How many technological civilizations do you estimate exist in the Milky Way galaxy? Assume the total includes the Earth.
[Define a “technological civilization” as one which can at least make simple machines a la the lever, wheel and axle, wedge, screw, etc. They do NOT have to have advanced tech, like rockets or radio, but may be presumed to soon have the capability.]
Wikipedia on the Rare Earth hypothesis, which contains an alternative formula with more factors (long story short they broke down many of the original Drake Equation factors into separate ones), tho I could not find an online calculator for it.
For the N’s which are less than one-you can interpret odds of e.g. 1/10 as representing 1 such civ within the nearest 10 galaxies (inclusive of the Milky Way).
Me, I think there might be one other within the closest 100 galaxies (so 1/100 civs in ours), if we are lucky. There appears to be a huge chain of unbroken causal events which must happen to lead to such a civilization, and I simply think that very few of even the suitable planets will ever develop one before something goes wrong on it.
If it’s one percent chance per galaxy, that gives us about 2 billion technology-using species in the universe. That’s probably better odds than I’d give, but that’s perfectly fine. Point is, with so many galaxies that each have billions to trillions of individual stars, the chance for something to happen once and only once ever has to be so mind-bogglingly low that it’s practically non-existant.
I had a go with the Drake Equation calculator and got 0.0005. I voted 1/10 but probably should have voted 1/1000.
I assumed a rate of star formation of 1 (as I have no idea what this is), half of all stars having planetary systems, one tenth of those having planets suitable for life, one tenth of those developing life, one per cent of those achieving intelligence, one per cent of those developing interstellar communications (personally I don’t think we’ve reached that point yet), and a thousand year lifespan for such communications.
I first made a fairly wild-ass guess of 10 civilizations, went to the on-line calculator and plugged in some numbers that I believed were reasonably sound but were themselves rather wild-ass guesses, then looked up 'rate of star formation 'and upon plugging in NASA’s value of 7, came up with 6.3 civilizations. So my first guess came as close as one could get with the poll choices, assuming the calculated values are realistic. So, er, I guess I’m pretty good at wild-ass guessing. Yay me.
According to one theory, gamma ray bursts were too common for meaningful life to evolve until 5 bya. Considering that life on earth is 4.1 billion years old (I believe they recently revised it and found life 4.1 billion years old had been found) maybe the universe is teeming with life, but maybe we are the most advanced right now (at least in this galaxy).
Do you mean milky way Galaxy or known universe? They’re two vastly different things, it’s a bigger difference than asking ‘how many people live in my house vs how many people live on Earth’.
Current evidence points to 1 technological civlization in the Milky Way, and I don’t think enough is known about the development of intelligent life to make a good estimate of how common it is. We don’t have detailed enough observations of anything further away to meaningfully talk about other galaxies. I suspect that intelligent life is not all that rare, but that the kind of technological life assumed in the Fermi Paradox (intelligent life that sets out to deliberately colonize every bit of space) is non-existent or vanishingly rare.
“Something to happen” being the spontaneous formation of life, and then for that life to evolve to a point of becoming intelligent, is something we have no frame of reference for whatsoever. It could very well be a 1 in 10^100^100^100 chance of happening at all, so for it to have even happened once is way beyond the realm of what’s expected, even in a universe as vast as ours.
I voted we’re the only ones because I just find it really wishful thinking to think otherwise. And if there were lots of technological civilizations, there would be some old enough that we’d be able to pick up radio signals from them. Yet people have been listening for over a hundred years since we discovered radio ourselves, and efforts like the SETI project have discovered nothing but dead silence.
I think it is highly probable that we are alone in the galaxy, and not just because we know that we are the result of a very long series improbable events which made our species possible.
Several years ago, an article in Scientific American dealt with the Fermi Paradox. When discussing the prospect of intelligence life in the galaxy, Enrico Fermi wondered “Where are they?” The authors of the article made some assumptions and concluded that a species which had reached our level of development would colonize the galaxy in ~ five million years, a blink of the cosmic eye. This seems reasonable. We will certainly explore the entire solar system within the next thousand years. How fast we go from there will demand new technology, but there is nothing in the laws of physics to prohibit interstellar travel.
So if this is true, and if intelligent life has evolved elsewhere, we should be able to detect it. There should be a lot of events which point to an artificial origin. When pulsars were first detected, it seemed that they were precise signals of intelligent origin, but alas, it was not to be.
