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False-positive signs of life on exoplanets

exoplanets exomoons life

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#1    Waspie_Dwarf

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Posted 30 April 2014 - 05:48 PM

Research trio suggests exomoon atmospheres could cause false-positive signs of life on exoplanets


phys.org said:

(Phys.org) —A trio of space scientists has published a paper in Proceedings of the National Academy of Sciences in which they suggest that current assumptions regarding using spectral signatures as a means to identify exoplanets that may harbor life, has a major flaw—a false positive could occur if the planet has a moon with an atmosphere that contaminates the spectrum. In their paper, Hanno Rein, Yuka Fujii and David Spiegel of the University of Toronto, the Tokyo Institute of Technology and MIT respectively, point out a major problem with using spectral signatures as a means for finding out if life exists on other planets—moons which can cause the false impression of chemical disequilibrium.

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#2    taniwha

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Posted 01 May 2014 - 10:27 AM

It would be interesting to have a planet evolve life at the same time as its moon.


#3    space-dude1

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Posted 02 May 2014 - 06:56 PM

if we found life outside of earth in our own solar system first,at least we would know for sure.then i would imagine it would be easier get the funding that is needed for more ambitious projects


#4    taniwha

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Posted 02 May 2014 - 11:36 PM

View Postspace-dude1, on 02 May 2014 - 06:56 PM, said:

if we found life outside of earth in our own solar system first,at least we would know for sure.then i would imagine it would be easier get the funding that is needed for more ambitious projects

It might be easier and cheaper to accept that there is other life in the universe so we can move on.


#5    Waspie_Dwarf

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Posted 02 May 2014 - 11:44 PM

View Posttaniwha, on 02 May 2014 - 11:36 PM, said:

It might be easier and cheaper to accept that there is other life in the universe so we can move on.
Yes because the way humanity has made scientific progress is just to make an arbitrary decision on what the truth is and then make no effort to find evidence to back up this decision.

Oh sorry, my mistake, that is the EXACT opposite of how humanity has made scientific progress.

Whether we are alone in the universe is one of the most important and fundamental questions facing science today. Guessing the answer is not a logical or sane way to answer that question.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#6    taniwha

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Posted 03 May 2014 - 12:01 AM

View PostWaspie_Dwarf, on 02 May 2014 - 11:44 PM, said:


Yes because the way humanity has made scientific progress is just to make an arbitrary decision on what the truth is and then make no effort to find evidence to back up this decision.

Oh sorry, my mistake, that is the EXACT opposite of how humanity has made scientific progress.

Whether we are alone in the universe is one of the most important and fundamental questions facing science today. Guessing the answer is not a logical or sane way to answer that question.

It appears scientific logic already calculates that we are not alone in the universe.  Other wise any attempt to find it is an illogical waste of time and money.


#7    Sundew

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Posted 04 May 2014 - 09:50 PM

Unless you are talking about an intelligent alien civilization that is emitting readable bands of energy in a form that we might recognize, i.e. radio waves, then it will be next to impossible to determine if life exists on an exoplanet. And it would be the greatest stroke of luck if we even happen to be listening in that direction when they are broadcasting.

Suppose you have a world with the equivalent of (only) plants and insects that inhale and exhale the same gases as our life does. Could you tell from Earth that these gases are not coming from non-organic geological processes? The sad thing is that, barring some practical space warping technology, it is completely impossible to send a probe to these worlds in any appreciable amount of time and have it return any data.

If we really hope to find alien life, I believe the best bet is still the ice moons of our own solar system's outer planets and even then it may only be microbial, if it exists at all.


#8    Waspie_Dwarf

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Posted 04 May 2014 - 10:56 PM

View Posttaniwha, on 03 May 2014 - 12:01 AM, said:

It appears scientific logic already calculates that we are not alone in the universe.
No it doesn't.

You can not mathematically extrapolate from a single result. Since Earth is the only known planet with life it is impossible to calculate how common life is.

Whilst most scientists believe life is common this is an assumption and is far from being a unanimous opinion.

View Posttaniwha, on 03 May 2014 - 12:01 AM, said:

Other wise any attempt to find it is an illogical waste of time and money.
The law of averages says that one of your opinions, one day will be correct. this, sadly, isn't it.
The very fact that we don't no whether life exists elsewhere in the universe means that searching for it IS a worthwhile and logical pursuit.

You have repeatedly demonstrated that you don't know how science works, now you are proving that you don't even know what science is.

Quote

Science (from Latin scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Source: wikipedia

To be honest, based on past dealings with you, I don't expect you to understand that, so I'll give you a simpler explanation. Science does not accept assumptions or opinions even from experts in the field. For something to be accepted as fact (what scientists call a theory) it must be supported by observation or experimental proof.

The assumption that life exists elsewhere in the universe will remain an unproven hypothesis UNTIL life is observed elsewhere in the universe.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#9    Waspie_Dwarf

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Posted 04 May 2014 - 11:01 PM

View PostSundew, on 04 May 2014 - 09:50 PM, said:

Unless you are talking about an intelligent alien civilization that is emitting readable bands of energy in a form that we might recognize, i.e. radio waves, then it will be next to impossible to determine if life exists on an exoplanet.
Untrue and rather missing the point of the original article all together.

Life, even microbial life, alters the atmosphere of the planet (the oxygen in OUR atmosphere is the result of life).

With powerful enough telescopes it will be possible to take spectra of exoplanet atmospheres and determine their composition. From these results it may be possible to detect life many light years away.

Edited by Waspie_Dwarf, 04 May 2014 - 11:07 PM.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#10    taniwha

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Posted 05 May 2014 - 08:50 AM

View PostWaspie_Dwarf, on 04 May 2014 - 10:56 PM, said:


No it doesn't.

