35,276 reputation
348120
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 4 years
seen 11 hours 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.


Nov
23
revised Should a Gaussian Curve Always Be Drawn Symmetrically?
Edit to reflect the real question.
Nov
23
comment Stuck on Snell's Law
You seem to misunderstand the underlying algebra here. In particular "I didn't use inverse sin as this would just take me back to 25 degrees." represents a place where you are confused about the math.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
Of course, if you have asymmetric tails it's worth looking closely at the physics. If there is a resonance there then you expect a Lorentzian to be a better fit, anyway.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
Again, assuming that Floris hit on the OP's real question it is not about statistics at all. It's about a feature of the graphical plotting of functions. Not really meat for either site, but a side-issue that many students encounter at some point.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
Assuming that Floris nailed your complaint, you wanted to ask something like: "As plotted the orange line is not symmetric, but it is supposed to represent a symmetric functions (a Gaussian). How can this be right?" It is important to focus our attention on the right feature(s) of the figure. Because you asked about the "fit" several of us were looking at the relationship between your data and the fit-function and trying to figure out what was bugging you.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
A general word for what has happened with the plotted points of the function not being symmetric is "aliasing" (which has several other, related, meanings in the graphics world). That is, as Floris says, to be expected unless you force the relationship between the mean and the plotted point to be symmetric.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
Mind you, with the amount of data that you have all those things are to be expected.
Nov
23
comment Should a Gaussian Curve Always Be Drawn Symmetrically?
You may need to specify the question better. A Gaussian function is symmetric about it's mean by construction. It can't help it. So, what is the asymmetry that is bothering you? That the mean is not quite zero? That the fit may be underestimating one tail and over estimating the other. That they data simply have some scatter?
Nov
23
comment Why are neutrons present in an atom?
Is the question "Why should it be this way?" or "How do we know that it is this way?". The former can be answered in therms of QHD but because philosophical if pushed to the limit. The latter is clearly a physics question.
Nov
23
comment Energy resolution of LHC Electromagnetic Calorimeter
When you look at a (segmented) calorimeter, you do apply some process to select a bunch of hits which you are treating as belonging together. Then you add up the energy those hits represent and that sum is your $E$. The selection process is important and for a calorimeter in a colider experiment it is unlikely to be "just take it all" the way it might be in a low rate experiment.
Nov
23
comment If a neutrino has a rest frame, why can't a photon have a rest frame as well?
The problem is not using these wonky, almost-right ways of talking, it's trying to answer this question in this way. You give an impression that will only lead the beginning student astray.
Nov
23
comment Determine reactance force of four load cells arranged in two dimensions
You exhibit a system of equations. You solve the reverse problem by inverting the system of equations. It is more compact written in matrix form, which is also the way you will find inverting linear systems of equations addressed in every introductory text on computational methods.
Nov
23
comment Hourglass on the Moon
"Since the force of sand hitting the bottom is only 1/6th as much on the moon, there can only be 1/6th as much sand in the air at any given time. " Doesn't follow. What is canceled is the loss of weight which is proportional to both $g$ and the mass flow rate. But the impact impulse is also proportional to both $g$ and the mass flow rate. I don't think that you can conclude anything from that.
Nov
23
comment If a neutrino has a rest frame, why can't a photon have a rest frame as well?
You are mixing classical wave descriptions with quantum descriptions and doing so incorrectly. In a medium photons are constantly interacting with atoms---being absorbed and re-emitted or undergoing coherent forward scattering. Either process is described by annihilation and creation operators so it it not sensible to talk of a single slower than light photon.
Nov
22
comment “Reality” of length contraction in SR
An observer doesn't have to change the universe, it is the very character of the universe that makes the the actual and correct measurement of lengths to change. It is built-in from the foundation up.
Nov
22
comment Energy resolution of LHC Electromagnetic Calorimeter
BTW -- the tag [accelerator-physics] is for the physics of accelerators, not physics done by taking the beams.
Nov
22
revised Energy resolution of LHC Electromagnetic Calorimeter
edited tags
Nov
22
answered Energy resolution of LHC Electromagnetic Calorimeter
Nov
22
comment Using GPS Satelites as dark matter detectors
I have to say that this question would be a lot better if you (1) exhibited the abstract here and (2) said a little bit about what you found clear and unclear in the abstract.
Nov
22
answered Is there a normal force on an object submerged in water?