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Comment Re:Rockets are too expensive (Score 1) 315

Sure, one built with imaginary and probably impossible materials, ignoring petty little details such as the non-equivalence of the accelerating inertial reference frames at the ground and top (not to mention all of the way up).

Here's a hint for you (and everybody else that proposes this absurdity):

a) Equatorial speed relative to center of Earth: 460 meters/second or just over 1000 mph. Around 1.35 x the speed of sound.
b) Speed at geosync orbit at R \approx 6 R_e: 6 x 460 = 2.78 km/sec.

Or if you prefer energy:
c) Total mechanical energy of 1 kg object sitting at "rest" at equator: = GMm/R_e + 1/2 m v^2 (using v from a) above): -64 MJ/kg
d) TME of same object sitting at "rest" in geosync orbit \approx -10 MJ/kg

And the worst of them all, angular momentum:
e) Total z-directed angular momentum of 1 kg on equator = mR_e v (from a): 2.9 x 10^9 kg-m^2/sec
f) Ditto at geosync (36x larger): 105 x 10^9 kg-m^2/sec

So, to lift something up from the surface to geosync, one has to:

1) Increase its tangential speed -- tangent to great circles around the axis -- by a factor of 6 as it rises.
2) Increase its mechanical energy by 50 million Joules per kilogram of payload.
3) Increase its angular momentum by well over 100 BILLION kg-m^2/sec. This is done by means of the same torque required to increase its tangential speed.

Now, let's ignore all the picky details, such as how to make a cable that can support its own weight hanging to the ground from geosync orbit -- where if we not unreasonably insist on it having a specific gravity around 1 (same as water) then we need the weight of a cable well over 5 R_e long (at least, if you want to be able to apply tangential force via the same cable) so let's START with 5 R_e -- in round numbers 5 x 6.4 x 10^6 = 32 million meters long (yes, that is million). Figuring the top tension is a bit tricky and involves an integral, but the result of the integral is that the tension at the top is the change in potential energy per kilogram times the density times the cross sectional area: GM_e\rho \Delta A (1/R_e - 1/6R_e) = 50 MJ/kg x 1000 kg/m^3 \Delta A.

This is 50 x 10^9 Newtons times the cross sectional area (in m^2), and is most easily expressed by dividing out the area to get:

Requirement: 50 GPa minimum tensile (yield!) strength

The highest tensile yield strength observed in any material (so far) is less than 5 GPa. Carbon nanotubes have a tensile strength reported as high as 63 GPa, but this is not a yield strength and could not support a sustained load, certainly not safely. So far, then, we are (honestly) well over an order of magnitude short of the required yield tensile strength required for a cable to JUST support its own weight "hanging" from the vicinity of geosync orbit. One cannot force a lower orbit USING such a cable, and higher orbits (with more cable) that are still geosync require more tension and make little sense. But hey, this is science fiction, let's PRETEND that we can make carbon nanotube cables 32 million meters long that have a yield strength of (what the hell) 500 GPa -- our 50 plus a generous margin of safety. Let's not worry about what we are going to wrap our cable around as far as pulleys go at the ends, how we will build bearings etc -- heck, that's just "engineering". Heck, anybody can design a pulley that can support a 64+ million meter long cable (looped, remember! -- oops, there goes a factor of 2 of our ten already!) that has been looped and joined "perfectly" without the slightest defect that might lower the yield strength to (say) 5 GPa and lead to catastrophe! Engineering is just drawing a picture! Why worry about what actual material you might make it out of that the cable won't cut right through (if it is thin) or crush (if it is thick) or wear out in short order as it operates?

Let's just imagine how it might WORK. After all, the whole idea is that you send a payload up on one side of the loop at the same time you send some counterweight down on the other, adding energy as needed with the bottom pulley.

Still, we have to add all of that velocity, energy, and angular momentum to the mass WHILE IT RISES! This means that the cable has to exert: a) enough vertical force on the payload mass to overcome local gravity. This comes out of the total tension budget but hey, we assumed that we could build a cable with enough surplus to be able to lift several times the weight of the cable, however thick or thin we make it. We just make the cable thick enough that the cable plus payload are WELL within this utterly imaginative, fictitious, limit. b) enough TANGENTIAL force to be able to exert the required torque on the payload as it rises! And this is a very, very serious problem, one that it will not be easy to overcome with science fiction.

