I would say the problem is that we have a very very rough estimate on the number of planets, and almost no idea what the probability for life is.
To be incredibly approximate, suppose there were 10^20 planets. What’s the chance of a planet supporting intellegent life? We know of one that does, and a few that can’t. This tells us very little.
What’s the chance of a planet being in the right temperature range? Of having the right chemicals? Of multicellular life developing?
If the odds of 10 questions like this were 1000 to 1, then the chance of inteligent life would be about 1 in 10^30. So it probably wouldn’t have happened.
Other guesses would make it certain there were millions of civilisations.
In short. We’re making guesses with frightening order of magnitude errors. No one has any idea how many planets have intellegent life. Neither guess is any better than the other, really.
You misunderstood my point. It is irrelevant what the actual probability is since the anthropic principle guarentees that there must be at least one sentient race in order to ask questions about sentience. Thus, if the probability was much, much lower than the number of stars in the universe, then it is quite likely that we are alone.
This is the best post so far. The likelihood that we are currently not alone in the universe is much higher than the likelihood that there was never and will never be other life in the universe. If there was other life somewhere in the universe in the past or there will be other life in the future, that doesn’t mean there has been other life at any time in human history or even the history of life on Earth.
Suppose a trillion civilizations, in the universe have each been expanding for an average of ten thousand years. Suppose these civilizations expand at the speed of light. Suppose further that this state of affairs is more or less constant, with new civilizations replacing fallen ones over the fifteen billion years of universal history. So, where are they?
Well, given that:
(1.5 x 10[sup]10[/sup])[sup]3[/sup], x 4/3 pi = 1.413 x 10[sup]31[/sup] cubic light years in the universal neighborhood.
And these trillion civilizations occupy
4.189 x 10[sup]24[/sup] cubic light years,
the percentage of space occupied by those civilizations is
0.00000296%
So that our nearest neighbor has the frontier of their sphere of influence about a quarter of a million light years from here. (plus or minis a hundred thousand light years.)
There is no paradox. We just live in a very large universe.
To draw from several posts and 2 threads, my comments:
This universe is lonely, and shall remain so, it is the nature of things.
The Universe is an elegy, our world will some day end, as will all things.
So the possibility of there being not only intelligent life in the Universe, but superior life to ourselves is incredibly high.
But it does not matter, as Tris pointed out, the possibility of us ever comming in contact with that life is extremely negligible.
We are doomed most likely, to spend the entire viable existance of our Universe, in our local star-neighborhood, floating around, keeping in touch through very long distance communication.
Or possibly, through Quantum Computers (I thought I originally thought of this but apparently scientists are already close to getting a working computer while it is all just still in my head).
Quantum Computers, or at least a quantum modem, can theoretically send transmissions instantly over any distance.
I don’t really have much hope that we will be able to go much farther as a species than a few thousand light years.
I don’t think this is correct. Quantum computers (if it is possible to build them) would be staggeringly powerful, but would still not allow you to communicate faster than light.
An interesting concept that noone here has touched on though is Von Neumann (ie self replicating) probes. If intelligent cultures are common then you’d think at least some would send out these probes to learn more about the universe around them. Given that they’re self replicating, it wouldn’t take that long (on galactic timescales) for them to reach every solar system out there at negligible cost to the originating civilisation. Yet we haven’t seen any. Maybe we will once we explore our solar system more, or maybe it means that there aren’t many intelligent cultures out there capable and willing to build them out there. Its purely a WAG, but an interesting one nonetheless.
Interesting. I always figured, based on our level of technology, that our most likely contact with an alien would be a robot slipping into orbit, taking some readings, and heading out. The roving, huge, and forested human habitat that travels light speed or interdimensionally is, um, some years away.
Your right, TBC could be thinking of quantum teleportation, but even that cannot communicate FTL. Quantum computers are slightly overated as it’s my understanding that they perform most calculations at the same speed as normal computers, there are a few calculations, such as the factorisation of a number into it’s prime factors which they can perform differently. Using this quantum method for smaller numbers actually takes longer than using the classical method, but for very large numbers the amount of time can be slashed by many orders.
A quantum computer is simply a computer that has 16(?) states instead of our present computers with 2. Its much more powerful (in theory, once they get the software to back it up), but has nothing to do with instantaneous transmissions. No idea what a quantum modem is…never heard of that term before.
The only thing that can do instantaneous transmissions over any distances is Black Crystal (from the Crystal Singer series :))…and we don’t have access to that unfortunately.
I assure you that modern compuetrs have more than 16 states!!!
