Question about gravity
in [Physics]
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From: "Juan R." González-Álvarez on 15 Mar 2010 11:32 "Juan R." González-Álvarez wrote on Mon, 15 Mar 2010 15:29:34 +0000: > Yousuf Khan wrote on Mon, 15 Mar 2010 10:14:31 -0400: > >> MicroTech wrote: >>> Can someone in this forum please help me sort out a confusing issue? >>> >>> Many scientists (including Einstein) claim that gravity is not a >>> force, but the effect of mass on the "fabric of spacetime". Many other >>> scientists refer to gravity as one of the four fundamental >>> interactions (three, if one considers the unification of the weak and >>> electromagnetic interactions, the "electroweak" force). >>> >>> Adding to the confusion, some scientists use both concepts with no >>> apparent difficulty: >>> Stephen Hawking (in his "A Brief History Of Time") first says that >>> gravity is not a force, but "simply" the effect of mass on the >>> "spacetime fabric" (making it "curve"). However, later in the book, he >>> refers to gravity as a fundamental force, carried by the graviton. >>> >>> So what is gravity, "really"? Does anybody really know? Or do we just >>> know its effects? >> >> The Einstein description of gravity is the only one that's been proven >> at some level. > > This is plain wrong. All the observations verified by General relativity > are also satisfied with other theories also: > > # Reflections on Gravity 2000: arXiv:astro-ph/0006423v1. Straumann, > Norbert. > > # Field Theory of Gravitation: Desire and Reality 1999: > arXiv:gr-qc/9912003v1. Baryshev, Yurij, V. > > # On a possibility of scalar gravitational wave detection from the > binary pulsar PSR 1913+16 1999: arXiv:gr-qc/9911081v1. Baryshev, Yurij, > V. > > # A Hamiltonian approach to quantum gravity 2008: > arXiv:physics/0612019v9. Stefanovich, Eugene V. > > # Nonlocal forces of inertia in cosmology 1996: Found. of Phys. 26(2), > 271—283. Assis, André K. T.; Graneau, Peter. Oooops. No, this reference by Assis and Graneau is wrong and fails experimental tests. Forget about it :-D > # Gravitational interaction in the relational approach 2008: Grav. and > Cosm. 14(1), 41—52. Vladimirov, Yu. S. > > I do not know the experimental status of teleparallelism, but my belief > is that also explains the same tests than general relativity does > > http://en.wikipedia.org/wiki/Teleparallelism > >> Not all aspects of Einstein's theory have been proven yet (e.g. gravity >> waves), but a large amount of it is has. So it is the only description >> of gravity that has passed beyond the stage of theory into a law of >> physics. > > Plain wrong again as showed above. > > Moreover, Feynman taugh the field theoretic approach in Caltech for > years. And Schwinger and Weinberg did something similar. > >> The description of gravity as a force particle, the graviton, is part >> of a next generation theory of quantum mechanics known as >> Supersymmetry. > > Nonsense. Gravitons have nothing to see with speculative supersymmetry. > Your supersymmetry is "the next generation theory of quantum mechanics" > is another nonsensical statement. > >> Supersymmetry is part of a larger next generation framework theory >> called Superstring Theory, and now M-Theory. > > Both build over rather standard and outdated quantum formalism. The next > generation of quantum mechanics is becoming from other camps > > "The Liouville Space Extension of Quantum Mechanics" 1996: Advances in > Chemical Physics XCIX, 1-120. Petrosky T; Prigogine, Ilya. > > A generalized quantum mechanics beyond their work is under active > research now > > http://www.canonicalscience.org/research/research.html > > http://www.canonicalscience.org/research/canonical.html > > http://www.canonicalscience.org/research/time.html > >> None of the aspects of these next-gen theories have been proven yet. > > They were believed to be next-gen theories about 20 or 30 years ago... > Today we know that both superstring and M-theories are dead and plain > wrong. > > The future of physics will be leaded by other theories, with > superstrings and M-theory reminder as one of greates fiascos of physics. > > There is excellent textbooks about this, for instance > > The Trouble With Physics: The Rise of String Theory, the Fall of a > Science, and What Comes Next > > http://www.amazon.com/Trouble-Physics-String-Theory-Science/dp/0618551050 > > (Further nonsenses and sci-pop claims snipped) -- http://www.canonicalscience.org/ BLOG: http://www.canonicalscience.org/publications/canonicalsciencetoday/canonicalsciencetoday.html
