I only mentioned Moller’s because I was pointing out that it was not that a literal car turns into a literal airplane that we were talking about, and he has pretty pictures to demonstrate the point. I did think that he had a better track record than that as far as prototypes. I do know he hasn’t actually sold one, but last I heard, he was asking the best part of a million dollars for one. that was the first time I’d looked his project up in over a decade.
My point in that reply was only that the reason that we do not have flying cars is not because they are technologically impossible, but because they aren’t all that practical for most uses, they are expensive, and would require licenses well above what is required of normal drivers. I did not feel as though it was a reasonable comparison to the idea of asteroid exploitation, as the reasons for not adapting flying cars have nothing to do with potential bottlenecks in space development.
Sorry about the derailment. Let me refocus in what is not a direct reply to you but on the same theme.
Some of these ideas like a Dyson Sphere are very problematic from not just a technical but a political and social level.
to build a Dyson Sphere in our solar system we would have to basically take apart Mars, Venus and most of the asteroids in the asteroid belt. Even if you don’t care about the potential impact on the stability of orbits, or perturbations that may lead to far more encounters with Ort material it would be hard to get people to agree to destroying an entire planet.
Which is part of the reason that the OP’s paper was problematic to me, and I don’t need to consider their claims due to their error in process.
The assumption that intelligent life would be in a solar system with these resources, and would be willing to destroy them in the “hope” that they can reach another system is purely a thought experiment.
The deepest hole we have ever drilled is the Kola Superdeep Borehole which is 9" wide and 40,230 feet deep, so we haven’t even considered the complexities of removing all of this material down past the surface. And what do you do with the change in orbits when you do remove a significant amount of mass? Does it make the system unstable.
The assumption that it is false because we don’t see these problematic, wishful thinking structures is just not scientifically sound.
Remember that the angular momentum of the original accretion disc of our solar system has been conserved, and making massive changes to those systems, which are at a lower energy state is not a trivial topic.
I am glad that people are thinking up these crazy ideas, but they are crazy ideas and not even close to being possible let alone practical.
I agree with Bricker. There are only about 5,000 years separating our (relatively) advanced technological civilization from a civilization that was primitive and hardly detectable by today’s standards. To say that there can’t be other more advanced civilizations is unreasonable. Only 500 years or so separate the “great” Spanish fleet of wooden ships and cannons from the United States’ 7th fleet with its awesome array of modern weapons and jets. How much of a difference, then, would 25,000 years be?
And what if we didn’t build a Dyson sphere? the sphere idea got caught up in Sci-Fi, and so for some reason has become what the public thinks of, but that was never a proposed idea. The idea is a Dyson swarm. A bunch of little (comparatively) solar collectors and reflectors that slowly dim the star’s light until at some point, you have managed to cover it all. This is not an all at once thing, and the asteroids alone will give a pretty good start. No need for dismantling planets.
Once again, not something that is actually proposed. The idea would be that they would be using the resources of their solar system, and over time, would find themselves closer to another star than their home star. This is not a civilization with goal of reaching another system, this is just the basic and natural consequence of growth. Maybe a few groups would take it upon themselves to head out to another system, to get ahead of the crowds, but this would be, once again, not a solar system wide project,but one that would be done piecemeal and individually.
40,230 feet deep is deeper than many asteroids are long. It’s much much easier, in fact, to drill into an asteroid than into the Earth’s surface. (once you have the appropriate technologies and engineering in space, of course.)
As far as instability, not really. Short of removing Jupiter, I doubt that there would be any issues of stability in orbits. And even that wouldn’t really cause problems over the short term, and the long term, if we can do things like remove Jupiter, then any orbital instabilities would be trivial to correct.
But, that is only because you are thinking of the problematic, wishful thinking structures that you have been exposed to with sci-fi, and not the actual structures being proposed.
That doesn’t really matter. Everything will be staying in roughly similar orbits that it is in now. Only if you were making one of the sci-fi structures that have been already discarded decades ago would that be an issue.
Starting with the basics of extracting useful materials from asteroids to the point of inhabiting asteroid based colonies that end up being really far out there, so far out that you are closer to another star, where are the ideas too crazy to be possible or even practical?
Similar structures have similar energy/resource needs, and note the paper Kardashev scale, which demands a Dyson sphere to reach Type II, and type I is highly likely to be unreachable.
