4 ms·

I find that reading huge numbers doesn't get the true scale across. It helps to bring the relative scale down to human terms. There are 63,360 inches in a mile.

I find that reading huge numbers doesn't get the true scale across. It helps to bring the relative scale down to human terms. There are 63,360 inches in a mile. There are about 63,240 AUs in a light-year. So if the Earth was one inch from the Sun, Alpha Centauri would be 4 miles away. In this miniature model, the speed of light is around 7 inches per hour, or 1 mile per year, and our fastest probes take 100 days to move an inch. The galaxy sounds big at first, but only because our lives are so short. If we built Von Neumann probes we could take over the galaxy in a mere million years. That's nothing on a geologic time scale. The fact that the solar system has sat around for 4 billion years without being eaten by Von Neumann machines makes me pretty certain that we're alone.

robryan 16y ago
What if most civilisations either destroy themselves or are wiped out by a comet or changing star conditions or an irregular orbit, or any number of things. If life truly does take as much time to become intelligent enough to actually tackle space travel there is a lot that can go wrong in the 4 billion year interim. Plus that requirement rules out a great number of stars which don't live long enough. Even our civilisation, any number of things could still go wrong before we are able to explore the universe. I wouldn't be surprised if we find a decent amount of life of the single cell variety. There is also the possibility of a civilisation far older than ours that never really got going on the intelligence path, or are lacking a good supply or certain base materials to really get going.
eru 16y ago
Please read `Burning the Cosmic Commons: Evolutionary Strategies for Interstellar Colonization' (http://hanson.gmu.edu/filluniv.pdf http://hanson.gmu.edu/filluniv.pdf) from the wonderful collection `The Economics of Science Fiction' (http://hanson.gmu.edu/econofsf.html http://hanson.gmu.edu/econofsf.html). The paper provides an explanation for us not having seen those probes that still allows other civilizations to exist. From the abstract: "Attempts to model interstellar colonization may seem hopelessly compromised by uncertainties regarding the technologies and preferences of advanced civilizations. If light speed limits travel speeds, however, then a selection effect may eventually determine frontier behavior. Making weak assumptions about colonization technology, we use this selection effect to predict colonists' behavior, including which oases they colonize, how long they stay there, how many seeds they then launch, how fast and far those seeds fly, and how behavior changes with increasing congestion. This colonization model explains several astrophysical puzzles, predicting lone oases like ours, amid large quiet regions with vast unused resources."
CamperBob 16y ago
The fact that the solar system has sat around for 4 billion years without being eaten by Von Neumann machines makes me pretty certain that we're alone. That's quite a leap you're making. One very strong counterargument boils down to simple economics: where's the profit motive in building a fleet of von Neumann probes to 'eat' every solar system in the galaxy? Who is going to pay for this effort, and what returns do they expect? If it takes a million years to colonize a galaxy, then unless you plan to live for two million years you aren't going to see the full fruits of your effort. As a race our attention span seems to be narrowing. As far as I can tell, despite or perhaps because of recent advances in applied science, we're actually losing our propensity to engage in multidecade R&D projects. The next LHC-scale project is going to be an almost impossible thing to sell to the governments that will have to agree to finance it, and it would take years for us to return to the Moon if our survival depended on it. We are most definitely not moving in a direction that will lead to the sort of expansionism you're talking about. Edit: here's another thing, with regard to the absence of 'radio bubbles' from other civilizations. It's really, really dumb, from a technical perspective, to transmit RF signals that are distinguishable from background noise. It means you're wasting power and throwing away channel capacity. Look at an HDTV transmitter on a classical spectrum analyzer sometime, and you won't see much in the way of coherent structure -- you'll just see a pedestal where the noise floor seems a bit higher than usual. This means that the 'radio bubble' is not a bubble, but two nested spheres with only about 100 light years of space between them. To observe emissions from an advanced civilization, we need to look at just the right time, between the development of RF technology and information theory. Otherwise we won't hear a thing.
- AngryParsley 16y ago
  I guess the inferential distance between us is too great. A world in which we colonize the stars is a world where we've fixed some of the problems today (aging, death, existential risks from various technologies). I assume humanity will change substrates to something that lasts a little longer than our current bodies. where's the profit motive in building a fleet of von Neumann probes to 'eat' every solar system in the galaxy? Who is going to pay for this effort, and what returns do they expect? You only have to build one Von Neumann probe, and there's a massive benefit to taking over your light cone: You make sure nobody else does. Even if million-year life spans are out of our reach, why does one have to live to see the full fruits of one's effort? The world doesn't cease to exist when you die.

