Statement 1 is absolutely true. There are hundreds of billions of stars in our galaxy alone. Statement 2 is highly probable, seeing as how even with our limited ability to see exo-planets we’ve found several plants similar to Earth already…and we’ve only been able to see a couple hundred planets outside of our solar system so far. There will be trillions of planets in our galaxy alone.
Statement 3 and 4 are the most speculative, but even there it’s not like they are just pulling that out of their ass or making it up out of whole cloth. Even at 1 in a billion for possible life and 1 in a billion from there for possible advanced civilization there would be a couple in our galaxy alone. Now, whether we could or would ever hear from them…THAT’S improbable for sure.
Expanding into space is more that being just about breathing room, it is about resources.
The reason that there are ghost towns in the western US is because there used to be a mine or other resource there.
That resource has been consumed. That is why people will not move back there.
We will before too long (within thousands or at least tens of thousands of years), exhaust all of the extractable minerals in the crust, and will have extracted all the easily accessible ones long before that.
If we have not at that point started a supply line of resources coming from off planet, then we will end up with the same fate as Easter Island.
To that end, I would actually expect our first contact with another civilization to take place either by their mining equipment riding into the solar system and starting to tear things up, or when our mining equipment starts sending back some interesting organics from a distant star.
We may have already noticed analien civ, but that is a long way from actually communicating with them.
And of course, if an extraterrestrial race picks up our signal at N light years away, it would take another N light years for their response to get back to us. So even if those first radio broadcasts were strong enough to be distinguishable from background noise at 50 light years, there would have to be someone within 50 light years of us to pick up our signals during this past century.
But like you say, the bubble’s in all likelihood way smaller than that, because our early signals would only be distinguishable for a few light years out, so that would cut into the time that stronger signals would have had to get out there and get a reply back. If (for instance) we only started sending signals out 70 years ago that could be read tens of light years away, then the bubble for being heard and a reply being sent already has a radius of 35 years. And the smaller the bubble, the fewer stars, and the fewer hospitable planets, no matter what the ETs’ body chemistry is like.
I expect to live another 30+ years, but I’m not expecting that we’ll hear from our interstellar neighbors before I shuffle off this mortal coil.
Gotta start somewhere. That estimate is as good as any, unless you have better?
In fact, we do have better. We know that life started on earth within a very short time ( and possibly even before) of the crust solidifying.
Obviously, we are still only one out of one, so it is hard to do any sort of statistical analysis, but the fact that life got a hold that early indicates that it is something that will likely emerge rather quickly and reliably whenever the conditions are correct for it, so I would really estimate that number to be much much higher.
Finding signs of life on the other solar system planets will give us a much better idea as to what the likely hood here is.
Now, after that, evolving into tool users who may go out into the stars, that’s a much harder stat to come up with. We don’t even know if our data point is a 1 out of 1 or a 0 out of 1 at this time.
Figure the majority of the time, life on earth consisted of single cells, and even after multi-cellular life, nothing was really all the complicated for most of that era either. It is only when we get into the latest eras that things start to get interesting, and there are creatures that could potentially have the ability to become intelligent tool users. Grasses, a pretty important part of agriculture, didn’t evolve until the last 100 million or so years, so any species that evolved before that would not have had any of our staples we used in our agricultural revolution.
Humans only take up a tiny sliver at the end of history, and our radio communications and space travel take up an even tinier sliver of even that.
Well the Universe could be, in the abstract at least…teeming with life. If life arose on only one planet in every millionth galaxy that would still mean there are (or have been or will be) 2 million life bearing planets out there.
And there’s the problem. Alien life could be an almost nailed on certainty within any given galaxy and still be so scarce and distant as to make overlapping timelines extremely unlikely and actual contact or communication even more so.
