tag:blogger.com,1999:blog-22973357.post8952150869134959798..comments2018-11-18T15:47:03.795-05:00Comments on Backreaction: Which problems make good research problems?Sabine Hossenfelderhttps://plus.google.com/111136225362929878171noreply@blogger.comBlogger33125tag:blogger.com,1999:blog-22973357.post-43554088105419709862018-03-29T04:33:24.287-04:002018-03-29T04:33:24.287-04:00Unknown
I am not a proponent of "hidden vari...Unknown<br /><br />I am not a proponent of "hidden variables". To me, QM is a complete, efficient and tested theory about "what we can say about nature".<br /><br />QM is an extension of classical physics taking into account physical objects AND the observer. All we can do is to compute probabilities.<br /><br />To me, there is no such thing as a “measurement problem”, the C. M.https://www.blogger.com/profile/11833932638167107741noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28646838145516814032018-03-28T20:04:29.682-04:002018-03-28T20:04:29.682-04:00C.M.
You seem to be falling victim to a hidden va...C.M.<br /><br />You seem to be falling victim to a hidden variables theory when you say "'Superposition' is on the observer’s side."<br />Superposition is physical, and not a statement about the observer's knowledge. There is no true underlying state, latent and waiting to be measured. If you want confirmation of this, check out the Bell Inequalities.<br /><br />Unless I'Unknownhttps://www.blogger.com/profile/00690730031820277093noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1268165647381732572018-02-21T17:26:52.824-05:002018-02-21T17:26:52.824-05:00andrew - such a theory would be a massive breakthr...andrew - such a theory would be a massive breakthrough, and it would be followed by normal science at a higher level, because you could predict the next decimal place of the SM constants, and then test it. Mitchellhttps://www.blogger.com/profile/10768655514143252049noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18728791606289144322018-02-19T14:59:29.914-05:002018-02-19T14:59:29.914-05:00One interesting class of problems that doesn't...One interesting class of problems that doesn't seem to fit neatly into this schema are "why" problems which I also sometimes call in the area of fundamental physics "within the Standard Model" problems.<br /><br />Imagine (possibly contra-factually) that the Standard Model is all that there is to non-gravitational physics and that we measure all of the constants in the andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-54401560483287062632018-02-10T09:34:33.624-05:002018-02-10T09:34:33.624-05:00Schrodinger's cat and quantum entanglement are...Schrodinger's cat and quantum entanglement are effects arising from the absence of a third reference frame/observer.It is the third observer who defines what is a 0 or 1 state. Stuart https://www.blogger.com/profile/12767480095489975264noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-77132581228271009212018-02-10T05:06:23.446-05:002018-02-10T05:06:23.446-05:00ppnl,
Concerning the "Schrödinger cat":...ppnl,<br /><br />Concerning the "Schrödinger cat": For me, the quantum measurement is an update of the observer's knowledge. The observer’s knowledge about the cat is in a superposition until she/he makes a measurement. “Superposition” is on the observer’s side. It’s not a physical thing. <br />And yes, in quantum mechanics there is a fundamental randomness which forces you to use C. M.https://www.blogger.com/profile/11833932638167107741noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2395601721773326262018-02-10T05:05:05.047-05:002018-02-10T05:05:05.047-05:00ppnl,
Concerning the "Schrödinger cat":...ppnl,<br /><br />Concerning the "Schrödinger cat": <br />For me, the quantum measurement is an update of the observer's knowledge. The observer’s knowledge about the cat is in a superposition until she/he makes a measurement. “Superposition” is on the observer’s side. It’s not a physical thing.<br />And yes, in quantum mechanics there is a fundamental randomness which forces you to C. M.https://www.blogger.com/profile/11833932638167107741noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-19320811429065556662018-02-09T15:02:32.577-05:002018-02-09T15:02:32.577-05:00C.M.,
