Comic Genesis Forums

allan_ecker wrote:So here's your UH2 for today via imageshack.

http://img254.imageshack.us/img254/6663/20070524gm7.png

GreatLimmick wrote: "Pegasus top"? I'm guessing that would be some application of the antigravity technology developed by Dr. Pegasus. One wonders just how much power that would consume, though...

As for the gravity plates... Another application of Pegasus-brand levitation tech? (That is, if you turn an antigravity generator upside down, do you get a gravity generator?)

Saundra wrote:To put it simply, YES.

More precisely, a Pegasus Top may be thought of as a ring which generates a sort of gravitational "wind" that pushes along the spin axis. If you were to have one of the round, flat disclike Pegasus Tops used in gravity plating in your hands, you'd feel one side push your hand away, as though you were holding two like-poled magnets, with the other pulling you like two opposite-poled magnets. You'd also notice that it resists rotating like any other gyroscope. (However, a strong Pegasus Top's gravity vector will override this pretty readily.)

If you then laid it on the ground, it'd tend to flip over (just like a magnet) and stick "suck side" down, creating an area of low-g immediately over it. Put four of them at the corners of a plank and, well, you've got a hoverboard. (The hoverboard WILL have a tendancy to flip over and stick if you don't keep the weight on it balanced properly, making many of the tricks in conventional skateboarding extremely difficult if not impossible.)

However, anyone trying to make thought-experiment perpetual motion machines from these is not going to have a lot of luck. There are two good reasons for this. One: Any time you use a Pegasus Top to lift anything, the kinetic and potential energy come directly out of the power supply. As the gravitational acceleration g sub P increases, so does the energy needed to maintain the field. (Doctor Pegasus was brilliantly careful outlining this in her paper On Descretized Magnetogravitation, and even then a lot of reviewers didn't grasp this subtlety and simply wrote it off.) Two: Pegasus Tops are still tops, and friction is still sucking energy out of that little bugger like nobody's business. A primary area of research concerning gravitronics is actually high-performance lubricants!

So in answer to your first question, there are a number of (dizzyingly complex) physical limitations to the size and implementation of Pegasus Tops, making most current models especially BAD at long range, high payload lifting. However, a Pegasus Plank launched from a light plane like SpaceShip One can carry enough fuel to get itself into orbit pretty handily, a feat even SpaceShip One couldn't manage. For this reason, Gravitronics have all but replaced conventional rocketry for getting into space, but they haven't brought about the sort of catastrophic revolution in space flight you'd get if, for instance, someone were to build a skyhook.

For example.

Saundra wrote:To put it simply, YES.

More precisely, a Pegasus Top may be thought of as a ring which generates a sort of gravitational "wind" that pushes along the spin axis. If you were to have one of the round, flat disclike Pegasus Tops used in gravity plating in your hands, you'd feel one side push your hand away, as though you were holding two like-poled magnets, with the other pulling you like two opposite-poled magnets. You'd also notice that it resists rotating like any other gyroscope. (However, a strong Pegasus Top's gravity vector will override this pretty readily.)

If you then laid it on the ground, it'd tend to flip over (just like a magnet) and stick "suck side" down, creating an area of low-g immediately over it. Put four of them at the corners of a plank and, well, you've got a hoverboard. (The hoverboard WILL have a tendancy to flip over and stick if you don't keep the weight on it balanced properly, making many of the tricks in conventional skateboarding extremely difficult if not impossible.)

However, anyone trying to make thought-experiment perpetual motion machines from these is not going to have a lot of luck. There are two good reasons for this. One: Any time you use a Pegasus Top to lift anything, the kinetic and potential energy come directly out of the power supply. As the gravitational acceleration g sub P increases, so does the energy needed to maintain the field. (Doctor Pegasus was brilliantly careful outlining this in her paper On Descretized Magnetogravitation, and even then a lot of reviewers didn't grasp this subtlety and simply wrote it off.) Two: Pegasus Tops are still tops, and friction is still sucking energy out of that little bugger like nobody's business. A primary area of research concerning gravitronics is actually high-performance lubricants!

So in answer to your first question, there are a number of (dizzyingly complex) physical limitations to the size and implementation of Pegasus Tops, making most current models especially BAD at long range, high payload lifting. However, a Pegasus Plank launched from a light plane like SpaceShip One can carry enough fuel to get itself into orbit pretty handily, a feat even SpaceShip One couldn't manage. For this reason, Gravitronics have all but replaced conventional rocketry for getting into space, but they haven't brought about the sort of catastrophic revolution in space flight you'd get if, for instance, someone were to build a skyhook.

For example.

Saundra wrote:However, anyone trying to make thought-experiment perpetual motion machines from these is not going to have a lot of luck. There are two good reasons for this. One: Any time you use a Pegasus Top to lift anything, the kinetic and potential energy come directly out of the power supply. As the gravitational acceleration g sub P increases, so does the energy needed to maintain the field. (Doctor Pegasus was brilliantly careful outlining this in her paper On Descretized Magnetogravitation, and even then a lot of reviewers didn't grasp this subtlety and simply wrote it off.) Two: Pegasus Tops are still tops, and friction is still sucking energy out of that little bugger like nobody's business. A primary area of research concerning gravitronics is actually high-performance lubricants!

