Help me break physics.

[AdamHovorka]

I realize this is really off topic, but I thought this would be a good place to get a couple outside perspectives.

I'm working on a science fiction project with an emphasis in realism (or at least self-consistency). I've been thinking about the pieces for so long now, though, that I'm not sure I've hit enough trees to make a forest (or something like that), and I fear a couple of the trees have cancer. I need some new people to look at it and tell me that I'm not crazy. Or that I am. Whichever it turns out to be.

That sounds like an introduction. So, without further ado, here's what I've got so far.

FTL Travel

My project is set in space, and where there's space you either have giant, old, slow, and boring stuff, or you have FTL. I've opted for the latter.

In fiction in general, basically all FTL drives can be classified into four categories by their usage mechanics: Warp, Jump, Gate, and Hyperspace. Warp drives bend and stretch local space to pull your destination toward you and push your source away. Nothing in our universe can travel faster than light, and that's just what this drive does; it makes nothing (space itself) travel faster than light. This is the type of drive that Star Trek is so fond of, but as I'll show later in this section, it makes ship designs look quite different from the Enterprise. Jump drives are what you see in shows like Battlestar Galactica and games like FTL. The drive teleports your ship straight from your source to your destination instantaneously. Gates (a la Stargate) work almost exactly like Jump drives, but they require pre-existing mechanisms at both ends. Finally, Hyperspace (which goes by many names: the Immaterium, Z space, Underspace, etc.) involves swapping over to another universe - and therefore another set of physical laws - moving around a bit, and popping back into our universe. I've managed to work all four forms down into two core physics ideas (twice, actually, but the first set led to time machines).

The Alcubierre Drive

I'm sure most people here have heard of NASA's warp drive project. It's based on a 1994 concept from the Mexican physicist Miguel Alcubierre. The drive design required a ring of negative energy surrounding the ship which would cause the space in front of the ship to contract and the space behind to expand while maintaining a safe, "flat" area inside for equipment and people and stuff. This negative energy is traditionally supplied by exotic matter - matter which violates certain energy conditions. The first calculations indicated that the ring would have to have a mass - a negative mass, mind you - which exceeded all of the energy in the visible universe. Fast forward to 2011, when Harold White publishes a paper on work he did which indicates that, by expanding the ring thicker than a piece of paper (which apparently nobody had thought of in the intervening 17 years) and making it so that the field oscillated on and off, the energy required in the ring could be brought down to less than the mass-energy equivalent of a Voyager probe. It still needs to be negative though, but not only could this negative energy theoretically be provided by the Casimir force, energy conditions like the ones that negative exotic matter violates were originally thought to be absolute unbreakable laws, but they've been falling one after another for years; it's really not that much of a jump to believe that the remaining few will be broken too. So basically we're down to an amount of handwavium I'm comfortable with.

The efficiency of a warp drive is based on the ratio of flat space volume to ring volume. The bigger and thicker the rings are relative to the rest of your ship, the less total energy is required. However, another couple variables are at play for the effective speed (which, by the way, doesn't necessarily have to be superluminal). I'm not going to pretend to understand all the math and relativity behind it myself, but Dr. White has said in several places that he believes that the warp effect isn't what's actually going on; he thinks it's a response from some underlying mechanic. According to the equations (an even just looking at pictures) it's apparent that the choice of "forward" for the ship is arbitrary. The warp drive works in a direction normal to the plane of the rings - it doesn't care which direction it is. What determines the direction is your velocity before the drive is turned on. This means that warp ships need some conventional form of propulsion as well so they can get up to speed.

An important point here is that while warp drives are arguably the most plausible form of FTL, in light of the other systems below they're only efficient for small ships (ships with a small livable/safe volume).

The IXS Asimov, a warp-capable ship of my own design. Yes, I did make this.

The math behind the Alcubierre Drive also allows for structures called Krasnikov Tubes. These can be compared to warp railroads; they make the individual trips easier, but they require warp equipment - analogous to rails and ties and such - to be placed along your route beforehand. Krasnikov Tubes work, for all intents and purposes, like stargates with a travel time. They would be constructed along humanity's high-traffic routes which didn't already have connecting gates or point networks (explained below).

Wormholes

Wormholes are spacetime structures which have two "mouths" which allow you to teleport straight from one to the other. If you've seen Interstellar, you know what I'm talking about. The theory of Quantum Foam indicates that, as well as particles coming into and out of existence all the time at sub-subatomic levels, wormholes likely do a similar thing. Making a wormhole transportation system is as simple as catching a pair of mouths before they annihilate and stretching them big enough to fit interesting things through. This stretching process actually requires the same exact kind of negative exotic matter as the Alcubierre drive above; the "negative gravity" pushes the mouth open.

Wormholes allowing instantaneous transportation might sound like they can be used for free energy. Stick one end above the other, drop a magnet through so it falls in an infinite loop, and situate a coil of wire along the fall path. Instant perpetual motion machine! However, this doesn't work in practice. It might sound weird, but wormhole mouths have mass. When something passes through a wormhole, the source mouth appears to gain the same amount of mass as the object, and the destination loses that mass when it comes out. If you were to try to make a perpetual motion machine, eventually the top mouth would lose so much mass that it'd evaporate and the bottom one would gain so much mass that it would turn into a black hole.

Wormhole networks can be distributed in a rather fast and interesting way. You can stabilize a pair, keep one end on Earth, and shoot the other one at a star using a mass accelerator. The traveling mouth experiences time dilation during the trip as per special relativity. If you were to have two clocks out either end of the wormhole and you looked through the mouth, they would appear to be ticking at the same rate. If you were to take a telescope and look at the clock out in space, it would appear to be ticking a heck of a lot slower. This means that while the actual trip might take decades, looking through the wormhole it could only take a month or so. Once it approaches your destination, you shoot lasers through to slow it down, suck up some mass from destination planets, and start sending stuff through only a month after you launched the mission. The thing is, when you stepped through you'd technically be years in the future. Step back to earth and you'd be right back when and where you left in the "past."

