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讨论规则及指引
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However, our estimation that contact is unlikely is us making projections based on our understanding of physics which is incomplete. As a species, we're not technologically matured enough to make an accurate projection about what is likely. We just know that things in space are so far away that we can barely comprehend the distances with no reasonable technologies available to close that distance with.
If we dig into taboo subjects, there are a large number of records published from numerous governments and credible witnesses that give some weight to the idea that advanced life forms are already visiting us. We've been trained through public ridicule to discount these thoughts, but if the evidence exists it should be considered seriously regardless of established bias.
Probably the coolest aspect of those reports is what people have predicted about the technical operations and design of the ships (if we play with the assumption they exist).
http://en.wikipedia.org/wiki/Declassification_of_UFO_documents
http://www.hyper.net/ufo/overview.html
http://www.hyper.net/ufo/physics.html
These kind of craft would require a pretty amazing energy source. We're only now making headway on more compact fusion reactor designs and even if they work, they may still be in their infancy for hundreds of years despite the aid of supercomputer simulations. Even then, these craft might be using an entirely different more advanced type of power source if we assume they travel large distances in space.
http://www.helionenergy.com/
http://www.lockheedmartin.com/us/products/compact-fusion.html
Unfortunately this all makes the ships in Starpoint Gemini 2 seem pretty unimpressive. :P
But the fact stays fact, that the Universe is mind-boggingly big: a 'normal size' galaxy, like that of ours, has about 100 to 400 billion stars, statistically at least two planets each, and there are about 100 billion Galaxies in the Universe:
A 2010 study by astronomers estimated that the observable Universe contains 300 sextillion (3×10^23) stars.
Now that number is BIG.
Where is at least ONE civilization that has already discovered some sort of interstellar, FTL travel method and has the capability to get about and about and say hello to their human brethren?
And here comes this Fermi-paradox, that explicitly states this fact by none other, than one of the biggest physicist minds in history, Enrico Fermi:
The basic points of the argument, made by physicists Enrico Fermi and Michael H. Hart, are:
- The Sun is a typical star, and relatively young. There are billions of stars in the galaxy that are billions of years older.
- Almost surely, some of these stars will have Earth-like planets.[2] Assuming the Earth is typical, some of these planets may develop intelligent life.
- Some of these civilizations may develop interstellar travel, a technology Earth is investigating even now (such as the 100 Year Starship).
- Even at the slow pace of currently envisioned interstellar travel, the galaxy can be completely colonized in a few tens of millions of years.
According to this line of thinking, the Earth should already have been colonized, or at least visited. But no convincing evidence of this exists. Furthermore, no confirmed signs of intelligence (see Empirical resolution attempts) elsewhere have yet been spotted in our galaxy or (to the extent it would be detectable) elsewhere in the observable universe. Hence Fermi's question, "Where is everybody?"Indeed, where the meep is everyone?
From time to time we have fundamental discoveries, that changes our view of our surroundings and helps to understand our world. Einstein is one classic in this field - among others, his notion of relativity led to the key of understanding how could the Universe be bigger than older:
it is estimated as 30 billion light years big and 13 billion years old.
If nothing can travel faster than the light, the Universe cannot stretch to cover a ground this distance when light itself could have only covered one-third of that distance since it exists.
There is an other, that led to the discovery of Big Bang - namely the cosmic microwave background (CMB). It made us understand that the Universe indeed started somewhere and has a history.
I could go into many details; why this Universe is suitable for life and why other possible universes are not, why physics is like what we know today, why parallel universes are not just a reality, but a must-have, I just simply do not have time to write about it.
Everything taken together lead to the conclusion: we should not be alone, millions upon millions of civilizations should roam the galaxies and we already should have a vast network out there.
But something seems to be wrong.
The article above has a very important notion: the Universe is hostile towards life. If you read it carefully, it implicit states that there are super-sized suns, and those literally sterilize sections of galaxies of any life from time to time. It is a big step forward in our understanding of what is wrong, why we have not been visited yet. Also a very big warning to eventually give up the fight over our little, petty, selfish differences and finally get together like a race and start building our future.
The vastness of the universe and the speed of light can all seem very small and slow once technology is advanced enough to close those gaps.
The speed of light is experienced partly as a function of time. That something cannot travel faster than the speed of light may also only be true within a context. Whether time travel is possible or not, it may be possible to compress time and abuse the fabric of space in such a way that travel is more like repositioning, however subtle the difference.
Let's assume that some advanced race wanted to survey the universe. Would they send out un-"manned" FTL drones that can visit all life-supporting planet candidates and report back to the point that they locate so many planets with various levels of intelligent life on them that we are almost uninteresting to them?
Would they have such advanced power sources that they can basically manufacture any matter they need, so the construction materials needed for these drones is infinite? With nearly unlimited "speed", unlimited power, no strain on natural resources... what would their perspective be after they've seen thousands of different civilizations? What would the motivation even be aside from finding other host planets after the lifetime of their star ends? If they have everything they need, should they interfere with other civilizations directly to help them along, or stay hands off?
I would say that no matter who our smartest physicists are today, we're barely at a point where we can make an educated guess. Once we've hit a technological ceiling where even with the power of supercomputers millions of times more advanced than our current machines and the most advanced power sources we could produce we cannot see the possibility for improvement, then we may be able to hazard an educated guess.
