[Spaceships] Reactionless Drives, Pseudovelocity, and NOT breaking a setting (much)

[Ulzgoroth]

Originally Posted by vicky_molokh

On the contrary, it seems to break conservation of momentums because it 'just moves'. Like this:

Well, of angular momentum, yes, naturally.

[lwcamp]

Originally Posted by vicky_molokh

So, I want to a coherent stat-up of how reactionless drives (and, by necessity, pseudovelocity) work in a setting. I know they're TL^, and that means that the best I can hope for is to minimize the damage to the setting in the process. So far, setting-breaking consequences that I would like to avoid the most:

• Hypervelocity kinetic-kill applications. This pretty much necessitates invoking Pseudovelocity.

Then you probably want it to be a more or less slow pseudovelocity. Otherwise, you can play the following trick:

Suppose you can pseudospeed yourself to 0.01 c. Now go park yourself over a planet. Say, just above Earth's exosphere. Make sure you're not in orbit - stay stationary and hover over the planet with pseudospeed. Earth's gravity is pulling you down. It is exerting a force on you, and since by definition your change in momentum is force integrated over time, you are gaining momentum toward the center of the Earth. No problem, though - you can pseudospeed upward to counter your downward real velocity. Every second, you gain another 9.8 m/s of downward velocity. After about 85 hours of this, you have picked up nearly 0.01 c of real velocity. Beyond this point, your pseudovelocity drive is going to have trouble keeping up, so maneuver away from Earth. Of course, you conveniently positioned yourself so that the real velocity you built up helps you get to your real destination - say, it points towards the eeevil base of eeevilness on Callisto. So you zip over to Callisto with real and pseudo velocity, and then plow into your target at an actual speed of 0.01 c. Kaboomie!

So, probably best to keep the pseudospeed less than about 100 km/s or so.

Luke

[Ulzgoroth]

Originally Posted by lwcamp

Then you probably want it to be a more or less slow pseudovelocity. Otherwise, you can play the following trick:

Suppose you can pseudospeed yourself to 0.01 c. Now go park yourself over a planet. Say, just above Earth's exosphere. Make sure you're not in orbit - stay stationary and hover over the planet with pseudospeed. Earth's gravity is pulling you down. It is exerting a force on you, and since by definition your change in momentum is force integrated over time, you are gaining momentum toward the center of the Earth. No problem, though - you can pseudospeed upward to counter your downward real velocity. Every second, you gain another 9.8 m/s of downward velocity. After about 85 hours of this, you have picked up nearly 0.01 c of real velocity. Beyond this point, your pseudovelocity drive is going to have trouble keeping up, so maneuver away from Earth. Of course, you conveniently positioned yourself so that the real velocity you built up helps you get to your real destination - say, it points towards the eeevil base of eeevilness on Callisto. So you zip over to Callisto with real and pseudo velocity, and then plow into your target at an actual speed of 0.01 c. Kaboomie!

So, probably best to keep the pseudospeed less than about 100 km/s or so.

Luke

Or toss the momentum conservation and have pseudovelocity travel mess up your banked real velocity.

[malloyd]

Originally Posted by Ulzgoroth

Or toss the momentum conservation and have pseudovelocity travel mess up your banked real velocity.

Or prevent you from acquiring any - inertialessness could work, while your pseudovelocity drive is on, you have no mass, so there are no gravitational forces acting on you. But ultimately you aren't going to be able to close all the loopholes with a mathematical solution - reactionless motion violates conservation of energy somewhere *by definition* and once you have energy from nothing, there's some way to turn that into a hugely destructive weapon. Theoretically you might set it up so you always destroy energy, but I'm pretty sure if you do this the drive must consume more energy than a photon drive capable of moving the same mass the same distance in the same time, which makes it pretty useless.

It's really simplest to just declare it to work [however] for propulsion purposes and for all free energy or destructive exploits to simply fail regardless of how that contradicts the way it works for propulsion.

[Ulzgoroth]

Originally Posted by malloyd

Or prevent you from acquiring any - inertialessness could work, while your pseudovelocity drive is on, you have no mass, so there are no gravitational forces acting on you.

That wouldn't help, since you can just as easily (if a bit less efficiently) toggle the drive off to accumulate real speed and then back on to recover altitude.

Originally Posted by malloyd

But ultimately you aren't going to be able to close all the loopholes with a mathematical solution - reactionless motion violates conservation of energy somewhere *by definition*

I...do not think this is true. Can you show it?

Originally Posted by malloyd

and once you have energy from nothing, there's some way to turn that into a hugely destructive weapon.

I very much doubt that this is true. If you have lots of power in the form of uncapped kinetic energy from nothing, obviously you can probably do something messy with that.

But that's a pretty specific sub-case of energy from nothing.

[Johnny1A.2]

Originally Posted by Fred Brackin

Nah, not a construction brick that's much too small. Even if you run it up to near C inert on a precisely chosen intrinsic and then render it free all you've got is something that will blow up as soon as it hits atmosphere.

After several shenanigans involving undetectable speedsters everyone is running a massive overlap on their electros and either free you'll see the mini-bergenholm on the brick detected or the naked brick at near c will be detected by the ionization as it flies through interplanetary medium of normal density.

That's not how you'd do it. With the Bergenholm, what you'd do is take a brick or a rock or a ball of cotton, put on a ship, and let that ship accelerate inert until it's pressing against c, relative to Prime Base. That wouldn't be hard for ships like those of the later Lensman books. It doesn't matter if it takes a week to do it.

Then, when you've got a velocity of .99c or .999c relative to Prime Base, then you turn on the Bergenholm. Now you transport the thing to Prime Base, making very sure to keep it constantly inertialess. You take it to Earth and sneak it near whatever your target is.

