17,845 reputation
13393
bio website lightandmatter.com
location Fullerton, California
age
visits member for 2 years, 9 months
seen Mar 30 at 19:12

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.


Sep
1
answered Are electrons just incompletely evaporated black holes?
Sep
1
answered Does spacetime in general relativity contain holes?
Sep
1
comment Does the (relativistic) mass change? Why?
Certainly Einstein's 1905 postulates (which are kinematical, not dynamical) were motivated by experiment. That doesn't mean that every fact in the theory of SR can only be proved by direct reference to experiment.
Sep
1
comment Does the (relativistic) mass change? Why?
This is helpful because it points out to the OP that his/her question was phrased in obsolete terminology. However, it doesn't fundamentally address the question. The question is asking for why there is a factor of $\gamma$ involved, regardless of whether or not we group the factors of $p=(m\gamma)v$ and refer to $m\gamma$ as mass.
Sep
1
comment Does the (relativistic) mass change? Why?
Now there is no other answer to "why", then "because that is the way nature behaves". Not true. The relativistic behavior of inertia and momentum follows logically from the postulates of special relativity.
Sep
1
revised Does the (relativistic) mass change? Why?
added 176 characters in body
Sep
1
answered Does the (relativistic) mass change? Why?
Sep
1
comment Does the (relativistic) mass change? Why?
The OP knows that it follows from the postulates of SR, but wants to know how. This doesn't address the question.
Sep
1
comment Why does an object with higher speed gain more (relativistic) mass?
The OP asked a "why" question. This answer simply starts by asserting the result.
Sep
1
comment Why does an object with higher speed gain more (relativistic) mass?
[...] The middle portion of the answer is correct but is only a description of what happens relativistically. The question was a "why" question. Lorentz transformations dominate the scale at these accelerated energies and you end up with a particle that shrinks to zero. Is this referring to length contraction? Why is that relevant? Another way of saying this is that if you accelerate an object that has a non zero rest mass towards the speed of light, what you end up with is black hole traveling awfully darn fast. No, this is not true.
Sep
1
comment Why does an object with higher speed gain more (relativistic) mass?
Welcome to physics.SE! Sorry to have to greet you with negative comments, but -- fermions have a non zero rest mass by way of Higgs field interaction. This is not really true. Composite particles have mass due to their internal fields. Even for fundamental particles it's not so simple: physics.stackexchange.com/questions/3037/… . Very little of the mass of ordinary matter comes from the Higgs mechanism, and in any case this is not relevant to the question. [...]
Sep
1
comment Why does an object with higher speed gain more (relativistic) mass?
possible duplicate of Why does the (relativistic) mass change & why?
Sep
1
comment Does the (relativistic) mass change? Why?
duplicated by physics.stackexchange.com/q/71772
Sep
1
comment If photons have no mass, how can they have momentum?
In the 19th century it was already known that light can collide with matter A beam of light can make a small wheel, in vacuum, rotating No, this is a historical misconception. See the WP article "Crookes radiometer." In my opinion it is not necessary to evoke the theory of relativity or quantum physiscs to explain how light can have momentum but no mass You invoke the relation $q=L/c$, which is a relativistic relation.
Sep
1
comment If you flew into a black hole
@ChrisWhite: Oops, thanks for the correction. Obviously that should have been "singularity."
Sep
1
revised If you flew into a black hole
deleted 2 characters in body
Sep
1
comment Effects of magnetic fields on our bodies
The title and the first two sentences seem to be one question. The final two sentences seem to be a completely different question, which you might want to ask separately. Re your personal experience, nobody can tell you anything unless you can give us a number for the intensity of the fields you were exposed to.
Sep
1
comment Why are magnetic field lines perpendicular to the surface of a ferromagnetic material?
@Cheeku: Again, it would be helpful if you would edit your question to briefly present the argument you're talking about. Otherwise it's not clear, at least to me, what feature of the argument you're asking about.
Sep
1
comment Why are magnetic field lines perpendicular to the surface of a ferromagnetic material?
Are you specifically interested in ferromagnetism, not just high permeability?
Sep
1
comment Why are magnetic field lines perpendicular to the surface of a ferromagnetic material?
Probably missing something, so I'll comment rather than answering. Could you outline the argument you've seen that requires zero magnetization at the surface? The argument I'm familiar with is as follows. Faraday's law says that in the static case when there are no macroscopic currents present, the curl of H is zero. This requires the parallel component of H to be continuous across the surface of a permeable material, which means that $B_{\parallel}=\mu H_{\parallel}$ has a discontinuity. This means that whatever the direction of B inside the surface, it has to be small outside the surface.