As these characters have been searching for Earth and encountering countless barren uninhabited worlds, finding some form of life, intelligent or otherwise,
To summarize the portion of that article of interest: A silicon atom is.3 nm across. We are currently building transistor devices on 45nm processes. So if we reduce the process size to a single atom (and that's being generous: how do we control a device composed of one atom?), we'd achieve 150x density, in two directions, which would be 22,500 times improvement. That's enough for less than 15 more doublings, but I'll be generouse and give you the full 15. So if Moore's law is 18 months (and heck, I'll give you 24 months for doubling these days as things slow down, and remember when it was 12 months?) then we have 30 years left in Moore's law, before we hit 'devices' that are somehow magically made out of single atoms, yet still do the work we expect them to do.
There are a few other points to consider.
1)Chips are almost pure silicon, but they require dopants to function. When you shrink the transitor size down to a cluster of a few hundred atoms or so, expect the properties to change, since you'll have to effectively make the impurities 1000 times more concentrated to maintain at leat 1 dopant atom per device. Shrink the transistor down to a half-dozen atoms, and the dopant is now a major component of the transitor (17%) instead of a trace impurity (0.001%).
2)The hole/electron associated with a dopant atom isn't tied down to a precise location in the crystal...It tries to stay in the general vicinity of the dopant atom, but due to the laws of quantum mechanics (and thermodynamics) these charge carriers tend to wander around the crystal a bit. If you attempt to pack devices too close together, this will result in charge carriers that may not even be in the same component as the dopant atom. This means the components won't function.
We'll have to abandon silicon before shrinking transistors this small, so we'll have to swich to some other strategy for increasing component density--3D component layouts, organic transitors, etc.
We can take the differences between this guy and the time cube guy as one vector, and the differences between this guy and Archimedes Plutonium as another.
Now that we have two basis vectors, we can define a two-dimensional phase space for crackpottery instead of relying on scalars.
Now that we can apply some basic vector and tensor operations to the field of psychoceramics, think of the new discoveries to be made!
Didn't we already know how bees flew?
Didn't I watched a documentary talking about how people thought it should be impossible but thet filmed them etc and worked it out?
Certainly, a decade or two ago. Then it seems that/. posted a stroy everal years ago, and another two years after that, then another a week or two back, and now this. Isn't it obvious the increasing frequency of proofs that bees can fly is evidence we're headed towards a singularity? Will we see Ray Kurzweil predicting sentient spacefaring nanobees, and Bill Joy calling for relinquishment of honey?
While this has been proven once every two years since 1989, Slashdot readers should note this is the first time in 5 years that Slashdot has failed to review the research, the theory that honeybees can actually fly is obviously falling out of favor.
That may be the case right now, but you get a lot more energy from a glass of water than you would get from the same mass of plutonium. Right now the fusion reactors are huge, but that's hot fusion we're talking about. In order for nuclear propulsion to reach the efficiency of solar sails, you would need cold fusion.
You mean you can theoretically get more energy from a glass of water. Right now we can't break even, let alone produce enough power to operate a probe for extended periods of time. If we're going to build a probe, it has to be made with technologies that exist at the time. If we're going to build a probe in the near future, we don't even have hot fusion working, let alone cold fusion.
Nuclear reactors tend to become irradiated, the substances break down, lots of nuclear waste, that will be the biggest problem. Shielding the reactor from humans may be easy with a long structure in between the housing and the reactor, but shielding the reactor from itself is the main problem, especially if you intend it to last an interstellar voyage.
I seriously doubt we'll commit a manned mission to going anywhere we haven't explored with robots first. I'm obviously talking about the early robotic missions, and limiting technology to what's available in the next decade or so. Why would a reactor need shielding from itself? I've never heard of radiation-induced structural failure, and a carefully designed cooling system could easily isolate sensitive solid-state electronics from the radioactive material.
It hardly costs anything to beam light to a spacecraft from earth. You could run 50 gigawatts of lasers for years and you still save a lot more money than if you were to load up a nuclear powered spacecraft. You put a couple of them in the hubble orbit, highly eliptical, or better yet put them in the lagrange points. You put massive solar panels in the lagrange points to collect the light, and beam it toward the spacecraft. Better yet, just mirrors and lenses.
