Does a Buckyball spin like an electron or like a baseball?

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Discussion Overview

The discussion centers around the comparison of the spin of a Buckyball to that of an electron and a baseball. Participants explore the nature of spin in quantum mechanics versus classical mechanics, questioning how these concepts apply to different molecules and particles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Jim Graber questions whether a Buckyball spins more like an electron or a baseball, and seeks to understand the dividing line between these types of spin.
  • Some participants clarify that quantum spin is fundamentally different from classical spin, with quantum spin being an intrinsic property that does not represent physical spinning motion.
  • One participant notes that while electrons have quantum spin, Buckyballs can exhibit classical angular momentum, suggesting they spin more like a baseball.
  • There is a query about the angular moments of inertia for various molecules, including Buckyballs and others, indicating a need for specific data to support the discussion.
  • A participant introduces the idea of quantized rotation in diatomic molecules, suggesting they rotate more like a baseball, while acknowledging that this rotation is also quantized.
  • Another participant mentions the intrinsic spin of a Buckyball, questioning how the electrons contribute to this property and whether it is significant.
  • There is a discussion about the implications of quantum spin in the context of black holes and angular momentum conservation, raising further questions about the relationship between intrinsic spin and orbital motion.

Areas of Agreement / Disagreement

Participants express differing views on the nature of spin, with some emphasizing the distinction between quantum and classical spin while others suggest similarities. The discussion remains unresolved regarding the exact nature of Buckyball spin in relation to electrons and baseballs.

Contextual Notes

Participants note the lack of specific data on angular moments of inertia for molecules, and there are unresolved questions about the implications of quantum spin in various contexts.

Who May Find This Useful

This discussion may be of interest to those studying quantum mechanics, molecular physics, and the properties of angular momentum in both classical and quantum systems.

jimgraber
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Does a Buckyball spin like an electron or like a baseball?

We are often told that an electron does not really spin like a baseball.

Only one (or two, if you count up and down) spin states, for example.

How about a Buckyball?

Does it spin more like an electron, or more like a baseball?

Where is the dividing line?

How can you measure the difference?

TIA,

Jim Graber
 
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What are the angular moments of inertia of "buckeyballs," adamantane, SF6, Xe, and an electron?
 
Quantum spin isn't the same thing as spin the way a baseball turns. Elementary particles, hadrons, and nuclei have quantum spin, which is an intrinsic characteristic of it, but doesn't actually represent spinning motion (an electron doesn't even contain 1 spin, it's 1/2 spin.) An electron doesn't spin like a top, it just has spin.

A bucky ball can spin in space like a top, ergo, it's classical angular momentum.

As far as I know, there can't be a dividing line because these are two different things?
 
Bystander said:
What are the angular moments of inertia of "buckeyballs," adamantane, SF6, Xe, and an electron?
I read your reply to suggest that all but electrons spin like baseballs. Is this what you intended?
If so, the dividing line is smaller than I expected. What about a proton or a neutron? Do they also spin like baseballs?
 
Nerp.
 
I googled around a bit and found this nice write up on why a classical spin model for an electron does not work:
http://www.physicspages.com/2013/01/16/electron-as-a-classical-spinning-sphere/
I did not find any useful angular moment of inertia for molecules. Wolfram alpha kept giving me the moment of inertia at a distance of one meter.
I still do not have any reputable reference that would help answer my questions.
 
I wonder how it would be to try spinning a molecule like tri-substituted methane with one Florine, one Chlorine and one Bromine, ie HCFClBr.At least in theory you could tell what direction it was pointing.
 
This nice reference on rotational spectroscopy

http://hyperphysics.phy-astr.gsu.edu/hbase/molecule/rotrig.html

seems to discuss a diatomic molecule rotating almost like a baseball, except that the rotation is quantized in discrete steps.

So does a diatomic molecule rotate more like an electron or more like a baseball?

I think the answer is more like a baseball.I guess you can always say the rotation of the baseball is also quantized into discrete steps, just very small ones
 
jimgraber said:
moment of inertia for molecules
Bond lengths of molecules (inter-nuclear distances) are O(0.1 nm). Moments are O(10-47) (H2) to O(10-40(?)) kgm2.
 
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  • #10
A buckyball might have intrinsic spin (the purely QM property) - not sure how all the electrons add up. Even if it has, it is small.
It can certainly rotate (the thing with classical equivalent) - the rotation will still be quantized but a classical rotation is probably not a bad model for such a large molecule.
 
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  • #11
I have never understood this myself. The point is often made that quantum spin is different than classical spin. But quantum spin is still quantized angular momentum. These things are not totally unrelated.

Maybe a different way to ask the question. What happens if a black hole eats a lot of polarized light? To conserve angular momentum something has to give. Does the black hole spin faster or does it have some kind of large quantum spin number attached to it?
 
  • #12
The black hole will spin faster.

Intrinsic particle spin and orbital motion differ in their g-factor. For orbital motion it is always 1, for particle spins it is not.
 
  • #13
Great, now if I can wrap my head around what this g-factor is I may learn something.
 

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