Reflections (and questions) on Life in the Universe

[mangekyou-sama]

After various playthroughs of space games like KSP, SpaceEngine, Universe Sandbox 2; after reading through various posts here in the Science Labs (most of them very enlightening), I'm still nowhere close to fully comprehending the scale of the universe and its secrets. I've also read through various articles discussing the possibility of life outside the solar system. I've even read this thing about the Drake equation where it seeks to predict life through various parameters. It's fascinating how far can humans go just to justify the possibility of life.

I strongly believe in life outside the solar system. The universe is just so vast; Earth is merely a dust in it and it can't be possible that we're the only ones - and I've always been intrigued on what could they look like. Let's not talk about microbes. Let's just for a moment talk about multicellular organisms that might have evolved in other planets. Do they look like anything that we see in the movies? Humanoid? Are they remotely close to the Zerg or the Protoss that we saw in SC?

Considering that they have technology, how does OUR technology compare to theirs? Do they have the concept of science? Earth has Newton, Einstein, Kepler; do these other creatures have their own prodigies? Have they gone down the path of chemistry? If so what's their own name for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur? What is their definition of life? Just as we have our own sets of universal constants, do they have their own? Are they a peaceful race? Have they had their own wars in their planets? Do they have a concept of government? Do they ever fight for oil just as we humans do here on Earth?

You see, thinking about the universe has produced more questions than answers. These questions will remained answered (in my lifetime at least). But surely it can't be just me who thinks the same way. I would like to know your thoughts, insights. After all, you guys might know something that I don't.

Feel free to share! I'm very eager to reading your replies!

[Ralathon]

For most of these things we simply don't know the answer. We only know of 1 planet with life and we're standing on it. You can't extrapolate from a single data point. But if I had to guess I'd say they look more like the Zerg than the humanoid aliens that Star Trek uses. Simply because zerg have such a wide variety of shapes that it seems likely that an arbitrary alien would share similarities with at least one of them.

As for their science and technology. The laws of physics apply to the entire universe. So if they invent science they'll come to the same conclusions as we have. Perhaps they'll have a different interpretation of the laws, but they'll know that metals conduct electricity and that the universe was created in the big bang etc.

For the rest we can say absolutely nothing of them until we actually encounter them. If they exist at all.

[ibeinsane]

What is worth considering is that life on earth existing a long time before humanoids, even mammals for that matter, starting with fish, reptiles and birds. Generally I think it is accepted that we would be most likely to find primitive life in the oceans. Beyond that, for science and extensive material manipulation for tools etc then some form of hands and fingers are required. This would almost universally be required for an intelligent race to have developed 'technology'. Of course you also require an advanced brain, which in the development of life on earth has generally required mammals to maintain sufficient heat and energy. This may not be the case on other planets and climates but this becomes speculation or debate on what defines intelligence.

For science and technology, although science is science and the rules of physics are the same it is not necessary that they have the same type of technologies as us. Out technologies developed from our surroundings and requirement to develop material for defence, warmth and food etc. For instance electricity is from our production of metals. Our ability to process metals came from our drive to develop stronger metal based weapons to fight with. Without this early drive for metal refining our current source of electricity for power could well be based on other materials. The exact same argument is posed for fossil fuels.

Add to this that the presence of fossil fuels is due to the fact we had masses of life on an early planet several hundred million years ago. If Earth did not have masses of forests, ocean life and dinosaurs we would not have fossil fuels, electricity or even the early metal weapons to fight with. From that argument you could suggest that our technology is actually due to the dinosaurs and the late rise of mammals to Earth. Imagine how our technology could have developed without fossil fuels, no oil for heat, no coal for fire to smelt iron or mould copper/brass. This would have limited our war making ability quite severely and also our ability to generate electricity to develop our current technologies.

We have statistics on our side due to the number of planets but could the same scenario have developed elsewhere? Early life abundant planet, cataclysmic death of everything allowing the evolution of small mammals whilst providing huge quantities of fossil fuels in order to start technology development in a highly evolved mammal.

