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#2460 by ThatOtherGuy on 26 Oct, 2017 12:58
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Quantum Weirdness of Light Was Just Confirmed by Shooting Photons Into Space
Ok, this is (most probably) off-topic, yet, I think it's worth a mention here
I'm referring to this experiment about the so-called "Wheeler's delayed-choice" (details here)
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#2461 by Rodal on 26 Oct, 2017 13:08
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When discussing "vacuum" we have to clearly define and agree on what one means by "vacuum".
In the link above, it says that the Ozsváth and Schücking Metric is a parallel plane wave (pp-wave) solution. This is considered anti-Machian?
That seems strange to me, since pp-waves are known to be approximations of waves generated by a source, at distances much greater than a wavelength. We have recently seen what it takes to create gravitational waves.
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Also, the EM ZPF is a source-free solution of the EM field. I would interpret this Ozsváth and Schücking Metric as an analog to a source free gravitational field. It's not isomorphic to Minkowski space-time because it's wavy, but it has to be there as the ground state of the field.
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Maybe I'm missing something, but this doesn't seem very anti-Machian to me, IMO.
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The discussions of metric "vacuum solutions" within General Relativity deal with solutions for which there is constant zero density (*). This is the vacuum of General Relativity, not the Quantum Vacuum (*).
The Ozsváth and Schücking Metric is a solution for a vacuum in General Relativity: one with constant zero density. It is not a solution for a Quantum Vacuum.
The Ozsváth and Schücking Metric is considered to be very anti-Machian because according to Mach's Principle a Universe without any matter-energy sources should be flat and free of gravitation.
The Ozsváth and Schücking Metric is a solution that allows a universe to exist (within Einstein's General Relativity cosmology) with constant zero density and yet it has (Riemannian) curvature (wrinkles) that propagate in it.
I emphasize: in General Relativity a vacuum has constant zero density (*).
Before Ozsváth and Schücking came up with this solution there were many vacuum solutions that allowed such curvature (and hence gravitation) without sources, but they all contained singularities, and the interpretation was that the singularities hide real matter sources. The singularities are unphysical, so it was easier to explain away these vacuum solutions.
What is disturbing about Ozsváth and Schücking's metric is that it is a constant zero density solution that does not have any singularity, so it cannot be explained away using that argument.
You state "pp-waves are known to be approximations of waves generated by a source, at distances much greater than a wavelength", but the problem with the Ozsváth and Schücking's metric solution is that it allows a universe to exist where these waves exist in a vacuum with constant zero density, and without having been generated by any source.
It is the fact that this metric allows a universe to exist that has such waves in a vacuum with constant zero density and without having been generated by any source that is considered to be very anti-Machian.
Let's re-capitulate the versions of Mach's Principle listed by Samuel and Bondi:
Mach0: The universe, as represented by the average motion of distant galaxies, does not appear to rotate relative to local inertial frames.
Goedel's metric violates this
Mach7: If you take away all matter, there is no more space.
This is violated by all vacuum solutions, and is particularly violated by Ozsváth and Schücking's because it contains no singularities behind which matter can hide
PS: The discussion above is purely within General Relativity. When you talk about your EM ZPF you are discussing a different theory. In General Relativity there is no such thing as Quantum Vacuum. Quantum Mechanics is separate from General Relativity. If you consider the EM ZPF to have a ground state with non-zero-density or a fluctuating density around this ground state, then according to General Relativity, the EM ZPF is not a vacuum. According to General Relativity a vacuum has constant zero density. This is what is meant by Ozsváth and Schücking's solution: it is a solution for a universe with constant zero density.
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#2462 by graybeardsyseng on 26 Oct, 2017 13:08
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100 W/4 GHz dummy load from ebay
Peter
turns out to be not so good. An SWR of <1.2 was given.
Measured with the Windfreak Techn. SynthNV + directional coupler, relative to a 2 W termination of MiniCircuits.
