Nova Roma: consequences of sundiving and stutterwarp

[Adam Dray]

This is a thread to tease out unexpected consequences of me changing how spaceship travel works IMTU (Nova Roma).

Here's the synopsis of the technology.

Bubble
A ship creates a bubble around itself. The sphere remains in normal space (it doesn't reduce to a point) but warps light and space around it. Maybe it does weird gravitic things, like flinging light around it like a black hole.

Inside the bubble, the ship is basically in its own universe. There's nowhere for heat and gas to go. EM radiation doesn't get in, either.

The ship can oscillate the bubble. It does this to let in enough EM to run sensors.

Hackdrive
Using large amounts of energy, the ship can take advantage of "rounding error" in deep physical properties at the boundary between macro relativistic (continuous) effects and quantum (integer) effects. Handwavey stuff.

This is like a "hack" against the universe. It allows the ship to shift the bubble forward a tiny amount. By oscillating this effect very, very fast, the ship can translate its movement in any direction. This is not normal motion. It is truly a "cheat" of the universe and it is free of momentum. The ship can make perfect right-angle turns, for example, or (even more dramatically) reverse direction without a change in speed. UFO-stuff.

Current H-drive speeds are not FTL. The typical military hackdrive can navigate a 1 AU (1.5 x 10^8 km) distance in about 6 days (at a constant speed of just less than 0.1% c), so it would take 30 days for the same ship to reach Jupiter from the Sun.

A trip to Alpha Centauri, if there were anything interesting there, would take 44 years.

Ships often have a backup M-drive (typical reaction mass drive) for emergencies.

Power Plants
Current military starships use fission reactors. There are two, but only one is needed to supply sufficient power to the drives. They replace the nuclear fuel material every couple years.

Let's assume very, very efficient power generation. It's water-cooled steam generation, but somehow close to 99% electrical power conversion. That still produces a lot of waste heat that gets stuck in the bubble. It could be vented into space if the bubble is down, but that stops forward motion during venting. During battle (which really hasn't been a problem for Nova Roma, since they haven't met a serious interstellar enemy yet), no one wants shields down, so heat is an issue. Also, see below (sungates).

Bubbles are not perfectly impervious to the outside universe, but it takes a lot to break the barrier. Nuclear weapons will do it. A direct hit of plasma from a solar flare or other Sun-generated blast can do it.

Sungates
Astrophysicists discovered artificial wormholes in the Sun. They sent unmanned probes through them but lost contact with the probes. Almost a decade later, they picked up their signal from a nearby star. Mankind then asked for volunteers for the first manned mission through the wormhole, which they called a sungate.

Sungates are about 1 km in diameter and they're well hidden. To enter one, you must simply pilot your ship into them, dodging solar flare activity and other destructive forces, with a minimum of sensory data. Every time you take a sensor reading, you must drop your protective bubble long enough to let in enough light and other radiation. This causes you to take on heat. The last 30 seconds of the journey are usually done completely blind, so you aim the ship as best you can and pray. The Sun can produce forces that tear through a ship's bubble, but intense damage is more common than disintegration.

The wormholes are uni-directional but paired. That is, once you get to another star, you don't know how to get back until you discover the location of the paired wormhole. You're equally likely to find a wormhole to a new star as you are to find one back. Science teams ride along on all exploratory missions and it takes them months, even years, to find a way out of a new system.

 

[Adam Dray]

Ship Design
The prohibitive cost is the bubble. Let's say that cost increases linearly with diameter AND with the mass inside.

If you want to generate a bubble around a 500 Td ship, you'll also want that ship to be as compact as possible. Round (spherical) shapes are best for travel but more difficult for people to work in, so some kind of flattened spheroid is more common.

Flatten it out more to make it vaguely aerodynamically streamlined in case it has to make an emergency landing, old school style.


Skipping
How fast can a starship move from one star to another along established sungate routes?

In the OTU, ships take a week to travel a parsec. In Nova Roma, the jump through the sungate takes a few minutes. The bulk of the remaining travel time is spent travelling from the star to a destination planet (and, conveniently, that takes about a week).

But what if you have an established route of sungates from star A to star B to star C to star D and you want to do it quickly? What stops you from doing that in one day?

First, you need enough coolant to make four sungate entries. Ships carry liquid ammonia coolant and blast the heated gas into the vacuum between the hull and the bubble. (The bubble becomes part of the ship, really. The metal hull can be considered the "inner" hull, and the bubble is the "outer" hull. Why not use that space between to vent hot gas?)

The standard ship design carries enough coolant for one jump, but there's no reason you couldn't design for several.

