Fermi Paradox. What am I missing?

Factual Questions
81

I quoted this post separately because it gets back to the main post of this thread – so I wanted to keep it separated from the side discussion about how likely it is that we will continue to advance, and how far we might go.

Because Fermi noted that something was off, even at our current level of tech.

The point of the Fermi Paradox is that even if it took 10,000 years to do this, what else is a 500,000 year old civilization going to be doing? I would definitely hope that by the time our civilization is 500,000 years old, we will have developed enough not to be spending most of our resources in conflict with one another. At some point during that time, would no one have decided to carry out such a project, no matter the cost?

Let’s say we stagnate technologically. Imagine that in 2,000 years, Earth has a population of 15 billion, and the growth only occurred because we got our food distribution issues figured out. Maybe there’s only one United government, or maybe independent governments just figure their shit out and stop fighting. It’s a very prosperous period.

We have no issues feeding everybody, we have no problem meeting everybody’s basic needs. They’re also running a huge surplus. You’re saying a civilization like that wouldn’t want to colonize another world, just to say they did?

Now let’s say that we take technologies we know about and apply them on a large scale, because we had 2,000 years to research them. How many people can we feed in greenhouses (which are many, many times more productive per acre) growing genetically modified crops? How long do our children live, thanks to advances in gene therapy, artificial organs, etc? Even if we can’t do anything about aging itself – how close does the average person get to the apparent limit of 120? How much can we produce, with 2,000 years of increased automation?

And if we assume that there are technologies we don’t even know of yet, new applications of fields we only begin to understand – but assuming our knowledge of physical laws hold – how prosperous are we then?

Now realize that our sun is relatively young. If Earth isn’t special, and neither are we humans, then there was probably life - and even intelligent life - before us. After all, there are so many planets out there. What if one – just one – developed life right after Earth did, but while dinosaurs ruled the earth for over two hundred million years, their equivalent to amphibians crawled out of the sea and developed intelligence then and there? Twelve million years later, while we’re still in the Triassic, they put a frog on the moon.

Assuming their species didn’t go extinct, what are they doing during the Jurassic? How advanced are they by the Cretaceous?

And what about a planet that cooled around its sun a full billion years before Earth did?

If we survive that long, in the year 1,002,019, what will we be doing? I doubt we would even recognize ourselves – but if we are still alive and still intelligent, I can’t see how we wouldn’t have decided to colonize the stars at least once. I’m sure it would have happened long before a million years from now, too. In fact, I would bet that in a thousand years, we’ve either been to Alpha Centauri or gone extinct.

If that’s the case, a species that evolved a billion years before we did, or even while the dinosaurs were stomping around, should be everywhere by now, no matter how hard interstellar travel is.

Therefore, either life itself is rare (And when I say “rare” I mean “once in a galaxy”); or complex life very rarely evolves from single celled life; or intelligence rarely arises in complex life; or intelligent life rarely forms civilization; or civilizations rarely become technologically advanced; or something prevents technologically advanced civilizations (like us) from becoming spacefaring.

That last one is the scary one. If we discover alien microbes in Europa’s ocean, that tells us that life is most likely pretty common. If we find alien fish or cephalopods or even tubeworms near vents or something so alien it doesn’t have a good analogue on Europa, that’s evidence that complex life is common. But if SETI finds a another planet-bound alien race, about the same age as us, out there in the universe – that’s bad news. That tells us that we are pretty common, too – we aren’t over the hurdle that wipes out most species. In other words – we’re probably about to go extinct.

82

I understand the augment, but it is anthropocentric and subject to selection bias.

While I get that you can’t imagine not becoming becoming spacefaring, what if a alien realized that given the right condition life will likely develop and if they visit it they may cause collapse of that world by introducing their lifeforms to that ecosystem. If they could only reach those places after a huge investment and the travel times are so long that they wouldn’t be the same when they arrived perhaps they just don’t fear endings as much.

While I won’t personally call it purely selfish, the assumption that conquest despite the costs is worth it really requires one to believe their own form of life is intrinsically more valuable. Perhaps they just value life, despite the origin more than they value a perpetual lineage of their own.

