tag:blogger.com,1999:blog-3904639295706642486.post3912441542231353281..comments2023-10-21T08:48:37.363-07:00Comments on Zone-Reflex: What's the Matrix? Relative locality.Unknownnoreply@blogger.comBlogger11125tag:blogger.com,1999:blog-3904639295706642486.post-79431565931749455792012-11-15T23:58:17.785-08:002012-11-15T23:58:17.785-08:00http://www.newscientist.com/article/mg21128241.700...http://www.newscientist.com/article/mg21128241.700-beyond-spacetime-welcome-to-phase-space.html<br /><br />Smolin's relevant manuscripts are:<br /><br />G. Amelino-Camelia, L. Freidel, J. Kowalski-Glikman, and L Smolin, The principle of relative locality. http://arxiv.org/abs/1101.0931<br /><br />L. Freidel and L. Smolin, Gamma ray burst delay times probe the geometry of momentum space. http://arxiv.org/abs/1103.5626<br /><br />...........So what is phase space? It is a curious eight-dimensional world that merges our familiar four dimensions of space and time and a four-dimensional world called momentum space.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-47831159826476192012012-11-15T01:24:51.150-08:002012-11-15T01:24:51.150-08:00http://www.kurzweilai.net/big-bang-or-big-chill-th...http://www.kurzweilai.net/big-bang-or-big-chill-the-quantum-graphity-theory<br />Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-35659185935368722402011-04-26T12:32:55.739-07:002011-04-26T12:32:55.739-07:00Matti has written two posts relating to this today...Matti has written two posts relating to this today.<br /><br />http://matpitka.blogspot.com/2011/04/how-arrow-of-geometric-time-is-selected.html<br /><br />http://matpitka.blogspot.com/2011/04/objection-against-zero-energy-ontology.html<br /><br />See also http://en.wikipedia.org/wiki/Flipped_SU%285%29Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-34635072182802348622011-04-17T03:40:54.829-07:002011-04-17T03:40:54.829-07:00Part II of Nimas talk.
http://online.kitp.ucsb.edu...Part II of Nimas talk.<br />http://online.kitp.ucsb.edu/online/qcdscat11/arkanihamed2/Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-85218557412246343132011-04-15T12:38:43.882-07:002011-04-15T12:38:43.882-07:00http://online.kitp.ucsb.edu/online/qcdscat11/arkan...http://online.kitp.ucsb.edu/online/qcdscat11/arkanihamed/<br /><br />Gravity + QM = spacetime is doomed!<br />Locality+Unitarity!<br /><br />Look at this!Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-79179695900567129212011-04-11T00:20:11.142-07:002011-04-11T00:20:11.142-07:00http://riofriospacetime.blogspot.com/2011/04/end-o...http://riofriospacetime.blogspot.com/2011/04/end-of-beyond-einstein.html<br /><br />The local conditions of Special Relativity, which do not allow for gravity, can be linked with the curved Space/Time of General Relativity. The solution can explain much about the Universe--its size, expansion rate and whether that expansion will stop or reverse. A bit of math can explain the non-linear increase of supernova redshifts, the cosmic horizon problem, the "flatness" problem, even the 4.507034% proportion of baryons. Long before the expensive Space missions would have launched, we may already be Beyond Einstein.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-14071839033993427062011-04-06T03:13:27.566-07:002011-04-06T03:13:27.566-07:00http://www.sciencedaily.com/releases/2011/04/11040...http://www.sciencedaily.com/releases/2011/04/110405084252.htm<br />Jiří Tomkovič, Michael Schreiber, Joachim Welte, Martin Kiffner, Jörg Schmiedmayer, Markus K. Oberthaler. Single spontaneous photon as a coherent beamsplitter for an atomic matter-wave. Nature Physics, 2011; DOI: 10.1038/nphys1961<br /><br />Standing in front of a mirror, we can easily tell apart ourselves from our mirror image. The mirror does not affect our motion in any way. For quantum particles, this is much more complicated. In a spectacular experiment in the labs of the University of Heidelberg, a group of physicists at the University Heidelberg, together with colleagues at TU Munich and TU Vienna extended a 'thought experiment' by Einstein and managed to blur the distinction between a particle and its mirror image.<br /><br />When an atom emits light (i.e. a photon) into a particular direction, it recoils in the opposite direction. If the photon is measured, the motion of the atom is known too. The scientists placed atoms very closely to a mirror. In this case, there are two possible paths for any photon travelling to the observer: it could have been emitted directly into the direction of the observer, or it could have travelled into the opposite direction and then been reflected in the mirror. If there is no way of distinguishing between these two scenarios, the motion of the atom is not determined, the atom moves in a superposition of both paths.