You could also put some kind of space station on the dark side of Mercury (0.4 AU) and speed up your trip to 2-3 days each way.

I guess I'm looking for something I can throw in there as a constraint to slow down travel. Mass of the coolant will impact the size of the bubble generator required. Perhaps mass also impacts speed of the hackdrive. The less mass you have in the bubble, the faster you can hack the mass forward in space. Carry too much coolant, and you'll slow yourself down too much to survive the sungate entry, regardless of how much coolant you're carrying.

 

[HG_B]

Bubble
Inside the bubble, the ship is basically in its own universe. There's nowhere for heat and gas to go.

Your ship and crew will have a very short half life. They will soon melt... Think fusion powered oven with almost perfect insulation.

 

[Adam Dray]

So let's assume there's some limits on how many stars you can visit in a single hop without flying out to a starbase somewhere and refilling your coolant.

What are the political, social, economic, military, and technological consequences of all of this? What is going to be very different from the Traveller OTU?

 

[HG_B]

So let's assume there's some limits on how many stars you can visit in a single hop without flying out to a starbase somewhere and refilling your coolant.

Coolant won't help as there is no place for the coolant to MOVE the heat to. (Coolant is a heat mover. There is no place in your set up to move the heat TO)

Your ships would melt in a time increment measured in minutes or a VERY few hours, not days.

 

[McPerth]

Have you taken the idea from Starfighter or Imperial Starfighter?

The idea of warp points (or wormholes) and STL constant speed in system travel reminds me of it.

 

[McPerth]

What are the political, social, economic, military, and technological consequences of all of this? What is going to be very different from the Traveller OTU?

Many things:

Whormhole dependent (you didn't gave us the details):

1. Depending on how much time it takes to travel through a wormhole, communications will be faster or slower than in Traveller (how long for a whormhole transit?)
2. Depending on how far the wormholes may take you, travel/communications fron one edge of the Imperium may be faster or slower than in OTU (do the wormholes take you to nearby systems or they can take you from Terra to Regina in one step?)
3. Whormholes may limit the size of your ships (do they limit máximum ship size? do they limit maximum number through it at once?)

As you see, insuficient data.

Strategically:

1. As enemy can only come by wormhole and those are near the sun, you only need to have fleet in the inward system, so less fleet can cover more space. And you only need to cover those whose far end is not inside your empire.
2. An attacking fleet is blind the first moments after crossing a wormhole, so the defenders (shuld they have pickets on the far side of it to warn) can wait for the blind enemy with thir guns ready
3. For the same reasons, piracy/smuggling/raiding will be quite more difficult, as you cannot count on the SDBs being on the far part of the system.

Commerce:

1. As the trading ships need to move from/to the wormholes ends, trade is slower (from planet to planet, across the empire it may even be faster, depending on the whormholes point 2
2. If the wormholes have a limit of tonnage, ships or both admited, they may become clogged among high trade systems, as there would need to be many ships (and with limited size) traveling through the same point

And this is only the tip of the iceberg that I could think about now. This changes would lead to universe quite different from OTU, though that does not mean less interesting and fun to play.

 

[Adam Dray]

Let's see. Taking questions and comments in order:

Coolant won't help as there is no place for the coolant to MOVE the heat to. (Coolant is a heat mover. There is no place in your set up to move the heat TO)

The coolant system is designed to keep certain parts of the ship from overheating and malfunctioning. You have one heat generator inside the ship (a nuclear reactor that splits atoms and releases huge amounts of energy, which produces heat) and another outside the ship (a star you're entering).

If the bubble were a truly closed system, then it wouldn't take on heat from outside, but it does. Very powerful nuclear energy can push through the bubble. Also, the bubble oscillates for sensor readings, and that's all energy the closed system is taking on.

Also, while the total energy inside a closed system cannot change, the concentration of heat can. This is why we cool nuclear reactors today. We need to keep certain parts of the ship from overheating so that parts (and people) don't malfunction. You do that by distributing heat to other parts of the ship, including the giant vacuum you're carrying around with you, between the metal hull and the bubble.

The heat of the reactors can be regulated even in the closed system. You're moving heat from the reactors to the water to ammonia coolant to the vacuum outside the ship via steam. Over time, the coolant forms a vapor cloud outside the ship, but inside the bubble.

Your ships would melt in a time increment measured in minutes or a VERY few hours, not days.

I don't see it. Are you saying that they hold too much heat because of the bubble? If so, then they stop and vent into space till heat is reasonable, then continue on their way.

It's only when you can't open the bubble that you have a mostly-closed system taking on heat.

