that microscopical life in Mars is the biggest discovery in human history. It's more like an interesting trivia. But it doesn't change people's lives any more than the discovery of water on Mars.

It may not change people's lives directly (unless you're an astrobiologist), but it would absolutely change our lives indirectly-- the effects on the future of space exploration and the ongoing human conversation would be dramatic. Ultimately no one's mind is likely to be changed about much of import - such as religious beliefs - but at the very least it will mean we approach Mars missions differently.

It'd surely have impact in the related fields. However, I'd save the "biggest discovery" title to findings that debunk and completely change our assumptions, rather than more evidence for assumptions we already hold. Perhaps, having another life origin to study will lead us to new understandings. But the mere discovery of alien life is not that disruptive.

Given all theories and evidences we've observed thus far it's expected that we are not the only living things in the universe. Except for some fringe theorists, everyone expects life to exist in other places besides Earth. Finding out that life exists elsewhere in the solar system would just be more evidence for what we already belive to be true. So, not really huge news in itself.

Solid point, if you're academically inclined. For the majority of the world's population, though, it's hard not to think "ALIEN LIFE CONFIRMED" headlines in every major news outlet might lead to some other shifts in public opinion.

I think one of the biggest questions about our universe is whether life is unique to Earth. It's pretty silly and self centered to assume that we're unique, but we don't really have any real way to confirm or deny the question outside of the ability to find signs of life within our solar system. So yes, finding signs of life on Mars is basically answering one of the most fundamental questions about our existence.

But only sort of a biggest question. Once we know there’s life out there beyond us other questions arise. Perhaps the next big question would be is any of it intelligent and/or industrial like us?

nobody knowing there's actually aliens out there would ever leak anything if they're sure there's certain danger in doing it so. If they found something and nobody is saying anything, not leaking a word, there should be a really important reason for that.

This argument can be flipped, though. If life were found on Mars, that might lead to a ban on manned Mars missions, because there's absolutely no chance that a manned mission will not contaminate Mars with microbes from Earth. So to protect a Martian ecosystem, we might have to use only robots to explore Mars.

On a civilizational time scale, I just don't see the whole human race deciding that "ohh nooooo, the pwecious pwecious native microbes might be disturbed if we go there" holding up for very long. This is far, far from the opinion of the entire human race right now, despite how common it may seem on HN. At most it'll be a funny footnote that the school kids learn about in their orbiting space station schools where they'll laugh at what the funny old groundpounders thought, before the Earth became uninhabitable after the asteroid pounding given to it in the Great Space Indepedence War of 2343.

In evolutionary terms, it does not seem to be pro-survival attitude.

or rather to protect us from what is coming back; I remember that the Apollo astronauts were kept in quarantine due to that fear. I think it's sort of funny that the effort to make us a multi planetary species might as well doom us if we catch something unusual while on Mars.

Would extra terrestrial bacteria have any chance versus generation after generation of earth specific bacteria in life forms on earth? I mean, wouldn't it be like a baseball team showing up for cricket or maybe slalom?

Whatever bacteria might live on Mars had millennia of evolutionary pressure to adapt to an environment with no lifeforms larger than an inch. It seems very unlikely that they will interact with human physiology in a meaningful way.

That doesn't mean they can't be harmful though. Bacteria that quickly eats through concrete for example would be just as bad to bring back.

> It seems very unlikely that they will interact with human physiology in a meaningful way.

Human physiology depends very much on various bacteria. Supposedly, there are 10 times as many bacterial cells than human cells in our bodies. Perhaps you should reconsider your attitude if you take into account that bacteria from Mars might wreak havoc on these bacteria?

Maybe it would be like an adult soccer team showing up to a 4th grade basketball game.

Does anybody know either way?

It's quite unlikely that alien bacteria would be able to target humans.

the reverse side of this argument is that the human immune system may not be able to protect against alien bacteria.

I don't know that much about biology, but my understanding is that if the bacteria does not target our bodies, then it will be just some inert material that will eventually be eliminated by one mechanism or another.

the bacteria will be looking for food. either it finds it or it doesn't. if it finds it it will grow and reproduce. that in itself is not the end yet, as there are already many bacteria in our body that live in a symbiotic relationship. only if it reproduces to much and overwhelms our body somehow it becomes a problem.

but also, if it doesn't find food we are not safe yet. the bacteria itself could be toxic in some way and it could reproduce elsewhere and enter our body through food or other ways.

it doesn't need to target our bodies. it just needs to cause an averse reaction of some form.

compare to chemicals for example. they don't target anything. they are inert. yet some chemicals are poisonous.

Why would anyone care about Martian ecosystem?

Not my field, but I’ll hazard a guess: because once we contaminate it, we ruin our chance at getting an un-tarnished understanding of it?

We've already contaminated it

Uh, no, this is nuts. I work there and personally know the PI of the below-linked instrument which is designed to “search for organics and minerals that have been altered by watery environments and may be signs of past microbial life.” Some of the best engineers at JPL have worked to get this ready for Mars2020.


There is a standard and open pipeline to getting an instrument on these missions. Scientific American is not part of it. It’s more like AGU, LPSC, Icarus, and the National Academies decadal survey — writing actual instrument proposals with hypotheses and trace back to hardware that can make the measurements needed to test the hypothesis.

Which seems kinda silly to this layman because there are no shortage of potential robotic missions.

I don’t support the conspiracy theory, but the shortage isn’t potential robotic missions, it’s money for missions.

This assumes the amount of funding would remain the same. Would it? Hell, if they found life on Mars I'd consider switching jobs to work on that. I'd be surprised if tax-paying people wouldn't be open to funneling more tax-money towards space travel. Human- or robot missions, regardless.

It doesn’t assume a fixed amount of money. The total amount could grow and JPL could still see their cut shrink.

That would be some seriously short term thinking though.

If humans go to mars we will be proceeded by the robots.

well it's too late now to go to Mars without having been preceded by robots

True, but not exactly what I meant.

Constructor bots instead of explorer bots.

I would guess that all ships would rise and spending, public and private, would go up, if they ever got serious about a need to send humans to Mars

I doubt it. Finding life would be a real mindfuck for religious beliefs and has a real possibility of causing issues in society,

So what happens if we do discover life on Mars?

Popular sentiment would quickly swing (or be swung) towards leaving Mars alone. "We've f*d up one planet, let's not destroy two!", "leave Mars to the Martians", etc.

Vested interests opposed to the space program would get legislation passed that declared Mars indigenous life to be a protected species, and interference with a planetary ecosystem a criminal act.

That would be the end of any exploration or settlement.

But if they don't include life detectors, and declare that "no life has been detected there", then discovering that they were wrong will happen once the colony is already in place. Too late, the ecosystem is already altered, might as well keep going and study it.

Better to ask forgiveness than permission.

> Ghost-like moving lights, resembling will-O’-the-wisps on Earth that are formed by spontaneous ignition of methane, have been video-recorded on the Martian surface;

I was surprised by this statement. I thought atmosphere on Mars is too thin to support any kind of combustion.