For life? Seems reasonable to me (actually, seems way conservative for just life, since there are some indications based on extremophiles on Earth that life has a larger range than we thought)…and life stared on the Earth much earlier than originally thought as well (and might have started even earlier and been wiped out when a Mars sized object hit the planet and formed the moon). Personally, I expect to see some indications non-Earth based life in our own solar system in my lifetime, which will pretty much indicate that instead of 1 in a billion for life it’s much more common.
As for advanced civilizations, that’s much more speculative obviously. However you want to quantify that it’s going to be pure speculation, since even on our one example of a planet with life on it we know of only one species that has an advanced civilization…and that one only because of some extraordinary luck and circumstances with a very long interglacial period. But 1 in a billion for life and of those 1 in a billion for advanced civilization seems like a good bet…and even if we assume 1 in a trillion there could be a few other civilizations out there, somewhere. We’ll probably never know, but I don’t think it’s totally off the wall.
I regretted saying it that way after I posted, but it was too late to edit. That’s not the word I wanted to use, but at the moment I just can’t think of a better one. Just “different” might be what I’m after. What I’m really looking for is a way to cool the flames next time I get in a discussion about this. I figure that if I could input a lot of possible reasons, then it wouldn’t divert into a discussion about Roswell or Area 51 and/or that the government must be concealing the truth from us. I’ve had this conversation many times with intelligent, well-educated people, and the ones who really, really want there to be sentient extraterrestrials, the ones who get really bent out of shape during these discussions, will frequently offer up this explanation out of what I suspect is desperation to explain it. I agree with you that the reason why there is no hard evidence of this type of life form is very likely to be a simple and straightforward one. But if I had the ability to input 10 or 15 reasons instead of just 3 or 4, then these people would calm down and look at it more critically.
There are so many great stories that can be (and have been) told involving contact with aliens, that it’s very common in science fiction—which tricks us into thinking it’s more plausible in reality than it actually is.
One “out there” thought … if the aliens do get here, they may well be very low on fuel, water, spare parts … and food … when Columbus first landed in America, my understanding is he and his crew were in dire straits … let’s hope these aliens spiral their proteins opposite of us …
I think it’s a combination of sentient life being exceedingly rare, able to tool-bear and getting past extinction level events whether natural or self-created*…or we’re in a sim. Stuff like that.
*And who knows, maybe theres’s some nearly unavoidable techno-event as yet undiscovered like “null-energy explosions”
No; that’s totally incorrect. Go ahead and name even one “assumption” in the Drake Equation. There aren’t any.
If you must criticize the Drake Equation, it would be because it is tautologous. It is absolutely true, but it doesn’t really tell us the answer.
(as a comparison: I want to know how many men named “Smith” there are. First, find out how many people there are. Multiply that by the proportion of people who are men. Multiply that by the proportion of people named “Smith.” You get the correct answer, and no assumptions have been made.)
It took us 3.5 billion years to evolve from single-celled balls of not much to the all-singing, all-dancing miracles of evolution that we are today. Now, thanks in no small part to technology, we are evolving - in the broader sense of the word - at an exponential rate. The fusion of technology and biology is already happening (albeit in quaint, inefficient and clunky ways - think Google glass…) - and we now have access to far more information literally at our fingertips than folks would have imagined even a few decades ago.
Let’s add another 3 billion years of (exponential) technological progress, and assume (ahem) that nothing cataclysmic happens to our civilisation/planet in that time.
What would we be like? I’m guessing not even recognisably human. We probably aren’t even be able to comprehend what sort of being we would be (much like our 3.5 billion year ancestors wouldn’t recognise us). ‘God-like’ would probably be as close as we would get to describing it - some kind of omniscient, omnipotent being (certainly as far as our 21st-century monkey-brains are concerned). Problems like overcoming the speed of light will no doubt appear as primitive and childish to them as figuring out longitudinal navigation does to us. If that might be us in 3 billion years, then it stands to reason that someone else out there in the universe has already gotten there in terms of technological progress. Space is big, after all, and it *has *been around for a long time.
