tag:blogger.com,1999:blog-22973357.post5855788592687571612..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Is there a smallest length?Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger65125tag:blogger.com,1999:blog-22973357.post-8549595253890444522018-04-07T17:58:55.884-04:002018-04-07T17:58:55.884-04:00Theoretically we can divide a number infinitely,li...Theoretically we can divide a number infinitely,like 1/2, 1/3, 1/4,1/5....thus infinitely. But practically it is impossible to divide matter infinitely. We have not yet discovered the smallest particle. Dividing matter means dividing it's mass. Mass is three dimensional. When we are sure that we have found the smallest particle we can take it as the basic unit of length. Measurement is forപി.കെ.രാമചന്ദ്രൻhttps://www.blogger.com/profile/12343085797019032020noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-34859394605117324342015-08-11T01:09:46.888-04:002015-08-11T01:09:46.888-04:00Hi tytung,
This recent post might answer your que...Hi tytung,<br /><br /><a href="http://backreaction.blogspot.com/2015/08/dear-dr-bee-why-do-some-people-assume.html" rel="nofollow">This recent post might answer your question</a>. Best,<br /><br />SabineSabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-90810607940245810592015-08-05T23:21:21.874-04:002015-08-05T23:21:21.874-04:00Regarding minimal length and length contraction, i...Regarding minimal length and length contraction, isn't it obvious that the value of Planck length is defined in a rest frame? - It is the minimum proper length that any observer can measure in his/her own rest frame.<br />Other frames may see that the minimum length is shortened, but that does not bring any physical implications of cause any problem.tytunghttps://www.blogger.com/profile/05777947785613061617noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-38847761172397776572014-09-22T11:42:33.797-04:002014-09-22T11:42:33.797-04:00Sabine:
I checked in Wikipedia, and the experime...Sabine: <br /><br />I checked in Wikipedia, and the experimental results you are talking about concern the speed of light dispersion. Nontrivial dispersion of "c" occurs only if you violate the local Lorentz symmetry.<br /><br />In Regge quantum gravity this does not happen, because the local Lorentz symmetry is preserved. Hence Regge QG is consistent with Lorentz symmetry and a A. Mikovichttps://www.blogger.com/profile/03175906801121515444noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31201046289085408432014-09-22T10:28:39.518-04:002014-09-22T10:28:39.518-04:00Sabine:
In the model I am talking about there is a...Sabine:<br />In the model I am talking about there is a local Lorentz invariance, which is not violated, i.e. the edge-lengths of a 4-simplex are invariant under the Lorentz transformations in that 4-simplex (recall that the spacetime metric is flat in each 4-symplex, but it is not a smooth function). What is violated are the smooth diffeomorphism transformations.<br /><br />Global Lorentz A. Mikovichttps://www.blogger.com/profile/03175906801121515444noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74756408002970366852014-09-21T17:13:38.395-04:002014-09-21T17:13:38.395-04:00I did a new theory idea on minimum distance that i...I did a new theory idea on minimum distance that included many of the ideas of posters here considered- in the form of a poems, with reversals of all the current issues of art and science funding and so on. It is on my blog and face book notes.L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-15181000271253766942014-09-20T13:37:01.146-04:002014-09-20T13:37:01.146-04:00Hush, I have enjoyed your Bob and Alice series of ...Hush, I have enjoyed your Bob and Alice series of post comments.<br /><br />In this general question of minimum distance, and of the distinction between things and notions. While drawing I said to my Artist roommate some decades back "It seems to me an artist tries to express things beginning with a minimum of lines to start with. " He said that was right. I was thinking where exactly L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78394726751487687742014-09-19T05:38:48.113-04:002014-09-19T05:38:48.113-04:00A. Mikovic:
Not correct. If you have any fixed ed...A. Mikovic:<br /><br />Not correct. If you have any fixed edge length it violates Lorentz-invariance and the constraints on this are much tighter, already well beyond the Planck scale. (Depends on the coupling in the effective limit.) Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42660697930996993312014-09-19T04:34:20.602-04:002014-09-19T04:34:20.602-04:00If one assumes that the spacetime is a PL manifold...If one assumes that the spacetime is a PL manifold corresponding to a triangulation, then the metric is determined by the edge lengths. If the space is a compact 3d manifold,<br />then there will be a minimal edge length L. If the number of the 4-simplices is large, then one can approximate the effective quantum dynamics by the effective action for the QFT with a momentum cutoff<br />hbar/L A. Mikovichttps://www.blogger.com/profile/03175906801121515444noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-462832784711171452014-09-18T20:53:09.131-04:002014-09-18T20:53:09.131-04:00DocG,
Ize roan speak English even as a minor poet ...DocG,<br />Ize roan speak English even as a minor poet we invent English.<br />You asked Sabine a damn good physics question (do we really want to know the answer? )<br />Thanks for the issue and inspiration. I made it the lead poem for my series in Facebook notes. SphereFarmer. I mean no disrespect. L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73610754103312639732014-09-18T18:04:58.647-04:002014-09-18T18:04:58.647-04:00Alice,
B.What if we wait?
A.Wait for what?
B.Wai...Alice,<br /><br />B.What if we wait?<br />A.Wait for what?<br /><br />B.Wait for the equation that finds<br />any prime.<br />A.What good will that do?<br /><br />B.That will give insight into the structure of numbers.<br /><br />A.This is a physics blog.<br />B.<br /><br />Q.Why didn't Bob answer Alice?<br />A.Bob decided to wait for insight into structure. Physical or not.<br /><br /><br />hushhttps://www.blogger.com/profile/16176588791118304829noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18184407682326760462014-09-18T17:48:07.414-04:002014-09-18T17:48:07.414-04:00I'll accept the simplest minimum length ... &...I'll accept the simplest minimum length ... "unable to resolve it beyond some limit "<br /><br />Here is my number <br />10^-18m<br />jalhttps://www.blogger.com/profile/16969819389823705458noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-34789632713426186642014-09-18T17:14:29.633-04:002014-09-18T17:14:29.633-04:00Mr. Otto.
Either you have some serious issues wit...Mr. Otto. <br />Either you have some serious issues with the English language or you are putting us on. I'm still waiting for Bee to respond to my question regarding Abramowicz's work.DocGhttps://www.blogger.com/profile/17359004200002936544noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-62833383757788251392014-09-18T15:17:24.199-04:002014-09-18T15:17:24.199-04:00If I ask - given the solar system, with the charac...If I ask - given the solar system, with the characteristic mass scale being that of the Sun or Jupiter, the characteristic length scale being that of a planetary orbit (a few A.U.), and Newton's constant - what is the characteristic time, based purely on dimensional analysis? <br /><br />The answer is, of course, that the characteristic times planetary orbital periods - i.e., of the order of Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-91314410180637808592014-09-17T17:14:03.201-04:002014-09-17T17:14:03.201-04:00DocG
I notice he has very recent papers on these i...DocG<br />I notice he has very recent papers on these issues. So why did you offer such a primitive paper? The symmetry looks like that preserved Lorentz as hyperbolic. The idea of rotating gyroscopes does not address deeper issues of chirality whenever that paper was offered.L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24450132023420730072014-09-17T16:47:22.168-04:002014-09-17T16:47:22.168-04:00DocG
I wonder what he would make of these ideas if...DocG<br />I wonder what he would make of these ideas if Abramowicz applied them to this interesting new observation?<br /><br />http://spacetelescope.org/news/heic1419/<br /><br />"Additionally, the results could affect theories of how such UCDs form. "This finding suggests that dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50307605869194237822014-09-17T13:41:57.845-04:002014-09-17T13:41:57.845-04:00Thanks Mr. Otto, but your response is extremely va...Thanks Mr. Otto, but your response is extremely vague and fanciful -- compared with the work of Abramowicz, which is very specific and solidly based on both observation and logic. It looks to me as though Abramowicz has achieved an important conceptual breakthrough -- comparable in some ways to that of Einstein in formulating GR. And I'm wondering why there appears to have been no followup toDocGhttps://www.blogger.com/profile/17359004200002936544noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67252182190884541622014-09-16T19:03:59.438-04:002014-09-16T19:03:59.438-04:00DocG
