Well, they evolved enough intelligence to depart the planet and leave behind only bones. Plus the shield against radio signals that they put around our solar system is still working after all this time. I think that’s pretty impressive.
First of all, except for phosphorus, the primary elements involved in our CHNOPS biochemistry are formed during normal stellar fusion processes (the CNO cycle and silicon-burning), and are expunged from a star during stellar collapse and nova events. Phosphorus and many other elements heavier than iron are formed by supernova nucleosynthesis and collisions between neutron stars but these were quite common in the early universe. Our solar system is formed from the remnants of at least ten supernova nucleosynthesis events (determined from the proportions of isotope ratios of radioactive heavy elements) and many of those heavy elements drive planetary processes such as core heating and mantle convection observed on Earth and seen in the history of other solid planets, but very few heavier elements are crucial for terrestrial life and are not necessary to postulate extraterrestrial life with a different basis even if based on a CHNOPS chemistry and using primordial amnio acids (which have been found in the interstellar medium and in planetary nebulae) as a basis. The more critical timing component is the formation of galaxy structures which facilitate the transport and mixing of elements, and we’ve recently discovered the formation of spiral galaxies like our own only three billion years after the the initial singularity.
Even if we postulate a timeframe for extraterrestrial life starting at the same epoch and following a similar progression as life on Earth, only a slight variation in evolutionary parameters would permit complex and potentially intelligent life to arise tens or hundreds of millions of years previous. The development of complex life on Earth appears to have occurred concurrently with, and hypothetically the result of, catastrophic global events which radically altered evolutionary pressures and allowed new forms to rapidly expand and dominate. The expansion of mammals as the dominant macrospecies on Earth has only occurred within the last 65 Mya following the Cretaceous–Paleogene (K–Pg) extinction event, and primates only within about the last 10 Mya, giving plenty of time for some other variation of evolution to have advanced technological innovation by millions of years.
Gamma ray bursts (GRB) would be a hazard to us because they would strip away the ozone layer and result in lethal levels (to us) of ultraviolet radiation from the Sun to sterilize the surface, but that would neither kill all life on Earth (the oceans would likely be fine, as likely would any subsurface terrestrial life unless solely dependent upon terrestrial photosynthesis, nor would it apply to an extraterrestrial life that did not require a protective ozone layer.
One of the developing hypotheses in astrobiology is that life may actually be most common in the large moons of Jovian-type planets with subsurface liquid oceans like Enceledus, Europa, or Titan, particularly around stable red dwarf or smaller K-type stars as it would be protected from radiation due to solar flares and would likely rely on some kind of chemosynthesis driving by tidal energy or internal radioactivity. Terrestrial Earth-like planets require some fairly knife-edge conditions to remain habitable (and Mars, which likely once had a potentially habitable protobiosphere, is evidence of this). At any rate, GRBs are highly focused beams of radiation, and a system that is not in close proximity to a collection of supernovae are unlikely to be struck by a GRB within the span of the evolution of life on Earth.
We can’t really say that “there appears to be nothing out there” without acknowledging that our current ability to detect signs of extraterrestrial life somewhere else in the galaxy are so limited it is like making a culinary assessment of Paris by going to the Hilton and ordering room service. We have only looked for deliberate signals with one fairly narrow band of electromagnetic radiation over a small piece of the sky, and could only plausibly detect signals at a distance of a few thousand light years even if they were deliberately aimed at us unless sent using a transmitter with an output on the order of a medium sized star. We lack the means to look for signals in other mediums, such as modulated gravity waves or any kind of exotic physics, and we can’t even observe a significant part of our own galaxy because of extinction due to clouds of interstellar dust and the so-called “Zone of Avoidance” around the core of the galaxy.
One of the most contrived arguments is that even if an alien intelligence were not deliberately trying to communicate with us we would still observe them through their constructs and signals to each other because they would ‘naturally’ evolve into a stellar and then galactic (Kardashev Type II and Type III) civilization, harnessing energy and creating structures that would be evident. That we don’t see this either in our galaxy or in others is evidence, some suggest, that other intelligent life either does not exist or extinguishes itself before developing the technologies to expand into space or communicate across interstellar distances. However, this comes from a very human presumption that an advanced species would necessarily expand in this way. In fact, it may well be that an advanced technological civilization will find other sources of energy that do not require harnessing the crude and often unstable natural fusion cycle of stars, or may rapidly advance beyond the exploration of our observable universe and into other domains that we have yet to conceive of, or may exist but desire to preserve the natural evolution of stars and galaxies just as we preserve forests and wetlands even at the expense of opportunity cost. We can no more conceive of the motivations and drives, much less the technologies, of a civilization which may be millions of years advanced compared to our own any more than our hominid ancestors could predict our evolution and technology. And aliens may have less use for deliberately communicating with us than we would with Homo habilis.