To assume that another form of intelligent life has the same motivations and aspirations as humans ignores that the possibilities on what could arise are probably unbounded.

For us humans, yes I am doubtful if our biology will allow for long term survival outside of our protective magnetosphere and with gravity. But if you have evidence that is not a concern please share it. I am always happier to be corrected than to win a point.

83

Some aliens may very well not be expansionist. But unless there’s something inherent to becoming advanced enough to colonize other stars that makes you adopt this view, then this does not solve the Fermi Paradox because the galaxy is so big in both space and time that eventually one of the civilizations that got to our level of development should have been expansionist (unless either being expansionist in itself prevents you from becoming spacefaring, or becoming spacefaring in some way makes you less expansionist, every single time [or at least a vast, vast majority of the time])

In other words – if civilizations commonly reach the spacefaring stage, but choose to remain within their own solar system, at least one civilization should have bucked the trend and become expansionist. So either civilizations at this level are very uncommon in the first place, or there’s something that causes an overwhelming majority of civs to stay at home. I just don’t see it. Sure, you described a peaceful civilization, but I would argue that an aggressive, expansionist species is more likely to become dominant on its hokme planet anyways. And those instincts last – we are on the cusp of the space age, and in many ways, we are still the same old apes.

84

Probably comes under Fermi’s reported third reason, technological civilizations that have no problem with following actions that cause massive loss in life probably also won’t care about starting wars that end their own civilization.

But we have to get way past our current tech stage for interstellar expansion. Despite your posts claiming I claimed we will never get there I am stating it is unknown if we can and many challenges limit our ability to do so now.

My position is that it is unknowable if this is even a good test until we develop technologies or at least know they are possible. The argument from ignorance is that this outcome is inevitable. We simply do not have enough knowledge today to make that claim.

85

Ok, I’m quite angry to see this post of yours. Let me express why : I feel you are being willfully ignorant, but you’re using terms that imply you’ve thought it through.

So the first point. Selection bias. What sort of creatures are likely to even reach the point of technologically sophisticated life in the first place, in any kind of competitive evolutionary environment? Selection bias - your word - means that the creatures will be ones that reproduce about as often as an opportunity to do so comes up (once the environment is very crowded and it takes vast parental resources, aka high R strategy organisms, the reproduction rate drops because valid opportunities are less) and they will likely have traits that cause some of them to seek out risky new opportunities.

And even if you posit some sort of lazy cowardly alien form of life, it is reasonable to expect that some variants of that life - or, over a million+ years, as different civilizations rise and fall - eventually the dice are going to come up in favor of a variant that desires interstellar travel enough to attempt it.

And as the selection bias plays out over the following megayears, you would expect the process to keep accelerating, because as more and more star systems are conquered, out of the total population of that species, more and more of them would have strong traits for expansion. (because the expansive subgroups take over more stars and gain more space and resources and thus become a larger and larger percentage of the whole)

And the second. I’m going to flip it the other way. What evidence do you have that humans cannot eventually build artificially intelligent beings? Even if they have to do so by making direct analogs of human neural circuits, patterned into silicon or diamond in 3 dimensions - this form of computer would be an analog replica of the human mind. Every bit of understanding we have of physics suggests that if you duplicate a computation, even if you do so using a different medium or substrate, the calculation is the same. (and you don’t have to duplicate the calculation, as long as the output : input mapping is the same it’s valid, even if the math used internally is very different)

Anyways, however long it takes (I of course think it’s not nearly that hard and we will have digital computer based AI before 2100), even if it takes a million years, artificial brains made of more durable material would allow you to deal with the lifespan limits, the radiation damage (through redundancy and copying files around, I am well aware that current computer chips are more vulnerable to radiation than humans in the short term), boredom or the need for habitats, and so on and so forth.

Interstellar travel is a heck of a lot more feasible for a being that can slow it’s perception of time so that a thousand year journey takes 5 minutes, that exists in an armored capsule out in the vacuum, that has no other needs besides a trickle of power and occasional replacement of a compute node.

86

[QUOTE=rat avatar;21437127
While I won’t personally call it purely selfish, the assumption that conquest despite the costs is worth it really requires one to believe their own form of life is intrinsically more valuable. Perhaps they just value life, despite the origin more than they value a perpetual lineage of their own.

