Artificial Gravity questions (again)

[McPerth]

Taken from another thread:

Nonetheless, ITTR another (also MT) article talking about using the gravity as anti-hijack tool by reversing and returning in the specific zone the hijackers were...

As for gravity plates and such...

What if the hijackers / pirates have grav belts or such on? An automatic sensing system on something like that counteracts whatever the crew is doing and renders that effort useless.

That made me think about it and I came to a question:

Would grav belts (or vehicles, for what's worth) work well in an artificial gravity field? After all, that would mean two artificial gravity fieds interacting with each other, and results are not always the expected in those situations...

 

[AnotherDilbert]

Would grav belts (or vehicles, for what's worth) work well in an artificial gravity field? After all, that would mean two artificial gravity fieds interacting with each other, and results are not always the expected in those situations...

Anti-gravity is not the same as artificial gravity.

I don't think we any glimmer of a canonical answer, so you can safely use any interpretation you wish?

 

[aramis]

Anti-gravity is not the same as artificial gravity.

Quite true. In TNE & T4, Contragravity simply cuts one off from local gravity via a field effect with about 98% efficiency.

Artificial Gravity is very localized, and cannot propel a ship directly.

Gravitic Thrusters (in T4) are a different breakthrough based upon the same theories as AG and CG, but working differently.

I don't think we any glimmer of a canonical answer, so you can safely use any interpretation you wish?

There was a canonical statement somewhere in T4, but I can't for the life of me remember where in T4. I don't recall which way, only that someone was citing it.

 

[AnotherDilbert]

There was a canonical statement somewhere in T4, but I can't for the life of me remember where in T4. I don't recall which way, only that someone was citing it.

I'm glad I was wrong, let's hope someone remembers where it is.

 

[baktegon]

The T4 book states this about Anti-Grav belts on page 67.

Grav Belt
A standard model TL12 grav belt looks something like a parachute harness with a "stiffener" that runs down the back, a series of artificial gravity modules around the waist, and a set of low-energy thrusters for lateral motion. A grav belt masses about 20 kg, including its integral fusion plant, but once it is turned on, a neutral control setting eliminates this weight (though not its inertia)....A grav belt user can accelerate at about 0.5 G in standard 1 G gravity, which is enough to cover six outdoor bands from a standing start in one combat round. Top speed is about 200 kph, or 20 outdoor bands per round.

To me that says if gravity is present, the belt can accelerate. I didn't see anything about Grav Belts in artificial gravity specifically but I haven't read T4 cover to cover.

 

[McPerth]

Anti-gravity is not the same as artificial gravity.

True, but both interfere with gravitons, and interfering twice with the same target does not always give the intended results...

I'm not sure I can explain myself well in this matter, as I treat gravitics more as a matter of "canon says they work. Period." than really understanding the principles behind them (yes, I just handwave them).

Let's see 3 diferent situations, and how I'd treat them:

1. natural graviton producing field (e.g. a planet): as there are gravitons, grav plates work.
2. simulated gravity (e.g. "hamster cage" ship, as the Lab Ship was told to work in CT, IIRC): there are no gravitons, just acceleration, so, grav plates don't work.
3. artificial gravity: I guess there are gravitons, but are "artificial" ones, without the grav well usually induced by them. Not sure about the result.

As I see grav plates, they don't just nullify gravity (TNE/T4 may be different, see below), but "push" against the gravity well, and while artificial gravity produces gravitons (I guess) there's no gravity well. It would be as treating to float over rain (after all, rain is water, and if you can float in water... :CoW

Quite true. In TNE & T4, Contragravity simply cuts one off from local gravity via a field effect with about 98% efficiency.

Then a 100 kg body with contragrav will still weight 2 kg...

Grav Belt
A standard model TL12 grav belt looks something like a parachute harness with a "stiffener" that runs down the back, a series of artificial gravity modules around the waist, and a set of low-energy thrusters for lateral motion. A grav belt masses about 20 kg, including its integral fusion plant, but once it is turned on, a neutral control setting eliminates this weight (though not its inertia)....A grav belt user can accelerate at about 0.5 G in standard 1 G gravity, which is enough to cover six outdoor bands from a standing start in one combat round. Top speed is about 200 kph, or 20 outdoor bands per round.

