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The Planck Scale: Gravity’s Ultimate Limit?
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Blogger Mark Wyman wrote on Aug. 1, 2010 @ 21:07 GMT
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Scientific researchers, especially younger ones dreaming of glory and fame, are generally averse to setting boundaries and claiming absolute limits. This stems both from a hopefulness that Nature will be kind enough to give us plenty of new secrets to unravel in the future as well as an anxiety about ending up later as the villain in a just-so story about how the “establishment” naively criticized a new theory when it first appeared. In light of this, it’s always notable when researchers find a new way of stating just how limiting the laws we know are. A very fine example of this kind of work appeared recently on the arXiv, in a paper by Gia Dvali and Cesar Gomez,
Self-Completeness of Einstein Gravity.
This paper rains on the parade of those who hope against hope that there will be a fundamental theory of gravity with a regime of validity that pierces the Planck length. The Planck length is the smallest length scale presently contemplated in all of Physics: it is the length scale where gravity becomes as strong as the other fundamental forces. General relativity (GR) predicts that any experiment with enough energy to probe the Planck length must necessarily form a black hole in the process, thwarting the ability of the experiment to send out any results describing what happened on shorter length scales. What we’re not sure of is whether GR is right about this.
Dvali and Gomez’s paper is a subtle and powerful argument that GR is correct on this point: they pull together a variety of lines of reasoning to this effect, but the central claim and most powerful claim is that there is, in effect, _no_ _difference_ between the super-high energy physics inside the Planck length and well-known black hole physics. The idea is this: the way gravity works is that it wraps a black hole horizon around any region of space that reaches Planckian energy-densities. This black hole is a kind of buffer that absorbs the huge energy density, converting it into the relatively slower moving physics of black holes, where the energy will leak out later in the form of Hawking radiation. In other words: the Planck length also sets a minimum time scale in nature, a Planck time, faster than which nothing can occur. If an event is set to occur more quickly than this time, it get bounced or reflected by gravity into a black hole that flips that fast moving event into a slower-moving black hole horizon. The bigger the energy, the bigger the resulting black hole, and hence the _longer_ it takes for the energy to escape as Hawking radiation.
If true, this means that the real locus of our hope for novel physics is the Planck length itself. A black hole that just barely has enough energy to form evaporates most quickly. If we could see such a thing happen, we could get a window into the ultimate energy scale of physics. However, such a black hole is far beyond the scope of our most powerful Earth-based accelerators: it is fifteen _orders_ _of_ _magnitude_ smaller than the length scales that the Large Hadron Collider’s record-breaking collisions will probe, for instance. (Ie, to get to the Planck length, you’d need an accelerator 1,000,000,000,000,000 times more powerful than the LHC!). So it remains a big open question as to whether Dvali and Gomez’s ideas will ever be tested. In the meantime, we will have plenty of opportunity to explore whether there are any sneaky ways to get around their arguments; and you can count on it that many researchers are already looking to do just that, if they can!
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John Merryman wrote on Aug. 1, 2010 @ 23:49 GMT
Uh, what does this say about Inflation Theory? Wouldn't the universe collapse back into the singularity and not expand out at many times the speed of light, to a size much larger than the visible universe?
"The idea is this: the way gravity works is that it wraps a black hole horizon around any region of space that reaches Planckian energy-densities."
Surely there must have been "Planckian energy-densities" in that first moment after the singularity popped into existence!
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The Lightbringer replied on Aug. 7, 2010 @ 19:55 GMT
Inflation theory only works because the self represents, forms, and experiences a comprehensive approximation of the totality of experience by combining unconscious and conscious experience. Inflation theory relates, accordingly, to our growth and development, yet it is garbage all the same.
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Lawrence B. Crowell wrote on Aug. 2, 2010 @ 00:21 GMT
I have not read the Dvali Gomez paper yet. However, the UV/IR correspondence does pretty clearly indicate that the Planck scale is an hard cut off with measurable physics.
Chers LC
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T H Ray replied on Aug. 2, 2010 @ 11:54 GMT
I agree, Lawrence. Einstein (classical) gravity and string theory are non-separable in my own model as well, in that the parabolic projections of n-dimension kissing spheres bounding the hyperbolic space of string theory make Einstein's "finite but unbounded" continuous spacetime manifold continuous (via string energy) to higher dimensions. (It would be infinitely continuous, but for my result that the 4 dimension horizon is identical to the 10 dimension limit, which implies measurability.)
Tom
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Jason Wolfe wrote on Aug. 2, 2010 @ 04:25 GMT
John,
You do raise an interesting point. In the first few microseconds of the Big Bang, why didn't the universe just become a Black Hole?
The W and Z particles of the weak force are a hundred times more massive than the neutron that emits it. Of course, the W particle doesn't last very long, about 10^-25 seconds. This puts energy conservation on shaky grounds. In contrast, I guess the Big Bang is thought to occur when a singularity pops into existence, once in a ridiculously long time.
Events like these really do undermine conservation of energy.
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Lawrence B. Crowell wrote on Aug. 2, 2010 @ 15:50 GMT
One point of using sphere packing to look at these problems is these structures are quantum error correction codes. The set of transformations are modular, or given by modular functions. This means quantum gravity might modular, quantum information is conserved by the n-folding of modular functions. For the E_8 group and the higher Leech lattice system, which has a triality on 3 copies of E_8, the underlying functions are Jacobi θ-functions of the form. These functions are solutions of the heat equation, or constitute the heat kernel. These functions exist on the (z,t) space and for t - -> it are of the form
Θ(z, t) = 1 + 2sum_{n=1}^∞ e^{-πin^2t}cos(2πnz)
which solve the equation
∂θ/∂t = (1/4πi)∂^2θ/∂z^2.