Sorry, I think the laws of optics would limit your range much more than you seem to believe. I'm guessing that at the heliopause, your 50 gigawatts of power would not be dispersed over the area of the solar sail, but an area of a few billion square kilometers. Even given a solar sail 100 km^2 in area, your spacecraft would only be getting about 2 kilowatts of power. Within a certain distance of the sun, solar sails are feasible, but their effectiveness drops off with the inverse square of distance while the reactor output is unaffected. Sooner or later, the reactor becomes more effective.
Even if the ion thrusters were 100 times more efficient I don't think they would be able to beat the 100% propulsion efficiency of the solar sail.
A solar sail can't make course corrections in interstellar space, either. At 600,000 mph chemical thrusters would have to be insanely massive to make a difference, so nuclear is the only option.
I wasn't referring to the nuclear isotope generators. I was referring to advanced nuclear fusion power with the highest energy densities man can come up with, still future talk at this point. Solar sails are not. I think if you want to get somewhere outside of our solar system, anything nuclear is bound to be too heavy for any hopes of a short duration trip. The best it could possibly do is less than 50% the speed of light, probably more like 25% for all practical purposes. Those nuclear power cells put out like 100 watts each or something, very little, they stack 3 or 4 or them on most missions and barely get by. A space based nuclear reactor would probably weigh 100-500 tons.
IIRC, you get a larger change in energy per nucleon (and therefore energy/fuel mass) from fission reactions than fusion. Fission tends to be a dirty process, but we're talking about not activating the reactor until you're outside the solar system.
Also, I think you're seriously overestimating the mass needed for shielding and coolant. Putting some distance between the reactor and radiation-sensitive instrument reduces the need for shielding, and we're talking about 2-5K temperatures outside the spacecraft, not 300K. Conversion of heat to mechanical energy (or directly to electricity) would be much more efficient.
And you still talk about beaming energy to the craft as a viable power source...You would need constant line of sight to deliver power--meaning you would still have to ship your power source off-planet. Even then, the beam would lose focus before you got very far away, plus tracking issues at large distances would be insurmountable--as the distance increases, errors in alignment become more crucial. For a beam tracking a spacecraft at the heliopause, error of only 1 arcsecond means you've missed the target by something on the order of 100 000 kilometers. If you allow the beam to disperse over some narrow angle to compensate (and this will happen to some extent anyway), you eventually run into the same issues as solar power. I just don't think beamed power is feasible.
In making composite materials, you need good adhesion. I know people who have done research on artificial joints, and one of the major problems with coating some substrates is that the coating peels or chips off too easily.
You also need to match coefficients of thermal expansion. It's no good having an ultra-strong composite material if it delaminates (or even bends out of shape) when you increase the temperature a few dozen degrees.
This will be highy resistant to pressure and projectiles coming from one side (the side with high compressive strength). Applying force in the opposite direction will compress the polymer layer and put tension on the ceramic layer, and much less force will be required for breaking the window (or at least popping it out of place).
The simple fix is to beam more energy at the craft.
Beamed over what distances? No beam is perfectly collimated, eventually you will get beyond the effective distance for using the beam. I'd have to dig out one of my old physics textbooks to be sure, but maybe some optics geek can tell us the limitations on this. What are some reasonable assumptions? 100 km^2 surface area for the sail? 1000 kg mass for the probe?
I'm not a rocket scientist either, but I tend to think of GIANT spacecraft when you are trying to get going really fast using propellant, the solar sails would either have to be GIANT as well in order for it to be worth the effort.
A giant spacecraft is unnecessary. A solar sail of any size won't be able to get 1 kg payload off the ground though...for that you need a chemical booster or an elevator to lift the spacecraft out of earth's gravitational well. Look at the Apollo missions--those massive rockets didn't carry the crew the entire trip, they simply boosted the command module and lunar lander into a high orbit. Have you ever seen a Saturn V rocket? Massive. Have you ever seen the space the crew had? Tiny. They had multiple booster stages, and yet those still didn't push a bus-sized spacecraft out of Earth's gravitational well.
When you talk about nuclear rockets you are talking kilotons, a solar sail powered interstellar spacecraft could be 1 or 2 tons.