It can be good, see for comparison the (lack of) reflection of the Centric RF 20 W termination, measured in the same setup.
Anyone with suggestions for a affordable 100 W / 4 GHZ termination?
Peter
I have had mixed results with this type of dummy load as well - looks like a RELM unit. Below about 1 Ghz most seem to work fairly well but not so good upwards toward 2 or 3 Ghz. Performance also tends to drop off as power increases towards max rating and in particularly if high power is dumped into the load for a long period of time.
Barry dummy loads have a pretty good reputation. If buying from Ebay (where I get most of my microwave items) look for an post which specifies it was actually tested and they specify at SWR it tested to. Here is a current example - preferably with test data.
https://www.ebay.com/itm/Barry-Dummy-Load-RF-Microwave-100-Watt-50-Ohm-DC-3GHz-SMA-M-SWR-1-17/272350381849?hash=item3f69590719:g:Ll8AAOSw0UdXvBYb
Not cheap and shipping is also rather high.
Here is an EMR dummy load but it only goes to 2.1 Ghz and 60 watts. Pretty good rep and they post the test data showing how the load preforms. Cost is much more reasonable.
https://www.ebay.com/itm/EMR-1640-Dummy-Load-RF-Microwave-60-Watt-50-Ohm-DC-2-1-GHz-SWR-1-1-TESTED/282525852544?hash=item41c7da6380:g:6NAAAOSw1BlZQate
Hope this helps
Herman
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#2463 by meberbs on 26 Oct, 2017 13:41
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I am guessing you haven't studied calculus, that is the incorrect way to take a derivative.Kinetic energy is not frame invariant, it is a function of velocity which is obviously not frame invariant. It is also not a linear function of velocity, so differences in kinetic energy also cannot be frame invariant.
The change in KE and work done can be frame invarient as follows.
Acceleration causes a change in velocity, which is frame invarient. All frames observe the same change in velocity, the same dV.
Using the dV, the change in KE can be calculated as dKE = m dV^2 / 2. Work done is then equal to dKE.
The correct answer is dKe/dV = m*v, which is a function of velocity, not difference in velocity, so by the third or fourth different method, it is still not frame invariant.
Please note, that at this point further "proofs" from you are pointless unless you directly point out something wrong with all of the proofs I have provided. My proofs include directly calculating kinetic energy using the equation for kinetic energy, and I also linked you to a first principles derivation of this equation. -
#2464 by Peter Lauwer on 26 Oct, 2017 13:45
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100 W/4 GHz dummy load from ebay
Peter,
turns out to be not so good. An SWR of <1.2 was given.
Measured with the Windfreak Techn. SynthNV + directional coupler, relative to a 2 W termination of MiniCircuits.
It can be good, see for comparison the (lack of) reflection of the Centric RF 20 W termination, measured in the same setup.
Anyone with suggestions for a affordable 100 W / 4 GHZ termination?
Peter
at which plane (connector) the calibration of the vna was done? Is it the connector at which the load is connected right now with inclusive the additional device shown in the picture? If not please try to calibrate at this connector. The SMA to N interface may also increase the VSWR level.
Hi X_RaY, the calibration was done with the 50Ω directly on the dir coupler. The m-to-m adapter visible in the picture was not between it. But that shouldn't matter with a termination, isn't it?
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#2465 by ThatOtherGuy on 26 Oct, 2017 14:24
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#2466 by ThatOtherGuy on 26 Oct, 2017 14:27
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100 W/4 GHz dummy load from ebay
Peter,
turns out to be not so good. An SWR of <1.2 was given.
Measured with the Windfreak Techn. SynthNV + directional coupler, relative to a 2 W termination of MiniCircuits.
It can be good, see for comparison the (lack of) reflection of the Centric RF 20 W termination, measured in the same setup.
Anyone with suggestions for a affordable 100 W / 4 GHZ termination?
