Questions tagged [spacetime]
Within relativity (both special and general), changes of reference frames can change both the notions of space and of time, with one depending on the other as well. As a consequence, it is necessary to treat both concepts in a unified manner. Hence the term spacetime.
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Clarifying the role of symmetry in operator/state transformation rules
In Chapter 3 of his fairly classic text on quantum mechanics, Ballentine talks about the relationship between symmetries of physical space and corresponding transformations (via unitary operators, per ...
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What is the cardinality of intervals in space, and what is the cardinality of intervals in spacetime?
The interval $|(0, 1)| = |\mathbb{R}|$. I naively thought that one could treat intervals in space in kind, i.e., that the cardinality of any interval in space has the cardinality of the continuum. You'...
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Why are there two interior regions in this diagram?
Why are there two interior regions in this diagram? There seems to be two inner horizons, and two wormhole regions.
Where do the two such regions comes from? What determines which reason someone falls ...
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Where does the parallel universe in the Penrose diagram come from?
In this diagram, as well as our universe, you have a parallel universe.
Where does this come from? Is this just a artifact of the diagram, or is it predicted by the maths in some sort.
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Why should a Cauchy surface be closed?
A Cauchy surface is defined on any spacetime $M$ as a subset $S$ which is closed, achronal, and whose domain of dependence $D(S) = M$.
Why do we include the "closed" condition in the above ...
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Question on apparent super efficiency of the magnetic penrose process
Accordingly to this paper $[1]$, the efficiency of the so called Magnetic Penrose Process (MPP) is, for supermassive black holes of mass $M∼10^{10} M_{\odot}$ immersed in a magnetic field having $B∼10^...
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The value of speed of light in different regions of spacetime
This question of mine started shaping in my head first while I was looking for the most fundamental answer for the speed of light's value and its property of being the limit.
I have convinced myself ...
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If spacetime is discrete, would we observe continuous models to show non-rounding and non-truncation errors?
Typically, the ground truth is taken to be the continuous model. Numerical simulations are taken to be the approximation. These simulations deviate from the continuous model due to both a constant ...
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Could you take a point on the surface of the earth as the frame of reference in the Hafele-Keating experiment?
I was recently reading about the Hafele-Keating experiment and asking, how does time in the plane which has flow westwards could have passed faster than on the surface of the earth if the frame of ...
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Conceptualizing spacetime as static or evolving
I've been using this model to wrap my head around the concept of spacetime: https://www.youtube.com/watch?v=wrwgIjBUYVc
In the video you'll see an animation of an apparently dynamic and warping 3-...
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How exactly does Hawking radiation occur? [duplicate]
I understand some parts of the theory, I've read from here https://phys.libretexts.org/Bookshelves/Astronomy__Cosmology/Supplemental_Modules_(Astronomy_and_Cosmology)/Cosmology/Carlip/...
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Geometric definition absolute velocity in affine spaces
currently I am reading the following paper by Halvorson and Clifton (https://arxiv.org/abs/quant-ph/0103041) where they try to argue that localizable particles are inconsistent with relativistic ...
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