We can be less confident in any conclusions regarding other galaxies, but if ours is typical, it looks pretty lonely out there.
We can turn this argument on its head and point out that we’ve been searching for signals on certain radio frequency bands for only less than a century. That means we’ve been more-or-less actively looking for signals for only 0.000005% of the time that complex life has existed on Earth. In that time, whole genera of life on Earth have risen and become extinct in repeated cycles. It is certainly enough time for an advanced species to evolve, rise to and beyond our equivalent level of technical accomplishment, and either become extinct (through natural or autogenous causes) or evolve onward to a level of technology and form we could not even imagine. And our ability to receive signals is quite limited to our very small and sparse pocket of local space within the galaxy; we ourselves could not transmit a measurable signal to a distance of more than a couple hundred light years using our most powerful transmitters (which happen to be ballistic missile detection systems), nor detect the errant transmissions of normal radio signals at the distance of anything more than the very nearest stars using our most sensitive receivers. We are quite literally deaf and dumb; there could be advanced civilizations zipping around the galaxy transmitting narrow focused radio, laser, or polarized gravity waves at each other and we would not be able to detect the slightest hint. We can’t assume anything about the purported “silence” other than we’re only capable of “listening” to errant signals in a relatively narrow band of the electromagnetic spectrum, where a truly advanced species may communicate via artificially generated gravity waves, quantum entanglement links, or some other mode of transmission that our very limited current understanding of physics hasn’t even revealed to us.
It is true that there are a large series of discrete thresholds we had to achieve in order to get to the state of cognitive and technological capability we currently enjoy, and that the probability of similar steps occurring in the same timeframe on another planet are quite small, but that’s hardly a persuasive argument against intelligent life arising; after all, there are literally an astronomical number of opportunities for this to occur, on the order of trillions of planets orbiting hundreds of billions of stars in our galaxy alone. Even if we assume that life could only arise under conditions somewhat similar to Earth, and that those conditions only occur in a fraction of a percent of planetary systems, we’d still be talking of tens or hundreds of millions of possible worlds where life could arise and evolve over the billions of years since Generation II stars expired and produced the heavier chemical elements. Given that our basic biology is constructed out of the most common elements in the universe and operates according to simple principles of organic chemistry using basic molecules that we’ve found in interplanetary space, it seems almost unlikely to the point of impossibility that life hasn’t spontaneously arisen elsewhere, and probably with great frequency.
The only way to avoid this conclusion is to assert that life has some special property, an “élan vital” that is beyond normal chemistry. Despite centuries of trying to discover this unique living energy, we’ve found that life on Earth actually has a very unremarkable set of basic elements and functions for regulation, signaling, energy storage and mediation, et cetera, all starting from relatively simple precursors and powered in common by a relatively simple organic enzyme and described in a simple four element code. We tend to think we’re pretty special but in fact the evidence is that we’re nothing very special at all in terms of our construction, and there is no reason a similar self-organizing collection of carbon-nitrogen molecules could not have formed and evolved into complex, self-regulating systems we would consider to be alive. And this is even without considering other chemical systems which could support complex organization. To be fair, the carbon-backbone molecules that we use are capable of far more variability and a good balance of stability and mutability than any other chemical system we know, so we would kind of expect any kind of life based on normal chemistry to use carbon in its basic construction, but even that may be too restrictive.
As for intelligent life, we have only the examples on this planet to look to, and species with complex connectomes (relative to the overall complexity of the body nervous system) represent only a tiny fraction of all life, but a critical look at the extant species shows complex organization in diverse species in many different phylum and orders which has the potential to evolve into the structures for complex cognition. We happened to get to the level we’re at first, but if all of humanity were to die off in some cataclysmic disaster it seems likely that another species could develop into a comparable level of accomplishment given a few tens of millions of years, or in the case of primates, possibly much less. We can’t say anything definitive about the development of intelligence but it is clearly a strategy that “evolutionary progress” dabbles with on a repeated basis with some degree of success. It certainly seems possible that life elsewhere could also develop the complex neural-like systems to support cognition. It is unlikely, however, that they would look or think anything like we do, and indeed, their modes of cognition and communication may be so literally alien that we wouldn’t even recognize an alien species as thinking without considerable study. We certainly wouldn’t be talking over hailing frequencies or exchanging views on political thought; we’d be lucky to be able to communicate on the level of basic mathematics or physics, much less any topic that innately requires a somewhat common set of shared experiences.