That said, if we do get visited or have already been visited and can prove it, then there is no need to guess.
What caught my attention in that article was that it explains clearly why life was impossible in the Universe. It shows that in the past, in every Galaxy there were a few super giant stars that sterilized sections of them in about every billion year or so: it hints that maybe one or more, hitherto unexplained extinction event here on Earth could be tied to this cosmological phenomena, so it must be considered as a really existing mechanism.
We are living in an 'old' Universe, our sun is a third generation star, a relatively young one. The mechanism mentioned in the article could well mean that every life form that tried to emerge before is reasonably extinct or never had the chance to get a foothold in the first place. It shows that when considering the possibility of life in the Universe we need to account not just how long it takes for life to develop intelligence, or what are the suitable settings for life (planet/star type, distance for the star, distance for the galactic core and such) but we have to look for potential hostile mechanisms in the heavens.
And exploding superstars, that irradiate half of galaxies in every couple of million years are definitely things that have the potential to keep the Universe sterile.
Going by that, we could well be the only species that managed to launch a rocket for the first time in our Galaxy. It is definitely a notion that shocked me, not because it is novel - it is not, but because it has a scientific backing. We have so much sci-fi garbage pouring on us for fifty years now, that it makes us believe the Universe is a populated space, but the reality could be that it is a lonely place indeed.
I think Occam's razor applies here: we have not been visited yet simply because there is no one out there who can visit us.
It simply could be, that the Universe is only now getting into the phase from where life is possible to sustain. There could be other civilizations parallel to us on their way in reaching the stars, and it is most likely that every species existing are far from achieving FTL and galactic empire, like us. So we could be in a good starting position here.
It is all academical: until we do not have the means to get to the stars and see them with our own eyes up close, you cannot be really sure. Or until a flying saucer pops down onto the Trafalgar-Square and little green men swarm out of it asking directions for the next free inter-species toilet facilities.
Nice reading such intelligent meepsters theorize on such a big subject. Read and enjoyed!
@ Crache > Check out "The Disclosure Project", if you're into UFO conspiracy-theories.
Extinction events don't necessarily kill all life on a planet, but things that live on the surface are least likely to survive. Depending on the strength, distance and duration of a GRB, various depths of the ocean are less effected and there may be varying levels of impact on the opposite side of the planet (atmospheric chaos, granted.)
Outside of the earlier chaotic life of the universe these only occur so often and we don't know for sure what the time variance is for intelligent life to evolve. This does make it hard to predict. Maybe we are really slow starters.
We could be the first to advance, but it could just as well be we're in a marathon with a bunch of others we can't see, so when we cross the finish line it's more satisfying to think we're the first. Scientific backing that intelligent life is hard is not overly strong evidence that intelligent things won't live. We're here. Even if we chop 90% of the universe out so that only the least turbulent areas exist, it's an unthinkably large amount of space. Even if we take that remaining 10% and take only the portion of it that represents what remains of the Milky Way, it is a lot of space.
Whether we have been visited is a variable we don't know, so making a solid claim based on it is tough. Many people are confident they have had experiences that they equate to evidence of visitation, but they are such amazing claims that we refuse to lend credibility to them for fear of being ridiculed even when there may be some remaining physical evidence of an occurrence of some sort.
If by "only now" you mean the past several billion years. :) I think that once a civilization becomes advanced enough, GRB events might no longer be a threat to their survival.
Surviving for hundreds of millions of years after you've mastered technology is hard to imagine, though. Inidividually, we tend to only think of our lifetimes. Historically, we know of all these events in the past and even though we didn't experience them, chains of individuals reproduced as time passed and here we are at the current iterations of that chain. What happens when the iteration frequency slows down, population is reduced and lifetimes are closer to immortality? Is insanity or other mental illness still an issue? It's really hard to think about what humans would be like even 1 million years from now, assuming we no longer depend on Earth for survival.
Do we come up with predictions that say if we have been visited by remnants of a 400 million+ year old civilization, they are simply automated AI left behind? Would a civilization like that send off populations to live on various host planets to optimize the long-term survival of their species? Would they live underground or under water to avoid GRB concerns?
It's really hard to say, but we don't know enough to suggest that an advanced civilization can't survive for hundreds of millions of years, because we're the only one we have experience with and we'd only consider calling ourselves advanced for a tiny fraction of our existence. Governments and world structure are still fluctuating, so we don't even know what the final format will be for the organization of humans after several iterations of genocide and war from now.
What you are looking for is http://en.wikipedia.org/wiki/Drake_equation
It's the sort of equation that can be neat with the correct inputs, but we have no idea what the correct inputs are, so it's not that useful. Once there's more information, then the results will get more interesting.
Like the wiki says, these parameters are hard to define, without having encountered said lifeforms first>
- the fraction of planets that could support life that actually develop life at some point
- the fraction of planets with life that actually go on to develop intelligent life (civilizations)
- the fraction of civilizations that develop a technology that releases detectable signs of their
existence into space
- the length of time for which such civilizations release detectable signals into space
But pretty interesting reading that nonetheless.