Peter
at which plane (connector) the calibration of the vna was done? Is it the connector at which the load is connected right now with inclusive the additional device shown in the picture? If not please try to calibrate at this connector. The SMA to N interface may also increase the VSWR level.
Hi X_RaY, the calibration was done with the 50Ω directly on the dir coupler. The m-to-m adapter visible in the picture was not between it. But that shouldn't matter with a termination, isn't it?
as x_ray wrote, even an m2m adapter may cause problems and should be carefully measured as well
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#2467 by flux_capacitor on 26 Oct, 2017 15:24
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{snip}
The singularity (at r=0) in Schwarzschild 's solution cannot be a true singularity. It must be an approximation. It must be hiding a true mass source [alternatively, flux-capacitor posted a solution by Andrei Sakharov (?) positing that it hides a wormhole].
The answer lays in topology.
Actually, Sakharov's hypothesis about wormholes was, although clever and ahead of time, just an idea without much mathematical demonstration. There are more recent (2015) mathematical demonstration clearly showing that the so-called "true singularity" at r = 0 can be cancelled (in fact, more precisely, does not exist) "within" a black hole. Because a black hole has no interior.
First, Karl Schwarzschild himself posited r > 0. r cannot go negative according to Schwarzschild. It is clearly written in his two founding papers, attached to this post in both German and English, that almost nobody ever has read in their original 1916 form nor in their more recent English translation. That is to say, space coordinates are always real. Doing analytic continuation for r < 0 is nothing but allowing space coordinates to become imaginary. In other words, it is allowing someone to make distance measurements of a hypersurface, but outside of that hypersurface. It is meaningless.
Second, and this is related as this choice to operate using real quantities and not imaginary ones, to stay in the real, laboratory physics, Schwarzschild considered only the metric signature (+ – – –)
Third, the main error everyone did and still does is to posit r is a radius, i.e. a radial distance from a center point, like in a sphere. But r is no a radius, it is a space marker. For r Schwarzschild used the words "polar coordinates" (Polarkoordinaten):
But Schwarzschild introduces what he calls an "auxiliary quantity" (Hilfsgröße) R, and it is through it that he expresses his "exterior" solution in his first paper in January 1916:
So the variable r chosen by Schwarzschild is strictly positive, and the intermediate quantity R is not free but has a lower limit α (which will later be called the "Schwarzschild radius" mostly written Rs):
r = Rs was at first considered as a "true singularity" but is has been shown after Schwarzschild's death that is is only a "coordinate singularity" that can be eliminated through various changes of coordinates.
What about r = 0, that is to say R = Rs ?
It has been shown (reference) that a change of coordinates can eliminate this "true" singularity, because such singularity is not really "true" it is caused by a wrong choice of local topology.
The "magical" change of variable is to take:
r = Rs (1 + Log ch ρ)
To explain quickly how this is done mathematically without resorting to the full maths of the peer-reviewed paper, I will decrease the number of dimensions so everyone can visualize. The Schwarzschild exterior metric describes a 4D object:
Removing the part of the metric related to time, keeping only the spatial part of the metric, we get the description of a 3D hypersurface:
We continue and remove one space dimension, to get a 2D surface:
Studying the surface described by this metric, it is easy to show it corresponds to a parabola:
Applying a rotational symmetry to the parabola around the z-axis, returning to a 2D surface embedded in a higher dimensional 3D space, one gets the shape of a diabolo:
which connects two spaces together through a throat circle:
The diabolo is represented above with two circular boundaries on both sides to better show the general shape of the object, but this surface is actually borderless as it connects two flat spaces:
That is to say in higher dimensions, this bridge connects two Minkowski spaces together through a throat surface.
One fundamental question for the black hole model is: can we choose the topology of a hypersurface freely, or does the topology of a hypersurface is intimately ensueing from its metric?