This is great until you realize that you could shoot another wormhole back at Earth. That wormhole would get there in a month for you, but decades for the Terrans. Travel through it and you're in the future at earth. Then some chuckle-head from future Earth decides to use that wormhole to travel to your planet, then use the original wormhole to go back even further in time and kill his grandpa before he can have his dad. Temporal headaches ensue, and the universe itself calls it quits and ceases to exist.

Fortunately Stephen Hawking is a genius. The universe doesn't explode because of something called the "chronology protection conjecture" which says that anything that should allow backwards time travel breaks in weird quantum ways before it can ever be used. In this case, the very moment that the round-trip time of your wormhole loop is shorter than it would take light to go the same distance, one of two things happens. Either the mouths experience a force pushing them away from each other, or (my personal favorite) infinite photons spontaneously appear along the path between the mouths and obliterate them. Crisis averted.

The time dilation effect on the mouths can be exploited for an ansible (FTL communication device) which is nice in itself because it works on all ships - warp ships and slower than light generation ships. Keep a really tiny one on your ship and shoot lasers through it for communication back to home base. The wormhole keeps the ship's time perfectly so people on both ends can talk to each other without one of them being in slow motion.

Here we hit wormhole problem number three. Allow me to illustrate: Bob is the captain of one of humanity's first interstellar slower than light ships. He's got a wormhole ansible on board, so he'll have the ability to talk to his friends back home whenever he's bored or annoyed with the crew. They set off to their destination - it's a star 50 light years away. They're going to travel at a speed which will get them there in 60 years according to Earth, but thanks to time dilation the crew will only experience five. (I'm fudging the exact numbers because I can't be bothered to actually pull up the relevant tables; this is just a thought experiment.) Two and a half years into the trip - for Earth, 30 - Bob asks his friend Alice a question through the ansible. She's only experienced 2.5 years too. The question he asks is this: "What do the projections look like? Do you think they'll develop and build warp drives in the next 25 years?" Note that outside, this date (27.5 years into the trip) has already passed. At the very moment he finishes the question, up along side his ship pulls a brand new human warp ship. This ship is on its first test flight; it was just completed a couple of hours ago in a spacedock in orbit around the Earth. The captain of the warp ship - Charlie - spacewalks over to Bob's ship and they sit down to a nice lunch. Charlie catches Bob up on all of the developments back on Earth. Alice gets married, has three kids, and moves to the Moon. Bob accidentally left the ansible on, so Alice listens in on the conversation. Eventually she asks Charlie - who is momentarily startled by the disembodied telephone voice - whom it is that she marries. Charlie tells her that in six or so months, she meets a man named Dan, they fall madly in love, and they have a child whom they name Charlie. Charlie grows up to be a world famous test pilot, but to be honest he's not all that happy with his career. He tells Alice - who has, by now, realized that she is his mother - to try to convince him to be a poet instead. She does as he wishes. Unfortunately, this means that Charlie is no longer aligned to be the ship's test pilot, which means that he never catches up to Bob and has the conversation with Alice, which means that he becomes a test pilot anyway. And the universe goes kaboom.

I can't figure out any way to break this scenario and keep both warp and wormholes. Charlie isn't a wormhole himself; there's no path to take out with an army of infinite photons. Charlie's made of matter, just the same as Bob. There's no way to deal with Bob and Charlie's paradoxical lunch - well, other than saying that time travel is fine, but as much fun as that would be, this project involves a sort of multiplayer space sandboxy element, and implementing time travel in a multiplayer simulation is quite literally impossible without having access to real time travel in the first place. The best solution I can come up with is to just break wormholes; according to my universe, wormholes can't move. Either moving them takes infinite energy, or it makes them evaporate.

This, unfortunately, makes wormholes pretty useless, which made me quite sad for a while until I stumbled on a solution: don't make the wormholes move at all.

Alderson Points

The Alderson Drive was originally worked out by the JPL physicist Dan Alderson at the request of his friends Larry Niven and Jerry Pournelle who were working together on a book called "The Mote in God's Eye". It involves finding these naturally existing points of "equipotential thermonuclear flux," which is really just technobabble for "we stuck these wherever the plot demanded." When the drive is activated at one of these points, the ship transits between them instantaneously. Alderson points are, as far as the mechanics of use go, basically a naturally existing variant of a stargate.

Of course, most technobabble is as good as most other technobabble, so I took the opportunity to rework the drive mechanics to both enhance ease of use and try to prevent any annoying time machines from appearing.

In relativity, there are three kinds of distances. This is because two events can be separated by both time and space. Lightlike distances are distances which are exactly what light can travel along; if two events are a lightlike distance apart, then the one in the past can send light to the one in the future. Spacelike distances are farther apart in space than lightlike distances. You'd have to travel faster than light to get from one spacelike event to another. For an example, say that two planets decide they want to explode. If the events of them exploding are at a spacelike distance, you can't be in orbit around one as it explodes, then zip off and pull into orbit around the other one to watch it explode without at some point traveling faster than light. Note that this doesn't mean they happen at the same time, it just means that light can't get between them fast enough. (In fact, according to relativity even simultaneity isn't objective, but that's not overly important yet.) Finally, timelike distances are closer than lightlike distances. Slower than light signals - or objects, such as Bob's ship - can get from one timelike event to the next just fine without breaking any physics at all.

Naturally existing Alderson points, according to my formulation, must always maintain a spacelike distance. To do this, they must experience time at the same rate - thanks to gravitational time dilation, this means they must be at gravitationally equivalent points around stars. This gives them properties akin to Lagrange points; their positions are governed by the relative positions of the largest bodies in the star system (e.g. the Sun and Jupiter). They have to match nearby stars though, so they probably won't ever coincide with Lagrange points. Odds are they won't be on normal orbits at all. Instead, getting to points requires expending energy to "hover" at the point while you activate your drive.

Stars aren't exactly stationary relative to each other. They orbit the galactic center just like the planets that orbit them, and they orbit at different rates. When I asked StackExchange about it, they suggested that with careful positioning and controlling the amount of time it takes to "charge" a point, causality violations due to stellar motion could be avoided. This puts an effective range limit on the points (not a bad thing) and gives us our first concrete measure of the transit: the charge time between each specific pair of destinations.