This is the heat equation for t, where ∂^2θ/∂z^2 forms the Laplacian of the heat kernel. For t - -> it is a form of the Schrodinger equation. So there is an underlying unitarity to the modular system. This is a unitarity on the string world sheet of two dimensions z parameterized by t, which is in complex variables the Riemann sphere. The parameterization of string world sheets is a cylinder, and if we include two caps to close the end, each cap is contractible to a point. The string world sheet is stereographically mapped to the Riemann sphere, and this is a parameterization of Riemann sheets.
If this is returned to a heat equation form, the Laplacian on the complex plane, with z = (z1,z2) has the form
Δ = ∂^2/∂z^2 = ∂^2/∂z1^2 - ∂^2/∂z2^2
and the time variable plays the role of a conformal factor which maps the two dimensional Riemannian space (Riemann sphere) from one to another with a different radius. So this is a Ricci flow on the string world sheet. The Laplacian describes string dynamics with the Lagrangian
L = ½ sum_k(∂X/∂z_k)(∂X/∂z_k) + . . .
and the Ricci flow determines the domain of the scale length for the string. This parameter then extends from the Planck length, the cut off, to the horizon length, or sqrt(horizon area). That horizon could be the horizon of a black hole the string is interacting with or the entire spacetime cosmology. So these are the UV and IR cutoffs in the scaling of the system, which are the “caps” mentioned above. These caps are balls, in the space of possible string world sheets they are 3-balls, with 2-sphere boundaries. These spheres then contain information about scaling bounds.
Cheers LC
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John Merryman replied on Aug. 3, 2010 @ 00:01 GMT
Lawrence,
With all the extra dimensions and complex math, wouldn't it be far easier to diagram a process by which what is falling into black holes emerges as quantum fluctuation across space? This would be a far simpler explanation for redshift and cosmic background radiation, that that Big Bang/Inflation monstrosity.
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Lawrence B. Crowell replied on Aug. 3, 2010 @ 01:31 GMT
L. Susskind has done these
cosmology lectures, and I can only suggest you watch these. Big bang and inflationary cosmology is pretty well established. The basic big bang cosmology is benchmarked by a range of observations. Inflation does not explain everything at this point, It does solve a range of problems, in particular inflation solves the flatness problem. Aspects of that prediction have been born out with the WMAP data on CMB anisotropy. Inflation is an approximatio to something else, for it has to be narrowly constrained to within 63 e-folds and the nature of the scalar field has to be "crafted," and so forth. It is a bit like the same situation with the standard EW model in particle physics.
Cheers LC
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John Merryman replied on Aug. 3, 2010 @ 02:22 GMT
Lawrence,
I'm sure block time and many worlds are equally well established.
One of those range of observations they missed by a mile was the rate of expansion(minor point), so now we are supposed to accept dark energy.
Inflation was a prior fudge factor. That's why it has to be constrained, "crafted," and so forth. Why did it bother to slow down to the rate of expansion which presumably exists now? There surely isn't enough gravitational drag to do it, especially in light of all the "dark energy" presumably still pushing things apart.
While the effect assigned to dark energy was completely out of the blue for Big Bang theory, it apparently is a close match for the Cosmological Constant, which Einstein originally inserted to balance the effect of gravity and maintain a stable universe. So what prevents any discussion of the remote possibility that that is exactly what it does?
Inflation might solve the flatness problem, but at the expense of creating far more problems. For most people, the obvious solution is to go back to the start and figure out what is the underlaying problem, but obviously cosmologists are much smarter than other people, so they could never be wrong in the first place and this would just be a waste of time.
The cosmological background radiation is extremely smooth and since the universe began with an enormous explosion, it must have been some initial shock wave which caused this smoothness. What if it's just vacuum fluctuation and there is a transition level above which it isn't stable and collapses back into the vacuum? Essentially the vacuum expands and collapses. On top of explaining the redshift and CMBR, it also explains gravity.
Oh. no! I just don't understand. I'm to uneducated in the finer points of cosmology. Fact is Lawrence, you don't understand dark energy, or Inflation either, because no one else does. They are fudge factors that no one has effectively constrained or "crafted."
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T H Ray replied on Aug. 3, 2010 @ 12:37 GMT
Lawrence,
Excellent explanation of Planck scale string ontology. Moreover, because we know that the n-dimension manifold is compact (generalized Poincare Conjecture), I conjecture that an n-dimensional Euclidean sphere kissing model should lead to a string theory measurement, by thought experiment even if the technology is far into the future.
Tom
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Steve Dufourny replied on Aug. 3, 2010 @ 20:11 GMT
hum hum interesting I see spheres, hum hum interesting.
Insert thermo and meca ....rotations, proportionals.....in 3D without strings and external cause of mass please.
You loose your time,I say that humbly and sincerely ,you repeat always the same, don't be offensed but really it's bizare.
It's as if you had a job from some universities or business teams, what are these extrapolations without real physicality.It's not possible all that...
I don't understand why these extrapolations.
If I had proofs,ok I will admit but there it's ironic.
Don't teach that to people please, it's all false.
Not your intrinsic methods, but the generality of your referential is puerely false.
Bizare all that.
For the tittle, of course the philosophy is the sister of the truth and the developpement of the evolution,like a quiet music of building.