For one thing, this utterly rules out "straight" cables. Even if you JUST run the loop WITHOUT payload, the rising cable will (apparently) deflect to antispinward/west in order to build up enough of a bow for the tension in the cable to be able to provide the necessary torque on the cable itself. The bigger the bow, the better the angle, but the longer the cable (and what do you do with all of that cable when you AREN'T running the loop? Hmmmm....) the greater the static tension, operating or not. The smaller the bow, the flatter the angle, the bigger the tension needed to provide the transverse acceleration/torque as well as lift the payload.

In the meantime, the descending cable is going TOO FAST for the ground. It balloons out spinward/east as it descends. The operating loop doesn't look like two vertical lines, then. It looks like two enormous arcs, stretched in opposite directions!

Lifting the mass has two more really interesting effects. One is that the cable pulls the geosync end DOWN relative to static tension equilibrium when you load it. The loops have to come from somewhere, and if the station stretches the cables "tight" at equilibrium, the opening of the loops has to reduce the vertical span of the loop, period. Moving it down moves it out of geostationary stasis -- the station ITSELF starts to deflect to spinward as it is going too fast for a lower circle at constant angular velocity (there are lovely demonstrations of this involving coin spirals in shopping malls or figure skaters). As the mass rises, though, it pulls backwards on the station. It is basically undergoing a "slow" inelastic collision with the station! It started with the wrong angular momentum (too low, from Earth's surface). The Earth's surface cannot ADD angular momentum to the space station -- it moved forward because it was being conserved when we turned on the loop and it moved to a lower circle! But as the particle rises, it really DOES reduce the angular momentum of the space station as it increases the angular momentum of the payload. In fact, overall, it is sort of like you fired the payload at the station in the direction opposite its motion at 2 km/sec, and the mass then collides with the station and sticks!

It doesn't happen that fast and it may not release heat during the collision (assuming our motors do their work) but as far as angular momentum is concerned, that's what happens. The rising mass pulls antispinwards on BOTH the mass AND the space station, but the space station is not fixed.

At the end of the day, if the station was in geosynchronous static tension equilibrium before you sent up your payload, after you've sent an unbalanced load up it is not, basically because strings cannot exert any shear stress on the space station and can exert tangential forces on the mass only by pulling the station down to a different radius. And this is all in the quasi-static limit, ignoring the WAVES that any loaded motion would induce on the loop and just what happens to the slack that develops in the loop.

In the end, you have to add energy and angular momentum back to the station plus platform in order to re-achieve geosync orbit. To do that, you are right back to using rockets (or still more science fiction).

Let's face it. The "space elevator" concept is deeply flawed, IN ADDITION to the fact that it is currently literally impossible to build from the material science point of view. We haven't even touched on the problems building an attractive trillion dollar target in the sky that a laser or physical projectile can trivially destroy by just creating defects in the cable, in the case of a laser quite possibly from hundreds of miles away or elsewhere in orbit, or its vulnerability to space junk all along its considerable length. Stories that utilize it always seem to forget the coriolis (pseudo) "force" and the problems with inducing waves on rotating loops where one end of the loop is free floating in an either system rotating (of necessity) with a constant angular velocity. If we're going to push sci-fi, let's contemplate land-based electromagnetic mass drivers (which are in principle feasible, if still pretty absurd in cost and engineering "details").

Comment Re:Jesus saves (Score 1) 207

You mean to say Pink Unicorns COULD exist -- if we build them -- and I agree. And they could exist even if we don't. For a long time, Europeans thought that there were no black swans because they'd never seen any. They were wrong -- they just hadn't looked in the right place. Now we would say that there are no paisley dayglo multicolored swans because we've looked everywhere that one could reasonably find swans, we've catalogued swan DNA, we understand the process of evolution that gave rise to swans and the artistic human process that produces paisley and concluded that they are pretty much orthogonal, and concluded that it is very, very,.... very unlikely that there are swans whose natural feather color pattern is a riotous mix of dayglo colors arranged in perfect swirls against (say) a dark blue or violet background. But not impossible. It is likely that SOME DNA pattern, possibly intercalated from peacock DNA and then hacked a bit, could produce an animal with 99.99% Swan DNA -- morphologically a swan -- that naturally expresses paisley on its feathers. Maybe even an animal that could breed true with other swans.

