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61 Questions

Does a photon in vacuum have a rest frame?

Why is there a $\frac 1 2$ in $\frac 1 2 mv^2$?

Why isn't there a limit for a Euclidean rotation, as for a Minkowski rotation?

What experiments compete with BICEP 2, and when are their results expected?

Is Einstein's 1916 General Relativity paper a recommended way to start learning about the subject?

How does Dirac define the representative of $\{\langle\phi\frac{d}{dq}\}\psi\rangle = \langle\phi\{\frac{d}{dq}\psi\rangle\}$

Are the principles of space-time homogeneity and Isotropy independent of one another?

Is (0,0,0) an undefined vector?

Explanation for $E~$ not falling off at $1/r^2$ for infinite line and sheet charges?

Is the change in kinetic energy of a particle frame independent?

Is the electric field zero inside an ideal conductor carrying a current?

Should the eigenkets be weighted in $|P\rangle = \sum\limits_{r}|\xi^r\rangle$?

Proofs that every professional physicist should know

Is there a Newton's third law for the em field?

Is there a space-like equivalent of the Twin Paradox?

Calculate relativistic boost to COM frame from two arbitary velocities?

Why does a stationary force affect the conservation of momentum, but not the conservation of energy?

Can relativistic kinetic energy be derived from Newtonian kinetic energy?

Problems that Lagranges equations of the 1st kind can solve whereas the 2nd kind can't?

Does a spring's $k$ affect the acceleration of a coupled mass?

Must the varied paths in the action be physically possible?

What coordinate systems allows the magnitude of the basis vectors to change with position?

If time-like paths are geodesics, what physical principle applies to space-like intervals?

Why does Dirac write $\langle\xi'|\overline{f(\xi)} = \overline f(\xi ')\langle\xi'|$?

How does Dirac show that $\langle B|\bar{\bar{\alpha}}|P\rangle\;=\; \overline{\langle P|{\bar{\alpha}}|B\rangle}\;=\; \langle B|{\alpha}|P\rangle$?

Must the Lagrangian always be known for the Euler-Lagrange equations to be of any use?

Which main physics journals publish the main types of physics papers? [closed]

Can the Euler-Lagrange equations be derived from an infinitesimal Principle of Least Action?

Why isn't the force modelled which confines excess charge to remain inside a conductor?

Can the total energy-momentum of a rigidly accelerated extended body be expressed in terms of its mass, acceleration and velocity?