The original paper used:
“The G-survey established that there were no type III Kardashev civilizations using more than 85 % of the starlight in 105 surveyed galaxies[28].”
Which requires type II at some point and it is a lot of what they used for their Bayesian priors.
The Entire Kuiper belt (including Pluto) is ~ 1/25 - 1/10 Earth Masses spread over 20 AU. The Asteroid belt is 20 to 200 times smaller then that. While it may be usable for small quantities or high value materials, collecting it is still very energy and time intensive. But note that the entire Kuiper belt is ~10 Earth moons.
The material required to reach anywhere close to a type II will demand destruction of Mars and Venus, there just isn’t enough material
No I am thinking of a paper that made a claim, which used concepts which would require civilizations to harness at least a significant portion of their stars energy output to be detectable, then use the fact that we haven’t detected that to set up a Monty Carlo simulation that said that the chances of life in the universe are small.
I think the problems with highly charged particles, and required energy resources are going to be blockers for any interstellar spread from a location. If someone is going to reference the Kardashev scale when trying to count probabilities it is on them to justify that even a type I is possible. My criticisms directly point at the SciFi scenarios that these individuals used.
The claims such as:
“Galactic settlement timescales have been estimated to be below 10^6 yr to 10^10 yr, with most estimates on the order of 10^7 yr”
Note they are assuming 10^7 when the milky-way is 10^5 light years across. This forces an assumed model where travel rates are highly energy intensive. Remember that gravity assist velocities are relative to the sun, and the velocity doesn’t change at all from the perspective of the boosting planet. The implications are that even if you can get a cheap ride out of the solar system, you will need to carry a propulsion source to slow you down on the other side. You lose the free return benefit that lets us visit local bodies.
The entire hope and dream of galactic settlement, and thus high energy radiation that will be detectable (or observed Dyson Spheres) is what requires the SciFi mindset. A slow, chemical rocket rate trip to even our closest neighbor, Proxima Centauri would take ten of thousands of years at reasonable, reversible velocities.
So even if you dismiss the original papers claims, you will have to figure out how to sustain a small population, and protect them from cosmic rays for at least several times longer than we have even had agriculture. And i twill take a large portion of the output of that group to do so thus it may just not be practical at all.
With the increasing information about how common the building blocks for life are in the universe is is pretty insane to think that we are alone, and to dismiss that concept because of the above wishful SciFi like claims is absurd.
Note that this is entirely consistent with the published literature on the Fermi Paradox, rather than science fiction; if you want to change the distribution of these estimates then you could always publish some estimates of your own.
Many of these estimates don’t take much notice of the problems involved in moving humans between stars, since they tend to consider self-replicating autonomous probes rather than breeding populations.
The least massive Dyson Shell concept is a statite bubble, a light-supported structure which would mass about the same as the asteroid Pallas. I’d prefer something a bit weightier, simply because a statite bubble couldn’t retain much of the incident energy without melting. But it does indicate that you needn’t disassemble every body in the Solar System (at least, not straight away).
And if the conditions happen, and if you subscribe to information theory, the (apparent) paradox between the second law of thermodynamics and the high degree of order and complexity produced by living systems melts away. Entropy isn’t Disorder it is complexity or information and life can be considered a natural outcome in that process.
But self-replicating autonomous probes would have a similar potential of being energy limited. Plus I am skeptical after building my own 3D printer from scratch (including mechanically etched circuit boards) that the eternal self replication model is practical.
The available resources and other constraints will also limit self replicating machines just as it does with self replicating DNA.
Consider the asteroid model, once you are out of the Earth’s atmosphere the energy costs of getting to them is reduced, but once you are at one location even moving to another neighboring asteroid will require significant energy.
Remember that they are far enough apart that NASA doesn’t even worry about missing them when sending probes through. So you would have to do a Hohmann transfer to a different orbit, have several phasing passes then have another Hohmann transfer to the other asteroid.
Waiting for a gravity assist path would require a lot less energy to be carried around but would greatly slow the progress. And once again to go outside of the local system will result in an almost quadratic increase in fuel storage to decelerate on the other end.
I am glad people are working on this, but it is all Science Fiction at this point. The most real part about the subject at all is that life probably does exist wherever the conditions allow for it.
