Talk:Quantum mechanics/Archive 4

message: I understand quantum mechanics just enough, not to make any great discoveries in the field, but enough to understand the basics.  Special Relativity is the same way.  I found something interesting though, relativity implies both wave-particle duality and supersymmetry!  A wave is a carrier of eneergy from place to place.  A paritcle can be viewed as a carrier of mass from place to place. Relativity says energy is the fourth-dimensional extendsion of momentum (which is mass times velosity). This implies that waves are fourth-dimensional extendsion of particles! This also implies that the carriers of energy (Bosons) are extendsions of the carriers of mass (Fermions)! Wave-particle duality and supersymmetry.  It seems so simple I'm surprized that this was overlooked for so many years.--SurrealWarrior 18:35, 20 Jun 2005 (UTC)
thread_title:  Quantum Physicists are just catching up with Relativity! 

message: i have a question about degenerated matter. when a star shrinks, the maxium uncertainty in the position of a particle for example electron decreases, so it minimum uncertainty in momentum increase. what i dont understand is what is uncertainty in momentum? does it mean that the particle is traveling with multiple momentum at the same time? because i read from somewhere as the minimum uncertain momentum increase the particle's minimum velocity increase, and i just dont get it (is it like the particle's velocity can be 0-something?)
Yes, a particle does have multiple momenta and multiple velocities at the same time, just like a particle of light goes through both holes in a diffraction experiment or through both sides of the lens of a camera or telescope.  To really understand this you have to accept that the description of a particle's motion with a single momentum and single position is an approximation that breaks down on a very small scale.  It is the same approximation as Geometric Optics.  To really understand quantum mechanics you need to give up thinking that a particle really is in a single place.  The only reality (though not the only mathematical description of reality†) is the wave function.  If you want to get closer to what you see directly, take up art or literature. --David R. Ingham 17:59, 18 July 2005 (UTC)
thread_title:  uncertainty principle 

message: There seem to be other problems with this paragraph, besides not being elegant physics.
The Schrödinger equation is not a function but a unique and explicit formula for the time development of the wave equation.
Non-locality is a property of equations, not of functions.
If distant particles interact instantaneously, that is not described by the Schrödinger equation, which is local.
Non-locality is physics and not philosophy.
--David R. Ingham 21:19, 24 July 2005 (UTC)
thread_title:  Bohm interpretation 

message: A related topic, Astrophysics is currently nominated on Wikipedia:This week's improvement drive. Come and support the nomination or comment on it.--Fenice 07:31, 6 August 2005 (UTC)
thread_title: Improvement Drive

message: can someone please tell me what is spin? i heard it can be oriented in up and down and its parallel/antiparallel to the local magnetic field, but whats all that "spin 1/2, 2,1, 0"? like everywhere i read about spin it never says what it is, only it is an intrinsic angular momentum. what does that mean? maybe i just dont know when it is telling what it is, can someone just tell me in ordinary language? (not like everyday language, just dont use a technical term in every sentence)
thanks
-protecter
To begin with, it is the angular momentum of a particle, in units of ℏ (h bar is Planck's constant deviede by 2 π).  Angular momentum can change only by integer multiples of ℏ, that is, it is quantized.
--David R. Ingham 23:45, 8 August 2005 (UTC)
thread_title:  spin 

message: In quantum mechanics, the polarization of light and other wave length ranges of electromagnetic radiation is called the spin or helicity of the photons (particles).  Linearly polarized light consists of photons that have a linear combination of positive and negative helicity.--David R. Ingham 17:33, 9 August 2005 (UTC)
thread_title:  Spin of light 

message: Why is it in the category "Unsolved problems in physics"?
:Quantum Theory as it is now is not so much as unsolved as in unsatisfactory.  There is no dyanmic in terms of "collapsing wave funtions" into the eigenstates during measurement.  Its pretty flimsy when it talks about the interaction of "quantum and classical" systems.  These questions are really statistical mechanics problems but the source is in quantum mechanics.  Overall Quantum definatly predicts experiments accurately in its regime.  
:You could say its unsolved in the sense theres no Quantum theory of gravity.  However that quantum is really Quantum Field Theory and not Quantum Mechanics.  
:--Blckavnger 19:59, 17 November 2006 (UTC)
thread_title:  Category 

message: I'm a general studies student and I'm writing an anthropology paper about technology in post-modern society. I'm pretty sure quantum physics is a big part of this but I couldn't understand a thing in this article. Some plain 'explain it to a novice' language would be really nice. Also that this article has recieved so much attention is great but it doesn't help the lay person and in fact it makes one feel kind of intellectually inadequate.
:No slight is intended. In a nutshell, our common-sense ideas about place (ie position in space) would have to change if we truly were to integrate the knowledge of QM into our current civilization; you can model the world at many levels; look at History of science for an overview in the broadest terms. In fact Newtonian physics (1700) (approximating the world with hard spheres and rigid bodies)  is adequate for understanding a huge part of our civilization. We are just now reaping the benefits of Maxwell's equations (1865) with the electronic circuits of today ( not derived from QM). Look at solid state physics (which uses some QM) if you want to see the physical basis of our understanding of microelectronic technology. The precision and repeatability of our integrated circuits are applications of optics, especially photography and cameras, and the ideas behind the printing press (1041) and lithography (1798). But laser physics (1960) and physics of condensed matter (1900-present) is just starting to reap the benefits of the QM viewpoint. In other words, you don't need to understand the QM viewpoint until you start studying physics, engineering and especially chemistry. And you don't meet too many people who worry about the nature of spacetime or matter on an everyday basis. It truly is a subject for specialized study, in our current civilization. --Ancheta Wis 23:25, 26 November 2005 (UTC)
thread_title:  Yeah. Plain English Please