Timeline for In relativity, is the fourth spacetime dimension spatial or nonspatial?
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6 events
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| Jul 10, 2023 at 20:47 | comment | added | foolishmuse | @naturallyInconsistent Can you lay that out a bit more clearly, mathematically? Something like time dilation = space dilation^2 Keep in mind that it does not take very much time dilation to create gravity. It takes 30,000 years for a one second difference between sea level and the top of Mount Everest. | |
| Jul 10, 2023 at 17:16 | vote | accept | Glycoversi | ||
| Jul 8, 2023 at 4:58 | comment | added | naturallyInconsistent | Actually, it is mostly that time part is curving, not space. Otherwise, we would have observed a lot of space curvature in the context of astronomy just from Earth's own gravitational pull. Instead, it is a lot of curvature in the time dimension and a little bit in the space parts, where the latter is really just there because you cannot curve time alone, but rather the only spacetime must be curved simultaneously, to satisfy some mathematical requirements. @MaximalIdeal it is thus not independent. | |
| Jul 7, 2023 at 18:43 | comment | added | foolishmuse | @MaximalIdeal the metric is a mathematical model. In the model you can vary the 3 spatial directions in any length or amount that you want, and you can also vary the time dimension in any length or direction that you want. But I don't think that this variability reflects reality. Directions X,Y and Z all grow proportionality to each other, and time also does so. | |
| Jul 7, 2023 at 18:28 | comment | added | MaximusIdeal | "space itself is dilated and because of this, time is also dilated" Not to nitpick, but my understanding is that spatial dilation and time dilation can vary independently from one another (unless you add more constraints). In the metric $ds^{2} = -Adt^{2} + Bdx^2 + \cdots$, factors $A$ and $B$ can vary independently. Now in GR, Einstein's equation puts constraints on how $A$ and $B$ can vary, but that's not the same reasoning as what you wrote. Apart from that, everything you wrote seems valid and sound. | |
| Jul 7, 2023 at 17:54 | history | answered | foolishmuse | CC BY-SA 4.0 |