In Fermat's Principle of Least Time, how do we know that light is able to reach the end point?
61964
Is the principle of least action a boundary value or initial condition problem?
68058
Is it possible to determine the slit a photon went through in the double slit experiment by measuring its flight time?
57773
About the speed of light and gravity
155345
Can we use curved spacetime to measure the one-way speed of light?
67661
Is there an observable of time?
93598
Is it proven experimentally that the speed of causality (light) is the maximum speed?
63069
Why the Principle of Least Action?
64226
If traveling at the speed of lights stops time, why does it take light 8 minutes to reach Earth?
127383
Speed of light in general relativity
63067
How do particles "know" when to decay?
7618
What is the speed of light relative to?
84743
Why is light described by a null geodesic?
56065
How can the speed of light be a dimensionless constant?
22118
If all motion is relative, how does light have a finite speed?
88401
How is the amplitude of light related to number of photons?
81158
Light "diode" and 2nd law of thermodynamics
119953
What is the meaning of speed of light $c$ in $E=mc^2$?