Not so sci-fi. USA life expectancy has been dropping since about 2014.
That's a really good idea.
Even before apps, if elevators simply had the destination-floor buttons in the hallway outside the elevator, they could have gained some of the same 'carpooling' efficiency you describe.
Also, in a really big arcology, the distinction between elevators and subways would be moot. You would just pick a room number, and a single vehicle would zigzag its way through vertical and horizontal tubes to your closest stop, anywhere in 3D.
High quality VR could remove some of the pressure on transit, but unmanned freight would still be going all over the place this way.
Isaac mentioned the Elevator Conundrum for tall buildings. Part of the issue today is that every shaft can only carry one elevator.
You could alleviate this with a system of 2 shafts, an 'Up' shaft for multiple ascending elevators, and a 'Down' shaft for all descending ones, going in a loop forever. It would work like a vertical commuter rail.
Then as any shaft got taller, the number of elevators and people it could carry would scale up with it.
BTW it would be yet more efficient if it worked like Personal Rapid Transit.
In this approach, each elevator would move a little sideways out of the main shaft to load and unload people. Then other elevators could pass it non-stop, making every trip potentially an express trip.
I imagine you'd need some sort of vertical electromagnetic rails to run this, rather than the traditional pulleys and hydraulics.
I'd like the additional option of:
Everywhere in the solar system that can support life has life, and all of it will be related to Earth life.
I think this is likely because all of our planets have been spraying each other with debris continuously for billions of years, from meteor impacts, etc. A sterile environment would be almost impossible.
I think that's a bit fast for that diameter. All the math you need is here: en.wikipedia.org/wiki/Centripetal_force
No you would not float away. Remember even if you jump up, you are still moving at about the same speed as the ground under your feet, so you will 'fall' back down.
To a stationary (non-spinning) outside observer, it would look as if you were flying at a tangent inside the cylinder, which would take you on a collision course back to the inside of the curved cylinder wall.
On the other hand, if you could run against the direction of the spin as fast as the cylinder is spinning, then you would end up in free fall and then you really would start floating. For a cylinder that big you'd have to run
2 * pi * 4km * 2rpm = 50.2654824574 kilometers per minute I think. You might need a jet plane.
Even so, if there is any air inside the cylinder then air drag would pull you back up to cylinder speed again and you would go back to 'falling'.
I think that private corporations are usually even more risk-averse than governments, because they are more nervous about their bottom line. So I also don't see privatization in itself as a magic bullet.
But the big picture is that technology is changing. Even if launch costs remain frozen and institutions remain timid, miniaturization and AI are going to make Moon and asteroid mining increasingly cheap and easy, until potential profits exceed the needed investments.
So who wants Moon metals? Our existing satellite industry. As long as launch costs are high, building satellites in Earth orbit from in situ materials will make economic sense, once remote control is capable. Northrop Grumman has already developed Mission Extension Vehicles, basically robot sats that fly around repairing other satellites, and there is no reason this won't evolve from repair to fabrication as things get more advanced.
This creates an economic spiral. More working robots in space means more mining and materials in space, lowering the per-kg cost of objects in space, and more materials means more robots and raw hardware.
Finally: what good does this do humans? When the launch costs of building a space habitat or ship approach zero, launching a human drops to just the cost of sending his/her flesh. All food, oxygen and shelter are already up there, waiting to be inhabited.
Also, if the satellite industry creates wealth multipliers on the ground (solar power? rare elements? exotic jewelry?), even more humans will be able to afford to go on top of that.
Yes it is quite addictive. I think it is because its weirdness, and the promise of really cheap hobby access to space. I am a big fan of paradoxes.
I'm using Zeppelin shapes because it's so easy to get data on them. If we had good data and math on JP's V-shaped craft it'd be cool to do that too, but as you say there isn't much information yet. Fish are good at fluid dynamics though, so a fish-shaped craft is still valid.
And we can still do art!