In classical computing the most basic piece of information is a bit (the number of possible states = 2[sup]n[/sub] where n is the number of bits, for example a single letter of the English alphabet is about 4.7 bits of information and a computer that has 16 states could contain 4 bits of information) and this must either be in state 1 or 0, in quantum computing the basic piece of infromation is the qubit and this again has two states 1 and 0, but it can be in a superposition of these states.
From the time life started on this planet to the time that it will end, will be a tiny blip on the grand scale of time. Not only does one of these other cultures need to get sufficiently advanced, it also has to be sufficiently advanced at the same time as us. The two blips have to align perfectly. That significanly decreases the chances of us ever meeting space aliens.
I would guess that in the vastness of space and time there probably was a time or two when creatures from two different planets got to meet. They were lucky enough to be close enough to each other and exist at the same time. It doesn’t appear that we’ll be so fortunate.
Ah yes…Enders Game. How could I have forgotten??? We, unfortunately, don’t have one of these yet either. Honestly what I’d REALLY love for us to have is a nice Worm Hole Junction a la Basilisk Station.
Well MC Master of Ceremonies, I’ve only read a bit about quantum computers so I’m definitely out of it. I’m a network engineer so I don’t do much on the systems side. I thought there were 16 quantum states (for some reason that number was in my head) as opposed to our current systems with 2 states (classic binary computers)…on and off. As far as I know, quantum computers are still in the research and development stage, but it could have progressed beyond that for all I know…I haven’t really kept up on it to be honest.
One school of thought has it that we are in a priveiged period in cosmological history; the stars formedat the same time as our sun and the same approximate location in the galaxy will have the same metallicity;
very old stars will have low metallicity and few planets,
the planets that form around stars of the same age as the sun will be distributed in a similar pattern to those in our solar system, with smaller terrestrial planets in close orbit and gas giants outside,
while younger stars will have higher metallicity and will be more likely to have large gas giants near the central star, which have been dragged in by braking effects in the denser stellar nebula.
So we might be in a period when life of our kind is more likely than is has been in the past, and more likely than it will be later in the history of the universe.
I don’t absolutely agree with this idea (too many variables) but it is something to bear in mind.
I’m not sure I’ve got this right, but I think the idea is that in a classical computer each bit is 0 or 1, but in a quantum computer it can sort of be both. Which can sort of be represented as more bits, in some way (dependent on the total number of bits?). So for instance, in a classical computer, you could factor a large number X by putting a prime number in a word (a big byte), and seeing if it divides X. If it doesn’t you have to do it again. And again. And again. But in a quantum computer you can put all the bits in the word into ‘indeterminate’ state, divide X by that, and ONE state has divided cleanly, and you can somehow find which.
But I hope a quantum computer person’ll be along soon.
However, I’m fairly sure they have nothing to do with FTL.
[font size=1][sup]+[/sup]OSC credited ULG for iirc the idea and name of the ansible in the foreward to Ender’s Game. Though I think he said he might have removed this from later editions after learning the idea of FTL communication was too common to warrant it. I’m not sure. Still, Ender’s Game rocked, and is the main use of the ansible people remember. But ULG shouldn’t be forgot.[/font]
I can. Because as others point out, to assess to probability, you need to know the number of planets AND the probability of intelligent life arising on a given planet. It’s hard to say whether that probability is low or super-duper-low.
Let me propose an analogy. Let’s suppose somebody offered to sell you 450 billion lottery tickets. Each lottery ticket gives you a chance at winning $10,000. The price for the 450 billion lottery tickets – for all of them – is $150.00. Would you consider it prudent to buy them?
It seems to me that some fraction of your civilizations would likely expand for a lot more than 10,000 years. (Of course I’m just speculating here, but assuming that some percentage of these civilizations develop Von Neyman Machines, I think it’s reasonable.) The universe has been around for billions of years. I think that your calculation would yield a much bigger percentage of occupied space if we assume that some percentage of civilizations have been expanding for millions, hundreds of millions, or billions of years.
In addition to these crazy numbers you also need to add the number of planets revolving around all of these stars in all of these galaxies. The number is not known but the only one that we can accurately count has at least 9 of them here so I think it would be safe to factor in and at the very least double the amount of stars to get an extremely conservative number of the planets.
This by it’s self doesn’t prove a thing and that’s absolutely true. But what type of evidence to you point to in order to refute the possibility that intelligent life can be found throughout the endless universe. There are a lot of people that actually believe that we really are alone and they all seem to have come to this conclusion on blind faith alone. I just need to hear a single intelligent thought that supports the contrary.
Please enlighten me!!
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