cianfa72's latest activity
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cianfa72 replied to the thread Undergrad About the notion of non-standard inertial frame.Can we extend the construction given in #11 to any spacetime, e.g. even to non maximally symmetric spacetimes ? I'm not positive about... -
cianfa72 replied to the thread Undergrad About the notion of non-standard inertial frame.So for instance in Minkowski spacetime that has 10 independent symmetries, pick 4 independent translational KVFs (they define a frame...
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cianfa72 replied to the thread Undergrad About the notion of non-standard inertial frame.Ok, since assuming isotropic laws includes the light propagation process. Isotropy forces Einstein synchronization, i.e. spacelike...
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cianfa72 reacted to PAllen's post in the thread Undergrad About the notion of non-standard inertial frame with
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Ok. That would rule out e.g. the coordinate transform ##x'=log(x)## because an object with no proper acceleration moving in the x'... -
cianfa72 replied to the thread Undergrad About the notion of non-standard inertial frame.Ok, you mean that the requirement that zero proper acceleration has constant coordinate speed allows for spatial planes (spacelike...
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cianfa72 posted the thread Undergrad About the notion of non-standard inertial frame in Special and General Relativity.I had a DM with @PAllen about the notion of non-standard inertial frame. Let's consider a (global) inertial frame in the context of...
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cianfa72 reacted to PAllen's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
Let's stop right here. We will not get far by insisting that "we all must agree that 2 + 2 = 5". A given flash bulb (for example) has...
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cianfa72 reacted to A.T.'s post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
It's not symerical, because the light source is at rest in one frame, but not the other. Motion relative to some random light source...
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cianfa72 replied to the thread Undergrad The Einstein Clock aka Light Clock.Yes sorry, only later I realized the point was about isotropy of light intensity and not light propagation process (speed).
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cianfa72 reacted to Dale's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
Consider a dipole antenna that emits a brief pulse. The emitted radiation is not isotropic in any frame. But the shape of the wavefront...
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cianfa72 replied to the thread Undergrad The Einstein Clock aka Light Clock.Why assume the isotropy of light in this frame (i.e. in the frame where the horizontal blue plane has equation t= const). The light cone...
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cianfa72 reacted to Ibix's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
On reflection (sorry) I'm not sure this is correct, and need to do a bit of maths. It is definitely true that if the source emits a...
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cianfa72 replied to the thread Undergrad Question about Parallel Transport.As far as I can tell, the parallel transport on the round sphere, when considering it embedded in 3D ambient euclidean space, works as...
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cianfa72 replied to the thread Undergrad Question about Parallel Transport.Ah ok. So suppose to start with the turret's gun pointing in one given direction. Then, along the path being taken from the tunk hull on...
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cianfa72 reacted to A.T.'s post in the thread Undergrad Question about Parallel Transport with Like.
As I said in post #28, constraining a standard gyroscope axis to stay tangential to the surface won't work here. An actual 2D gyroscope...