I believe that the ISS has temperatures that reach +250F / +121C. That's pretty damned hot, and that's at 1 AU. For the sundiving to work, this has to accept that almost none of the solar radiation striking the outside of the bubble is able to penetrate to the inside. Still, every bit of heat it takes on is heat it has to deal with.

 

[Adam Dray]

Have you taken the idea from Starfighter or Imperial Starfighter?

The idea of warp points (or wormholes) and STL constant speed in system travel reminds me of it.

No, I made this stuff up myself. It's undoubtedly influenced by science fiction, my reading of modern science (non-fiction), and various RPGs I've encountered over decades.

I was very surprised to see similarities in Traveller and other fiction, though. My bubble is basically a black globe. My hackdrive is basically stutterwarp. My sungates are basically wormholes but are influenced by stuff like this. None of what I'm doing is completely novel, though my "hackdrive" idea might be original, as a physical concept.

What do Starfighter and Imperial Starfighter say?

 

[Adam Dray]

Many things:

Whormhole dependent (you didn't gave us the details):

1. Depending on how much time it takes to travel through a wormhole, communications will be faster or slower than in Traveller (how long for a whormhole transit?)
2. Depending on how far the wormholes may take you, travel/communications fron one edge of the Imperium may be faster or slower than in OTU (do the wormholes take you to nearby systems or they can take you from Terra to Regina in one step?)
3. Whormholes may limit the size of your ships (do they limit máximum ship size? do they limit máximum number through it at once?)

Wormhole travel is very fast: effectively instantaneous across interstellar distances. I suppose I could change that a little if I want to slow things down, but my intuition fights that. I want the jump itself to be a short trip.

Wormhole travel can take you anywhere, but Nova Roma didn't build them and it doesn't know how to build them, and they don't know who DID build them. It's probably a remnant of a very, very advanced race, as they seem to have seeded all of these systems with genetically-compatible life forms on Earth-like planets.

That is, wormholes tend to connect systems with Earth-like planets. You can't get to Barnard's Star or Alpha Centauri via wormhole, because there's apparently nothing of interest there.

Wormhole diameter is the limit, and as I said earlier, they're usually 1 km or so in size. Nova Roma's ships are tiny in comparison.


More later.

 

[HG_B]

Also, while the total energy inside a closed system cannot change, the concentration of heat can. This is why we cool nuclear reactors today. We need to keep certain parts of the ship from overheating so that parts (and people) don't malfunction. You do that by distributing heat to other parts of the ship, including the giant vacuum you're carrying around with you, between the metal hull and the bubble.

I understand what you are saying. It's fine for a total sci-fi game. No worries. I was just pointing out that there is no way without an extra dimensional heat sink, that it would work if someone looked at it too hard. No biggie to violate physics. I thought I'd just point out in case a player springs it on you in the future.

 

[McPerth]

No, I made this stuff up myself. It's undoubtedly influenced by science fiction, my reading of modern science (non-fiction), and various RPGs I've encountered over decades.

I was very surprised to see similarities in Traveller and other fiction, though. My bubble is basically a black globe. My hackdrive is basically stutterwarp. My sungates are basically wormholes but are influenced by stuff like this. None of what I'm doing is completely novel, though my "hackdrive" idea might be original, as a physical concept.

What do Starfighter and Imperial Starfighter say?

First of all, sorry, I meant Starfire, not Starfighter

Starfire is a game of spaceships combats, and Imperial Starfire its strategic adaptation. There, ships move through a force field that propels them as a reactionless drive, to speeds up to 10% c, and there are warp points dispersed along the system that lead you instantaneously to another system (sounds familiar to you).

The main difference with your system is that warp points are bidirectional, not always near the star and have a size limit.

The fact I played it years ago is one of the reasons I could so quickly to tell you the strategic differences that makes on defending systems.

And BTW, another strategic difference would be the use of mines. As the ships must travel from a specific point, minefields may be useful, while in OTU, with all the system to cover, they are useless or nearly so.

Wormhole diameter is the limit, and as I said earlier, they're usually 1 km or so in size. Nova Roma's ships are tiny in comparison.

I must have skiped it when first Reading your post, sorry. Never intended to criticise your post (after all, you present a quite interesting ATU), just to justify the vagueness of my own answers.

Every time you take a sensor reading, you must drop your protective bubble long enough to let in enough light and other radiation. This causes you to take on heat. The last 30 seconds of the journey are usually done completely blind, so you aim the ship as best you can and pray. The Sun can produce forces that tear through a ship's bubble, but intense damage is more common than disintegration.