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-10825479207214085832011-04-06T03:08:44.804-07:002011-04-06T03:08:44.804-07:00http://www.sciencedaily.com/releases/2011/04/11040...http://www.sciencedaily.com/releases/2011/04/110405161345.htm<br />Time-Delayed Jets Around Young Star<br /><br />This would confirm the varying c, AND ZEO.<br /><br />"Now we know that in at least one case, there appears to be a delay, which tells us that some sort of communication may be going on between the jets that takes time to occur."remained hidden behind a dark cloud. Spitzer's sensitive infrared vision was able to pierce this cloud, revealing the obscured jet in greater detail.<br /><br />the newfound jet is perfectly symmetrical to its twin, with identical knots of ejected material.<br /><br />This symmetry turned out to be key to the discovery of the jets' time delay. By measuring the exact distances from the knots to the star, the astronomy team was able to figure out that, for every knot of material punched out by one jet, a similar knot is shot out in the opposite direction 4.5 years later. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer . materials provided by NASA/Jet Propulsion Laboratory. http://www.jpl.nasa.gov/<br /><br />Jets are an active phase in a young star's life. A star begins as a collapsing, roundish cloud of gas and dust. By ejecting supersonic jets of gas, the cloud slows down its spinning. As material falls onto the growing star, it develops a surrounding disk of swirling material and twin jets that shoot off from above and below the disk, like a spinning top.<br /><br />Once the star ignites and shines with starlight, the jets will die off and the disk will thin out.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-2771854536845013762011-04-06T01:48:10.202-07:002011-04-06T01:48:10.202-07:00That was only an excerpt, but it clearly did not d...That was only an excerpt, but it clearly did not dismiss this idea.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-29469956208358553362011-04-06T01:47:09.218-07:002011-04-06T01:47:09.218-07:00This scale does raise a question for many people w...This scale does raise a question for many people who first hear this argument, though – that quantum gravity effects should become apparent around the Planck mass/momentum scale, since macro-objects like the aforementioned soccer ball still seem to have linearly-additive momenta. Laurent explained the problem with this intuition. For interactions of big, extended, but composite objects like soccer balls, one has to calculate not just one interaction, but all the various interactions of their parts, so the “effective” mass scale where the deformation would be seen becomes N m_p where N is the number of particles in the soccer ball. Roughly, the point is that a soccer ball is not a large “thing” for these purposes, but a large conglomeration of small “things”, whose interactions are “fundamental”. The “effective” mass scale tells us how we would have to alter the physical constants to be able to treat it as a “thing”.<br /><br />In “spacetime”, a spaceship travelling a large loop at high velocity will arrive where it started having experienced less time than an observer who remained there (because of the Lorentzian metric) – and a dual phenomenon in momentum space says that particles travelling through loops (also in momentum space) should arrive displaced in space because of the relativity of localization. This could be observed in particle accelerators where particles make several transits of a loop, since the effect is cumulative. Another effect could be seen in astronomical observations: if an observer is observing some distant object via photons of different wavelengths (hence momenta), she might “localize” the object differently – that is, the two photons travel at “the same speed” the whole way, but arrive at different times because the observer will interpret the object as being at two different distances for the two photons.<br /><br />This last one is rather weird, and I had to ask how one would distinguish this effect from a variable speed of light (predicted by certain other ideas about quantum gravity). <br /><br />Again, this is no more bizarre (mathematically) than the fact that distant, relatively moving, observers in special relativity might disagree about simultaneity, whether two events happened at the same time. They have their own coordinates on spacetime, and transferring between them mixes space coordinates and time coordinates, so they’ll disagree whether the time-coordinate values of two events are the same. Similarly, in this phase-space picture, two different observers each have a coordinate system for splitting phase space into “spacetime” and “energy-momentum” coordinates, but switching between them may mix these two pieces. Thus, the two observers will disagree about whether the spacetime-coordinate values for the different interacting particles are the same. And so, one observer says the interaction is “local in spacetime”, and the other says it’s not. The point is that it’s local for the particles themselves (thinking of them as observers). All that’s going on here is the not-very-astonishing fact that in the conventional picture, we have no problem with interactions being nonlocal in momentum space (particles with very different momenta can interact as long as they collide with each other)… combined with the inability to globally and invariantly distinguish position and momentum coordinates.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-76857281476436221732011-04-06T01:46:56.746-07:002011-04-06T01:46:56.746-07:00http://theoreticalatlas.wordpress.com/2011/03/31/r...http://theoreticalatlas.wordpress.com/2011/03/31/relativity-of-localization/<br />Various additional physical assumptions – like the momentum-space “duals” of the equivalence principle (that the combination of momenta works the same way for all kinds of matter regardless of charge), or the strong equivalence principle (that inertial mass and rest mass energy per the relation E = mc^2 are the same) and so forth can narrow down the geometry of this metric and connection. Typically we’ll find that it needs to be Lorentzian. With strong enough symmetry assumptions, it must be flat, so that momentum space is a vector space after all – but even with fairly strong assumptions, as with general relativity, there’s still room for this “empty space” to have some intrinsic curvature, in the form of a momentum-space “dual cosmological constant”, which can be positive (so momentum space is closed like a sphere), zero (the vector space case we usually assume) or negative (so momentum space is hyperbolic).<br /><br />This geometrization of what had been algebraic is somewhat analogous to what happened with velocities (i.e. vectors in spacetime)) when the theory of special relativity came along. Insisting that the “invariant” scale c be the same in every reference system meant that the addition of velocities ceased to be linear. At least, it did if you assume that adding velocities has an interpretation along the lines of: “first, from rest, add velocity v to your motion; then, from that reference frame, add velocity w”. While adding spacetime vectors still worked the same way, one had to rephrase this rule if we think of adding velocities as observed within a given reference frame – this became v \oplus w = (v + w) (1 + uv) (scaling so c =1 and assuming the velocities are in the same direction). When velocities are small relative to c, this looks roughly like linear addition. Geometrizing the algebra of momentum space is thought of a little differently, but similar things can be said: we think operationally in terms of combining momenta by some process. First transfer (group-valued) momentum p to a particle, then momentum q – the connection on momentum space tells us how to translate these momenta into the “reference frame” of a new observer with momentum shifted relative to the starting point. Here again, the special momentum scale m_p (which is also a mass scale since a momentum has a corresponding kinetic energy) is a “deformation” parameter – for momenta that are small compared to this scale, things seem to work linearly as usual.<br /><br />There’s some discussion in the paper which relates this to DSR (either “doubly” or “deformed” special relativity), which is another postulated limit of quantum gravity, a variation of SR with both a special velocity and a special mass/momentum scale, to consider “what SR looks like near the Planck scale”, which treats spacetime as a noncommutative space, and generalizes the Lorentz group to a Hopf algebra which is a deformation of it. In DSR, the noncommutativity of “position space” is directly related to curvature of momentum space. In the “relative locality” view, we accept a classical phase space, but not a classical spacetime within it.<br /><br />We should understand this scale as telling us where “quantum gravity effects” should start to become visible in particle interactions. This is a fairly large scale for subatomic particles. The Planck mass as usually given is about 21 micrograms: small for normal purposes, about the size of a small sand grain, but very large for subatomic particles. Converting to momentum units with c, this is about 6 kg m/s: on the order of the momentum of a kicked soccer ball or so. For a subatomic particle this is a lot.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.com