28,519 reputation
184148
bio website lightandmatter.com
location Fullerton, California
age
visits member for 4 years, 1 month
seen 2 hours ago

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.


May
21
comment Why Negative Energy States are Bad
This is total nonsense. The definitions proposed here are not even viable definitions, because they don't handle the zero-mass case. The relativistic relation that works for all masses, including zero mass, is $m^2=E^2-p^2$, which is perfectly compatible with $E<0$. If this elementary classical argument had been correct, then it would have been a schoolboy mistake for Dirac to propose his picture of the Dirac sea.
May
13
awarded  Popular Question
May
8
awarded  Taxonomist
Apr
12
awarded  Necromancer
Mar
29
awarded  Nice Answer
Mar
6
awarded  Nice Answer
Mar
1
awarded  Necromancer
Feb
28
awarded  Nice Answer
Feb
25
awarded  Necromancer
Feb
14
awarded  Popular Question
Feb
11
comment How come some people are claiming that the Big Bang never happened?
This doesn't address the question.
Feb
9
awarded  Good Answer
Feb
6
awarded  Necromancer
Jan
30
awarded  Necromancer
Jan
29
awarded  Necromancer
Jan
24
awarded  general-relativity
Jan
8
awarded  Necromancer
Jan
2
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