For fun and faster transit, I decided that points should exist in networks. Every point in a network is connected to every other point. You select your destination by controlling how long you spend pumping energy into the point with the drive. Destinations that are farther away require longer charging times, but not by much. The networks naturally have centers and edges, and you can use them sort of like omnidirectional subway lines; star systems usually have 2-5 points in them, each connecting to a different network of, say, 15 points, so to get to a far away system you'll likely need to "transfer" a couple times.

When you shut your drive off, if the charging time matches what is required to get to a destination to within a minuscule tolerance, all matter within a certain range of the source and destination points is instantaneously swapped (instantaneously, in this case, is by the definition of the point network you're using). If the time doesn't match a destination, you just wasted a bunch of energy; for all intents and purposes, it disappears. (Really, you go somewhere, but the place you go is right back where you started.)

The radius of the swap is determined by how much energy you actually pumped in during that time. The easiest way to explain how this works is that at the end of the charging time the energy that was pumped in is distributed evenly through the swap volume sphere. The energy has a certain density which is constant and specific to each destination set (which is the second concrete measure of the transit). It's sort of like filling a balloon with water; you know how many liters/cups you're pumping in, and the balloon automagically "figures out" how big to get based on the density of water. When you pump in the first liter, the balloon inflates to a certain size, and when you pump in a second liter the radius doesn't double, the volume does; the radius only grows by about another 25%. You have to pump in a lot more water to get the radius to double.

It'd probably be annoying to be sitting around at a point trying to get to wherever it is you want to go when suddenly you discover you've been swapped over somewhere else that you didn't want to be by someone who was using the same point network. Fortunately the points naturally tell you when somebody is about to appear. While the drive is charging a point, both the source and the destination closest to the current energy level start to "glow." Spontaneous blue light (google "Cherenkov Radiation") starts appearing from all around inside the active radius. This tells you how big the ship is, and the intensity (which slowly builds) tells you where it's coming from and how long until it's ready to swap. This is useful on the ship's end too; it gives the crew an indication that the drive is, in fact, working properly. This effect can also be used to hunt for points, but given how close you have to get and how much energy it would take to run a drive constantly, it's usually easier to calculate the position of points mathematically.

In theory, what makes these points suitable for the swapping effect can be replicated artificially. This is how actual stargates (though they aren't remotely gate shaped) are constructed. There isn't enough physics here to work out how you would go about doing that though, so the current plan is to just say "oh, uh, the Precursors did it but they're dead so we don't know how any more."

Along a similar vein, a ship might be able to create artificial points within itself, allowing for a more powerful "go anywhere" jump drive. And given that an explanation for the swap effect that makes sense is that the points create a wormhole that only exists for an instant, it's plausible that some points could connect to parallel universes (i.e. hyperspace). But honestly, that sounds complicated, so I'm making it complicated and saying that those kinds of drives are rare and mythical, if not nonexistent. (Obviously this means players will encounter them regularly.)

Further reading: (Moved to Addendum II)

FTL Communication

Unfortunately, we now remember that throwing out movable wormholes eliminates my only lead on how to make an ansible.

No, quantum entanglement doesn't work. Quantum entanglement is basically like tearing a random playing card in half while blindfolded, sealing both halves in an envelope, giving one to a friend, and going really far away. When you open the envelope, you learn exactly what card your friend has - it's the same card - but you can't use this for communication because physics made you be blindfolded when you picked the card in the first place. It's great for encryption though; it's like a one-time pad that other people can't even look at or it gets erased 'cause quantum reasons.

We could try transporting photons through Alderson points, but why would you go through the trouble to do that when you could just send a hard drive instead? Well, it turns out this is perfectly analogous to a type of network developed in the early days of computing, and which is still used today, to some extent.

Sneakernet

Have you ever tried to send a file to a friend over the internet, only to discover that it would literally take longer than copying the file onto a flash drive, physically driving/flying to their house, and delivering it in person? As the saying goes in its various forms, never underestimate the bandwidth of a station wagon full of flash drives (or a milk jug full of MicroSD cards).

The idea behind an interstellar sneakernet is that cargo and passenger ships could be voluntarily fitted with electronic mail carrying equipment which would automatically download encrypted network data bound for the same destination before the ship jumps away. Once at the destination, the equipment would upload the data to the local facilities for sorting and storage, and the ship would receive a carrier's fee in return for their trouble. This gives an incentive for basically everyone to carry suitable hardware.

If you want to send a message to somewhere that's more than a jump away, you wrap it in multiple layers, each with an associated fee and destination. It'll take longer to get there, and it'll cost more, but it will definitely get there eventually.

This arrangement gives itself to the natural evolution of two types of systems which I have fondly termed the "Freelance Pony Express" and "Carrier Pigeons." Taking a ship on trade runs between common destinations (i.e. interstellar "coastal cities") could and likely would turn out a decent profit purely from the carrier's fee, so one could imagine ships designed specifically for this purpose - the Pony Express. Say you're a government or a business, and you don't want to put your traffic through the normal network for either security reasons or speed requirements - perhaps a message is urgent to prevent a war. You could send someone on your fastest ship, or you could send a small probe with a hard drive, which is smaller, lighter, and it can handle more gees on the way between connecting point networks. These probes work a lot like, and are analogous to, carrier pigeons. (Okay, they really aren't, but to anyone who hasn't done as much research as you or I, they are.)

Extra hardware space on most ships is still probably going to be limited (the tyranny of the rocket equation) so the sneakernet system will likely be programmed to pick and choose which messages to carry. People can increase their message's attractiveness by giving it a higher carrier's fee, but after a while the older messages will get picked up as well; cash is cash. The system to dispense the carrier's fee will have to be automatic to avoid fraud, and the going price for messages will probably self-regulate to be a little more than exactly what is required to make the trip worth it.

Further reading: (Moved to Addendum II)

If read that last bit closely, it sounds a lot like something else: Bitcoin.

Economy

You may ask yourself what the problem is with fiat currency, but really the question is "Why pass up an opportunity to overcomplicate something we take for granted?"

I really like the idea behind Bitcoin, and I hope it catches on majorly in the mainstream. So, as a worldbuilder, I'm in a position to say that that's exactly what happens. Everybody in the future uses a Bitcoin derivative. Sure, there are people - whole planets, even - that shun capitalism, but that doesn't matter; this section doesn't need to talk about them 'cause they've got their own system going on.