PLANCK SCALE ....ULTIM MAIN CENTRAL SPHERE.....I have a big paradox in my Planck scale really, and I am serious.The smallest is also the biggest volume of the fractal.....hope you understand what I say.
The number of the entanglement is specific, and the volume of the main central sphere is the most important in my line of reasoning....thus what is really the Planck scale.....Furthermore the lattices between spheres are correlated also.....and the evolution of lattices, also thus where are the essentials....
Regards
Steve
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Lawrence B. Crowell wrote on Aug. 3, 2010 @ 14:35 GMT
This approach with Jacobi θ-functions segues into sphere packing. The symmetries of the θ-functions derive a finite element subset of the Heisenberg group. The Hesenberg group emerges from the stabilizer of lightlike geodesics in E^n (Einstein spacetime). The construction of light cones is then possible from the identification with poles on S^n. The null condition on light rays is defined by a projective geometry or equivalently by a stabilizer of O(2,n) (elements g such that gx = x) that is
R\times SL(2,R) x O(n-2)|X Heis(2n-3) ( |X = semidirect product)
where Heis(2n-3) is the Heisenberg group of 2n – 3 dimensions. In AdS_{n+1} with two timelike directions the projective geometry is then “mod 2-planes = P,” just as regular projective space is R^n/(x ~ λx) and the lightcones or null directions are defined by O(2,n)/P. Now if we include the positive and negative sequences on S^n, this is related to the space PT^+ and PT^- in twistor theory.
The discrete structure of E_8 and the Leech lattice Λ_{24} have Jacobi θ-function realizations, which are discussed at length in Conway & Sloane. The Jacobi θ-functions also obey a heat equation, and the heat kernel is a Fredholm alternative. This then should lead to a gauge-theoretic like system for gravity within a geometric quantization.
Cheers LC
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Don Limuti (www.zenophysics.com) wrote on Aug. 4, 2010 @ 02:50 GMT
John M. I like your concept: "Essentially the vacuum expands and collapses. On top of explaining the redshift and CMBR, it also explains gravity."
Lawrence C. likes to quote from the math Bible, which has many adherents. I personally like math (and Lawrence) but always keep in mind a mathematician's allegiance is to logic that follows from axioms. This may or may not correspond to physical reality but in either case the logic is perfect.
Dvali and Gomez's ideas about the Planck Length have merit. They should also show that the Planck Mass is the limiting mass at the Planck Length.
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Steve Dufourny wrote on Aug. 4, 2010 @ 11:26 GMT
Dear Don ,interesting could you develop please,why that explains gravity???
Essentially the vacuum expands and collapses. On top of explaining the redshift and CMBR, it also explains gravity."
For the maths.....I think it's a problem of cocktals of consfusions.
That implies problems about our foundamentals.Because the main parameter of these researchs is totally different than a ^pure rational universality.
People even when it's false continues for jobs, I can understand,indeed we all need to eat.But that becomes so ironic, that I am going to begin to analyze in details these stupidities.We can't teach that at universities.It's not possible.Our laws are our laws.
We can't play and laugh with our physicality, objective and realistic.
The pub and the business never must cause problems about our inetrnational language and its series of equations.
I am here to develop my theory,not for being in an ocean of business.
Regards
Steve
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Tissa Perera wrote on Aug. 4, 2010 @ 12:51 GMT
Can a black hole explode?
Is not the singularity within the black hole far less than
Plank length?
/Tissa
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Lawrence B. Crowell replied on Aug. 4, 2010 @ 12:55 GMT
A black hole quantum mechanically radiates in a thermal or blackbody spectra. As it radiates mass away the temperature increases which in turn means it radiates mass-energy out faster. Consequently towards the end ot this process the black hole does violently emit radiation in what might be called an explosion.
Cheers LC
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Steve Dufourny replied on Aug. 4, 2010 @ 16:36 GMT
Hi dear Tessa, Of course never,it's not possible.Because all Spheres(here the BH or the B body if you prefer)have a pure rule of complementarity, theses super mass have a rule, they aren't dedicated to explode,that has no sense.
The equilibrium is logic between mass.They help for the building, all rotates around a center and these spherical BH turn around a center also.....thus why an explosion, we can't confound a star and a BH ...ALL HAS A RULE.
Best Regards
Steve
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Don Limuti (www.zenophysics.com) wrote on Aug. 4, 2010 @ 20:56 GMT
Steve,
I was just quoting John Merryman. He was going back and froth with Lawrence about cosmological inflation. I think John has an interesting model that builds on gravity (it does not explain it) and it helps explain inflation.
The phrase "the vacuum expands and collapses" brought to mind the sheet of rubber that is used to "give a feel" to how general relativity works. The curvature of space-time is represented by the dimples that masses make in the sheet of stretched rubber. The gravity the mass produces is the curvature it causes in the rubber. I think of this rubber universe as being on top of a circular drum.
If the circumference of this drum were to expand stretching all the rubber at once we have something that looks like inflation. The universe is bigger and yet all the masses are in their same relative places on the rubber sheet. A neat visualization of inflation.
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John Merryman replied on Aug. 5, 2010 @ 03:11 GMT
Don,
interesting point about the rubber sheet analogy: Within those gravitational dimples, space is falling inward, but from what? Does the rubber sheet represent flat space? Could it be the sheet is expanding outward between the gravity wells? Such that the two elements balance. This would be far more relativistically coherent. The concept of flat,Euclidian space is that expansion and contraction are balanced. So the "hills" balance out the wells.