In other words, “Absence of evidence is not evidence of absence”. All we can infer from our lack of observing advanced alien civilizations is that our crude instruments looking from one position in a fairly remote location of our galaxy are not currently capable of seeing evidence of technologically advanced intelligent life, nor likely of interpreting or understanding any kind of signal we might incidentally intercept; nor would an advanced alien intelligence necessarily be interested in communicating with us out of some kind of insatiable curiosity or benevolent inclusiveness.
The “tech we take for granted” is but one possible path to an advanced industrial society capable of eventually exploring or living off of its home planet (or whatever environment it evolved in). It may not even be particularly the best environment. A species with an innate ability to modify it self (genetically, if it has some analogue to genes, or by whatever heritable means it uses to construct and reproduce itself) may have a significant advantage over our frankly crude usage of tools with grasping appendages that do as much to limit our interaction as they do to facilitate it. While much of science fiction, and especially that on film and television, has portrayed alien species as just some kind of variation of humans (often with laughably stereotypical an d social monocultured behavior) actual intelligent aliens would almost certainly look nothing like primates or think and communicate in a way that would be comparable. We might not even immediately recognize an intelligence alien species or vice versa, particularly if they perceive the world on a vastly different timescale.
Fire, stone tools, paper and ink, and radio transmission have been the major milestones in our technological development, but that is no guarantee that an alien intelligence wouldn’t evolve in a completely different fashion, perhaps using enzymes (or the analogue) to separate materials and produce complex industry. The most seemingly improbable (but physically practicable) speculations are probably not wild enough in evaluating how an alien industrial society might develop. Humanoids beating rocks together and expelling air across a variable aperture orifice made of meat might be the least likely.
Stranger
But, the thing is, it only would require one intelligence to be similar enough to our experiences that they would do what we plan on doing. The idea that there are many other intelligences out there, but not a single one that would follow that pathway, is IMHO, less likely than us being the only ones.
There could be many intelligences that expand in different ways, or don’t expand at all. But that there is not a single one that expands in a way that we would notice is what I find hard to fathom.
Unless there is collusion amongst these alien intelligences, in preventing other species from deploying such noticeable technology, I don’t see why that would be. If there is, we should see them showing up fairly soon to stop us from doing what we are planning on doing.
The only alternative that I see to that is that every intelligence that is on the path that we are on destroys itself, but the idea that the great filter is in our future, rather than our past is not a new one, just a depressing one.
Yeah. One would think that an interstellar civilization would communicate by sending directed signals to each other, and not use the energy inefficient method of broadcasting the signal in all directions.
Plus, consider TV signals today. Not long ago TV broadcasts would be easy to decode. Today digital TV signals assume a complex protocol and might look a lot more like noise. The length of time a culture broadcasts easy to intercept and decode signals might be very limited. Aliens might be listening into “I Love Lucy” but they aren’t listening in to “Game of Thrones.”
We don’t currently have any kind of “plan” for doing anything beyond some vague concepts of interplanetary exploration and colonization, and those likely bear less resemblance as to what an interplanetary civilization actually looks like as “New Amsterdam” does to the Lower Manhattan Financial District today. If you asked a conquistador about interstellar expectation they would imagine raiding native civilizations for gold and slaves; a 19th Century colonialist would imagine rubber plantations and opium trade; a 1960s Star Trek fan would no doubt imagine sexy green skinned women and logically minded aliens with bowl cuts manually flying a star cruiser and dealing with trade empires; and all of them would be reflecting a projection of their own experience onto a future with technical and social innovations they have yet to envision or be exposed to.
In fact, there is little reason for an advanced civilization to absorb every resource in the pursuit of pure population growth, as the need for endless population growth is rooted in agriculture (more hands to grow and distribute food) rather than in a post-scarcity economy in which “excess” population (that not contributing to intellectual advancement) is a burden rather than a benefit. Indeed, in our own industrial societies we’ve observed a consistent trend of reduction in population growth to the point that many nations now have negative population growth rates. Even if we assume that exploration is some kind of societal imperative for any species, expanding to consume all resources is not the most likely or sensible notion for the same reason that when you go on vacation you don’t try to eat all the food at every restaurant in your destination. If the desire to explore the galaxy in the most rapid fashion is the goal, building probes that can travel over interstellar distances with the minimum energy and resources required for a given time interval makes far more sense than trying to convert all energy and useful materials into some kind of massive depot.
