I decided to start another column, for this is getting too nested. The link is:

http//www.sciencedaily.com/releases/2011/06/110630111540.htm

where sometimes if links are embedded there is a http://%20 automatically put in front of the address which screws it up. These results are serious game changers, and a lot of theory may be headed for the paper shredder as a result.

Special relativity is so central to physics these days that there are really no question with respect to its basic form and applicability in its appropriate domain of observation. General relativity is still a subject of research. In the Parameterized Post-Newtonian (PPN) formalism general relativity has been supported by data out to second order. The third order involves weak gravity waves. The Hulst-Taylor observation of pulsar orbital period change supports indirectly the existence of gravity waves, but gravity waves have yet to be directly detected.

The arrow of time problem, assuming it really is a problem, may involve some CP violating mechanism. The discrete symmetry CPT = 1 C = charge conjugation, P = parity change, T = time change, with ψ = ψ_q(r, t) (q = charge, r = position and t = time) acts as:

Cψ_q(r, t) = ψ_{-q}(r, t)

Pψ_q(r, t) = ψ_q(-r, t)

Tψ_q(r, t) = ψ_q(r, -t).

Then CPTT = CP = T, and if CP is violated then T is violated. That TT = T^2 = 1 is easily seen by how it acts on a wave-field above. A CP violation would then mean there is some underlying breaking of chiral symmetry which underlies gravitation. A chiral breaking on CP is then equivalent to the breaking of time symmetry with T.

Cheers LC

    What we perceive as the flow of time is, in reality, nothing more and nothing less than the evolution of the physical universe, an evolution which is governed by rules which we strive to understand and which we refer to as the laws of physics. This view is fully consistent with Ellis' concepts of a crystallizing block universe and free will. As sentient beings, we are able not only to perceive the ongoing evolution of the universe around us, but also, by our own actions, to influence that evolution, albeit in limited fashion.

    When viewed from this perspective a causal arrow of time is inevitable, as is discussed further here and here.

    Best,

    jcns

      "Then CPTT = CP = T, and if CP is violated then T is violated. That TT = T^2 = 1 is easily seen by how it acts on a wave-field above. A CP violation would then mean there is some underlying breaking of chiral symmetry which underlies gravitation. A chiral breaking on CP is then equivalent to the breaking of time symmetry with T."

      An expert summary, Lawrence, as usual.

      I find CP violation equivalent to scale invariant information loss, as described mathematically in my 2008 FQXi essay, and my "time barrier" preprint, applying complex analysis to Kepler's classical second law of orbital motion.

      This works, by giving the time metric a specifically physical definition requiring n-dimension infinite orientability (and therefore, a Hilbert space domain of infinite range).

      Tom

      LC,

      http://www.sciencedaily.com/releases/2011/06/110630111540.htm reminds me of a predicted impossibility to discover more galaxies. Admittedly, I did not wonder if there was no limit of resolution at all. Is there any compelling reason to consider space and time grained?

      Eckard

      Eckard,

      You raise a good point. I have always been personally uncomfortable with the "block time" and/or "block universe" concept and terminology. As discussed in this FQXi article, however, I can coexist with it. I take Ellis' "crystallization" to represent the evolution of the physical universe from previous configurations into the current configuration (i.e., "the present,") which, in turn, will evolve into yet other configurations which we refer to as "the future." These hypothesized future configurations, unlike the configurations which we refer to as "the past," have never been objectively real.

      I can accept that someone might consider the set of all previously objectively real configurations as constituting an unchangeable "block" of past reality, despite the fact that those past configurations are not now objectively real. Future configurations, on the other hand, are not determined, nor can they be, due to the impossibility of precisely knowing their initial conditions. This leaves the future open to to the possibility of being influence by any number of factors, including by sentient beings such as ourselves. Unfortunately, the long-term consequences of such influences also cannot be predicted.

      This comes down to the long-ongoing Heraclitean vs. Parmeidean debate; i.e., between "presentism" and "eternalism." I side strongly, of course, with Heraclitus in this debate.

      Best,

      jcns

      jcns,

      Einstein followed Spinoza who equated nature and God, which are both imagined to be inexhaustible. With respect to such original meaning of infinity, I consider Spinoza correct but Cantor and Zermelo wrong. On the other hand, I do not see any justification in science for religious eternalism, rebirth and fatalism. Zeno's defense of Parmenides looks ridiculous to me. Einstein put himself outside science when he did not object to Popper who called him a Parmenidean and even more when he uttered that for him as a believing physicist the distinction between past, present, and future is just an obstinate illusion.

      Unfortunately, SR and spacetime have been based on this denial of necessary in reality distinctions between past and future as well as reality and theory. I do not yet see my position represented in old debates, neither in presentism nor in eternalism. I am arguing that the concrete future can never be completely modeled for sure. Closed systems are idealizations.

      Regards,

      Eckaed

      The graininess of spacetime is because of quantum fluctuations. If I invoke the Heisenberg uncertainty principle ΔEΔt = ħ and use E = mc^2 there is then a fluctuation of mass given by Δm = ħ/Δtc^2. The uncertainty in time is and uncertainty in position Δt = Δr/c so that Δm = ħ/Δrc, and a metric δg_{00} = 1 - 2Għ/(rΔr c^3), where the metric radius r >> Δr.

      Now let the length uncertainty be Δr ~ L_p = sqrt{Għ/c^3}, and we substitute this into the metric uncertainty

      δg_{00} = 1 - 2Għ/(rL_p c^3) ~ 1 - 2L_p/r.

      This is a nice compact result. Now let the radius term be the probe length, which is given by the wavelength of the different radiation r = λ, and we assume λ >> L_p. The approximate metric for radiation of a certain wavelength is then

      ds^2 = c^2δg_{00}dt^2 - dx^2 - dy^2 - dz^2

      = c^2(1 - 2L_p/λ)dt^2 - dx^2 - dy^2 - dz^2.

