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Forum » SpaceEngine » Off-topic Discussions » Life in the Universe (Any and all hypothetical discussions about life elsewhere)
Life in the Universe
HarbingerDawnDate: Friday, 14.12.2012, 17:26 | Message # 61
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I think the most likely explanation for the Fermi Paradox is that intelligence is very unlikely to evolve.

I strongly agree with this (I'm sure I've ranted about this on the forum somewhere before). It seems to me that life in some form is quite common, but that complex life is relatively uncommon, and intelligence is rare, and for intelligence to occupy the type of body that can manipulate its environment and which actually develops technology and civilization is probably at best a once per galaxy per thousand years occurrence.





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apenpaapDate: Friday, 14.12.2012, 18:30 | Message # 62
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Before XX century nobody thought that flying would have been physically possible, today thousands of planes take off every day smile


Actually, people knew since the eighteenth century flying was possible, thanks to hot-air balloons. Even before that, the possibility of a flying machine had been around since at least the fifteenth century. In fact, I've even read about a Moon program based on winged ships propelled by gunpowder from the seventeenth century (though I haven't been able to find much information on that since, so it might just be something silly I read). Birds demonstrated every day flight was possible. There never was as clear a law of physics prohibiting human flight. Special Relativity on the other hand prohibits FTL travel, and not just as some obscure law somewhere, but as a logical conclusion from the observation that light speed is a constant.

However, I think light speed is unbeatable for a reason that actually has relatively little to do with relativity: it's a matter of simple resources. Try to calculate how much fuel would be needed to accelerate, say, the ISS, to a hundredth of light speed, travel to Alpha Centauri in 450 years, and slow down enough to enter orbit of a more hospitable sister of Alpha Centauri Bb (Provided it even has one; there's a good chance we'll have to undertake the 2000 year journey to Gliese 581 instead). But don't forget you need to accellerate the fuel needed to slow down at the end as well. Of course, the ISS isn't remotely suitable for a 450 year journey; you need something way bigger, the size of a city with as many people. I'll assume there's no need to bring extensive supplies of food, water, or oxygen due to a very good recycling system, but you'll need energy in any case, as there will be no stars near enough for Solar energy for the bulk of the voyage. So we've got this huge floating city with all that's needed to sustain it, and all this mass is not going to help get to Alpha Centauri; there's more fuel needed for that. At some point, you've basically got a mid-sized moon's mass of fuel, even really efficient fuel. And that's just to get to a hundredth of light speed; going at speeds where relativistic effects play a serious role probably requires entire planets worth of fuel. Even if there was no such thing as relativity and you could go as fast as you wanted, going faster than light would be almost as impossible as it is in reality.





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HarbingerDawnDate: Friday, 14.12.2012, 19:28 | Message # 63
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Special Relativity on the other hand prohibits FTL travel, and not just as some obscure law somewhere, but as a logical conclusion from the observation that light speed is a constant.

It prohibits "true" FTL travel, but it does not prohibit effective FTL travel through the use of technologies like warp drives (which we now know are not only theoretically possible, but likely feasible as well). So FTL travel may not only be possible, but might also be relatively simple (compared to the magnitude of the problem).





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horatiobDate: Sunday, 06.01.2013, 15:29 | Message # 64
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Some thoughts from me on this topic and the drake equation: I highly doubt that pure intelligence is enough to be able to reach FTL travel (like with a warp drive) or to be able to communicate with extraterrestrials.

If technology advances with the help of using intelligence, people become able to control more and more energy. This is fine since a warp drive or communication with extraterrestrials requires exactly this. However, the more energy one single individuum can release, the more damage can be caused by misuse. By the time a warp drive would be financially and technologically achievable mankind will already have destroyed themselfes. This is because for this to happen it would be enough that one single guy out of 10 billion people has a bad day and decides to create whatever kind of mass/gravity and thats it.

So I'd add even another factor to the drake equation: This one says how likely it is that a intelligent species has a sufficient social and ecological understanding of dealing sustainable with the things it invents.

I fear, our race does not meet these requirements.
 
TimDate: Sunday, 06.01.2013, 17:13 | Message # 65
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I tend to agree only with a few arguments of the Fermiparadox.
I am a 100% sure that there is more life in the universe, since the laws of nature are the same in the entire universe and it is through these laws that we came to be.
I do believe that it is extremely rare, I even doubt there is another life-holding planet in the Milky Way.
Too much, do researchers compare planets with area's on Earth where life can survive. Even though life must indeed survive, it seems to be highly adaptable. The question however, is not just where life can survive, but where it can begin.
The Drake equation could be a good meusurement if we had enough information. But right now we don't have a single clue on the chance that life comes to be or the chance that it evolves into a civilization. In fact, as far as we know, every planet with life evolves in a civilization.

