Timeline for Is radial time a solution of Einstein's equations?
Current License: CC BY-SA 4.0
9 events
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| Jun 30, 2021 at 23:20 | history | edited | Dale | CC BY-SA 4.0 |
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| Jun 30, 2021 at 23:17 | comment | added | Dale | @zooby if you did not say “flat” then you could have meant a metric like $ds^2=-dt^2 + t^2 dx^2 + t^2 dy^2 + t^2 dz^2$ which would be analogous to polar coordinates where $ds^2=dr^2 + r^2 d\theta^2$ except the radial coordinate is timelike and it is 4D. The problem is that this metric is not flat. Because you specified “flat” we are left with new coordinates on the Minkowski metric, as I described. It is a correct answer to the question you actually asked. | |
| Jun 30, 2021 at 20:34 | comment | added | Dale | @zooby in relativity “flat” means Minkowski spacetime. I have read your sentence many times and I honestly see no other way to interpret what you mean. You think your meaning is clear, but if it is not what I said then your meaning is in fact exceptionally unclear. Others agree | |
| Jun 30, 2021 at 20:29 | comment | added | user84158 | Read the first sentence of my question again. It's very very clear indeed. Thanks anyway. But I appreciate that maybe 'flat' in the context of SR might mean something different than flat in terms of just a 4D Euclideans space, in that it may presuppose that all lightcones align in a particular direction. | |
| Jun 30, 2021 at 3:17 | comment | added | Dale | @zooby Well, clearly your (clearly) is not as clear as you thought. Since you specified that it is flat that means that it is Minkowski spacetime with a different coordinate chart. There simply isn’t another way to read your question given that description. Both hulsey and Brick also understood it the same way I did. This answer was upvoted because it was a correct and careful answer to the question you actually asked. I am sorry to hear that you thought you had asked a different question. But at least the question you did ask was interesting to work through | |
| Jun 30, 2021 at 2:42 | comment | added | user84158 | No this is (cleaerly) not what I mean. I mean time flowing outwards from a point at the origin. Not sure why this answer got upvoted. It is simply a change of coordinates from normal Minkwoski spacetime where time flows along an cartesian axis. | |
| Jun 29, 2021 at 18:40 | history | edited | Dale | CC BY-SA 4.0 |
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| Jun 29, 2021 at 18:34 | history | edited | Dale | CC BY-SA 4.0 |
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| Jun 29, 2021 at 17:47 | history | answered | Dale | CC BY-SA 4.0 |