robryan 16y ago

What if most civilisations either destroy themselves or are wiped out by a comet or changing star conditions or an irregular orbit, or any number of things. If life truly does take as much time to become intelligent enough to actually tackle space travel there is a lot that can go wrong in the 4 billion year interim. Plus that requirement rules out a great number of stars which don't live long enough. Even our civilisation, any number of things could still go wrong before we are able to explore the universe. I wouldn't be surprised if we find a decent amount of life of the single cell variety. There is also the possibility of a civilisation far older than ours that never really got going on the intelligence path, or are lacking a good supply or certain base materials to really get going.

eru 16y ago

Please read `Burning the Cosmic Commons: Evolutionary Strategies for Interstellar Colonization' (http://hanson.gmu.edu/filluniv.pdf http://hanson.gmu.edu/filluniv.pdf) from the wonderful collection `The Economics of Science Fiction' (http://hanson.gmu.edu/econofsf.html http://hanson.gmu.edu/econofsf.html). The paper provides an explanation for us not having seen those probes that still allows other civilizations to exist. From the abstract: "Attempts to model interstellar colonization may seem hopelessly compromised by uncertainties regarding the technologies and preferences of advanced civilizations. If light speed limits travel speeds, however, then a selection effect may eventually determine frontier behavior. Making weak assumptions about colonization technology, we use this selection effect to predict colonists' behavior, including which oases they colonize, how long they stay there, how many seeds they then launch, how fast and far those seeds fly, and how behavior changes with increasing congestion. This colonization model explains several astrophysical puzzles, predicting lone oases like ours, amid large quiet regions with vast unused resources."

CamperBob 16y ago

The fact that the solar system has sat around for 4 billion years without being eaten by Von Neumann machines makes me pretty certain that we're alone. That's quite a leap you're making. One very strong counterargument boils down to simple economics: where's the profit motive in building a fleet of von Neumann probes to 'eat' every solar system in the galaxy? Who is going to pay for this effort, and what returns do they expect? If it takes a million years to colonize a galaxy, then unless you plan to live for two million years you aren't going to see the full fruits of your effort. As a race our attention span seems to be narrowing. As far as I can tell, despite or perhaps because of recent advances in applied science, we're actually losing our propensity to engage in multidecade R&D projects. The next LHC-scale project is going to be an almost impossible thing to sell to the governments that will have to agree to finance it, and it would take years for us to return to the Moon if our survival depended on it. We are most definitely not moving in a direction that will lead to the sort of expansionism you're talking about. Edit: here's another thing, with regard to the absence of 'radio bubbles' from other civilizations. It's really, really dumb, from a technical perspective, to transmit RF signals that are distinguishable from background noise. It means you're wasting power and throwing away channel capacity. Look at an HDTV transmitter on a classical spectrum analyzer sometime, and you won't see much in the way of coherent structure -- you'll just see a pedestal where the noise floor seems a bit higher than usual. This means that the 'radio bubble' is not a bubble, but two nested spheres with only about 100 light years of space between them. To observe emissions from an advanced civilization, we need to look at just the right time, between the development of RF technology and information theory. Otherwise we won't hear a thing.

AngryParsley 16y ago
I guess the inferential distance between us is too great. A world in which we colonize the stars is a world where we've fixed some of the problems today (aging, death, existential risks from various technologies). I assume humanity will change substrates to something that lasts a little longer than our current bodies. where's the profit motive in building a fleet of von Neumann probes to 'eat' every solar system in the galaxy? Who is going to pay for this effort, and what returns do they expect? You only have to build one Von Neumann probe, and there's a massive benefit to taking over your light cone: You make sure nobody else does. Even if million-year life spans are out of our reach, why does one have to live to see the full fruits of one's effort? The world doesn't cease to exist when you die.