• Check out the relaunch of our general collection, with classic designs and new ones by our very own Pissog!

Extraterrestrial Life

It is perhaps not so outlandish to think there may be no life visible to us. Owing to the light speed limit, we can only have contact with a certain region of spacetime. The further out we look, the younger the Universe becomes.

For a planetary system to form (and certainly for terrestrial planets to form), there need to be sufficient heavy elements. These heavy elements are formed in previous generations of stars, and spread when they go supernova. The Sun is believed to be a third generation star - it's likely first and second generation stars could not have had planets. This thus may impose a minimum age after the start of the Universe for life to reasonably emerge, and consequently a somewhat smaller region of space than the entire observable Universe.

That said, there are many known extrasolar planets. Few are particularly earthlike, but that is simply because we cannot so easily detect small rocky planets compared to big gas giants. Life is known to have arose on Earth very early in its existence, which suggests it readily arises in a suitable environment. So for life to be rare, suitable environments would have to be rare. This is the factor we are really unsure of.

By contrast, intelligence took billions of years to arise (as far as we know - I'd have thought we'd have found traces of a previous intelligent species on Earth, but maybe we wouldn't). Thus, we could be the only intelligent species within our visible horizon. Supporting the plausibility of that is the consideration that someone has to be first. Even if intelligent species turn out to be a dime-a-dozen in the Universe in the next few billion years, there has to be a first one, and it will be alone. It could be us.
 
I think there are extraterrestrial lifeforms somewhere.
the universe is so big, and we havent seen much of it yet.
but what I do think is that there is a possibility there might be alien lifeforms that dont need all of the things we have here on earth.

normally im a bit sceptic though about some ufo movies, most of them are really crap :P

although I must say I laughed at http://www.youtube.com/watch?v=MdK2QCgBAdA XD
 
I do believe that there is live elsewhere in the universe. Be it on an earth-like planet, bacteria on a nonhuman-inhabbitable planet, or even life forms not based on carbon (silicon is a possibility), the possibilities are enormous, and I am sure that there is somewhere out there where one of the above 3 happens.

The question about intelligent life is a different one. I think it's pretty sure to rule out intelligent life in the solar system. But out there, we have just no way to know at the moment.
 
Hawking makes good points. The idea of uniformitarianism or at least assuming that they will be natured like us is pretty paranoid- the fact that we are violent has zero bearing on other animals, never mind extaterrestrials, natures or violence. The hype this article may cause is a little silly however- even if we did find aliens or they found us, it's pretty difficult to communicate. Hell, space travel is so impractical between planets for us, so going to habitable extrasolar system is pretty much out of the question. I think the best we can do is just to find extraterrestrial life and go "huh, cool". It's not even a question that there is life elsewhere in the universe- some of our extremeophiles here on Earth demonstrate that life is pervasive even in pretty outrageous (by our standards) conditions. It's just a question on the nature of the life, how practical it is to study or find it and where it is.

I agree that it's probably good not to show others where we are by carving maps into probes and purposefully beaming out messages to whoever would be listening. Our planet isn't exactly inconspicuous though...we are an exceptionally noisy planet and those noises are travelling from 20+ years ago (radio messages bounced into space, etc) and they aren't exactly going to stop. So in that regard, our fate is a little sealed already. At best though, it would show that we exist, not necessarily where we are. I think it's important to continue to look for other life. I agree that it's almost a certainty that intelligent life exists elsewhere or at the very least has existed in the past and that life in some form exists all over the damn place.
 
I think it's been reckoned that Earth is nearly as bright in radio waves as the Sun. So yeah, we'll kind of stand out to anything that can resolve the Sun and the Earth as two separate radio sources.
 
Look at universe's size. Do you really think we are really the only intelligent life there? :/
 
. I still don't think that it's enough of a fear for a person to convince themselves that life probably exists elsewhere in the universe, which is what I'm now taking his argument to be
Click to expand...