Bitcoin is, in many respects, an ideal currency system. New money is supplied automatically as part of the design of the protocol. It's difficult to modify - at least without majority consensus - which means you can depend on it staying fairly stable. However, because it depends on a protocol, and not a central authority, all of the nodes in a network have to agree that a transaction is valid for it to literally be valid, and they can only agree as fast as they can talk to each other. Without ansibles, this becomes a major problem at Earth-Mars distances, let alone interstellar distances. So if everyone uses bitcoin, each planet must therefore have their own, independent blockchain.

Now, here's a part that, for the moment, I'm completely stuck on. I'm not an economist. I have no clue how one would go about setting up interstellar exchange rates. The best lead I have is that you'd need some sort of authority on both ends which would sell you credits in a temporary "border" fiat currency, and then on the other end, accept the credits back and give you an appropriate amount in your destination system's bitcoin. This seems like it's extraordinarily vulnerable to fraud, though, so if anyone has a better idea I'd be happy to hear it.

STL Propulsion

Back to something I do know about. To get up to speed for Alcubierre drives, or to pull your ship out to a jump point, you still need to have some form of slower than light propulsion system. Star Trek solves this with impulse engines, but they're just glorified photon drives, and are therefore total bunk. Instead, we're going to use reactionless drives, which violate the law of conservation of momentum, and are therefore total bunk.

But First,

Before we get there, I want to hit on some things which are not total bunk. Namely, matter-antimatter reaction drives. (Yes, you in the back with your hand up, regular old chemical rockets are still a thing, but they're boring so as far as this post is concerned I'm taking them for granted.)

If you're familiar with rocket science - and I mean, pfft, who isn't - you know that there's this nasty little bugger called the Tsiolkovsky Rocket Equation. It's this little piece of math which is total bunk which says that because you need fuel to make your rocket go places, you also need fuel to make that fuel go places with your rocket, and that fuel needs even more fuel, and so on. Randall Munroe, creator of the webcomic XKCD, ran face first into this problem when he tried to design a model rocket which could get to orbit and the math told him to assemble a mile-wide gunpowder pancake with a 10-meter peak in the middle. ("Weird hill. So, where's your spaceship?") It goes without saying that the rocket equation causes many engineers much trouble.

In more concrete terms, the rocket equation says that the amount of speed change a given rocket is capable of (delta velocity, or Δv) is determined by the mass of your rocket (sans fuel), the mass of your fuel, and the velocity of the fuel when it leaves your rocket. To make your rocket go faster, you optimize these pieces; you make your rocket as light as possible, but give it a metric butt-ton of the most explosive fuel you can drum up. In other words, you give it antimatter.

"But Adam!" I hear you say. "Antimatter is really hard to create, and even if you have the proper facilities you can only expect a maximum 50% efficiency because when you create antimatter, you also inevitably create normal matter!" To which I reply, "Shut up." We create antimatter anyways because it's cool. So deal with it. (This is expanded down in the section on power. Also, as a general counter to the 50% point, what, exactly, were you planning on reacting with the antimatter to get the energy back out? Parts of your ship? Redshirts? I thought not.)

But there's another way to get around the rocket equation: don't carry fuel. If you know your sci-fi, you may be thinking I'm leading up to Bussard Ramjets. Nope. I'm leading up to their hot younger sister, the Valkyrie.

You know that ship from the beginning of Avatar? That's a Valkyrie. Sort of. Let me explain. Dr. Charles Pellegrino and Dr. Jim Powell looked at the designs for Bussard Ramjets and smugly thought to themselves, "Heh. We could one-up that." They came up with a design that is basically a spaceship on a string, compared to the more...beefy hardware on a ramjet. Plus, their design had the engine in front, unlike other designs which they said "put the cart before the horse." The Valkyrie is capable of speeds up to 92% of the speed of light, starting with antihydrogen triggered fusion up to 12% of the speed of light, followed by direct antihydrogen-hydrogen annihilation. This sounds "meh" until you notice that, to get all the way up to 10% of the speed of light (30 million kilometers per second), it only needs a mass ratio of 1.5 - that is, only 33% of your rocket needs to be fuel. That's, like, impossible rocket wizardry right there. By comparison, the space shuttle, which could only just barely get into orbit, had a mass ratio of 16 (i.e. it was 15 parts fuel, 1 part not).

Valkyries are, barring warp drive, the most feasible real-world interstellar ships I have seen yet. Bob's ship, in the wormhole time travel story above, was probably a Valkyrie. Dr. Pellegrino served as a scientific consultant on Avatar, which explains the ship; it's basically a Valkyrie, but artsier. It's kind of a big deal, but nobody seems to have heard of it, which confuses me. Anyways.

Electrolysis

Water is a beautiful thing, you know that? You can drink it, cook with it, bathe in it, grow stuff in it, swim in it, use it to protect yourself from harmful ionizing radiation, light it on fire and blow stuff up...

Oh, what? "Water and fire don't mix, silly!" You, my friend, have been misinformed. Water loves fire. In fact, fire is one of the ways water was made in the first place. Just take two molecules of hydrogen for every one molecule of oxygen, provide a little activation energy (i.e. heat) and BAM! Suddenly you have massive energy release in the form of lots of piping hot steam.

See, water is what we call a "low energy state" - it's very, very stable. Hydrogen and oxygen gas, on the other hand, are not. If you give them the slightest excuse, they'll happily jump ship and recombine into water, throwing off their extra energy as they go. This is really nice, 'cause it means we can use it to power rockets. In fact, that's all that was in the late, great Space Shuttle's giant orange external tank: supercooled liquid hydrogen and liquid oxygen. That's why you could barely see anything coming out of the main engines; there was no polluted exhaust to make hot glowy smoke because all that was coming out of them was pure steam. (The SRBs, on the other hand, were burning fuel with a mixture of an Aluminum compound, so the Aluminum was plenty visible.)

It's fairly easy to go the other direction, too, if you want. All you need is electrical energy (via solar panels, perhaps) and a suitable anode and cathode and you can get out fresh hydrogen and oxygen to breathe and/or explode out the back. (Theoretically you can get hydrogen peroxide too, which is useful in monopropellant thrusters, but that's more complicated to explain.)

