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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

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-78138144/ https://www.smithsonianmag.com/science-nature/life-on-mars-7...

ianai 7y ago
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.
- imglorp 7y ago
  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.
  - powerbroker 7y ago
    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.
    - xvector 7y ago
      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.
      - Hextinium 7y ago
        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.
        CryptoPunk 7y ago
        Apparently Dyson spheres can be undetectable with IR telescopes: https://www.tillett.info/2016/08/03/carnot-efficient-dyson-spheres-are-undetectable-by-infrared-surveys/ https://www.tillett.info/2016/08/03/carnot-efficient-dyson-s...
        cgriswald 7y ago
        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.
    - fsloth 7y ago
      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.
      - philwelch 7y ago
- asdff 7y ago
  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.
  - rzzzt 7y ago
    "However improbable", Sherlock Holmes is often brought up in cases like this...
    - stan_rogers 7y ago
      That's contingent on eliminating the impossible.
      - cameron_b 7y ago
        the scope of which begs a complete understanding of the possible
    - cgriswald 7y ago
      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.
      - rzzzt 7y ago
        Holmes does appear to be operating under the closed-world assumption: https://en.wikipedia.org/wiki/Closed-world_assumption https://en.wikipedia.org/wiki/Closed-world_assumption
  - jf- 7y ago
    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.
- jayalpha 7y ago
  It also depends on your definition of live. The best broad test to look for life would be to look for an entropy source.
- mnky9800n 7y ago
  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.
  - em-bee 7y ago
    the keyword here is expectation. that expectation may be misguided.
  - pharrington 7y ago
    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.

ianai 7y ago

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.

imglorp 7y ago
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.
- powerbroker 7y ago
  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.
  - xvector 7y ago
    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.
    - Hextinium 7y ago
      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.
      - CryptoPunk 7y ago
        Apparently Dyson spheres can be undetectable with IR telescopes: https://www.tillett.info/2016/08/03/carnot-efficient-dyson-spheres-are-undetectable-by-infrared-surveys/ https://www.tillett.info/2016/08/03/carnot-efficient-dyson-s...
      - cgriswald 7y ago
        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.
  - fsloth 7y ago
    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.
    - philwelch 7y ago
asdff 7y ago
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.
- rzzzt 7y ago
  "However improbable", Sherlock Holmes is often brought up in cases like this...
  - stan_rogers 7y ago
    That's contingent on eliminating the impossible.
    - cameron_b 7y ago
      the scope of which begs a complete understanding of the possible
  - cgriswald 7y ago
    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.
    - rzzzt 7y ago
      Holmes does appear to be operating under the closed-world assumption: https://en.wikipedia.org/wiki/Closed-world_assumption https://en.wikipedia.org/wiki/Closed-world_assumption
- jf- 7y ago
  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.
jayalpha 7y ago
It also depends on your definition of live. The best broad test to look for life would be to look for an entropy source.
mnky9800n 7y ago
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.
- em-bee 7y ago
  the keyword here is expectation. that expectation may be misguided.
- pharrington 7y ago
  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.