Alas, there's a fifth possibility:
5. Controlled transportation between the stars, sufficient for colonization, is sufficiently impractical that there are no grabby aliens within our light-cone.
5. Controlled transportation between the stars, sufficient for colonization, is sufficiently impractical that there are no grabby aliens within our light-cone.
The dynamics which would make it impossible on any known timespan don't seem currently observable.
Just with state-controlled nuclear weapons we've been on the brink of extinction a couple of times already, the energy levels required for star-travel implies this kind of destructive power being in the hands of even more people (and by necessity more or less out of control of the nation states). A commercial airliner took down WTC, a starship would be an WMD capable of taking out a city (or more).
One implication of this is that there's a chance that we've already invented practical fusion power, but if it's trivial to miniaturize AND weaponize then people in control of it have decided to withhold it to avoid every weird terrorist group creating one.
1: Considering the amount of rocket fuel we need to leave earths atmosphere and reach the Moon, people have been proposing nuclear rockets to reach Mars. That's still within the solar system, reaching another star requires magnitudes more energy, even more so to accomplish enough acceleration to reach another star within a persons lifetime. Such a mode of energy generation not having an explosive failure more feels unlikely (thus making it blow up in a dock is enough).
2: Barring option 1, reaching fractional light speeds, would not a ship need enormously more capable shields than anything today to safeguard humans? The Tunguska event(3-5 mt) was at "just" 27km/s of a 50 meter object.
3: Speaking of Tunguska, even if the ship itself would lack such shields (however a human would be expected to survive w/o one), a ship capable of interstellar travel should be able to push out a rock and then accelerate it back to earth to create a Tunguska (or larger) event at a target location.
The core issue is the energy levels required(1), converting them to something destructive is usually within grasp of less intelligent people than those that research the advances that make them available.
1: https://www.sciencedirect.com/science/article/abs/pii/009457...
TL;DR; quotes 10^20 joules of energy, as the article says equivalent to complete fissioning of 1000 tons of Uranium.
To get a ship to hit the ground at the velocity you’re talking about a large chunk of it would need to be solid steel like a bullet basically. Space craft aren’t built like that, they need to be mostly empty space for storing propellant and people. A reactor and its shielding might survive but that’s on the scale of 5 - 10 meters and it’s still not 100% solid so it doesn’t compare to a large metallic asteroid.
Throwing rocks at a planet might work but you need the right equipment and expertise to bullseye a planet from 100 million miles away and if anyone saw you do it they could take their time intercepting the rock.
Even if our first interstellar colonies diverge immediately and some even turn into reclusive hermits, some may expand, repeating the cycle.
Hand waving away “we can’t travel through stars” because we currently don’t get it, seems like the weakest way to discuss the topic.
You/we can’t imagine it; so it must be impossible or in practically difficult? What if it turns out to be extremely easy, we’re just extremely small or extremely uninteresting? Those are far more likely topics than we already have the answers and have decided it’s not possible.
BUT, that this will be one of those very difficult tasks, so it will take many thousands or millions of years.
And so goes towards 'we are early'. So, if we are grabby, and all the other grabby aliens, are all still getting over this transportation hump.
This whole discussion is about being 'early'.
Not sure you are making a point.
Edit: The original post discusses below light speed transportation. 25% speed of light is used in the estimates.
But guess I agree, if no aliens including us, never-ever with infinite time ever develop transportation that can get up to some fraction of light speed. Then maybe no colonization ever happens, and the grabby guys stay in their system.
“We can't see any evidence because there is nothing there to see” is a possibility, grabby aliens _requires_ significant-fraction-of-C travel for the argument to hold, and it's entirely possible that it's just impractical-to-the-point-of-impossibility. (That's why I quoted it in another comment).
Yes, it's possible that we're early. It's equally possible that we're “early” because there's no concert: _everybody_ is early in a universe where the band never gets on stage and it turns out that nobody bothers colonizing the universe due to the cost and lack of benefits.
See also: “Please don't comment on whether someone read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that".” https://news.ycombinator.com/newsguidelines.html
And I can ask for clarification concerning if you read the original post, since your objection/point was already covered.
Did you read it and simply making some additional argument against it, or did you miss it entirely?
"5. Controlled transportation between the stars, sufficient for colonization, is sufficiently impractical that there are no grabby aliens within our light-cone. "
This is covered in the other points of the theory? So should I assume you read it?
"The universe isn't a rock concert, “we're here too early” is not the only possible reason why there's no band on the stage. "
"Don't be snarky. " https://news.ycombinator.com/newsguidelines.html
Ofc there are explanations for that part of the paradox as well, but the impractical travel theory doesn't cover it.
I know two things.
1. We are now already using heat mask measures, even when we are very young civ in terms of Kardashev scale. We already use simple slit heat emitters in military tech (many Stealth planes have slit nozzles and for example, Leopard tanks also use slit exhaust for same reason).