GreatLimmick wrote: I'm surprised anyone needed it spelled out that the device isn't a perpetual motion machine, particularly if it includes a power supply in the first place. Messing with gravity is one thing; messing with thermodynamics is another thing entirely.

Saundra wrote: It's really easy to picture a sort of "infinite paddlewheel" with this mysterious, universally repulsive force, and when Peggy's first version of the paper came out, nobody'd even considered the possibility of "low energy" gravitronics, that is, gravitronic lifters not requiring stellar core masses moving at relativistic velocities. As a result, a lot of researchers had the whole concept of gravitronics neatly packaged away in the "stuff that's predicted but wouldn't actually work" category.

Peggy's claim that gravitronics could be operated at several orders of magnitude lower energies than previously suspected was akin in their eyes to saying that, given a sip of some potion she'd concocted, a child could juggle Volkswagons.

Of course to add to the irony of that statement, Dr. Lyse would prove just that a mere fifteen years later, although some would argue that once nanofibrous carbon, hyperenergetic compounds and nanotechnology get involved it isn't any child doing the juggling...

GreatLimmick wrote:I must say, however, that I am pleased to have received a reply from Saundra herself. I was expecting to be nothing more than a kickboard for boardie speculation.

Saundra wrote:Well, I am the resident gravitronics professor. Peggy could answer but she says I have a "more readible" way of explaining things.

GreatLimmick wrote:Hmm... If the top has to spin in order to function, would reversing the direction of spin also reverse the direction of the gravitational "wind"? Or is the mechanism more complicated than that?

Saundra wrote:Once again, there's a fairly intuitive aspect of gravitronics: the spin follows the good old right-hand rule. Things generally don't get "ugly" until you start trying to build devices which don't try to flip over, or which can nimbly dart about in the air like Sissy and Eliza's gravitronic lifters.

Even more complicated is the opening and control of the Kip Thorne wormholes you've seen all over UH2, from Sissy's "Spacetime Lenslets" to the various space and time portals used by various cast members. It had been correctly shown that, in conventional magnetogravity, there was no way to pry open a wormhole because the energy (and thus, mass) needed to generate the field was large enough to close the wormhole right back up again. This isn't the case with low-energy gravitronics, but a number of extremely delecate balancing acts (requiring computations that would send even especially bright graduate students scurrying under available furniture) must be carried out to correctly "thread the needle" of an existing subatomic singularity and "inflate" it to a useable size.

As we have seen, a number of extremely troubling technologies may be derived from this sudden discovery of (relatively) inexpensive, controllable wormholes.

The_Fox wrote: First, I am a little surprised that Moire's rotating space station was never attempted before, since that would seem the easiest way to get pseudo gravity into a single point in space. While we of this world and century have no idea how to get gravitics working (to my knowledge, but I'm not a physicist, I'm a technician), we could probably build a rotating grav-deck, if getting the stuff into space didn't make it so gosh darned difficult to build in there in the first place.

Moiré Dziva wrote:Oh, it's been tried before, and successfully. Just not on this scale. The ISS has both gravity plating AND a small rotating area which predates the plating. The Pegasus-generated artificial gravity is just vastly more convenient in a smaller station.

The_Fox wrote:Second, I've heard that the delicate mechanisms required of such rotating grav decks don't react well to outside thrust. Gravity pushing the person down towards the deck, but also towards on of the "walls" tends to do that, to say nothing of the delicate motors in the middle. In the UH-verse, would it still be necessary to generate gravity on moving ships with thrust, relying on rotating grav decks when stopped? (Thus requiring few grav decks that cannot be used in motion, and entire areas of the ship which require magnetic boots when stopped.) Or, could Dr. Pegasus's gravitonics help create a ship which can provide ambient gravity whether expending thrust or merely sitting and studying something?

Saundra wrote:Gravitronics generally could be used to provide consistent gravity plating; the real difficulty with gravity plating is getting it to perform certain levels of work. Above a certain number of watts output they start getting much less efficient. When the ship is under accelerations, of course, the amount of work needed to "cancel out" the thrust (like the Inertial Dampers on Star Trek) goes up, and eventually it becomes near-impossible to build a system robust enough.

Saundra wrote: A primary area of research concerning gravitronics is actually high-performance lubricants!

DetailBear wrote:

Saundra wrote: A primary area of research concerning gravitronics is actually high-performance lubricants!

I'm glad Rick and Jake could help.

Saundra wrote:Gravitronics generally could be used to provide consistent gravity plating; the real difficulty with gravity plating is getting it to perform certain levels of work. Above a certain number of watts output they start getting much less efficient. When the ship is under accelerations, of course, the amount of work needed to "cancel out" the thrust (like the Inertial Dampers on Star Trek) goes up, and eventually it becomes near-impossible to build a system robust enough.