One of the greatest fears of people (even more than death) is being alone. This is because we are wired to be social. Therefore, people want to believe that there is life outside our planet. It's very similar to people wanting to believe that there is a God, or that there is a purpose in life.

In my opinion, to suggest that in the entire vastness of the universe, our planet is the only one capable of harbouring life is very arrogant. The prospect of extraterrestrial life is, in my opinion, almost certain.
Click to expand...

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
While I agree, there are theories that support the fact that we are, in fact, the only planet with life.

The idea of uniformitarianism or at least assuming that they will be natured like us is pretty paranoid- the fact that we are violent has zero bearing on other animals, never mind extaterrestrials, natures or violence.
Click to expand...

Thats exactly my point. It is very possible that the creatures that we may meet have no inclination to hurt us. It is also possible that they experience no (what we call) emotion whatsoever. The vast difference in cultures that will occur when life develops on another planet is simply inconceivable.
 
I think most of you are looking at this too mathematically. The general idea is that in a universe so big that has been around for 14billion (american billion) years surely, chance dictates, that there must be more life. IMO, something like this can't be looked at mathematically as we have no idea what the chances of life being formed are and the chances of planets having sustainable and suitable conditions and life apppearing on planets with those conditions and life not quickly becoming extinct and life evolving over time and gaining intelligence and so on and so on (so really I think the chances are stacked against it).

I'm sure there is some kind of physical theory which means there must be aliens but I forgot its name (something like equilibrium theory but not that) but it's just a theory and I have no idea about it just that it shows aliens must exist. TBH I think Biology and Chemistry would have a better chance at guessing whether there are aliens then maths or physics would.

But 94% (I think) of our universe we do not know about and personally I find Dark Energy much more interesting.
 
But 94% (I think) of our universe we do not know about
Click to expand...

I'm pretty sure its way more than that. We don't even have an answer as to how big the Universe is (it could be infinite)


http://en.wikipedia.org/wiki/Principle_of_mediocrity
Is that what you're looking for?

TBH I think Biology and Chemistry would have a better chance at guessing whether there are aliens then maths or physics would.
Click to expand...

All four of those fields would be used in such guessing. Physics, as well as Biology and Chemistry, would play a large part in determining whether or not a certain planet is habitable.
 
sce4 said:
IMO, something like this can't be looked at mathematically as we have no idea what the chances of life being formed are and the chances of planets having sustainable and suitable conditions and life apppearing on planets with those conditions and life not quickly becoming extinct and life evolving over time and gaining intelligence and so on and so on (so really I think the chances are stacked against it).


But 94% (I think) of our universe we do not know about and personally I find Dark Energy much more interesting.
Click to expand...

more like 100% of the universe...the amount we know is so tiny it's negligible in the grand scale.

The chances of life forming are pretty damn good, looking at the types of places life can be found. Hell, just the other day the first metazoan that lives in anoxic conditions was found.
 It's pretty well established that the scope of our life is small and the vastness of the universe provides opportunities for all kinds of environments. One thing that's pretty pervasive about life that we know is that it finds ways to take advantage of ANYTHING. Nucleic acid (both Ribo and Deoxy) are self assembling. Assuming Panspermia is correct, life would be pretty ubiquitous throughout the galaxy.

This absolutely can be looked at mathematically, but it's not like we have a formula and exact numbers. Think of it more like a lottery- if you have even really horrible odds (which we don't know if they are- they are actually likely rather favorable for the formation of life) and you have maybe thousands of planets, with virtually limitless 'tickets' per favorable planet to draw a win every milisecond (as the favorable ocean areas are rather large compared to the scale we're talking for life)...well just imagine for yourself. and we aren't even considering life as we don't know it or unfavorable places!
 
there probably is something out there, but like that british scientist said, it could spell the end of us so making contact with them might not be so great
 
I think sce4's 94% figure was to do with dark matter and dark energy, which we are reasonable confident exist but know very little about, and together account for about that much of the Universe's mass-energy.