2. Even we now know about possibility of laser heat, which could emit heat directly with very high focus.
In conclusion, idea is, to surround whole civ with heat mask blanket, and make all heat exhausts directly focused on directions, where now observer expected.
Second, looks like our development now is very slow, because it should be on early stages (Kardashev scale), and old civ's should know this.
And I now support theory, that we are fortunate to be far enough, so stronger civ's are not interested in spending resources to limit our development.
I even consider might be exists some preservation pact between Big civ's, to avoid touch young civ's, for some purposes like scientific, or arts. So yes, basically, I support Zoo theory.
Although focussing emissions (not really a blanket) is possible, not only would some specific civilisation have to actually do that, it would have to be a common enough choice that every example we would otherwise have been able to see actually does choose to do that that — this gets increasingly difficult the more such examples there are: if a civilisation can build a Dyson swarm, what are they afraid of that they would want to hide? Even if one civilisation has a reason, everyone has to make this decision, regardless of how many (or few) "everyone" is.
"Dark forest" is a bad reason, as everyone with a Dyson swarm will have been able to know your planet existed and had life on it even when it was all single-cell species; a star winking out of existence is noteworthy, and easily noticed[0].
One Dyson swarm is enough to directly colonise a high percentage of all galaxies that aren't beyond the "reachable horizon"[1] of the universe. As soon as we can make artificial self-replicating machines (we know such machines can be made because all life is self-replicating nano-machines, we just don't know enough to do it completely from scratch yet), this would take us about 31 years[2] to make such a swarm.
[0] So easily noticed that we have, in fact, noticed it: https://vascoproject.org/vanishing-stars/
[1] the "reachable horizon" is how far stuff can get from here starting now given the universe is expanding and no FTL: https://upload.wikimedia.org/wikipedia/commons/8/88/Home_in_...
[2] https://www.lesswrong.com/posts/DvQ7cYxhnrZtWngvW/how-to-tak...
They assume, when have already working general AI technology and it have some limited size (volume-mass-energy consumption).
Unfortunately, we still not have GAI and even cannot predict, how large will be first practical unit.
Must admit, looks like we very close to do it, but from history of previous great technical inventions, some things takes decades to achieve production status and was repeatedly reinvented in some years after another inventor fail.
It is also possible to have a large system where humans are just a component, if this were necessary. The human-machine ratio is a function of how close the automation you have is to what you need.
If you programmer, you should know from experience or from learn, that in complex system possible just two ways to achieve reliable execution.
1. Brute force, just test as many possible scenarios as could, 99.999% is better than 99.99%, and make script for each scenario.
2. Smart, run system when tested somewhere between 70..90% and make some sort of insurance, so when happen non-tested scenario and all failing, you will pay (compensate) for harm, and make additions.
That is. Bacteria lives in comfortable environment (mostly in liquid water drop), and spent billions of slightly modified reproductions, to make solutions for all possible scenarios. You may hear, DNA of simplest bacteria are more than Million pairs, that's because of number of scenarios it successfully survive.
Space is much less comfortable environment than liquid water, it have wide range of possible parameters, I even not sure if exists some structure, which could survive in all possible space environments, so need some adaptation mechanisms, to change structure, and best is consciousness AI, which could make smart predictions of causes and reasons, and control all these machinery. And also it will have memory, to repeat moves which helps to survive when something similar happens earlier.
Irrelevant. A self-replicating system does not need to be highly reliable. Look to the past, any time over 200 years ago most families were a dozen kids because most didn't reach adulthood.
> That is. Bacteria lives in comfortable environment (mostly in liquid water drop), and spent billions of slightly modified reproductions, to make solutions for all possible scenarios. You may hear, DNA of simplest bacteria are more than Million pairs, that's because of number of scenarios it successfully survive.
False. Bacterial environments are hostile because other bacteria fight them for the same resources, including predation. Many chemicals are hazardous even in small quantities. Internal chemistry requires water in liquid form, yet there's only a narrow range of temperatures where water is liquid, and worse the chemical processes change rate significantly even within that range.
Also irrelevant, we've been using simulated evolution as a form of AI for ages already. It's not new or novel. I implemented a version of this in 30 minutes over a decade ago just to prove a point. A million bases is trivial to store, so is a billion or a trillion.
> Space is much less comfortable environment than liquid water, it have wide range of possible parameters, I even not sure if exists some structure, which could survive in all possible space environments, so need some adaptation mechanisms, to change structure, and best is consciousness AI, which could make smart predictions of causes and reasons, and control all these machinery. And also it will have memory, to repeat moves which helps to survive when something similar happens earlier.
Also false.
1. Space has far fewer parameters than water.
2. One does not need to make a single machine to survive "all possible space environments" to do this, just our solar system at 0.47-0.31 AU from the sun. We already have that, we sent probes there.
3. Consciousness is not necessary for any of that. Neither is episodic memory (though that is trivial to implement). Bacteria exist and do these things well enough with mere DNA.