After some searching the closest thing I found was a bunch of popular science articles seeing aliens in white pixels on images from Curiosity [1]. It seems all very much like people trying to make a thing out of image artifacts. NASA's much more reasonable explanation is stray reflections in the optics or cosmic particles striking the detector.

[1] https://www.cnet.com/news/nasa-mars-curiosity-rover-saw-a-we...

I get the feeling that contrary to rhetoric the search for life on Mars or anywhere else is almost an anti-priority. Not much designed to look for life has been sent since Viking in spite of direct observation of water ice, brine, and other features suggesting ideal landing sites for such experiments.

If perclorates were the cause of the Viking positive as many suggest, why not send a new experiment designed to rule that in or out? Why not send a whole lot more chemical tests for biology, or a microscope for that matter?

I suspect there is strong concern about the social effects of the revelation of any extraterrestrial life, even microbes. From what I see of the mass psychosis that is most of current political discourse this concern might not be unfounded.

I think it's the opposite. There are scientists who are obsessed with finding extraterrestrial life because of their philosophical views regarding man's place in the universe. The fact that our universe seems primed for life has bothered so many gung ho atheistic scientists that they've conjured all sorts of semi-pseudoscientific multiverse theories (Sean Carroll). That's one part of it. The second part it's reducing abiogenesis to a simple process that just "takes time" and is almost inevitable. The goal is to try to shove bare faced facts into a dusty drawer while you trot out the latest sensational theory. This is why there's been constant attacks on the Big Bang theory even though it's one of the triumphs of modern cosmological science. It all becomes so easy to justify when you define science as "what atheists believe."

Methodological naturalism as applied to the scientific Certainly has no dependence on atheism.

Who categorizes science as an intrinsically atheistic endeavor other than religious apologists?

The perception that all scientists are atheists comes from a small number of loud dogmatists. This is exactly like the perception that all Christians are literalist fundamentalists or hold right wing political beliefs.

All scientists are not atheists, just the smart ones. Depends on your interpretation of the word though. I don't consider atheism to be a complete abscence of philosophical pondering. I believe we haven't explored emergent consciousness enough and that makes it a mystery. But a scientist believing in a God from an ancient textbook is a red flag for me

Only 7% of Nobel Prize winners are "smart"? https://commons.m.wikimedia.org/wiki/File:Religion_of_Nobel_...

How would microbial life on mars be a confirmation of atheists beliefs?

The nature of general religious beliefs is that they're essentially non-falsifiable.

And particularly in this case, life on mars wouldn't be shocking due to the fact that there is life on earth and there is a small amount of mass transfer. If there isn't some amount of microbial life on mars it would only because of the dumb luck that there hasn't happened to be anything on earth that could get transferred, survive the transfer, and survive on mars.

Why would a position on athiesm have any negative bearing on whether the universe is teaming with life? Atheism would likely posit that finding life all over the place hints that it's a common natural process.

People could also see it as evidence for a creator, e.g. that the universe is obviously fine tuned for life. Theism isn't scientifically testable or falsifiable, so science can't say much of anything about it.

Moving the goalpost doesn't prove much. Going from how special we are vis a vis Adam and Eve, to accepting life is actually everywhere and has been since well before Earth was a thing is itself a huge leap to make.

Is it really different than any other retcon that's occurred in the last 500 years? At least in Christianity anything can be de-emphasized or treated as metaphor if it is inconvenient.


The priorities currently for Mars seem to be gathering correlated data to strengthen or weaken the case overall.


2x. Look at the test suites on everything we've sent since Viking. Viking gave us odd results so we've set out to do a good job proving things one way or the other.

I mean, you're probably right. If there was life found on Mars, there would be precedence to protect it - I could see this even stopping ANY manned missions (fear of contamination).

If the planet is dead, we as a civilization get the privilege to do whatever we want with it. Also a dead planet means the idea of the Monotheistic God kind of remains.

Ignorance is bliss.

Mars is getting contaminated in the near future, whether we find life on it or not. Whether we collectively want it to be or not. Given the ever-decreasing cost of launches into space, the increasing access to small satellites, I think suspect it's inevitable that some collection of Earth microbes will get a ride to Mars within the next century. Whether it's a motivated team of grad students, an obsessed billionaire, or a small nation that doesn't decontaminate its lander before launch, it's going to happen.

> Also a dead planet means the idea of the Monotheistic God kind of remains.

I don't follow why life on another planet would have any bearing on the idea of a Monotheistic God.

This is why I kind of admire the biblical myths; their selective details and smoky metaphors have proven incredibly resilient to new truths, and invite so much speculation.

The garden of eden could be in some far flung galaxy, from which we “life”, were expelled as microbes, thanks to the sins of relatives we wouldn’t recognize. The rib of Adam could symbolize the arbitrary evolution of sexual reproduction from asexual origins. The forbidden fruit could represent some inevitable nuclear holocaust spurred on by some intra-species conflict, which prompted life to be cast out and begin on another planet. Something unique about our shape of life means that we’re stuck in a cycle of destructive evolution that cannot be saved from itself, excepting for the divine intervention of some less imperfect shape of life.

Anyways, I’m rambling! I hope this sparks somebody’s theological-scifi bug and produces a mildly entertaining narrative in somebody else’s head. :)

It makes God's ultimate and unquestioning perfection in creating the Universe called essentially into question. If there is life on Mars, then it's no small leap to think there's life outside of the Solar System. What place then do we, as God's children have in the Universe, and in God's grand plan?

Stuff like that.

I often wonder why these are always auxiliary conversations. Ever since I was young, like most kids (I have 4), I also had this deep yearning for knowledge on life external to earth. Wonder why this never has gone mainstream.

I think that the desire is mainstream, just look at the TV shows and movies that explore the idea of alien life.

But I think the reason it’s not talked about more is that our knowledge is essentially non existent and hasn’t really changed in, say, the last fifty years?

Fifty years ago we didn't even know whether there were planets outside of our solar system.

But that hasn’t really changed our knowledge of alien life much. We still know it’s possible for it to be out there, but we have no idea if it is.

> But that hasn’t really changed our knowledge of alien life much. We still know it’s possible for it to be out there, but we have no idea if it is.

The Drake equation is a nice framework to determine the probability of life outside of our planet. Sure, the end result is still a big mystery, but many of the variables in the Drake equation have been solved or narrowed down (e.g., star formation, planet formation, etc.). To say that there has been no progress in the last 50 years is silly.

A large amount of our solar system hadn't been mapped yet (and wouldn't be for a few decades)

Let's assume for a moment that we did find something resembling simple organic life on Mars and confirmed that earth isn't the only life bearing planet. What functionally changes for our existential understanding of the universe? I'd argue little to nothing. We'd learn a bit more about organic life, but no fundamental philosophical or existential questions would be resolved. Life has been confirmed to be able to thrive in many more extreme places here on earth than anywhere observed on Mars. There wouldn't be any firm resolution on the question of whether humans are the only intelligent species in the universe.

I think that would be a different answer if we found inorganic life, as that would blow up the concept of organic life as singular in "life" bearing capability. I doubt we would recognize inorganic life as "life" in that case however, as humanity has a poor working definition of "life."

