tag:blogger.com,1999:blog-8666091.post6175893445664723756..comments2021-04-08T20:46:06.023+02:00Comments on The Reference Frame: Confusions about the relationships of special relativity and general relativityLuboš Motlhttp://www.blogger.com/profile/17487263983247488359noreply@blogger.comBlogger28125tag:blogger.com,1999:blog-8666091.post-60660538533726750102015-03-03T08:50:48.921+01:002015-03-03T08:50:48.921+01:00A simple analysis of "Motion", using not...A simple analysis of "Motion", using nothing but your mind, eventually leads you to independently discovering Special Relativity, along with independently deriving all of the SR equations. No previous education in physics is required to accomplish this. Then, everyone ignores your achievement. Go figure ???<br /><br />http://goo.gl/fz4R0IK Sean Proudlernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-30284591830049027842014-06-29T23:59:09.003+02:002014-06-29T23:59:09.003+02:00According to general relativity there are no inert...According to general relativity there are no inertial frame of references in this universe. Therefore the first postulate of special relativity is false or irrelevant.<br /><br />This means that special relativity in non-inertial frames of reference reduces to be as aether theory, because whenever we are calculating anything with special relativity — especially if we calculate accelerations — we must select a preferred frame of reference. <br /><br />This is the reason, why Einstein and Lorentz called general relativity as aether theory, because the curvature of space-time acts as fixed frame of reference. And if we consider this fact that in general relativity all inertial frames of references are free falling, we have special relativity that is mathematically equivalent to Lorentz's aether theory. And therefore Einstein summarized this in 1920: "<i>According to the general theory of relativity space without aether is unthinkable</i>".<br /><br />Therefore when we are discussing relativistic quantum mechanics, actually it is Lorentz-relative quantum mechanics. This is very curious quirk of the history of science that Lorentz's actual contribution for special relativity is undermined. We should talk on Lorentz-Einstein Special Relativity. <br /><br />This was also Lee Smolin's notation that time is physical not relative, because according to general relativity the curvature of space-time determines the time dilation, not relative motion.<br /><br />Therefore, special relativity is logically consistent theory if we define motion as relative, but according general relativity there is no such thing as relative motion, but the orbit of GPS satellite defines the steady geodesic motion of satellite. Therefore the first postulate, principle of relativity is not required when deriving special relativity. This does not change the mathematics of SR, but this indeed changes the philosophical interpretation of the equations of special relativity, because without principle of relativity postulate, special relativity is an aether theory.<br /><br />Therefore to summarize Smolin's point: as special relativity postulate requires motion to be defined as relative, but the symmetry of relative motion is always broken due to (potential) curvature of space-time, this means that the time dilatation is always absolute and hence there exist preferred frame of reference. This preferred frame of reference is the curvature of space-time and this is exactly what Lorentz and Einstein found out from general relativity in 1916. <br /><br />Therefore claiming such renowned physicist as Smolin as a "crackpot" it just undermines your own credibility and it more or less proves that you are ignorant on the history of science. But I do not blame you as in popular literature theory of relativity is taught pedagogically wrong way. We should emphasis with special relativity and relativistic quantum mechanics Lorentz's work where emphasis the role of Einstein with general relativity. This would make it easier to understand what theory of relativity actually is. <br /><br />Mathematics in physics is useless, if you do not know what is the deep philosophical meaning of mathematics.Jouni Valkonennoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-45744690008645673762013-09-09T15:45:23.850+02:002013-09-09T15:45:23.850+02:00Dear NumCracker, that's surely true - and impo...Dear NumCracker, that's surely true - and important - that the particle content in gravity depends on the observer. It's both the point of the equivalence principle and the diffeomorphism symmetry: the separation to the "normal vacuum" and the "deviation of the real state from the vacuum, because of a field etc." is pretty much arbitrary, up to the observer's choices.<br /><br /><br />This gets amplified in the quantum theory where even the vacuum depends on which Hamiltonian we consider - the Bogoliubov transformation, Unruh radiation etc. follow.