Do you know mathematics? Calculate, how slow will become your Dyson swarm, if for example only 1/20 will survive?
BTW, you may hear about baby-boomers, and they are exactly caused by much improved medicine, now in EU survive near 100% children.
Calculated? Ok, now calculate, how much suffer probability of overall success, because limited resources does not accept to make 20 turns to achieve 1 successful?
> 2. One does not need to make a single machine to survive "all possible space environments" to do this, just our solar system at 0.47-0.31 AU from the sun. We already have that, we sent probes there.
Well, now I see you are just overweening human, but without real knowledge. Solar system is itself have wide parameters spectrum, but is is also significantly different from other stars environments.
> Bacteria exist
Bacteria have sacrificed billions lives, to gather information, to achieve current success rate.
But must admit, I will consider idea you suggest me, about send hopeless missions, to just gather info, and I'm sure you also lazy, so I'll myself calculate success rate for each sacrifice rate.
It means the real reproduction time is t/f, where t is the time it takes to make a single unit and f is the fraction of units which survive to further reproduction. For 1 in 20 surviving, that means the real reproduction time is 20t.
Some bacteria take 30 minutes for a single reproduction, so that with a 1/20 success rate would be an effective population doubling every 10 hours. An E. coli cell weighs 1 pg, and this is only a factor of 2^128 from the planet Mercury. These random example numbers would therefore be able to consume the entire planet in 53.32 days. At this level, almost all the time (97%) is spent on waiting for the solar panels to supply enough to get the stuff from the planet's surface to solar orbit.
> Calculated? Ok, now calculate, how much suffer probability of overall success, because limited resources does not accept to make 20 turns to achieve 1 successful?
I have no idea what point you're even trying to make here.
We know we don't need to worry about your 1/20 random example for humans because we know ourselves; only the machines need this consideration. That's a number which you made up, and your own complete fiction is what you're now trying to use for an example that I don't understand.
> Well, now I see you are just overweening human, but without real knowledge. Solar system is itself have wide parameters spectrum, but is is also significantly different from other stars environments.
Completely irrelevant. I don't even know what point you think you're making. I linked you to a specific plan to build a Dyson swarm specifically in our solar system at the orbit of Mercury. The rest of the universe is irrelevant to this part of the plan, for exactly the same reason and in exactly the same way that it is irrelevant to bacteria on Earth that the rest of the universe exists.
What you do with your Dyson swarm (including colonising the universe) only matters after you've built your Dyson swarm. Building one is fast the moment von Neumann machines can be engineered rather than grown, and give you such an incomprehensibly large industrial and resource base to work from that comparing it to what we have access to today is more extreme than asking a single pre-writing cave painter to imagine our current entire world.
> Bacteria have sacrificed billions lives, to gather information, to achieve current success rate.
So?
Yes I mean why not. If you are an expansionist advanced civ, travel is impractical and you have enought time and resources then what else is there to do?
Obviously there are explanations "why not" (as I said), but insterstellar travel unavailability is not one of them.
The data is analyzed as a dynamic system. Radar just looks at a bounce. If you setup radar incorrectly you might get false hits and no returns on valid targets. If you use a wrong model in analysis of astronomical data you're never getting anywhere close to a correct result.
The question isn't whether Dyson speheres radiate, the question is can we detect an artificial megastructure and my answer is no, based on the hypothetical Dyson design.
Other megastructures might be discovered through the same methods as exoplanets.
You mean like brown dwarfs?
R_sol^2T_sun^4 = R_shell^2T_cmb^4 (R_sol^2*(T_sun/T_cmb)^4)^(1/2) ~= 2 light months.
Could you elaborate why not? All current technology I know of has an efficiency of <100%, with waste energy being lost as heat (which in space would be radiated away in the infrared spectrum). Why would this not be the case for a hypothetical dyson sphere or swarm?
Of course everything radiates heat I did not think I have to get down to that level in commenting here.
Expansion at c is very unlikely. Insane things happen when you approach c, like the cosmic microwave background transforming into a gamma ray laser aimed at your head and collisions with microscopic particles destroying you. It may be that travel close to c is so hard as to be effectively impossible.
I’ve read that speeds up to about 30% the speed of light are “thinkable” with currently known physics plus advances like compact fusion reactors. Think something that looks like the Epstein Drive in The Expanse or the ships from Avatar.
These models provide indirect evidence against the existence of FTL travel. If FTL exists it means we really have to be extremely early, maybe even the first in our galactic cluster. Otherwise someone would have visited at least.
I also think if someone has visited, such as if some tiny number of UFOs are actually of ET origin, it means we are probably incredibly lucky to have neighbors that aren’t “reapers” in the dark forest sense. It’d be funny if our galaxy is actually full of aliens and we lucked out and are camped next to some superintelligence that is both benevolent and powerful enough to fight off anyone who isn’t. So hey if they’re taking our cattle maybe that’s a pretty small price to pay.