Absent a recognizably intelligent form of life found off planet, I doubt much would change (practically or existentially) for us here on earth.

> no fundamental philosophical or existential questions would be resolved

If you don't consider "does life exist on other planets?" to be a fundamental, existential question, can you share an example of what you do think is such a fundamental question?

Finding life on Mars wouldn't necessarily resolve any fundamental questions, but it would open up a whole new realm of questions. Is it similar to life on Earth? How similar? Is there evidence for or against some form of panspermia? (at its most extreme, life arriving on Earth from outside the solar system, but this could also be life arising on Earth and being transported to Mars via impact ejecta, or vice versa)

Also, lots of worthwhile science is done even though it doesn't have an immediate and obvious impact on everyday life. I can't think of any particular way in which the discovery of gravitational waves has changed my life, for example - but I recognize that the work that's gone into it has advanced human knowledge, and probably will indirectly benefit my life (or my descendants' lives) in ways I can't predict.


Is the concept of objective meaning valid in any possible universe?

Is it possible for the universe to be a fully observed deterministic system?

Is there a universal objective function motivating what we consider reality?

Is it possible to determine with certainty the origins of what we can conceptualize as reality?

Is it possible to forecast with mathematical certainty events in future time steps.

Basically just off the top of my head my questions boil down to: Can laplaces demon actually exist, is there a resolution to the munchausen trilemma and is godels incompleteness theorem disprovable.

> is godels incompleteness theorem disprovable

Do you actually understand its proof? On what basis would it be disproven? It's really difficult for me to even conceive of what disproving it would even "mean" - you seem to think that it's somehow tied to whether the universe is deterministic, but it's not. A "disproof" would essentially break the very logical tools used to construct itself (since it is the nature of these that Godel's theorem concerns); it's like trying to drive further north than the north pole - there simply isn't a conceptual direction to go unless you completely redefine the meaning of "north".

Edit: Also, Laplace's demon has likely been formally proven to be impossible: https://phys.org/news/2018-05-proof-reveals-fundamental-limi... Perhaps your apparent belief in Laplace's Demon combined with the comparison of this proof to Godel's Theorem is your motivation to suggest that it can be disproven?

I agree with you that any progress in these areas would include breaking pretty much everything we "know." That's kind of the point though, current epistemology and computability questions basically stop with these irreducable theories. So we live with this irreducable uncertainty currently.

I'm not proposing solutions or saying that there are errors with these proofs. Rather, when I finally understood them years ago it induced an existential crisis that I don't see any pathways to resolve.

My hypothesis is that humans aren't capable of conceptualizing experiments or building tools that could approach the three most intractable problems in epistemilogy. Maybe we don't have the math to do it, or it's fundamentally intractable and it will never be resolved, I dunno. But those are much more interesting questions than "is there an amoeba on europa?"

I think you'd probably be interested in Gerard 't Hooft's latest work: https://arxiv.org/abs/1405.1548 It's rather, shall we say, controversial (that is: widely rejected by his peers), but it's an attempt to construct a framework through which the laws of the universe can be interpreted as deterministic which leverages the sorts of epistemological concepts you seem to be interested in.

(That being said: I personally find "is there an amoeba on Europa?" to be supremely interesting, but to each their own.)

Thanks for this, I'll definitely take a look. My concern always, as you point out, is falling into crackpottery territory. Hopefully being acutely aware of that serves as an inoculation to some degree.

I should also state, I certainly find the concept of life on other planets extremely fascinating. However as I said above its insufficient to give clarity to some of the more fundamentally existential questions around our existence.

I should also mention - there is quite a bit of discussion on 't Hooft's work on StackOverflow, including heavy participation by 't Hooft himself. I don't have any pointers handy, but they should be fairly easy to discover with a minimal amount of searching.

I don’t accept non-constructive proofs that require “constructions” as being valid. (Diagonalization is another invalid technique in my book.)

So there’s at least one of us.

Wow, you're really smart! I'm glad you're here to discuss things with us.

That being said, for most people who aren't operating on your level, the fundamental existential questions haven't changed much in a few hundred years. "Are we alone in the universe?" is probably among the newest for us.

I'm assuming you're being sarcastic. If so it's unfortunate that just answering honestly warrants such hostility.

To say what I think JasonFruit is trying to say, but with less condescension:

Your questions are valid and really interesting, but that doesn't make the questions of "Do other planets have life?" and "Where did life on Earth originate?" invalid or uninteresting. Personally I'm interested in all of them.

Do other planets have life? Is a ridiculous question to ask, it is epistemologically one of the weakest hypothesis possible given the scale of the universe and the non singularity of what make earth the earth.

Well sure, I take your point. We live, we die. Science tells us how it all happens, but can never tell us why it happens at all.

And yet despite the certainty of death, we, individually and as a group, seem to have an unquenchable desire to know more. To know is to grow, and this collection of processes we call life has never been seen off the planet so yeah, it'd be quite some growth.

If the life evolved independently of life on earth (ie, no panspermia or anything like that), then it would have philosophical/existential implications because of the Great Filter Hypothesis - https://en.wikipedia.org/wiki/Great_Filter.

Edit for a TL;DR - The basic idea is that, if we don't see evidence of intelligent life in the universe, it must be because star traveling species must be rare. If we find life evolving twice in one solar system, then the early parts of life evolving must be relatively easy - which suggests the later parts of life becoming technologically advanced are the hard parts. In other words, life on Mars may mean that there may be more problems ahead of us than behind us.

If it were organic, we would not know if that life evolved independently from life on earth though. So, again finding non-intelligent organic life elsewhere doesn't answer the question of where did we come from.

Simply verifying distance between two similar things isn't a sufficient variable to answer questions about distinctiveness of origin.

Not necessarily. It just suggests the bottleneck for life lies at whatever point is after mars. Nothing would suggest that complex life gets progressively more difficult to evolve.

Right now there are a few places for the great filter. To my knowledge:

1. Life

2. Multicellular life

3. Intelligent life

4. Interstellar colonization tech

If you make it through all levels you should be colonizing the galaxy and detectable by us therefore.

Finding life with a separate origin than ours removes one of the possible spots for the great filter and makes it significantly more likely that the great filter is ahead of us rather than behind.

This is a question that will help with the survival of humanity.

> What functionally changes for our existential understanding of the universe? I'd argue little to nothing.

It depends on how different it is chemically form earth life. If it is similar enough that it shares a common origin, it's no big deal. If it isn't, then that's a massive deal because it means life originated twice in one solar system, therefore is probably widespread.

Whats the common origin of organic life again?

That it originated on one planet and was sent to the other by ejecta, as mentioned in the article.

That's a hypothesis... It's still totally speculative

Presuming SpaceX pull off their plans, there will be trips to and from Mars. We'd better be pretty sure what microbes we're being exposed to or bringing back to Earth before we do.

Or we might get a repeat of when the Spanish brought disease to the Inca and Maya.

The mere knowledge of life is viable off-Earth is huge. If we find it on our nearest neighbour, the chances of encountering it elsewhere rise markedly. Hopefully it would trigger a search elsewhere in the solar system, like Europa.

