Relativity and the Cultureverse

[Gullible Jones]

In Consider Phlebas, it's noteworthy that antigravity devices work on planetary surfaces, but not on orbitals, where centrifugal force simulates gravity. Am I therefore correct in assuming that general relativity is not obeyed in the Culterverse, in the Skein as well as in hyperspace? I'm pretty sure that IRL centrifugal force and gravity should be indistinguishable to a mass (or to a negative mass, if such can actually exist).

[Admiral Valdemar]

Why? You need the mass to exist for this anti-gravity to work against. No gravity well = no effect. Aside from anti-gravity being as technically impossible as FTL, the basic premise is sound. Unless the orbital has the mass of a planet at any one point, in which case it doesn't need top rotate.

[Gullible Jones]

I was under the impression that, from a rotating frame of reference, centrifugal force will "look" like a gravity well. I'll try to come up with an example...

Say that you're in a car, moving around a circular track at high speed. Centrifugal force pushes you outward, away from the center of the circle. However, a balloon or other buoyant object floating in the car will drift inward, towards the center of the circle.

Shouldn't an object with negative mass behave in the same way?

[Admiral Valdemar]

I was under the impression that, from a rotating frame of reference, centrifugal force will "look" like a gravity well. I'll try to come up with an example...

Say that you're in a car, moving around a circular track at high speed. Centrifugal force pushes you outward, away from the center of the circle. However, a balloon or other buoyant object floating in the car will drift inward, towards the center of the circle.

Shouldn't an object with negative mass behave in the same way?

That's simply the atmosphere's effect. Rotate a ring in vacuum with a balloon in the middle. Watch it do nothing. You see this to an extent in Red Planet when the ship's rotation sections come back online again.

[Gullible Jones]

I know... What I mean is, shouldn't a negative mass in a vacuum act like a buoyant object in an atmosphere? Or am I just being really dense?

[Admiral Valdemar]

I'm unsure where the negative mass comes in. I thought we were just talking about fields that work against gravity being exempt from working on Os?

[Gullible Jones]

Eh, forget the negative mass bit then... I'm just saying, wouldn't the centrifugal force effectively constitute a gravitational field within the frame of reference of the orbital's surface, under general relativity? Or do I have that wrong?

[TheLostVikings]

Eh, forget the negative mass bit then... I'm just saying, wouldn't the centrifugal force effectively constitute a gravitational field within the frame of reference of the orbital's surface, under general relativity? Or do I have that wrong?

On earth the water from a shower head falls straight down, in something that rotates to simulate gravity the water would curve slightly away from the direction of rotation. The effects aren't even similar on the macroscopic level.

[Ender]

Why? You need the mass to exist for this anti-gravity to work against. No gravity well = no effect. Aside from anti-gravity being as technically impossible as FTL, the basic premise is sound. Unless the orbital has the mass of a planet at any one point, in which case it doesn't need top rotate.

Depending on its operation, anti-gravity is a fully plausible technology. Consider a device that emits a stream of low interactivity particles that engage in defection rather than absorption with the collisions being highly elastic and triggering few if any scattering events. It would work like a pumped up photon drive, with the thrust propelling it up, the particle bouncing off the ground and coming up to impart more momentum back to the emitter, and repeat until it is to diffuse. It would follow being proportional to 1/r^4 (or more depending on what the author dictated the deflection angles to be) and could allow a low power draw to suspend the device for an indefinite time. It would require hand waving to create these magic particles, but it doesn't break any fundamental laws like FTL does.

[Admiral Valdemar]

Depending on its operation, anti-gravity is a fully plausible technology. Consider a device that emits a stream of low interactivity particles that engage in defection rather than absorption with the collisions being highly elastic and triggering few if any scattering events. It would work like a pumped up photon drive, with the thrust propelling it up, the particle bouncing off the ground and coming up to impart more momentum back to the emitter, and repeat until it is to diffuse. It would follow being proportional to 1/r^4 (or more depending on what the author dictated the deflection angles to be) and could allow a low power draw to suspend the device for an indefinite time. It would require hand waving to create these magic particles, but it doesn't break any fundamental laws like FTL does.

You mean like a Harrier? That's no more anti-gravity than anything I can see now. My R/C helo is "anti-gravity", then, as is a maglev train. The traditional form of AG technology is something that negates the effect of gravity, or pushes against gravity wells. There is no thrust or propellant.

[Starglider]

Culture anti-gravity seems to be misnamed; it seems to works more like SW repulsors (as Ender described), generating a counterforce rather than canceling out gravitic attraction. Actually this is pretty much implied by the fact that Culture AG can be used to accelerate an object upwards and laterally, as well as just making it float.

[Pinjar]

Given that Horzas Idriran suit was marvellous by comparison to the other Kraiklyn's Free Company suits and that The Culture was technologically superior to the Idriran. Can we actually say that the anti-gravity suits the free company use are Culture technology? Wasn’t most of their gear a mash of scraped together odds and ends? Most of which even the engineer of the free company didn’t understand.

If so then might it make sense that “anti-gravity” in the Culture novels might actually work on a Culture orbital but the lower technology species and societies the free company acquired their anti-gravity from wouldn’t expect it to have to work on an orbital.

Therefore the suits could be pre-configured for a planet and when they experience an orbital they just fatal error. Perhaps, somewhat perversely given what happens to Lenipobra on the mega ship, as a safety measure to stop users from flying straight into a wall … they stop but the orbital keeps moving…messy.