My argument is the expansion of space is elemental to space, ie.a form of positive quantum fluctuation. This would explain why it appear, under rigorous scientific examination, to equate with a cosmological constant, not a Big Bang singularity.
This then is only stable up to the level of 3.7k, which explains the smoothness of background radiation,without resorting to Inflation.
It then collapses in causal chain reactions, creating the stringy plasma of interstellar and intergalactic connections, as well as the spatial collapse of gravity.
Not that the pros are buying it,but then epi-cycles lasted for fifteen hundred years, as everyone knew the earth was the center of the universe, just as everyone now knows the only possible explanation for redshift is recessional velocity.
my replies to this discussion will be limited for a week, as I'm writing this on a borrowed iPad,in a hotel room in Lexington Ky., in the bathroom, after everyone else has gone to bed.
Pony Finals and the daughter is the boss at the moment.
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Steve Dufourny replied on Aug. 6, 2010 @ 19:53 GMT
Thank you dear Don for this beautiful explanation.It's interesting this kind of explaination.
Inflation is correlated in my humble opinion to evolution.
I would insist on the spherical system of our Universe.It's logic it's the base of my Theory, an Universal Sphere and its cosmological spheres and its intrinsic quantum spheres......they build these sall spheres....
It is indeed very important, even essential to identify all these spheres and their rotations.The rotation is a proportionality for the mass.
The masses are became more complexs in proportion to their densities and volumes.
Rotations and the inflations are correlated of course.
The universe can't be flat, and therefore it spherize itself, it carries its dynamic into a specific harmonic series.
If this sheet of rubber, with a center spherize, itself is taken in first consideration.It is easy to identify an evolution of rotations and centres.
These spheres undergo specific dynamics and coded, according to an universal oscillation.
At a specific volume and density , this Universal sphere will be towards the perfect equilibrium between mass.
We see our past dear Don we see our past, and we shall see better with these rotating spheres.....the topology is essential for all improvements of our technology.We turn and it's essential.The sphere evolves and complexificates itself.If we don't insert the rotations around a center inside a sphere, never we shall understand where we are .......
Best Regards
Steve
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Don Limuti (www.zenophysics.com) wrote on Aug. 5, 2010 @ 07:52 GMT
John,
I like it! I will get carried away and make a physical model of it.
1. Start with the rubber sheet stretched over the drum.
2. Only this time the drum is full of water and the rubber is floating on the rubber.
3. The circumference of the drum where the rubber attaches can float up and down.
4. When a mass is placed on the rubber sheet it dimples downward and displaces some water.
5. This displaced water pushes the rest of the water in the drum upward. Just like pushing a beach-ball into a bathtub.
6. The average level of the water in the tub stays the same. And the average level of the rubber sheet stays the same.
7. The analogy being that the average curvature of the universe is flat no matter how much or little mass there is in it.
Does that fit with you model?
Good luck with the Pony.
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John Merryman replied on Aug. 5, 2010 @ 12:22 GMT
Don,
Exactly!
I first started to question physics after learning expansion and gravitational contraction are balanced. it seemed for more likely to be a complementary relationship,than the coincidence Big Bang proposes. Modern cosmology really does seem to be a convoluted mess of complex theories, tied together with some rather outrageous fudge factors. It really does seem to be a modern form of epicycles, with some very basic misunderstanding leading to increasingly wild speculations, but those in the field view every Escher Scetch of a mathematical theory as more real than any logical observation. The assumption physics is Counterintuitive has been perverted to mean it is illogical.
Not a big fan of iPad, but it is useful. Thanks for the consideration.....
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T H Ray replied on Aug. 5, 2010 @ 13:09 GMT
"Counterintuitive" means that the logic of naive realism is violated.
Tom
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John Merryman replied on Aug. 6, 2010 @ 00:19 GMT
Tom,
I'm not sure I see your point. There are lots of things which are counterintuitive,but not illogical. The issue of whether the sun moves across the sky, versus the earth rotating would be a significant historical and scientific example. My point is that physics is going to extremes with this.
The idea of block time would be a good example of a mathematical model predicting a fallacy. As a four dimensional geometry can be devised, using the sequence and duration of events as an additional dimension to three coordinates of space, many physicists will argue with all conviction that this dimension of time is physically real and the point of the present is as subjective as any point in space.
Well, the old naive saying that you can't have your cake and eat it too is a more accurate physical description than block time.
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T H Ray replied on Aug. 6, 2010 @ 10:18 GMT
John,
You cling to this false opinion that physicists think time is physically real, though you have been informed repeatedly that only _space_time is physically real in general relativity. How do you expect to draw valid conclusions from false premises?
Tom
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John Merryman replied on Aug. 6, 2010 @ 11:21 GMT
Tom,
That would involve an entire discussion of just what physics considers "physically real."
Spacetime puts space and time on an equal footing. I don't agree. one's position in time is not as relative as one's position in space, because there is only what is present. Time is an emergent effect of this present activity. It is space, as I've argued previously, that is the foundational vacuum. I can't repeat the entire argument, because of time constraints. Unfortunately, you don't seem to have enough respect for my position to remember it.
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T H Ray replied on Aug. 6, 2010 @ 11:47 GMT
John, known physics isn't about having a "position." It's about understanding why we know the physics to be true, and how we know it.
General relativity is a quite mature theroy.
Tom
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John Merryman replied on Aug. 6, 2010 @ 14:11 GMT
Tom,
Correlation and equivalence are not the same thing. Time and distance can be correlated using the speed of light, but that doesn't make them equivalent. Just as we can use ideal gas laws to correlate temperature and volume, but that does not make them equivalent.
