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Advanced technological civilizations do not communicate across interstellar distances because you can never get off the first page of Encyclopedia Galactica. This discussed more in my paper from the OSETI III conference, Life at the limits of physical laws which is part of the Matrioshka Brains papers.

We can conduct "SETI" (where the emphasis is searching for 'signs' of advanced technological civilizations) but it requires gravitational microlensing studies, infrared and occultation astronomy -- not listening for radio or optical transmissions.

The fact that we are accelerating towards the Vinge Singularity is ignored. Kurzweil is extensively documenting this at KurzweilAI.net (unavailable today). Various estimates place this between 2020 and 2050. Once we have autonomous self-replicating systems (nanobots), we can dismantle the planets and turn it into computronium. We will come very close to the limits of the computational capacity allowed within our solar system within this century. Even if this fast ramp is not realized, you underestimate the progress that will be made in extending the human lifespan. We have the genome now, we will rapidly decode much of it over the next decade and begin to design and implement anti-aging therapies. Unless you are over 50 years old or will reject the use of such technologies, the probability that you will make it to 200 is quite high. Sorry, you have to face the problem. :-)

The fact that we are accelerating towards the Vinge Singularity is ignored. Kurzweil is extensively documenting this at KurzweilAI.net (unavailable today). Various estimates place this between 2020 and 2050. Once we have autonomous self-replicating systems (nanobots), we can dismantle the planets and turn it into computronium. We will come very close to the limits of the computational capacity allowed within our solar system within this century. Even if this fast ramp is not realized, you underestimate the progress that will be made in extending the human lifespan. We have the genome now, we will rapidly decode much of it over the next decade and begin to design and implement anti-aging therapies. Unless you are over 50 years old or will reject the use of such technologies, the probability that you will make it to 200 is quite high. Sorry, you have to face the problem. :-)

You do need to save the intermediate state information. That is why Frank's design for the ultimate reversible computer is so big (see my other post on this topic). You should keep in mind that you can compute for "free" (if you do it slowly), its erasing bits that costs you money (generates entropy as heat). Logical AND operations erase information such that you cannot run the calculation backwards. You have to design the hardware such that it has no such information destroying operations.

You do need to save the intermediate state information. That is why Frank's design for the ultimate reversible computer is so big (see my other post on this topic). You should keep in mind that you can compute for "free" (if you do it slowly), its erasing bits that costs you money (generates entropy as heat). Logical AND operations erase information such that you cannot run the calculation backwards. You have to design the hardware such that it has no such information destroying operations.

It is worth noting that Lloyd's thought experiments in these areas were preceded by similar speculations over 4 years ago in Anders Sandberg's paper The Physics of Information Processing Superobjects: Daily Life Among the Jupiter Brains. Lloyd has extended them a bit by bringing Black Holes into the picture.

Now, what we will be able to engineer in this century, using diamondoid molecular nanotechnology, is solar system sized nested layer Dyson shell supercomputers. This is a unique architecture that I have named a Matrioshka Brain. It will allow us to most efficiently use the entire power output of the sun and compute somewhere in the range of 10^42 to 10^52 ops per second.

Interestingly enough, Michael Franks has a paper "Reversibility in optimally scalable computer architectures" which postulates a solar system sized reversible architecture that would out-compute any non-reversible architecture. This too would be using atomic-scale engineering. Unfortunately it requires the power output of an A or B class star (~50,000 suns) and requires an amount of silicon equal to the mass of Saturn (our solar system doesn't even come close to having that unless we mine the sun for it). After we have developed machines of these architectures, our development comes to a slow halt unless our ability to do sub-atomic engineering can be developed. I'll be quite happy with what we can get out of atomic-scale engineering -- it supplies enough computronium for roughly a trillion-trillion human minds for those who choose to upload.

It is worth noting that Lloyd's thought experiments in these areas were preceded by similar speculations over 4 years ago in Anders Sandberg's paper The Physics of Information Processing Superobjects: Daily Life Among the Jupiter Brains. Lloyd has extended them a bit by bringing Black Holes into the picture.

Now, what we will be able to engineer in this century, using diamondoid molecular nanotechnology, is solar system sized nested layer Dyson shell supercomputers. This is a unique architecture that I have named a Matrioshka Brain. It will allow us to most efficiently use the entire power output of the sun and compute somewhere in the range of 10^42 to 10^52 ops per second.

