Questions on world-line
in [Relativity]
|
From: YBM on 23 Aug 2006 13:07 kenseto a ?crit : > The point is: worldline or trajectory in spacetime requires some kind of > motion to happen. In SR there is only relative motion.....does that mean > that worldline of an object is the result of relative motion?? I should be dreaming... You are just about to get it !
From: Igor on 23 Aug 2006 13:16 kenseto wrote: > "Igor" <thoovler(a)excite.com> wrote in message > news:1156349832.759078.175940(a)74g2000cwt.googlegroups.com... > > > > kenseto wrote: > > > "Igor" <thoovler(a)excite.com> wrote in message > > > news:1156265582.026355.324580(a)p79g2000cwp.googlegroups.com... > > > > > > > > kenseto wrote: > > > > > In SR the world line is the path of an object in space with the > passage > > > of > > > > > time. > > > > > > > > Not quite. It's literally the path taken through spacetime. > > > > > > > > >Each object has its own world-line. > > > > > > > > Yes. > > > > > > > > > > > > > Questions: > > > > > 1. Does this mean that the world-line of an object is the result of > the > > > > > individual motion of the object? > > > > > > > > Yes, through spacetime, but as opposed to what? > > > > > > > > > 2. SR says that there is no such thing as individual motion. > > > > > > > > Depends on what you mean by individual motion. If you mean absolute, > > > > then you're correct. > > > > > > > > >There is only > > > > > relative motion then how does an individual object have world-line? > > > > > > > > The world line is fixed in spacetime. It's invariant, so everyone > > > > agrees on the path. How you define the coordinate system, however, is > > > > entirely up to you. That's where relative motion comes in. > > > > > > > The question is: how does an object have world line? What make it trace > out > > > a world line? > > > > The best analogy would be a trajectory in spacetime. What makes a body > > have a trajectory? In classical physics, all bodies have a unique > > trajectory, as opposed to QM, where their trajectories become smeared > > over many different paths. > > > The point is: worldline or trajectory in spacetime requires some kind of > motion to happen. In SR there is only relative motion.....does that mean > that worldline of an object is the result of relative motion?? The worldline is invariant. Motion is relative. That's all there is to it. Beyond that, I don't really understand what you're even asking.
From: Ahmed Ouahi, Architect on 23 Aug 2006 13:43 However, a certainly, as for instance, when anyone would be tracing the surface of the earth as it would look from a high a distance out in a space. Therefore, the line always goes up and down, a systematically along an infinite amount of a trees as along an infinite amount of a buildings. However, otherwise, at first the surface would get a smoother, as the roundness of anything as of the hoods passes a definitely out of a view, when especially, it would be seen along anything or along any mechanical zooming, which it would be an apparently along a random way, a definitely as a matter a fact. -- Ahmed Ouahi, Architect Best Regards! "kenseto" <kenseto(a)erinet.com> wrote in message news:2p%Gg.68962$u11.35108(a)tornado.ohiordc.rr.com... > > "Igor" <thoovler(a)excite.com> wrote in message > news:1156349832.759078.175940(a)74g2000cwt.googlegroups.com... > > > > kenseto wrote: > > > "Igor" <thoovler(a)excite.com> wrote in message > > > news:1156265582.026355.324580(a)p79g2000cwp.googlegroups.com... > > > > > > > > kenseto wrote: > > > > > In SR the world line is the path of an object in space with the > passage > > > of > > > > > time. > > > > > > > > Not quite. It's literally the path taken through spacetime. > > > > > > > > >Each object has its own world-line. > > > > > > > > Yes. > > > > > > > > > > > > > Questions: > > > > > 1. Does this mean that the world-line of an object is the result of > the > > > > > individual motion of the object? > > > > > > > > Yes, through spacetime, but as opposed to what? > > > > > > > > > 2. SR says that there is no such thing as individual motion. > > > > > > > > Depends on what you mean by individual motion. If you mean absolute, > > > > then you're correct. > > > > > > > > >There is only > > > > > relative motion then how does an individual object have world-line? > > > > > > > > The world line is fixed in spacetime. It's invariant, so everyone > > > > agrees on the path. How you define the coordinate system, however, is > > > > entirely up to you. That's where relative motion comes in. > > > > > > > The question is: how does an object have world line? What make it trace > out > > > a world line? > > > > The best analogy would be a trajectory in spacetime. What makes a body > > have a trajectory? In classical physics, all bodies have a unique > > trajectory, as opposed to QM, where their trajectories become smeared > > over many different paths. > > > The point is: worldline or trajectory in spacetime requires some kind of > motion to happen. In SR there is only relative motion.....does that mean > that worldline of an object is the result of relative motion?? > >
From: kenseto on 23 Aug 2006 15:44 "YBM" <ybmess(a)nooos.fr> wrote in message news:44ec8a99$0$19782$636a55ce(a)news.free.fr... > kenseto a ?crit : > > The point is: worldline or trajectory in spacetime requires some kind of > > motion to happen. In SR there is only relative motion.....does that mean > > that worldline of an object is the result of relative motion?? > > I should be dreaming... You are just about to get it ! RFOTFLOL this idiot falls into the trap.....an object doesn't need any reference to have a worldline.
From: kenseto on 23 Aug 2006 15:47
"Igor" <thoovler(a)excite.com> wrote in message news:1156353371.333406.159360(a)i42g2000cwa.googlegroups.com... > > kenseto wrote: > > "Igor" <thoovler(a)excite.com> wrote in message > > news:1156349832.759078.175940(a)74g2000cwt.googlegroups.com... > > > > > > kenseto wrote: > > > > "Igor" <thoovler(a)excite.com> wrote in message > > > > news:1156265582.026355.324580(a)p79g2000cwp.googlegroups.com... > > > > > > > > > > kenseto wrote: > > > > > > In SR the world line is the path of an object in space with the > > passage > > > > of > > > > > > time. > > > > > > > > > > Not quite. It's literally the path taken through spacetime. > > > > > > > > > > >Each object has its own world-line. > > > > > > > > > > Yes. > > > > > > > > > > > > > > > > Questions: > > > > > > 1. Does this mean that the world-line of an object is the result of > > the > > > > > > individual motion of the object? > > > > > > > > > > Yes, through spacetime, but as opposed to what? > > > > > > > > > > > 2. SR says that there is no such thing as individual motion. > > > > > > > > > > Depends on what you mean by individual motion. If you mean absolute, > > > > > then you're correct. > > > > > > > > > > >There is only > > > > > > relative motion then how does an individual object have world-line? > > > > > > > > > > The world line is fixed in spacetime. It's invariant, so everyone > > > > > agrees on the path. How you define the coordinate system, however, is > > > > > entirely up to you. That's where relative motion comes in. > > > > > > > > > The question is: how does an object have world line? What make it trace > > out > > > > a world line? > > > > > > The best analogy would be a trajectory in spacetime. What makes a body > > > have a trajectory? In classical physics, all bodies have a unique > > > trajectory, as opposed to QM, where their trajectories become smeared > > > over many different paths. > > > > > The point is: worldline or trajectory in spacetime requires some kind of > > motion to happen. In SR there is only relative motion.....does that mean > > that worldline of an object is the result of relative motion?? > > The worldline is invariant. Motion is relative. That's all there is > to it. Beyond that, I don't really understand what you're even asking. > What I am asking is: what motion of an object that gives rise to it worldline? Is it the object's absolute motion (individual motion)? If not why not? Ken Seto |