It does not demand a dyson sphere. No one demands a dyson sphere. Everyone involved knows that a dyson sphere is impractical to build, live in, maintain, and is not orbital stable.
A dyson swarm, on the other hand, a a completely different thing. When you think of a dyson sphere, yo are thinking of a solid shell around the star, at least thick enough to carry its own weight.
A dyson swarm is multitudes of much smaller statites and orbital collectors. The vast majority of the surface area would be only a few molecules thick.
And the point of the paper was to show that there didn’t seem to be any type III civs out there. A type III would be a natural outgrowth of a II over the course of at most millions of years. That we don’t see any galaxies like this gives some indications as to what is out there.
Only if you are building some sort of solid sphere, rather than many, many small collectors and reflectors.
The different types are not robust classifications, but just an estimate of how much energy the civ has access to. The idea that we could use all the energy avail be to us provided by our planet doesn’t seem far fetched at all.
They make no such assumption. They gave a range, and that range goes up 3 orders of magnitude higher than what you say that they assume. Galaxies are of different sizes, some being relatively tiny.
In any case, the 10^7 years only implies a propagation at 1% the speed of light. At 10^10, that is only .001% the speed of light.
Well, we are not far off from developing technologies much better than chemical. We currently have ion drives, that are much better, and there are other concepts that could give even better ISP. And, though you cannot use a gravity slingshot off the sun, the oberth effect still works.
Doesn’t need to be all that small a population, and doesn’t need to be that hard to protect. Build the whole thing into an asteroid. As you travel, you mine the asteroid for expansion materials and replacements for lost recyclables.
Add to that that you don’t even need to deliberatly travel to another solar system. You keep pushing out further and further into the oort cloud, and eventually, you find that you are actually in the oort cloud of another star. Then you work your way in from there.
It would only be a few adventurous colonies that decide to skip over the slow expansion, and go out deliberatly to other stars to get ahead of the wave of growth behind them. Some may make it, some won’t.
We don’t really know. We have yet to have determined that life arose anywhere but earth. I think it probably has, I think that life is probably pretty common. But that’s different from intelligent life, and that is very different from space faring life.
Th things that you are assuming are scifi like, but the things that I am talking about are entirely different, and are much more practical. To assume that space faring life is common, but that not a single one of them went down the path of building orbital solar collectors is what I consider to be absurd.
Which is lighter than any material we have found by about a factor of 4, and will need to be much stronger.
It is questionable under material science, but cannot yet be ruled out.
That shift in the burden of proof is an example on why this is “Science Fiction”
There aren’t even materials on the horizon that will work under that model, as graphene would absorb too much radiation.
I’ll give the idea more credence when they can actually build one. And account for the manufacturing material and energy needs.
Even if sourcing and transporting materials wasn’t an issue, WAG (not reliable at all) math shows 100s of years of earth entire energy output to even make the graphine (if they could make large sheets)
If life is common, or even rare; intelligent life is just a statistical happenstance. Conditions just need to be right for the use of tools to a crucial evolutionary advantage over the energy budget that it costs. Even if that evolutionary advantage is due to limitations of past evolution.
There is no need to resort to massive public works collecting insane amounts of energy to be noisy enough for us to see here.
There are very few n-body simulators that don’t end up throwing some planets out of the solar system after a few million years. The solar system as is only seems stable for a few tens of millions of years before chaotic stuff starts happening in simulations.
In any case, if we actually do start taking apart planets, (which is something that we don’t need to do), then we have more than enough technology and energy at our disposal that if anything starts going off in an odd direction that we don’t like.
I’m not sure what there is to accept. There are lots of stars and planets, and there is no evidence of alien life. That’s all the paradox is.
That’s only a paradox for young earth creationists. Everyone else knows that the earth is not a closed system, it gets energy from the sun.
We been doing it for over 4 billion years.
No real need for fully automated replicating machines, and in fact, quite a few reasons why they are not the best idea.
Not really. Far, far less than just getting into low earth orbit. Getting from one asteroid to another could take as little as a few hundred meters/s of delta V. If you don’t mind waiting a bit, you can use even less.
Just because they are far apart doesn’t mean that they are hard to get from one to the other. You wouldn’t be using Hohmann trajectories, that’s really only used when you are going between planets, not between asteroids that share common orbital parameters.