In my opinion, although life is almost certainly elsewhere in the universe, and on that basis probably intelligent life also, the age of the universe, the vast distances of the universe and our current limited knowledge of the longevity of species', we are very unlikely to meet another life form of this type. Of course this is the case unless we develop principles far beyond our current understanding to travel much faster than the speed of light before we succumb to a natural or unnatural disastrous fate.

The ramblings of a bored physicist with too much time at work.

PS, As above, we just don't know and the answers.

[Scotius]

We can wax philosophically all day here, but no one will give you answers you look for We need more data. We need to learn how life appeared on Earth. We need to discover life, or traces of it beyond our planet. We need to find aliens, and make contact with them. We need to understand them. Until it happens there will be no answers.

[KerikBalm]

Do they look like anything that we see in the movies? Humanoid? Are they remotely close to the Zerg or the Protoss that we saw in SC?

I'm going to go with no, but then its a matter of "how remote", particularly that with sufficient "remotness", you can say many zerg resemble arthropods on Earth.

Considering that they have technology, how does OUR technology compare to theirs?

Some much better, some much worse. Life has been here for 4 billion years on Earth, another species may be billions of years ahead of us, or billions behind us. Most technological species will not be remotely close to us simply because of the vastness of time.

Do they have the concept of science? Earth has Newton, Einstein, Kepler; do these other creatures have their own prodigies? Have they gone down the path of chemistry? If so what's their own name for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur?

I'm sure they have prodigies, if they evolve, they'll have variability, which will lead to those at the far end of the bell curve from time to time.

Who says they have names?

Just as we have our own sets of universal constants, do they have their own?

Universal constant is universal.

They will discover C, I'm sure

Are they a peaceful race? Have they had their own wars in their planets?

Are we a peaceful race? they will certainly have known war. Competition for resources will be universal.

Do they ever fight for oil just as we humans do here on Earth?

Or metals, or food, they will fight for resources, or they did in their past, I'm sure.

[trekkie_]

The universe will be very much like the chain of life on earth. You will always have more prey animals than predators for example. That's why there's over 70 billion cows on earth. So we will probably have tons more primitive life than advanced life. For all we know, we're the only ones to ever get this far. Technology isn't necessarily created with tools and hands, it can be evolved.

We have to realize that we are a natural result of universe physics, which means life, even life similar to us, will develop somewhere eventually.

The problem with life is there are soo many criteria that must take place in a somewhat specific order for life to develop, thrive, and evolve.

One thing we have to consider is that there may never be a way to go as fast as light, let alone faster. In the universe even the speed of light is rather slow compared to all the space. We may have to expect that even if life is out there, the universe is too vast for interstellar contact. And we're also moving throughout the galaxy. When dinosaurs were alive, the planet was on the other side of the galaxy. We could have already passed up an inhabited world before we evolved, and we'll both probably be extinct by the time it comes around again.

[Kryten]

For a considerable majority of the time there has been life on earth, there hasn't been anything recognisable as an animal. Tool use, even in the most basic of forms, isn't likely to be more than 2 or 3 hundred million years old, about a tenth of life's span so far; and technological advancement has happened in the last evolutionary blink of an eye. The chance of all of these things emerging again, even with the assumption of life to start with, isn't high.

[magnemoe]

After various playthroughs of space games like KSP, SpaceEngine, Universe Sandbox 2; after reading through various posts here in the Science Labs (most of them very enlightening), I'm still nowhere close to fully comprehending the scale of the universe and its secrets. I've also read through various articles discussing the possibility of life outside the solar system. I've even read this thing about the Drake equation where it seeks to predict life through various parameters. It's fascinating how far can humans go just to justify the possibility of life.

I strongly believe in life outside the solar system. The universe is just so vast; Earth is merely a dust in it and it can't be possible that we're the only ones - and I've always been intrigued on what could they look like. Let's not talk about microbes. Let's just for a moment talk about multicellular organisms that might have evolved in other planets.