As for Shetland Ponies with horns -- it's a lot easier to just drill their skulls under anesthetic and install a screw-in socket that will accept a spiral horn. Or an iron plate that one can attach a rare-earth magnetic horn to without any break in the skin. Pink dye is a lot easier than recombinant DNA. One could do that "tomorrow", if one didn't have to contend with those silly animal cruelty laws, and it isn't clear that they'd protect the pony even from this insult if the result didn't really hurt them...

Now try to do the same thing with God(s). That's why I (sarcastically) suggest that they aren't really even conceivable. Humans imagine God by:

a) Taking a purely human concept, such as that of a Human Despot (Lord, King, Emperor). They say to themselves "Hey, Lords are pretty powerful, but Kings are more powerful. And Emperors are even more powerful -- Kings of Kings as it were. I therefore can understand the sequence from me = not powerful, to my feudal lord = more powerful, to my king = still more powerful, to my emperor = most powerful in the worldly realm as an ordinal set in "power".

b) Adding other concepts -- artist/creators from me (fingerpainter) to a high school art instructor, to a modern artists who is well enough known to get shows in museums and galleries, to the Renoir's, Da Vinci's, Picasso's of the world -- an ordinal set in "creativity"; dumb as a post (e.g. farm animals), to a high school graduate, to a college graduate, to brilliant mathematicians and physicists e.g. Einstein or Ramanujan -- an ordinal set in "knowledge" or "reasoning ability".

c) Extrapolating the set. Suppose we imagine a being that is more powerful than any other being as the limit of this ordinal set. Same being is also more creative, more knowledgeable, more intelligent, more compassionate, more loving... name any positive ordinal quality, imagine a being with that quality, extrapolate to a hypothesized most whatever of that quality, possessing perfection in that quality, all with conjunctions, so that they are the most loving and most just. Don't worry too much if the two qualities are consistent, that in some sense one cannot be the most just (giving people what they deserve) and the most loving (NOT giving people what they deserve but rather what they want) -- just keep your thoughts vague enough that they don't have to confront any contradictions and imagine each "most" quality one at a time.

d) The result is God. God is bigger than the biggest, hence larger than the Universe. He is smarter than the smartest, so he knows EVERYTHING. He's more creative than the most creative, indeed anything that exists was created by God; even my fingerpaintings are really God's fingerpaintings, planned out in complete detail to the subatomic scale long before I was born. He's perfectly just (and sends sinners to hell and the virtuous to heaven) and perfectly loving (and forgives everybody their sins) and manages BOTH even though we live in a world -- that He created with perfect knowledge of how it was going to come out and hence is responsible for every detail of the actions of saints and sinners alike -- where sin is often rewarded and virtue often punished, promising to punish some people for ETERNITY with truly HORRIFIC punishments and reward others for ETERNITY with truly SUBLIME pleasures while supposedly loving them all equally and wishing that they would not do that which they were created specifically to do by the only "free" agency in such a created Universe, the Creator. A mass of self-contradictions, in other worlds, both physical (violating observational science as a matter of course), logical (being bigger than the Universe contradicts the meaning of the term "Universe"), and moral (I love you but I'm going torture you forever because you did exactly what I predestined you to do when I created the Universe).

It's a bit hard to build that little pony, with or without the horn. And for the record, human kings are a lousy metaphor for good, period, let along perfect goodness and compassion.

rgb

Comment Re: Rockets are too expensive (Score 1) 315

"You have to use small thrusters for control there"

Or steering vanes in the main rocket exhaust. No matter. This is space cadet territory. In SCLand all thing are possible if we can just get the idiots at NASA and its overseas equivalents out of the picture. Just a few minor mods to the technology and we are golden.

Right ...

There's the question of why anyone would think this is a good idea. In the history of manned space flight, there have been three 150B USD (adjusted to 2017 dollars) efforts. Apollo was pretty much a success. The Space Shuttle was pretty much a complete debacle although it is considered to be rude and impolite to mention that. And the ISS is, always has been, and probably always will be, pretty much worthless. A manned lunar colony will probably cost MORE than 150B and we'll end up with a dozen or two people living in a cave at the end of a long, expensive, supply line. There are any number of places here on Earth -- e.g. the deep sea floor -- where we could stuff a handful of people underground many orders of magnitude more cheaply and very likely more profitably.