The notion of going to another star system to mine and return its resources, build an empire, or ship materials from one system to another in some kind of galactic version of “Age of Sail” trade routes just doesn’t reflect that the time and distance required just doesn’t make this viable without some kind of science fictional cheap superluminal transportation that is beyond physics as we currently know it, and even if the latter existed, it would likely imply an understanding of the natural world and a command of energies that would direct an alien society to develop in ways beyond our comprehension. It is far more plausible that an advanced alien intelligence might become more interested in using its resources with greatest efficiency, or exploring new physics beyond anything speculated by human cosmologists, or any another of a multitude of intellectual exercises that do not require building megastructures or transmitting enormously powerful radio-frequency signals across the galaxy.
Stranger
I agree, and FTR, I’m on the side of “there’s probably an enormous amount of life in the universe, much of it intelligent, and much of it much older than the earth”. I’m just saying that “there appears to be nothing out there, no matter how hard we look” seems like a pretty remarkable fact, even though there are plausible explanations, as I said and as you explained. But in the early part of the 20th century, before the first really big optical telescopes were built and even later when the first radio telescopes starting coming online, the prognosis for detecting alien life was totally unpredictable. If our best scientists at the time had been asked to venture a guess as to whether a careful scan with advanced instruments 50 years in the future would yield evidence of extraterrestrial intelligence, they would not have had a clue. It could have gone either way.
Or fly around insulting everyone in alphabetical order.
I think the bullshit lies not in the Drake equation itself but in any attempt to treat it as a real equation, one that can be solved or has any value in terms of predicting anything.
If x = unknown x unknown x unknown x unknown, x is not going to be known or knowable. As far as I know, Drake only intended it as a spur to discussion.
I think that in order to get a reliable number out of the Drake equation, we’d need enough knowledge to have a pretty good idea of the answer already. For example, knowing a reasonably accurate value for the chance of life forming on a planet that could support life would require a large enough sample of planets that could support life and knowing which ones do and don’t have life on them.
As for the Fermi paradox, I’m not convinced that it is a paradox. The scale of space is incomprehensible. There could be a thousand civilisations at least as advanced as us in this galaxy alone without any of them having any evidence of any of the others. I think it’s likely that civilisations with more advanced technology (if there are any) would be harder to detect, not easier. More advanced technology very strongly tends to be more efficient and throwing strong signals into space for no purpose is not more efficient. Unless they were deliberately broadcasting their existence, I doubt if they would be detectable from any significant distance.
.
Bunkum.
Maxwell theorized the existence of radio waves in 1870s. We’ve come quite in the less than 150 years since.
Consider how much further we’d be if Galileo had developed the radio telescope in 1610, rather than “merely” an improved refracting telescope with 20x magnification that he did.
You are thinking that scientific developments are a linear progression.
More usually they are both exponential and autocatalytic.
Wow. Just checked back in after a long day of work and some family time. Plenty of smart people have contributed greatly to this thread as I knew would happen, but the depth of knowledge and interest in the subject behind your posts is impressive. May I ask where it comes from, Stranger? Are you employed in some scientific capacity, or are you a very well-read layperson?
If there are thousands of advanced civilisations in our galaxy, why are none of them ‘deliberately broadcasting their existence’? I like to assume, on very little evidence, that each of those ‘thousands of civilisation’ are unique and the product of a long chain of stochastic events. Why, then, should they all come to the same conclusion and decide to keep quiet?
Perhaps the answer is paranoia. A sufficiently advanced civilisation might look at the quiet sky and think that maybe the risks of broadcasting one’s existence are too great. There may or may not be dragons out there, but it might be wise to act as if there were. I find it almost impossible to believe that every one of these vastly diverse and alien civilisations have all spontaneously come to the same egregious conclusion without evidence.
Perhaps, instead, these civilisations are all busily communicating with each other on an undetectable channel. The Interstellar Internet, as it is sometimes called. One wonders how a new civilisation (such as our own) gets to be invited into this club.
Or maybe there really are dragons out there.
I would expect that somewhere out there are creatures that we’d describe as dragons.
Obligatory HHGTTG quote.
The chances another sentient life form making/receiving contact with us and being at the same level of sophistication as ourselves is very low. They can’t be less advanced than us or they wouldn’t be able to interpret our electromagnetic footprints. So they will be significantly in advance of us. There’s no reason to think they’d be best pleased at our presence and our own history of colonisation here would suggest that we shouldn’t rely on their benevolence either.
This reminds me of a joke I read once, maybe one of you can help me remember where I may have seen it. It presents a quote (which I will paraphrase from memory, so I may be off), and then attributes it humorously:
“The odds that our species is the first to become intelligent and reach space are so low that it is safe to assume that we are not that first species” ~every statistician from the first species to become intelligent and reach space.
