tag:blogger.com,1999:blog-22973357.post5111804177290470081..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Information transfer without energy exchangeSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger41125tag:blogger.com,1999:blog-22973357.post-74272344680365933292015-05-21T01:14:42.072-04:002015-05-21T01:14:42.072-04:00Achim, the interpretative claim in Hotta's pap...Achim, the interpretative claim in Hotta's paper is more or less equivalent to yours and it is equally incorrect, too.<br /><br />The particular mistakes in your paper are all the sentences that visibly don't follow from the surrounding technical material.<br /><br />From a term's scaling like O(lambda_A*lambda_B), it doesn't follow that no quanta are being exchanged, as you claimLuboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-33365362223779813272015-05-19T11:21:32.814-04:002015-05-19T11:21:32.814-04:00Another comment from Achim
Lubos, regarding your ...Another comment from Achim<br /><br /><i>Lubos, regarding your intuition, notice that it is also possible to send energy from Alice to Bob without the energy actually traveling between Alice and Bob. It is called quantum energy teleportation:<br /><br />http://arxiv.org/abs/1101.3954</i>Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-17018690947817376562015-05-19T10:49:47.156-04:002015-05-19T10:49:47.156-04:00ppnl,
Sorry, I thought you had meant information ...ppnl,<br /><br />Sorry, I thought you had meant information transfer from the sender. In the case you think about, I don't see how this can work without energy transmission. Think of a double-slit where you either block or unblock the second slit, thereby changing the interference pattern on some location on the screen. The reason you get this change is that you are blocking out part of the Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75520033588211560032015-05-19T10:45:14.828-04:002015-05-19T10:45:14.828-04:00Another comment from Achim:
Lubos,
Please read ...Another comment from Achim:<br /><br /><i>Lubos, <br /><br />Please read the paper and then let us know in which step you believe we went wrong. </i>Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75391036216096301762015-05-18T22:31:36.898-04:002015-05-18T22:31:36.898-04:00In absence of relationship a binary bit has no sig...In absence of relationship a binary bit has no significance. Only as a part of a larger, meta-level framework does it have any real magnitude. As with energy, information in measured in a change of state.<br />For example, Bob is in a dark room with a light proof window that can be opened to view some pleasant terrestrial vista. Alice calls Bob on a cell phone and says, “Open your window.” Bob Don Fosterhttps://www.blogger.com/profile/04814669413022486958noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-83851529065359505112015-05-18T12:33:01.356-04:002015-05-18T12:33:01.356-04:00The transport of information is in no way a "...The transport of information is in no way a "calculation" operation because there is no processing of information. Only the write operation to the destination should be considered a computing operation requiring 1) information storage 2) modification of the stored information. Reading is only a epistemological need to be able to claim that a storage of information does really exist.<br Nicolas Pouparthttps://www.blogger.com/profile/17722878242014554884noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50057467002730819602015-05-18T01:33:12.683-04:002015-05-18T01:33:12.683-04:00Achim, the massless propagator is constant in the ...Achim, the massless propagator is constant in the time-like region in 1+1 dimensions but aside from simplicity and integrability, it changes nothing about the general ways how energy and information propagate. Only the quantitative profiles are different than in other dimensions.<br /><br />To send information, one still has to perturb the field at the initial place in a time-dependent way, and Luboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-17661624845050890802015-05-18T01:00:39.675-04:002015-05-18T01:00:39.675-04:00Another comment on behalf of Achim
"In reply...Another comment on behalf of Achim<br /><br /><i>"In reply to Lubos' comments: <br /><br />Lubos, have a look at the paper. You'll find that we explain that in most dimensions information and energy transport cannot be cleanly separated because energy leaks into the lightcone. And that is why we explain at great length that in 1+1 dimensions one can cleanly separate info and energy Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-349319384949857912015-05-17T13:22:34.384-04:002015-05-17T13:22:34.384-04:00@Andrew Thomas - in the base paper, they do not sa...@Andrew Thomas - in the base paper, they do not say that, they have much more complicated systems. Of course I know I may be completely wrong. <br /><br />But for simple case, consider this: Casimir like settings - two plates, and standing vacuum waves between them. In classical setting You have to propel this system by transferring energy in order to have standing waves running. But in quantum Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68090937852363664972015-05-17T12:52:16.979-04:002015-05-17T12:52:16.979-04:00@Libos, @Thomas - they agreed on protocol. So it i...@Libos, @Thomas - they agreed on protocol. So it is true, that not all information is sent without energy. But as they have protocol based on local observation, and local time measuring - <b> some information</b> may be sent without energy. <br /><br />But this is not the aim of the article we disputing about - it was just loose co-comment to Your comment. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75547604956748072892015-05-17T05:24:07.841-04:002015-05-17T05:24:07.841-04:00fiksacie, so if Alice and Bob get together and exc...fiksacie, so if Alice and Bob get together and exchange information then that means that Alice and Bob can communicate without sending information. Hmm, I think I see a flaw in your reasoning.