And where does this acceleration comes if you still weight 2% of your mass? If there's atmosphere, off course, buoyancy will do it, but in a vacuum environ, you just would be able to make higher or longer jumps, but not to fly, as Grav vehicles do :CoW:.

 

[Enoki]

Well, there's always going to be some "natural" gravity present when you have mass. Starship = mass therefore it has gravity, however weak. Potentially, the artificial gravity system is simply an amplifier, and in more sophisticated systems is directional (eg., can compensate for inertia too). The system simply amplifies the existing natural gravity present and because it has some directionality, the result is either more or less gravity than is present naturally.

A grav belt would have to have both systems present, one to allow the gravity of the wearer to be neutralized and another to provide inertia for movement. A simpler version might just shift the gravity present of the wearer without providing inertia for movement.

So, I'd think the result would be where two or more independent systems of gravity are present they'd work the way two or more natural systems of gravity do in physics.

 

[McPerth]

Well, there's always going to be some "natural" gravity present when you have mass. Starship = mass therefore it has gravity, however weak. Potentially, the artificial gravity system is simply an amplifier, and in more sophisticated systems is directional (eg., can compensate for inertia too). The system simply amplifies the existing natural gravity present and because it has some directionality, the result is either more or less gravity than is present naturally.

But in this case, if you are inside the ship, the "natural" gravity well (however micro) that the ship produces does not come from a specific direction, but all arround you. So, any amplifier will "push" all arround you, not in a specific direction (again, I'm not sure I can explain myself well, I hope you can understand what I mean).

And, assuming the grav belt works in a ship's artificial gravity, what would happen if someone manipulates it, changing the grav polarity in quick succession (as would an anti-hijack program do)?

 

[Condottiere]

Bring along your own portable black hole.

Gravitational motors need something significant to grip into and push.

 

[AnotherDilbert]

Let's see 3 diferent situations, and how I'd treat them:

1. natural graviton producing field (e.g. a planet): as there are gravitons, grav plates work.
2. simulated gravity (e.g. "hamster cage" ship, as the Lab Ship was told to work in CT, IIRC): there are no gravitons, just acceleration, so, grav plates don't work.
3. artificial gravity: I guess there are gravitons, but are "artificial" ones, without the grav well usually induced by them. Not sure about the result.

Sounds reasonable, but apparently T4 has a description of how this works.

As I see grav plates, they don't just nullify gravity (TNE/T4 may be different, see below), but "push" against the gravity well, and while artificial gravity produces gravitons (I guess) there's no gravity well. It would be as treating to float over rain (after all, rain is water, and if you can float in water... :CoW

That is CT, MT Anti-grav, not TNE, T4 Contra-grav.

And where does this acceleration comes if you still weight 2% of your mass? If there's atmosphere, off course, buoyancy will do it, but in a vacuum environ, you just would be able to make higher or longer jumps, but not to fly, as Grav vehicles do :CoW:.

I'm not familiar with T4 or T5, but TNE also uses Contra-Grav: It cannot produce thrust, you also need a conventional thruster to move forward. This is for all contra-grav applications, like air/rafts, grav tanks, and grav belts.

 

[whulorigan]

1. simulated gravity (e.g. "hamster cage" ship, as the Lab Ship was told to work in CT, IIRC): there are no gravitons, just acceleration, so, grav plates don't work.

It is interesting to speculate if this would be so. In General Relativity, an accelerated reference frame and a gravitational field are considered equivalent and indistinguishable. A Unified Theory of "Quantum Gravity" might require the generation of gravitons as a consequence of accelerations. Since we do not have such a theory, one can only speculate.

1. artificial gravity: I guess there are gravitons, but are "artificial" ones, without the grav well usually induced by them. Not sure about the result.