From: Sue... on 15 Mar 2010 11:39 On Mar 15, 2:42 am, MicroTech <henry.ko.nor...(a)gmail.com> wrote: > Can someone in this forum please help me sort out a confusing issue? > > Many scientists (including Einstein) claim that gravity is not a > force, but the effect of mass on the "fabric of spacetime". Many other > scientists refer to gravity as one of the four fundamental > interactions (three, if one considers the unification of the weak and > electromagnetic interactions, the "electroweak" force). Force terms exist but they become unwieldy (and probably unnecessay) as the relations are converted to geometrical terms. It is not too difficult to follow some "vestiges" of the Coulomb force here: http://farside.ph.utexas.edu/teaching/em/lectures/node127.html > > Adding to the confusion, some scientists use both concepts with no > apparent difficulty: > Stephen Hawking (in his "A Brief History Of Time") first says that > gravity is not a force, but "simply" the effect of mass on the > "spacetime fabric" (making it "curve"). However, later in the book, he > refers to gravity as a fundamental force, carried by the graviton. > > So what is gravity, "really"? Does anybody really know? Or do we just > know its effects? This is as good as anything else 'till someone catches a Higgs or a gravity wave. Emergent gravity http://relativity.livingreviews.org/Articles/lrr-2005-12/articlesu25.html#x34-720006.3 http://en.wikipedia.org/wiki/Induced_gravity Sakharov's induced gravity: a modern perspective http://arxiv.org/abs/gr-qc/0204062 The Origin of Gravity Authors: C. P. Kouropoulos http://arxiv.org/abs/physics/0107015 http://arxiv.org/abs/physics/0107015v1 Sue... > > Is it an attractive force "mutually pulling" the Earth towards the Sun > (and vice versa), "causing" the Earth to "fall" towards the Sun? And > due to the "forward motion" of the Earth, exactly matching the > "gravitational pull", it stays in orbit (just like any other > satellite, man-made or not); OR > > Is it the mass of the Sun that "curves spacetime", so no force is > interacting with the Earth, it is just moving in a "straight line" > along a "curved spacetime" geodesic? > > At my current level of understanding, gravity should be one or the > other, and not both... > > If Einstein's concept of "curved spacetime" is "correct," where does > the (hypothetical?) "graviton" (and/or "gravitino") enter the picture? > > References to published papers (accessible online) would be much > appreciated! > > Henry Norman
From: Inertial on 15 Mar 2010 10:09 "kenseto" <kenseto(a)erinet.com> wrote in message news:09cf23d5-351a-4602-adce-f4cfbf00034c(a)a18g2000yqc.googlegroups.com... > On Mar 15, 6:43 am, "Peter Webb" > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: >> Not a whole lot to add to what Inertial in particular said. >> >> In GR, gravity is a virtual force in a similar way to centrifugal force >> in >> Newton. In both cases its really an acceleration, and the force is just >> the >> product (literally) of this acceleration and the mass of the object. >> >> Einstein in GR gave a geometric interpretation of what gravity is. This >> is >> very appealing, because it provides a mechanism for force at a distance. > > Wrong it provides no such physical mechanism. It merely assumes the > existence of a physical entity caLLED the fabric of spacetime for the > interacting object to follow. Its just how things move. There no more need for there to be a 'physical entity' (and certainly not a material one) for that to happen, than there needs to be one in 3D Newtonian/Euclidean/Gaillean space to make objects follow a straight line (ie follow Newton's first law) > The problem with such assumption is: > What is the fabric of spacetime physically? This question is relevant > because SR/GR deny the existence of physical space. What do you mean by 'physical space'
