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"head" in the name refers to the Mathematica concept. That was the first account I created. I kept the name.


2d
reviewed Edit Electric field calculation and its graph vs x
2d
revised Electric field calculation and its graph vs x
rendering math in latex
2d
answered Electrostatics and two electric charges
Apr
23
comment Is sound a Nambu-Goldstone mode?
Now you were probably looking at it from a field-theoretic point of view, where the fluid is represented by density, pressure, and velocity fields. In that case the ground state does have translational symmetry (zero velocity, uniform density and pressure), so there does not seem to be a broken symmetry, and so you would be led to say that sound is not a goldstone mode. That is an interesting point and I didn't think about that.
Apr
23
comment Is sound a Nambu-Goldstone mode?
I think you are saying that you do see how sound in solids is a goldstone mode, because there is a continuous symmetry that breaks and gives you a discrete symmetry. Now when I was talking about liquids and gases, I was referring to a particle based model. This model has a continuous symmetry that is broken, and the state with a broken symmetry has no remaining symmetry because particles in a liquid and gas are disordered.
Apr
22
revised Is sound a Nambu-Goldstone mode?
edited body
Apr
22
answered Is sound a Nambu-Goldstone mode?
Apr
14
comment Shouldn't the currents be time-continuous here?
I got slow and fast backwards in my explanation. The slow system with smaller resistance is more susceptible to changes in flux, and it is the one whose current increases as a result of the fast system's fast change in flux. I will fix my answer later.
Apr
14
answered Shouldn't the currents be time-continuous here?
Apr
13
comment How can static friction do work?
Without friction, the crate would remain still as the truck begins to move. (This is a simple consequence of newton's first law.) And so without friction, the crate would move left relative to the truck. Friction opposes this motion by providing a rightward force on the crate sufficient to keep the crate and truck moving at the same velocity.
Apr
10
comment Relativistic Momentum and Energy - Lorentz Transformations
I think their answer is wrong. The way you have it, you say $\gamma \to 2 \gamma^2$ from the boost. I think this is right. I am pretty sure that they just multiplied by an extra factor of $\gamma$.
Apr
10
answered How can static friction do work?
Mar
26
answered Unit consistency
Mar
21
comment Relationship bewtween the principle of Galilean Relativity and absolute time
I don't think I understand the question. Are you asking if "invariance of laws of physics under transforming between inertial frames" $\implies$ "absolute time"? This is of course false, with a counter-example being special relativity. Otherwise could you explain what the principle is you are referring to in the first sentence of your second paragraph (v1)?
Mar
21
reviewed Approve Boundary Layer in aerofoil
Mar
21
reviewed Approve Can bulk modulus ever be negative? Can somebody illustrate with an example!
Mar
2
reviewed Approve Why isn't the ISS electrically charged?
Feb
27
comment Derivative of the magnetic field to the vector potential
@Nick See the appendix that I added. The factor of two comes from the fact that you are differentiating $B_jB^j$, so when you do that product rule you get two terms: one for differentiating the first $B$, one for the second. These two terms are equal and so when they add they give you a factor of two.
Feb
27
revised Derivative of the magnetic field to the vector potential
added 5607 characters in body
Feb
27
awarded  Enlightened