Interestingly enough, Michael Franks has a paper "Reversibility in optimally scalable computer architectures" which postulates a solar system sized reversible architecture that would out-compute any non-reversible architecture. This too would be using atomic-scale engineering. Unfortunately it requires the power output of an A or B class star (~50,000 suns) and requires an amount of silicon equal to the mass of Saturn (our solar system doesn't even come close to having that unless we mine the sun for it). After we have developed machines of these architectures, our development comes to a slow halt unless our ability to do sub-atomic engineering can be developed. I'll be quite happy with what we can get out of atomic-scale engineering -- it supplies enough computronium for roughly a trillion-trillion human minds for those who choose to upload.

It is most unfortunate that yet another individual wasn't prepared for a premature death. Someone with this his education and technical awareness should certainly have been signed up for cryonics. For readers who want to call that crazy, don't hit the submit key until you have read the the detailed commentary by Ralph Merkle on how molecular nanotechnology may be used to repair the damage caused by freezing. Be informed and be prepared or be dead. Its pretty simple logic. It is very sad that Douglas Adams wasn't informed enough and smart enough to follow this path. Until Mind Uploading becomes feasible, cryonics is the only viable option we have available defeating death.

I would be curious to see information on these designs. Certainly with such a design one could leave the solar system (although it would take an awfully long time to get to another star...).

Google says that Drexler's "lightsail" paper is at http://www.aeiveos.com/~bradbury/Authors/Engineeri ng/Drexler-KE/MMfSSAO.html, but I'm having difficulty getting the page to load right now (try Google's cache). Anyway, Drexler writes "A 20 nm thickness of aluminium has a reflectivity approaching that of the bulk material (~ 0.9). Lightsails constructed on the multikilometre scale can have structural masses that are small compared to the reflector mass, if a suitable pure-tension structure is employed to transmit forces from the sail to the payload. At Earth's distance from the Sun, the outward acceleration of an unloaded sail using 20 nm aluminium reflectors is ~0.16 m/s^2, or ~ 14 km/s per day." The acceleration of the Sun's gravity at Earth is only 0.0059 m/sec^2, unless I slipped a decimal point.

I'm looking but haven't found any helpful info on the Halley rendezvous probe, but what you're describing sounds like the probe would slingshot around either a planet or the comet itself...

1. Thrust out and change plane to get into the plane of Halley's orbit.
2. From the top of this ellipse, thrust back to get into a very elliptical retrograde orbit.
3. Fall in toward the Sun, edge-on to minimize thrust.
4. Once past perihelion, thrust to match velocities with the comet which is just about to come by.

However, if you wanted to leave the solar system, it seems unlikely that you could get enough energy for it by slingshotting around planets...

My suspicion would be that after the human, mouse & fugu are finalized that the next genome to sequenced will be the Chimpanzee. Then the question is -- what genomes do you sequence after those? I've argued that since aging is the disease that everyone has, that genomes of non- or slowly aging organisms would provide a great deal of information about what improvements need to be made to the human genome to allow us to live indefinately (longvity limited by our accident rates). The genomes that would provide interesting insights include elephants, whales, tortises, lobsters, giant clams, bats and parrots or maccaws. The genomes of all of these species have been tuned for extended longevity, perhaps in quite different ways. The genomes of species such as geckos, starfish, crabs and other animals that have the ability to regrow limbs would provide us with information on how nature has organized genetic programs to regrow complex tissues (something humans lack). Those who would like to push the NIH in this direction should send letters about this to the Office of the Director of the NHCGR. See this link.

For those interested, I maintain a page with a semi-current status of many of the genome projects here.

The Hong and Mirkin reference is:
S. Hong and C. A. Mirkin, "A Nanoplotter with Both Parallel and Serial Writing Capabilities", Science 288(5472):1808-11 (9 Jun 2000).

We have two space habitats now, MIR and the International Space Station. The history of the development of space habitats shows that, using current technology, we produce very high cost habitats that are dependent upon the Earth. O'Neill in his promotion of real space habitats makes it clear that to be built cost effectively, the material for their construction must come from someplace other than the Earth. That requires future technology.

Given current habitat dependence on earth, a civilization destroying asteroid, would presumably doom the crews on the station(s) as well. If the impact is not too large (sufficiently large to vaporize the oceans), then we should expect crews in submerged nuclear submarines to survive. Because they have long life power sources and extensive food stores, they would presumably be able to emerge someplace where even longer term energy resources are available (e.g. the Middle East). This would potentially allow them to construct green houses that could support a small population until the dust clears from the atmosphere. There are possible locations (deep valleys, underground facilities, etc.) that could survive the impact as well. Collectively, these would form the seeds of a new civilization. There are of course problems such as how do you identify locations where there are likely to be preserved the seeds, power sources, light sources, etc. in relative proximity that would allow you to maintain an agricultural base. But I think people could figure this out. It would be interesting to start a project that created a number of protected "humanity shelters" around the world that were widely know about just to be able to know we had a solution to the most probable doomsday scenarios.

