Activity for celtschk
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Answer | — |
A: What is inflation in cosmology? Inflation in cosmology refers to a phase of the early universe where the universe expanded extremely fast. And the universe expanding quite literally means the space getting bigger. As you noticed, cosmic inflation does not refer to just any expansion of the universe. The universe is still expandi... (more) |
— | over 3 years ago |
| Edit | Post #280801 |
Post edited: |
— | almost 4 years ago |
| Edit | Post #280801 | Initial revision | — | almost 4 years ago |
| Answer | — |
A: Would we need Alternating Current if superconducting wires existed? The major advantage of AC is that is can be easily transformed to different voltages. This is important because current transport is most efficient if the currents are low (because the losses are proportional to the square of the current), and this is achieved by making the voltage high for transmiss... (more) |
— | almost 4 years ago |
| Comment | Post #280385 |
I think that “seconds and light seconds” refers to convention (T), but what I actually proposed was convention (M), where you'd use seconds and meters just as in non-relativistic physics, and the light is purely in the metric. BTW, if you set all three of $\hbar$, $c$ and $G$ to $1$, what you actual... (more) |
— | almost 4 years ago |
| Edit | Post #280381 |
Post edited: |
— | almost 4 years ago |
| Edit | Post #280381 |
Post edited: |
— | almost 4 years ago |
| Edit | Post #280381 | Initial revision | — | almost 4 years ago |
| Question | — |
Unusual way to write spacetime coordinates/metric: Is there any downside? In special relativity, spacetime coordinates are normally given as $$(ct, x, y, z) \tag{S}$$ with the metric being either $$g = \operatorname{diag}(-1,1,1,1) \tag{+}$$ or $$g = \operatorname{diag}(1,-1,-1,-1) \tag{$-$}$$ depending on which sign convention the author prefers (the second one seem... (more) |
— | almost 4 years ago |
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