I think its high chance of life, life begun on earth less than 200 million years after it was possible. This indicate that its relatively common.

We got pretty advanced life not long after we got decent with oxygen in the atmosphere, 500 million years ago, this was also delayed by an global ice age.

Do they look like anything that we see in the movies? Humanoid? Are they remotely close to the Zerg or the Protoss that we saw in SC?

The Protoss look plausible however straiten the legs, legs like that work on small animals not large, think the back leg of a horse.

Giant bugs has problems as I understand its problem with large creatures with external skeleton, it start to get hard to make joint who can manage.

changing the shell then growing would also be very hard.

My guess is head, two arms and two legs, six limbs might also work well, might be an benefit as its easier to use the two forward ones as arms then walking on two legs.

Considering that they have technology, how does OUR technology compare to theirs? Do they have the concept of science? Earth has Newton, Einstein, Kepler; do these other creatures have their own prodigies? Have they gone down the path of chemistry? If so what's their own name for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur? What is their definition of life? Just as we have our own sets of universal constants, do they have their own? Are they a peaceful race? Have they had their own wars in their planets? Do they have a concept of government? Do they ever fight for oil just as we humans do here on Earth?

You see, thinking about the universe has produced more questions than answers. These questions will remained answered (in my lifetime at least). But surely it can't be just me who thinks the same way. I would like to know your thoughts, insights. After all, you guys might know something that I don't.

Feel free to share! I'm very eager to reading your replies!

First, if we run into intelligent aliens they will either be stone age or far more advanced than us, chances of catching them in the 5000 year gap from stone age to more advanced is very small.

If they are more advanced they have all the science, same rules everywhere, also an government, as for wars it depend a lot on how they solve conflicts, they would be alien and don't think like us.

As for fighting over oil, either they have not discovered it or stopped using it long ago.

My guess is that they will eat or probes. http://imgur.com/QNnA8iM

[rtxoff]

My guess is that similar conditions could lead to similar lifeforms on two planets. If there is some planet that has the same properties like earth there is an great chance that life like we know could (have) evolve(d) there.

[nuclearping]

Life steps into existence whenever the minimal requirements are met. For instance hydrothermal vents in deep sea (black smokers / white smokers) have been found to contain a wide variety of fauna, something "scientists" didn't think of its possibility, unless they saw it. There are lots of Extremophiles, who seem to defy our understanding of life and how it arises.

So for me the possibility of life on other planets is like 100%. I'm even pretty sure we will find extraterrestrical life forms in our very solar system. Maybe Europe, Titan, even Venus (higher atmosphere) is possible and already have been discussed.

But well, "intelligent" life is something different. And also very philosophical. Because what is intelligence? Can we really claim that we are "intelligent"? Does Earth inhabit "intelligent" life? I wouldn't say yes for sure.

Yes, you can look in Wikipedia for the definition of "Intelligence". But thats not what I mean. We are pretty self-destructive, self-centered, have no harmony with ourself, we have a small vision and we are pretty dogmatic. Science is our religion. Things not approved by science are pretty much irrelevant. Before Science it was the Church. Things not approved by Church were nonsense and irrelevant. We wage wars 24/7 and fight over resources and land masses. We discriminate others because of their beliefs, thoughts, sexuality, color, wealth (or poverty), appearance, etc.

The rich trying to become richer, at the cost of the not-so-rich (or even pi**-poor). Like 75% of world wide wealth is hold by like 25% of people. Etc. Etc. Space? LoL. Who cares. Worthless since it costs too much money. And what can you get out of it anyway?

So thats our situation. We are too busy with ourselfs to look over the plate's edge. We have potential to become an intelligent life form. Yes. But from my point of view, we (meaning humanity as a whole) are not there yet, since we are overall still acting like animals or primates, since we do follow the same basic routines: Eat, Sleep, Mate, Poop, Fight. Doing it with more style doesn't necessarily mean we are intelligent.