The universe itself as a physical totality c...DocG<br /> The universe itself as a physical totality can be so conceived.<br /> All things vibrate some day but bounded by what?<br /> Such an external principle may actually exist as a metaphysical mirror, say light speed negative and as with time reversed.<br />So, can we imagine exceeding cardinality and ordinality, complex spaces aside and zero to open ended arrow of time.<br />Even with L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84522208678872036642014-09-16T16:30:09.442-04:002014-09-16T16:30:09.442-04:00Has anyone ever considered that, as one approaches...Has anyone ever considered that, as one approaches the smallest length (presumably the Planck length), space might turn inside out? And that all those superparticles might be hiding in that inside out space?<br /><br />Marek Abramowicz's research on black holes suggests such a possibility. See for example his paper on the "Relativity of Inwards and Outwards"<br /><br /> http://DocGhttps://www.blogger.com/profile/17359004200002936544noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-11596277713537963642014-09-16T15:21:08.106-04:002014-09-16T15:21:08.106-04:00If phase space is "quantized" - as in ha...If phase space is "quantized" - as in has a minimum volume, where it doesn't make sense to talk of smaller volumes -- and one of spatial length, area or volume is also "quantized", then so must momentum, and vice versa? Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-54050251039869730222014-09-16T06:39:18.801-04:002014-09-16T06:39:18.801-04:00Thanks for the reply Bee. Your interpretation is t...Thanks for the reply Bee. Your interpretation is the one I can understand :)<br /><br />Cheers,<br />NirmalyaNirmalyahttps://www.blogger.com/profile/00482736027241310182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28374036535824330782014-09-16T04:50:58.082-04:002014-09-16T04:50:58.082-04:00Nirmalya:
Well, if you want a modification for a ...Nirmalya:<br /><br />Well, if you want a modification for a free particle then gravity is weak (for all particles we know), so (global) Lorentz-invariance is what you expect when you change coordinate frames. Now why you would expect there to be any effect for that particle if gravity is weak is a different question and I'm the wrong person to ask. The argument that I normally get to hear is Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-16049308907518082532014-09-15T17:11:34.211-04:002014-09-15T17:11:34.211-04:00Andrii,
One bit is not enough to clarify things as...Andrii,<br />One bit is not enough to clarify things as it can be fuzzy in between or 1 or 0 to show there must be a minimum length or duration as these can represent a line or point in the context of a more general space. As we can add more groups of bits, this paradox still remains for each unitary bit.L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21206734428296703112014-09-15T16:50:17.010-04:002014-09-15T16:50:17.010-04:00Kneemo, between the holophrasic and the staccato (...Kneemo, between the holophrasic and the staccato (old linguistic terms) or the holographic and fractal emergent views, quasi-contiguity both incorporating these symmetry concepts or not - your great question occurred to me too. Minimum distance grounded when the Planck context is higher volume.L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-56885357411278774792014-09-15T15:57:57.256-04:002014-09-15T15:57:57.256-04:00Hi Bee
There's one more thing that confuses m...Hi Bee<br /><br />There's one more thing that confuses me - when one speaks of the possible tension between an invariant minimal length and Lorentz transformations, is one speaking in the context of a. flat space field theory? That would seem odd, because we've chosen to neglect gravity there in the first place. If gravity became important global Lorentz symmetry would be lost anyway. or Nirmalyahttps://www.blogger.com/profile/00482736027241310182noreply@blogger.com