In the correct interpretation of the topology description of the object, contained in its metric, there is no center in this hypersurface. When you chose, like Schwarzschild, to keep real quantities everywhere, i.e. to be able to measure every point of the hypersurface in this solution of the Einstein field equations, everything becomes clear. r < 0 is not real. Space does not "become timelike" and t does not "become spacelike" anymore beyond this boundary. There is no more "central singularity". When you approach the event horizon of the black hole, if you make periodic measurements of the space marker r, you will notice that r is decreasing. Reaching the boundary, r has a minimal value. But going further ahead toward the (imaginary) "center" of the object, you will notice the space marker r is now growing again. The hypersurface is not contractible. r never becomes negative. All coordinates stay real.
There is also some successive work showing such event horizon acts as a one-way membrane with limited time transit for a test particle as well as for the point of view of a distant observer, contrary to the established "freeze frame" model of the black hole where time seems frozen according to a distant observer watching a test particle falling toward the event horizon (the fall of the test particle seems to take an infinite amount of time for the distant observer).
The key is to take radial frame-dragging into account during the gravitational collapse of a destabilized neutron star (which is never done classically, even for the Kerr black hole where only azimuthal, i.e. rotational frame-dragging within the ergosphere is considered, due to the dense body spinning around its axis). Indeed in a Machian sense, space is also dragged along the radial implosion of the star. If some of you express interest in this area I can detail further about this crucial point of infinite time vs finite time transit.
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#2468 by Rodal on 26 Oct, 2017 15:34
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Look at the equations (the math, instead of the words) you posted: Schwarzschild is using what is presently known as spherical coordinates
Third, the main error everyone did and still does is to posit r is a radius, i.e. a radial distance from a center point, like in a sphere. But r is no a radius, it is a space marker. For r Schwarzschild used the words "polar coordinates" (Polarkoordinaten):
...
http://mathworld.wolfram.com/SphericalCoordinates.html
instead of what is presently known as polar coordinates
http://mathworld.wolfram.com/PolarCoordinates.html
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#2469 by flux_capacitor on 26 Oct, 2017 15:43
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Look at the equations you posted: Schwarzschild is using what is presently known as spherical coordinates.
Third, the main error everyone did and still does is to posit r is a radius, i.e. a radial distance from a center point, like in a sphere. But r is no a radius, it is a space marker. For r Schwarzschild used the words "polar coordinates" (Polarkoordinaten):
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True. But this doesn't change the rest of the explanation, as for negative values of r space coordinates quantities cannot be real, so the choice of terms referring to the concept of a "distance from an origin" is still problematic for the description of r. Only ds has a physical meaning, i.e. a distance quantity. r and t are space and time markers, respectively. -
#2470 by Ricvil on 26 Oct, 2017 15:49
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We know the polarization state of photons ( clockwise and counterclockwise) are related with angular moment and helicity.
If a device changes these polarizations states of photons, them in fact some exchanges of angular moment occurs between them.
My question is.
TE and TM states in waveguides and cavities are other types of polarization, and if a device change one state to another, what type of exchange is occuring, or what is been transfered between the device and and the photons (modes)?
I'm asking because I can see a scenario where inside the fulstrum, two localized resonant modes (one at small flat end, and other at big flat end), can exchange energy like a DIMER, producing a oscilating center of mass.
In fact, this dimer is a asymmetrical dimer, with a TE and a TM localized resonant modes at same resonant frequency. -
#2471 by graybeardsyseng on 26 Oct, 2017 16:17
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https://www.ebay.com/itm/Barry-Dummy-Load-RF-Microwave-100-Watt-50-Ohm-DC-3GHz-SMA-M-SWR-1-17/272350381849?hash=item3f69590719:g:Ll8AAOSw0UdXvBYb
isn't this one the very same item ?
Well - yes it is apparently the same p/n item (if I am reading the p/n correctly on the one I found). BUT - the big difference is the unit I listed specifically provides the measured SWR when the unit was tested. The other unit is likely fine, it does say 100% tested, but does not say explicitly what the result of the test was.