Now, if you've got yourself a ship with people on it, and you aren't a sadistic madman, you've probably got some water on there to bathe in and subsequently drink. For short, relatively low Δv interplanetary jaunts, why not double your money and use it for fuel too?

But that's enough of that. On to the really crazy stuff.

Cannae Drives

You probably saw the news fiasco a while back when it was revealed that NASA is testing a supposedly impossible thruster design and getting positive results. The drive design they were testing, which goes by many names, claims to (and by all accounts, appears to) produce a net force without ever releasing exhaust. The best way to explain this is to liken it to a propeller on a submarine; a submarine doesn't carry water with it to shoot out the back because it can just use a propeller to push water backwards, accomplishing the same goal.

The thing is, while that makes sense for a propeller, it completely clashes with the way we're pretty sure physics works. The propeller actually has stuff to push against - the water - but in space all you've got to push off of is nothing, which is exactly as hard as it sounds. If it's possible, it could mean that all three of Sir Isaac Newton's laws of motion are flat out wrong. For every action there's an equal and opposite reaction? Where's the opposite reaction to the Cannae Drive?

You might just think that, because it takes in electrical energy and gives out force, and because technically we're making science fiction anyways, we could define a theoretical efficiency (e.g. 1 newton per watt) and be done with it, but thanks again to freaking Einstein, that's not an option. The math says no. Basically everyone would disagree on the efficiency because the units make no sense. If you're familiar with how SI base units work, you'll find that newtons per watt reduces down to seconds per meter, which, I mean, wat. That's not helpful in the least. It's like how miles per gallon is actually length per length³ - length² (which I guess is technically still physically meaningful; it's the cross section of the tube you'd get if you laid out your fuel evenly along the path you took, but whatever).

Yet the fact remains that for now the drive appears to work. The inventor, China, and NASA all tentatively agree on that point. So something must be going on - and it's not atmospheric; they've tested it in a vacuum chamber now, so it's got a leg up on other designs from the past.

The most promising operational theory for now seems to be Harold White's (yes, this is the warp drive guy). He thinks that somehow - and, I mean, this is my interpretation of his interpretation of some deep magic, so it may be completely off - the microwaves pumped into the frustum chamber add up sort of like a laser and then somehow that pushes off the very fabric of the universe in the form of "quantum vacuum virtual plasma" which is a version of the quantum foam theory we touched on in the wormhole section above. I think this means you could basically say that there is, in fact, a reaction mass, it's just that the mass is practically infinity because it's the whole rest of everything.

His theory depends on and builds off of a lot of things. I'm not sure how it gets this far, but apparently it successfully predicts the Bohr radius of all of the elements up to Nitrogen (and they didn't go further because the math was getting too hard and they just wanted to publish the paper already) so even if it doesn't end up being right about the drive there's probably something to his theory in other directions.

One nice thing about reactionless drives (beyond the fact that all they need is a power source to run indefinitely) is they have no exhaust, so you can stack them all throughout your ship; they don't need to be on the back or even the outside. They can be in the inside walls, as long as they're thick enough. The Cannae drive design (minus the supporting circuitry) looks a lot like a pancake with a point or a flattened Hershey's Kiss or whatever, so as long as the space is wide enough for the diameter, it's probably thick enough for the... thickness...

Space Habitats

Instead of retyping everything for this section, I'm just going to link you to the research paper I wrote for my English class final this semester. ahov.co/artct (PDF)

One thing that didn't make it into my paper, however, was the small web app that I wrote to calculate some things about artificial gravity. That's here: ahov.co/spin

Questions

I had a whole list of questions I'd pulled out, but they all boiled down to these three: are there inconsistencies or unintended consequences (e.g. more time machines), are there ways to game the system, and did I forget anything? Any questions, comments, and suggestions that don't relate to those questions would also be greatly appreciated though.

There are three more sections I'm currently writing (weapons, power, and space habitats), but honestly I've been sitting on this for more than a month so I figured I'd post what I have and then follow up when they're done. I want to put a lot of research into this, but school is starting to ramp up for finals and such so...

If what we're doing here overlaps with/stands a chance of overlapping with your own specific personal area of expertise, then by all means, ask, and I'll write up what we have so far in that area so you can nitpick and make sure we get it just right. I'm being completely serious. We want to get this right.

You may notice a lack of stuff about politics, history, and aliens. That's because I'm not in charge of that part. Well, I am, but I've got other people doing most of it. They seem to have it handled for now. If you have any suggestions for them, though, I'd be happy to pass them along.

Addendum

In the interim between writing most of the content here and actually posting it (i.e. nitpick buffer time), I came up with a concept for what the physics behind the Alderson Point drive described above could be. It's not much, but if anyone wants me to, I could write up a description. (Note: Currently, learning how they work might count as a spoiler because it naturally lends itself to one of the major plots we've worked out, so if the stuff above sounds like it could lead to something you'd like to read/play, you might not actually want to know until we're done.)

Also, how did you like the writing style? Was it mostly/entirely understandable? I tried to keep it approachable; I'm going to need to figure out a way to efficiently explain the concepts here to, on the lower end, mildly intelligent Streamers, so I'd appreciate any tips you have.

Addendum II: Further reading?

Most of my Further Reading links disappeared. I must be a spammer.

• http://physics.stackexchange.com/questions/172699/the-effect-of-multiple-alcubierre-rings
• http://worldbuilding.stackexchange.com/questions/9029/can-this-version-of-the-alderson-drive-be-used-to-violate-causality
• http://worldbuilding.stackexchange.com/questions/9894/how-long-can-the-physics-behind-a-technology-go-unexplained
• http://stackoverflow.com/questions/28639028/automatic-message-routing-on-a-sneakernet
• http://worldbuilding.stackexchange.com/questions/10601/interstellar-internet-use-cases-or-what-if-the-internet-was-mail-order

Edited April 30, 2015 by AdamHovorka
Added artificial gravity calculator thing.

[Lethosos]

There's some good articles about space habitats out there--the best ones I've seen work on 3 to 4 tiers of complexities. (My favorite, an O'Neill colony, is classified as a tier 2 space habitat.) Feel free to consider the resources needed to make a Ringworld (tier 4,) of course.