I think we are thinking too much in the box in assuming that technologically superior aliens will come rattling along in UFOs; really advanced beings wouldn’t have the need to ‘travel’ at all. Perhaps those guys are, literally, everywhere - having completely transcended the dimensional limitations that we view as absolute.
Our radio emissions (including television transmission) obviously have a maximum radius of less than 120 light years, but even with that most of the signals are not going to be distinguishable from the background radio environment without extreme amplification at that range which would necessitate already looking for and knowing the format of the signal. Ditto for the converse; the maximum range at which we could detect an emission radiating omnidirectionally at terrestrial power levels is probably less than the distance to the next star, and even for signals intentionally directed at Sol using a transmitter as powerful as the BMEWS early warning detection system would be somewhere on the order of 100 light years at best. That’s only about 500 stars in our sparse local neighborhood out of an estimated 100 billion stars in the galaxy (although most are awash with levels of radiation that would be lethal to any organism based on organic chemistry), and only 28 of those are G-type stars, so the odds don’t even favor being able to talk to any extant alien species. See [THREAD=764192]“How far in space can we detect our most powerful radio signals?”[/THREAD] for more details.
The idea that an alien species may be trying to contact us in ways that we cannot even detect is entirely plausible; genuinely long range transmission would almost certainly eschew electromagnetic radiation (which can be occluded by dust and radiating material) and use coherent gravity waves. We are, of course, just recently and barely able to even detect gravity waves and could probably not detect discrete sources that were of less than large black hole size. Or they could be transmitting by some other means that is so completely beyond our comprehension of physics that we can’t even imagine how it might work.
We cannot dismiss this possibility out of hand, but there is another, even more likely possibility; that out of the hundreds of billions of stars in our galaxy, about ten percent of which are potentially capable of supporting something like terrestrial conditions that would give rise to chemical life as we might recognize it, we might be very late to the game, and other intelligent species have arisen are are as far beyond us in intellectual capacity as we are to ants, and thus, we are not even worth contacting any more than you would attempt to converse with an ant colony, or so fundamentally different in outlook that it would like playing chess with an octopus.
Or alien civilizations may have arisen, gone through cycles of development and advancement, and have extinguished, either through conflict, depletion of resources, or have been overcome by some natural or manufactured disaster. Life has been around on Earth for ~4.2 Byr, complex (multicellular) for 1.5 Byr, terrestrial mobility for about 350 Myr, and anatomically modern humans for about 200 kyr. That is the metaphorical blink of an eye on the cosmic time scale, and there is plenty of times for a human-like civilization to have risen and fallen many times in that interval, perhaps never having attempted to convey their existance, or having shouted into the void with unheard invitations to respond. Unlike Star Trek, in which many independent civilizations have risen to comparable technological parity in the narrow span of a few hundred years, it is almost assured that there would be enormous differences in the technological ability to master energy production, utilize propulsion, and an understanding of basic physics, just as modern society would enjoy vast superiority and difference from ancestral hunter-gatherers of the Serengeti plains, Roman senators, or even Dutch tulip farmers from a few centuries ago. There is no reason to expect that any civilization that developed independently on its own timeframe will have any degree of parity without ours, or even share common views or interests, much less enough language to be of use for all but the most facile communication even if they have enjoyed parallel development.
Aliens will be truly alien; not like bumpy-headed extras exhibiting some exaggerated human characteristic like “pure logic” or “animalistic anger”, but with an approach to the world formed by their particular evolution, chemistry, and language (or whatever passes for it). We cannot expect that they have any interest in “talking” to us, or that we will necessarily understand what they have to say even if they do.
My point was that entering any real number into any part of the Drake equation is making an unfounded assumption. A guess. Wishful thinking. None of these variables are known.
But still this is used to show that there must be millions of technological civilizations out there.
I really think it’s just too early to tell. All we know is life can develop a heck of an imagination, but we still haven’t proven that imagination can lead to a viable civilization that can last millions of years, which is probably what it will take to run into our fellow galactians.