Mature and immortal are not equivalent either.
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T H Ray replied on Aug. 6, 2010 @ 16:21 GMT
Ah, John. As always, I just can't understand where you get this stuff, though I know it isn't from a text on general relativity. Time and distance are neither "correlated" nor "equivalent" in Einstein's theory.
Time is simply an added coordinate in a geometrical coordinate system, making it continuous with space. Because time is continuous with space, the entire _spacetime_ structure admits no physical independence of either space or time. A distance measure can be converted to a temporal measure, because there exists a constant unit, c, that permits rigid geometrical transformations at relativistic speeds and distances. It's all geometry, as I have tried to explain over and over. A four dimension Pythagorean Theorem.
And BTW, temperature and volume are _not_ correlated. They are proportional. The difference is important. A correlation is a statistical relation between variables, where we may lack a theory. We do know the cause of changes in temperature proportional to volume, by the kinetic theory of matter.
Tom
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Lawrence B. Crowell wrote on Aug. 6, 2010 @ 17:08 GMT
Tom,
To be fair it might be said that proper time is fundamentally real in relativity. So we might think of the classical mechanical universe as consisting of world lines with their own proper times. Such a world is utterly without any unity, until we include null rays with zero proper time. This provides a way to transform between these various frames with their unique proper times. This is what constructs the “field” called spacetime which permits a transformation between local frames.
Cheers LC
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T H Ray replied on Aug. 6, 2010 @ 17:22 GMT
Of course. It's still a geometric transform, however. That the boundary is zero gives us a fixed point. I can't see at all how this relates to John's rhetoric about "correlation" and "equivalence" between time and distance. The time coordinate is still a simple parameter of reversible trajectory in classical mechanics. Continuous function geometry.
Tom
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Lawrence B. Crowell wrote on Aug. 6, 2010 @ 22:47 GMT
Tom,
Sure, much of what John is referring to is "mysterious." :-) I think John is referring to some popularizations which can end up makiing statements about time eqivalent to space. I think this refers to how the speed of light is a conversion factor between spatial coordinate distance and time.
Cheers LC
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John Merryman replied on Aug. 7, 2010 @ 02:45 GMT
Lawrence,, Tom,
I realize it's geometry, but that makes it a modeling device for defining reality, not a fundamental proerty of it.
Why is it that time is described as one dimension? One dimension of space is a line. Two is area and three is volume. This all seems a rather reductionistic description and modeling is reductionism. it is very useful, but it is also necessary to understand the limits,or it becomes counterproductive, because it distorts further understanding.
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T H Ray replied on Aug. 7, 2010 @ 11:40 GMT
Time _isn't_ "described as one dimension" in general relativity, John. Time is continuous with the geometry of space, as an additional coordinate in a spacetime metric. You cannot seem to grasp that time is an illusion in the classical theory -- that it is a record-keeping device, a way for an observer to correctly determine her position and velocity in spacetime by accounting for the effects of motion relative to other observers.
The proper time limit allows access to boundary conditions that inform us that the universe had a beginning in classical theory. Sure, there may "really" be no such boundary, but that's what quantum gravity is out to explain -- how do nonlocality and uncertainty join with classical mechanics?
It is not contemporary physical theory that limits understanding. One limits one's understanding by starting with false premises.
Tom
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John Merryan replied on Aug. 7, 2010 @ 12:43 GMT
Tom,
The only "fixed point" in time is the present. The projection of past and future are "record keeping devices." Time is not an "illusion." It is an effect of the changing configuration of that which is present. Beginnings and endings are a function of the effect of information of this changing configuration, because the end of one configuration is due to losing it's constituent energy and this energy goes on to other configurations. The process of time goes from past units of configuration to future ones. These units of configuration go from being in the future to being in the past. Beginning and end only apply to the units, not the process. even with Big Bang theory, they now put in the context of multiple universes. So even in this theoretical model, the universe becomes a unit in a larger process.
Looks like I'm stuck here for the entire show, till a week from tomorrow. That means I will always be present, but these days will go from being in the future to eventually being in the past.
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T H Ray replied on Aug. 7, 2010 @ 13:31 GMT
John, you are correct that the fixed point of time is the present. That is, any point of spacetime that one arbitrarily chooses is where the Big Bang began.
What you don't understand is that one needs four dimensional spacetime geometry to make this conclusion stick. Your naive view of past, present and future assumes a linear temporal progression of events in an absolute background space. That isn't the way the universe evolves.
If you want to talk about configuration space, and events changing with energy as you describe -- then go study quantum coherence and decoherence. Be prepared, however, to give up your notion of time, because it doesn't exist in that domain.
I really have tried to unravel your thinking, and it seems to me that you are trying to force a classical time trajectory on quantum events. If it were that easy, we would already have a bulletproof theory of quantum gravity.
Tom
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John Merryman replied on Aug. 7, 2010 @ 14:23 GMT
Tom,
I certainly not arguing time is a single linear dimension. To repeat, it Is the changing configuration of what is. Therefore every potential clock is it's own measure of time. As reLativity shows, these measures are varied from one clock/frame to another. Maybe you understand this, but as Lawrence pointed out, this idea of time as a " fourth dimension" causes a great deal of confusion and misinterpretation among those who don't seem to grasp it is a geometric model of the relationship between distance and time, but think there is some fundamental metadimension of time. It it this interpretation I have problems with. If you don't think it is a prevalent notion, go back and read some of the essays and discussions in the Nature of Time contest.