[Kryten]

Life steps into existence whenever the minimal requirements are met. For instance hydrothermal vents in deep sea (black smokers / white smokers) have been found to contain a wide variety of fauna, something "scientists" didn't think of its possibility, unless they saw it. There are lots of Extremophiles, who seem to defy our understanding of life and how it arises.

Complete nonsense. We've evidence of life 'stepping into existence' precisely once.

[magnemoe]

Life steps into existence whenever the minimal requirements are met. For instance hydrothermal vents in deep sea (black smokers / white smokers) have been found to contain a wide variety of fauna, something "scientists" didn't think of its possibility, unless they saw it. There are lots of Extremophiles, who seem to defy our understanding of life and how it arises.

So for me the possibility of life on other planets is like 100%. I'm even pretty sure we will find extraterrestrical life forms in our very solar system. Maybe Europe, Titan, even Venus (higher atmosphere) is possible and already have been discussed.

But well, "intelligent" life is something different. And also very philosophical. Because what is intelligence? Can we really claim that we are "intelligent"? Does Earth inhabit "intelligent" life? I wouldn't say yes for sure.

Yes, you can look in Wikipedia for the definition of "Intelligence". But thats not what I mean. We are pretty self-destructive, self-centered, have no harmony with ourself, we have a small vision and we are pretty dogmatic. Science is our religion. Things not approved by science are pretty much irrelevant. Before Science it was the Church. Things not approved by Church were nonsense and irrelevant. We wage wars 24/7 and fight over resources and land masses. We discriminate others because of their beliefs, thoughts, sexuality, color, wealth (or poverty), appearance, etc.

The rich trying to become richer, at the cost of the not-so-rich (or even pi**-poor). Like 75% of world wide wealth is hold by like 25% of people. Etc. Etc. Space? LoL. Who cares. Worthless since it costs too much money. And what can you get out of it anyway?

So thats our situation. We are too busy with ourselfs to look over the plate's edge. We have potential to become an intelligent life form. Yes. But from my point of view, we (meaning humanity as a whole) are not there yet, since we are overall still acting like animals or primates, since we do follow the same basic routines: Eat, Sleep, Mate, Poop, Fight. Doing it with more style doesn't necessarily mean we are intelligent.

Intelligence in this setting is pretty easy to identify at lest of higher levels, my probe eating catgirl above would be obvious. Some danger to put the bar to high, like require starships to be considered an technical civilization. A bit harder then you move back, would erectus be seen as intelligent, he spread pretty wide, how about habilis? then it start to get hard.

I guess intelligence is the great filter, its rare and if someone start to get intelligent its an huge danger it stop at erectus level who is to stupid to even get far in the stone age.

[magnemoe]

Complete nonsense. We've evidence of life 'stepping into existence' precisely once.

True, but it happened fast, this indicates its easy. Not a proof but an good indication, Say life started after 100 million years, if life in average happens once every 100 mil/ year we are average, if the average is a billion year we was one of the 10% lucky (correct me if I'm wrong chances might be lower than 10%)

The point is that its more probably that life is easy than its hard and we was lucky, and 1 billion year just increase the time before you get life.

Now if life is very rare, say average 1/100 billion years we start to get into the lottery ticket lucky area, simplest solution is that life is common.

[KerikBalm]

Well it appears in the geological record fast, but we don't have much of anything before the late-heavy bombardment.

Traditionally, its thought that the LHB would have sterilized any life that was on earth... but then again, it would have ejected a lot of material into space, which could have reseeded the Earth once it was over.

Taking a limited form of litho-panspermia into consideration: Venus's oceans would have both appeared, and dissappeared, before ours, and of course Mars also seems to have had an ocean. If we consider the possibility that life started before the LHB... it could have happened a lot "slower"

We won't know about mars until we start going into the subsurface, but I suspect it is dead. Same with Europa - if it is there, its genetic code will tell us if it shares a common origin with Earth, which will inform our guesses about how easy it is for life to start.

The place where life can survive, and the places where life can start, are not neccessarily the same thing.

I suspect Europa will have no indigenous life.

And venus? you've got to be kiddin me.