NASA's probes have been using nuclear power for years. Granted, they've been using it for powering electronics, not propulsion. Still, solar electric propulsion has been tested, and you'd expect a small nuclear power source could provide sufficient energy if solar power works. Besides, we're talking about an interstellar mission here--you don't want to pack one or two instruments just to decide decades or centuries later that you need more probes. We're not talking about throwing tin cans at the nearest planet, getting to even the nearest star (other than our sun) would be too prohibitively expensive not to pack as much instrumentation as possible on to one ship.
I think travelling at 1/10th the speed of light is a practical long term goal. Solar sails are still the best option IMO. If you really want to go that fast, you MUST be travelling from one star to another, travelling around in our solar system just doesn't necessitate that kind of speed, let alone acceleration:)
Sure, but remember for solar sails your thrust drops off as the inverse square of the distance from the sun.
Don't forget that the pioneer probes are losing speed faster than expected. Presumably at some distance from the sun, drag would overpower the solar sail's thrust. IANARS (I am not a rocket scientist--although I know a few) but it seems to me a three-stage system would be needed for interstellar travel:
1) chemical propulsion to leave the surface of Earth (unless an elevator can be built)
2) A solar sail, deployed between earth orbit and some place near (or slightly past) the heliopause
3) MHD/ion drive for interstellar space.
In case my previous post wasn't clear, I meant the discovery of high-temperature superconductors occurred here at UAH. Obviously UAH is in Huntsville, not Leiden.
Superconductivity was discovered by Kamerling Onnes in Leiden in 1911.
1987 was an impressive year in superconductivity research because the first material which became superconducting above liquid nitrogen's (as opposed to the much more expensive liquid helium) boiling point was discovered. Of course, this discovery was not made in some IBM research lab, but here at The University of Alabama in Huntsville.
You have to admit the gorilla using a stick to determine the depth of water was impressive.
Plenty of animals use tools, but how many use tools to make measurements?
Further, he added, "this proposal acknowledges that Open Document does not address pictures, audio, video, charts, maps, voice, voice-over-IP, and other kinds of data our customers are increasingly putting in documents and archiving."
Voice-over-IP in documents and archiving? Does that make any sense at all?
Of course, maybe he means recorded conversations since he also seems to classify "audio" and "voice" separately, but if you have to call the same content by three different names to make it sound like you're offering more features, then he's really not offering as many extra features as he wants customers to believe.
One of the darkest moments of working for a major retail chain betweeen college and grad school was the realization that I had to sell the likes of packard bell computers. The single bright spot was the time I put packard bell tech support on hold.
It seems to me you're confusing "impure" with "imperfection."
All solid-state matter will contain some defects, but "purity" refers to composition, not structure.
quickly falls off when the shuttle reaches high velocity (air pressure)
..then you have the shuttle running into high-velocity debris in mid flight instead of low-velocity debris at the launch pad. Remember the Columbia was travelling at 0.4 Mach when it was struck by debris...nowhere near top speed, but not too slow, either.
evaporates when it reenters the atmosphere?
Reentry isn't the issue, since the fuel tank is jettisoned much earlier. Also, you'd much rather run into debris at 1/5 the speed of sound than 5-10x the speed of sound. The main problem is cryogenic fuel producing a strong temperature gradient across the foam insulation...while the shuttle is sitting on the launch pad, air actually condenses inside the foam cells on the cold side, and later warms up and boils off, producing a "popcorn" effect which blows small chunks of the insulation off.
Nuclear power really won't take you very far unless you use breeder reactors. About 40 years by some estimates.
I've heard that if the existing weapons-grade plutonium were converted to reactor fuel (by "diluting" it with other isotopes) we would have enough to last 250 years.
BTW, don't you mean breeder reactors produce Pu-239 instead of Pu-238? I've never heard of Pu-238 being used for fission before.
Actually more than that. Silicon, germanium, and diamond all share the same crystal structure as well as the same number of valence electrons per atom. While at room temperature we normally think of diamond as an insulator, at high temperatures it can serve as a high-bandgap semiconductor.
It's not the sort of thing you want to build your CPU from, but diamond and silicon carbide are good choices for devices intended to function at high temperatures.
Slashdot Mirror
1)Chips are almost pure silicon, but they require dopants to function. When you shrink the transitor size down to a cluster of a few hundred atoms or so, expect the properties to change, since you'll have to effectively make the impurities 1000 times more concentrated to maintain at leat 1 dopant atom per device. Shrink the transistor down to a half-dozen atoms, and the dopant is now a major component of the transitor (17%) instead of a trace impurity (0.001%).