[AdamHovorka]

Some designs I've been eyeing are Kalpana One and asteroid core paraterraforming; apparently long O'Neill cylinders, while pretty, are rotationally unstable. Anybody moving around on the inside can make it tumble, so to avoid that they can only be about as long as their diameter. Oh, and we've got something even better (read: more insane) than a ringworld, but I'm keeping it a secret until the big reveal in our "archive" webseries project.

Deciding on the placement of the stations is fun too. Obviously we've got Lagrange points, but have you ever heard of Cyclers?

Edited April 9, 2015 by AdamHovorka

[Dentcat]

Transoscillatory soundwave stacking. Using a similar function to a beam of light in a mirrored ball. However, sound is created by kinetic forces, and thus has more effect. If a theoretical container was created, wouldn't it be hypothetically possible to hone compressed soundwaves into further kinetic function? You could at least build a generation ship like that.

If matter and antimatter are exact opposites, antimatter will stretch time in the opposite way of matter. Thus, negating an amount of matter would allow infinitely fast travel.

I prefer the idea of generation ships. More feasible. I was thinking, what if a wood burning engine was to be implemented, powered by gengineered bamboo? Bamboo can grow VERY fast. Genetically engineer that to create compounds similar tosolid fuel, and you can fly at about 100mph for pretty much ever. Until you have no water left.

[AdamHovorka]

Transoscillatory soundwave stacking. Using a similar function to a beam of light in a mirrored ball. However, sound is created by kinetic forces, and thus has more effect. If a theoretical container was created, wouldn't it be hypothetically possible to hone compressed soundwaves into further kinetic function? You could at least build a generation ship like that.

​See, that's why the problem of reactionless drives is so difficult. Your idea sounds fine in theory, but really it's the same as jumping off the front of your ship to give it a propulsive force; it works until you hit the back wall, at which point the kinetic energy is transferred back in to the ship and it stops moving. The center of mass of both you and your ship never actually moves.

If matter and antimatter are exact opposites, antimatter will stretch time in the opposite way of matter. Thus, negating an amount of matter would allow infinitely fast travel.

​There is a version of antimatter theory which holds that it travels "backwards" through time, but it's not really a "field"; it's more like someone made entirely of antimatter would perceive time as running in the opposite direction. "Negating" regular matter with antimatter would, however, allow really fast travel, it's just that you wouldn't be "you" any more; you'd be a cluster of gamma rays.

I prefer the idea of generation ships. More feasible. I was thinking, what if a wood burning engine was to be implemented, powered by gengineered bamboo? Bamboo can grow VERY fast. Genetically engineer that to create compounds similar tosolid fuel, and you can fly at about 100mph for pretty much ever. Until you have no water left.

​Bamboo needs more than just water to grow, though; the stalks aren't created out of thin air. You'd need to bring along soil and fertilizer and extra air, and by that point it weighs a whole lot more than just taking along prefab fuel. Taking just the water on the other hand, well, *looks up and sees he forgot to put in a bit about electrolyzed fuel* Oh. Hmm. Let me edit that in.

Edited April 10, 2015 by AdamHovorka

[TheBytemaster]

I really love the writing style. The humor is great, helps keep interest. I can't see any immediately obvious loopholes or anything, but I do have to wonder what would happen if you were to warp with an Alcubierre Drive through an Alderson point right as it was triggered from the other side.

[AdamHovorka]

I really love the writing style. The humor is great, helps keep interest. I can't see any immediately obvious loopholes or anything, but I do have to wonder what would happen if you were to warp with an Alcubierre Drive through an Alderson point right as it was triggered from the other side.

​If you were to be warping right at the right point when it went off, your ship would swap over to the other side leaving you still warping, yet disoriented. I'm not quite sure what happens around the edges of the swap space, but if there's a size difference you may end up with only half a ship.

If you're on the other side of the equation, you'll pop through into the shadow of a warp field which could possibly move you on the order of tens of meters before dissipating. If, again, there's a size difference, you may end up having part of your ship try to warp into another part, with effects just as deadly as that sounds. Some of your hull may overlap with the field's edges, leaving that part to be stretched or shrunk, depending on what part of the field you're in. And finally, if you're lucky (and your victims weren't) you may end up with parts of a warp ship conveniently placed for you to loot.

The odds of this ever happening in practice, however, are nigh incalculable. Space is big.

[Lethosos]

Some designs I've been eyeing are Kalpana One and asteroid core paraterraforming; apparently long O'Neill cylinders, while pretty, are rotationally unstable. Anybody moving around on the inside can make it tumble, so to avoid that they can only be about as long as their diameter. Oh, and we've got something even better (read: more insane) than a ringworld, but I'm keeping it a secret until the big reveal in our "archive" webseries project.

Deciding on the placement of the stations is fun too. Obviously we've got Lagrange points, but have you ever heard of Cyclers?

​Not if you provide rotational masses on the outside. Laws of inertia is still in effect, y'know. You can still get away with an O'Neill colony simply by adding a stabilization ring around the middle, like a pueso-gyroscope. That being said, toroid designs are still worth looking into as well. Oh, and that comment about something better than ringworlds? I already have a good idea about what you're talking about; I've looked at interesting variations on that (my favorite being one regarding both power and data systems; I'm not gonna spoil it.)

Never heard of Cyclers, but playing space physics games showed me some bizarre perpetual momentum behaviors that resemble this.

Edited April 11, 2015 by Lethosos

[AdamHovorka]

Oh, and that comment about something better than ringworlds? I already have a good idea about what you're talking about; I've looked at interesting variations on that (my favorite being one regarding both power and data systems; I'm not gonna spoil it.)

​Based on that, no, I don't think you do, but we're going to use those too.

[Doctor_Chuckles]

alright ill be honest. you lost me when you started this thing! but who cares because it all strangely makes sense. for one, im not old, two, i dont know all or ever much of quantum mechanics and other quantum strangeness. but ive an open mind and i learn fast. ive got to ask, could you really do this? with the Bitcoin thing, you could have a universal coin/currency and then, according to the currency in the place you need it, there is an exchange rate just like we have here on earth. yes, this is open to fraud. but arent  all other currency systems? there could also be some form of confromation sheet form the place this money comes from.