Then again, I also have a few argument that I only thought of much later. Many things that we (or at least many of us) consider necessary for life are in fact just benificial to us because we adapted towards them. I don't think a moon is required for life to exist, maybe it was on Earth, but not every habitable planet needs a moon. Does all life really need oxygen and water? We don't actually know for alien life. And yes our system is rich of planets and we have a giant planet that adsorbs asteroids for us, but these asteroids are only disturbing for life, it's not necessarily for life to evolve with frequent asteroid impacts.
But most of all, Darwins idea of survival of the fittest does not only apply on life, it applies on everything that is. Life, a strange twist of nature is successful because it has the tendency to spread and survive. When you think about that it is in fact very logical that life is here, as the other chemical beings that did not have tendency to spread and survive got extinct.
With that logic, the universe should be full of life.
 
HarbingerDawnDate: Sunday, 06.01.2013, 17:14 | Message # 66
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So I'd add even another factor to the drake equation: This one says how likely it is that a intelligent species has a sufficient social and ecological understanding of dealing sustainable with the things it invents.

This is one of the questions that is implicit in the final piece of the Drake equation (the part dealing with how long technical civilizations live on a planet). Each part of the Drake equation has many factors/questions in it that must be answered to get a number for that piece of the equation. So your factor, while certainly important to consider, does not need to be added because it is already included.





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Edited by HarbingerDawn - Sunday, 06.01.2013, 17:45
 
HarbingerDawnDate: Sunday, 06.01.2013, 17:20 | Message # 67
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Tim, I have previously addressed many of the points you made here and here (obviously I have too much to say on the matter to bother trying to say it all again, hence the links).




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Edited by HarbingerDawn - Sunday, 06.01.2013, 17:45
 
horatiobDate: Sunday, 06.01.2013, 18:54 | Message # 68
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This is one of the questions that is implicit in the final piece of the Drake equation (the part dealing with how long technical civilizations live on a planet). Each part of the Drake equation has many factors/questions in it that must be answered to get a number for that piece of the equation. So your factor, while certainly important to consider, does not need to be added because it is already included.


Ah of course you're right. I missed out on that one. Thanks smile
 
WatsisnameDate: Sunday, 06.01.2013, 23:18 | Message # 69
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I am a 100% sure that there is more life in the universe

One can't be 100% sure until such time that we discover it. Until then the best you can do is be 99.999etc% sure. wink
I completely agree with you though; the development of life appears to be a natural consequence of the dynamics of the universe, and in my opinion, discovering that there is no other life in the universe would be far more extraordinary than finding that there is life elsewhere.

I do believe that it is extremely rare, I even doubt there is another life-holding planet in the Milky Way.

I think life is much more common than this; perhaps as much as 1 or more inhabited worlds per star system at some point in its history [on average], though I believe intelligent life may indeed be that rare.

I don't think a moon is required for life to exist, maybe it was on Earth, but not every habitable planet needs a moon.

I agree; life seems to be hardy enough to be able to develop and survive without a moon. I'm also not convinced the presence of a moon matters all that much anyway, aside from possibly moderating the climate via Earth's axial tilt. But even then, climate shifts and other extreme events actually appear to increase the diversity of life in Earth history, at least after the period of mass extinction has ended. I don't think anyone can say with authority how life would or would not have developed on Earth if there was no moon.

Does all life really need oxygen and water?

Oxygen? Nope. smile Many bacteria and archaea don't need oxygen. Oxygen did not even exist in appreciable abundance in Earth's atmosphere until less than 3 billion years ago, well after life got underway. There is even a report of a multicellular animal species Loricifera Spinoloricus which lives in the complete absence of oxygen.

Water on the other hand appears to be a requirement for all life on earth. Given its unique physical properties, temperature range at which it is liquid, and commonality in the universe, I imagine most life in the universe requires it as well. I don't argue that there may not be exotic life somewhere that lives entirely without water, but it's hard to imagine.

And yes our system is rich of planets and we have a giant planet that adsorbs asteroids for us, but these asteroids are only disturbing for life, it's not necessarily for life to evolve with frequent asteroid impacts.

A planet will get hit by asteroids regardless of the presence of giant planets in the system -- solar systems are inherently busy and chaotic places and are full of debris from their formation. As Harb as stated elsewhere, the migration of gas giants in the early formative phases of a solar system actually increases the cratering rate [see Late Heavy Bombardment].
Furthermore, comets and asteroids appear to have been a major source of both water and organic compounds for the early earth. (About half of the Earth's water seems to have come from comets, judging by the D/H ratio; and both comets and asteroids are observed to contain an assortment of organics).