Its upper atmosphere may be cooler, but its also chemially pretty homogenous. Its severely depleted in hydrogen containing compounds (like water). Its mostly CO2, but you an't get very interesting carbon structures if you can't have hydrocarbons, and there's almost no hydro- to go with the carbon. Not to mention the turnover rate it would have due to mixing with other layers of the atmosphere, the intense radiation, and sparse nutrients. There's no way life could replicate fast enough there to beat the turnover rate, even if you could have life in a carbon rich, hydrogen poor environment.

[nuclearping]

Complete nonsense. We've evidence of life 'stepping into existence' precisely once.

Ok, then lets say we have evidence that life on this planet "steps into existence" whereever it can, even in locations we thought life is impossible due to hazardous environments. Hence the simplest conclusion is that if this has happened on Earth, the chances are very high this has happened on other Planets (and / or Moons) aswell.

[Kryten]

You can't draw conclusions from a premise that you just made up. Conditions that life can adapt to and conditions that life can arise in can't just arbitrarily decided to be the same.

[nuclearping]

The place where life can survive, and the places where life can start, are not neccessarily the same thing.

True. But if you consider Earth's history, life has had a hard time here aswell, multiple times and still managed to persist and even evolve.

Same with Europa

I suspect Europa will have no indigenous life.

And venus? you've got to be kiddin me.

I don't want to start a fundamental debate here. The ideas of life on Venus, Titan or Europe aren't new and actually come from modern conclussions and theorys.

Europa:

http://earthguide.ucsd.edu/virtualmuseum/litu/10_3.shtml

http://www.space.com/26905-jupiter-moon-europa-alien-life.html

Titan:

http://www.space.com/17919-life-on-titan-saturns-cold-moon-fascinates-scientists-video.html

http://phenomena.nationalgeographic.com/2014/03/17/saturns-largest-moon-would-host-really-really-weird-life/

Venus:

http://www.dailygalaxy.com/my_weblog/2009/07/could-atmosphere-of-venus-harbor-life-experts-say-yes.html

http://news.discovery.com/space/alien-life-exoplanets/are-venus-clouds-a-haven-for-life-130516.htm

* EDIT *

You can't draw conclusions from a premise that you just made up.

I didn't make up anything. You can read about these things all above the internet and see it on Discovery.

And on the other hand, you're drawing conclusions from things we don't know. Don't you?

If you are part of the "I don't believe it until I see it"-group, then thats ok. I'm part of the other group tho.

Edited September 19, 2014 by nuclearping

[Seret]

I've even read this thing about the Drake equation where it seeks to predict life through various parameters.

Strictly speaking the Drake Equation doesn't make any attempt to predict anything. It was originally devised by Frank Drake as a way of setting the agenda for a conference in the early days of SETI. His objective was to try and concentrate thinking around what parameters would influence the chance of detecting an alien civilisation. The fact that the equation has become so widely known speaks to the fact that Drake's thinking was sound.

However, people are bound to use it to try and put a number on the actual probability. That's fine, except for the fact that we don't have data for several of the variables. As long as you acknowledge that any attempt to plug numbers into those is really just a guess (and therefore carries no weight in serious conversation) then that's ok. From time to time people do try and quote it as if it's actually a scientific tool capable of making predictions, which is completely wrong.

[KerikBalm]

True. But if you consider Earth's history, life has had a hard time here aswell, multiple times and still managed to persist and even evolve.

Of course it evolved

It started once, and from all indications, when it was relatively easy to do so.

And from all indications, there continued to be easy places for continued existence, even during mass extinctions. We've never had something that even came close to making Earth uninhabitable all over.

I don't want to start a fundamental debate here. The ideas of life on Venus, Titan or Europe aren't new and actually come from modern conclussions and theorys.

Titan, yes, Europa, yes.

Venus: no

Your layman's magazine articles not withstanding.

Yes, the conditions in the upper atmosphere are such that if you were to place an aerosol of bacteria in it, they may not immediately die, but they would need to reproduce and disperse pretty darn fast to beat the death rate from mixing with the rest of the atmosphere... all the while doing this in air lacking any signifcant water vapor or hydrogen containing compounds.

