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HNQ
9:05 AM
2
Q: What vector field property means β€œis the curl of another vector field?”

Matthew LeingangI'm an undergraduate mathematics educator and I teach a lot of multivariable calculus. I posed this question on MSE over four years ago and I haven't gotten any definitive answers (despite 12 upvotes and a bounty posted). It could be there's no answer, but someone suggested I ask on this forum....

 
 
12 hours later…
HNQ
8:38 PM
3
Q: Physical interpretation of gamma matrices

Matrix001Just out of plain curiosity, I want to ask: What are/is the physical interpretation(s) of the gamma matrices? If there is none, is it right to assume that it is just a mathematical fudge-factor?

 
 
2 hours later…
HNQ
10:20 PM
2
Q: Is a geodesic in the 4d spacetime still a geodesic after projection onto the 3d space?

Yuhang ChenAccording to Einstein's general relativity, a free object traces a geodesic in the 4d curved spacetime. But what we can observe is the projected path of the object onto the 3d space, which is itself a Riemannian manifold, with the inherited Riemannian metric from the spacetime. Is the projec...

 

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