The problem is that in QM it was unclear ex...C.M.,<br /><br />The problem is that in QM it was unclear exactly what a measurment is. For example Schrödinger's cat is presumed to be in a combination of alive/dead state until it is measured. But the cat can clearly see if the poison vial broke. Why isn't that a measurment? It wouldn't make any difference in classical physics but in quantum physics it becomes very important.<br /><ppnlhttps://www.blogger.com/profile/01720719028496317693noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27951458986375648872018-02-09T08:11:35.512-05:002018-02-09T08:11:35.512-05:00Convince yourself that the mini-problem shown in t...<i>Convince yourself that the mini-problem shown in the top image is mathematically ill-posed unless you appeal to Occam’s razor.</i><br /><br />The problem is ill posed because there are an infinite number of functions that can generate any finite sequence of numbers. The "real" solution depends on the implicit conditions that the writer of the puzzle added, i.e., it must be solvable Rob van Son (Not a physicist, just an amateur)https://www.blogger.com/profile/12611755507524401026noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74695322343460273652018-02-09T05:11:53.725-05:002018-02-09T05:11:53.725-05:00Hello,
"measurement problem in quantum mecha...<br />Hello,<br /><br />"measurement problem in quantum mechanics" ??<br /><br />I never understood the "measurement problem" in quantum mechanics. I do not see any "problem" but just a "measurement". <br /><br />I always understood quantum states as information about physical objects and not as physical objects themselves. Just like a Gaussian distributionC. M.https://www.blogger.com/profile/11833932638167107741noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-60087244622497753082018-02-09T04:12:05.391-05:002018-02-09T04:12:05.391-05:00Thanks for the awesome reference list and cool cla...Thanks for the awesome reference list and cool classification! <br />Personally I'd assign more meaning to DM and DE, but such subtleties will hopefully be easy to assess in a few years. <br />I can't help saying that I'm very glad whenever people speak about QFT expansion issues. No need for me to expand about how real, tough and long-standing problems are customarily dismissed as Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80646667626947938022018-02-08T17:00:11.519-05:002018-02-08T17:00:11.519-05:00Bee,
I know he comes up often in discussions of s...Bee,<br /><br />I know he comes up often in discussions of scientific methodology and the like, but Kuhn's theory really doesn't seem to hold up at the end of the day. And not for any reasons concerning misplaced relativism or social constructivism (though I do, as would most other scientists, disagree with either of those ideas of what science "is" as being remotely true).<br /petehttps://www.blogger.com/profile/12969621709127674152noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80058627920639396082018-02-08T15:22:12.444-05:002018-02-08T15:22:12.444-05:00I think that you are missing out on a whole catego...<br /> I think that you are missing out on a whole category of problems - 'unknown problems'. <br /><br />In today's world, it's likely Einstein would never get published and Newton would be only selling horoscopes. These people looked at what was going on in the world around them and struck out in directions that were essentially orthogonal to current thought, paying little heed Tom Andersenhttps://www.blogger.com/profile/17562906116020498110noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-23541132348535498042018-02-08T13:00:35.825-05:002018-02-08T13:00:35.825-05:00Homework assignment: Convince yourself that the mi...<i>Homework assignment: Convince yourself that the mini-problem ("What number fits into the last triangle?") shown in the top image is mathematically ill-posed unless you appeal to Occam’s razor.</i><br /><br />I took a crack at the so-called mini-problem and found that numbers such as 5, .5, <i>e</i>, as well as many more, fit out-of-the-box. I tried fitting additional numbers, by Pablo Pihttps://www.blogger.com/profile/06729509180637606783noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27124739453321870762018-02-08T12:47:40.875-05:002018-02-08T12:47:40.875-05:00Sabine,
No, decoherence does not explain how one...Sabine, <br /><br />No, decoherence does not explain how one possibility is selected. But I doubt anything can. It is not a deterministic process so there cannot be a causal explanation. It isn't even clear what would count as an explanation.<br /><br />But what decoherence does is tell us exactly what a measurement is. A measurment is nothing more than an interaction that causes decoherence.ppnlhttps://www.blogger.com/profile/01720719028496317693noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75207927424730323192018-02-08T11:54:35.603-05:002018-02-08T11:54:35.603-05:00Amos,