Let’s see if I can summarize the theories given so far for why we haven’t detected life elsewhere yet:
- Life is exceedingly rare, perhaps confined to Earth only (Cornell study premise)
- Technologically advanced life is rare
- We’re the first! (Yes, this theory’s been beaten up badly here, but someone’s gotta be first)
- Technologically advanced societies typically destroy themselves before they put a significant footprint into space
- There are other advanced life forms, but they evolved to communicate and use energy in ways that are so alien to us that we are unable to detect their existence.
- There are other advanced life forms, but they don’t go about advertising their existence because it’s a dangerous universe out there.
Did I miss any?
Forgot this one:
- Technologically advanced lifeforms exist, but due to the vast size of space and the limitation of the speed of light, we haven’t been able to detect them yet (our “space footprint” in the form of radio signals only extends out to about a 100 light year radius).
Agreed that there is no comprehensive “plan” as such, but the road is in front of us. We are starting down the road of asteroid mining right now.
I get that there are popular idea in Sci-Fi that are not reasonable, but that doesn’t mean that all predictions to the future are without use.
My point is only that there does not seem to be an obstacle to prevent us from creating a permanent and productive presence in space, and once that happens, there’s little to stop us from expanding that presence.
If there are obstacles, then that would be a solution to the Fermi paradox.
I disagree that more population is not a good thing on its own. More perspectives, more thoughts. The entire point of having a civilization is to give humans time to sit around and think about the universe. The more people we have doing that, the further we go. The more people we have, the more people we have to either push the boundaries of knowledge and thought, or to at least find ways of entertaining those people. I am under no illusion that we will retain these meat bags without extensive modifications, maybe even going the route of fully cyborging or even uploading. But, having more individual perspectives is, IMHO, the entire goal of civilization, not just a by product.
Nations having a shrinking population is not because that is what is good for the nation, but that individuals make different choices. Having kids is a lower priority for the individual people, but that doesn’t mean that we don’t need a growing population in order to have a growing economy and standard of living. It’s expensive and hard to raise a child these days, and the effort never really pays off to the parents the way it did when you had kids to work on the farm. Post scarcity and life extension would change that. The cost of having and raising kids could be negligible, and them being immortal as well as you are means that your investment will pay off continuously forever.
We don’t need to travel to another star system to make ourselves known. Look at “tabby’s star”. That turned out to probably be natural phenomena, but it is something that we could detect from over a thousand light years away, and is pretty similar to what our solar system could look like in just a few centuries. I doubt that there would be much travel between stars, as there is little point, but stars aren’t that far apart, on the grand scheme of things. At some point, colonizing or exploiting the Oort cloud, you find that you are actually closer to another star than to Sol, and that the material that is around to be exploited is increasing as you get closer. Expanding into neighboring solar systems is just a matter of expansion.
The closest I would see of just mining another system for resources would be automated self replicating factories that you send to another system to start mining and sending materials back, which is a possible route, and a route that would be noticable.
Finally, there is the matter of immortality. If we are to become effectively immortal, then conservation becomes important. And we are not just talking recycling your aluminum cans. Every second, the galaxy consumes enough energy to last, if used more conservatively, billions or even trillions of years. It would be prudent to start going around and turning off stars as soon as you have the technology to do so. That would be something very noticable.
Like I said, to me, the idea that intelligent space faring life is common, but that we are unique in our desires for growth and expansion is less likely than us just being unique in being intelligent space faring life.
No, we are starting down the road of saying “wouldn’t it be cool to mine asteroids?”, just like we are going down the road of saying “wouldn’t it be cool if everyone had flying cars?”.
We are a bit further along on both of those than your dismissive comments indicate you believe.
Japan has a sample return mission rendezvousing with an asteroid in the next month. That’s much further along than, “wouldn’t it be cool”.
There are private enterprises that are interested in making trillions of dollars off returning rare earths and platinum group metals to earth, along with keeping the more base materials like iron in space for manufacturing further infrastructure. Iron is $400 a ton on earth, add a few thousand per pound to its value if it is already in orbit. Building satellites in orbit, rather than launching them, will drastically cut costs, even if all the electronics and other special equipment is built on earth and just the frame is built in space. A company that can build a satellite in orbit for a fraction of the cost of building it on the ground and then launching it will become wealthy very quickly.
Can you explore any obstacles in science or technology that would prevent us from exploiting the resources available in space? A lack of will is about the only obstacle that I can see, and while it does seem as though the US is largely giving up on space exploration and exploitation, the rest of the world is not.
Oh, and flying cars are easy. Every few years someone comes out with one. They all have one problem in common though, people are supposed to drive/fly them, and we don’t really trust them to do so.
I am aware that there are many more theories. I was attempting to summarize the ones brought up and discussed in this thread.