That means that even if the whole empire fleet could fill into a wormhole, some spacing must be among ships to avoid collisions (more so as they go blind or with unreliable sensors at 0.1c), meaning that probably no more than 1-2 ships could go through it per minute (depending on flight control, etc...).

 

[Adam Dray]

Strategically:

1. As enemy can only come by wormhole and those are near the sun, you only need to have fleet in the inward system, so less fleet can cover more space. And you only need to cover those whose far end is not inside your empire.
2. An attacking fleet is blind the first moments after crossing a wormhole, so the defenders (shuld they have pickets on the far side of it to warn) can wait for the blind enemy with thir guns ready
3. For the same reasons, piracy/smuggling/raiding will be quite more difficult, as you cannot count on the SDBs being on the far part of the system.

Wow, I hadn't considered the military strategy of this. Wow. How do you even counteract this? Is it basically an Omaha Beach scenario every time you invade a starship-capable system that doesn't want you there?

I think piracy is something that happens between the star and its system, right? Space is big. If you're three days from a planet, there might not be any kind of lane cruiser within a day or two of you when the pirates hit you.

Of course, detection is probably much harder than in CT. As far as I can tell, CT assumes that detection is impossible to avoid at almost any distance within system. Wrap a black globe around your ship, and that changes.

Commerce:

1. As the trading ships need to move from/to the wormholes ends, trade is slower (from planet to planet, across the empire it may even be faster, depending on the whormholes point 2

1. 
   
   Communication
   Certainly star-to-star travel is faster and star-to-planet travel is slower. I would think that communication travel across the empire could be very fast. The traditional x-boat idea with a relay team of small, jump-ready ships gets you more here. Sit a ready x-boat just far enough from a star to avoid heat damage right before a scheduled delivery. When the x-boat pops out of the sungate, do a quick transfer of mail (electronic or physical), then the readied x-boat does a quick flight to the other sungate and jumps.
   
   Assume that sungates are distributed around the sphere of the star, not concentrated together. Assume that most of the stars that support Earth-like planets are not supergiants, but are Sun-sized. The Sun is 700,000 km, or 2.3 light-seconds, across, or about 7.3 light-seconds around, so a 0.1c hackdrive can circumnavigate the Sun in 73 seconds.
   
   That means you can get your mail and then hit the new sungate within minutes. If we're talking electronic messages only, beamed from boat to boat by laser or radio, then a message could travel across 20 systems in a couple hours.
   
   Due to the expense of these ships in this early-stellar TL universe, though, I don't think there's a dedicated x-boat network yet. They'd just dispatch Navy ships to move as fast as possible. Messages probably take 1-6 days per system (convenient range, that).
   
   

   1. If the wormholes have a limit of tonnage, ships or both admited, they may becom clogged among high trade systems, as there would neet to be many ships (and with limited size) traveling through the same point

   
   The wormholes are 1km across and uni-directional. Travel through them is instantaneous. There's no danger of collision, I think.
   
   The wormholes are really just folds in space from star to star. There's no real distance between them. They don't have a capacity, so any number of ships could enter at the same time, assuming they don't collide in real space. I think a sungate could be as busy as a modern airport runway.

 

[Adam Dray]

I understand what you are saying. It's fine for a total sci-fi game. No worries. I was just pointing out that there is no way without an extra dimensional heat sink, that it would work if someone looked at it too hard. No biggie to violate physics. I thought I'd just point out in case a player springs it on you in the future.

I love criticism. I'm just debating. I think I don't understand the science the same way as you and I want to clear it up. I have a basic physics background, but I'm a layman. If I can avoid breaking science, I will.

I realize that at some point, I have to cheat to get FTL. Where I've planned to cheat:

• Obviously, we don't (yet) know how to create a new bubble universe around a ship. It's theoretically possible. There's no theory about how to get out of that bubble, AFAIK.
• The hackdrive is purely fiction. I'm playing with some of the wild ideas out there that the universe is a computational simulation. As a professional software programmer, I am aware of rounding error. The hackdrive takes advantage of so-called rounding errors in conversion between relativistic space (presumably continuous / real numbers) and quantum space (which work as integers).
• The idea is that the hackdrive is inertialess and thus does not violate special relativity. Inside the bubble, the ship is not accelerating. The bubble itself is not actually moving. It is hacking the universe and skipping ahead, one fraction of an inch at a time. It is a loophole between special relativity and quantum mechanics. Woohoo! (Also, totally fiction.)

The rest I think is physically plausible.

Let's hash this out.

Why do you think there's a heat problem?