>> Or we might get a repeat of when the Spanish brought disease to the Inca and Maya.

Unlikely. There's been no animal hosts on Mars, in which such a micro-organism might have evolved to threaten humans on Earth.

Not to say we shouldn't be careful for other reasons though. The bigger risk is the sudden extinction of entirely different branches of life, by more highly-evolved Earth-originating species.

I think the other person is saying that Earth bacteria could potentially wipe out Martian bacteria if the conditions are right. And that would be tragic.

That was exactly my thought. We discover extraterrestrial life, and inadvertently wipe it out, or just swamp them with an invasive species, without getting a chance to study them before we mucked up their ecosystem. As you say it would be tragic, but also very typically human.

I'd argue that the jump from 0 to 1 of "knowledge of life on other planets" would be huge. Currently, we have an almost pseudo-religious understanding of what place life holds in the universe, but that's based on the fact that when we've looked up at the cosmos for all of history, it seemed impossibly devoid of anything familiar. The discovery of life on another planet (even if that life somehow originated on Earth), turns the proposition of finding intelligent life elsewhere from at best a 50/50 question of belief into a near certainty. And that is huge.

>we've looked up at the cosmos for all of history, it seemed impossibly devoid of anything

This is popularly misunderstood. We obviously don't see Type 3 civilizations, but if another of our own civilization was in our galaxy, we would have had an very small to extremely small chance of seeing it.

I'd wager life is everywhere, and just as is the case on earth, it pays, in terms of survival, to blend in with your surroundings.

Disagree- folks outside of the sci-fi bubble won't appreciate microbes on other planets. 0 to 1 happens when we find multicellular organisms with cognitive capabilities IMO

"Folks outside of the sci-fi bubble" rarely appdeciate much about non-monetary impacts of space. But discovering life - even alien life - would really shake up many big religions, which tend to assume we're special, unique creations. I'm sure religions would eventually evolve to accomodate the discovery in their belief systems, but it would get noticed by regular Joes and Janes.

Those come later, in the form of evolution. If we find the precursors alone, novel forms of single cell life still at that early stage, we can learn a whole lot about how multi-cellular life came about.

Doesn't really matter.

> What functionally changes for our existential understanding of the universe?

The anthropic principal becomes less compelling; to say nothing of the religious implications.

Religion will have absolutely no problem to adapt to new information and incorporate it as though it had always been there. This has happened time and again in the past to the point where the religions of old would have been in direct contradiction with even the most basic scientific knowledge if they didn't adapt. The funny thing is that the so-called holy books are full of stuff that no sane human would believe in. That doesn't stop a lot of people from doing just that when those books are creatively re-interpreted by intermediaries.

Religion will last for a very long time into the future, forget about major lasting change on that front other than some rearguard action to ensure survival.

I did not intend to state the implications are the end of religion; simply that many faithful will alter their faith, in no small manner.

I highly doubt that. If the genetics, the silicon revolution, access to space imagery, quality education, the internet and science in general did not alter faith in a drastic way I don't think 'life on Mars' is going to do anything either unless it comes in the form of little green creatures.

Yup. It's like how many religious people differentiate between "evolution" and "microevolution," with the latter (basically) encompassing whatever evolution happens to have been experimentally witnessed, no matter how drastic. Generally anything involving bacteria gets lumped into this latter category.

Curious that you don't recognize a significant shift in religious thought in the last century.

What shift would that be?

Until the 1970's or so it was getting better, since then it's gotten worse if anything.

On the Christian side we have whole continents that are following some cliff notes' version of Christianity, mostly centered around money and some opportunistic politics. On the Islamic side a small group of fanatics has managed to divide the world in a way that seemed unthinkable 25 years ago and so on.

Nah... religious people don't depend on reason, logic, evidence, etc. They can (and will) always absorb any new discovery and incorporate it into their belief systems in such a way that it doesn't invalidate anything they already believe.

Some people think Christians would have a hard time with extra-Terran life because the Bible doesn't mention any life other than the life here, and therefore any such life would arguably be free from the weight of Original Sin, yada yada yada. But I'm pretty sure if life on another planet was discovered (even intelligent life) they would just reinterpret the Biblical references that seem to refer to "Earth" as referring to "The Universe" and make "The Garden of Eden" a metaphor, and the flaming sword would become a supernova, blah, etc., yada, blah, blah, blah. At the end of the day, approximately 0.0% of Christians would say "Hmm... the Bible is obviously incomplete and or inaccurate, so maybe the whole thing is a load of bollocks" or whatever. And I expect it would be about the same for every other faith.

No, because the origin of life on Mars would probably be the same event as on Earth, with life having been transferred by impact ejecta. It would not allow us to conclude that origin of life was common.

Perhaps, or perhaps it's different enough that it most likely developed independently.

In which case, why haven't we seen it already on Earth? Life will have been transferred back and forth between Earth and Mars for billions of years.

I read your whole post and all I can come up with is that if we found life of any sort on another planet it would completely change my internal narrative and I guarantee I'm not the only one. This would in a subtle or unsubtle way gradually influence literally most of the decisions we make on earth.

> Life of any sort

Aside from the narrow one involving the oxidization of carbon, I have a hard time coming up with a definition of life that doesn’t consider storms, planets, or star systems “alive”. In particular, they are all time-limited phenomena that are organized but somewhat unpredictable at macro scale and chaotic at micro scale.

Most of them aren’t self-replicating.

I think it's a shame that you're being downvoted for nothing more than expressing a reasonable, albeit apparently unpopular, opinion.

For plenty of us, AndrewKemendo is right... learning that there is life on Mars would not answer any particularly fundamental questions. Maybe because a lot of people simply take it as a given that life exists on other planets (whether or not Mars is one of them isn't really a big issue) because they don't have the hubris to believe that there's anything so special about Earth as to believe that life could only emerge here.

Frankly, you can count me in that crowd. I'd be more surprised if it was somehow proven that there isn't life anywhere else.

To me, "fundamental questions" would be more like:

1. Is free will possible? If so, how?

2. How did the universe begin? If there was a "Big Bang" as popularly described, where did all the matter come from that expanded out of the initial singularity? If time did not exist before the universe began, how did the transition from state "no universe" to state "universe" happen, since - presumably - nothing can "happen" without time.

3. What is time?

4. Is space discrete or continuous?

5. Is time discrete or continuous?

6. Are there multiple dimensions of time, analogous to the multiple dimensions of space we know about?

7. Is our "4-D" world actually embedded in a higher-dimensional reality of some sort that we can't access/understand/see/etc.?

8. Is our world a simulation (ala The Matrix)?

9. How, exactly, do fields (electromagnetic field / higgs field / etc) permeate all of space and permit the existence of particles like photons or the higgs boson?

10. Is there actually a way to unify gravity and quantum mechanics?

11. What is dark matter? Where did it come from?

12. How will the universe end? Big crunch? Big freeze? Big bounce? The simulation ends and we all just disappear? Other?

13. Why is there any matter at all in the universe? The fact that there is implies a certain fundamental asymmetry to the universe, since if matter and anti-matter were created in equal amounts at the beginning, they should have annihilated each other leaving no matter behind.