In terms of complexity of structure, however, it's likely dark matter and energy account for a minority. Dark matter is supposed to feel nothing but gravity (and maybe the weak nuclear force), which is unlikely to be capable of creating the kind of complex life-conducive structures that normal matter readily forms under the influence of the electromagnetic and strong nuclear/'glue' force. Of course there might be an unknown force - 'dark matter' could turn out to be a whole 'shadow Universe', with complexity matching our own yet completely invisible by normal means. But that's wild speculation with no basis.
 
Kitten Bukkake said:
more like 100% of the universe...the amount we know is so tiny it's negligible in the grand scale.

The chances of life forming are pretty damn good, looking at the types of places life can be found. Hell, just the other day the first metazoan that lives in anoxic conditions was found.
It's pretty well established that the scope of our life is small and the vastness of the universe provides opportunities for all kinds of environments. One thing that's pretty pervasive about life that we know is that it finds ways to take advantage of ANYTHING. Nucleic acid (both Ribo and Deoxy) are self assembling. Assuming Panspermia is correct, life would be pretty ubiquitous throughout the galaxy.

This absolutely can be looked at mathematically, but it's not like we have a formula and exact numbers. Think of it more like a lottery- if you have even really horrible odds (which we don't know if they are- they are actually likely rather favorable for the formation of life) and you have maybe thousands of planets, with virtually limitless 'tickets' per favorable planet to draw a win every milisecond (as the favorable ocean areas are rather large compared to the scale we're talking for life)...well just imagine for yourself. and we aren't even considering life as we don't know it or unfavorable places!
Click to expand...

The main problem with this argument (especially with so many people in this thread arguing this same point) is that we don't know how life first originated on Earth. There is no way to be 100% sure of the conditions that our Early Earth hosted. Therefore, it is very difficult to imagine which planets life may and may not begin in. It is possible (although not probable) that Early Earth was much like Venus is today; hostile to life. Yet, somehow, life evolved from this place. This Earth-Venus analogy is extreme, but you get my point.
 
Panspermia suggests it may have formed elsewhere or multiple times in multiple places, just saying that there is an idea that life didn't start on Earth...still, the creation event had to happen somewhere. I think I pointed out in my first post that extremophiles are a pretty good indicator of what life WE know of can survive in. If they can live through that comfortably, perhaps other life can live through conditions we would consider extreme thusly raising the odds in favor of life forming all over the place.

The presence of life makes the earth more palatable to other life (and this works elsewhere, too). So just the presence of life means the situation drastically changes. the presence of extremophiles running rampant in your venus analogy actually means that it would transform proto Earth. BIF's show a good example of how this would work- the iron in the formations oxidizing because of increased oxygen (as the bed was being laid down) show how the presence of photosynthesizers actually make life better for those that enjoy Oxygen.
 
I pointed out in my first post that extremophiles are a pretty good indicator of what life WE know of can survive in.
Click to expand...

However, that is only the extent of survival on Earth. We have no indication if life can survive in conditions more extreme than those on Earth... this is especially important because most of the conditions in Outer Space are far more extreme than temperatures encountered on Earth.
 
The Stephen Hawking special on tv last night was pretty cool... I liked it because it thought a little bit more outside the box than those kinds of shows usually do. While there is definitely a lot of validity in the "evolution is the same everywhere" idea, leading to aliens that would look sort of like creatures on Earth, I also think at some point that the Universe is SO large and we know SO little about it or life that for all we know, extraterrestrial life could be something completely beyond the scope of our imagination... something we might not even recognize as life. I especially liked when he just threw out some examples like "a super hot life form that can only exist at the center of stars" (not an exact quote). As unlikely as that specific example may seem, it's still interesting to think that there could be life out there beyond anything we could ever think up.

I also liked the part at the end where he hypothesized that potentially the reason no alien culture has ever been able to reach us is because by the time any culture has developed the technology to travel through vast quantities of space, it will almost undoubtedly destroy itself through war or draining its planet of resources etc. I mean, even if it only took us 100 more years to develop interstellar travel, there's a chance we would destroy ourselves in a nuclear winter or something before we even got there... and what if it took 5000 more years to develop interstellar travel? ...I guess the premise is that intelligent life is ridiculously fragile, and what takes 2 billion years to evolve can completely destroy itself in the blink of an eye.
 