I have had some bad experiences with items listed as Working - Tested - Works 100% or similar language which meant they had demonstrated functionality but not performance. I just like to have as much data as possible on something like this where I don't want to introduce any more problems or errors to a system or waste money. I usually ask a lot of questions of the vendor if possible when I am not sure. For both of these items I would likely question the vendors WRT what frequency the test was run at etc. BTW - there are other dummy loads where the response curve (SWR or RL) is shown vs frequency. Now that is helpful.
Fundamentally its a matter of 'you pay your money and you take your chance'.
For other users who may not be familiar with why dummy loads are important - you can destroy an amplifier or RF source very quickly by allowing it to feed RF into either an open circuit or a dummy load which doesn't function correctly . A few watts of RF - particularly at GHz frequencies, is all it takes.
graybeardsyseng
Herman -
#2472 by Rodal on 26 Oct, 2017 16:47
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What about r = 0, that is to say R = Rs ?
It has been shown (reference) that a change of coordinates can eliminate this "true" singularity, because such singularity is not really "true" it is caused by a wrong choice of local topology.
The "magical" change of variable is to take:
r = Rs (1 + Log ch ρ)
...
Unfortunately they (http://www.jp-petit.org/papers/cosmo/2015-ModPhysLettA.pdf) don't achieve this simply by a "magical" change in variables in a conventional metric cosmology.
There is a heavy price to pay.
It is not just topology of conventional spacetime manifolds that others [including Einstein -who read Schwarzchild in the original German] were unable to see.
Instead the way they manage to eliminate the singularity is by using a very unconventional "Janus" Cosmological Model of the universe composed by positive and negative energy (and mass if they own) particles, respectively described separate metrics g(+)µν and g(−)µν , solutions of a coupled field equation system. https://forum.nasaspaceflight.com/index.php?topic=43501.msg1709505#msg1709505
Their model implies injection of negative energy (and mass if they own) particles in spacetime, considered as a
manifold plus two metrics . They also had to assume that particles of opposite masses do not interact neither by electromagnetic forces nor strong or weak forces.
There is no physical evidence for such a cosmological unconventional model composed by positive and negative energy (and mass if they own) particles, respectively described separate metrics g(+)µν and g(−)µν
So, they replace one problem deep inside the event horizon of a black hole (the singularity at r=0) with another problem (2 separate metrics, and existence of negative energy) for the whole naked Universe, -which we can see- for which we have no cosmological experimental evidence of existence (aside from a very narrow context: an interpretation of the Casimir effect). -
#2473 by X_RaY on 26 Oct, 2017 17:23
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Nothing is perfect. This type of connectors can cause reflections and small amount of impedance mismatch.100 W/4 GHz dummy load from ebay
Peter,
turns out to be not so good. An SWR of <1.2 was given.
Measured with the Windfreak Techn. SynthNV + directional coupler, relative to a 2 W termination of MiniCircuits.
It can be good, see for comparison the (lack of) reflection of the Centric RF 20 W termination, measured in the same setup.
Anyone with suggestions for a affordable 100 W / 4 GHZ termination?
Peter
at which plane (connector) the calibration of the vna was done? Is it the connector at which the load is connected right now with inclusive the additional device shown in the picture? If not please try to calibrate at this connector. The SMA to N interface may also increase the VSWR level.
Hi X_RaY, the calibration was done with the 50Ω directly on the dir coupler. The m-to-m adapter visible in the picture was not between it. But that shouldn't matter with a termination, isn't it?
https://www.rfmw.com/data/Carlisle_RF_Microwave_Adapters.pdf
The load itself also cannot be described as a pure R component. Because of the mechanically parts C and L are not exact zero (feedline, resistor caps and so on), their values are frequency dependent. All this together can lead to the mismatch you observe.
