PAllen's latest activity
-
PPAllen replied to the thread Undergrad Question about Parallel Transport.True, but that is just a recipe for constructing a pure Riemannian manifold, that happens to a submanifold. So it is actually covered in...
-
PPAllen replied to the thread Undergrad Question about Parallel Transport.No, not longest distance - you can deviate from a non minimal great circle path and make it longer - by any amount with squiggles. In...
-
PPAllen replied to the thread High School Thought Experiment: Behavior of shadow of object moving at speed c.Let’s keep in mind that the shadow would have to be 300 meters for a one microsecond delay between front and back. I don’t think the...
-
PPAllen replied to the thread High School Thought Experiment: Behavior of shadow of object moving at speed c.Consider the scenario for a slow moving object (close to a screen, far away flash bulb). What do you see? How is the fast moving object...
-
PPAllen replied to the thread High School Thought Experiment: Behavior of shadow of object moving at speed c.If you make the distant light source a flash bulb (at rest in screen frame), the fixes simultaneity. Then, you will definitely see a...
-
PPAllen reacted to acemoonbeam1's post in the thread Where Can Teachers Access and Collect Classic PSSC Physics Films from the 1960s? with
Like.
A number of teachers have been interested in collecting the black and white films that were part of the PSSC program in the 1960s. Many... -
PPAllen reacted to robphy's post in the thread Where Can Teachers Access and Collect Classic PSSC Physics Films from the 1960s? with Like.
Possibly useful: www.reddit.com/r/Physics/comments/162yl28/all_the_classic_pssc_physics_films_i_have_found/ and the last URL in that...
-
PPAllen reacted to euphoricrhino's post in the thread Graduate 3D rendering of electric field lines of a swiftly moving charge with Like.
Happy holidays folks. So I spent some time over the Thanksgiving holidays and developed a program that renders electric field lines of...
-
PPAllen replied to the thread High School More similar triangle problems.Regarding post #21, the formula given for area minimizing ##\theta## simplifies to ##\tan\theta=c/d##. The minimum area just becomes...
-
PPAllen replied to the thread High School More similar triangle problems.Ok, if we're bringing this back, I'll share my results. In reference to the diagram in the original post, let c be the segment labeled...
-
PPAllen replied to the thread Undergrad Physical Interpretation of Frame Field.So, FW transport along any curve will preserve all of these properties. Parallel transport will only preserve them along a geodesic. For...
-
PPAllen replied to the thread Undergrad Physical Interpretation of Frame Field.But that operation is typically called the exponential map (and is a completely rigorous construct)...
-
PPAllen replied to the thread Undergrad The quintessence as variable dark energy.That is an exceedingly narrow statement of the equivalence principle. The most commonly accepted meaning of strong equivalence principle...
-
PPAllen replied to the thread Undergrad The quintessence as variable dark energy.That's not an update. It shares exactly one author, and the topic is not the same. Obviously, there is some relationship, but that's...
-
PPAllen replied to the thread Undergrad The quintessence as variable dark energy.I wondered if anyone had ever treated voids using numerical relativity rather than more indirect approximations. I came across the...