[Doctor_Chuckles]

oh and, on fuel, one could use a fuel that might commonly be found on asteroids and other things like that. in space, you dont need a whole lot of force to get moving either, as there is nothing to apply friction or another force back at you. beside gravity, but thats too much for me to care about. on this, you could have a constant, and growing speed. find your own way to steer it, as i cant think of one.

 

this is an edit, but i just want to say i probably used the wrong steer, but you hopeful know what i mean

 

Edited April 11, 2015 by Doctor_Chuckles
idk

[Doctor_Chuckles]

​If you were to be warping right at the right point when it went off, your ship would swap over to the other side leaving you still warping, yet disoriented. I'm not quite sure what happens around the edges of the swap space, but if there's a size difference you may end up with only half a ship.

If you're on the other side of the equation, you'll pop through into the shadow of a warp field which could possibly move you on the order of tens of meters before dissipating. If, again, there's a size difference, you may end up having part of your ship try to warp into another part, with effects just as deadly as that sounds. Some of your hull may overlap with the field's edges, leaving that part to be stretched or shrunk, depending on what part of the field you're in. And finally, if you're lucky (and your victims weren't) you may end up with parts of a warp ship conveniently placed for you to loot.

The odds of this ever happening in practice, however, are nigh incalculable. Space is big.

​yes the odds are small but so are the odds of millions of things that have happened, so this is bound to happen anyway. you say there is the wierd glowy stuff that apears when somebody is coming. so if you were instead of at the exact time as each other, but at near enough times, you could stop your drive, waste a load of power, but hopefully live.

[AdamHovorka]

ive got to ask, could you really do this? with the Bitcoin thing, you could have a universal coin/currency and then, according to the currency in the place you need it, there is an exchange rate just like we have here on earth. yes, this is open to fraud. but arent  all other currency systems? there could also be some form of confromation sheet form the place this money comes from.

​I suppose the analogy is there, but one of the unique things about Bitcoin is how it removes the need to trust the issuing entity entirely; the value of the money is determined by everyone that runs a node. I figured that if that's possible on a local level, there must be a way to rework it onto a universal scale. It's just a matter of ping time...

oh and, on fuel, one could use a fuel that might commonly be found on asteroids and other things like that. in space, you dont need a whole lot of force to get moving either, as there is nothing to apply friction or another force back at you. beside gravity, but thats too much for me to care about. on this, you could have a constant, and growing speed. find your own way to steer it, as i cant think of one.

​That's why electrolyzed fuel is so great for interplanetary travel. If our solar system is any indication, water likes to clump up in asteroids and comets during system formation. There's a company called Planetary Resources that's already trying to create a system to get at them. And if the investing opinion of Larry Page, Eric Schmidt, and James Cameron is anything to go by, I think they can do it. The current going price for getting one liter of water into LEO (Low Earth Orbit) is around $20,000, so if they can do it for any less than that they'll be making bank.

​yes the odds are small but so are the odds of millions of things that have happened, so this is bound to happen anyway. you say there is the wierd glowy stuff that apears when somebody is coming. so if you were instead of at the exact time as each other, but at near enough times, you could stop your drive, waste a load of power, but hopefully live.

​Well, yeah, that's what I was saying; it's not impossible, but it's easily avoidable if the pilot / navigational computer of the warp ship knows what they're doing. To put it in perspective, this happening by pure chance has worse odds than you getting struck by lightning the very instant you successfully hit a specific key on your keyboard with a bb gun... all the way from Saturn.

Edited April 12, 2015 by AdamHovorka

[Doctor_Chuckles]

 

​Well, yeah, that's what I was saying; it's not impossible, but it's easily avoidable if the pilot / navigational computer of the warp ship knows what they're doing. To put it in perspective, this happening by pure chance has worse odds than you getting struck by lightning the very instant you successfully hit a specific key on your keyboard with a bb gun... all the way from Saturn.

​from Saturn, i must say you have a better change warping at the same time. but anyway, i see where your coming from. on fuel, you said there were electric engines right? because i think i have an idea for an electric generator that runs off of itself, for ever until it is broke or stopped. so say my idea works, you could have infinite fuel (electricity) until the generator would be stopped for some reason. if anything in my idea doesnt work, this is all a load in bunk.

[Doctor_Chuckles]

 

​Well, yeah, that's what I was saying; it's not impossible, but it's easily avoidable if the pilot / navigational computer of the warp ship knows what they're doing. To put it in perspective, this happening by pure chance has worse odds than you getting struck by lightning the very instant you successfully hit a specific key on your keyboard with a bb gun... all the way from Saturn.

​from Saturn, i must say you have a better change warping at the same time. but anyway, i see where your coming from. on fuel, you said there were electric engines right? because i think i have an idea for an electric generator that runs off of itself, for ever until it is broke or stopped. so say my idea works, you could have infinite fuel (electricity) until the generator would be stopped for some reason. if anything in my idea doesnt work, this is all a load in bunk.

ok, i dont know how this got up here twice, but i cant take it down so, yeah

Edited April 12, 2015 by Doctor_Chuckles
i

[AdamHovorka]

​from Saturn, i must say you have a better change warping at the same time. but anyway, i see where your coming from. on fuel, you said there were electric engines right? because i think i have an idea for an electric generator that runs off of itself, for ever until it is broke or stopped. so say my idea works, you could have infinite fuel (electricity) until the generator would be stopped for some reason. if anything in my idea doesnt work, this is all a load in bunk.

The relative sizes of the bb, key, and Earth-Saturn distance are more favorable than the warp-jump edge case by a couple of orders of magnitude. Like I said, space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space...

A generator that runs off itself is called a "perpetual motion machine," and they're, unfortunately, completely impossible as explained by the laws of thermodynamics.

Edited April 13, 2015 by AdamHovorka

[Doctor_Chuckles]

in any laws of anything does it say you cant run, i don't know, 3 generators on one shaft? if so, my idea is, as i said, bunk. if not, my idea is still good. but, with shooting a key from Saturn, say your shooting the "B" key. if you did hit it, chances are your whole computer, and a decent area around it, would be completely decimated. also, just saying, Saturn can not be stood on, rather in. could you time travel if you were sent at speeds over 20x (which may be exaggerated) the speed of light in one direction? or would you just be completely and painfully destroyed?