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T H Ray replied on Aug. 7, 2010 @ 15:28 GMT
John Merryman replied on Aug. 7, 2010 @ 16:42 GMT
Tom,
In the context of the discussions on this board, the most obvious example would be time traveling wormholes.
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John Merryman replied on Aug. 8, 2010 @ 02:04 GMT
Tom,
Taking a reductionistic geometric model, like describing time as a dimension and building a theory of reality up from it, such as proposing one could travel around this dimension of time as though it is space, would be like taking the Escher drawing of the waterfall and developing an entire field devoted to figuring out how to make a perpetual motion machine out of it. Some things that can be modeled in theory, cannot exist in reality.
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T H Ray replied on Aug. 9, 2010 @ 12:02 GMT
You've got it exactly backwards, John. Geometry is holistic, not reductionistic.
It is because of quantization -- the reductionist paradigm -- that we deem perpetual motion impossible. In a geometric (continuous functions) theory, the universe itself is a pertual motion machine.
Tom
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John Merryman replied on Aug. 9, 2010 @ 20:23 GMT
Tom,
I just made the point that the concepts of beginning and end are an effect of temporal units and the energy is always going onto the next, so I realize the universe is open and just transferring energy around.
The point I was making, which you ignored or did not get, was that such concepts as time travel through wormholes in space, based on the geometric correlation of time and distance, called spacetime, is like postulating perpetual motion based on the two dimensional illusion of Escher's waterfall. You can't just bend time around and go back in history because gravity bends light and physics conflates distance and time.
To repeat, just because something works according to the factors the discipline selects, doesn't mean it will work when all other factors are included.
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T H Ray replied on Aug. 9, 2010 @ 21:05 GMT
If the universe is "just moving energy around," it's closed, not open. Dynamics guarantee recurrence.
I know what wormholes are, John. I ignored it because I didn't want to commit to yet another exchange about the role of time in general relativity. Wormholes are classical -- and if you haven't got that from me by now, I don;t think I can make it any clearer.
Tom
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John Merryman replied on Aug. 10, 2010 @ 01:19 GMT
Tom,
Would infinite qualify as closed?
You asked me what a "metadimension" is and I said that wormholes are the best example being discussed in these blogs.
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T H Ray replied on Aug. 10, 2010 @ 10:22 GMT
John,
The Einstein universe is finite but unbounded. When one speaks of particles separated by infinite distance, such as entangled photons, it is in reference to the boundary (zero) of an expanding universe. When you speak of "moving energy around" dynamically, it begs a closed universe.
Again, because wormholes are classical (solutions to general relativity equations in 3 + 1 dimensions) I can't find any meaning to "metadimension" in that context.
Tom
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Eckard Blumschein replied on Aug. 10, 2010 @ 20:52 GMT
Are circle, area and volume of a sphere finite but unbounded? Their measures are given by integration extending from a chosen point to the bound of exhaustion.
In contrast to one out of many worlds, the universe is thought to include anything without any known bounds. It would be reasonable to consider it inexhaustible if this did not collide with the religious belief shared by Einstein and with the hypothesis of a big bang creating the whole universe.
Why did the Schwartzschild solution suggest an eventually circular and therefore finite time scale with strange singularities where jumps between minus and plus infinity occur? To my best knowledge this, white holes, and the Rosen bridge between world and antiworld are pure mathematically based speculations. I might be wrong but I put them into my drawer of possibly wrong distracting curiosities together with nice medieval perpetua mobila, Cantor's aleph_2 and Jason's UFOs.
I live in what Zeh called our world, and I hope for being able to convey the insight that the world of what already happened is fundamentally different from the expected one. This insight is missing in theories that admit time travel.
Eckard
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Don Limuti (www.zenophysics.com) wrote on Aug. 9, 2010 @ 22:37 GMT
John,
I continue to like this conversation thanks to you Tom and Lawrence. Let me nit pick the statement: "The only "fixed point" in time is the present". This could mean a lot of things, but I believe that it is intended to convey the thought that at we can have a pure space without time in the present moment. I believe that this is the conviction of many but that it is flawed because space and time in physics always go together. Here is my model:
I have a camera that has a shutter speed duration that is 100 times shorter than any light wavelength that enters the camera. When I take a picture of a garden landscape the image is "black". There is no landscape to see at the present moment and it follows that there is no space at the present monent. In my opinion at the present moment neither space or time exists.
Once we allow reasonable shutter times we start getting reasonable pictures and a world view that has space and time linked. Does the world of physics have reasonable shutter times?
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T H Ray replied on Aug. 9, 2010 @ 22:58 GMT
Don,
We do have " ... pure space without time in the present moment ..." but there's no matter in it. The particles of a quantum non-relativistic universe are entangled to infinity, though.
The reasonable shutter time in physics is called Planck's Constant.
Tom
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Georgina Parry replied on Aug. 9, 2010 @ 23:06 GMT
Don,
is it that it does not exist or only that it can not be observed with a very short shutter time, that does not allow information to be transferred and interpreted? It has to be observed to be experienced, so the experience does not exist, I agree. There is no subjective reality that can be formed from such a short interval.
However there must be a reality that exists that can allow the information to be generated. So that it can be received and interpreted after a longer interval. Can there be unseen reality that is real. Yes. I accept that there is a real rabbit in the magician's hat prior to its extraction. Even if the rabbit climbed in itself and no one say it do so. I accept that the elephant behind the mirror, that no one can see, is still a real material entity. It is not necessary to see it to accept that it is real. Observed reality can not spring fully formed from nothing but time,imo. I do not believe in magic.