Yeah that part about them destroying themselves is totally speculative. I find it unreasonable to assert that the nature of alien life will be like ours simply because it's "all we know". It's entirely possible that something like a superorganism (like ants, as an example of that level of organisation) would develop a mindful collective intelligence- no violence against itself and capable of amazing feats. That's just a speculative example to offer up an alternative to Hawking's speculation.
 
Karen Carpenter is a stupid bitch then. To say anything for certain about life as we don't know it is pretty outrageous to begin with.
 
Kitten Bukkake said:
Assuming Panspermia is correct, life would be pretty ubiquitous throughout the galaxy.
Click to expand...
I disagree. If panspermia is relevant, life is likely to be RARE. Because we know panspermia is a long shot. A lifeform has to be blasted off one planet in a meteorite or comet impact, survive that impact and then a potentially very long journey through space, and survive another impact on landing. That's "hard" and thus unlikely - if it occurred in the Solar System then that suggests the arisal of life to be even less likely.

(Note that does not apply if life arose and thrives on comets - in that case one or zero impacts are needed, but it's unlikely lifeforms from one comet could reach more than one planet and also unlikely conditions are conducive to life arising there).

Also the Solar System is small and busy in astronomical terms, as well as being dominated by the Sun's gravity. Material ejected from one body will either find its own orbit somewhere or in due course impact another body. For something (other than a life-made spacecraft) to leave the inner Solar System altogether, travel tens or hundreds of light years, impact an extra solar planet, and life to survive that is unlikely in the extreme.

No, if life is prevalent in the Universe, it probably has to arise from non-life on almost every body it exists on.

About extremophiles - I believe there ARE places on Earth that are naturally sterile. Some parts of the Atacama desert have no detectable bacteria in the soil, because the area is absolutely dry.
 
How do we know Panspermia is a longshot? I'd say given the vast distance between planets or habitable bodies in the solar system, it'd likely be a saturation effect whereby you have more floating around than just a "rare" event. I don't really agree with Panspermia as a whole, by the way, I was just tossing it out there. It is possible for Amino Acids and etc to survive, so it is possible that some of the necessary blocks of life dropped in that way. Mind you, it'd have to have been after the Theia impact...well after. I agree that life probably just arose from non life many times over. I suspect that event is more common than we think. Hell, just look at the Ediacaran period of our own planets history- that could very well have been a separate radiation of life from what we are that was simply out competed. This has me wondering if there is a basic blueprint for life, something guided towards by the RNA/DNA (see the article I linked to in the last post). it's entirely possible that bacteria-like creatures are the lowest common denominator for all life across the cosmos. Since evolution is somewhat handcuffed by the ancestors own toolbox, it isn't unreasonable to assume that natural selection (which may have similar effects, at least predator/prey relationships) would lead things to be somewhat similar....bah, that's all just speculation, though speculation with a bit of thoughtfulness to it is always a fun thing.

Some places of the Atacama desert also have larger animals passing through or living and starch rich root bodies growing. Just a few months ago we thought metazoans ALWAYS needed oxygen. We also once thought arsenic was universally deadly or that sulphur wouldn't be a very good place to go making a living. Tardigrades, when encysting, can survive vacuum and near absolute zero conditions for weeks at a time. I agree that there are places where no life could exist permanently (or even pass through) I'm just thinking it would likely be best to keep an open mind about where to look.
 
I believe there ARE places on Earth that are naturally sterile. Some parts of the Atacama desert have no detectable bacteria in the soil, because the area is absolutely dry.
Click to expand...

There are some places there that havn't touched water in 12,000 years. I've been there, the air feels awful to breathe. Like sandpaper in your nose. Despite this, scientists have found microbial live thriving in the sand.
 
You must log in or register to reply here.
Back
Top