Recent comments from SciRate

malik matwi May 27 2016 20:48 UTC

I have a question, relates to:
However, since the non-gravitational physics has been accurately explained by the principles of quantum mechanics, it seems necessary that General Relativity is merged with quantum mechanics.
but the quantum principles at first emerged from boundary conditions in th

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Jonathan Oppenehim May 27 2016 03:46 UTC

Well, one answer to that question is that a memory recording (or recording of a preparation) is so redundantly encoded in the environment, that it is practically impossible to undo it. Of course, one could theoretically undo it, by performing the operation on all the copies of the information, which

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Renato Renner May 25 2016 11:32 UTC

Note that A and W carry out their measurements at the end of the experiment (i.e., there is no further measurement). The resulting entanglement is hence irrelevant.

Renato Renner May 25 2016 11:23 UTC

Interesting question. But doesn't “recording a value” mean that we prepare a system (the “memory system”) in a certain state and then assume that it will stay in that state? So, unless we make a distinction between “memory systems” and “normal quantum systems”, the potential problem you are mentioni

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Jonathan Oppenehim May 25 2016 00:34 UTC

Thanks. So, taking the example of a quantum contextuality proof where I undo one of the measurements, is it fair to say that the distinction you are making with your experiment, is that the thing which is undone is a preparation and not a measurement? Is it not just as problematic to ascribe values

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Ninnat Dangniam May 24 2016 07:29 UTC

Thank you for clearing that up. But wouldn't the entanglement with A and W creates an external record of the states of F1 and F2' labs and bring me back to the same problem? That is, starting from $ |T\rangle |\downarrow \rangle |\text{ok} \rangle_{AW} $, to infer $ |T\rangle |\rightarrow \rangle |\

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Renato Renner May 24 2016 05:52 UTC

Note that states of the form $|\downarrow\rangle_{F2}$ are meant to be states of the entire lab of experimenter F2. (I am sorry if this was unclear.) Hence, in the particular case you mention, the electron is automatically included in the description because it is within F2's lab. But you are of cou

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Ninnat Dangniam May 24 2016 00:27 UTC

Hi. I'm also worried about erasing a measurement record but in the inferential step (26)=>(35).

The gist of the argument seems to lie entirely in these two terms of the Hardy state (ignoring the normalization): $$ |T\rangle |\uparrow \rangle + |T\rangle |\downarrow \rangle = |T\rangle |\rightarrow

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Renato Renner May 23 2016 19:41 UTC

The crucial fact to notice is that the derivation of Eq. 25 relies entirely on standard quantum mechanics (applied from the viewpoint of F1): If a system is prepared in a state $\psi$ and subsequently evolves according to a unitary $U$ then its state will be $U \psi$ (and a measurement will give an

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Jonathan Oppenehim May 23 2016 02:19 UTC

Yes, exactly -- thanks for the prompt response. Lluis Masanes observed further that by invoking special relativity, one can have different observers who would make different statements about actual measurement records that would be consistent in their reference frame, but if they tried to get togeth

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malik matwi May 22 2016 22:42 UTC

at first I tried to satisfy the chiral symmetry, in that place, I thought that the chiral symmetry breaking is due to vacuum classical polarization, and this problem is solved by dual behavior of fields, some of these notes are in the first paper http://iiste.org/Journals/index.php/APTA/article/view

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Renato Renner May 22 2016 20:39 UTC

Regarding your question about the measurement records: You are right that the values r, z, x, and w are not at the same time available. But r and z, for instance, can be accessed simultaneously (at time n:20), which justifies the statements involving only these two (e.g., our Eq. 26). The same holds

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Jonathan Oppenehim May 19 2016 22:00 UTC

Hi Renato, yours and Daneila's paper has generated a lot of discussion, and today, Will Matthews presented it to our group at UCL. A question: in deriving the contradiction are you not ascribing results to measurements which are later undone/erased? So at the end of the experiment, there is no measu

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Bang-Hai Wang May 19 2016 15:07 UTC

Hi Marco,

Thank you very much for taking the time to reply to my message! I really appreciate it! I think I fully understand what you mean until now. We should state the notion of cone and the relation between our results and the notion of cone. We will try to give an objective and precise expres

