PeterDonis's latest activity
-
PeterDonis replied to the thread Undergrad The Einstein Clock aka Light Clock.@DmitryS you have made the same error multiple times now, and have persisted in it despite repeated corrections. Enough is enough. The... -
PeterDonis reacted to Dale's post in the thread Undergrad The Einstein Clock aka Light Clock with
Like.
Yes, there is a problem. The problem is here: That is false. The source of light is current and charge densities, as described by... -
PeterDonis posted the thread Graduate Strong Progenitor Age Bias in Supernova Cosmology in Cosmology.The thread title is the first part of the title of a paper published just today [1]. Here is the abstract: [1]...
-
PeterDonis replied to the thread Undergrad Does a person's mass affect time?.The OP was asking about an individual person's mass affecting their perception of time. That is not only "not noticeable in common...
-
PeterDonis replied to the thread Undergrad Does a person's mass affect time?.This is very vague. The correct statement is that the curvature of spacetime is affected by the presence of stress-energy, via the...
-
PeterDonis replied to the thread Undergrad About the notion of non-standard inertial frame.You can do this, but you can't do it by only transforming the spatial coordinates from a standard inertial frame. In fact, the simplest...
-
PeterDonis replied to the thread Undergrad Integration of energy-momentum pseudotensor for Kerr BH.This is not a correct claim. You need to be very, very careful interpreting anything involving pseudotensors. The Schwarzschild BH is...
-
PeterDonis replied to the thread Undergrad Integration of energy-momentum pseudotensor for Kerr BH.Equations in images are not permitted here. Please use the PF LaTeX feature.
-
PeterDonis reacted to PAllen's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
Maybe it would help to imagine two flash bulbs, one in motion relative to the other. They both flash when one just passes the other. In...
-
PeterDonis reacted to PeroK's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
The light clock is really very simple. If you accept the invariance of the speed of light, then time dilation, length contraction and...
-
PeterDonis 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...
-
PeterDonis replied to the thread Undergrad The Einstein Clock aka Light Clock.What else would be involved? No, they don't. The source can only be motionless with respect to one of them. Until you fix this...
-
PeterDonis reacted to Dale's post in the thread Undergrad The Einstein Clock aka Light Clock with Like.
Also, note that @Ibix said that the point is motionless, not that the source is motionless when it is at that point.
-
PeterDonis replied to the thread Undergrad Integration of energy-momentum pseudotensor for Kerr BH.How? This is not quite as straightforward as you seem to think. I have no idea unless you explain how you did the Schwarzschild...
-
PeterDonis replied to the thread Undergrad The Einstein Clock aka Light Clock.No, you don't. The light source is not a point. It's a worldline--the path through spacetime of an object (whatever object emits the...