To assume that another form of intelligent life has the same motivations and aspirations as humans ignores that the possibilities on what could arise are probably unbounded.[/QUOTE]

It’s not about assuming aliens will have traits like humans.
It’s that we would have to assume something like the opposite: that all sentient species, apart from humans, possess the trait of not wanting to colonize other planets for that to be the primary solution to the paradox.
It would be making a baseless claim, not thinking skeptically.

Also in terms of space, I think terms like “conquest” are pretty misleading. The vast majority of the universe is not only devoid of any life but probably many light years away from being able to have influence on other life, and is basically free resources.
It’s a very different prospect to expanding territory on earth.

(But I note that there aren’t many good alternatives: “expansionist” and “colonizing” on earth have negative connotations as they usually means war or oppressing other peoples)

87

Absence of evidence is not evidence of absence.

Speculation on potential future technologies doesn’t change that fact.

88

“Civilizations end up not spending incredibly huge amounts of energy, materials, and effort on projects that do not actually benefit them” actually is a perfectly reasonable answer to the “paradox.” Humans have expanded into ecological niches when it’s profitable and fairly easy, but humans have not colonized the poles or oceans, even though those are much cheaper and easier to colonize than space. Humans will move to large cities and fertile areas, but do not feel a need to fill up all possible living spaces - the existence of ghost towns in the US west is a clear example of that.

Asserting that something that we have not seen happen a single time and that requires hypothetical alien civilizations to do the opposite of what our one example has done is so common that it MUST have happened just doesn’t make any sense. Our current evidence points to technological civilization taking a long time to arise and being rare. Our current science doesn’t point to interstellar colonization becoming cheap or making sense while expensive and difficult. Current speculation does point to the possibility of advanced intelligence finding things to do other than spread itself to other solar systems. There’s just nothing to rule out the rather boring explanation that high tech civilizations are rare and tend to either destroy themselves or develop in a way that doesn’t support massive colonization projects.

89

The point isn’t whether it’s common or not. The point is that even if only 1 percent or .01 percent of civilizations are expansionist, the universe is so old and so big that in the last few billion years dozens of them should have already done so – unless something makes these civilizations incredibly rare and unlikely to arise in the first place.

Expansion doesn’t necessarily mean colonization either. If we send self-replicating probes (which is certainly possible in theory-- WE re self-replicating and there’s no law of physics that makes it so that only organic organisms can self-replicate) out to another star, they could quickly reach every part of the galaxy. And WE are getting pretty close to the point where we could do something like that. So a civilization with a billion years head start should have done so by now.

This is an even more glaring issue, because it only takes one scientist in one alien Empire to build one self replicating probe and send it out, and the universe is so old and vast that if civilizations at our level of development are common, there should have been millions of such alien scientists by now.

Unless reaching that level of technology is incredibly uncommon, which seems much more likely than the idea that there are many advanced civilizations out there, but not a single one has ever been interested in space exploration until us.

Mind you, the argument that “the universe is very, we took millions of years to evolve, and someone should have done it by now” would seem just as logical to a member of the first interstellar alien race in the galaxy as it would to us. Sure, the odds of being first are astronomically low, but SOMEBODY was first, right?

90

There are lots of plausible “solutions” to the paradox. The point is, we don’t know at this time which one is correct, or which combination, or indeed if there is some reason we are not aware of yet.

Once again: Fermi’s paradox is not about asserting anything.
Put it this way: the universe could be sterile of life except on one planet. Or it could have abundant life but only one became sentient. Or perhaps it’s just, as you say, that technological civilizations take a long time and humans are one of the very first across the line.

We don’t know which of these, or other possibilities, is correct. What we do know is that there is no noisy galactic empire in our galaxy or plague of self-replicating bots. But we don’t know for sure why that’s the case.

We could say “Let’s call the whole thing off: we will have no idea about ET life until someone visits us or we explore other star systems”. But there’s plenty we have been able to figure out about the cosmos from the comfort of our own solar system. Why not put together models, and try to find supporting data to support or rule out some of the possibilities?