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-18655837956282201942013-09-09T15:22:52.128+02:002013-09-09T15:22:52.128+02:00However, you can not localize a graviton, therefor...However, you can not localize a graviton, therefore the particle content of your gravitational description depends on the observer! This amazes me because I thought that once GR has general covariance the number of its particle excitations would be described in the same way (but seems it can't) ... so, a free falling observer irradiates gravitational waves, but (s)he will never be allowed to know that!NumCrackernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-37061489746634833792013-09-09T11:37:03.690+02:002013-09-09T11:37:03.690+02:00I'm a crazy hack, but it should be obvious tha...I'm a crazy hack, but it should be obvious that gravitons arise because we require that eigenvalues associated with local changes in geodesics be countable. e.g. in the local reference frame where an observer is following a geodesic, their local spacetime appears 4d minkowski, but a change in the geodesic would appear as a discrete jump in response to a exchange of a particle. At microscopic levels, spacetime itself changes dimensions, so there is a definite energy scale when where our local frame can no longer be treated as 4d minkowski spacetime. This natural change in underlying metric serves to provide a perceived frame-dependence of gravitons, and all graviton modes must be viewed with respect to this fundamental scale.anonynoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-25413397163412967682013-09-09T08:25:44.333+02:002013-09-09T08:25:44.333+02:00If there is one thing you cannot get rid of in str...If there is one thing you cannot get rid of in string theory then that's a graviton! ... (well, there are other things too, but this one... yeah, well...) and you can get it from linearized GR too but that doesn't mean they are eliminated if you take into account true real gravity... quite the opposite...Andrei Patrascunoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-48869845582811508192013-09-09T07:22:13.450+02:002013-09-09T07:22:13.450+02:00I am curious how you measure the "modernity&q...I am curious how you measure the "modernity" of a viewpoint? Is it the one taken by the latest PhD that was "thrown" at a problem? Also, it does not seem to me that the method of "throwing PhDs at problems" has been particularly effective in solving many major ones in either mathematics or physics.lucretiusnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-89195794584375002052013-09-09T07:14:42.072+02:002013-09-09T07:14:42.072+02:00Dear Tom, I am not disagreeing with the "oth...Dear Tom, I am not disagreeing with the "other view" that SR is GR in flat space. I am just saying it's not particularly deep. It's like saying "special relativity without SU(3) gauge fields is like Yang-Mills theory where you demand SU(3) gauge fields to be set to zero". When interpreted strictly, it is an innocent tautology. When analyzed for in-between-the-lines messages, it wants to mislead the reader into thinking that the latter theory in the sentence must be the starting point.<br /><br /><br />Everyone who thinks that gravitons don't exists is a full-fledged crank.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-1355880916427248902013-09-09T03:57:11.357+02:002013-09-09T03:57:11.357+02:00Amazing! So the very existence of gravitons is a f...Amazing! So the very existence of gravitons is a frame-dependent (non-covariant) concept ... thanks for answering ;-)NumCrackernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-72439905621726576852013-09-08T23:52:17.155+02:002013-09-08T23:52:17.155+02:00Lubos, there is a perfectly good way to calculate ...Lubos, there is a perfectly good way to calculate the effects of gravity without gravitons, namely GR. <br /><br /><br />One only needs gravitons to make the obviously silly standard model of duck tape and hard wired constants look slightly less messy.tomandersennoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-21313600184509587162013-09-08T23:49:26.310+02:002013-09-08T23:49:26.310+02:00Lubos - you state that GR is just another theory t...Lubos - you state that GR is just another theory that happens to agree with SR. This works well for someone who believes in strings/QFT/gravitons, etc. <br /><br />What if the other view is correct - that SR is just GR in flat space? If that is the case then every theory would have to work with GR, and gravitons don't exist. This to me seems the most modern viewpoint. <br /><br />Indeed, its been shown by the thousands of PhDs thrown at the problem that building GR from gravitons is at best impossible. (The worst case scenario is that this effort was an obviously ridiculous waste of time. )<br /><br />QM and particle physics are written in terms of Newtonian dynamics and a cartesian world view. These theories were then altered to be SR compatible, sometimes without much effort or added complexity, but often with extra baggage. <br /><br />Its time to give up on linear, old school Newtonian physics and start to come up with ways of building everything out of GR - a task that has had only a few dozen PhDs worth of effort thrown at it.tomandersennoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-22288743448075040662013-09-08T17:22:58.053+02:002013-09-08T17:22:58.053+02:00The equivalence principle says that inertia is *eq...The equivalence principle says that inertia is *equivalent* to gravity, that's why it's called the "equivalence" principle.