33,321 reputation
345109
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 9 months
seen 1 hour 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.


10h
comment Angular and Linear Acceleration
This is one of those places where looking at the units of the quantities could be of a lot of help to you.... Of course once you've done that you have to check if that quantity is $= g$ or just $\propto g$.
11h
comment How can light travel at speed of light?
Note that (1) any other massless particle must also travel at $c$ and (2) that light does not "reach" $c$, it simply has that speed.
11h
comment How to convert 1atm to kj/m3
All commenters should remember to "Be nice."
14h
comment Why is there a controversy on whether mass increases with speed?
"In a book from the Roosevelt administration [...]" ::chortle::
14h
comment Why is there a controversy on whether mass increases with speed?
The whole point of the question is that there are two camps on the usage of the word "mass" You've related the description used by the camp that speaks of "relativistic mass", but totally ignored the (rather larger among working rather than teaching physicists) camp that assigns the symbol $m$ to the invariant mass and don't give any name to $\gamma m$ at all. In other words you haven't even shown that you understood the question much less addressed it.
14h
comment How cold would a bowling ball near absolute zero make a room?
Er ... it (the ball) would warm up? I mean, your room would get chilly for a few minutes, but nothing catastrophic is going to happen unless you insist on cuddling up to it and that will hurt enough to convince you not to.
14h
comment What are the mechanics by which Time Dilation and Length Contraction occur?
This answer is both a link-only job and addresses something other than the actual question.
14h
comment Can we build large spaceships?
Effectively a duplicate of this posters earlier questions: physics.stackexchange.com/questions/133413/… . The answer remains that there is nothing preventing us from constructing large structures in space except (1) the cost of getting materials and personnel into orbit and (2) a total lack of experience in running large projects in microgee (we actually have a little bit of experience building things there).
15h
comment Alignment of a triaxial accelerometer
Key meta questions here include: meta.physics.stackexchange.com/q/4535/520 meta.physics.stackexchange.com/q/2948 and perhaps meta.physics.stackexchange.com/q/5553/520 . The upshot is that the context matters. If Branny would like to say a few words about his (or her) need for this it might help resolve the issue.
21h
comment Resistors in para and series circuit, finding volt
I've removed a bunch of comments as being noise now that the participants have had time to see them.
21h
comment Dark matter a medium for light propagation
In the usual understanding the field does permeate all space, but it may have value zero in much of it, indicating that there is "no electric field" in the language used in introductory courses.
21h
comment As the universe expands, the wavelengths of photons are stretched, and energy is lost. What about electrons?
The notion of "free propagation" here is the same as it's meaning in ordinary mechanics or quantum mechanics: it means that we can neglect the forces acting on the particle. Nothing mysterious at all. The changing of the scale factor is not a force in the conventional sense and does not interfere with understanding the term in the usual way.
1d
awarded  energy
1d
comment In a radioactive Bose-Einstein condensate, would all the atoms disintegrate simultaneously?
@SebastianHenckel You have no reason to assume that merely because the bulk motion of the atoms are coherent the internal states of their nuclei are also coherent; these phenomena are decoupled and happen at very different energy scales.
1d
comment Is work is equal to $mv^2$ (without $\frac{1}{2}$)?
You have (almost) rediscovered the Work-energy Theorem. Done right you get $W = \Delta \left( \mathrm{KE} \right)$. Your problems are (1) assuming you start from rest which is not true in general and (2) neglecting to use the average velocity when substituting for time (a problem that goes away if you do this with calculus).
1d
comment Why is there a controversy on whether mass increases with speed?
You emphatically don't need to enter any particular frame to get the (rest) mass because it is a relativistic invariant and is defined perfectly well in any frame: $m = \sqrt{E^2 - \mathbf{p}^2}$ (in $c = 1$ units and with a $\mathrm{Tr} = -2$ metric). It's that property of invariance which makes this definition so useful.
1d
comment Why is there a controversy on whether mass increases with speed?
There is no controversy whatsoever on physics, only on the best way to assign vocabulary. Parties on both side of the divide (such as it is) can agree on the results of any calculation.
1d
comment Electromagnetic field and continuous and differentiable vector fields
As in mechanics you make a continuum approximation. This is discussed at some point in every good text. The better ones also discuss the situation in which it breaks down.
1d
comment Solenoid pull force & Velocity calculation
Yes, you were. So go into the edit history (click the time above the editor's icon (currently me)), scroll down to the revision where things were right and hit "revert".
1d
comment What experiment would prove string theory?
@TerryBollinger "Where is the proof that a theory based on strings is the only complex formulation capable of encompassing known physics?" I don't think there is one at this point, but as I understand it the string guys have shown that any theory based on the group structures of the existing symmetries must be homomorphic with string theory which I guess says that as long as we're sticking with groups we may as well use their work.