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John Merryman replied on Aug. 10, 2010 @ 02:21 GMT
Don,
I agree that a dimensionless point of time would be a complete absence of motion or information, but my arguemnt is that the very concept of time is an effect of motion, much like temperature is an effect of motion. Now if you completely froze motion, like zero shutter speed, nothing would effectively exist. It would be a temperature of absolute zero.
Now ask yourself; How...
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Don,
I agree that a dimensionless point of time would be a complete absence of motion or information, but my arguemnt is that the very concept of time is an effect of motion, much like temperature is an effect of motion. Now if you completely froze motion, like zero shutter speed, nothing would effectively exist. It would be a temperature of absolute zero.
Now ask yourself; How does that picture form? Is it because there is a dimension of time, of which the camera cuts a slice? Or is is completely a function of motion, in which the shutter of the camera is physically open and the physical motion of light enters it, creating an impression? What happens in the second description is not that the camera moves along a fourth dimension from the opening of its shutter, to the close, but that the action of its opening occurs, recedes into the past and is replaced by the event of its closing. There is no fourth dimension. It is just that for as long as we are alive, we are part of these events, so we are going from one to the next, but eventually we die and our lives are one more unit of time that was first potential, then actual, then residual.
What the camera is doing is recording information carried by the light crossing its lense.It is taking a slice out of a continuous process and if you make that slice so thin it can't collect information, there is no picture, but the energy would have just bounced off the lense.
The problem is that our rational, left side of the brain is essentially a clock, in that it is recording series of events and trying to make sense of them. So we think of it as going along a narrative sequence, thus Newton's absolute flow of time. Remember he lived at a time when Christian monotheism was still overwhelmingly powerful and the effort to create a united civilization, based on the shared narrative of the Bible, wasn't open to question, since it was so fundamental to the very thought process, even though the idea of a benevolent God had become tattered. By the time Einstein came along, the problem of incorporating this eternal flow into a logical understanding of physical reality was becoming difficult and he proposed a very innovative method of combining it into spatial geometry. While this solved some problems, it caused others, such as the idea that this dimension of time could be curved around and if one were to find a shortcut through those curves, one could time travel.
The point I keep making is that we are looking at time backwards. It is not that the point of the present moves along this dimension from past to future, but that the changing configuration of what is creates and replaces these events, such that it is they that go from being in the future to being in the past. The earth does not travel the fourth dimension from yesterday to tomorrow. Tomorrow becomes yesterday because the earth rotates.
In this view, every motion is effectively its own clock, so there is no universal flow and if some outside effect, such as gravity or acceleration, were to cause the clock to speed up, that wouldn't be because of a distortion in the spacetime geometry, but simply because that clock's internal motion was affected by outside effects. The twins didn't travel along different timelines because of spacetime geometry. One just happened to be in circumstances which caused its atomic and molecular activity to speed up.
Think of it in terms the difference between a geocentric and heliocentric view of the solar system. For most of human evolution, we saw the sun as moving across the sky and it seemed quite obvious, but then people started trying to make sense of the heavans and the models they made, based on ideas they understood, such as wheels and gears, became ever more complicated, but few people thought to question that apparently basic assumption that they all must be moving around in the heavens. The idea we might be just one more object moving about seemed ridiculous. Eventually we realized it wasn't that the sun was moving east to west, but we were rotating west to east.
Now consider that in terms of time. Throughout history we have seen time as flowing from one moment to the next and what happens in the future is more cause for concern that that which already happened, since it might kill us, so we are fundamentally trained to see it going in one direction. In fact the very concept of history is the collection of these narratives and an effort to descern a larger pattern. So it isn't that easy to see our postion as extant being special, but it is the extant which is the physical reality. Thus it is the events which are going the other way, much as it's the earth that moves, not the sun.
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Don Limuti (www.zenophysics.com) wrote on Aug. 10, 2010 @ 23:55 GMT
I appreciate the responses,
Ray, Thanks, of course, the Planck scale! This is what this blog is about. I am suspicious of space without matter and think they rely on each other for existence.
Georgina, Yes, I believe there was a rabbit in the hat before the extraction, but is there a rabbit in the hat right now? I do believe in an "out there in the real world" that consists of space and matter. However I also believe, the matter always brings along a clock.
John, You say time is an effect of motion, I agree with that as far as it goes. But I would go on to say that motion is an integral and continuous part of the world, and therefore we are stuck with time. Of course we can try to hide this nasty thing "time" by limiting our vocabulary to just the terms "distance" and "velocity", kinda like hiding an elephant behind a tree. You go on to say that "every motion is effectively its own clock, so there is no universal flow" This does not make much sense to me. I interpret it as saying something like "If every human carries a clock then time is useless".
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Lawrence B. Crowell replied on Aug. 11, 2010 @ 01:51 GMT
Don,
Even a particle at rest can be thought of as moving at speed c along the direction x_0 = ct. If you observe another particle moving in space with a velocity v there is then a transformation principle --- Lorentz boosts. The result is that time is a local property, or the invariant is proper time, and the proper time for all world lines or geodesics are connected by the symmetries of spacetime.
Cheers LC
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Georgina Parry replied on Aug. 11, 2010 @ 01:59 GMT
Don,
thank you. Re your question, you should ask the rabbit. It knows whether it is in the hat or not. It does not need an outside observer to tell it where it is or when, it just is - really is, somewhere. I don't know if the rabbit has a clock with him though.. I am now picturing the white rabbit from Alice in wonderland!
