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Author Topic: When to the particles disappear?  (Read 1298 times)

Offline Fozzie

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When to the particles disappear?
« on: 19/07/2010 15:56:35 »
Light exhibits properties of both waves and particles, so if we shift the wavelength, down through infra-red to radio and beyond, at what point does the particle properties of the radiation cease to exist?


 

Offline Soul Surfer

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When to the particles disappear?
« Reply #1 on: 19/07/2010 23:29:36 »
In theory there is no lower limit, but at low frequencies individual quanta have such low energies that they cannot be detected individually and they are usually generated in large quantities by large scale "classical" interactions associated with currents flowing or broadband thermal noise produced by non resonant particle interactions.  The lowest frequency spectrum line that is used is the 21cm (microwave) hyperfine interaction in a molecule of hydrogen  This is at the top end of the radio spectrum.    Nuclear magnetic resonance is also a quantum process that can involve precise frequencies right down into the Megahertz range but the quanta are only detected in large numbers.
 

Offline syhprum

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When to the particles disappear?
« Reply #2 on: 20/07/2010 08:43:24 »
I take it the energy of individual photons can be calculated hence their apparent mass, does the Planck mass limit come into play ?.
 

Offline Soul Surfer

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When to the particles disappear?
« Reply #3 on: 21/07/2010 09:53:03 »
I am not sure what you mean by this syhprum the Planck mass is quite a large mass ( around 20 micrograms much greater than any currently known massive particles and in theory measurable using a balance!) and photons only have momentum and no mass and there is no reason why this should not be arbitrarily small subject only to the "size" of the universe.
 

Offline Soul Surfer

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When to the particles disappear?
« Reply #4 on: 21/07/2010 10:07:33 »
It is interesting to note that the opposite effect occurs, particles also behave a waves depending on their momentum in a particular frame of reference and as particles slow down they become more fuzzy and indistinct, in effect bigger.

Electrons are the lightest of the easily detectable particles and it is their inherent fuzzyness that in effect creates the size of atoms.

If you slow down (cool) neutral particles with no residual spin like some atoms it is possible to get the wavelengths of the particles so long that individual atoms become totally indistinct and link together to form a Bose Einstein condensation.  this can behave like a sincgle composite "particle" in a quantum mechanical sense.
 

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When to the particles disappear?
« Reply #4 on: 21/07/2010 10:07:33 »

 

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