Re: Landing vs hovering (was Re: [TML] What class of Port is this?) Phil Pugliese 31 Aug 2017 10:15 UTC
This all reminds of a college physics class I took once. The prof recommended that we attend a seminar given by a prominent visiting theoretical physicist. Being the big-time sci-fi buff that I was, I alternated, while listening to his cutting-edge speculations, between, "WOW! COOL!" & "OH, BUMMER!". -------------------------------------------- On Wed, 8/30/17, <xxxxxx@comcast.net> wrote: Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?) To: "TML" <xxxxxx@simplelists.com> Date: Wednesday, August 30, 2017, 2:36 PM Hello again, You mean I won't be getting a grav belt for Christmas. Boy you sure know how to ruin my day.;-) Tom Rux From: "C. Berry" <xxxxxx@gmail.com> To: "TML" <xxxxxx@simplelists.com> Sent: Wednesday, August 30, 2017 2:07:59 PM Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?) We find it relatively easy to manipulate magnets because (a) they're dipoles, and (b) electricity and magnetism are really just two "facets" of a single force, electromagnetism. This means you can create magnetic fields by moving electric fields by moving magnets (e.g. in a generator), or create magnetic fields by moving charged particles (e.g., in an electromagnet). Indeed, light itself is just a self-propagating oscillation between electric and magnetic forces, each inducing the other as it changes. It's all qute beautiful, really; Maxwell's famous four equationsexpress everything you need to know about electromagnetism. In college, I had a tattered and beloved t-shirt with the differential formulation of these equations on it. :) There are three other known forces in our Universe; the strong and weak nuclear forces, which are responsible for various very short-range interactions between particles (e.g. binding atomic nuclei together despite the mutual electromagnetic repulsion of protons) and gravity. Current theories indicate that the electromagnetic, weak, and strong forces are actually just aspects of a single force, much like electricity and magneticism, and that in high enough energy regimes they "unify" -- that is, cease to be distinct from one another. If this is correct, there are really only two forces, EM+strong+weak and gravity. Gravity seems to be very different, as it's not so much "in" the universe as it "is" the universe. Gravity is a manifestation of the curvature of space-time caused by massive objects. One of the great unsolved problems in modern physics is "Grand Unification", a single theory that would account for all forces in a single formulation, similar in spirit to Maxwell's equations. Physicists know that our current understandings of General Relativity (which explains gravity) and the Standard Model (which explains quantum phenomena) are irreconcilable. Each makes nonsensical predictions (or fails entirely, with the equivalent of dividing by zero) in extreme domains of the other. So clearly there is something fundamental we have yet to understand. Some "Grand Unified Theory" (or GUT, as physicists say) may one day come along that reduces to GR or the SM in the appropriate domains, but also accounts for the cases we currently can't handle. It would be very cool if this happened while I'm still alive, as I'm very eager to know the answer. :> If we succeed in unifying the forces, it just may prove to be possible to manipulate gravity via the other forces, as we currently manipulate magnetism with electricity and vice versa. But that's very, very, VERY speculative, and again, given the special role gravity plays in the universe, I find it unlikely -- however much I really, really want an air-raft for my birthday. :> On Wed, Aug 30, 2017 at 1:35 PM, <xxxxxx@comcast.net> wrote: 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, <xxxxxx@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, <xxxxxx@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 ----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com ----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go tohttp://archives.simplelists.com -- "Eternity is in love with the productions of time." - William Blake----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com ----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com -- "Eternity is in love with the productions of time." - William Blake----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com ----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com -- "Eternity is in love with the productions of time." - William Blake----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://archives.simplelists.com ----- The Traveller Mailing List Archives at http://archives.simplelists.com/tml Report problems to xxxxxx@simplelists.com To unsubscribe from this list please go to http://www.simplelists.com/confirm.php?u=EwREIRgLK8vaUEhNlnoNdSGKwnjoID8a