14. Why are right-handed people more common than left-handed people?

15. Why does the universe itself appear to have a "handedness" property[1]?

[1]: https://arxiv.org/pdf/0812.3437.pdf

In fact these are the lines of questioning I'm most interested in and nearly none are resolved by the existence of other intellingent life, that is unless they are more intelligent.

I feel like this should be more pervasively held belief to a bunch of people with a higher than average propensity of consuming scifi. Star Trek did a pretty thorough job of showing that the same fundamental questions persist even if we assume there exist more intelligent species out there.

But what would be the geopolitical effects of having found the ruins of an old datacenter, under the dust of a couple of millions of years, old hardware, looking like maybe 500 years more advanced than the state of the art on Earth.

You would know there's tech out there, the first able to reach to it will have the edge over the rest for centuries ahead.

The effects will be massive, no one dolar, yuan, yen, gold bar would be left unspent in the quest to get there and learn before the others.

what? so would we have a common ancestor with this organic life (like all life on earth shares)? id think that has philosophical and existential implications

The barrier to be interested in these things is far lower than it is to directly work on them.

Then there's the realities of being an american adult where even science is politicized. Think of all the boomers that grew up watching the space race with baited breath. I bet some of these same people today would support a politician who would defund NASA if it meant saving $30 a year on their taxes.

> baited breath

Bated, as in abated.

Fun fact: bated breath was coined by Shakespeare.

It might be too mainstream. As in, anyone who believes in extra terrestrial life is probably an enthusiast. "Real scientists" are sceptical.

Thus many scientists try hard to dismiss evidence of alien life, because that is fashionable. Or at least, the alternative is very kitschy.

I'm certain that the vast majority of scientists, physicists for certain, do "believe" in extraterrestrial life. Belief makes it sound kind of quirky though. It's essentially a probability measurement. Is it more likely that we are the only life in the universe, or not? You reach the same conclusion whether by intuition or by what crude modeling we're capable of. It's not really possible to create a compelling scientific argument for the lack of alien life. This is why the Fermi Paradox is a thing.

The reason people try to discount aliens is because you can attribute literally anything to aliens. And so you reach another equally simplistic binary. You discover some unknown phenomena. It is aliens, or not? Well we've discovered a whole lot of unknown phenomena throughout the years (and centuries and millennia depending on how you want to play this game) and often times it really did look a whole lot like aliens, but to date it's never yet turned out to be them.

And since the determination of an unknown phenomena often comes down to probabilities, aliens get weighted down a good deal. But nonetheless, I have no doubt that at least lurking in the back of every physicist's mind is that something now as regular as a fast radio burst could indeed finally be those LGM - the kind of joking nickname given to the first radio pulsar discovery. Standing, of course, for little green men. Is it? Well probably not, but it'll always be probably not - including when it finally is.

You had the desire. What job do you do though? Almost everyone on earth has the desire. But it doesn't translate to everyone contributing money or their life work to doing so.

Extraordinary claims need extraordinary data. We don't have this data. https://en.wikipedia.org/wiki/Viking_lander_biological_exper...

It is "inconclusive" at best.

Generally I think people tend to underestimate how quickly life arose on Earth but underestimate how quickly it took for life to turn into complex life. Just judging from how things went on Earth we should expect cemosynthetic life to be relatively common but photosynthesis to rarely arise, much less eukaryotic cells or multi-cellular animals. I drew out a timeline comparing how long it took various stages of life to arise on Earth versus how long it took Mars to lose all its surface water. Even on Earth we humans didn't arise until relatively close to when the expanding Sun will render the surface uninhabitable.


> Surface water sufficient to sustain microorganisms was found on Mars by Viking, Pathfinder, Phoenix and Curiosity;

Ultraviolet (UV) activation of the Martian surface material did not, as initially proposed, cause the LR reaction: a sample taken from under a UV-shielding rock was as LR-active as surface samples;

Complex organics, have been reported on Mars by Curiosity’s scientists, possibly including kerogen, which could be of biological origin;

Phoenix and Curiosity found evidence that the ancient Martian environment may have been habitable. The excess of carbon-13 over carbon-12 in the Martian atmosphere is indicative of biological activity, which prefers ingesting the latter;

The Martian atmosphere is in disequilibrium: its CO2 should long ago have been converted to CO by the sun’s UV light; thus the CO2 is being regenerated, possibly by microorganisms as on Earth;

Terrestrial microorganisms have survived in outer space outside the ISS;

Ejecta containing viable microbes have likely been arriving on Mars from Earth;

Methane has been measured in the Martian atmosphere;

microbial methanogens could be the source;

The rapid disappearance of methane from the Martian atmosphere requires a sink, possibly supplied by methanotrophs that could co-exist with methanogens on the Martian surface;

Ghost-like moving lights, resembling will-O’-the-wisps on Earth that are formed by spontaneous ignition of methane, have been video-recorded on the Martian surface;

Formaldehyde and ammonia, each possibly indicative of biology, are claimed to be in the Martian atmosphere;

An independent complexity analysis of the positive LR signal identified it as biological;

Six-channel spectral analyses by Viking’s imaging system found terrestrial lichen and green patches on Mars rocks to have the identical color, saturation, hue and intensity;

A wormlike feature was in an image taken by Curiosity;

Large structures resembling terrestrial stromatolites (formed by microorganisms) were found by Curiosity;

a statistical analysis of their complex features showed less than a 0.04 percent probability that the similarity was caused by chance alone;

No factor inimical to life has been found on Mars.

“Sure, but where's the evidence?”

That is the evidence. Science is often done indirectly. We know that the Sun is made up of hydrogen gas but no one has been there. We know black holes exist, and that the big bang took place 15 billion years ago, that atoms are made up of protons, electrons and neutrons, and that gravitational waves ripple through spacetime. No one has directly seen these things, but we know them to be true based on indirect evidence.

Similarly, the above list of facts is indirect evidence for life on Mars.

The person who replied to you was actually making fun on people who claim there is no evidence.


This could all be explained by a weather balloon being dragged to Mars and releasing swamp gas

The author is not claiming that he knows for sure. Based on his involvement in the project, he has strong reasons to believe it. He is calling for more research in this area. It's similar to NASA's claim that life on Mars is likely to be found by 2021.

The author of the article has, quite literally, seen all of the relevant data we have on this. Yes, I am making an argument appealing to authority.

those “worms” if real, seem pretty convincing though [1]

[1] http://www.leonarddavid.com/curiosity-mars-rover-investigate...

Whatever the evidence, a major factor in this man's belief is likely to be the emotional attachment to the idea.

It's his life's crowning achievement as the project leader, and seeing indicators that turned out to be nothing must be a tough thing to come to terms with.

Excuse the cliche question, but what is Life?

If we make an AI whose thoughts and communication are practically indistinguishable from humans, and it controls a bunch of things that affect the physical world, is it alive?

If there's a disembodied mind somewhere that can think and imagine but never communicate or interact with anything, is it dead?

What about a human in a coma or permanent dreaming state? What about when they later wake up?