Yes, even Occam's razor allows various ...Amos,<br /><br />Yes, even Occam's razor allows various "equally good" explanations.<br /><br />I use the term "foundations of physics" to mean "the fields concerned with what is presently most fundamental," meaning (parts of) cosmology, particle physics, quantum foundations, and quantum gravity. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8624815520104963572018-02-08T11:08:55.122-05:002018-02-08T11:08:55.122-05:00Convince yourself that the mini-problem shown in t...<i>Convince yourself that the mini-problem shown in the top image is mathematically ill-posed unless you appeal to Occam’s razor.</i><br /><br />Yes, and even with Occam’s razor it may be ambiguous. Labeling the triangle vertices a,b,c counter-clockwise from top, one person might notice that the central number is always ab-c, but another person might notice that the central number is always (Amoshttps://www.blogger.com/profile/00595591283398023248noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40551792013771897842018-02-08T10:39:05.519-05:002018-02-08T10:39:05.519-05:00Re Michael Sarnowski and Bee: Baryogenesis, Tully...Re Michael Sarnowski and Bee: Baryogenesis, Tully-Fisher, QM versus GR have no "acceptable" observations remaining by kind. Physics' log-log plots never terminate, demanding "bigger." Minimum $1.4 billion <a href="http://www.dunescience.org/neutrino-detectors/" rel="nofollow">DUNE</a> dark matter detector is 68,000 tons of liquid argon 4850 feet underground.<br /><br />Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-43570786594942347192018-02-08T09:43:24.305-05:002018-02-08T09:43:24.305-05:00A good read; and I agree.
I've followed a dif...A good read; and I agree. <br />I've followed a different road - fractals - to the cosmology and quantum problems; actually it was the other way around, I found these problems and solutions in the fractal and got to know cosmology and quantum from them. I think the fractal attractor is being ignored, but it has been fun for me. <br />BBlair Macdonaldhttps://www.blogger.com/profile/05795107163513936768noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27386191828180057752018-02-08T03:09:31.179-05:002018-02-08T03:09:31.179-05:00Michael,
This option is not available for the fou...Michael,<br /><br />This option is not available for the foundations of physics. Experiments are too costly. You can't do them all - some selection has to be made. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-30935509594845108602018-02-08T03:03:32.184-05:002018-02-08T03:03:32.184-05:00My dad always said, ask the material the question....My dad always said, ask the material the question. I think what he understood is that the research to figure out which is the best way to test, wastes a lot more energy than just testing everything. Like always. This rule is right 80-90 percent of the time.Michael John Sarnowskihttps://www.blogger.com/profile/00528454593064091302noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32249934684588582012018-02-08T02:01:38.888-05:002018-02-08T02:01:38.888-05:00Jeff,
It's not an advertisement. I placed it ...Jeff,<br /><br />It's not an advertisement. I placed it there. I understand what the comments refer to. Please also see the PS to my blogpost for context.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72547779765830299112018-02-08T01:36:17.041-05:002018-02-08T01:36:17.041-05:00Bee, I'm curious. Did you understand the comme...Bee, I'm curious. Did you understand the comments that start "Re: the problem ..." and "the next number in the series..."? Those comments are there because your blog is showing a block at upper right that I think is advertising but your readers (including me, initially) thought was a problem posed by you. Are they confused or am I?Jeffhttps://www.blogger.com/profile/06140726210295297492noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31408958492424216752018-02-08T00:44:31.354-05:002018-02-08T00:44:31.354-05:00Stephen,
It's a finetuning problem, and hence...Stephen,<br /><br />It's a finetuning problem, and hence it's not a well-defined problem unless you have a probability distribution for the parameter to show that the measured value is unlikely.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31379378731807044572018-02-08T00:43:10.228-05:002018-02-08T00:43:10.228-05:00ppnl,
Decoherence doesn't solve the measureme...ppnl,<br /><br />Decoherence doesn't solve the measurement problem, it merely explains why pure states decohere to mixed states. It does not explain the update to an eigenstate upon measurement. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.com