Afternoon PDT,

I'm admitting to be very light in understanding the Conservation Laws which means that my view is probably totally out to lunch.

However, we have an understanding of how to manipulate magnetic fields which has suggested to some scientists and a great many science fiction authors that gravity can be manipulated using a similar approach.

I probably oversimplifying how magnetic manipulation works and improperly transferring that understanding when trying to imagine how gravity manipulation might be accomplished.

Thank you the information being provided.

Tom Rux

From: "C. Berry" <xxxxxx@gmail.com>
To: "TML" <xxxxxx@simplelists.com>
Sent: Wednesday, August 30, 2017 9:28:13 AM
Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?)

There are definitely things we don't yet know, and technological tricks we don't yet know how to do. The thing is, new discoveries and inventions are exceedingly unlikely to contradict existing theories. Rather, they will make different predictions out at the margins, in conditions that we have not yet encountered (or that we have barely begun to observe).

Newton and Einstein make a good example here. Einstein's theories replaced Newton's, in one sense. Einstein provided a much deeper and more comprehensive description of the universe than Newton did. But -- and this is the key -- the two systems are effectively indistinguishable at small scales of time, velocity, gravity, and so forth. All of our space travel to date has been executed using Newtonian mechanics, because it's massively simpler than Einsteinian mechanics, and for the purpose of mapping out spacecraft trajectories, the difference in the predictions of the two theories are so tiny as to be effectively absent. There's exactly one case I can think of where General Relativity actually does come into play in a practical engineering application, and that's GPS; it depends on timing so exquisitely precise that the GR-induced difference in the rate of time in the satellites compared to the ground (thanks to being at different potentials in Earth's gravity well) has to be taken into account.

So when new physics and new tech come along, it's exceedingly unlikely that we'll throw out things like the main conservation laws; hence the skepticism about the EmDrive. Rather, we'll find new domains where our existing theories begin to diverge from observations, and we'll work out a still more refined model of physics that explains those observations, but reduces to Einsteinian physics in all the domains in which that already worked well.

On Wed, Aug 30, 2017 at 9:11 AM, <tmr0195@comcast.net> wrote:

Morning PDT,

Science fiction is traditionally an extrapolation of known science.I agree that there is a lot we do not know about gravity. Albert Einstein back in 1916 predicted the existence of gravity waves. In 2014 an article came out stating that scientists had detected gravity waves and there have been updates for the past two years.

Gravity waves have been included in a number of science fiction novels, I think the Lensmen series has technology based on gravity waves, unfortunately my books are stored a way in boxes so I cannot verify my memory.

We can manipulate magnetic fields as proven by magnetic levitation used in high speed trains. Again a number of science fiction novels have maglev vehicles long before we built the first one.

Extrapolating what we know about magnetic manipulation someone applied the knowledge, pushed by player comments without a doubt, to contra-gravity and reactionless thrusters. The jump drive is also a guess based on theories we have not been able to prove about other systems like the warp drive.

Most of the science programs I watch have commented on what new technologies have done to improve our knowledge. Many of the new discoveries have altered what we thought was a hard scientific fact.

In another thread someone mentioned throwing pixie or fairy dust, a lot of technology of today fell into that category.

Tom Rux
From: "C. Berry" <xxxxxx@gmail.com>
To: "TML" <xxxxxx@simplelists.com>
Sent: Tuesday, August 29, 2017 10:07:30 AM

Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?)

And that's just it. CG, thruster, and jump power requirements are determined by game-design decisions, not by physics. None of those technologies are consistent with physics as we understand them, so there's no way to do any reality-based calculation that will yield a power requirement. The Traveller design sequences were reasonably well crafted to support the desired background without creating glaring consistency problems in typical situations, which is more than good enough for a game. It's similar to the relationship between video-game physics and real physics; if the game feels enough like reality, people can immerse themselves in it easily, even if it fails in every way to embody key conservation laws and the like.
On Tue, Aug 29, 2017 at 9:56 AM, <tmr0195@comcast.net> wrote:
Morning PDT,

There is more than one Traveller design sequence that requires the drive train/suspension to have a
design power requirement.

CT Striker Book 3 p. 8, MT Referee's Manual pp. 65-66, TNE FF&S Chapter 10, and GURPS Traveller Starships p. 40. I'm not sure but I believe that T4 Core Book QSDS, T4 Book 2 Starships, and T4 book D FF&S have have power requirements.

In CT Striker Book 3 p. 8 each .02 m^3 of grav generator provides 1 ton of thrust and requires .1 megawatts of power from the power plant. On p. 11 a grav vehicle's requires 1G, determined by dividing the grav generators thrust in tons by the vehicles' weight in tons, to keep the vehicle in the air, hovering. If the thrust is less than 1G the vehicle cannot move, I think this means the vehicle is sitting on the ground. Any thrust in excess of 1G is used for movement.

Tom Rux

From: "Tim" <xxxxxx@little-possums.net>
To: "TML" <xxxxxx@simplelists.com>
Sent: Monday, August 28, 2017 8:32:42 PM
Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?)

On Mon, Aug 28, 2017 at 03:49:12PM -0500, Grimmund wrote:
> On Thu, Aug 17, 2017 at 10:00 PM, Tim <xxxxxx@little-possums.net> wrote:
>
>
> > Does Traveller contragrav employ a means that requires constant power
> > input? We don't know.
>
>
> That seems to be a given. If it has a power requirement to operate, that
> implies that lacking such power, it will no longer operate.

In one of the vehicle design sequences, drivetrain/suspension has a
design power requirement also. This does not mean that the wheels
fall off when the power is not supplied (i.e. no longer supports the
vehicle), it just means that without power the vehicle won't
accelerate and that there is a limit to how much power it can handle
without breaking something.

- Tim
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