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Are we alone AND what are the ways we can search alien life?
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I think if there were other intelligent life within the solar system we would have had a definite indication of some sort by now.newjerseyrunner said:... Are we likely alone? No, it's likely we're not even alone in our own solar system.
I made no specifications about the intelligence of in solar system life. No evidence is not the same as evidence of nothing. It's highly likely that we are the only intelligence species in this solar system.rootone said:I think if there were other intelligent life within the solar system we would have had a definite indication of some sort by now.
Most of the planets have surface conditions which would one way or another be lethal for carbon based life similar to that on Earth.
Only Mars could be possibly be survivable given an enclosed habitat and adequate shielding from radiation - Mars' atmosphere doesn't cut it as a radiation shield like Earth's does.
Primitive life might be possible in the subsurface water oceans of some gas giant moons, but there is no evidence at present suggesting that this is so.
I'm not sure there's any reason yet to believe that there is life beyond the Earth within our own solar system (aside from the microbes we've sent out from the Earth in our probes). There are some tantalizing possibilities of life in places like Mars, Titan, and Europa, but so far no evidence.newjerseyrunner said:I made no specifications about the intelligence of in solar system life. No evidence is not the same as evidence of nothing. It's highly likely that we are the only intelligence species in this solar system.
I don't think that's accurate. High-energy cosmic rays are not deflected at all by the Earth's magnetic field. Those tend to impact the upper atmosphere, and result in a relatively low level of high-energy radiation that we're exposed to every day. The upper atmosphere also reduces incoming ultraviolet radiation.newjerseyrunner said:Your physics is also incorrect. Earth's atmosphere has little to do with radiation. It protects against UV, but its the magnetic field that deflects the majority of dangerous particles, that's what Mars lacks. It does however have a warm interior and we know that life on Earth is perfectly happy under kilometers of rock.
"Good indicator" is a bit strong. There's a pretty wide gulf between the comparatively simple organic molecules we've detected and life.newjerseyrunner said:There is plenty of evidence of organics, Cassini flew through the jets of Enceladus and confirmed their presence, while not indicative of life, it's a pretty good first indicator. Organic molecules are also present in the surface of Europa.
I specified good FIRST indicator for that reason. I agree, them being there is not a good indicator of life, it is however a good indicator of a potentially inhabited world.Chalnoth said:"Good indicator" is a bit strong. There's a pretty wide gulf between the comparatively simple organic molecules we've detected and life.
The atmosphere is much more important in terms of shielding. Compare the radiation levels from cosmic radiation received on at sea level (shielded by atmosphere and magnetic field) with those on the ISS (shielded by the magnetic field and a thin spacecraft hull) and on the way to moon (shielded only by the spacecraft hull). Sea level to ISS is a factor of roughly 1000, while ISS to moon is a factor of about 2-3.newjerseyrunner said:Your physics is also incorrect. Earth's atmosphere has little to do with radiation. It protects against UV, but its the magnetic field that deflects the majority of dangerous particles, that's what Mars lacks. It does however have a warm interior and we know that life on Earth is perfectly happy under kilometers of rock.
Sorry, can you clarify?newjerseyrunner said:I specified good FIRST indicator for that reason. I agree, them being there is not a good indicator of life, it is however a good indicator of a potentially inhabited world.
Inhabited in the sense that there is anything at all living on it, not intelligent species. And organic molecules being a good indicator of POTENTIAL, not actually inhabited. In such a way that seeing ice caps and dark channels on the Martian landscape was a good indicator that Mars was potentially inhabited in 1900.DaveC426913 said:Sorry, can you clarify?
You seem to have said that organic molecules are a good indicator of a potentially inhabited world.
Except that they weren't a good indicator. (As on the Moon, there is also ice, but certainly no life, therefore ice is not a good indicator of life)newjerseyrunner said:In such a way that seeing ice caps and dark channels on the Martian landscape was a good indicator that Mars was potentially inhabited in 1900.
The atmosphere would protect the surface from solar wind as well, if necessary.newjerseyrunner said:Oh. The magnetic field is what protects the atmosphere from the solar wind, but the atmosphere itself is what protects the planet's surface from high energy radiation?