<br /><br />Back to the paper. Information always refers to some aspect of the physical world, be it a bit in a computer or a quantum state vector. It is meaningless to talk of information with no physical Andrew Thomashttps://www.blogger.com/profile/11075608749064975687noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5830093083908967172015-05-17T03:41:16.208-04:002015-05-17T03:41:16.208-04:00Dear fiksacie, for A and B to agree about the conv...Dear fiksacie, for A and B to agree about the conventions, codes, and protocols, they need to send even more information - and more energy - than without it. So whatever you write, when interpreted rationally, only *strengthens* my self-evidently correct point that one can't send information without sending energy.Luboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-19173505649314448652015-05-17T03:39:07.847-04:002015-05-17T03:39:07.847-04:00Sabine, I haven't seen any evidence that the p...Sabine, I haven't seen any evidence that the propagation of information may be decoupled from the propagation of energy.<br /><br />In odd spacetime dimensions, the propagator is nonzero in the timelike interior of the light cone which means that both information *and* energy created at the source are initially moving slower than light. <br /><br />It makes no sense to say that this Luboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9437148239888221082015-05-16T14:25:32.526-04:002015-05-16T14:25:32.526-04:00@Lubos "But if one knows what the digit is, n...@Lubos "But if one knows what the digit is, namely that it's "0", then the amount of information that is sent is zero. Information is only being sent if one doesn't know in advance what he will receive. " - no, because You do not set enough context in the protocol. For send some portion of information, You need some kind of code, protocol etc. The simplest protocol is Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80267391514537839182015-05-16T14:18:33.661-04:002015-05-16T14:18:33.661-04:00Dear Bee, let me expand my comment. In undergradu...Dear Bee, let me expand my comment. In undergraduate physics we learn the following for wave velocity, group velocity and the speed of light for electromagnetic radiation.<br /><br />V_wave * V_group = c * c<br /><br />We are then assured that V_group, the speed at which energy propagates, is always less than c; and since information transfer requires energy, no information transfer can happen Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-87069526061214509482015-05-16T11:51:16.351-04:002015-05-16T11:51:16.351-04:00Bee,
"Yes, good point. You can of course sen...Bee,<br /><br />"Yes, good point. You can of course send information without it being accompanied by energy, and you don't even need quantum mechanics for this. We can just agree that if you don't show up by 8pm, we will meet later at the movies, so then your non-appearance has sent me information without any energy. But we previously had to agree on some code for this. The quantum ppnlhttps://www.blogger.com/profile/01720719028496317693noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-77240615241611981072015-05-16T08:09:58.752-04:002015-05-16T08:09:58.752-04:00Lubos,
You're right, but that isn't what ...Lubos,<br /><br />You're right, but that isn't what they're saying in the paper. There is a (local) exchange of energy between the field and the detector (explicitly present in the Hamiltonian) and there is also a propagation of energy in the field, it's just that the energy doesn't entirely propagate together with the information. It's a massless field, the energy ('Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21274994548413536622015-05-16T08:00:27.405-04:002015-05-16T08:00:27.405-04:00Concerning Dr Kempf's reply to my objections. ...Concerning Dr Kempf's reply to my objections. Well, it does look like - as someone has pointed out - that he suggests that if sending "0" means to do nothing, then one may send "0" without any expenditure of energy.<br /><br />But if one knows what the digit is, namely that it's "0", then the amount of information that is sent is zero. Information is only Luboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18032923311727058712015-05-16T01:59:49.343-04:002015-05-16T01:59:49.343-04:00Arun: The points are timelike separated, not space...Arun: The points are timelike separated, not spacelike separated. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-82609313503942996302015-05-15T08:42:37.824-04:002015-05-15T08:42:37.824-04:00If we can send information without energy, what pr...If we can send information without energy, what prevents this information exchange from propagating faster than the speed of light? Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26970167451914129552015-05-15T08:39:48.940-04:002015-05-15T08:39:48.940-04:00Thanks, AchimThanks, AchimAndrew Thomashttps://www.blogger.com/profile/11075608749064975687noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-86348665733551798252015-05-15T07:15:15.961-04:002015-05-15T07:15:15.961-04:00To clear things a little. I do not understand the ...To clear things a little. I do not understand the whole theory beside it, but is seems to me they state that:<br /><br />0. _massless_ field is used. For 3+1D Minkowski space it has correlation only on null lightcone. 2n +1D Minkowski spacetime is different.<br />1. information is transfered within lightcone ( null or timelike separation) in 2n +1D dimension<br />2. the same effect is possible inAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72194974018230052942015-05-15T02:02:21.482-04:002015-05-15T02:02:21.482-04:00Hi All,
I'm posting a comment on behalf of Ac...Hi All,<br /><br />I'm posting a comment on behalf of Achim Kempf, on of the paper's authors<br /><br /><i>"Great to see all this interest!<br /><br />Lubos wrote: "Those authors do (incorrectly) claim that the sender doesn't spend energy, it's really their main point."<br /><br />Actually, we don't claim any such thing. Of course both Alice and Bob invest Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-60434613996070254982015-05-14T20:23:39.555-04:002015-05-14T20:23:39.555-04:00energy doesn't travel with information? that d...energy doesn't travel with information? that doesn't make any sense. information travels via energy. it's called modulation. you vary some aspect of the carrier energy (amplitude, frequency, phase) to encode the information.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-7090901880641406202015-05-14T12:44:16.112-04:002015-05-14T12:44:16.112-04:00Sabine, I am afraid that you're confused. In a...Sabine, I am afraid that you're confused. In all - curved, n-dimensional - spacetimes, the equal-time commutators are still as simple as the usual ones. The field only has a nonzero commutator with its time (coordinate perpendicular to the slice) derivative and the commutator is the delta-function times the obvious thing dictated by the local Lorentz symmetry.<br /><br />Equal time Luboš Motlhttps://www.blogger.com/profile/17487263983247488359noreply@blogger.com