An interesting possibility might be what are a consequence of some of the current Unified Field Theory candidiates such as Superstrings (in 10 dimensions) and Supergravity (in 11 dimensions): namely that the "graviton" in such models is expressed in three related particle fields:

1. The Graviton: A massless* spin-2 tensor boson
2. The Gravivector (or Graviphoton): A massive* spin-1 vector boson
3. The Graviscalar (or Radion): A massive* spin-0 scalar boson

* - Note that massless particles are stable and travel at light speed, decreasing their respective force-mediation via an inverse square relationship. Massive particles are unstable and decay in short order and also have variable speed, and thus transmit forces only over short range with a strength that falls off statistically/exponentially with distance, with a sharp cut-off range.

​

In particle physics, forces are mediated by virtual bosons (such as the photon for electromagnetism) that give rise to purely attractive forces for even-spin bosons and forces that repel like and attract opposite charges for odd-spin bosons.

In the above models, normally the gravivector and graviscalar effects cancel each other out, leaving only the effect of the graviton field (i.e. always attractive with infinite range dropping off as an inverse square with distance). But if the physics of Traveller has a working Unified Field Theory and knows how to manipulate 11-D graviton fields, then isolating the graviphoton and the graviscalar allows the secondary generation of repulsive and attractive forces, but only over short ranges.

 

[Enoki]

But in this case, if you are inside the ship, the "natural" gravity well (however micro) that the ship produces does not come from a specific direction, but all arround you. So, any amplifier will "push" all arround you, not in a specific direction (again, I'm not sure I can explain myself well, I hope you can understand what I mean).

And, assuming the grav belt wrks in a ship's artificial gravity, what would happen if someone manipulates it, changing the grav polarity in quick succession (as would an anti-hijack program do)?

If you go down in a mine shaft gravity still has a direction... So will a ship. The center of mass is the direction of the gravity however weak. That means no matter where you are on the Death Star battleship, gravity emanates from its central point outward.

As for manipulating it, if your system automatically compensates, then it doesn't matter. If not it might get into an interesting physics lesson... Of course, how would shifting the gravitational forces on the ship dramatically and frequently effect it? I don't think the push-pull and flexing that would result would be a good thing...

 

[whulorigan]

I'm not familiar with T4 or T5, but TNE also uses Contra-Grav: It cannot produce thrust, you also need a conventional thruster to move forward. This is for all contra-grav applications, like air/rafts, grav tanks, and grav belts.

In T5, "Lifters" can produce a limited amount of lateral thrust. These are distinct from G-Drives and M-Drives.

 

[McPerth]

Sounds reasonable, but apparently T4 has a description of how this works.

Well, not about how artificial gravity works, or at least I don't remember it.it only says it neutralized gravity with a 98% eficiency...

That is CT, MT Anti-grav, not TNE, T4 Contra-grav.

My comment here was more about artificial gravity than contra-grav proper..

I'm not familiar with T4 or T5, but TNE also uses Contra-Grav: It cannot produce thrust, you also need a conventional thruster to move forward. This is for all contra-grav applications, like air/rafts, grav tanks, and grav belts.

Well, I'm not familiar with TNE, and just a little more about T4 (AFAIK most those matters are carbon copy, though), but the definition of the grav belt baktegon quoted only talks about low-energy thrusters for lateral motion, but asumes you can already fly with contra-grav.

Also, those thrusters (as, IIRC in TNE/T4 there's not thuster thech as in MT, but thrusters are reaction drives) would either need reaction mass or use the atmosphere for it, again being problematic in vacuum...

 

[mike wightman]

I am reminded of a 'funny' scene in Consider Phlebas.

A group of mercenaries decide to loot stuff from one of the big ships that ply the oceans of an orbital - a Culture mini-ringworld that generated gravity through spin.

One of the mercs jumps from the upper superstructure of the ship and activates his grav belt. Sadly spin gravity and grav belts don't interact and as a result... splat.

 

[aramis]

Then a 100 kg body with contragrav will still weight 2 kg...

And still displace ~100.1L of air, massing some 127g...

Actually, they apply it to the acceleration, rather than the weight... so the 9.8 N/kg is reduced to .196 N/kg, and thus 19.6 cm/s² instead of 980 cm/s²...

roughly 0.2 m/s² per G local.
So while mr. 100kg leaps, instead of coming down in 0.5 sec, he comes down in 12 sec.

And a hand cranked turbine, if included in the field, can move enough air for him to fly.. A wingsuit with CG allows hours of soaring.