Yes I was thinking along the same lines. EHD thrusters count as electronic 'jets' in that they react against ambient air. But maybe we could take it one step further with oscillating charges on the surface of the airship:
Positive charges are red, negative are blue, and the thin black lines are lightweight high-voltage low-current wires doing the 'wave'. This assumes the atmosphere is already ionized.
1. It uses its whole gas envelope surface for traction against the air. (Could this even reduce drag?)
2. Nothing interrupts the streamlining of the hull shape.
3. You can dial in any speed you like by tuning the ring frequency.
4. The drive does not have to decelerate oncoming air to push against it.
1. It needs electricity! Lightweight power sources might be out of reach for today's technology.
Even without hitting orbit, I would love to see a whole menagerie of giant filmy airships oozing around in the ionosphere. Their aerodynamics would be neither for space or for sea level, but more like the environment inside of a novelty plasma globe.
That said, maybe you could reach orbit on a jet if you built up enough inertia before leaving the atmosphere, kind of like a whale breaching out of the sea. Or, maybe after jets get you to the very edge, ion rockets power up as the second stage for the rest of the trip.
If I was JP Aerospace, I would make propulsion research a top priority. The only difference between airship-to-orbit and a weather balloon is ATO can go sideways. I would invest in a low-pressure wind tunnel and test the heck out of every EHD configuration I could think of. They're probably smart to start with chemical rockets though, that will get a lot of data.
Playing with parameters some more...
If you increase the USLA's thrust by about 20% to 7728 newtons, and you somehow achieve neutral buoyancy at 80 kilometers altitude, then your airship's terminal velocity will be orbital speed and your balloon can leave the planet.
Atmospheric density at 80km is 0.00001846 of what it is at sea level though. This means that our airship needs to have 54,171 times the volume of the USLA while retaining the same drag and mass. (Taking the cube root, that is equivalent to making the USLA 38 times bigger in height, width and depth.)
Or if you like, keep the USLA the same size but make it 0.00001846 of its original mass. I don't have the dry weight of the USLA, but within the same order of magnitude, the Hindenburg weighed 215,002.78 kg (474,000 lbs en.wikipedia.org/wiki/Hindenburg-class_airship).
So 215,002.78 kg * 0.00001846 = 3.9 kg maximum mass.
So yes, airship to orbit is possible if your ship is as big as a zeppelin with a little more thrust, and a total mass of about 4 kilograms (8.5 lbs). That weight must include gas, rockets, payload and everything. We may be talking about a vacuum dirigible (as in The Diamond Age?)
You might benefit by replacing your ion rocket with some kind of ion jet, using ambient air as reaction mass. That way you won't need to worry about low specific impulse or carrying a lot of heavy fuel. Conveniently, 80km is right in the ionosphere so your air is already charged and ready to be pushed.
Airship to orbit is a weird and fun problem to work out.
At first you think 'Ridiculous! Airships are big and floppy and full of drag. No way could you reach orbital speed without exploding.'
But then you think 'Wait, there's no drag in a vacuum, and at high altitude air density is nearly vacuum.' How fast can a balloon really go up there?
To find out, let's start with some real-life airship parameters...
The highest an airship has ever gone is about 50 kilometers above sea level. Then we will use the US Los Angeles (USLA), a real airship with known max speed, but make it light enough to be neutrally buoyant at 50 km altitude, and see how fast it can go in that air density.
Stats on the US Los Angeles to plug in:
radius = 13.8 meters (en.wikipedia.org/wiki/USS_Los_Angeles_(ZR-3))
resistance_area = Math.PI * radius * radius = 598 square meters (circular profile)
top_speed = 89 kph (24.72 meters per second)
drag_coefficient = 0.023 (ntrs.nasa.gov/citations/19930091470)
Our math will be mostly the terminal velocity equation: (en.wikipedia.org/wiki/Terminal_velocity#Physics). This is the same terminal velocity skydivers use. It only refers to the point at which air friction cancels out your thrust and your speed plateaus.