Now, with regard to moving extensive numbers of people into space habitats or colonizing other planets with self-sustaining groups. This is going to require nanotechnology to be done cost effectively. If you have self-replicating systems based on nanotechnology (discussed by Josh Hall in this paper), then you can rapidly move people off the planet. You can also dissassemble a planet or two and build in the vicinity of ~100 billion telescopes the diameter of the moon. This array of telescopes would fill most of the inner solar system out to the orbit of Jupiter. At that point we would certainly be able to identify all of the Oort Cloud objects. Nanoprobes would then be launched to these objects using mass drivers. Once they arrive at these objects, they can be disasssembled into useful construction material and reoriented on orbits to deliver that material to useful locations. If objects were found that were on killer trajectories that could not be reformatted/redirected in time by the nanoengineers, then the mass drivers could also be used to deliver high velocity projectiles into the oncoming path of the object to deflect or vaporize it.

So the answer, as it is with most things, is we need molecular nanotechnology and self-replicating engineering systems. The last time I looked at some of the sites suggested, they did not include nanotechnology in their habitat development strategies. Without nanotechnology, the costs are likely to be so high that serious people can only consider them fantasies.

We have two space habitats now, MIR and the International Space Station. The history of the development of space habitats shows that, using current technology, we produce very high cost habitats that are dependent upon the Earth. O'Neill in his promotion of real space habitats makes it clear that to be built cost effectively, the material for their construction must come from someplace other than the Earth. That requires future technology.

Given current habitat dependence on earth, a civilization destroying asteroid, would presumably doom the crews on the station(s) as well. If the impact is not too large (sufficiently large to vaporize the oceans), then we should expect crews in submerged nuclear submarines to survive. Because they have long life power sources and extensive food stores, they would presumably be able to emerge someplace where even longer term energy resources are available (e.g. the Middle East). This would potentially allow them to construct green houses that could support a small population until the dust clears from the atmosphere. There are possible locations (deep valleys, underground facilities, etc.) that could survive the impact as well. Collectively, these would form the seeds of a new civilization. There are of course problems such as how do you identify locations where there are likely to be preserved the seeds, power sources, light sources, etc. in relative proximity that would allow you to maintain an agricultural base. But I think people could figure this out. It would be interesting to start a project that created a number of protected "humanity shelters" around the world that were widely know about just to be able to know we had a solution to the most probable doomsday scenarios.

Now, with regard to moving extensive numbers of people into space habitats or colonizing other planets with self-sustaining groups. This is going to require nanotechnology to be done cost effectively. If you have self-replicating systems based on nanotechnology (discussed by Josh Hall in this paper), then you can rapidly move people off the planet. You can also dissassemble a planet or two and build in the vicinity of ~100 billion telescopes the diameter of the moon. This array of telescopes would fill most of the inner solar system out to the orbit of Jupiter. At that point we would certainly be able to identify all of the Oort Cloud objects. Nanoprobes would then be launched to these objects using mass drivers. Once they arrive at these objects, they can be disasssembled into useful construction material and reoriented on orbits to deliver that material to useful locations. If objects were found that were on killer trajectories that could not be reformatted/redirected in time by the nanoengineers, then the mass drivers could also be used to deliver high velocity projectiles into the oncoming path of the object to deflect or vaporize it.

So the answer, as it is with most things, is we need molecular nanotechnology and self-replicating engineering systems. The last time I looked at some of the sites suggested, they did not include nanotechnology in their habitat development strategies. Without nanotechnology, the costs are likely to be so high that serious people can only consider them fantasies.

See: Misconceptions Regarding SETI, Dyson Spheres and the Fermi Paradox

The bottom line is this -- nanotechnology enables the transition from pre-Kardashev-Type-I civilizations (us) to post-KT-II civilizations in decades. Such civilizations are resistant to almost all hazards on galactic scales and will thus be the dominant form of life in galaxies. If we are typical, it only takes a few hundred years to evolve from the discovery of the laws of physics to reach KT-II levels. KT-II civilizations survive for trillions of years. Unless the evolution of intelligent life is very, very difficult our galaxy should be dominiated by KT-II civilizations (Dyson shell supercomputers, a.k.a. Matrioshka Brains) with thought capacities in excess of a trillion trillion times the human mind.