Okay nevermind thoughts and communication; What if there's an armada of "dumb" robots, spawned from a single factory, that can't think, only acts according to preset instructions, but still goes on to affect many things for hundreds of years, what should they be classified as? Would they be considered "artificial" life or automatons even if they existed for thousands of years and their creators were no longer around?

I don't think there is any single absolute criteria to classify all possible entities that must be out there or could theoretically exist, but the answer to "What is life?" is probably this:

Whatever other life thinks is life.

Life is that which is subject to Darwinian evolution.

That definition catches every single thing you'd call life, excludes all the things that clearly aren't, disambiguates some grey cases, and illuminates one or two new phenomena to be life which you might not have realized.

To be clear, Darwinian evolution means:

- It makes copies of itself (reproduction)

- The copies take traits from the original (inheritance)

- The traits can vary among the copies and between generations (mutation)

- The copies' ability to make more copies depends on the traits they inherit (selection)

> It makes copies of itself (reproduction) ...

Again, what about species that don't reproduce themselves, but spawn from a single "factory"?

That factory may be nothing like them. It could be a mechanical factory producing automatons (with human-level thought if you need that criteria), or a universally-unique "mother" creature, or even a non-sentient spawning pool where they spontaneously form every now and then.

If there are entire planets populated by such entities, and they have governed over many things for as much time as we have occupied our Earth, would you still classify them as not-life in your dealings with them?

That would be like not considering Taiwan a country. (Sorry, couldn't resist injecting contemporary political commentary.)

> or a single "mother" creature

How did the "mother" creature come to be? By what mechanism did its complexity emerge?

There is no known or plausible mechanism by which complex life can arise without evolution, and technology which does not change its design is (very appropriately) by the definition above, not life.

> How did the "mother" creature come to be?

It could be a human "mad scientist" creating hordes of Pikachus.

Suppose the scientist has also attained biological immortality for himself, and the Pikachus have spread to multiple planets over thousands of years.

You come upon such a colony planet, but you have no knowledge of their creator. They display no clues that hint at the scientist's role in their civilization (for a civilization it has become by now.)

You cannot discern how the Pikachus are coming into existence. Would you classify them as life? Why not?

How would your interactions with them and their interactions with the universe be fundamentally different than any other life you encounter?

What if they were robotic instead of flesh-and-fur?

I assume by "spreading" you mean that the Pikachus can reproduce?

Can they mutate? If so, then they satisfy all four boxes and they count as life.

If the Pikachus are made of cells, they'll certainly mutate/vary, since their heritable material is DNA, which is quite fragile.

Really, it's hard to imagine having "reproduction" without "mutation" in the imperfect physical world where errors are possible— I can't imagine any copying process, even a technological one, which succeeds with perfect fidelity and 100% probability. So if you have #1, #3 is basically going to be a given, because the universe is imperfect.

I don't think "what material they're made of" matters much, except that by definition flesh has to be alive, since it's made of things (cells) that tick all four boxes.

If the Pikachus don't reproduce themselves, and/or are created with perfect fidelity every time, then yes, I would call them technology and not life. We certainly wouldn't say that iPads (Pikachus) coming from a factory ("mother creature") are alive.

> I assume by "spreading" you mean that the Pikachus can reproduce?

No, they're all created by the mad scientist but can think, reason, communicate, teach, interact, invent and construct perfectly fine on their own.

> I don't think "what material they're made of" matters much ... If the Pikachus don't reproduce themselves, and/or are created with perfect fidelity every time, then yes, I would call them technology and not life.

So, to distill your criteria for life, it comes down to:

• Species must consist of "individuals" who join in pairs to produce another individual.

• New individuals must be slightly different from the individuals who reproduced them.

In other comment [0] you say that you could consider software to be alive:

> Note that "alive" by the given definition doesn't imply "conscious" or "intelligent"

> We certainly wouldn't say that iPads (Pikachus) coming from a factory ("mother creature") are alive.

But if an iPad had a software process that connected to another iPad, and they both commanded the factory to create a new, slightly different iPad, would they be considered alive? :)

[0] https://news.ycombinator.com/item?id=21231043

> Species must consist of "individuals" who join in pairs

Where did you get pairs from? If the Pikachus reproduced by binary fission (splitting in half and then growing a new half, like cells do), or had 18 genders, they would still evolve. They only have to make copies. Doesn't matter how.

> No, they're all created by the mad scientist but can think, reason, communicate, teach, interact, invent

If they can't reproduce (and/or aren't made of stuff that can reproduce), I would say complexity of behavior is irrelevant.

For example, the identical iPads coming off the factory line are still technology, whether they are loaded with simple software or complex software. The complexity could go all the way up to AI, but they would still be technology.

Note that we are used to "intelligent" meaning "alive", because the only intelligent thing we know of at this point in history (us) is alive. But I think it is perfectly valid to suppose that non-living things could be intelligent or even conscious.

> So if an iPad [...] created a new, slightly different iPad, would they be considered alive?

Yes, under those conditions they would certainly start evolving, and I think that's a perfectly reasonable line to draw between technology and life. In this new example, the "phenotype" of the iPads would change in a self-sustaining way, emergently, independent of any design or intent.

Alright: An individual of an species has to initiate the production of another individual of that species, and the new individual must have some differences from the preceding individual.

Do I have it correct?

Yes, but it's not everything. You've got two and a half of the original four criteria there:

> An individual of an species has to initiate the production of another individual

️^ reproduction

> of the same species

It depends on what you're defining to be "the same species", but if we take that to mean "shares traits with the original", then that's "inheritance".

> new individual must have some differences

^️ mutation

The one you're missing is "selection"— that the future success at copying depends on the traits you inherited.

If you have variable traits, but they don't at least indirectly result in either more or fewer copies, then there is no cause for some traits to become more prevalent than others in the population and evolution won't occur. You'll just get a jumble of random traits without any trend toward fitness (aka more efficient copying).

It is a fact of nature/mathematics that those four rules are necessary and sufficient for evolution to occur. If you set them up, evolution will happen, guaranteed. Those rules constitute an algorithm, carried out by the laws of nature on the substrate of physical matter, whose result is evolution— a trend toward increasing reproductive fitness.

Certain genetic algorithms could fulfill this criteria.

Could software be alive?

I'd say yes.

Note that "alive" by the given definition doesn't imply "conscious" or "intelligent" (though that is certainly logically possible for software too, though I doubt that has happened yet).

Excuse the cliche question, but who is Razengan?

If we make an HN account whose thoughts and communication are practically indistinguishable from Razengan's, and it makes similar comments in all the same threads, is this account actually Razengan's?

The answer to "Who is Razengan?" is probably this: Whoever other HN users think Razengan is.

The concept of life is not unique in this regard. One can form a similar argument for any concept whatsoever.

It's more useful to situate concepts such as 'life' at the center of constellations of other concepts such as 'self-determination', 'will', 'evolution', and so on.

I'm guessing they're using the scientific definition:

"A distinctive characteristic of a living organism from dead organism or non-living thing, as specifically distinguished by the capacity to grow, metabolize, respond (to stimuli), adapt, and reproduce"

- https://www.biology-online.org/dictionary/Life

Yes, I'm saying that definition may very likely be challenged once we actually start discovering extraterrestrial entities.

