tag:blogger.com,1999:blog-22973357.post4081926860208158427..comments2019-09-22T19:01:08.396-04:00Comments on Sabine Hossenfelder: Backreaction: Good Problems in the Foundations of PhysicsSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger126125tag:blogger.com,1999:blog-22973357.post-67179872559327848872019-06-06T13:28:10.505-04:002019-06-06T13:28:10.505-04:00rturpin,
The Born rule is indeed an extra rule th...rturpin,<br /><br />The Born rule is indeed an extra rule that breaks the unitarity of the Schrodinger equation and introduces a classical macroscopic observer into the mix. Figuring out how the classical observer and the Born rule emerge as the quantum systems scale up and become open has been an open problem for almost a century. Current best guesses are related to Zurek's einselection, Sergeihttps://www.blogger.com/profile/15415152744605672336noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-12846108571006406312019-06-06T11:38:09.264-04:002019-06-06T11:38:09.264-04:00Would I be amiss in viewing the ad hoc and not ent...Would I be amiss in viewing the ad hoc and not entirely rigorous nature of the Born rule as what covers over the inconsistency of the measurement problem? In both classical mechanics and GR, you can make all sorts of gizmos that act as observers, which follow only the physics the theory. With QM, we pull the Born rule out of our sleeves at the end. That seems wrong. Not in the sense of the "rturpinhttps://www.blogger.com/profile/14474176390371518034noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36608208666915475532019-02-10T10:09:27.962-05:002019-02-10T10:09:27.962-05:00Sabine, I should think the zero point energy (vacu...Sabine, I should think the zero point energy (vacuum energy, cosmological constant) problem is worth investigation. Experiments can be done with it (Casimir effect, Lamb-Retherford), and the measured value and theoretical value are wildly different. Perhaps other experiments can be devised to just mess with it, and see if it varies under different conditions.<br /><br />Perhaps theory can be Dr. A.M. Castaldohttps://www.blogger.com/profile/17988116835722393503noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-34719773253511202792019-02-01T11:48:21.816-05:002019-02-01T11:48:21.816-05:00Neo,
It's not a promising research topic for ...Neo,<br /><br />It's not a promising research topic for the reasons I laid out in my blogpost.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28528169145301298312019-02-01T10:49:40.819-05:002019-02-01T10:49:40.819-05:00Bee,
isn't that a good question? what determi...Bee,<br /><br />isn't that a good question? what determines the yukawa couplings of elementary fermion particles? neohttps://www.blogger.com/profile/16769182614452171312noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-46521863449342923952019-02-01T02:49:27.849-05:002019-02-01T02:49:27.849-05:00Neo,
Yes, that's the same problem.Neo,<br /><br />Yes, that's the same problem. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9905230463839890882019-01-31T23:00:39.365-05:002019-01-31T23:00:39.365-05:00"Particle Masses
It would be nice to have a w..."Particle Masses<br />It would be nice to have a way to derive the masses of the particles in the standard model from a theory with fewer parameters, but there is nothing wrong with these masses just being what they are. Thus, not a good problem."<br /><br />isn't this explained in terms of the yukawa couplings of fermions with the higgs field?<br /><br />but then that leads to the neohttps://www.blogger.com/profile/16769182614452171312noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-55037359012978669452019-01-31T15:05:17.203-05:002019-01-31T15:05:17.203-05:00Dear Sabine,
OMG! You included "The Measurem...Dear Sabine,<br /><br />OMG! You included "The Measurement Problem" too?!!<br /><br />Thanks for including that one too, hummmmm ... ? <br /><br />...<br /><br />OK. <br /><br />Best regards, and sincerely,<br /><br />--Ajit<br />Ajit R. Jadhavhttps://www.blogger.com/profile/02194541129055576042noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-70985051605963529272019-01-19T08:35:11.143-05:002019-01-19T08:35:11.143-05:00"You have a wavefunction that contains infini..."You have a wavefunction that contains infinitely many universes. How many of those are contained in your "physicist"? How do you decide?"