Vacuum Has Drag - Polidicks

[QUOTE] [IMG]http://3.bp.blogspot.com/-NIJWg8hyfUQ/TVWqwBIoK0I/AAAAAAAAKVs/CEmXrazaYk4/s1600/frictionvacuum.jpg[/IMG] The stopping time ranges from cosmic-scale values at low temperatures to much smaller times at higher temperatures. Physical Review A - Thermal and vacuum friction acting on rotating particles The contribution to vacuum and thermal friction coming from magnetic polarization has been shown to be important for highly conductive materials (e.g., gold), and it can actually dominate over its electric counterpart. In contrast, it is almost negligible in less conductive materials such as graphite. In the Casimir effect, vacuum fluctuations of the electromagnetic field exert a force on closely spaced metal plates, a phenomenon that is well understood theoretically and detectable experimentally. Can a related effect occur for rotating systems, in which vacuum fluctuations alter the spin rate of a particle, resulting in rotational drag? Writing in Physical Review A, Alejandro Manjavacas and Javier García de Abajo of the Instituto de Óptica, Madrid, Spain, show theoretically that this should be an experimentally observable effect. The phenomenon of vacuum friction for spinning objects is somewhat different than for the static parallel plates: the accelerating charges in a spinning conductive object interact with the vacuum fluctuations and can emit photons. Earlier work by Manjavacas and García de Abajo tackled the problem with a semiclassical model that employed the fluctuation-dissipation theorem to calculate the overall energy transfer between the spinning particle and the vacuum field. In their new calculations, they take a fully quantum mechanical approach, which not only confirms the semiclassical results but extends the results to molecular systems and magnetic interactions. In addition to their intrinsic interest, the findings may be relevant to understanding the dynamical behavior of cosmic nanoparticles such as interstellar dust and the optical spectra of rotating molecules The full ten page paper [QUOTE]We study the stopping of spinning particles in vacuum. A torque is produced by fluctuations of the vacuum electromagnetic field and the particle polarization. Expressions for the frictional torque and the power radiated by the particle are obtained as a function of rotation velocity and the temperatures of the particle and the surrounding vacuum. We solve this problem following two different approaches: (i) a semiclassical calculation based upon the fluctuation-dissipation theorem (FDT), and (ii) a fully quantum-mechanical theory within the framework of quantum electrodynamics, assuming that the response of the particle is governed by bosonic excitations such as phonons and plasmons. Both calculations lead to identical final expressions, thus confirming the suitability of the FDT to deal with problems that are apparently out of equilibrium, and also providing comprehensive insight into the physical processes underlying thermal and vacuum friction. We adapt the quantum-mechanical theory to describe particles whose electromagnetic response is produced by fermionic excitations. Furthermore, we extend our FDT formalism to fully account for magnetic polarization, which dominates friction when the particle is a good conductor. Finally, we present numerically calculated torques and stopping times for the relevant cases of graphite and gold nanoparticles. [/QUOTE] [/QUOTE] Source: [url]http://nextbigfuture.com/2011/02/vacuum-has-friction-from-effect-similar.html[/url]

Well, it's impossible to have a total vacuum. So this seems to be solved anyway... Although I'm not exactly sure what reason they're giving for [I]this[/I] kind of drag.

[QUOTE=JgcxCub;28009320]Well, it's impossible to have a total vacuum. So this seems to be solved anyway... Although I'm not exactly sure what reason they're giving for [I]this[/I] kind of drag.[/QUOTE] No, it says there is drag even in a perfect (Hypothetical) vacuum.

[QUOTE=JgcxCub;28009320] Although I'm not exactly sure what reason they're giving for [I]this[/I] kind of drag.[/QUOTE] Quantum shenanigans.

Michelson you are a liar

[QUOTE=JgcxCub;28009320]Well, it's impossible to have a total vacuum. So this seems to be solved anyway... Although I'm not exactly sure what reason they're giving for [I]this[/I] kind of drag.[/QUOTE] It isn't. A particle and "field free" ("field free" defined as where there are no sources like charges, current, light or similar or in just in infinite distance) space is defined as total vacuum (which includes unavoidable vacuum fluctuation and therefore residual/self-induced fields). What is impossible is a total void, even less than vacuum within our universe.

[IMG]http://img29.imageshack.us/img29/9018/dysoni.jpg[/IMG] [b]Drag? No it doesn't, it works perfectly.[/b]

What a drag

I was expecting transsexual cleaning supplies

Annoyingly it does make sense, that rotational systems in a field will experience a force and charge etc, but I'm still at the "Consider them one dimensional" stage of my education. I think saying a vacuum is a little misleading though, so I can draw some parallels between this and, for example, hawking radiation, that is to say particles coming from a supposedly total vacuum and causing problems.

So really all this shows is that it's impossible to create a full vacuum?

[QUOTE=Atokniro;28025730]So really all this shows is that it's impossible to create a full vacuum?[/QUOTE] A vacuum itself IS something dude, every particle will realistically experience drag when it moves unless you can somehow literally remove the fabric of existence from it's path, in which case you are literally hurling kippers into a kettle.

[QUOTE=carcarcargo;28013910]What a drag[/QUOTE] No.

Further proof that rotation is absolute. Whereas we can't say with certainty that the Universe has one origin, i.e. we can't say that the location of an object is absolute, we apparently [i]can[/i] say that it's not rotating and so rotation is absolute.

[QUOTE=Shenanagoats;28025741]A vacuum itself IS something dude, every particle will realistically experience drag when it moves unless you can somehow literally remove the fabric of existence from it's path, in which case you are literally hurling kippers into a kettle.[/QUOTE] I was with you until you started hurling kippers into a kettle.

[QUOTE=ThePuska;28026780]Further proof that rotation is absolute. Whereas we can't say with certainty that the Universe has one origin, i.e. we can't say that the location of an object is absolute, we apparently [i]can[/i] say that it's not rotating and so rotation is absolute.[/QUOTE] Not according to the equivalence principle

[QUOTE=ThePuska;28026780]Further proof that rotation is absolute. Whereas we can't say with certainty that the Universe has one origin, i.e. we can't say that the location of an object is absolute, we apparently [i]can[/i] say that it's not rotating and so rotation is absolute.[/QUOTE] We can say that a particle is rotating. Let's say the universe is totally empty but for 2 particles in a far distance. Now we can say if one is rotating or not by looking at it's local frame of reference. If we see the other particle "moving around you", it's obvious that we must rotate, since both particles are separated by a huge distance by definition and therefore the other particle "moving around you" can't move around because otherwise it'd need to exceed the speed of light (far distance).

[QUOTE=JohnnyMo1;28028633]Not according to the equivalence principle[/QUOTE] Please clarify

[QUOTE=ThePuska;28031847]Please clarify[/QUOTE] Any acceleration is interchangeable with an appropriately described gravitational field.

[QUOTE=JohnnyMo1;28034408]Any acceleration is interchangeable with an appropriately described gravitational field.[/QUOTE] I don't see the connection. How do you get from the equivalence principle to the conclusion that rotation can't be absolute?

[QUOTE=JohnnyMo1;28034408]Any acceleration is interchangeable with an appropriately described gravitational field.[/QUOTE] :psyboom: I'm an engineering student and even I am having a hard time wrapping my mind around that.

[QUOTE=ThePuska;28037239]I don't see the connection. How do you get from the equivalence principle to the conclusion that rotation can't be absolute?[/QUOTE] Rotation involves a permanent acceleration. Every local accelerated or rotating frame of reference is not an inertial frame of reference and therefore falls under general [u]relativity[/u] (and therefore is not absolute) and therefore the equivalence principle can be applied.