2)The hole/electron associated with a dopant atom isn't tied down to a precise location in the crystal...It tries to stay in the general vicinity of the dopant atom, but due to the laws of quantum mechanics (and thermodynamics) these charge carriers tend to wander around the crystal a bit. If you attempt to pack devices too close together, this will result in charge carriers that may not even be in the same component as the dopant atom. This means the components won't function.
We'll have to abandon silicon before shrinking transistors this small, so we'll have to swich to some other strategy for increasing component density--3D component layouts, organic transitors, etc.
We can take the differences between this guy and the time cube guy as one vector, and the differences between this guy and Archimedes Plutonium as another.
Now that we have two basis vectors, we can define a two-dimensional phase space for crackpottery instead of relying on scalars.
Now that we can apply some basic vector and tensor operations to the field of psychoceramics, think of the new discoveries to be made!
Certainly, a decade or two ago. Then it seems that
Isn't it obvious the increasing frequency of proofs that bees can fly is evidence we're headed towards a singularity? Will we see Ray Kurzweil predicting sentient spacefaring nanobees, and Bill Joy calling for relinquishment of honey?
While this has been proven once every two years since 1989, Slashdot readers should note this is the first time in 5 years that Slashdot has failed to review the research, the theory that honeybees can actually fly is obviously falling out of favor.
Alcohol + acid -> Ester + water
Carrying this out in water would shif the equilibrium to the left.
It's probably better to use ethanol as both reactant and solvent.
Why would a reactor need shielding from itself? I've never heard of radiation-induced structural failure, and a carefully designed cooling system could easily isolate sensitive solid-state electronics from the radioactive material.Sorry, I think the laws of optics would limit your range much more than you seem to believe. I'm guessing that at the heliopause, your 50 gigawatts of power would not be dispersed over the area of the solar sail, but an area of a few billion square kilometers. Even given a solar sail 100 km^2 in area, your spacecraft would only be getting about 2 kilowatts of power. Within a certain distance of the sun, solar sails are feasible, but their effectiveness drops off with the inverse square of distance while the reactor output is unaffected. Sooner or later, the reactor becomes more effective.A solar sail can't make course corrections in interstellar space, either. At 600,000 mph chemical thrusters would have to be insanely massive to make a difference, so nuclear is the only option.
Also, I think you're seriously overestimating the mass needed for shielding and coolant. Putting some distance between the reactor and radiation-sensitive instrument reduces the need for shielding, and we're talking about 2-5K temperatures outside the spacecraft, not 300K. Conversion of heat to mechanical energy (or directly to electricity) would be much more efficient.
And you still talk about beaming energy to the craft as a viable power source...You would need constant line of sight to deliver power--meaning you would still have to ship your power source off-planet. Even then, the beam would lose focus before you got very far away, plus tracking issues at large distances would be insurmountable--as the distance increases, errors in alignment become more crucial. For a beam tracking a spacecraft at the heliopause, error of only 1 arcsecond means you've missed the target by something on the order of 100 000 kilometers. If you allow the beam to disperse over some narrow angle to compensate (and this will happen to some extent anyway), you eventually run into the same issues as solar power. I just don't think beamed power is feasible.
Not always.
In making composite materials, you need good adhesion. I know people who have done research on artificial joints, and one of the major problems with coating some substrates is that the coating peels or chips off too easily.
You also need to match coefficients of thermal expansion. It's no good having an ultra-strong composite material if it delaminates (or even bends out of shape) when you increase the temperature a few dozen degrees.
Ceramic (high compressive strength)
glass
polymer (high tensile strength)
This will be highy resistant to pressure and projectiles coming from one side (the side with high compressive strength). Applying force in the opposite direction will compress the polymer layer and put tension on the ceramic layer, and much less force will be required for breaking the window (or at least popping it out of place).
I'm not talking about hypothetical dark matter, which is no longer theoretically necessary to explain observations from what I've heard.
I'm referring to the observed slowdown of the Pioneer spacecraft.
Beamed over what distances? No beam is perfectly collimated, eventually you will get beyond the effective distance for using the beam. I'd have to dig out one of my old physics textbooks to be sure, but maybe some optics geek can tell us the limitations on this.