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Travis Scholten May 18 2016 20:24 UTC

Great figures! Looking forward to reading this one.

malik matwi May 18 2016 18:19 UTC

at first I tried to remove x1=x2 from the propagation

https://www.docdroid.net/TYzB01L/the-time-stop-in-the-quantum-fields-fluctuation.pdf.html

the propagation modification is legal according to remove x1=x2
to satisfy the symmetries I related that modification to dual fields behavior, as I think

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Marco Piani May 18 2016 11:38 UTC

Hi Bang-Hai,

thank you for your message, and my apologies: I have intermittent internet connection and a decently long reply of mine got lost because of that :-( Unfortunately I do not have the time to rewrite it in full.

What I meant is that people have known for quite some time about the du

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Bang-Hai Wang May 16 2016 18:51 UTC

Hi Marco,

Right! Thank you for your mathematical explanations and clarifications, I really appreciate it! Could we add your pointing to our new version?

Frankly, we try to clarify more notions and results and connections among them, physically, not mathematically (It is also the reason that we ha

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Marco Piani May 16 2016 13:34 UTC

I am not sure where this goes (I have only skimmed through the first part of the paper), but what the author seems to find unexpected is the notion of cone dual to a cone, and the fact that the cone of positive operators is self-dual, while entanglement witnesses are dual to separable operators, etc

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Joshua Lockhart May 12 2016 12:14 UTC

Some of the figures in your bound entanglement paper look spookily like some of our graphs! Thanks for highlighting these connections Māris, I appreciate it.

Māris Ozols May 12 2016 07:07 UTC

You introduce some very interesting concepts in this paper! I just wanted to point out some connections that might be interesting to explore.

**Hamiltonian complexity**

The density matrix in your eq. (2) looks exactly like 2-local Hamiltonian that encodes classical computation in its ground state

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Jochen Szangolies May 06 2016 15:37 UTC

Granted that it would yield a different story if A were to perform the interference experiment instead, but it's certainly a story quantum mechanics allows us to tell---and that story depends on $z$ being indefinite in value. And one could also tell a combined story, in which A randomly chooses whet

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Renato Renner May 05 2016 15:27 UTC

Since I can imagine two reasons for why you think that a statement such as $(\text{n:20}, *, z, *) \in s^A$ could be problematic, let me make two remarks that may clarify this point. The first is that the experiment A (the one that experimenter A wants to analyse) consists *by definition* of a measu

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Ioannis Kogias May 05 2016 11:31 UTC

Makes sense! Thank you for all the explanations and clarifications, I really appreciate it. Cheers

gae spedalieri May 03 2016 15:33 UTC

This is a nice result!

Jochen Szangolies May 03 2016 11:14 UTC

Thank you for taking the time to answer my question, I really appreciate it. However, I'm sorry but unfortunately, I'm still not quite sure I get it---basically, I don't understand how, e.g., $(n: 20,\psi_C,z,*)$ can be a 'plot point' of A's story. I mean, during the time interval $(n:20,n:30)$ (i.e

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Renato Renner May 03 2016 08:12 UTC

Yes, you have understood correctly, I would say. One intuitive way to think about this is to “halt” the experiment already at time t = n:30, after A has seen outcome x, and ask yourself what statements A can now make. At this time, the measurement of z has been carried out, so A (although he hasn’t

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Renato Renner May 03 2016 08:04 UTC

The question whether two statements, S1 and S2, are "contradictory" is, in my opinion, independent of whether they are experimentally testable. Let me propose another example to illustrate this. A theory about atomic physics may allow us to derive the two statements S1 = “If the Coulomb constant was

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Cristi Stoica May 02 2016 21:46 UTC

Hi Renato. After reading the paper and following our discussion, I have some comments. Being large, I put them on my blog:
[http://www.unitaryflow.com/2016/05/are-single-world-interpretations-of-quantum-theory-inconsistent.html][1]

[1]: http://www.unitaryflow.com/2016/05/are-single-world-int

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Ioannis Kogias May 02 2016 13:45 UTC

I guess what I am really asking/wondering is whether it's legitimate to characterize theories as "inconsistent" in this context, as this term is commonly used to characterize theories that are self-contradictory when it comes to observable quantities. Otherwise, how would it be possible to have an

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Jochen Szangolies May 02 2016 11:00 UTC

Interesting paper. I'm not yet quite done digesting it, but one thing that trips me up is that from the point of view of A, before they do any measurement, it seems the whole system of F1 + F2 should be described by some superposition; in particular, the outcome of F2's measurement is not definite.