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John Merryman replied on Aug. 11, 2010 @ 02:43 GMT
Don,
I didn't say time doesn't exist. I'm saying it is an emergent effect of motion, rather than a dimensional basis for it. It is more like temperature, than space. As I see it, the absolute would be the vacuum/space. From its apparent instability arises fluctuation. Time and temperature are effects of this fluctuation. One being the changing configuration and the other being the degree of activity.
It is safe to say that human beings are many orders of emergence beyond that of time and temperature, so if you were to consider them to be illusions based on their being an effect of motion and not the basis for it, what does that make us?
I think that while the rational, linear, left side of the brain is a form of clock, the emotional, non-linear, right side of the brain is a form of thermometer, in that it registers the multitude of energies and influences that we cannot rationally process.
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Don Limuti (www.zenophysics.com) wrote on Aug. 11, 2010 @ 08:07 GMT
Hi all,
Lawrence, I suspect that there is no such thing as a particle at rest. This is a minority position I have taken.
Georgina, My favorite rabbit is Elmer Fudd's nemesis Bugs Bunny. "Where is that pesky rabbit?"
John, I too feel that motion or how particles move is the key to time space and physics. Just because children are an emergent phenomena of their parents I do not call them illusions (at least not all the time).
I just read a most interesting book "Human" by Gazzaniga (left brain/right brain originator) in which the current work of Jeff Hawkin's is outlined. Recommended.
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Lawrence B. Crowell wrote on Aug. 11, 2010 @ 12:58 GMT
Don,
This depends upon what you mean by being at rest. A particle with a significant Compton wavelength λ = ħ/mc (or small mass) interacts with the vacuum so that if one were to perform a sequence of measurements in a Zeno type of process it would be measured to exhibit a Langevin or Brownian type of motion.
Cheers LC
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John Merryman replied on Aug. 12, 2010 @ 21:17 GMT
Don,
That's " waskally wabbit."
It's not simply how they move, but that there is motion to the degree any form of contrast is created, such that one configuration becomes another. Yes, there can be any number of further emergent effects, such as entropy, or even our conscious perception of this process, but change is time.
E. O. Wilson described the insect mind as a thermostat, but it's been shown that ants can count their steps and that's a form of clock/sequence.
Kids start as parents dreams and parents end as kids memories, so maybe we are all illusions.
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Georgina Parry replied on Aug. 12, 2010 @ 22:08 GMT
John,
very poetic- but dreams and memories also require biochemistry. The parent has an ever changing biochemical structure as does the created child. That is the underlying objective material reality separate from experience. There are Continual, ongoing physical /chemical processes (that involve spatial change of position of matter and/or sub atomic particles) whereby all that happens occurs and all that is experienced is generated.
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John Merryman replied on Aug. 13, 2010 @ 02:48 GMT
Georgina,
Trying to peel apart all the levels of emergence is a Sisyphean task, given the degree to which they are bound together. Then again, the desire to take on such tasks is one more layer of the process.
Don't loose sight of the forest for the trees and don't loose sight of the trees for the forest.
If you peel away the poetry, though, the next step is a long way down.
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Georgina Parry replied on Aug. 13, 2010 @ 04:01 GMT
John,
Its OK to peel it back and take a little peek below. That is not throwing out the experience, the emotional connections, the feeling, as unimportant. What matters to us most as human beings is all of the experience of being human.
Having said that.. One can't have the forest without the trees. One can have trees with out a forest. For example emotion is important to us but there is no emotion (or little) without adequate levels of the neurotransmitters or hormones by which the emotional experience is generated. The emotion can not exist separate from the biochemistry. However the isolated neurotransmitter and hormone chemicals can exist just as chemicals.
One layer of reality exists independently of the other. It does not require human experience to exist. Is generally unobserved and must exist so that the next layer, experience, can be generated. That next layer, experience, can -only- exist because of the underlying layer.
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John Merryman replied on Aug. 13, 2010 @ 13:57 GMT
Georgina,
I fully agree the primary stages must pre-exist the emergent stages, much as the first floor of a building must come before those built on it. the problem is that when those emergent levels exist, they affect the context of the prior levels, such as if you were to build more floors on a building then the lower levels can support. Also trees out in the open are different from those in forests. They grow out, more than up.
So, from our perspective, we cannot effectively consider the foundations in isolation. For one thing, we tend not to have a clear understanding of them and formulate theories subconsciously incorporating different layers, such as modeling time as a dimension, rather than a process. Since we view it through the lens of our complex existence, we have to understand the lens in order to see through it and realize much of our ability to think and understand is a function of the lens, so that there might not be a foundation which is comprehensible to our current ways of thinking.
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John Merryman replied on Aug. 15, 2010 @ 03:43 GMT
Georgina,
It's all connected.
Bottom up and top down.
Chaos and order.
Energy and information.
Future and past.
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Jelle U. Hielkema replied on Aug. 15, 2010 @ 13:36 GMT
All,
I'm coming from 'the other side', i.e. Philosophy vs Physics but every now and the have a peek here. If this, a website which I developed as a sequel to my book
http://www.amazon.com/Natural-Theory-Dealism-Understandi
ng-Humanity/dp/1434906752
together with an australian friendcan be of any help in your discussion, please have a look at http://www.rainbow21122012.org/
The movie at the beginning, apart from being 'emotionally beautiful' tells a lot about how Nature works and the various articles, especially thos behind the 'church windows' dress it up from a current and future society perspective.
Jelle
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