Timeline for What is happening when magnetic field lines snap or break?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Jun 18, 2020 at 20:35 | comment | added | S. McGrew | That's correct. | |
| Jun 18, 2020 at 20:29 | comment | added | supercat | The field lines don't represent information, but rather places where it is observable. It is possible for an event to become observable in one place at a certain time, and then become observable a nanosecond later somewhere else a mile away, if the event itself occurred someplace that's roughly equidistant from both points. | |
| Jun 18, 2020 at 19:56 | comment | added | S. McGrew | I wouldn't say that. Information doesn't necessarily represent a physical entity, but it is subject to conservation laws and cannot be moved faster than the speed of light. | |
| Jun 18, 2020 at 19:05 | comment | added | supercat | I think it might be worth extending your answer to note that because the phase contours don't represent any physical entity, they are not bound by ordinary concepts of conservation or movement. | |
| Jun 18, 2020 at 17:47 | comment | added | S. McGrew | It depends a bit on what definition you choose for "magnetic field line". But you're right. For example, if two transverse magnetic waves are approaching each other from nearly opposite directions, there will be changes in the "magnetic potential contour lines" that move faster than the speed of light. The same can happen with light waves: phase contours can move faster than the speed of light because nothing physical is actually moving. | |
| Jun 18, 2020 at 17:28 | comment | added | supercat | That makes sense. But would it be fair to say that magnetic field lines can appear to move faster than the speed of light because they can move faster than the fields that are represented thereby (much as the spot projected by a rotating searchlight can travel at a rate much faster than any portion of the searchlight)? | |
| Jun 18, 2020 at 17:16 | comment | added | S. McGrew | Changes to magnetic fields always propagate at the speed of light. It's not crossing a magnitude threshold of potential that produces "field lines". Instead, it is variations in the arrangement of "peaks and valleys" in the magnitude of the potential that produce "field lines": the field lines correspond to the directions of the slopes between the "peaks and valleys". | |
| Jun 18, 2020 at 17:06 | comment | added | supercat | So does that mean that if two magnetic objects are moving relative to each other at near-relativistic speeds, changes to "magnetic potential" would propagate at the speed of light, and the field lines would "appear" between places where the instantaneous potential crosses certain thresholds? | |
| Jun 16, 2020 at 13:14 | history | answered | S. McGrew | CC BY-SA 4.0 |