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Renato Renner May 02 2016 10:14 UTC

If I understand correctly, you are asking whether one should be worried if a theory leads to conclusions that are inconsistent, but which we cannot experimentally test directly. I think the answer is yes, for the same reason as I would for example be worried about a theory that tells me both “there

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Ioannis Kogias Apr 30 2016 19:08 UTC

Thanks a lot for the detailed explanation.
If I may call *A = (r = tail ==> w **?** ok)* a parameter that can take two values, then A is a free parameter of the theory and its value does not affect anything that is observable. Many theories may have such unobservable free parameters; e.g., cla

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Renato Renner Apr 30 2016 14:50 UTC

Excellent point. To start with your last question: Self-consistency of a theory T means that it does not make statements that contradict themselves. For example, in the Extended Wigner’s Friend gedankenexperiment described in the paper, it could happen that one may use a theory T in a certain way to

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Ioannis Kogias Apr 30 2016 02:17 UTC

Hi Renato,
it's great that you follow this site and reply to questions. Can i ask you the following, as it is very counter-intuitive to me and central to your paper: How is it possible to have two theories T1 and T2 that give exactly the same experimental predictions, but T1 is self-consistent whi

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Laura Mančinska Apr 29 2016 19:15 UTC

"... two parties, usually referred to as Alessandro and Bruno... "

Renato Renner Apr 29 2016 14:37 UTC

Exactly.

Frédéric Grosshans Apr 29 2016 10:49 UTC

Who ordered that ??

Cosmo Lupo Apr 28 2016 00:41 UTC

If I understand correctly, the result implies that quantum physics cannot consistently describe the macroscopic world, unless there are many of them.

Māris Ozols Apr 27 2016 22:31 UTC

For inspiration, [here][1] is the first editorial of a newly created open access linguistics journal called *[Glossa][2]*. This journal was established after the editorial board of another journal called *[Lingua][3]* resigned en masse after a disagreement with their owner Elsevier about the pricing

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Steve Flammia Apr 27 2016 08:13 UTC

I'm thrilled that John will finally publish his book.

Marco Piani Apr 26 2016 06:53 UTC

Scotland has a strong record of inspiring and inspired physicists ;-)

Māris Ozols Apr 25 2016 09:27 UTC

It is amazing that G. Nadurra has contributed to your research despite being just 16 years old!

Varun Narasimhachar Apr 15 2016 19:53 UTC

Interesting work... Could you please comment on possible connections of your work with those of Hayden and May (http://arxiv.org/abs/1210.0913) and of Portmann et al. (http://arxiv.org/abs/1512.02240)?

Stephen Jordan Apr 15 2016 15:02 UTC

This is a beautiful set of lecture notes.

Joe Fitzsimons Apr 05 2016 06:13 UTC

What I mean is that merely separating the process by which you choose each measurement setting and the entangling event does not actually close even this restricted version of the loophole. You need a further assumption that this choosing process produces a distribution of outcomes which are uncorre

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Marco Piani Apr 04 2016 14:45 UTC

No worries at all! I think I pressed the wrong button :-) And it is good to see that my answer was not totally off!

Bill Plick Apr 04 2016 11:48 UTC

Okay, I don't disagree. You seem to be implying that making this split is artificial? Why should this be the case for setting dependence (freedom of choice) but not for outcome dependence?

Robin Blume-Kohout Apr 03 2016 01:32 UTC

Oops! I see your answer now. Didn't mean to dupe it...

Steve Flammia Apr 01 2016 12:51 UTC

I put in a feature request for sorting comments by date.
https://github.com/scirate/scirate/issues/328