Starship Asterisk*

heehaw wrote: ↑Mon Jan 11, 2016 10:04 pm
This is a good discussion, actually. Got me thinking. I really suggest an APOD of a white dwarf (Procyon and its wd companion would be ideal) and refer to Procyon and its quantum-mechanical white dwarf companion. That would be a use of "quantum-mechanical" that would be totally appropriate, because the only thing that keeps a white dwarf star from collapsing is the Heisenberg Uncertainty Principle, which is unequivocally quantum mechanical. And yet the object, the star, is macroscopic!

Chris Peterson wrote:

manfred the cat wrote:Hi everyone,
I'm just wondering why it is said that the effect is "quantum mechanical diffraction of light"? Just because photons are both particles and waves? One usually do not describe a regular rainbow as being "quantum". Diffraction is not a quantum phenomenon, light dispersion isn't either.

Diffraction requires quantum mechanics for a complete description. It is reasonably called "quantum mechanical". However, since this particular phenomenon is adequately described by the classical treatment of diffraction (and far simpler than a QM analysis!), the qualification in this case seems unnecessary and potentially confusing.

Douglas Hofstadter wrote:

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<<"In the end, we self-perceiving, self-inventing, locked-in mirages are little miracles of self-reference. […] Our very nature is such as to prevent us from fully understanding its very nature. Poised midway between the unvisualizable cosmic vastness of curved spacetime and the dubious, shadowy flickerings of charged quanta, we human beings, more like rainbows and mirages than like raindrops or boulders, are unpredictable self-writing poems — vague, metaphorical, ambiguous, and sometimes exceedingly beautiful."

- (Epilogue: _I Am a Strange Loop_, p. 363 )

manfred the cat wrote:Hi everyone,
I'm just wondering why it is said that the effect is "quantum mechanical diffraction of light"? Just because photons are both particles and waves? One usually do not describe a regular rainbow as being "quantum". Diffraction is not a quantum phenomenon, light dispersion isn't either.

Les Cowley wrote:About corona formation here:
http://www.atoptics.co.uk/droplets/corform.htm
It's a straightforward wave diffraction effect - Nothing to do with quantum mechanics.

The first thing that struck me was the slight asymmetry of the circles (wider at the top and narrower at the bottom).

manfred the cat wrote:Hi everyone,
I'm just wondering why it is said that the effect is "quantum mechanical diffraction of light"? Just because photons are both particles and waves? One usually do not describe a regular rainbow as being "quantum". Diffraction is not a quantum phenomenon, light dispersion isn't either. Am I missing something?
Thanks for your comments.
jl.

Beyond wrote:What an unusually nice picture of our neighborhood star. My first thought when i saw it, was 'Ann'. I think It would make a very good avatar for a color commentator.

Guest wrote:When it says "A corona visible only to Earth observers", is that just badly worded? I would have thought that a corona would be visible of any planet (Venus & gas giants excluded), including Pluto and moons with atmospheric vapor, where diffraction may occur. Would it matter what the atmospheric vapor was made of? Would a cloud of (perhaps) methane diffract differently?