Going from the 'swapping spit' hypothesis. We can just say it suffices for there to be cells that divide and grow and contain DNA or RNA

> On July 30, 1976, the LR returned its initial results from Mars. Amazingly, they were positive. As the experiment progressed, a total of four positive results, supported by five varied controls, streamed down from the twin Viking spacecraft landed some 4,000 miles apart. The data curves signaled the detection of microbial respiration on the Red Planet. The curves from Mars were similar to those produced by LR tests of soils on Earth. It seemed we had answered that ultimate question.

This article does a poor job of explaining the experiment in question: "Labeled Release" (LR).

According to Wikipedia:

> ... In the LR experiment, a sample of Martian soil was inoculated with a drop of very dilute aqueous nutrient solution. The nutrients (7 molecules that were Miller-Urey products) were tagged with radioactive 14C. The air above the soil was monitored for the evolution of radioactive 14CO2 gas as evidence that microorganisms in the soil had metabolized one or more of the nutrients. Such a result was to be followed with the control part of the experiment as described for the PR below. The result was quite a surprise, considering the negative results of the first two tests, with a steady stream of radioactive gases being given off by the soil immediately following the first injection. The experiment was done by both Viking probes, the first using a sample from the surface exposed to sunlight and the second probe taking the sample from underneath a rock; both initial injections came back positive.[1] Subsequent injections a week later did not, however, elicit the same reaction, and according to a 1976 paper by Levin [author of the linked article] and Patricia Ann Straat the results were inconclusive.[12][13] In 1997, Levin, Straat and Barry DiGregorio co-authored a book on the issue, titled Mars: The Living Planet.


To recap, martian soil was incubated with small organic molecules bearing a radioactive label. A chemical process that converted them into CO2 would give off some radioactive gas. The gas was detected by both landers the first time the experiment was run, but not the second time.

It should be kept in mind that non-biological processes can also convert small organic molecules into CO2. Simple combustion will do this, for example.

This possibility is discussed later in the Wikipedia article (but not in the linked article):

> Despite the positive result from the Labeled Release experiment, a general assessment is that the results seen in the four experiments are best explained by oxidative chemical reactions with the Martian soil. One of the current conclusions is that the Martian soil, being continuously exposed to UV light from the Sun (Mars has no protective ozone layer), has built up a thin layer of a very strong oxidant. A sufficiently strong oxidizing molecule would react with the added water to produce oxygen and hydrogen, and with the nutrients to produce carbon dioxide (CO2).

However, this does not explain the discrepancy between the first and second test. And it leaves open the question of why both landers' experiments gave the same odd result (first test positive, second test negative).

The small organic molecules used as nutrients were those produced in a famous lab simulation of early earth. Its results showed that many of the basic building blocks of life could be formed by passing an electrical current through gases thought to be present in the early Earth atmosphere.

It seems like one could replicate this experiment on earth and verify non-biological origins for the observed results. I'm pretty sure we're familiar with the composition of martian soil by now. Create a sample with similar composition, blast it with UV rays in an atmosphere similar to Mars, and subject the soil sample to the same test.

Why isn't just a plain old microscope used to detect microbial life?

I'm guessing this could be a potentially much faster method to search the space, if there were not too many organisms up there? If you used a robot to prepare microscope slides of random soil samples, it could take an exceedingly long time to get lucky enough to find one, even if there are a lot around.

I'm not talking about detecting life. I'm talking about replicating the experiment which was performed on Mars to see if perchlorates are formed and some other reaction is responsible for the gaseous carbon isotopes.

I was curious how they automated all the testing and data sending back then. In Wikipedia it mentions that the Viking landers had 24 bit CPUs with 18K of plated-wire memory and 1280 megabits of tape storage. That's actually not bad!

Think about what you could do with an Apple II (8-bit CPU, 4/8/16k memory), and the Vikings were much more powerful. They were also the size of a Volkswagon, but I'm not sure how much was equipment vs computer.

A software update killed one of the landers by accidentally overwriting the antenna software. (40 years later, not much has changed...)

More info:


I wonder if there is an incentive to NOT find life there because of what that discovery might do to slow industrialization and colonization plans. Do we need to conserve that life? Do we need to set up preserves that are off limits to development? Opens a big can of worms (or bacteria) that I imagine some would rather see kept closed

realistically mars is way more interesting if its more than a boring rock

Even with microbes it would be a boring rock.

Anybody who thinks they want to move there should camp in Antactica for ten years, first.

And because people settled in Antartica it's no longer the miserable experience it used to be. These are pioneers, they do things that are had, they pave the way for the rest of humanity.

There is no migration to Antarctica. Nothing done by people there makes it any easier for somebody who wants to move there, because if your application for research is rejected, you stay out or set up somewhere far away.

It's far from boring. A planet closest in environment to us is interesting as heck for obvious reasons.

But if the CLR comes back positive, doesn’t that still mean there’s room for “it could be some unknown nonbiological process”. Wouldn’t saying with certainty that there is life on mars need somerthing like a microscopic image of cells dividing?

Here's the deal. There seems to be a default mode of behavior where people automatically reject news that conflicts with the status quo. In this case, these people are senior scientists not involved in the original mission. It's very unfair. Breakthroughs in knowledge could be happening right beneath our noses and people (not involved in the project), are actively surpressing or invoking pretzel logic to belittle the findings.

It seems like finding life on another planet is held to secrecy, but in my mind wouldn't a country want to take credit for finding the first signs of life outside of Earth? And therefore, if a country was to find and confirm life of another planet wouldn't they report it immediately?

I'd be flatly amazed if impact ejecta never carried any microorganisms from earth to Mars.

>Our nation has now committed to sending astronauts to Mars. Any life there might threaten them, and us upon their return. Thus, the issue of life on Mars is now front and center.

I'm pretty sure this is the whole point of the article.

Science is not about finding life per-se, it's about satisfying curiosity. Articles like these conflate real science (satisfying human curiosity) with finding life on other planets (we're not alone). Of course, finding life on another planet would be an amazing discovery, but for any true believer in science, it would just be the beginning of a million more questions, not the end goal.

While Scientific discovery would never stop, a milestone like this would be significant. And it would warrant awe.

Lots of conspiracy theories here.

Planetary Protection is already a thing, even though we haven't found anything yet.

"microbial respiration on the Red Planet"

I want to believe.

IDK, what would be the motive to hide that?

I don't think Levin is making the claim that NASA knows that there is life on Mars and that there is a conspiracy to cover it up. They both are looking at the same results and (honestly) coming to different conclusions.

Part of this is that it's expensive to do experiments on Mars, and space is limited. Each experiment you choose to do excludes you from doing others, so NASA has evaluated the evidence and doesn't think its the most efficient thing to pursue right now. Levin is trying to convince folks that the evidence is sufficient to warrant pursuing further experiments that would clarify what is going on here.

Less robotic missions, less money for JPL. More maned missions, more money for Houston Mission Control. I remember reading an article long ago about how none of the robotic missions to Mars can actually detect life and how strange and contrary to the rhetoric that fact is. When you look at it in terms of funding, it all makes sense.