You can not mathematically extrapolate from a single result. Since Earth is the only known planet with life it is impossible to calculate how common life is.

Whilst most scientists believe life is common this is an assumption and is far from being a unanimous opinion.

I see.  My bad.

Quote

The law of averages says that one of your opinions, one day will be correct. this, sadly, isn't it.
The very fact that we don't no whether life exists elsewhere in the universe means that searching for it IS a worthwhile and logical pursuit.

How can you be so sure its worthwhile?  Why does it mean so much to you?

Quote

You have repeatedly demonstrated that you don't know how science works, now you are proving that you don't even know what science is.

Source: wikipedia

To be honest, based on past dealings with you, I don't expect you to understand that, so I'll give you a simpler explanation. Science does not accept assumptions or opinions even from experts in the field. For something to be accepted as fact (what scientists call a theory) it must be supported by observation or experimental proof.

The assumption that life exists elsewhere in the universe will remain an unproven hypothesis UNTIL life is observed elsewhere in the universe.

The assumption that life DOESNT exist elsewhere in the universe could be just as valid a belief dont you think?

Edited by taniwha, 05 May 2014 - 08:51 AM.


#11    Waspie_Dwarf

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Posted 05 May 2014 - 10:02 AM

View Posttaniwha, on 05 May 2014 - 08:50 AM, said:

How can you be so sure its worthwhile?  Why does it mean so much to you?
The real question here is why is scientific progress so meaningless to you?
Why do you not value a better understanding of the universe?
Why do you think ignorance is better than knowledge?
Why would you rather guess than know?


View Posttaniwha, on 05 May 2014 - 08:50 AM, said:

The assumption that life DOESNT exist elsewhere in the universe could be just as valid a belief dont you think?
Read the follow VERY slowly, I have said this to you over and over again, One day it might sink in:-

In science assumptions count for NOTHING, evidence counts for EVERYTHING.

Since assumptions count for nothing all assumptions are equally INVALID if they have no supporting evidence.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#12    Lilly

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Posted 05 May 2014 - 10:22 AM

View PostWaspie_Dwarf, on 05 May 2014 - 10:02 AM, said:


...Since assumptions count for nothing all assumptions are equally INVALID if they have no supporting evidence.

Exactly.

What makes me lean towards there most likely being life elsewhere in the universe (verses there being no other life except here on Earth) is as follows:

1) The basic building blocks for life (amino acids) have indeed been found elsewhere.

2) Conditions on Earth do not appear to be all that extraordinary, other planets are being routinely discovered.

3) The universe is big...very, very big. The odds that there's someplace else with proper conditions for life is pretty good.

That all said, until we find other life we simply don't know for sure.

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#13    Frank Merton

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Posted 05 May 2014 - 10:49 AM

I fully expect that there are life forms a lot of places, maybe even several in the solar system.  That is a worry to me because such planets, each with its own chemistry. may hence be poisoned to possible human settlement.

What I don't expect is that there will be many advanced star-faring civilizations, for reasons I have posted many times.


#14    Waspie_Dwarf

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Posted 05 May 2014 - 11:19 AM

View PostLilly, on 05 May 2014 - 10:22 AM, said:



Exactly.

What makes me lean towards there most likely being life elsewhere in the universe (verses there being no other life except here on Earth) is as follows:

1) The basic building blocks for life (amino acids) have indeed been found elsewhere.

2) Conditions on Earth do not appear to be all that extraordinary, other planets are being routinely discovered.

3) The universe is big...very, very big. The odds that there's someplace else with proper conditions for life is pretty good.

That all said, until we find other life we simply don't know for sure.

View PostFrank Merton, on 05 May 2014 - 10:49 AM, said:

I fully expect that there are life forms a lot of places, maybe even several in the solar system.  That is a worry to me because such planets, each with its own chemistry. may hence be poisoned to possible human settlement.

What I don't expect is that there will be many advanced star-faring civilizations, for reasons I have posted many times.
Equally valid opinions but, of course, the "Rare Earth" hypothesis is also equally valid at the moment.

This contends that for multicellular life to take hold not only do you need a planet in the habitable zone, you also need the following:
  • The correct kind of galaxy. Some galaxies have far greater levels of x-ray and gamma-ray radiation than ours, greater rates of supernovae are also problematic.

  • The correct location within the galaxy. Radiation levels rise and the amount of metals decrease as you approach the centre. Stars are packed closer together and so near-by supernovae and perturbations of planetary and asteroid orbits by passing stars are more common.

  • The right kind of star, so that the planet is not bathed in harmful radiation, the habitable zone is not prohibitively small causing the planet to become tidally locked, the star's output is stable for extremely long periods of time and the star must have formed from a nebula containing enough metals for complex chemistry.

  • The planet must have a continuously stable orbit.

  • The planet must have large moon to produce tidal pools and stabilise the axial tilt of the planet.

  • The planet must be in a solar system that has gas giant in roughly the same position as Jupiter to protect the terrestrial planet from excessive cometary impacts.

  • The planet must be of the right size.

  • The planet must have plate tectonics.

It is possible to make a good case for life being extremely common. It is also possible to make a case for life being extremely rare. If we don't look we will never know which is correct.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#15    Lilly

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Posted 05 May 2014 - 12:56 PM

Indeed, the 'rare Earth hypothesis' has a great deal of evidence in its favour as well.

It could also be that there is other life, but do to its rare occurance, it's in another galaxy far, far away from us. So incredibly far as to essentially render us 'alone' for all intensive purposes!

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