Tell you what. Why don't we invest maybe 30B-50B USD in a fleet of lunar rovers and orbiting sensors and find out in detail what's on the moon? In a couple of decades we might know if there is any point in people going there permanently. And we probably won't kill anyone in the process.

Comment Re:Yes, but it won't happen any time soon (Score 1) 119

Streep is an exception (and good for her if she can still pull in that kind of money.) Most actors don't pull in anything like that amount of money, and even those that are able to pull in six digits or, occasionally, seven, digits per movie do so usually knowing they have a shelf life, and that Hollywood will discard them when they get into their 30s. At that point, many know they'll be difficult to hire in any other professions, as they just devoted much of their lives to a single profession, and have no skills outside of that, and have fame as an added handicap.

20 million, incidentally, is dirt cheap for a modern movie (to put it into perspective, the pilot episode of the 2000 TV series Dark Angel cost that much), and the right star can be the difference between a $60-250M movie (which is more the ballpark) either making a loss, or making an outrageous profit. The ticket price, which seems to have held steady at around $10 per adult for the last 20 years now, is what the market has determined is what people will pay, so that's not going to come down if studios were to cut actors salaries. So... why complain about this, specifically? If they're the ones making the movies profitable, and if the money's there, why not let them have a cut?

Comment Re:Just Remember, Folks. (Score 1) 169

They're announcing this shortly before the Model 3 goes into production, which will be a mid-budget vehicle.

(Also worth noting: the AutoPilot++ or whatever it's called, the version that's supposedly SAE 5 level that'll be released before the end of the year, isn't free. It's an extra people will have to pay for. If you assume SDC technology will reduce accidents by 66%, and if regular insurance is $1000 a year, then they need to price this at around $3,000 assuming a normal average ten year lifespan of each vehicle. IIRC that was the ball park for the price for the SDC add-on they're going for, so this is quite believable. You're not paying for the technology - that's already paid for, you're buying insurance for the lifetime of the vehicle.

Comment Just to add useful information (Score 5, Informative) 63

Alphabet are alleging they have specific evidence the former employee downloaded the designs to a laptop, which he then tried to wipe to hide any trace he'd done this. Alphabet are also alleging the same former employee actually bragged about what he was going to do before he did it.

So... assuming they're not lying, this is pretty much open and shut. I guess we'll find out over the next few weeks.

Comment Re:Fake News (Score 4, Interesting) 276

"No chance in hell we will use metallic hydrogen due to pressures required."

Four minutes of intensive research on this subject leads me to believe that no one is quite sure whether metallic hydrogen is stable at room temperature and one atmosphere pressure. If it is, then it'd possibly be like diamonds and many other materials. Takes enormous pressure to make (at least by squeezing it), but once made is usable. BTW, there's apparently some chance that it might not only be stable, but the fabled room-temperature superconductor.

Comment Re:so non dealer service or not paying for softwar (Score 2) 247

Sometimes the user is at fault. Maybe that means not updating software. Maybe that means after-market software or hardware modifications. Maybe that means extreme neglect of maintenance leading to mechanical failure (which happens now with non-self driving cars), assuming that self-maintaining cars will be way off in the future.

Not only can this be out of the user's control, it should be. The car should be constantly monitoring itself, and the car - being self driven - is capable of driving itself to be serviced, or calling a tow truck if it isn't capable of driving, with core functionality disabled if the car detects a state that means it can't guarantee a safe journey.

There's absolutely no reason not to take this out of the hands of the car "owner". The car doesn't have to be capable of servicing itself, it just needs to be capable of getting qualified people to provide that servicing.

Comment Re:The owner should be liable (Score 1) 247

So in other words, you believe Truth in Advertising laws should be overturned? If someone advertises a car as self driving, the consumer should be on the hook for believing them?

If a car is self driving, the manufacturer is making a claim they should stand behind. The consumer shouldn't be blamed for a fault they could not possibly predict or know about.

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