42,611 reputation
458136
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 9 months
seen 46 mins ago

Experimental nuclear and particle physicist. These days I'm teaching, but I've spent a lot of time on nucleon structure in fixed target electron scattering and neutrino oscillations using reactors and beam sources.

Been reading Zemansky & Dittman's book on thermodynamics recently. Quote: ``The concept of temperature is rich in interpretations and levels of abstraction.'' Nice.


2h
comment What all has intrinsic spin?
@SebastianRiese A number of people have been throwing that link around a lot lately and trying to imply that it proves something that it doesn't. All that the Einstein-de Haas effect tells you is that spin is angular momentum. But we knew that. It doesn't address why spin can take on values that are forbidden by the quantization of $\mathbf{r}\times\mathbf{p}$, and that is why it doesn't prove that electrons are little whirling balls.
2h
comment Why can gold be drawn out finer than light?
Meh. It takes a strained interpretation to allow that phase to be true. In a natural interpretation it's nonsense because light doesn't have a limiting transverse extent. The "sizes" you've quoted for light are wavelengths (which are longitudinal.) and they also require that "light" be interpreted to mean "visible light". Crappy writing that favors drama over accuracy.
1d
comment Intuitive definition of electromagnetic field
Textbooks aren't interactive. They can't do the demo, so those that take that approach describe some situations. Often one they hope the students will be familiar with. But most of the recent texts I've looked at for intro electrostatics use a fairly definition driven style. The thing is that you don't have to see the demos to understand that the purpose of all this mucking around with abstract concepts is to describe nature; of course if you don't it really helps to have someone put the abstractions in context for you.
1d
comment Intuitive definition of electromagnetic field
Presentation in terms of a formal system or by leading with a bunch of demos is a implementation detail of a particular teaching strategy. I strongly prefer demo-led for introductory courses, but rather like the formal approach for some advanced subjects.
1d
comment Without friction, what happens in our life?
@Acid It was actually a serious comment first and a joke second. The ubiquitous experience of friction muddies the inertia concept in many people's minds and leads to endless difficulty during the first course.
1d
comment Without friction, what happens in our life?
First semester physics becomes so much easier for students to grasp...
1d
comment Is Wikipedia's definition of angular velocity incorrect?
A common first counter-example is a massless bar with two point masses on the ends rotating about a axis through its center that is neither co-linear with nor perpendicular to the bar.
1d
comment Is Wikipedia's definition of angular velocity incorrect?
@0celo7 Watch out for with the claim that the angular momentum is parallel to angular velocity. In general $I$ is a second rank tensor and they are not guaranteed parallel.
1d
comment Shouldn't dark matter distort light and there for be directly detectable?
The word you want is "microlensing", and it is a minor industry these days though it does not distinguish between baryonic and dark matter.
2d
comment Will a string always be tangent to a pulley at 45 degrees above the horizontal?
Grab a pulley (or wheel, or pipe) wrap some string around it and play with it. A taunt string will always be tangent to the object, but can take on any angle.
2d
answered Intuitive definition of electromagnetic field
2d
comment Is displacement in circular motion a chord or an arc?
Instantaneous speed is the magnitude of instantaneous velocity, but that does not mean that average speed is the magnitude of average velocity.
2d
comment Is displacement in circular motion a chord or an arc?
Check in the treatment that you are using the distinction between "displacement" and "distance". After that all should be clear.
2d
comment Bell's inequality, “complete plans” and spooky action at a distance
Bell's theorem has multiple particles in it by construction. There is no Bell's inequality for one particle. You seem to be trying to make an analogy of some kind, but the math does not translate.
Aug
29
comment Does Hooke's Law apply for microscopic amounts of compression?
You'll want to search for "elastic modulus".
Aug
29
comment Why is local realism not possible with QM?
Violations of Bell's inequality don't prove non-locality as such. They prove that at least one of realism and locality fail. Many people are very firmly of the opinion that obviously one of them can't be violated so it must be the other that fails. Alas, not everyone agrees on the identity of the sacrosanct principle.
Aug
29
comment Why is local realism not possible with QM?
Is the question one of why Bell's theorem identifies differing results for the two case, or why people have concluded that Bell's inequality is violated?
Aug
29
comment Earth density distribution from shooting neutrinos?
Time structured beams would overcome the directionality issue, but we (meaning the whole world) can't afford it. DUNE is projected to be almost of a billion dollars and would represent less than one average accelerator+detector pair for the scheme. The neutrino community is still drooling over the idea of a 2500 km beam experiment (shorter magic baseline), but we can't get the rate with the dollars that we have.
Aug
29
revised Earth density distribution from shooting neutrinos?
added 127 characters in body
Aug
29
revised Earth density distribution from shooting neutrinos?
added 280 characters in body