Kraiklyn does say it won’t work and why

Anti-gravity works against mass, not spin, so you’d end up taking an unexpected bath if you jumped over the side expecting to fly round to the bows.

but maybe he doesn’t actually know why and just doesn’t want any of them trying it. He is a mercenary and card shark rather than a scientist.

All speculation of course. In truth this part of the book hurt my head. I had to put it down and come back the next day.

[fusion]

Given that Horzas Idriran suit was marvellous by comparison to the other Kraiklyn's Free Company suits and that The Culture was technologically superior to the Idriran. Can we actually say that the anti-gravity suits the free company use are Culture technology? Wasn’t most of their gear a mash of scraped together odds and ends? Most of which even the engineer of the free company didn’t understand.

If so then might it make sense that “anti-gravity” in the Culture novels might actually work on a Culture orbital but the lower technology species and societies the free company acquired their anti-gravity from wouldn’t expect it to have to work on an orbital.

Therefore the suits could be pre-configured for a planet and when they experience an orbital they just fatal error. Perhaps, somewhat perversely given what happens to Lenipobra on the mega ship, as a safety measure to stop users from flying straight into a wall … they stop but the orbital keeps moving…messy.

Kraiklyn does say it won’t work and why

Anti-gravity works against mass, not spin, so you’d end up taking an unexpected bath if you jumped over the side expecting to fly round to the bows.

but maybe he doesn’t actually know why and just doesn’t want any of them trying it. He is a mercenary and card shark rather than a scientist.

All speculation of course. In truth this part of the book hurt my head. I had to put it down and come back the next day.

Personally I think that the antigrav on the cheap suits were "just" antigrav while the antigrav tech of the culture is some sort of field tech. After all the drones don't fall down in an orbital...

Also all the antigrav tech in the culture can accelerate an object upwards or else how did the company fly upwards in the attack against temple of light.

[Starglider]

Personally I think that the antigrav on the cheap suits were "just" antigrav while the antigrav tech of the culture is some sort of field tech. After all the drones don't fall down in an orbital...

Culture drones use some kind of general reactionless drive. They're capable of manuevering in small ships and deep space (seen in 'Excession'), without the need for matter or gravity to 'push off' or any apparent reaction thrust.

Also all the antigrav tech in the culture can accelerate an object upwards or else how did the company fly upwards in the attack against temple of light.

Sorry, by 'Culture AG' I meant 'Cultureverse AG'.

[Pinjar]

There seem to be quite a lot of different types of anti-gravity in science fiction and I think we end up calling them all anti-gravity for much the same reason we call an automobile an automobile whether it has hamsters or turbines under the bonnet. The effect is the same.

I believe I am right in saying that none of them really get past the fact pointed out in the OP that generally (no pun intended) you shouldn't be able to tell acceleration from acceleration due to gravity. Therefore any true anti-gravity must counter all acceleration felt by those that would, subsequent to its activation, find themselves in its area of effect. Thus it must be some quirk of or configuration of the technology (baring lots of techno-babble) that allows it to work as it seems to.

To elaborate: The way in which I glossed over this was to say to myself that on a planet for you to go up from ground and stay above your launch point you have to have the anti-gravity moving its area of effect so that it falls on a curve towards the planet. On the inside of an orbital a similar curve or even just staying still (so to speak) would mean that you hit the orbital because it is always coming towards you. The anti-gravity suit builders, for reasons of cost, expediency or pure practicality as they didn't need their suits to work on an orbital, built this correction into the suits either physically or in the control mechanisms and the free company just didn't know enough about the technology to make it work on an orbital.

It does still disturb me as to what exactly I would then mean by staying still as this implies some special frame of reference. Can anybody help me?

[Gullible Jones]

Well, there is the Grid... That's what Culture warp drives push off of, it seems to act as an absolute frame of reference (more or less).

[Pinjar]

Well, there is the Grid... That's what Culture warp drives push off of, it seems to act as an absolute frame of reference (more or less).

If we accept that at face value then I believe you have answered your original question.

If we can distinguish between a uniform gravitational field at a particular location and a uniformly accelerated reference frame, and an absolute frame of reference against which to judge them means that we can, then there is a real distinction between the two and we can not then have the most beautiful physical theory ever invented.

I am more than willing to be corrected on the wording because every-thing I have said has been marshmallow science (squeeze it into any shape and it still tastes nice but it is just empty calories), deliberately so of course as I was trying to make a marshmallow sculpture that would let me enjoy the book. I fear however that the marshmallow sculpture is made of soap but as I like the story I will eat it anyway.

Of course if I am allowed to use techno babble…

[techno-babble]
A photon has a perpendicular temporal dimension. That is to say that although from our point of view it seems that it would make sense that from the photons point of view its point of view should have no temporal dimension actually from the photons point of view we would have no temporal dimension.

This perpendicular dimension is different for each photon so there is no absolute frame of reference and the antigravity device then splays (lays out flat and stretches and pins the parts it needs) the photon to surround it and as any acceleration involves the changing of energies no gravity is experienced inside the area of effect as there is no time for these changes to occur.

To complete the techno-babble version of my marshmallow sculpture I view the FTL as a closed gravity loop. That is to say that only your portion of the journey seems to be faster than light you actually have a shadow that travels back to your time and space of departure when you arrive at your destination. A faster or more powerful warp drive just makes your shadow larger and your part of the loop smaller. So no causality violation is possible.
[/techno-babble]

Unfortunately the techno-babble marshmallow sculpture is made of marble and breaks my teeth.

[Mayabird]

Kraiklyn was a bungling idiot, but he was right about their anti-grav, or at least its effects, considering that one kid who tried to use it on the orbital and plunged to his death.