# Recent content by Sonderval

1. ### I Mach-Zender-Interferometer with polarizers

@vanhees71 I'm not sure I understand. The beam splitters do not change polarization here, polarization comes into it only in situation 3 and 4 where I explicitly added the filters. That is why i simply added the appropriate H and V to the states in the 3rd equation. I totally agree that there is...
2. ### I Mach-Zender-Interferometer with polarizers

@vanhees71 I now tried to calculate things explicitly and believe my idea above to be incorrect. (Calculation follows below, I'd be very grateful for someone to check it.) However, I do see a problem with causality if my idea were correct: Image we set up the light source to send one photon per...
3. ### I Mach-Zender-Interferometer with polarizers

@charters Yupp, that's worrying me as well.
4. ### I Mach-Zender-Interferometer with polarizers

I have a question on how exactly polarizing filters would influence interference in a Mach-Zehnder interferometer. To explain, I'll show some configurations and what I would expect to happen - please tell me if I am incorrect anywhere. Here is the standard MZI configuration with no filters and...
5. ### B Phase shift in Mach-Zehnder interferometer

@vanhees71 Thanks. I was just confused because my sources never mentioned that there would be alternative ways of doing it - some used the asymmetric beam splitters, some used symmetric ones, but none mentioned that both exist.
6. ### B Phase shift in Mach-Zehnder interferometer

@Aidyan and Cthugha Funnily, the references you both provided on first sight again seemed to contradict each other - Zetie talking about 180° phase shift on reflection, Cthugha explaining that the shift is 90° But thanks to the reference by Henault, I finally understand it: There are symmetric...
7. ### B Phase shift in Mach-Zehnder interferometer

I'm confused by the phase shifts in a Mach-Zehnder interferometer because I keep finding two different explanations. One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the...
8. ### A Penrose diagram of black hole with a changing event horizon

@PeterDonis Thanks a lot. I assume the same is true for the case of the expanding hole. I find this somewhat surprising - the black hole expands and the photon moves "outwards" - but that's probably simply a consequence of using global coordinates. OTOH, it shows that Penrose diagrams are...
9. ### A Penrose diagram of black hole with a changing event horizon

Dear all, I have a question on Penrose diagrams. Consider a collapsing star that forms a black hole with a Schwarzschild radius normalized to 1. What happens in the Penrose diagram when additional matter falls in? I suspect the diagram then has to look like this : When the outer shell (second...
10. ### A Definition of bi-local measurement by Masanes et al.

@atyy Thanks. Yes, I suspect you're right and that this is what is more or less implied by the qualifier "local OPF", but at least to me it is not very clearly stated.
11. ### A Definition of bi-local measurement by Masanes et al.

Dear experts, I'm currently working my way through the paper Masanes, Galley, Müller, https://arxiv.org/abs/1811.11060. On page 3, they define what they call a bi-local measurement: If we have two systems a and b and we define an outcome probability function for some measurement f on system a...
12. ### I How does the speed of light affect clocks?

@Dale Absolutely great, that was exactly what I was looking for. PS: Would be great if you published/posted that calculation with the different constants somewhere.
13. ### I How does the speed of light affect clocks?

It seems I was phrasing things very badly. So if I understand things correctly, the correct way of stating things would be to look at all dimensionless constants and instead of talking about "changing c" I should talk about changing these constants. So instead of saying, "let's increase c by...
14. ### I How does the speed of light affect clocks?

Thanks, Ibix, but if I change c and none of the other constants (G, ħ...), does that not imply a change in the fine structure constant?
15. ### I How does the speed of light affect clocks?

If the speed of light would change in the universe without any other natural constant changing, would all clocks be affected in the same way by this? This is implied by Einstein in this paper on page 368 http://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstein-papers/1912_38_355-369.pdf...