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#2474 by Bob012345 on 26 Oct, 2017 17:25
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Kinetic energy is not frame invariant, it is a function of velocity which is obviously not frame invariant. It is also not a linear function of velocity, so differences in kinetic energy also cannot be frame invariant.
The change in KE and work done can be frame invarient as follows.
Acceleration causes a change in velocity, which is frame invarient. All frames observe the same change in velocity, the same dV.
Using the dV, the change in KE can be calculated as dKE = m dV^2 / 2. Work done is then equal to dKE.
Therefore dV, dKE & work done are now frame invarient.
QED
Sorry, but it's m*v0*dV + (m dV^2) /2 using your notation where v0 is the initial velocity as seen by an arbitrary observer. I assume by dV you really simply mean the change in velocity.
The work done is the change in kinetic energy but in general it's computed as 0.5*m*(v2^2 - v1^2) not 0.5*m*(v2 -v1)^2 where 1,2 are initial and final velocities as seen by some observer. Your formula gives 0.5*m*(v2^2 - 2*v2*v1 + v1^2) which amounts to the sum of the kinetic energies minus an interaction term.
I can write it out in your notation which is v1 = v0 and v2= v0 + dV. Then, the work energy theorem becomes Work = 0.5*m*(v0 + dV)^2 - 0.5*m*v0^2 which reduces to m*v0*dV + (m dV^2) /2. So all observers do agree on the second term which is the work done starting from rest and disagree on the first term which depends on the relative velocity of the observer. So, there is a frame invariant part and a non frame invariant part.
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#2475 by Bob012345 on 26 Oct, 2017 18:09
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In the typical EMDrive cavity, what typical values of radiation pressure exist on the endplates? I'm guessing it's something on the order of Q* (power/c )/area where area is average area of the endplates. Is that anywhere close to being reasonable? I'm asking about pressure, not thrust. Thanks.
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#2476 by flux_capacitor on 26 Oct, 2017 18:12
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....
What about r = 0, that is to say R = Rs ?
It has been shown (reference) that a change of coordinates can eliminate this "true" singularity, because such singularity is not really "true" it is caused by a wrong choice of local topology.
The "magical" change of variable is to take:
r = Rs (1 + Log ch ρ)
...
Unfortunately they (http://www.jp-petit.org/papers/cosmo/2015-ModPhysLettA.pdf) don't achieve this simply by a "magical" change in variables in a conventional metric cosmology.
There is a heavy price to pay.
It is not just topology of conventional spacetime manifolds that others were unable to see.
Instead the way they manage to eliminate the singularity is by using a very unconventional "Janus" Cosmological Model of the universe composed by positive and negative energy (and mass if they own) particles, respectively described separate metrics g(+)µν and g(−)µν , solutions of a coupled field equation system. https://forum.nasaspaceflight.com/index.php?topic=43501.msg1709505#msg1709505
Two distincts things there.
The authors indeed propose both a cosmological model involving negative mass; and a black hole model where the central singularity is eliminated with a change of variable. Both models are of course compatible (i.e. when used together) but one or the other can also exist without the other one being true.
Yes, the "diabolo topology" strongly militates for a connection of two distinct spacetimes. But it could also describe the connection of two distant regions of the same spacetime. Although the second proposition may seem problematic at first due to the lack of any observable white fountain in the universe, this is not such a problem anymore when the process is considered as ephemeral, as radial frame-dragging implies a finite (and quite fast) process.
Both the cancellation of the central singularity (using the proper change of variable) and the finite-time transit (due to radial frame-dragging) are disconnected from the Janus cosmological model roots and could still be used in other frameworks (such as the brane cosmology you and others cited many times in these threads).