Then you turn off the Bergenholm, either with a timer, a remote, or a suicide bomber, and watch the film of the multi-megaton fireball on the evening news.

Note that this technique can be used on any scale. Any given 'free' cargo could actually have a megadisaster intrinsic velocity, there's nothing to indicate this until you turn off the Bergenholm. You could weaponize any shipment of anything that way.

Granted active Bergenholms are themselves detectable by sensors, but all that tells you is that there's an active Bergenholm. That's not even unusual on most Civilized worlds, especially near military facilities and space ports. Spacecraft usually inert in space, but they use Bergenholm-equipped space armor, etc, all the time on the ground. Nor is it improbable that an active Bergenholm could be shielded from sensors anyway.

[dataweaver]

Hmm… gravitational acceleration can be defined as the gradient of the potential energy field. With or without pseudovelocity, a ship will have to navigate the potential energy field; and that can result in the ship's real velocity changing in response to the gravity fields. For instance, a ship that engages its PV drive to go 180˚ around the sun will find when the PV drive is deactivated that its real velocity will have rotated 180˚ as well. Likewise, dropping down the gravity well will result in potential energy converting into real kinetic energy, and your overall speed will have increased as if you had fallen down the well rather than pseudo-flying down it.

How would that affect things?

[vicky_molokh]

Originally Posted by lwcamp

Then you probably want it to be a more or less slow pseudovelocity. Otherwise, you can play the following trick:

Suppose you can pseudospeed yourself to 0.01 c. Now go park yourself over a planet. Say, just above Earth's exosphere. Make sure you're not in orbit - stay stationary and hover over the planet with pseudospeed. Earth's gravity is pulling you down. It is exerting a force on you, and since by definition your change in momentum is force integrated over time, you are gaining momentum toward the center of the Earth. No problem, though - you can pseudospeed upward to counter your downward real velocity. Every second, you gain another 9.8 m/s of downward velocity. After about 85 hours of this, you have picked up nearly 0.01 c of real velocity. Beyond this point, your pseudovelocity drive is going to have trouble keeping up, so maneuver away from Earth. Of course, you conveniently positioned yourself so that the real velocity you built up helps you get to your real destination - say, it points towards the eeevil base of eeevilness on Callisto. So you zip over to Callisto with real and pseudo velocity, and then plow into your target at an actual speed of 0.01 c. Kaboomie!

So, probably best to keep the pseudospeed less than about 100 km/s or so.

Luke

Yeah, that's something I've considered. 100km/s is slightly under three weeks per astronomical unit, so should be okayish for in-system travel.

But the other idea I had is some sort of 'bleed over' effect, such that when one pushes away from a gravitational well, some of the work the drive performs behaves as if the drive is 'pushing' against the planet, thus spending energy on reducing/compensating real downward velocity. Sort of like the Spooky Traction At A Distance Drive. Of course, this still leaves the ability to theoretically get real velocity by matching with a big celestial body on a fast orbit elsewhere, but that seems highly impractical. Also, maybe some sort of bleed-over that makes real velocity gradually match that of a close big body while the drive is active (again, not a panacea). Are these two bleed-overs useful / subtly harmful / what else can be said about these two ideas?



Also, what are the consequences of the ability to break conservation of angular momentum with TL^ drives?

[(E)]

Slightly off the current direction of the thread but here is another alternative drive. I hope it's understandable.
Quantum brick drive
Aka
- fast talk propulsion
- suggestion drive
- quantum sphere drive

The theory
Quantum teleporting works by "telling" matter it is somewhere else. Working from that idea you can "tell" matter other things to. What about telling matter it has different momentum.

Take a large dense sphere of (superscience) metal. Apply a "suggestion field" to the metal sphere. This field alters the quantum state of the sphere to make it's momentum "suggestable"

When the sphere is "suggestable" it's momentum alters to match the momentum of near by matter. The nearest planet for example. With the sphere's momentum tied to the planet's momentum at 100% efficiency it will be as hard to shift the sphere as it is to shift the planet.

Now say you can artificially tell the sphere to have a different momentum. But you can't do this very well the best you might be able to achieve is say 0.1% success. This is the heart of the reactionless drive. The sphere resides within the drive chamber and "pushes" the ship.

The quantum sphere drive tells one component (the "sphere") to move at a certain speed and direction. Taking the rest of the ship with it. When close to a large object the large object will also influence the speed and direction of the "sphere" to match the large object.

- The drive does not provide acceleration
- The drive will automatically slow to match the momentum of large objects
- the drive will match galactic spin
- you can set what the maximum momentum is.
- if momentum is changed too fast the sphere will break the drive chamber.
- the suggestion field does not turn off and on instantly it takes time to come into effect and it takes time to stop working.
- any time the suggestion field is working you can tell it a new momentum.

[Ulzgoroth]

Originally Posted by Johnny1A.2

That's not how you'd do it. With the Bergenholm, what you'd do is take a brick or a rock or a ball of cotton, put on a ship, and let that ship accelerate inert until it's pressing against c, relative to Prime Base. That wouldn't be hard for ships like those of the later Lensman books. It doesn't matter if it takes a week to do it.

Then, when you've got a velocity of .99c or .999c relative to Prime Base, then you turn on the Bergenholm. Now you transport the thing to Prime Base, making very sure to keep it constantly inertialess. You take it to Earth and sneak it near whatever your target is.

Then you turn off the Bergenholm, either with a timer, a remote, or a suicide bomber, and watch the film of the multi-megaton fireball on the evening news.

Not sure that the use of the inertialess capability is contributing much to the relativistic bombardment problem. The ability to drive a payload to near-c speeds without using the Bergenholm is the foundation of what you're doing...