From: Inertial on 15 Mar 2010 10:26 "kenseto" <kenseto(a)erinet.com> wrote in message news:6da9016c-0250-416b-8e16-0edcd9a1a626(a)r27g2000yqn.googlegroups.com... > On Mar 15, 9:16 am, Huang <huangxienc...(a)yahoo.com> wrote: >> > > Can someone in this forum please help me sort out a confusing issue? >> >> > > Many scientists (including Einstein) claim that gravity is not a >> > > force, but the effect of mass on the "fabric of spacetime". Many >> > > other >> > > scientists refer to gravity as one of the four fundamental >> > > interactions (three, if one considers the unification of the weak and >> > > electromagnetic interactions, the "electroweak" force). >> >> Einstein is correct, that gravity can be regarded as curvature or >> deformation of space. Other views are equivalent to this model, such >> as the view that gravity is a force. These two approaches are >> equivalent in my opinion. >> >> The pieces which are missing in this puzzle: >> [a] Explaining strong force in terms of spacetime curvature, >> [b] Explaining weak force in terms of spacetime curvature, >> [c] Explaining electromagnetism in terms of spacetime curvature. >> >> When a,b,c have been explained in terms of spacetime deformation, and >> are shown to be equivalent to the particle explanations of a,b,c, then >> you will be very close to grand unification. > > a, b, c can be explained with a special aether called the E-Matrix in > place of the none physical existence of spacetime in the following > link: > http://www.modelmechanics.org/2008irt.dtg.pdf Total bullshit
From: PD on 15 Mar 2010 13:22
On Mar 15, 1:42 am, MicroTech <henry.ko.nor...(a)gmail.com> wrote: > Can someone in this forum please help me sort out a confusing issue? > > Many scientists (including Einstein) claim that gravity is not a > force, but the effect of mass on the "fabric of spacetime". Many other > scientists refer to gravity as one of the four fundamental > interactions (three, if one considers the unification of the weak and > electromagnetic interactions, the "electroweak" force). > > Adding to the confusion, some scientists use both concepts with no > apparent difficulty: > Stephen Hawking (in his "A Brief History Of Time") first says that > gravity is not a force, but "simply" the effect of mass on the > "spacetime fabric" (making it "curve"). However, later in the book, he > refers to gravity as a fundamental force, carried by the graviton. > > So what is gravity, "really"? Does anybody really know? Or do we just > know its effects? > > Is it an attractive force "mutually pulling" the Earth towards the Sun > (and vice versa), "causing" the Earth to "fall" towards the Sun? And > due to the "forward motion" of the Earth, exactly matching the > "gravitational pull", it stays in orbit (just like any other > satellite, man-made or not); OR > > Is it the mass of the Sun that "curves spacetime", so no force is > interacting with the Earth, it is just moving in a "straight line" > along a "curved spacetime" geodesic? > > At my current level of understanding, gravity should be one or the > other, and not both... > > If Einstein's concept of "curved spacetime" is "correct," where does > the (hypothetical?) "graviton" (and/or "gravitino") enter the picture? > > References to published papers (accessible online) would be much > appreciated! > > Henry Norman It's definitely a different kind of animal. Part of the issue is understanding better what it is the particle represents. For example, in electromagnetism, the classical picture is a field in the background of space and time. The particle is a quantization of disturbances in that field in the background of space and time. Here, the field IS space and time itself, not in a background of space and time. And the particle would be a quantization of a disturbance in space and time itself, not a disturbance of a field in the background of space and time. The naive (but appealing) view of the electromagnetic quantum is something that moves *through* the background of time and space. The gravitational quantum isn't quite like that, as it is not really moving *through* the background of time and space, but is more closely tied to space and time itself. It's interesting that some of the more promising candidates for quantum gravity are "backgroundless" in that they do not assume a space and time through which gravitons move. Instead, space and time themselves arise from the interactions of the quanta. This makes my head hurt a little, but it does look promising. PD |