So again, the change of variable can be particularly interpreted as a mass inversion process in a finite time transit through an orbifold acting as a one-way membrane triggering CPT symmetry between two spacetimes in the framework of the Janus cosmological model, after Sakharov-Souriau-Petit. But such black hole model with no central singularity is not restricted to this particular cosmological model. They just fit well together and the paper you and I are referring to (Cancellation of the central singularity of the Schwarzschild solution with natural mass inversion process indeed makes use of the two models in an interweaved way, as implied by its title).QuoteTheir model implies injection of negative energy (and mass if they own) particles in spacetime, considered as a manifold plus two metrics . They also had to assume that particles of opposite masses do not interact neither by electromagnetic forces nor strong or weak forces.
This is because gravity is different in essence (Hinted already. But you do not agree. Although there may be different interpretations?). Gravity is spacetime curvature. Gravity is not mediated by particles following geodesics of spacetime, like photons. Consider models of gravity where one (not two!) manifold includes several metrics. Not a problem for mathematicians. Let's say there are only two metrics: in physics this is a particular form of bimetric gravity (also called "bigravity"). Negative energy photons and positive energy photons follow null-geodesics of their own metric, that preclude any electromagnetic interaction. This is different for gravity. Being part of the same universe, but not the same metric, positive and negative masses induce spacetime curvature that is felt by both species:
There you can understand that a mass is not intrinsically "negative" as a mass always induces a positive curvature in its own metric. The negative nature of gravity is also a relativity concept, as a mass is felt as being "negative" only from the point of view of an observer in the opposite metric (a hypothetical red observer made of "negative" mass in the image above would feel the blue Earth, although invisible, as being a concentration of negative mass, from his own point of view). This phenomenon can be described as "conjugate curvatures" or "conjugate geometries": Positive mass here, induces negative mass there.
But the 2D didactic image of a flat bedsheet or wire mesh being distorted is incomplete, as geodesics are different when a positive or a negative curvature is considered. Positive mass locally induces positive curvature in spacetime, i.e. where the sum of angles of a triangle > 180°); although negative mass locally induces negative curvature in spacetime where the sum of angles of a triangle < 180° in such a hyperbolic space the shape of a horse saddle:
So keeping in mind that in the Janus model, positive mass there induces negative curvature in the opposite metric, therefore some matter (in yellow below) flowing from one metric to the other (in purple) through a bridge located at the center of a destabilized neutron star (Schwarzschild black hole) can be represented in this 2D animation showing the evolution of conjugate curvatures through the process:
More explanations there to prevent this message from becoming too long.
Again, you see a mass is never intrinsically negative. Topology produces only apparent and relative negative curvatures. Instead of introducing "negative mass in cosmology" the Janus model explains the nature of negative spacetime curvature as being a relative concept between two metrics, so everything follows from topology. And is still described by field equations.QuoteThere is no physical evidence for such a cosmological unconventional model composed by positive and negative energy (and mass if they own) particles, respectively described separate metrics g(+)µν and g(−)µν
So, they replace one problem deep inside the event horizon of a black hole (the singularity at r=0) with another problem (2 separate metrics, and existence of negative energy) for the whole naked Universe, -which we can see- for which we have no cosmological experimental evidence of existence (aside from a very narrow context: an interpretation of the Casimir effect).
The existence of singularities are a problem.
The introduction of negative energy in cosmology is not a problem: it is rather the non-observation of theoretically possible negative energy states that is a problem.
Although being theoretically predicted, scientists are satisfied deciding that negative mass does not exist in physics, not only because it is not observed directly, but because of the preposterous Runaway motion paradox arising in general relativity, as described by Hermann Bondi in 1957. It is easier that way, otherwise too much problem.
But the complete Poincaré group describes negative energy and negative mass particles as being real, they are simply the counterpart of all known positive energy particles: electrons, protons, neutrons, photons, neutrinos, etc. but with a negative energy. Discarding this possibility on the altar of Occam's razor is too easy. On the contrary, WIMPs superparticles following from supersymmetry (SuSy) should now be detected already. 40 years AWOL but still considered as "almost around the corner" and "the most plausible explanation for dark matter".
