This is a partial thread that was lost in the recent crash I am sorry that all others in this thread are not included but I only kept my bits.
I am also sorry that the sequence is now a bit jumbled and may not make sense to others who "jump" in.
PhysOrgForum Science, Physics and Technology Discussion Forums -> Nanotechnology & Quantum Physics -> Quantum physics -> wavelengths of macroscopic bodies
Charles J. Quarra Posted on Sep 18 2004, 04:17 PM
Frequently, in introductory quantum mechanics books the relation
between wavelength-momentum is used uncospicuously for macroscopic
objects, probably for didactic purposes, however i see a problem with
that extrapolation: if one would go on and adding the momenta of the
composite objects to obtain a "body-momenta", then one should ask if
why that cant extrapolate to, for example, light beams (as the one you
got on a laser). If there is a system in which one can fulfill the
condition of coherent constructive propagation is in the laser light.
A laser pulse has a lot more total momenta than its constitutive
photons (each produced by an individual atom line) however one doesnt
see this "total momenta wavelength" at work in the physics of these systems, at least nothing im aware.
any insights about this?
Hi Charles J. Quarra,
I have recently added a post to this thread...
PhysOrgForum Science, Physics and Technology Discussion Forums -> News discussions -> Nanotechnology and quantum physics -> Quantum computing is a hoax
It is related to your topic.
I see that there is an unresolved issue here. Photons are the result of electromagnetic emission caused by charge acceleration. This is "not quite" the same as the de Broglie wavelength. A particle has a de Broglie wavelength as a result of motion. The wavelength of a photon is a "special case" of the phenomena. This is because light travels at the constant velocity of C. De Broglie says nothing of an oscillating electromagnetic field for uncharged particles. Yet they too have wavelength. So what is the meaning of this neutral particle travelling with a measurable wavelength?
I guess the point is that light carries no nett charge but is affected by and affects charges. The electromagnetic field (photons) carry/transmit a kind of polarity which is instantaneously electromagnetic and magnetic interlinked field loops (like in a chain, one loop magnetic and then a loop at right angles, electric) that travel frozen with the photons. The wavelength is electromagnetic but is propagated on the space-time continuum that is not electromagnetic (at least in the way we think). The "loops" are able to deform the 4D "surface" of space-time and lock in the disturbance with the apparent passage of the photon. Photons obey Bose-Einstein statistics and so they sum up but are not strictly additive by bulk and have no influence on "fellow travellers". They behave independently and do n
ot influence each other. They do not obey Pauli's Exclusion Principle. Thus the individual wavelengths are unaffected by the wavelengths of other "fellow travellers".
In the case of uncharged particles moving rapidly across the space-time continuum, they also deform the continuum but because the particles obeys Fermi-Dirac statistics the density of the particles will have an upper bound in any small volume. The speed of all particles will be less than the speed of light and so each one is an individual possibly having different velocities. They will obey Pauli Exclusion Principle. Thus they will be additive in the manner you suggest. Thus the wavelength of the "bulk" of a collection of particles will be affected if that is the way they choose to move.
The next question is why the difference? Why can an infinite number of photons dance on the head of a pin and only one particle can exist in a single bit of space at a time? Because they are different! That is why. Light is not the same stuff as other particles. They are the main force carrier in our Universe, they have infinite range, they connect all points of the visible universe with "connection" along null world lines. The particles (us) are the odd ones out. I would point to some of my other posts on this topic.