<br /><br />As a partial answer to Sabine's question: it may or may not be possible depending on the wavefunction. In the idealized setting described in my previous comment (a physicist performing n consecutive measurement) Sabine will Pascalhttps://www.blogger.com/profile/14201150679841329835noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-13001465759284240232019-01-19T02:39:52.997-05:002019-01-19T02:39:52.997-05:00I think that there is a misleading concerning with...I think that there is a misleading concerning with energy and mass. Signals at speed c changing gravitational field can be modelled as mass distribution change when emitted or absorbed - they have no mass or gravitational INTERaction meanings "at flight".<br /><br />My understaning of equivalencies:<br />- slow energy ~ mass ~ gravity ~ time<br />- energy at speed c ~ volume - Eusahttps://www.blogger.com/profile/14114706429392111062noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-4136770076660871542019-01-19T01:29:19.137-05:002019-01-19T01:29:19.137-05:00Hi Sabine,
I hope I was being clear. In your vide...Hi Sabine,<br /><br />I hope I was being clear. In your video describing MOND, you described rock solid galactic rotation. I hope that makes my position transparent without contradicting established facts.<br /><br />regards <br />Marco ParigiMarco Parigihttps://www.blogger.com/profile/00702055111711651319noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31539321903440197462019-01-19T00:14:14.056-05:002019-01-19T00:14:14.056-05:00Eusa,
Because the parameter in question is not a ...Eusa,<br /><br />Because the parameter in question is not a mass. It's parameterized as a fluid which has the properties of matter. We do not know if it is made of particles which have a mass. Indeed the word "dark mass" would be much more misleading. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21725940610520663262019-01-18T21:17:19.513-05:002019-01-18T21:17:19.513-05:00Hi Sabine,
At the risk of failing comment moderat...Hi Sabine,<br /><br />At the risk of failing comment moderation, a couple of people have repeated the phrase <i>observed/inferred CDM </i>.<br /><br /><br />Now for those of you that have seen Sabine's video, the amount of Dark Matter that is <i> "observed/inferred"</i> in Galaxies at least, is the amount of mass required in an assumed Halo that balances Einstein's (and Newton&#Marco Parigihttps://www.blogger.com/profile/00702055111711651319noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-63759708942212776742019-01-18T16:57:39.408-05:002019-01-18T16:57:39.408-05:00@Sabine: Here is a fun idea. What is the *actual* ...@Sabine: Here is a fun idea. What is the *actual* distribution of dimensionless numbers in the existing physics that we know works? I imagine we can generate all kinds of dimensionless ratios so we at least have a testable sample. <br /><br />We could find at least the median, and see how close it is to 1.0.<br /><br />We could also test the mode (maybe half-sample mode, another robust statistic)Dr. A.M. Castaldohttps://www.blogger.com/profile/17988116835722393503noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78092874781466660482019-01-18T14:08:53.966-05:002019-01-18T14:08:53.966-05:00I wonder why we call extra gravity and mass as &qu...I wonder why we call extra gravity and mass as "dark matter". Being scientific why not calling it "dark mass" as a parameter of theory?<br /><br />Word "matter" means prejudice and affects bias in research.Eusahttps://www.blogger.com/profile/14114706429392111062noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36514717470519473892019-01-18T09:52:23.606-05:002019-01-18T09:52:23.606-05:00"The “problem” with the MACHOs observed so fa...<i>"The “problem” with the MACHOs observed so far is that they can comprise, at most, a small fraction of the observed/inferred CDM within the smallish part of the MW that has been probed by this technique so far."</i><br /><br />In general, this is true. I'm even co-author on a<a href="http://www.astro.multivax.de:8000/helbig/research/publications/info/microlensing_qsos.html" rel=Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79607193156733087632019-01-18T07:07:04.051-05:002019-01-18T07:07:04.051-05:00"You have a wavefunction that contains infini..."You have a wavefunction that contains infinitely many universes. How many of those are contained in your "physicist"? How do you decide?"<br /><br />Infinitely many, but for all practical purposes just one.