Lastly, impacts actually aren't actually all that disruptive to life in the grand scheme of things, and there have been far more severe mass extinction events in earth history that had nothing to do with impacts. (Eg: The end-Permian mass extinction). Impacts simply don't do all that much damage unless they are REALLY big. It is of course a lousy time to be alive during or immediately after an impact, and there is a lot of diversity loss, but in the long run life tends to rebound with great vigor, often with even faster increase in diversity than before the event.

Sorry for the long post, I just find these to be interesting topics. smile





 
HarbingerDawnDate: Monday, 07.01.2013, 03:30 | Message # 70
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Sorry for the long post, I just find these to be interesting topics.

As do I. In my opinion discussion of this sort has been really lacking on this forum in recent months, and I would be happy to see topics like these resurrected.





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Edited by HarbingerDawn - Monday, 07.01.2013, 05:42
 
FastFourierTransformDate: Friday, 28.02.2014, 19:55 | Message # 71
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I'm one of those that thinks life is extraordinarily exotic and because of that, something extremely improbable. I have oscillated between the idea of existence and non-existence of extraterrestrial life from years but now I am pretty sure there's not such thing as life beyond Earth. I think it's normal to think otherwise because of many inspiring dreams and because of the confusion caused by our own existence (anthropic principle) in this universe.

ET supporters always argue by the fact that there are countless worlds. Yes, there are 400'000'000'000 stars in the galaxy, with at least 1.6 planets per star, with at least 2 moons per planet, in a universe with a trillion stars. There are something like 10^24 worlds in the universe so there MUST be life in some of them. But I think the probability of life is a number way much spectacular than 10^24. I think there are mechanisms that can explain abiogenesis perfectly and can do it more or less normal, but it continuous to be deeper than 1/10^24. Maybe it's normal for a universe to have one planet with life or two, but no more, and maybe ours has only one, the earth.

We are searching for life in places that look similar to our planet because we think that in those places there is more probability. But there is a perfect place for this search; the Earth. In the billions of years, since planet earth has formed, life has only appeared once and only once. The conditions are perfect for life but all life on earth comes from a last universal common ancestor. Life have began only one time. So why we think is such a normal process to happen in the universe?

Perhaps we are alone. And that is truly amazing!!!! cry

This is my firs post smile , I'm sorry for my english, it's not very good


Edited by FastFourierTransform - Friday, 28.02.2014, 20:02
 
midtskogenDate: Friday, 28.02.2014, 22:12 | Message # 72
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Quote FastFourierTransform ()
We are searching for life in places that look similar to our planet because we think that in those places there is more probability.

Perhaps not so much for probability of life, more for probability that we would recognise life.





NIL DIFFICILE VOLENTI
 
Destructor1701Date: Sunday, 02.03.2014, 05:28 | Message # 73
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Quote FastFourierTransform ()
We are searching for life in places that look similar to our planet because we think that in those places there is more probability. But there is a perfect place for this search; the Earth. In the billions of years, since planet earth has formed, life has only appeared once and only once.


As far as we currently know. I reckon that, were exotic life to spark in some pond somewhere, we'd have to be extremely lucky to have a biologist nearby to sample it out of pure random curiosity, before it is out-competed by pre-existing biological life for resources or space.

We have life on Earth dominating the biosphere, descending from one particular abiogenesis - maybe life got started multiple times, but this is the version that dominated.





 
FastFourierTransformDate: Sunday, 02.03.2014, 15:43 | Message # 74
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Quote Destructor1701 ()
We have life on Earth dominating the biosphere, descending from one particular abiogenesis - maybe life got started multiple times, but this is the version that dominated.


That's an interesting idea. Life as detroyer of posible independent forms of life. But we have to ask if is it possible that life on earth makes really impossible other new abiogenesis and why, even in lab controlled conditions, we haven't yet created life as we know it.

Maybe life is not so common in the Universe as we ussually think .
 
SalvoDate: Sunday, 02.03.2014, 16:01 | Message # 75
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Quote FastFourierTransform ()
That's an interesting idea.

I believe so too, my opinion is that processes like the "creation" of life, may require a smaller amount of time to be accomplished, than what we actually think, if Earth have life, right now, doen't mean that it started when we actually think it was, it may be started in past, destroyed, and started again.

For example, look at collisions, they can happen in any moment during the lifetime of a celestial object, and they happen when there are all the conditions for that to happen (in this case, when two objects are in the same place), if a planet do a collision, it may do another one in future, even 2 months after, and so on. If you are right there, watching the 2 planets colliding, you believe that it's the first time that it happens, but that's not always true.

Twisted reasoning wacko





The universe is not required to be in perfect harmony with human ambition.

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(still don't know why everyone is doing this...)


Edited by Salvo - Sunday, 02.03.2014, 16:05
 
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