Its nothing but wishful thinking

I didn't make up anything. You can read about these things all above the internet and see it on Discovery.

Discovery is not a reliable source, the sooner you realize that, the sooner we can have an intelligent conversation.

You did make up what he claimed:

lets say we have evidence that life on this planet "steps into existence" whereever it can

That is a premise you just made up "lets say" because we don't actually have any evidence for it (in fact, we have quite the opposite, 1 origin of life for the entire planet, not multiple origins over and over again all over the planet).

Then you attempted to draw conclusions from it.

He was 100% accurate.

And on the other hand, you're drawing conclusions from things we don't know. Don't you?

If you are part of the "I don't believe it until I see it"-group, then thats ok. I'm part of the other group tho.

He didn't draw conclusions, he criticized your logic.

Also, you should google Russel's teapot.

[magnemoe]

Well it appears in the geological record fast, but we don't have much of anything before the late-heavy bombardment.

Traditionally, its thought that the LHB would have sterilized any life that was on earth... but then again, it would have ejected a lot of material into space, which could have reseeded the Earth once it was over.

Taking a limited form of litho-panspermia into consideration: Venus's oceans would have both appeared, and dissappeared, before ours, and of course Mars also seems to have had an ocean. If we consider the possibility that life started before the LHB... it could have happened a lot "slower"

We won't know about mars until we start going into the subsurface, but I suspect it is dead. Same with Europa - if it is there, its genetic code will tell us if it shares a common origin with Earth, which will inform our guesses about how easy it is for life to start.

The place where life can survive, and the places where life can start, are not neccessarily the same thing.

I suspect Europa will have no indigenous life.

And venus? you've got to be kiddin me.

Its upper atmosphere may be cooler, but its also chemially pretty homogenous. Its severely depleted in hydrogen containing compounds (like water). Its mostly CO2, but you an't get very interesting carbon structures if you can't have hydrocarbons, and there's almost no hydro- to go with the carbon. Not to mention the turnover rate it would have due to mixing with other layers of the atmosphere, the intense radiation, and sparse nutrients. There's no way life could replicate fast enough there to beat the turnover rate, even if you could have life in a carbon rich, hydrogen poor environment.

Yes, but even if we go before the heavy bombardment, it was still not an long time. Note that you need pretty tough bacteria like life to survive beeing thrown out into space, the first life must had been far more primitive.

I agree that mars is probably dead, decent chance for Europa or other ice moons with tides, depending on if they get pretty stable volcanoes.

[Aethon]

http://www.astrobio.net/news-exclusive/life-tricky-often-confusing-question/

One of the reasons we have trouble finding life elsewhere in the universe, is that we don't have a workable definition of what makes something alive. Definitions give specific meaning to terms by analyzing concepts we already understand. Our situation is analogous to that of the natural philosophers who tried to describe the 'nature' of water before the structure of the atom was understood.

Now we describe water as two hydrogen atoms bound to an oxygen atom, but before molecular theory was developed, it was difficult to understand what water was. It's wet, colorless, odorless, and thirst quenching, but other substances have similar properties. Alcohol, petrol, heck 64 oz of anything will quench your thirst- like fabric softener.

Once we had a workable atomic theory, the definition of water became simple- H2O. Until we have similar advances in the biological sciences that can give us a broad, theoretical scientific definition of life and how it behaves in a variety of chemical and physical circumstances, we are left with primitive speculation about lifes' fundamental nature.

Edited September 19, 2014 by Aethon

[KerikBalm]

One of the reasons we have trouble finding life elsewhere in the universe, is that we don't have a workable definition of what makes something alive.

Not true.

Our situation is analogous to that of the natural philosophers who tried to describe the 'nature' of water before the structure of the atom was understood.

Misleading, the structure of life on Earth, is very well understood (of course, it could be understood even better, but so could atoms...).

