298 reputation
19
bio website
location
age
visits member for 2 years, 7 months
seen Jul 7 '13 at 6:03

Mar
31
awarded  Student
Mar
31
comment Why is light described by a null geodesic?
+1 for coord transformation.
Mar
31
comment Do photons have acceleration?
This is not exactly acceleration of a photon. The photon is still following a null geodesic, so in the frame of the light, there is no acceleration. There might only appear to be some acceleration to another observer.
Mar
31
answered Question with Einstein notation
Mar
31
comment How to interpret the derivative in the momentum operator in quantum mechanics?
Never assume commutativity in QM unless you're sure of it.
Mar
31
answered At what point does a projectile leave a slingshot?
Mar
31
asked Why is light described by a null geodesic?
Mar
31
comment Why you need a graviton when you have the higgs boson?
In the linear approximation, GR predicts gravity waves, which can be described by gravitons. This explanation comes up independent of the Higgs Boson. The need for one doesn't really have any bearing on the other.
Mar
31
comment Is 4-velocity normalized to -1 even for non-geodesic timelike curves?
A geodesic, being defined as a curve whose tangent vector doesn't change along that curve (parallel transports its own tangent vector), will always return the same norm for that unchanged tangent vector. The same can't be said of other curves, because they don't necessarily have the same tangent vector at different points.
Mar
29
awarded  Citizen Patrol
Mar
29
answered Will tensile strength keep a cable from snapping indefinitely?
Mar
29
answered What is the difference between a moment and a couple?
Mar
29
answered A spinning bullet
Mar
29
comment More on the Feynman Path Integral Formula in Brian Cox' Lecture and its Consequences
Comment 3: Typo. Fixed it. That line was just multiplying both sides of the inequality by $\Delta t$.
Mar
29
awarded  Editor
Mar
29
comment More on the Feynman Path Integral Formula in Brian Cox' Lecture and its Consequences
Comment 2: Since you've divided both sides of the equation by the same number, they're still equal. You then say this new number is less than 1, because of the inequality you had before.
Mar
29
revised More on the Feynman Path Integral Formula in Brian Cox' Lecture and its Consequences
Typo in equation.
Mar
29
comment More on the Feynman Path Integral Formula in Brian Cox' Lecture and its Consequences
Comment 1: $m(\dfrac{\Delta x}{\Delta t})^2 \Delta t = m \dfrac{\Delta x^2}{\Delta t^2} \Delta t$. The $\Delta t$ on the left cancels out the $\Delta t$ under the line.
Mar
29
awarded  Supporter
Mar
29
answered The relativistic mechanics of a battery that is being charged and accelerated at the same time