To hide the lizard peoples secret base

Please stop posting unsubstantive comments here.

Not that I think there's a conspiracy, I don't think one has to try very hard to imagine reasons why the powers that be would suppress such discoveries.

Consider for instance how many US citizens are still religious today, and largely govern their lives according to religious beliefs. Consider how the current president has deliberately weakened the separation of church and state by making it legal for churches to be political - pastors of tax-exempt churches can now outright advise congregation on who to vote for.

Discovery of life elsewhere threatens the foundation of a lot of religious dogma.

People always claim this, but I'm not convinced. We've had a million scientific discoveries that for all practical purposes disprove a lot of religious claims. People seem to either just adapt their beliefs, ie. things move from literal to symbolic, or people simply choose not to believe or consider the facts despite clear evidence. I don't think simple facts or evidence will ever seriously threaten religious dogma for at least some portion of the population.

I agree that it will, for some portion, but that portion is ever diminishing.

An irrefutable discovery of complex alien life on another planet would, in my opinion, undoubtedly accelerate that rate of diminishment.

In the mean time, many people use the absence of any such discovery, as proof that earth is inexplicably unique so some magic creator deliberately blessed us to be here on this sacred planet.

> The curves from Mars were similar to those produced by LR tests of soils on Earth. It seemed we had answered that ultimate question.

Maybe it was on earth

"Our aspirational goal is to send our first cargo mission to Mars in 2022. The objectives for the first mission will be to confirm water resources, identify hazards, and put in place initial power, mining, and life support infrastructure. A second mission, with both cargo and crew, is targeted for 2024" -- spacex.com/mars

Maybe NASA should book space for a biologist on that flight. A botanist would do.

I know that Musk knows he’s lying. I feel so sorry for his fans.

He's not lying, he's ambitious.

Do you really need a botanist on board? I would think you need space travel / survival / engineering hands on deck who then gather samples and bring them back. A botanist isn’t going to be able to do much on Mars that she can’t do on Earth.

A botanist was the protagonist of The Martian.

Exactly! There’s only one option in the face of overwhelming odds :-)


And an antagonist on the TV series 'Mars'!

I'm guessing that means we're hopelessly off topic by now. Kinda like Reddit, but slower and less pathetic.

That’s fiction...

The reference above is to the book "The Martian" by Andy Weir. Also a movie starring Matt Damon. Good read. Highly recommend!

Xkcd reference that got me to read it: https://xkcd.com/1536/

I disagree. I watched a movie.

The search for life is the way NASA gets funding.

If life is found NASA will not get funding.

Therefore NASA is doing all the science it can before it does a test for life. At least we will be able to say something about what it is and the context that it's in.

Then the plug will get pulled.

I highly, highly, doubt that. If life was found, I expect that the amount of money invested in studying it, would be orders of magnitude what they are getting now.

Science becomes corrupted when the research focuses on finding proof of and ideal instead disproving it.

There are no aliens. With the money wasted on looking for aliens we could have saved millions of lives with clean water, shelter, food and education.

Scientists need to stop deluding themselves and tricking congress into funding pet projects that are so far fetched they border on fraud.

The search for meaning, for answering fundamental questions and for furthering scientific progress has a value, to blame the search for aliens for the state of the world is misguided. Perhaps there are other cuts we could make that would have a bigger impact... "Total world military expenditure rose to $1822 billion in 2018" https://www.sipri.org/media/press-release/2019/world-militar...

I am not blaming the "state of the world" I am saying it's pure waste to spend money on researching fantasy projects.

Military spending is a strawman whataboutism.

It's not about "cuts" it's about sanity. There are no aliens, no proof of aliens, nothing. These programs should not have been started in the first place.

If these peoples lives are so devoid of meaning that they have to spend their lives researching fantasies, they should fund in themselves instead of taking tax payer money for it.

I think military spending is a fair comparison topic even if not directly addressing your point, it's often argued that it's military/space progress that trickles down into improvements for 'the rest of us', though I have my doubts about that nonetheless it provides an incentive beyond the obvious subject being addressed. I take issue with 'fantasy projects', that's what science is, to distill fact from fantasy, it the fantasy in the first instance that inspires the research that provides the answer, if you're essentially saying that we have gathered enough contrary evidence and should now abandon the search and focus on home, well, I can certainly see that perspective and have felt that way at times, but to argue that because we don't know something, we should not waste money finding out the details, well, I think the Wright brothers efforts would have been dismissed as fantasy at the time, glad it did not dissuade them.

>...that's what science is, to distill fact from fantasy...

There is no science being done on vampires, werewolves, dragons and all sorts of other fantasies. Aliens are more fantasy than these.

>...the Wright brothers...

Birds, bugs, even leaves were flying all around them. It was not fantasy in the least. Flying was purely a technical problem.

Aliens do not exist. Spending real money in the pursuit of pretend and non-existent things is pure waste.

What is your evidence that there are no aliens, then?

Proving a negative in a virtually infinite universe looks like an uphill struggle, don't you think?

Exactly. You can't prove a negative, so there are no aliens.

There is not a single shred of evidence _ever_ found to support one iota of research funding. It's science fiction run amok.

> You can't prove a negative, so there are no aliens.

That's self-contradicting.

There is no way to state something that is non-existent is actually non-existent without a bizarre contradiction.

The whole point here is that you do not know that it is inexistent and that you cannot prove it, either.

You only need to find a single instance of aliens to prove that aliens exist.

You need to carefully analyse the whole universe and not find anything to prove that they do not. Proving a negative is hard.

Aliens don't exist. It's total lunacy.

There is more evidence for big foot, lochness monster and vampires than there are for aliens.

Total world expenditure on science projects of any kind at all is downright negligible compared to biggest expenses, such as military, as pointed out...Life conditions, solutions to pollution, most harming diseases etc, could all be fairly easily solved in rather short timespans of 5-20 years probably. The thing that's missing is not the money, it's the humanity's collective consciousness, maturity and responsibility - instead of all I mentioned above, we're still very much busy throwing feces at each other over imaginary borders, or deadly fairytales called religions, and trying to earn more than our peers, so we can buy a shinier thing they will envy.

I agree, we shouldn't be in any of the wars we are in today. But that is like saying we shouldn't try to reign in pork barrel politics because there is so much spent on war. Or we shouldn't try to save on maintenance, software, labor, etc... you name it "because we spend so much on war".

Alien research is faith based, not fact based.

"Ancient explorers should never have ventured on ships to find new lands, for the cost of that could have been used in their countries to better serve the poor" /s

If you're taking about the European explorers - they didn't - they went looking for new trade routes to lands they already knew about. It was about commerce, not exploration. Only after someone "hit it big" (Columbus) did others follow because they realized the commercial opportunities of finding "new" places.

The Polynesians sailing into the unknown Pacific is a different case, but that was most likely (based on what I've read) a situation of "the poor" venturing out to find new lands for themselves, not well funded expeditions paid for by existing kings.

They had _real_ water to follow. Proof was right there, just go a little further.

Aliens is 100% pure fantasy.

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