<br /><br />Sorry, I fail to see why this is not obvious. Perhaps I am only thinking superficially about the matter.<br /><br />Two quantum states of a macroscopic object (Ripihttps://www.blogger.com/profile/09419424448726883928noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27583743680145531482019-01-18T03:43:58.882-05:002019-01-18T03:43:58.882-05:00Sabine, I think you're asking how to chop up t...Sabine, I think you're asking how to chop up the universal wavefunction in a bunch of separate universes. That is a valid question which can hopefully be addressed by decoherence and / or MWI theorists. I don't know how much has been done already, and to what extent this is still work in progress. You'd have to ask the experts for that. <br /><br />Nonetheless, I maintain that the Pascalhttps://www.blogger.com/profile/14201150679841329835noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-22581206731763891952019-01-17T23:29:57.164-05:002019-01-17T23:29:57.164-05:00Pascal,
I think we are talking past each other. C...Pascal,<br /><br />I think we are talking past each other. Calling an "observer" a "physicist" doesn't answer my question. You have a wavefunction that contains infinitely many universes. How many of those are contained in your "physicist"? How do you decide?Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2718586485166895042019-01-17T21:09:03.361-05:002019-01-17T21:09:03.361-05:00JeanTate said :
Marco Parigi,
Sabine may not ap...JeanTate said : <br /><br /><i>Marco Parigi,<br /><br />Sabine may not approve this nitpick comment, but here goes anyway.</i><br /><br />Sabine does not have a problem with you (or me for that matter) but what I am saying about the falsification status of Dark Matter.<br /><br />Yes, I do realise that MACHOs cover a lot of different possibilities including real observable matter, and presumably Marco Parigihttps://www.blogger.com/profile/00702055111711651319noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40619849630905853022019-01-17T11:57:37.098-05:002019-01-17T11:57:37.098-05:00Sabine: you can think of a physicist that performs...Sabine: you can think of a physicist that performs the same experiment repeatedly, with say two possible results each time (say "spin up" or "spin down" or whatever it is that the experimenters measure).<br />Then you can look at the sequence of past results obtained by the experimenter.<br />Note that this is a well defined sequence of 0's and 1's (but as I pointed Pascalhttps://www.blogger.com/profile/14201150679841329835noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-17174710593331313862019-01-17T11:36:55.016-05:002019-01-17T11:36:55.016-05:00Pascal, Who or what is an "observer" so ...Pascal, Who or what is an "observer" so that you can speak of their probability? Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-59355821965858881272019-01-17T11:33:33.299-05:002019-01-17T11:33:33.299-05:00"The problem with many worlds is to figure ou..."The problem with many worlds is to figure out the probabilities of whom or what it is that you are even calculating."<br /><br />It seems to me that there is a clear frequentist interpretation of probabilitites if you look at the *past* results of measurements performed by an observer.<br />If you look at future results, the situation is different because the results<br />are not Pascalhttps://www.blogger.com/profile/14201150679841329835noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-83220796493277113132019-01-17T11:26:22.634-05:002019-01-17T11:26:22.634-05:00Thanks again. I accept that everybody will have it...Thanks again. I accept that everybody will have it's own interpretation of what the theory means. I accept that you see problems of interpretation that I don't, probably because you have thought and studied more about these issues than I have, but shouldn't we all at least agree on a common set of postulates?Ripihttps://www.blogger.com/profile/09419424448726883928noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-44235305427780119942019-01-17T10:27:48.547-05:002019-01-17T10:27:48.547-05:00Ripi,
I may have expressed this unclearly. The pr...Ripi,<br /><br />I may have expressed this unclearly. The probabilities that you calculate using the standard procedure are the same, of course, but that's "shut-up and calculate". The problem with many worlds is to figure out the probabilities of whom or what it is that you are even calculating.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.com