 

[Adam Dray]

First of all, sorry, I meant Starfire, not Starfighter

Starfire is a game of spaceships combats, and Imperial Starfire its strategic adaptation. There, ships move through a forcé field taht propels them as a reactionless drive, to speeds up to 10% c, and there are warp points dispersed along the system that lead you instantaneously to another system (sounds familiar to you).

It does sound familiar! I have never even heard of this game. It sounds like it might be something useful to simulate starship battles for my universe, though, with a couple mods! Thanks for the pointer.

That means that even if the whole empire fleet could fill into a wormhole, some spacing must be among ships to avoid collisions (more so as they go blind or with unreliable sensors at 0.1c), meaning that probably no more than 1-2 ships could go through it per minute (depending on flight control, etc...).

Yeah, I think they'd want to stagger them for safety.

At the same time, I think they'd want to get them through, as many as possible, quickly. This is the counter to the Omaha Beach scenario of having a blockade of starships or missile batteries waiting on the other side. It feels like the only reasonable way to invade a system is to rush a whole lot of ships through at once and overwhelm the defenses. The first ships through are probably unmanned decoys. Expensive, 200 MCr decoys. Ow.

 

[HG_B]

I realize that at some point, I have to cheat to get FTL. Where I've planned to cheat:

Let' take that up. IF you want FLT you have to cheat. BUT, if you want to simulate FLT (with jump for instance) you don't. We don't know if it is impossible or possible. So, you are on good ground so far with your proposal.

Why do you think there's a heat problem?

Too much ground to cover via a forum, about thermodynamics and radiation. In short, you can't store heat away in the way you propose in that type of closed system. It will reach an energy equilibrium fairly quickly. Too quickly to save your ship or crew.

So, you have two choices. 1) hand wave. 2) dump the heat energy outside that system. Via an extra dimensional opening if you want to remain closed off from real space.

 

[Adam Dray]

Too much ground to cover via a forum, about thermodynamics and radiation. In short, you can't store heat away in the way you propose in that type of closed system. It will reach an energy equilibrium fairly quickly. Too quickly to save your ship or crew.

So, you have two choices. 1) hand wave. 2) dump the heat energy outside that system. Via an extra dimensional opening if you want to remain closed off from real space.

And I'm proposing #2: dump heat out of the system by opening the bubble.

The cooling system is for the very short time that the system is within close proximity of a star, flying blind (can't open the bubble), straight into a sungate. Let's say that's 30 seconds total time, into the danger zone of star 1 and out of the danger zone of star 2.

Can a cooling system protect a starship for 30 seconds?

 

[HG_B]

And I'm proposing #2: dump heat out of the system by opening the bubble.

The cooling system is for the very short time that the system is within close proximity of a star, flying blind (can't open the bubble), straight into a sungate. Let's say that's 30 seconds total time, into the danger zone of star 1 and out of the danger zone of star 2.

Can a cooling system protect a starship for 30 seconds?

30 seconds is no trouble at all. You just use your normal cooling paradigm if that's all you need.

BTW, what is the normal space drive?

 

[Adam Dray]

30 seconds is no trouble at all. You just use your normal cooling paradigm if that's all you need.

BTW, what is the normal space drive?

The backup drive? Some kind of rocket, I'd guess. It's incredibly slow and for use in emergencies only (when the hack drive doesn't work), and the bubble has to be off for it, obviously.

If you mean, "how does a starship normally get from the Earth to the Sun?" that's via the hackdrive at 0.1c.

Assume the bubble has a very, very low solar absorptivity, since it's almost perfectly black (or light does weird things around it). It would absorb very little heat as it moved from Earth to Sun. However, it's also dropping the bubble for some fraction of the time: let's say 100 milliseconds every 2 seconds, so 5% of the time. That allows solar radiation (and very diffuse gas) to get in but also releases energy (perhaps via a laser heat pump).

 

[HG_B]

If you mean, "how does a starship normally get from the Earth to the Sun?" that's via the hackdrive at 0.1c.

3,000,000 KM/sec. Nice!

Assume the bubble has a very, very low solar absorptivity, since it's almost perfectly black (or light does weird things around it). It would absorb very little heat as it moved from Earth to Sun. However, it's also dropping the bubble for some fraction of the time: let's say 100 milliseconds every 2 seconds, so 5% of the time. That allows solar radiation (and very diffuse gas) to get in but also releases energy (perhaps via a laser heat pump).

Black means high absorption btw so stick with the curving space thing 5% opening time for a trip of more than say an hour would be problematic as laser heat pumps wouldn't work. But, as you said that it is only on for 30 seconds, you don't have to worry.