91

I think the key point is this. We can all come up with lots of reasons why a spacefaring civilization might not develop, but unless that reason is nearly absolute (not just “maybe they’re happy to stay at home” – that’s not enough, imagining a civilization that doesn’t expand isn’t a paradox “solution” unless EVERY (or damn close to every) civilization would give up expansion for that very reason.

It’s also possible that civilizations will one day be incredibly common, but we evolved a billion years too soon to meet everyone else. That’s incredibly unlikely, but like I said before – it would appear incredibly unlikely even if it were true.

92

The scariest possibility to me is that we have the bad luck to be in a universe where some hidden trap in physical laws will kill our ability to ever expand. Like something where complex objects aren’t supported by spacetime itself when away from a star or it’s actually pretty easy to locally destabilize the vacuum and for one jerk to sterilize our whole star system. Or in science fiction stories, where the universe is seeded with a disease that kills technologically advanced life once they encounter it.

I can’t deny these things seem possible, maybe even the most probable possibility.

93

Not if there was no beginning. Maybe time isn’t actually linear after all.

94

What does that mean?

95

Conjecture. Time is actually something we humans invented, based on the apparent movements of our own sun, but it really is a particularly human awareness. There is no really good reason to assume that our understanding of time is actually accurate. Why must the universe have a beginning and an end, for example? Maybe it just always was and always will be.

96

Time isn’t human perception; it’s a fundamental part of the universe. Anything that has mass experiences time (which is really just a measure of how often the massless parrticles that make up mass particles like atoms or electrons interact with each other – that’s why accelerating slows down time – the classless particles within the atom have to move further to interact with each other, and they move at the speed of light).

And we know that causality only travels olne way, from the big bang towards entropy.

That’s another thing – there is TONS of evidence of the Big Bang.

97

Clarification: time is relative. The flow of time isn’t constant. But that doesn’t make it less real.

98

I think there is a difference between ‘new physics’ and better engineering.
New physics would be discovering a way to travel faster than light.

Better engineering would be working out a way to get round the tyranny of the rocket equation. That might be a pipe dream, but the late Robert Forward and the more recently late Jordin Kare had some ideas that might help in this respect. I apologise if you are already aware of these concepts (you may have very good reasons to reject them, and I’d be interested to hear those reasons).

Jordin Kare’s ideas were particularly interesting. What is a rocket except an object with an explosion happening inside one end? In a rocket that carries its own fuel and propellant, that fuel and propellant needs to be accelerated along with the payload until the time it needs to be used; this requirement needs more fuel to accelerate the fuel, and that extra fuel also needs to be accelerated, and so on. What if you could have the fuel delivered to the ship while it was in flight?

Kare’s idea is that small pellets could be accelerated to intercept the back end of the rocket, and would react with a cloud of plasma that is contained inside the rocket’s reaction bell. Where does this cloud of plasma come from? Well, when you first start the ‘rocket’ up. you’d need to expend a little bit of fuel carried on board the ship, to create a cloud to start the process. After this time the cloud would be formed by the reaction products of the fuel pellet stream. Most, or all, or the energy that is produced in such a concept comes from the momentum of the pellets themselves- this concept is basically a ‘momentum gun’ that transfers thrust from a series of stationary projectors inside the Solar System. I have seen concepts where the pellets include frozen deuterium to add a bit of ‘boom’ but that may not be necessary.

This idea obviously needs a lot of refinement, but the challenges are challenges in engineering, not challenges to accepted physics. How could the ‘pellet stream’ be accelerated? Kare suggested that they could consist of small sheets of diamond accelerated by laserbeams.

Each pellet could include just enough navigation capacity that they could ‘home in’ on a beacon placed at the back of the rocket ship. I suspect that we’ll start working on smart pellet delivery systems fairly soon, if we haven’t already; eventually the biggest engineering challenge will be finding a way of transferring enough momentum to the ship without melting it.

Oh, and slowing it down at the other end, which even more of a challenge. There are ways round that too, but they have their own problems. Until a pellet stream generator is built at the far end as well, of course.

I would class this as speculative fiction, rather than the (nearly) baseless wishful thinking of warp drive.