Before we start, we have to calculate the thrust of the USLA, given that its top speed was 89 kph (24.72 meters per second) at about sea level. Using the terminal V equation backward, solved for thrust, plug in 24.72 for terminal_v under full power:
thrust = (terminal_v * terminal_v * (resistance_area * drag_coefficient)) / 2.0;
So the USLA's thrust would have been about 5363 newtons.
Now that we know thrust, how fast can the USLA go at 50,000 meters altitude on 5363 newtons thrust?
Air density at that altitude is = 0.001027 kg per cubic meter. (www.engineeringtoolbox.com/standard-atmosphere-d_604.html)
So we plug all our values into the terminal V equation the normal way to get max speed:
terminal_v = sqrt((2.0 * thrust) / (air_density * resistance_area * drag_coefficient));
and you get 871 meters per second (1,948 miles per hour = mach 2.5)!
LEO speed is 7800 meters per second, so that's over 11% of orbital speed!
Not bad for a big floppy air bag.
Of course the US Los Angeles propellers won't work at that altitude, so we'd assume this thrust is delivered by rockets.
While these parameters can't reach orbital speed, you could maybe run a 'first stage' service to deliver rockets to 11% orbital speed in near-vacuum before they launch. I think this would save the rocket more than 11% of its fuel because a rocket's worst mileage is at the start of its trip, when it is carrying the most fuel.
All the math is in Java code in case anyone wants to plug in their own parameters.
Thanks for the links. Your diagram of an ion beam printer makes sense. If you are doing some physical experimentation, have you tried anything with vacuum yet?
This was the first I saw Isaac's Santa Claus Machine episode, it covered even more crazy constraints or paradoxes of self-rep that I hadn't considered before.
In one part he mentioned a debate where the participants agreed that an array of printer heads/nozzles cannot print something as large as itself without moving, thus imposing a mechanical speed limit. Fortunately this is not true. Imagine the checkerboard surfaces are arrays of printer heads:
The child machine can be as big or bigger than the parent, if the parent's longer axes are each greater than the parent's shorter axes, and it prints the child perpendicularly to itself.
In fact, this way each generation can be larger than the previous, so you could start with a print surface the size of a poker card and gradually bootstrap to a generation of children as big as mattresses. Self-rep clown car!
Also, if the printer heads are projecting beams of material that can be swept back and forth like the scan of a cathode ray tube, they can cover even more space without mechanical movement of the parent.
Your diagrams are clear. I wish I understood this topic better. From the Machine Thread I've been reading more about particle accelerators lately.
I think one edge cyclotrons have over linear acceleration is that they can apply force on the same propellant many times with the same hardware. Imagine if you are a rocket and your propellant is a bowling ball. First you push the ball out the stern and get some thrust, but a second later you can reach out with a long pole and push against the ball again and get some more thrust, and a second later again, and so on, until nearly all of your momentum comes from the ball's speed and not its mass. To match this a linear accelerator would have to be extremely long, with many redundant rings.
So we're sort of talking about an iterative ion drive 'recycling rocket'? It could be a whole species of propulsion with a lot of different approaches.
Again I can't answer your questions, but if you are looking for flaws, maybe one of them would be that something of any significant mass spinning at 20% of C could tear your engine apart. Don't know if that is a deal breaker though. The mass is held together by a magnetic field. So if the propellant is on both sides of the loop it may pull against itself as much as against the magnet.
So perhaps the next math problem is to figure out the centripetal 'force' a regular ion drive would have to endure, if the ions were moving in a circle at relativistic speeds?
Having some fun with Blender: "Clanking Replicator Digestive Tract". Click to embiggen.
1. Molten child material never touches the parent, so the parent can make children out of materials more robust than its own.
2. No moving parts, so can be printed as a single block.
3. Ion beam deposition is very precise, enough to print circuits and capacitors.
4. While regolith dust can be sifted and poured into the top, even with no one feeding it, floating charged dust particles on the Moon will gradually settle on to the top plate and be consumed. It is always eating and building as long as it has power.
