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bio website lightandmatter.com
location Fullerton, California
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visits member for 3 years, 11 months
seen May 21 at 15:35

I teach physics at Fullerton College, a community college in Southern California. I have an undergrad degree in math and physics from Berkeley and a PhD in physics from Yale. Back when I was doing research, my field was experimental low-energy nuclear physics.


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awarded  general-relativity
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comment Energy Required to Rip Spacetime
It sounds like you're referring to topology change. The classic paper on this topic is by Geroch, adsabs.harvard.edu/abs/1967JMP.....8..782G . Here is a more recent discussion: arxiv.org/abs/gr-qc/9406053 . Geroch showed that there must be either CTCs or a violation of the weak energy condition.
Dec
29
comment Why are electromagnetic waves not able to pass through a hole with a diameter smaller than the wavelength?
But if they are close together...closer than the wavelength of the radiation...then they represent two coherent sources whose amplitudes add. So you get FOUR times the power. Diameter-to-the-fourth. (Because it doesn't matter if the two holes are merged into one.) Two mistakes here. (1) Two holes side by side do not constitute a hole with twice the diameter. (2) If power goes like the fourth power of the diameter, and you double the diameter, then you get 16 times the power, not four times. For a correct explanation of the exponent, see the questions that this question duplicates.
Dec
27
revised Why are electromagnetic waves not able to pass through a hole with a diameter smaller than the wavelength?
remove quantum-mechanics tag; add diffraction
Dec
27
comment Why are electromagnetic waves not able to pass through a hole with a diameter smaller than the wavelength?
duplicate of physics.stackexchange.com/q/141556 and physics.stackexchange.com/q/141562
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Dec
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comment Has relativity of simultaneity been directly observed?
[...] test theory, which is provided by the SME of Colladay and Kostelecky, arxiv.org/abs/hep-ph/9809521 . A vast amount of data has tightly constrained the Lorentz-violating parameters of the SME: arxiv.org/abs/0801.0287
Dec
7
comment Has relativity of simultaneity been directly observed?
[...] simultaneity becomes absolute in that sense. That doesn't mean that the many tests of the relativity of simultaneity become invalidated. We've experimentally verified that different observers get different results when they carry out synchronization. A preferred frame would just tell us that one privileged observer's result was preferred. Furthermore, RMS is purely a kinematic theory, and therefore its parameters would be specific to a certain measuring device, such as a specific kind of clock. Null results from clock-comparison experiments tell us that we really need a dynamical [...]
Dec
7
comment Has relativity of simultaneity been directly observed?
This is a misinterpretation both of the RMS test theory and of this type of test theory in general. In the current fundamental theories of physics, Lorentz invariance is taken to be exact, and that means that regardless of the precision with which we can verify LI, it is still vulnerable to falsification by a later, more precise experiment. Any such hypothetical future falsification of LI would presumably lead to the existence of a preferred frame, since LI is mainly a statement of the nonexistence of preferred frames. Given a preferred frame, we have a preferred time coordinate, and [...]
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