Again, I said nothing about indicating habitation. I only said it indicates potential. Enceladus indicates potential, Anthe doesn't. That's all I mean by indicating, the way I was using it, any object with liquid water and simple organics has potential, as well as Titan and places with potential for exotic life. I only meant to illustrate that the building blocks of known life are known to exist there. I should have been more careful with wording.@mfb, Why doesn't the solar wind rip Venus' atmosphere off? I know the composition of the atmosphere is mostly fairly heavy molecules, is Venus's gravity enough to maintain it or is there something else going on there?DaveC426913 said:Except that they weren't a good indicator. (As on the Moon, there is also ice, but certainly no life, therefore ice is not a good indicator of life)
Just like Enceladus, organics are not a good indicator of habitation.
So I'm not sure why you're saying they are.
If you figure it out completely, write a paper...newjerseyrunner said:Why doesn't the solar wind rip Venus' atmosphere off?
Organic molecules are a necessary condition for organic life, but nowhere near sufficient.newjerseyrunner said:I specified good FIRST indicator for that reason. I agree, them being there is not a good indicator of life, it is however a good indicator of a potentially inhabited world.
Chalnoth said:Organic molecules are a necessary condition for organic life, but nowhere near sufficient.
You also need some sort of out-of-equilibrium energy process to sustain any life, as well as an environment that is sufficiently gentle to prevent immediate breakdown of molecules complex enough for self replication.
I do expect that the formation of life is essentially inevitable given the right conditions, I'm just not sure those conditions existed anywhere but the Earth within our own solar system. I strongly support searches for life elsewhere in the solar system, I'm just not sure we yet have cause for optimism.
Paragraphs!ogg said:Unfortunately, many... ...the atmosphere at all.
And funilly enough I was looking for something interesting to spend a couple of hours watching while I had nothing better to do.newjerseyrunner said:Funny how often my Youtube queue has had a video about something I've seen on this forum.
If it's too long the short version is ...
Chalnoth said:"Our best bet for finding life outside of our solar system is by looking at the atmospheres of planets orbiting other stars. As far as we know, life is the only thing that can maintain an atmosphere that has out-of-equilibrium chemistry."
Depends on the power of the emitter and the distance.Monsterboy said:so according to this article the SETI can only work if an alien message is beamed directly towards earth
Depends on the intent of the emission. In ~20 years we should have the technology to discover Earth (if we wouldn't be on it) as likely candidate for life from tens of lightyears away, even without finding radio emissions. Aliens might have studied our atmosphere and considered Earth as possible place for intelligent life.Monsterboy said:that's highly highly unlikely right
Right.Monsterboy said:About that narrow band signal , it refers to the narrow band of frequencies?
It's possible that intelligent aliens could decide to send a highly directional signal to Earth if they already had a good reason to suspect there was a liklihood of the message being received.Monsterboy said:... SETI can only work if an alien message is beamed directly towards Earth , that's highly highly unlikely right ?
That's a fairly fanciful definition of intelligence, IMO. I think intelligence is, by definition, distinct from complex behavior. Bees certainly have complex behavior, but the reason they haven't contacted us is because they are not sentient.Chronos said:For example, bees behave in an organized and purposeful manner. etc
If something would have ended life on Earth 1 million years ago Earth would never have developed such a species.rootone said:Then again perhaps a technological species becomes inevitable at some point once life has evolved beyond the level of plants.
True, but life here seems to have survived near extinction several times.mfb said:If something would have ended life on Earth 1 million years ago Earth would never have developed such a species.
A billion years is oodles of time to evolve an alternate energy extraction mechanism.mfb said:And there is always the timescale. The sun becomes more luminous over time, which reduces the CO2 content of the atmosphere. At some point, it will become too low for photosynthesis. In roughly a billion years the greenhouse effect (based on water, not CO2) kills whatever remained on the surface or in the oceans.
Some of the most common methods include searching for biosignatures (evidence of life) in the atmospheres of other planets, analyzing data from radio telescopes for potential signals from extraterrestrial civilizations, and sending out spacecrafts to explore other planets and moons in our solar system for signs of life.
Yes, scientists have developed advanced technology such as telescopes, spectrometers, and probes that can help us detect potential signs of alien life. However, the technology is limited and we are still learning how to interpret the data we collect.
Scientists look for certain conditions that are necessary for life to exist, such as the presence of water, a stable atmosphere, and a source of energy. They also study the planet's distance from its star and its composition to determine if it could potentially support life.
Yes, there are several ongoing projects and missions, such as the SETI (Search for Extraterrestrial Intelligence) program, the Kepler Space Telescope, and the Mars 2020 mission, that are dedicated to searching for signs of alien life in different ways.
It is difficult to determine the likelihood of finding alien life since we are still exploring and learning about the vastness of our universe. However, with advancements in technology and ongoing research efforts, it is possible that we may find evidence of alien life in the near future.