What are some reasonable assumptions? 100 km^2 surface area for the sail? 1000 kg mass for the probe?
A giant spacecraft is unnecessary. A solar sail of any size won't be able to get 1 kg payload off the ground though...for that you need a chemical booster or an elevator to lift the spacecraft out of earth's gravitational well.
Look at the Apollo missions--those massive rockets didn't carry the crew the entire trip, they simply boosted the command module and lunar lander into a high orbit. Have you ever seen a Saturn V rocket? Massive. Have you ever seen the space the crew had? Tiny. They had multiple booster stages, and yet those still didn't push a bus-sized spacecraft out of Earth's gravitational well.
NASA's probes have been using nuclear power for years.
Granted, they've been using it for powering electronics, not propulsion. Still, solar electric propulsion has been tested, and you'd expect a small nuclear power source could provide sufficient energy if solar power works.
Besides, we're talking about an interstellar mission here--you don't want to pack one or two instruments just to decide decades or centuries later that you need more probes. We're not talking about throwing tin cans at the nearest planet, getting to even the nearest star (other than our sun) would be too prohibitively expensive not to pack as much instrumentation as possible on to one ship.
Sure, but remember for solar sails your thrust drops off as the inverse square of the distance from the sun.
Don't forget that the pioneer probes are losing speed faster than expected. Presumably at some distance from the sun, drag would overpower the solar sail's thrust.
IANARS (I am not a rocket scientist--although I know a few) but it seems to me a three-stage system would be needed for interstellar travel:
1) chemical propulsion to leave the surface of Earth (unless an elevator can be built)
2) A solar sail, deployed between earth orbit and some place near (or slightly past) the heliopause
3) MHD/ion drive for interstellar space.
In case my previous post wasn't clear, I meant the discovery of high-temperature superconductors occurred here at UAH. Obviously UAH is in Huntsville, not Leiden.
Superconductivity was discovered by Kamerling Onnes in Leiden in 1911. 1987 was an impressive year in superconductivity research because the first material which became superconducting above liquid nitrogen's (as opposed to the much more expensive liquid helium) boiling point was discovered. Of course, this discovery was not made in some IBM research lab, but here at The University of Alabama in Huntsville.
You have to admit the gorilla using a stick to determine the depth of water was impressive. Plenty of animals use tools, but how many use tools to make measurements?
Voice-over-IP in documents and archiving? Does that make any sense at all?
Of course, maybe he means recorded conversations since he also seems to classify "audio" and "voice" separately, but if you have to call the same content by three different names to make it sound like you're offering more features, then he's really not offering as many extra features as he wants customers to believe.
One of the darkest moments of working for a major retail chain betweeen college and grad school was the realization that I had to sell the likes of packard bell computers. The single bright spot was the time I put packard bell tech support on hold.
It seems to me you're confusing "impure" with "imperfection."
All solid-state matter will contain some defects, but "purity" refers to composition, not structure.
..then you have the shuttle running into high-velocity debris in mid flight instead of low-velocity debris at the launch pad. Remember the Columbia was travelling at 0.4 Mach when it was struck by debris...nowhere near top speed, but not too slow, either.
Reentry isn't the issue, since the fuel tank is jettisoned much earlier. Also, you'd much rather run into debris at 1/5 the speed of sound than 5-10x the speed of sound.
The main problem is cryogenic fuel producing a strong temperature gradient across the foam insulation...while the shuttle is sitting on the launch pad, air actually condenses inside the foam cells on the cold side, and later warms up and boils off, producing a "popcorn" effect which blows small chunks of the insulation off.
I've heard that if the existing weapons-grade plutonium were converted to reactor fuel (by "diluting" it with other isotopes) we would have enough to last 250 years.
BTW, don't you mean breeder reactors produce Pu-239 instead of Pu-238? I've never heard of Pu-238 being used for fission before.
Actually more than that. Silicon, germanium, and diamond all share the same crystal structure as well as the same number of valence electrons per atom. While at room temperature we normally think of diamond as an insulator, at high temperatures it can serve as a high-bandgap semiconductor. It's not the sort of thing you want to build your CPU from, but diamond and silicon carbide are good choices for devices intended to function at high temperatures.
Isn't calcium hypochlorite used to kill microorganisms in US drinking water?
After reviewing SCO's various amended complaints, it seems you are correct.