Once we had a workable atomic theory, the definition of water became simple- H2O

Yes, and what about all the other compounds. It was a long way from the structure of water to getting buckyballs, and we still don't fully understand stability of elements (still searching for islands of stability, superheavy stable elements).

Water is a particular kind of polar liquid solvent. Its not the only kind.

If there is life of the same origin as that on Earth, on Europa, or Mars, or Titan, we know what to look for.

Looking for other life, would be like looking for other compounds that are not water, but have similar properties to water, except a whole lot more complicated.

We can even try to predict what sort of life would be on titan if it lived in the hydrocarbon lakes, rather than the subsurface ocean. We can define possible energy sources and metabolic proceses, and predict what you'd need if the solvent was non polar.

http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Methane_and_other_hydrocarbons

[magnemoe]

http://www.astrobio.net/news-exclusive/life-tricky-often-confusing-question/

One of the reasons we have trouble finding life elsewhere in the universe, is that we don't have a workable definition of what makes something alive. Definitions give specific meaning to terms by analyzing concepts we already understand. Our situation is analogous to that of the natural philosophers who tried to describe the 'nature' of water before the structure of the atom was understood.

Now we describe water as two hydrogen atoms bound to an oxygen atom, but before molecular theory was developed, it was difficult to understand what water was. It's wet, colorless, odorless, and thirst quenching, but other substances have similar properties. Alcohol, petrol, heck 64 oz of anything will quench you thirst- like fabric softener.

Once we had a workable atomic theory, the definition of water became simple- H2O. Until we have similar advances in the biological sciences that can give us a broad, theoretical scientific definition of life and how it behaves in a variety of chemical and physical circumstances, we are left with primitive speculation about lifes' fundamental nature.

This only become an issue some settings: Mars or other inhospitable places where life is not only very rare but also probably is very alien.

You will not notice this from orbit, not to talk about interstellar distances anyway, you can detect O2 with an good enough telescope and this proves life.

If you don't find any interesting in the atmosphere you will get problem getting funding for the starship making an in depth investigation hard.

Intelligence is much similar however here you are more likely to run into borderline situations. In many settings it would be obvious, yes you can have some decent sized animal who behaves like social insects, they could organize on large scale and build impressive structures. (probably less likely than intelligence, as evolution run far slower in large longer lived animals than insects.)

You can have borderline issues, even if intelligent they might not use tools at least not much, add that hunter gatherers are rare and might be hard to spot. More fun if they only live in jungles.

[Aethon]

Not true.

Ummm. Care to elaborate, or define life for us all?

[nuclearping]

the sooner you realize that, the sooner we can have an intelligent conversation

The "intelligent conversation" thingy is getting odd at that point when you claim to know more than the other person, about things which are complete speculation and theory.

Even here on Earth it is not clear how, when and where life began. And furthermore not even how it was able to evolve in that short period of time given the numerous mass extinctions.

Also latest conclusions and theorys say that chances are high that either the basic components of life OR even more complex life already in forms of amoebas or bacteria have been brought by asteroids.

And so we are (finally) back at the original topic: If life was brought to Earth by Asteroids, then chances are high that this has happened somewhere else too.

He didn't draw conclusions, he criticized your logic.

Whoever you refer to with "he", "criticizing logic" doesn't mean "he" is more right. As I said above, we are speaking about subjects which are just pure speculation and theory.

Also, you should google Russel's teapot.

I don't understand what "Russel's teapot" has to do with this. Thats nothing about Religion. And it is not a debate about who is right and who is wrong. Because thats not the right thread for that. You do realize that this thread was started by the OP inviting us to share ideas, thoughts and insights, right? The thread was not started to pick someone's ideas and disprove it. Or to find out who's ideas are "nonsense".

Honestly mate, don't try so hard dragging this down to a personal level. If you can't stand my ideas and thoughts then this might not be the thread for you.

If you think you are right and I am wrong, thats fine. I can leave you there. But stop trying something here. I don't need you to "save" me from my delusions or "hell" or whatever you're thinking.