cianfa72's latest activity
-
cianfa72 replied to the thread I How do non-diagonal indices of a metric allow for local flatness?.In Anderson coordinates the expression of the flat spacetime metric ##ds^2## includes mixed term in ##\kappa dtdx##. For ##\kappa=0##... -
cianfa72 reacted to Dale's post in the thread I How do non-diagonal indices of a metric allow for local flatness? with
Like.
Yes. Also, any four-velocity is a 4D tangent vector to a worldline. So that vector is the same vector in different frames, although its... -
cianfa72 replied to the thread I How do non-diagonal indices of a metric allow for local flatness?.Ah ok, I think what I put in bold is the key point. What is actually invariant are the light cones and therefore the light's velocity as...
-
cianfa72 reacted to Dale's post in the thread I How do non-diagonal indices of a metric allow for local flatness? with Like.
As @PeterDonis mentioned also the coordinate two way speed of light can vary in non-inertial charts. Although that does also depend on...
-
cianfa72 replied to the thread I How do non-diagonal indices of a metric allow for local flatness?.I think you actually mean the one-way speed of light (OWSOL) is only invariant in the standard inertial coordinates (assuming of course...
-
cianfa72 reacted to Ibix's post in the thread I Conventionality of the One-Way Speed of Light with
Agree.
It's not necessarily the one-way speed, but it is necessarily the two-way speed of light. What your maths tells you, in short, is that... -
cianfa72 reacted to renormalize's post in the thread I Transformation for Lemaitre coordinates with Like.
Yes you can! Inspired by https://en.wikipedia.org/wiki/Lema%C3%AEtre_coordinates, note that your two...
-
cianfa72 replied to the thread I 2-sphere intrinsic definition by gluing disks' boundaries.Of course the relevant gluing map glues "corresponding points" on disks ' boundary (e.g. point ##(1,0)## of ##D_{+}## is glued with...
-
cianfa72 reacted to lavinia's post in the thread I 2-sphere intrinsic definition by gluing disks' boundaries with Like.
@cianfa72 Your thoughts brought to mind a few considerations that I thought would be of interest to you. You start out by saying that...
-
cianfa72 reacted to PeroK's post in the thread I Validity of identical eigenfunction of commutating operators with Like.
All Hermitian operators commute with ##I##. And every vector is an eigenvector of ##I##. This is wrong. There must be a common...
-
cianfa72 replied to the thread Announcement Please welcome berkeman as PF Admin.Very good, congratulations !
-
cianfa72 reacted to fresh_42's post in the thread I 2-sphere intrinsic definition by gluing disks' boundaries with Like.
The quotient building is the identification of certain points in ##D_+## with certain points in ##D_-.## You have to show that these...
-
cianfa72 replied to the thread I 2-sphere intrinsic definition by gluing disks' boundaries.Yes of course. From the definition of ##f## given in #2 it takes the same value (##f=0##) on the pair of points in ##D_+## and ##D_-##...
-
cianfa72 replied to the thread I 2-sphere intrinsic definition by gluing disks' boundaries.Ok, coming back to the OP, just to be clear, what is a bijective continuos map is the function ##\tilde f## resulting by passing ##f##...
-
cianfa72 replied to the thread I 2-sphere intrinsic definition by gluing disks' boundaries.I was thinking as follows: call ##D_{+}## the disk of radius 1 centered at the origin of ##\mathbb R^2## and ##D_{-}## the disk of...