Timeline for On intersection of null geodesics
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
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| Oct 25 at 14:04 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jun 27 at 14:01 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Feb 28 at 13:06 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jan 30 at 2:33 | review | Close votes | |||
| Feb 5 at 3:07 | |||||
| Jan 30 at 2:18 | comment | added | Willie Wong | As Ettore Minguzzi pointed out in the previous comment, the set-up is ill-defined and the question unanswerable. Since the OP has not provided additional clarification, I am voting to close this question. | |
| Jan 29 at 4:06 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Dec 30, 2023 at 3:15 | answer | added | Anton Petrunin | timeline score: 0 | |
| Feb 19, 2021 at 10:51 | comment | added | Ettore Minguzzi | The splitting is not canonical, there are many such splittings, so it seems that the transverse geodesics that you are considering are ill defined unless you introduce a privileged timelike vector field. | |
| Feb 18, 2021 at 2:22 | comment | added | Ali | Yes, the geodesics should be transverse to the cone. I think this is all well-defined by global hyperbolicity, since spacetime has a global splitting of the form $g(t,x)= -\beta(t,x) dt^2+ g_0(t,x)$. | |
| Feb 18, 2021 at 1:08 | comment | added | Willie Wong | In fact, I don't understand your comment at all! Given a $C^-(p)$ the only way I know where you can construct a "dual null vector" for $q\in C^-(p)$ is if you prescribe a priori a space-like foliation of $C^-(p)$, whereby there is a canonical null direction transverse to $C^-(p)$ that is orthogonal to the space-like leave through $q$. But this is not as simple as what you claimed in your comment. | |
| Feb 18, 2021 at 1:06 | comment | added | Willie Wong | wait, I thought I understood your question, but now I am confused. Are $\gamma_{q_1}$ and $\gamma_{q_2}$ supposed to be transverse to $C^-(p)$ or not? The way the question text itself is written, I would've interpreted $\gamma_{q_1}$ as the null geodesic joining $p$ to $q_1$. But your comment suggest something else. | |
| Feb 18, 2021 at 0:46 | comment | added | Ali | I should clarify that of course. Here, due to splitting of spacetime, you can always associate to a null vector $v=c\partial_t+\nu$ a canonical dual null vector $\tilde{v}=-c\partial_t+\nu$. The vector $\tilde{v}$ is what I mean by the (pseudo)-normal. | |
| Feb 17, 2021 at 18:52 | history | asked | Ali | CC BY-SA 4.0 |