<br /><br /><br />So if you ever construct a description of inertial forces that uses virtual particles, it's of course gravitons, by the equivalence principle!Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-12755419897254083942013-09-08T16:09:30.445+02:002013-09-08T16:09:30.445+02:00Dear Lubos, if one takes equivalence principle as ...Dear Lubos, if one takes equivalence principle as really serious at microscopic level ... what should be the quanta of "inertial forces"?NumCrckernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-976652098327973172013-09-08T15:16:39.610+02:002013-09-08T15:16:39.610+02:00To new readers of this blog: that was not what I w...To new readers of this blog: that was not what I wrote over Sabine's blog, as anyone can go there and verify.Christine Cordula Dantasnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-73713588595182671052013-09-08T11:38:40.948+02:002013-09-08T11:38:40.948+02:00If you like gravitons then you should love my FTEP...If you like gravitons then you should love my FTEPs (Force Transfer Ether Particles) ;-) That ether word has nothing to with the old ether concept.<br /><br />http://toebi.com/documents/ToEbi.pdfKimmo Rouvarihttp://www.toebi.com/blog/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-4357000991750142013-09-08T10:12:09.434+02:002013-09-08T10:12:09.434+02:00Hi, if you ask why there have to be gravitons, see...Hi, if you ask why there have to be gravitons, see e.g.<br /><br />http://motls.blogspot.cz/2012/01/why-semiclassical-gravity-isnt-self.html?m=1<br /><br />Search for:<br /><br />Some people doubt that there are gravitons. But these doubts are silly.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-87009993433171199682013-09-08T06:43:38.303+02:002013-09-08T06:43:38.303+02:00Dear Lubos
I have long puzzled the gravity quest...Dear Lubos <br /><br />I have long puzzled the gravity question, Why must gravity something exchange between two particles, why must there be a gravity particle. Instead why isn't gravity just the distortion of space time where a particle with mass always distorts space time making the path to the particle always downhill. The same for something moving the movement<br />since the movement would also stretch space time also. That way the effect look the same since they are the same. I assume someone else has proposed this and it been proven wrong. Being math cripple I cannot begin to even do any math one way or another to prove to disprove my question, but that would solve a lot of problems since they would be no promulgation problems since the stretching would just be. No need of something to traverse space. The way Gravity<br />would be how mass affects space time rather than something traversing space between objects that have mass.Mark Luhmannoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-61961890265624227092013-09-08T06:23:40.584+02:002013-09-08T06:23:40.584+02:00Dear Steve, the motor is obviously "behind th...Dear Steve, the motor is obviously "behind the wall" of a room with no windows so the astronaut can't measure its fuel consumption. It's an external factor outside the lab which can't be observed in the lab so its detailed history - which must of course be different than on Earth to achieve the acceleration - doesn't violate the equivalence principle.<br /><br /><br />Also, in any real situation, one ultimately runs of fuel. This doesn't violate the equivalence principle, either. The principle doesn't say that the rocket doesn't run out of fuel. It says that *if* and *when* the rocket keeps constant acceleration, all the observation done inside will be the same as on Earth. <br /><br /><br />There's also no violation in the fact that the observer will see differently red/blue-shifted photons from the two labs. The equivalence principle applies to observations done locally in the lab only. I have discussed this point explicitly in the blog entry above, too. Too bad you didn't try to read it.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-82545584308858586282013-09-08T06:18:16.832+02:002013-09-08T06:18:16.832+02:00Dear Kashyap, it's mainly here
http://motls.b...Dear Kashyap, it's mainly here<br /><br />http://motls.blogspot.cz/2010/08/why-and-how-energy-is-not-conserved-in.html?m=1Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-82767943346031165032013-09-08T00:37:42.950+02:002013-09-08T00:37:42.950+02:00Dear Lubos:
