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HNQ
4:48 AM
1
Q: Can you actually stand inside a rainbow? I see people claiming you can

JakeI have been thinking about this for ages and it has been driving me crazy. I was convinced that rainbows are always complete circles that appear to be arcs because they cross the horizon. Then, I saw videos like this, where the rainbow appears to reach the ground and continues to move away until ...

 
 
8 hours later…
HNQ
12:33 PM
2
Q: Is it possible to derive the Weyl tensor from the Ricci tensor or Ricci scalar? If so, how?

Jungwoon SongI understand that the Ricci tensor is derived from the Riemann tensor, but I know that the Weyl tensor is also derived from the Riemann tensor. So is it possible to calculate the Weyl tensor from the Ricci tensor or Ricci scalar and if so how?

 
 
6 hours later…
HNQ
6:34 PM
1
Q: Pushing something on a theoretically frictionless surface

HectorLet's say, if i apply a specific force on an object on a theoretically frictionless surface, will it move at constant velocity forever? If i apply newton 2nd law, F = ma, there will be a certain acceleration, so will the object move at constant velocity or a increasing velocity(constant accelerat...

 
 
1 hour later…
HNQ
7:51 PM
2
Q: Lossless beam splitter relations

DarkeninWikipedia says that for a beam splitter $$\begin{bmatrix}E_{c}\\ E_{d} \end{bmatrix}=\begin{bmatrix}r_{ac} & t_{bc}\\ t_{ad} & r_{bd} \end{bmatrix}\begin{bmatrix}E_{a}\\ E_{b} \end{bmatrix}$$ the demand $\left|E_{c}\right|^{2}+\left|E_{d}\right|^{2}=\left|E_{a}\right|^{2}+\left|E_{b}\right|^{2}$ ...

 

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