Intentional communications generally occurs between entitites of approximately the same capacity. As we are at the sub-worm level in comparison to KT-II civilizations, they will not be directing communications at us. Non-intended leakage communications could be detected by SETI out to a few dozen light years, but we should be looking in the MHz frequences, not in the GHz frequencies. Therefore SETI@home is a waste of CPU cycles.

Interstellar travel is possible (the British Interplanetary Society Project Daedalus Study showed that). It is however pointless. The speed-of-light delays and communications costs for large volumes of data, mean you get little benefit from colonization. You do not want to become larger, you want to become smaller (or at least work very hard to minimize propagation delays)! The fact that KT-II civilizations can each build billions of lunar diameter telescopes makes rationalizations for interstellar travel difficult (why go "there" when you can "watch" there?). You also don't go very far, because "there", by the time you arrive, may not be there anymore (a closer civilization may have occupied the location). Arguments that we should colonize the galaxy in a few million years fail to understand that the rate of expansion is not limited by the speed-of-light but by the time it takes to dismantle planets, gas giants, brown dwarfs, etc. and turn them into something useful. It isn't the stars that are desirable to KT-II civilizations, it is planets with heavy metal abundances that "happen" to be on courses around the galaxy that these civilizations find attractive.

It is worth noting that the gravitational microlensing results, suggest that our galaxy is surrounded by ~200 billion "objects" of masses around 0.3-0.5 Msun. Astronomers are currently unable to provide an good explanation for what these might be. The best current guess is primordial black holes. (Of course most of the astronomers involved assume the universe is "dead".)

Comments by Verteiron, regarding the use of radio are absolutely correct. Given the capacities of KT-II civilizations, they are going to be able to build very large telescopes that can detect any other KT-II civilizations. If they want to communicate, they will do it using tightly focused lasers, probably in the blue or UV regions. This minimizes photon (energy) loss due to beam spreading and allows the highest data rates.

The problems mentioned by Bill Joy in his interview point out how poorly informed he is. Anyone who has been in the computer industry as long as he has, should know enough to "read the manual(s)" before offering uninformed opinions. The problems regarding nanotechnology run amok have been discussed for many years in the sci.nanotech newsgroups as well as at conferences for the Foresight Institute's Senior Associates. The basic solutions involve making "safe" (e.g. reviewed, open source) designs available while at the same time developing defenses against nanotech run amok. The Extropy Institute's Mailing List Archives, for example, contains recent discussions about encouraging the availability of "almost anything" manufacturing boxes (similar to Star Trek "replicators"), while discouraging the availability of "everything" boxes.

Diamondoid or saphire based molecularly assembled nanobots used in medical applications will greatly exceed the capabilities in of "biobots" built on existing genetic machines (DNA, enzymes, bacteria, cells, etc.) because they are stronger, can pack the "code" more densely, and can have more complex programs than the rather "ad hoc" designs that nature has provided us with. Most of the first volume of Nanomedicine is devoted to determining exactly what the physical limits will be on power, communication, mobility, etc. Most of the applications will be discussed in Volumes II and III.

Joy may be right that the technology poses a threat to the "human species", but that begs the question of "Why would you want to run on obsolete hardware?". Anyone who understands even a little astronomy knows that galactic hazards doom biological human forms to death at some point. Only those humans who choose to upload have any hope of living the trillion or so years that seems quite feasible. So while the hopes for biochemical humans are rather dismal even with Nanomedicine, the long term prospects for humanity, based on what nanotechnology allows are quite good indeed.

As far as nanotechnology background material goes, the best (nontechnical) source is Engines of Creation. Other references can be found in Eric Drexler's CV.

While commenting on some problems regarding SETI searches, I provide a discussion of how O'Neill's colonies might be updated using biotechnology and nanotechnology. Steel and aluminium are terrible structural materials compared with diamond, buckytubes and sapphire. The combination of the short replicating times allowed by nanoscale self-replicating systems and the material properties of the strongest materials will allow us to rapidly go far beyond O'Neill's vision -- to the point of dismantling entire planets.

Government support or programs is not required to do this. Molecular Nanotechnology of the type being developed by Zyvex is required. In addition, we need the designs for the nanobots to take apart the asteroids or planets, construct the mass drivers and solar arrays, etc. The lack of molecular designs, is discussed in the Nano@Home proposal. Because we will be able to do the designs at home, a small dedicated group will eventually be able to bootstrap the development of space and achieve the vision O'Neill described. Because of the rapid increase in the available resources (matter and energy) per person, the large number of people living in poverty should disappear as well. The only potential problem I see is if Mind Uploading becomes feasible (or real AIs are developed) and unlimited copying of such entitites is allowed. This has been explored in more detail by Robin Hanson in If Uploads Come First.