I have always been confused about one ...Dear Lubos:<br />I have always been confused about one aspect of the equivalence principle. I am thinking about two scientists locked away in their labs, (no windows) one is on earth and the other is on a spaceship accelerating into deep space @ 9.8 m/s2. Neither scientist knows whether he is on earth or the spaceship. After a long career doing experiments aboard the spaceship, a great deal of energy has been expended, and he is moving really really fast. If the scientist on the spaceship keeps a daily record of his fuel use, (and the earthbound scientist similarly notes he is using NO fuel) how does this information remain in conformance with the equivalence principle? <br /><br /><br />If at the end of 50 years, say, both scientists were to send a beam of light to an observation point in deep space, my understanding is that the beam from earth would be redshifted (slightly?) as it climbs out of the gravitational field of the earth. On the other hand, the beam from the spaceship might arrive either redshifted or blue shifted depending on its velocity relative to the deep space observer. The part I find a bit perplexing is that the gravitational redshift just appears to be a function of the earths gravitational acceleration, but the redshift (or blueshift) from the spaceship would seem to be a function of its acceleration AND delta time. <br /><br /><br />And regarding cosmological considerations, such as Hubble's observation of the expanding universe, is the gravitational redshift very minor or negligible in comparison? <br /><br /><br />I guess the basis of my confusion is that I don't really understand what has become of all the energy (apparent energy?) that has caused me to experience 9.8 m/s2 over the last 50 years. (or is this just the sum of the food energy I've consumed over this period?)<br /><br /><br />Anyway, its been nearly 30 years since I've studied these things as an undergraduate.Steve Rnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-65532073761064588062013-09-07T22:56:05.225+02:002013-09-07T22:56:05.225+02:00Dear Lubos:
You might have seen controversy in som...Dear Lubos:<br />You might have seen controversy in some other blogs about conservation of energy in GR. What is your opinion?. If you have discussed this before just give me reference. Thanks.kashyap vasavadanoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-14042956374606321762013-09-07T21:35:13.166+02:002013-09-07T21:35:13.166+02:00The Levy-Leblond paper is really very nice. Only h...The Levy-Leblond paper is really very nice. Only high school maths but very enjoyable and enlightening. Thanks.lucretiusnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-76189292824390655342013-09-07T19:50:05.247+02:002013-09-07T19:50:05.247+02:00Note that strictly speaking you also need homogene...Note that strictly speaking you also need homogeneity and isotropy to derive SR from the two postulates. But then it turns out that the constancy of speed of light can be dropped. And it can be shown that the only two allowed transformations are either Galileo or Lorentz. Luboš, did you know about this fact? For more details, see e.g. Levy-Leblond, J.-M. (1976). One more derivation of the Lorentz transformation. American Journal of Physics, 44(3), 271–277.Ondřej Čertíkhttp://ondrejcertik.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-63178428056450495002013-09-07T19:15:28.114+02:002013-09-07T19:15:28.114+02:00Following the discussion here, I think it would be...Following the discussion here, I think it would be very interesting to see how theories developed and what were the mistakes made by the developers (well, not the technical mistakes, I mean the conceptual mistakes)... It would be interesting to see why previous attempts did not work, what the problems are etc. and why this and no other theory must be the correct one :) (not referring only to GR...)Andrei Patrascunoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-89483369471546786242013-09-07T19:01:12.773+02:002013-09-07T19:01:12.773+02:00Dear NumCracker, you would have to be more specifi...Dear NumCracker, you would have to be more specific what's your theory and what's the inconsistency you want to find out.<br /><br /><br />The only viable theory of teleparallel gravity is completely equivalent to GR and the Abelian gauge group is exactly the group of diffeomorphisms I discussed in this very article!<br /><br /><br />But it's important that it is not a Yang-Mills group - the conserved charges aren't Lorentz scalars but Lorentz vectors (the energy-momentum vector).<br /><br /><br />There are lots of wrong theories with torsion etc. This is a long and messy history because teleparallelism started as a failed attempt of Einstein before GR. A version of it is equivalent to GR, others are not and they're still failing.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.com