      For EM radiation ds = 0 and for radiation propagating along one of the directions we have

      dx/dt = c sqrt{1 - 2L_p/λ}.

      This predicts then a wavelength dependency on the speed of light

      c' = c sqrt{1 - 2L_p/λ}

      So if radiation travels a distance D = c'T the time of travel is T = D/(c sqrt{1 - 2L_p/λ}) and I use the binomial theorem for λ >> L_p

      T ~ (D/c)(1 + L_p/λ).

      So this is the effect of quantum fluctuations, really a naïve theory of such fluctuations, should have on radiation. Clearly very short wavelength radiation is slowed down.

      The FERMI spacecraft detected gamma rays of 33GeV and much radiation at the bottom of the bandwidth at about 10^3eV from a Gamma Ray Burst event GRB 090510 out 7.3 billion light years. We can use these to estimate the time of arrival for the two forms of radiation. L_p/λ = E_γ/E_p =~ 33GeV/1.2x10^{18}GeV = 2.7x10^{-17}. For the softer gamma ray this is E_γ/E_p ~= 10^{-24}. Input this into our formula for the change in speed of light and we get

      T - T' = (D/c)( 2.7x10^{-17} - 10^{-24})

      =~ (7x10^{25}m/3x10^8m/sec) 2.7x10^{-17} = 6.7sec.

      The GRB event observed had a time spread of 2 seconds and the two photons which a 10^6 spread in energy arrived at the detector within .8 seconds. Given the error margins and so forth this puts some pretty tight constraints on the role of such fluctuations on physics.

      This type of spacetime fluctuation is basically ruled out, which are fluctuations that on a small scale violate Lorentz invariance. With heterotic string theory E_8 -- > SU(3)xE_6, which gives a twistor type of theory. Twistor theory does not invoke this sort of energy dependency on light cone structure. Rather the uncertainty is in a null congruency, but where all null rays in the bundle, such as a null plane, all have the same spacetime direction.

      Cheers LC

      LC,

      "Now let the length uncertainty be Δr ~ L_p". Doing so, don't we assume a graininess that can possibly be falsified by intelligent measurements?

      Even our ears outperform Heisenberg's uncertainty relation, see Fig. 1 in my essay. Didn't Aephraim Steinberg also overcome uncertainty when he pinpointed mean trajectories of single photons?

      Regards,

      Eckard

      This is basically how a lot of science is done, "crank 'er up and see why she don't run." The assumptions of metric fluctuations of this nature lead to this sort of dispersion, which as it turns out we do not observe.

      Cheers LC

      a month later

      Eckard Blumschein wrote: "When Einstein declared "the separation between past, present, and future an obstinate illusion" he made two horror mistakes at a time."

      From a logical point of view, the mistake is only one: his 1905 constant-speed-of-light postulate is false. So one should not reject the block universe without questioning special relativity, as Ellis does. Presentists are much more straightforward:

      http://philsci-archive.pitt.edu/2308/1/presentism_and_qg_vp_3_dd.pdf

      PRESENTISM AND QUANTUM GRAVITY, by Bradley Monton

      "I am a presentist: I believe that only presently existing things exist. Contrast presentism with eternalism: the eternalist believes that past, present, and future things all exist. Assuming that there are three spatial dimensions, the eternalist believes that the universe is fourdimensional, and while there are different events in different regions of this so-called "block universe", the universe as a whole does not change. The presentist, in contrast, believes that the universe is three-dimensional. (...) The point of this paper is not to argue for presentism, but to defend presentism from a particular type of argument that is often taken to refute it. The form of the argument is as follows:

      (1) Presentism is incompatible with relativity theory (usually the focus is on special relativity).

      (2) Relativity theory is our most fundamental theory of physics.

      (3) Presentism is incompatible with our most fundamental theory of physics. (From (1) and (2).)

      (4) Presentism is false. (From (3).)

      (...) But regardless of the strength of the arguments for presentism, the presentist is not required to endorse a non-traditional understanding of relativity. The presentist can simply say that presentism is incompatible with special and general relativity, and hence special and general relativity are false."

      ______________________________

      [end of quotation]

      How can special relativity be false? It is based on two postulates - the principle of relativity and the principle of constancy of the speed of light - so one of the postulates must be false. Which one? This is an absolute-crimestop question in Einsteiniana:

      http://www.liferesearchuniversal.com/1984-17

      George Orwell: "Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity."

      Pentcho Valev pvalev@yahoo.com

      Dear Pentcho,

      Is presentism the only alternative to eternalism? Because the notion presence is deliberately imprecise, I wonder why some people are using it in physics.

      In reality, only traces and memories from the past are presently available or even influencing. The past is distinguished since it cannot be influenced.

      To my knowledge, the speed of electromagnetic waves is limited to a constant value in vacuum as also is the speed of sound waves in a given medium. Claimed ftl propagation of signals were elusive. Electric and magnetic fields that are measurable without spatial restriction can obviously not belong to a closed local system like Galilei's boat which is the precondition for independence of velocity. For this reason, I do not exclude that Einstein's postulate of relativity is unrealistic in the real world while logically flawless on the playground of an assumed closed and tense-less system.

      I got aware of those who are proponents of deBroglie's guiding wave and neo-Lorentzian relativity.

      Regards,

      Eckard

      23 days later

      Misleading presentation of the experiment.

      In this article there is a suggestion that the detectors "placed behind the screen" somehow detect trough which slit the photons went, -detect some time after! the photons have passed the slits. But that is misleading! There are no such detectors. In the actual experiment the detection happen at the time the photons pass through the slits (before they hit the screen). Big difference.

      4 years later