 

Edited April 13, 2015 by Doctor_Chuckles

[AdamHovorka]

in any laws of anything does it say you cant run, i don't know, 3 generators on one shaft? if so, my idea is, as i said, bunk. if not, my idea is still good.

​No, having multiple generators along one shaft isn't against the laws of physics, but electromechanically they will reduce down to just one. As for whether that would allow you to create some kind of feedback loop, bear in mind that energy can be neither created nor destroyed (first law) and it will trend toward entropy (second law). If you'd like to share your design in more detail, I can help you find the flaw.

but, with shooting a key from Saturn, say your shooting the "B" key. if you did hit it, chances are your whole computer, and a decent area around it, would be completely decimated. also, just saying, Saturn can not be stood on, rather in.

​It's... an analogy...

could you time travel if you were sent at speeds over 20x (which may be exaggerated) the speed of light in one direction? or would you just be completely and painfully destroyed?

​According to the Special Theory of Relativity, travel at even 1c (the speed of light) is impossible for anything with a positive rest mass. Photons, with a zero rest mass, always travel at the speed of light no matter what (and you'll measure them as going that speed no matter how fast you yourself are going, 'cause physics). Particles with an imaginary rest mass, which we call Tachyons, always travel faster than light, but as of yet we've never seen them in real life so good money says they either don't exist or they're really really hard to detect.

If you were to attempt to go 20c, and had a non-zero acceleration time, what you would see for the first, oh, ten million meters per second would be fairly normal. At around fifty million meters per second, if you looked out the window, everything in front of you that we here on Earth see as red would look like it was green, and everything behind you that was supposed to be blue would look orange thanks to the Doppler Effect (the same reason car horns passing you suddenly drop in pitch, i.e. the BEEEEEEEEWwooooooo). At two hundred million meters per second, everything around you (if you can manage to see more than a blur before you pass it) will seem to be experiencing only one minute for every minute and a half you count off (and they'd see the the opposite - they'd say you're the one slowing down). At around 250 million meters per second you start to notice that the rest of the universe is shrinking in the forward direction; things look like they're only about half as thick as they should be (and again, anyone else would say the same exact thing about you).

Now, note that this whole time you think you've been accelerating steadily at, say, a whopping 20 gees (which, FWIW, as a biological human, you could absolutely not survive). According to you, this trip has so far taken about two weeks. But everyone else says it's taken a lot longer. See, for them, you stopped accelerating at the full 20 gees a long time ago. At this point it looks like you're only accelerating at about 10 gees thanks to that same pesky forward contraction. Another 30 million meters per second later and you'll look like you're only pulling about 8 gees. Another 15 million and you'll only be pulling 3. I think you see where I'm going with this. It's a real life example of Zeno's Paradox; if the closer you get, the slower you go, you'll never actually reach your destination. Physics just won't allow it.

So unfortunately, going 20c is impossible. (That is, unless you pull some other magic out of your hat as in the FTL section above, but I've made pretty sure they aren't time machines either. Sorry.)

Edited April 14, 2015 by AdamHovorka

[Doctor_Chuckles]

i get that all. and i can not think of anything else to say either.

[AdamHovorka]

*Bump*

Just added the "section" on space habitats. 17 pages of new text, if I were to have copied the PDF in, but I didn't 'cause that would have been... y'know...

Again, reviews, comments, rants, etc. are greatly appreciated.

Edited April 30, 2015 by AdamHovorka
Tried to make sure this didn't seem "low effort."

[TheBytemaster]

*Bump*

Just added the "section" on space habitats. 17 pages of new text, if I were to have copied the PDF in, but I didn't 'cause that would have been... y'know...

Again, reviews, comments, rants, etc. are greatly appreciated.

​That's a good, pretty comprehensive read. Not too heavy, good writing style.

My only question is this; What kind of rotation speeds/diameter would a space-station need to maintain between 0.9-1 G? Is that size/speed range obtainable with current or near-current tech? (Without just tacking on the word "nano" to hand-wave the material strength problem.)

[AdamHovorka]

My only question is this; What kind of rotation speeds/diameter would a space-station need to maintain between 0.9-1 G? Is that size/speed range obtainable with current or near-current tech? (Without just tacking on the word "nano" to hand-wave the material strength problem.)

​I'm glad you asked! I actually wrote a small web app to calculate that stuff, and forgot to stick it in here! ahov.co/spin

As far as material strength goes, 1g is well within current material strengths; everything we build here has to withstand at least that much just from being on the surface. The rim is closely analogous to some types of bridges, and the spokes—well, I can't think of an analogous structure off the top of my head, but we're good up to at least 250m as seen in the Kalpana One station designs. (Mental simulation suggests we're good indefinitely; it's only 1g at the rim, and fades out towards the center, but I don't have any math to back that up right now.)

[TheBytemaster]

​I'm glad you asked! I actually wrote a small web app to calculate that stuff, and forgot to stick it in here! ahov.co/spin

​Of course you did. Wait a second, now I remember that thing from somewhere....

That's the thing I helped test forever ago isn't it.

As far as material strength goes, 1g is well within current material strengths; everything we build here has to withstand at least that much just from being on the surface. The rim is closely analogous to some types of bridges, and the spokes—well, I can't think of an analogous structure off the top of my head, but we're good up to at least 250m as seen in the Kalpana One station designs. (Mental simulation suggests we're good indefinitely; it's only 1g at the rim, and fades out towards the center, but I don't have any math to back that up right now.)

​Oh, right. Duh. *facepalm*

 

EDIT: Now I have a strange desire to design some sort of terrorist space-drone fleet that would attach to said space station and accelerate it until it hits lethal g-forces and/or flies apart.

Edited April 30, 2015 by TheBytemaster

[AdamHovorka]

Now I have a strange desire to design some sort of terrorist space-drone fleet that would attach to said space station and accelerate it until it hits lethal g-forces and/or flies apart.

​And that is why the next section I'm working on is weaponry and defense.