While commenting on some problems regarding SETI searches, I provide a discussion of how O'Neill's colonies might be updated using biotechnology and nanotechnology. Steel and aluminium are terrible structural materials compared with diamond, buckytubes and sapphire. The combination of the short replicating times allowed by nanoscale self-replicating systems and the material properties of the strongest materials will allow us to rapidly go far beyond O'Neill's vision -- to the point of dismantling entire planets.

Government support or programs is not required to do this. Molecular Nanotechnology of the type being developed by Zyvex is required. In addition, we need the designs for the nanobots to take apart the asteroids or planets, construct the mass drivers and solar arrays, etc. The lack of molecular designs, is discussed in the Nano@Home proposal. Because we will be able to do the designs at home, a small dedicated group will eventually be able to bootstrap the development of space and achieve the vision O'Neill described. Because of the rapid increase in the available resources (matter and energy) per person, the large number of people living in poverty should disappear as well. The only potential problem I see is if Mind Uploading becomes feasible (or real AIs are developed) and unlimited copying of such entitites is allowed. This has been explored in more detail by Robin Hanson in If Uploads Come First.

While commenting on some problems regarding SETI searches, I provide a discussion of how O'Neill's colonies might be updated using biotechnology and nanotechnology. Steel and aluminium are terrible structural materials compared with diamond, buckytubes and sapphire. The combination of the short replicating times allowed by nanoscale self-replicating systems and the material properties of the strongest materials will allow us to rapidly go far beyond O'Neill's vision -- to the point of dismantling entire planets.

Government support or programs is not required to do this. Molecular Nanotechnology of the type being developed by Zyvex is required. In addition, we need the designs for the nanobots to take apart the asteroids or planets, construct the mass drivers and solar arrays, etc. The lack of molecular designs, is discussed in the Nano@Home proposal. Because we will be able to do the designs at home, a small dedicated group will eventually be able to bootstrap the development of space and achieve the vision O'Neill described. Because of the rapid increase in the available resources (matter and energy) per person, the large number of people living in poverty should disappear as well. The only potential problem I see is if Mind Uploading becomes feasible (or real AIs are developed) and unlimited copying of such entitites is allowed. This has been explored in more detail by Robin Hanson in If Uploads Come First.

While commenting on some problems regarding SETI searches, I provide a discussion of how O'Neill's colonies might be updated using biotechnology and nanotechnology. Steel and aluminium are terrible structural materials compared with diamond, buckytubes and sapphire. The combination of the short replicating times allowed by nanoscale self-replicating systems and the material properties of the strongest materials will allow us to rapidly go far beyond O'Neill's vision -- to the point of dismantling entire planets.

Government support or programs is not required to do this. Molecular Nanotechnology of the type being developed by Zyvex is required. In addition, we need the designs for the nanobots to take apart the asteroids or planets, construct the mass drivers and solar arrays, etc. The lack of molecular designs, is discussed in the Nano@Home proposal. Because we will be able to do the designs at home, a small dedicated group will eventually be able to bootstrap the development of space and achieve the vision O'Neill described. Because of the rapid increase in the available resources (matter and energy) per person, the large number of people living in poverty should disappear as well. The only potential problem I see is if Mind Uploading becomes feasible (or real AIs are developed) and unlimited copying of such entitites is allowed. This has been explored in more detail by Robin Hanson in If Uploads Come First.

While commenting on some problems regarding SETI searches, I provide a discussion of how O'Neill's colonies might be updated using biotechnology and nanotechnology. Steel and aluminium are terrible structural materials compared with diamond, buckytubes and sapphire. The combination of the short replicating times allowed by nanoscale self-replicating systems and the material properties of the strongest materials will allow us to rapidly go far beyond O'Neill's vision -- to the point of dismantling entire planets.

Government support or programs is not required to do this. Molecular Nanotechnology of the type being developed by Zyvex is required. In addition, we need the designs for the nanobots to take apart the asteroids or planets, construct the mass drivers and solar arrays, etc. The lack of molecular designs, is discussed in the Nano@Home proposal. Because we will be able to do the designs at home, a small dedicated group will eventually be able to bootstrap the development of space and achieve the vision O'Neill described. Because of the rapid increase in the available resources (matter and energy) per person, the large number of people living in poverty should disappear as well. The only potential problem I see is if Mind Uploading becomes feasible (or real AIs are developed) and unlimited copying of such entitites is allowed. This has been explored in more detail by Robin Hanson in If Uploads Come First.