- #1
Robert100
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When I was learning about gravity, I was taught that F = [G(m1)(m2)]/r^2, and that this equation was valid for r (the distance between mass 1 and mass 2) at all distance scales. However I now know better: Physicists today admit that we do not know that this relationship is true at all scales, and that it hasn't even been properly tested on any scales less than 1mm, or greater than 1 galaxy diameter. In fact a small but growing number of physicists now hold that the existence of dark matter is not a given, but only appears to exist if we assume that our understanding of gravitational force works the same on all scales. Hence new hypotheses such as MOND.
I always wondered if the same was true with matter having de Broglie wavelengths. As bizarre as this idea is, I accept the experimental results that matter, from the scale of electrons up to atoms, does have a fullerene wavelength. If I understand correctly, experiments have been carried out that demonstrate de Broglie wave diffraction of C60 fullerenes, which really blows my mind. (But my mind does not constrain reality!)
First question: Is it controversial that we are detecting wave like properties of a large molecule? Wouldn't that imply that "large" objects like molecules don't have any physical existence without an observation? Yet we exist, and we are made of molecules. What causes us to appear as classical objects when we are not being observed? Decoherence? (That would be an acceptable answer, IMO.) Or is anyone claiming that the results of this experiment have been misunderstood, and we are not seeing wavelike diffraction in C60 in the same way that electrons diffract?
In fact, does QM obligate us to believe that large objects (say, larger than a human cell) actually have any de Broglie wavelength at all? After all, many physicists are now holding that there may be fundamental limits on length, the Plack scale, and that space itself may be quantized. So if an object is massive enough to have a wavelength less than Plack scale, doesn't that imply that it may not have a de Broglie wavelength?
I add for clarification a discussion from Wikipedia, from the Wave-Particle Duality article. Any thoughts?
--- begin quote ---
In 1999, the diffraction of C60 fullerenes by researchers from the University of Vienna was reported1. Fullerenes are rather large and massive objects, having an atomic mass of about 720. The de Broglie wavelength is 2.5 picometers, whereas the diameter of the molecule is about 1 nanometer, i.e. about 400 times larger. As of 2005, this is the largest object for which quantum-mechanical wave-like properties have been directly observed. The interpretation of the experiment remains controversial because these experimenters have assumed the arguments of wave-particle duality and have assumed the validity of de Broglie's equation in their argument.
Whether objects heavier than the Planck mass (about the weight of a large bacterium) have a de Broglie wavelength is theoretically unclear and experimentally unreachable. The wavelength would be smaller than the Planck length, a scale at which current theories of physics may break down or need to be replaced by more general ones.
--- end quote ---
Thoughts?
Robert
I always wondered if the same was true with matter having de Broglie wavelengths. As bizarre as this idea is, I accept the experimental results that matter, from the scale of electrons up to atoms, does have a fullerene wavelength. If I understand correctly, experiments have been carried out that demonstrate de Broglie wave diffraction of C60 fullerenes, which really blows my mind. (But my mind does not constrain reality!)
First question: Is it controversial that we are detecting wave like properties of a large molecule? Wouldn't that imply that "large" objects like molecules don't have any physical existence without an observation? Yet we exist, and we are made of molecules. What causes us to appear as classical objects when we are not being observed? Decoherence? (That would be an acceptable answer, IMO.) Or is anyone claiming that the results of this experiment have been misunderstood, and we are not seeing wavelike diffraction in C60 in the same way that electrons diffract?
In fact, does QM obligate us to believe that large objects (say, larger than a human cell) actually have any de Broglie wavelength at all? After all, many physicists are now holding that there may be fundamental limits on length, the Plack scale, and that space itself may be quantized. So if an object is massive enough to have a wavelength less than Plack scale, doesn't that imply that it may not have a de Broglie wavelength?
I add for clarification a discussion from Wikipedia, from the Wave-Particle Duality article. Any thoughts?
--- begin quote ---
In 1999, the diffraction of C60 fullerenes by researchers from the University of Vienna was reported1. Fullerenes are rather large and massive objects, having an atomic mass of about 720. The de Broglie wavelength is 2.5 picometers, whereas the diameter of the molecule is about 1 nanometer, i.e. about 400 times larger. As of 2005, this is the largest object for which quantum-mechanical wave-like properties have been directly observed. The interpretation of the experiment remains controversial because these experimenters have assumed the arguments of wave-particle duality and have assumed the validity of de Broglie's equation in their argument.
Whether objects heavier than the Planck mass (about the weight of a large bacterium) have a de Broglie wavelength is theoretically unclear and experimentally unreachable. The wavelength would be smaller than the Planck length, a scale at which current theories of physics may break down or need to be replaced by more general ones.
--- end quote ---
Thoughts?
Robert