You wouldn’t need gravity assist paths to get between asteroids. And, in any case, there wouldn’t be all that much need for people to go between asteroids, most of what little cargo there would be would be raw materials and other stable products, where you don’t really care how long it takes, just like cargo ships on the seas of today.
At least at the end, you agree that it is Science Fiction, rather than SciFi. Yes, these are technologies that have not yet been deployed, but they do not break any laws of physics.
The point there is that with that, we can make the whole thing with a tiny fraction of the materials available to us. If we make it 4 times, or even 40 times thicker, we still don’t need to dissemble planets.
All the more reason to increase the amount of energy we have at our disposal.
Once again, not a massive public works project. A single company that is making products, like graphene, for use could have thousands of square miles of solar collectors in orbit.
And it is not that we would be making noise, it would be that we are dimming the sun, something that is noticeable from far away.
And, keep in mind, we are not just talking about us. We are talking about the galaxy and the universe. We are talking about all the other forms of life that may have arisen. That space faring life is common, but not a single one of them builds large solar collectors in orbit strikes me as unlikely.
If your argument is that space fairing life is rare, then I’d agree. If your argument is that space fairing life is common, where are they?
Let me know when that happens and you can reach 0.1 c
As of this date New Horizons probe, post boost only reached 0.0000536 c.
But you may want to do the math on the Ion thrusters, you will have to be decelerating for at least 50% of the trip, and that is a real bummer for total travel time.
Also remember that Dawn spacecraft with an Ion thruster, reached a velocity of 10 km/s with 74 kilograms of xenon but the delta was only 4.3 km/s.
You are talking about getting to ~29970 km/s, then stopping from there too in order to reach 1% of c.
The 8x improvement in efficiency over chemical rockets is almost completely lost in the orders of magnitude.
Why would I do that, as I said that you could get their figures with .00001C, which is only a few miles per second. Very attainable.
Yeah, about 10 miles per second.
No, you would accelerate for a time at the beginning, then decelerate towards the end, coasting for the majority of the time. A continuous burn is the least effeteness way of getting anywhere.
Yes, a prototype, launched from earth with only the bare minum it needed to accomplish its mission.
Please tell me where I am talking about getting to ~29970km/s.
Try plugging that 8x improvement in efficiency into the rocket equation, and see what a difference it actually makes.
You do realize that Polyacrylonitrile the precursor for 90% of high quality carbon fiber production, and the commercial source is made from propylene and ammonia from natural gas? And that the energy costs limit the world supply so much that when Boeing decided to use it in their planes that other industries had to make faux versions because the cost rose so high.
I am not trying to ruin the space exploration idea, but to put it as the test as far as the possibility that there is life in other parts of the universe is ridiculous.
There are lots of reason even intelligent forms of life wouldn’t, or couldn’t follow this path.
Heck right now we don’t know if we could. And to go back to bayesian priors, I have data that unlimited energy consumption typically doesn’t end up being good. High quality carbon, for carbon fiber currently takes 800 MJ/kg to produce. Even without getting it off a planet the numbers are huge.
Heck, it makes sense to go with the null on this until you can describe what you are going to do with all the waste energy you produce.
The search for life shouldn’t be limited by pipe dreams, and that is not making a judgement on if people should have pipe dreams or not.
Once again, dream away but the generally accepted reality is that even a dyson swarm is beyond or abilities.
And NONE of this is required for there to be intelligent life. Heck I could make an argument that hoping for eternal exponential growth is a good indication that we may not hit the bar with other forms of ‘intelligent life’. I could also make that argument for producing self-replicating mechanical viruses for what? To serve our vanity that things we made spread across the galaxy?
Note that while it may not be perfect, the fact that Cephalopods, Corvids and Primates developed *intelligence[/] separately from our shared ancestor demonstrates that it is not as novel as people claim.
Really, nothing you have given me moves me away from the Null, which once again is why this isn’t Science “yet”.
Can’t the need for propellant when decelerating on approach to a system be eliminated with some sort of magnetic sail? And can such sails be operated with minimal energy as long as there’s a way to bleed off electrons and charge the sails? (I hope so — this is what I use in my sci-fi epic.)
:eek: Was the great discoverer of gravitation, after all, correct all along?