99

If you look at papers about this like:

“Interstellar Probes Propelled by Self-steering Momentum Transfer Particles” (IAA-01-IAA.4.1.05, 52nd International Astronautical Congress, Toulouse, France, 1-5 Oct 2001).

You will note how they are still resorting to Dyson spheres or fusion, yet only reaching 0.045 c.

900,000,000,000,000,000,000,000 joules or 138,888,888 TWh when the world currently is thought to have total primary energy supply 157,500 TWh

That is 881 Earths worth of energy, and while a useful thought experiment to consider this specific problem they only can claim to use “known physics” because they are ignoring the unsolved problems with Dyson spheres etc…

Note this part:

25,000,000 TWh / 157,500 TWh = 158.73 worlds total annual energy consumption so the authors are a bit loose with “about a hundred times” especially seeing as they claimed “non-food”

Also note how they leave the problem of “anchoring” these beam generators to be solved later:

Remember while from the space ships frame this solution may help with the exponential problems of carrying your propellant with you, for the generating stations this ejection of mass would function as a “rocket engine” pushing itself the other direction.

Researchers have to simplify to work on specific portions of this problem but that “spherical cow” doesn’t mean that those other concerns don’t exist. While they may be able to simplify and work on the problem they are considering, ignoring the rest of the system doesn’t make this “obtainable”.

A laser or a particle beam would experience a thrust just from emitting the beam. While the vehicle does not carry either the energy source or the reaction mass for propulsion, the other side needs to deal with the energy needs and will need to counter act those forces.

While the trust of a flashlight, and the mass it loses when producing that light may be too small to calculate, a 3 Petawatt laser or particle beam would be subject to that same Tsiolkovsky rocket equation.

Note there are lots of problems which will require “new physics” that are hand waved away, consider the issues with the heat energy from the colliding particles or ensuring that energy is captured and not radiated in a way that would cause the ship to go off course.

Which completely goes against the “known physics” claim as they are ignoring the challenges of ablation of the surface being hit at the above energy levels and ignoring that magnetic flux won’t be 100% efficient or “friction-less”

Note that effects like the Unruh effect may be problematic with the macroscopic self steering mass-beam objects. But as that link will show we don’t know.

But yes if you ignore the challenges on generating, delivering, and using the energy you can structure thought experiments to work within a specific area of interest. Spherical cows are critical to working on physics. But holding spherical cows as sacred is antithetical to implementation in this case.

For a ship with a non-fuel mass of 10e+4 kg with an average velocity of 0.06 c, the propulsion energy of the propellantless ship 3.3e+18 Joules, vs the rocket version 2.3e+19 if you assume super high efficiencies and ignore the energy required to counter acceleration etc…

There are also challanges related to runaway electrons and whistler waves that the papers on this tend to ignore. Although there is a lot of work going on related to that with the fusion reactor efforts so that may be solved. But the fact that they invoke converting relativistic particles to plasma and magnetic mirrors as reflectors, the fact that these challenges weren’t even addressed shows how undeveloped these ideas are needed.

In other words the “spherical cow” that this idea developed intentionally simplified the troublesome “limbs” of the unknown to focus on one problem. But the fact that they simplified away these issues doesn’t mean that we can solve those problems based on what we know now.

While we may solve those in the future (or find that they are hard limits) the point is that we cannot ‘assume’ they will be solved and thus make any claim about how common life is in the universe. As I said before an absence of evidence is not evidence of absence. If and when we do figure out interstellar travel for ourselves we can use that as a constraint on where we look for other life, either technological, simple life, but it will never “rule out” the existence but rather just provide constraints.

100

Thanks! That is a very interesting link. Incidentally I have been in communication with one of the authors of that paper fairly recently, so he might be a bit miffed that I haven’t read it yet.

Of course to get 881x the Earth’s energy consumption you don’t need a complete Dyson sphere, just one which collects less than a millionth of the Sun’s energy.

On the other hand we should be able to detect a Dyson Sphere even if it only collects such a tiny fraction of the luminosity of a star- the fact that we haven’t seen one yet seems to suggest that there aren’t many aliens out there using this method. So we are back to square one.