As for the lack of "evidence", your mileage may vary. Any respectable theory has to:
1- be mathematically sound
2- be in agreement with observations
3- make successful predictions
4- be falsifiable with experiments
If a theory agrees with these four points, it should be considered and evaluated accordingly. -
#2477 by Rodal on 26 Oct, 2017 18:44
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But (http://www.jp-petit.org/papers/cosmo/2015-ModPhysLettA.pdf) the spatial coordinate transformation of the central singularity starts with the preamble:
Both the cancellation of the central singularity (using the proper change of variable) and the finite-time transit (due to radial frame-dragging) are disconnected from the Janus cosmological model roots and could still be used in other frameworks (such as the brane cosmology you and others cited many times in these threads).
...QuoteNow, let us focus on the space part of Schwarzschild’s line element, limited to {r, ϕ} coordinate
(Eq. 9).
and eventually recognize thatQuoteWe have to deal with 4D spacetime, not 3D spacetime, which is just a didactic image of such geometric structure.
In General Relativity 4D spacetime is a connected unity (you said previously that what matters is ds). In order to consider 4D spacetime they have to consider the Janus cosmological model bimetric, which includes the negative energy. So the cancellation of the singularity in 4D spacetime [what we are interested in, in the real universe] needs the assumption of the Janus cosmological model bimetric, including the negative energy.
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#2478 by flux_capacitor on 26 Oct, 2017 19:11
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...
But (http://www.jp-petit.org/papers/cosmo/2015-ModPhysLettA.pdf) the spatial coordinate transformation of the central singularity starts with the preamble:
Both the cancellation of the central singularity (using the proper change of variable) and the finite-time transit (due to radial frame-dragging) are disconnected from the Janus cosmological model roots and could still be used in other frameworks (such as the brane cosmology you and others cited many times in these threads).
...QuoteNow, let us focus on the space part of Schwarzschild’s line element, limited to {r, ϕ} coordinate
(Eq. 9).
and eventually recognize thatQuoteWe have to deal with 4D spacetime, not 3D spacetime, which is just a didactic image of such geometric structure.
In General Relativity 4D spacetime is a connected unity (you said previously that what matters is ds). In order to consider 4D spacetime they have to consider the Janus cosmological model bimetric, which includes the negative energy. So the cancellation of the singularity in 4D spacetime [what we are interested in, in the real universe] needs the assumption of the Janus cosmological model bimetric, including the negative energy.
You are right. At first, since the change of variable simply boils down in 2D to going from a surface the shape of a sphere, to a surface the shape of a half-torus (sort of) I was thinking that this trick could be used with any model, including a wormhole connecting two distant regions of the universe.
I read again the paper and in this model, this particular topology triggers at least PT-symmetry (both space and time inversions are tightly related) when crossing the throat. And probably complete CPT-symmetry (as suggested by Sakharov) as it has been shown elsewhere that this is indeed the case when one also includes the electric charge (charge conjugation or matter-antimatter symmetry) in a 5D spacetime, using the 5th Kaluza dimension.
Therefore in this model it is a matter of whether or not one considers that the physical meaning of T-symmetry is energy inversion (as showed with dynamical group theory) or if a particle with an opposite arrow of time is still a positive energy particle going backward in time. If T-symmetry physically reverses the mass of particles, and the bridge naturally (topologically) triggers such T-symmetry, then yes, the bridge triggers mass inversion. -
#2479 by Rodal on 26 Oct, 2017 19:19
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It is a very interesting discussion, thank you
Therefore in this model it is a matter of whether or not one considers that the physical meaning of T-symmetry is energy inversion (as showed with dynamical group theory) or if a particle with an opposite arrow of time is still a positive energy particle going backward in time. If T-symmetry physically reverses the mass of particles, and the bridge naturally (topologically) triggers such T-symmetry, then yes, the bridge triggers mass inversion.
, all part of:
, all part of: