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I don't think we have enough data to be sceptical about the presence of certainty of life on other planets. We've only found ~3,700 planets other than Earth - a

by JoBrad 9y ago

I don't think we have enough data to be sceptical about the presence of certainty of life on other planets. We've only found ~3,700 planets other than Earth - and only ~20 of those are near the size of Earth[0]. We couldn't even see those planets directly until very recently, so it doesn't seem certain (to me, a layman) that we could even identify Earth as having life, at the same resolutions. That's assuming that we would recognize life, if we saw it. (Side note: Children of Men is a book I recently read that touches on this topic. ) I'll admit that I am very optimistic about the presence of advanced life on planets other than Earth, so this is definitely influencing my outlook. [0] https://www.google.com/amp/s/arstechnica.com/science/2016/05/number-of-potentially-habitable-planets-in-our-galaxy-tens-of-billions/%3Famp%3D1 https://www.google.com/amp/s/arstechnica.com/science/2016/05...

EGreg 9y ago
But we have explored Mars and the moon!
- rpedela 9y ago
  Not really, not at the level necessary to rule out the existence of life. Both Jupiter and Saturn have moons that may have life based on our current understanding of life and its origins. And Mars may still have life that we haven't found yet. The truth is that we are just now able to start seriously asking the question: is there life elsewhere in the universe? It may take a few hundred years to answer that question.
- observation 9y ago
  Perhaps in the way a holidaymaker considers themselves aware of other cultures! For real exploration we have to be living there. This is just because it focuses our attention, allows large numbers of people to be aware of their surroundings in a non-theoretical way.
  - EGreg 9y ago
    Once you live there, you can fool yourself that you found microbes when in fact you spread them! That's why everything is decontaminated before blasting off to Mars :)
- roywiggins 9y ago
  We've only gone a couple of inches below the surface. Mars could have microbes hiding a kilometer down and it's hard to know if we would be able to tell.
chiefalchemist 9y ago
But, what does life have to do with an earth like planet? And when you study the history of the earth you come to realize that life as we know it today is the result of countless events, some of them catastrophic. As I understand it, if you simply shifted the location of Antarctica, that would change ocean currents, this effect weather, and so one. Life as we know it today might not exist if it weren't for Antarctica. And the fact is, we'd be toast, literally, without a magnetic field. That's more important that planet size. How many planets have we found with a magnetic field like ours? What are THOSE odds? So it seems to me, an earth like planet (in size) is a cute exercise but in the end close to irrelevant.
- rpedela 9y ago
  Our life planet data set is an N=1 so we are searching what we know. It is certainly possible life is found on non-Earth-like planets and isn't carbon-based, however we don't have any examples so we don't know what to look for. The initial search is focusing on Earth-like planets because we know the signs of life in that case. As for Antarctica, that may true but there would still be life, maybe not humans, on Earth. The fossil record shows there was life before Antarctica existed.
  - roywiggins 9y ago
    Literally billions of years older, in fact...
- roywiggins 9y ago
  Life is much, much older than Antarctica. It's only about 25 million years old (per Wikipedia). Humans might not exist but life would be pretty much the same without it, insofar as there would be large critters and plants wandering about and eating each other.
  - chiefalchemist 9y ago
    Allow me to clarify. Life is a function of the broader ecosystem. Antarctica was an example of some we take for granted, but it has/has had an impact on the Earth's temps, weather, etc. My broader point was that humans today have a fair number of random events to thank for having led to the human species. So it's not only a question of life (in the broader abstract) but also planet history. Planets similar to earth? Probably countless. Those with a similar history is, I presume, significantly rare. Perhaps zero?
agumonkey 9y ago
What I am curious about is non carbon based lifeforms.

by JoBrad 9y ago

EGreg 9y ago

But we have explored Mars and the moon!

rpedela 9y ago
Not really, not at the level necessary to rule out the existence of life. Both Jupiter and Saturn have moons that may have life based on our current understanding of life and its origins. And Mars may still have life that we haven't found yet. The truth is that we are just now able to start seriously asking the question: is there life elsewhere in the universe? It may take a few hundred years to answer that question.
observation 9y ago
Perhaps in the way a holidaymaker considers themselves aware of other cultures! For real exploration we have to be living there. This is just because it focuses our attention, allows large numbers of people to be aware of their surroundings in a non-theoretical way.
- EGreg 9y ago
  Once you live there, you can fool yourself that you found microbes when in fact you spread them! That's why everything is decontaminated before blasting off to Mars :)
roywiggins 9y ago
We've only gone a couple of inches below the surface. Mars could have microbes hiding a kilometer down and it's hard to know if we would be able to tell.

chiefalchemist 9y ago

But, what does life have to do with an earth like planet? And when you study the history of the earth you come to realize that life as we know it today is the result of countless events, some of them catastrophic. As I understand it, if you simply shifted the location of Antarctica, that would change ocean currents, this effect weather, and so one. Life as we know it today might not exist if it weren't for Antarctica. And the fact is, we'd be toast, literally, without a magnetic field. That's more important that planet size. How many planets have we found with a magnetic field like ours? What are THOSE odds? So it seems to me, an earth like planet (in size) is a cute exercise but in the end close to irrelevant.

rpedela 9y ago
Our life planet data set is an N=1 so we are searching what we know. It is certainly possible life is found on non-Earth-like planets and isn't carbon-based, however we don't have any examples so we don't know what to look for. The initial search is focusing on Earth-like planets because we know the signs of life in that case. As for Antarctica, that may true but there would still be life, maybe not humans, on Earth. The fossil record shows there was life before Antarctica existed.
- roywiggins 9y ago
  Literally billions of years older, in fact...
roywiggins 9y ago
Life is much, much older than Antarctica. It's only about 25 million years old (per Wikipedia). Humans might not exist but life would be pretty much the same without it, insofar as there would be large critters and plants wandering about and eating each other.
- chiefalchemist 9y ago
  Allow me to clarify. Life is a function of the broader ecosystem. Antarctica was an example of some we take for granted, but it has/has had an impact on the Earth's temps, weather, etc. My broader point was that humans today have a fair number of random events to thank for having led to the human species. So it's not only a question of life (in the broader abstract) but also planet history. Planets similar to earth? Probably countless. Those with a similar history is, I presume, significantly rare. Perhaps zero?

agumonkey 9y ago

What I am curious about is non carbon based lifeforms.