5. Every part of this is something that has been done before.
1. This assumes a significant amount of regolith is electrically conductive. There is some evidence for this but we need more samples. If it is not conductive, use electrostatic levitation instead?
2. Ion beam deposition is slow, because it is so fine. Maybe a less precise, higher-volume version is possible?
3. Probably an energy hog. Simplicity is prioritized over efficiency. Probably 99% of this thing's life would be spent printing solar cells.
4. It doesn't poop. Any realistic refinery is going to have waste products, so you'd need an extra ion chute to project the waste away from child production.
5. None of these processes have been tested together.
That is the perfect movie scene for this post.
Rereading this, the split-brain outcomes are not as exactly as I had thought they were. The hemispheres are definitely not identical, but do both act like independent people, one who can speak and one who cannot.
You know, this could lead to a sci fi/horror story of someone who achieves immortality by splitting their brain and putting each half into 2 unfortunate victims every generation.
Every time the mad doctor installs his/her half-brain in a victim, they also install a 'blank' hemisphere (3d printed? cloned baby brain?), which will absorb all of the thoughts and experiences of the older mad-doctor hemisphere, becoming a complete, imperfect 2-hemisphere copy of the doctor's personality.
Eventually you would have hundreds of slightly-different copies of the same doctor running around, possibly getting into fights with each other. The protagonists have to hunt them all down and stop them.
Since it is uploading without computers, maybe it could be set around the 1950s, or even 1800s, Frankenstein's century.
You don't even need science fiction for the teleportation question.
In a patient who has had the two hemispheres of their brain cut apart from each other, when they are tested, it seems each side of the person's brain believes itself to be the original, complete person. This in spite of the fact that each hemisphere doesn't seem to know what the other is thinking or even doing.
In these people an entire half of the forebrain has been amputated, usually for untreatable epilepsy. But after surgery, family members say that the patient's personality and sense of humor remain entirely intact, with maybe some paralysis on one side.
This paints the picture that our hemispheres are basically 2 copies of one personality. Not exact copies, but close enough to fool our loved ones and even ourselves. Neither one is the 'real' or 'fake' person.
The uploading of one side to another probably happens continuously throughout our lives. A computer analogy would be two servers which mirror each other by exchanging all of their most recent changes every day.
So it's kind of amusing that all the pop fiction imagines uploading ourselves to computers -probably the hardest way possible to do such a thing- when it is a lot more plausible to upload ourselves to real, living brain tissue.
My thoughts exactly. Computing machinery would be very hard to make, and often unnecessary with Earth so close. It may be that every 'muscle' has its own RF channel to the Mothership. The first generation of bots delivered from Earth might have big brains for local AI and communications, but not their children.
The fun challenge of self-rep is keeping things as low-tech as possible, because every convenience we add makes forging the next generation more difficult.
So we don't want the most efficient solar cells, we want the ones that are easiest to build, and build 10 times as many to make up for the losses.
Rather than integrated digital circuits, we might prefer vacuum tubes, mechanical relays, or 1950s semiconductors because they are easier to make from scratch.
Our building materials may be only as pure as were available in the 19th century, and we just have to live with it, etc.
You have to un-invent so many dependencies, it gets kind of Zen.
Yes, the first priority is to build up maximum robot 'biomass' on the Moon until an order is given to start making the things we need. After the population is large and stable, it can ascend a spiral of complexity to create purer materials and fancier machinery.
Here are some links I hope to reference later in a hypothetical design...
"Lunar dustbuster" pushes regolith dust across surfaces by peristaltic oscillation of static charges:
Using microwaves to convert glass to plasma:
Explanation of this thermal runaway effect:
Levitated induction melting (Just google "induction levitation melting" or "cold crucible"):
"Levitation Zone Refining and Distillation of Plutonium Metal" (Using induction levitation melting as a smelter, to purify metal)
Lunar regolith can be surprisingly conductive, especially when hot: