Subject: Re: Comments on Woodward's Star Gate Review Article - space-time foam
"The customary way of making things larger is to blow them up. This is usually done by adding energy, sometimes explosively, to the object to be enlarged. It is worth noting that this process works for blowing things up in spacetime. Whether it will work for blowing up spacetime itself is another matter. The size of the wormholes of the putative quantum spacetime foam presumably are about the Planck length large – that is, about 10-33 cm across. This is about 20 orders of magnitude smaller than the classical electron radius and 18 orders of magnitude smaller than the diameter of nuclei. How do you blow up something so fantastically small? By smoking everything in its environs along with it. The two tools at our disposal to attempt this are the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Taking these devices (optimistically) to put about 10 Tev per interaction event at our disposal, we find in equivalent mass that gives us about 10-20 gm. This is roughly 15 orders of magnitude less that the mass of our transient wormholes to be ablated. Given present and foreseeable technology, this scheme is impossible. Moreover, the transient wormholes only exist for 10-43 seconds, making the temporal interaction cross-section hopelessly small." - JW
James's earlier remark that there may not be a spacetime foam is well taken. If gravity is an emergent low energy effective c-number field theory from the QCD/SU3 - weak SU2 vacuum superconductor then probably there isn't. However, in string-brane theory, gravity as a microscopic field has a Yukawa small scale metric like in Salam's 1973 f-gravity e.g.
G* = GNewton( 1 + ae^-r/b)
a ~ 10^40
b ~ 10^-14 cm? maybe 10^-16 cm
Therefore the effective Planck length at small scales would be LP* >> LP maybe as large as 10^-11 cm even larger?
http://www-conf.slac.stanford.edu/ssi/2005/lec_notes/Long/default.htm
This dramatically lowers the energies needed. The LHC data should give us information on this.
Gravity in large extra dimensions
n 1998, Nima Arkani-Hamed found himself pondering one of the conundrums of modern physics: why is gravity so much weaker than the other fundamental forces?
www.eurekalert.org/features/doe/2001.../dbnl-gil053102.php - The search for extra dimensions - physicsworld.com
The only force we can use to probe gravity-only extra dimensions is, of course, gravity itself. Remarkably we have almost no knowledge of gravity at ...
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symmetry - December 2005/January 2006 - the search for extra ...
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On Oct 4, 2010, at 9:48 AM, JACK SARFATTI wrote:
"That means, in turn, for example, that the mass of silica (glass) should be different from the masses of its silicon and oxygen constituents measured separately. This is not a small effect. Need I say, there is no evidence whatsoever that the masses of compounds depend on their indexes of refraction?" - JW
Jim's remark is not true if you put in the numbers and even accept his assumptions. Indices of refraction n of common materials are close to 1 even if as high as 10 the effect would be very tiny unless extraordinary attempt was made to detect it. Of course, no one has! Might be a good idea to look!
Take any material in the lab compute its total energy E, then multiply it by n^4G/c^4 to get an induced curvature - it will be tiny compared to the Earth's curvature.
Indeed, the induced curvature at Schwarzschild coordinate r outside of E
1/(radius of induced curvature)^2 ~ (n^4GE/c^4)r^-3
Furthermore, the dispersion in n needs to be included in any actual attempt to measure anomalous gravity. Basic point is that the effect is very tiny under normal conditions.
Lab objects are still test particles in the Earth's gravity field - their back-reaction is still relatively tiny.
It may be possible to detect this predicted anomalous gravity in short-lived atomic gas Bose-Einstein condensates and even in laser beams. Obviously no one has tried to because no one, until now, has even conceived of this possibility that needs to be checked out.
http://www.youtube.com/watch?v=2Z6UJbwxBZI
Superfluid helium "appears" to defy gravity - hmmm... "appears"?
Let us also not forget Ray Chiao's theory of electromagnetic-gravity wave transduction in a superconductor as well as Giovanni Modanese's model all suggesting anomalous gravity in Bose-Einstein condensates.
Refractive Index of Fe2O3, Iron Oxide
The refractive index (index of refraction) and extinction coefficient at 632.8 nm are 2.918 and 0.029. Below are files of complete refractive index and extinction coefficients.
http://www.filmetrics.com/refractive-index-database/Al0Ga100In50P50
Material Index
Vacuum
1.00000
Air at STP
1.00029
Ice
1.31
Water at 20 C
1.33
Acetone
1.36
Ethyl alcohol
1.36
Sugar solution(30%)
1.38
Fluorite
1.433
Fused quartz
1.46
Glycerine
1.473
Sugar solution (80%)
1.49
Typical crown glass
1.52
Crown glasses
1.52-1.62
Spectacle crown, C-1
1.523
Sodium chloride
1.54
Polystyrene
1.55-1.59
Carbon disulfide
1.63
Flint glasses
1.57-1.75
Heavy flint glass
1.65
Extra dense flint, EDF-3
1.7200
Methylene iodide
1.74
Sapphire
1.77
Rare earth flint
1.7-1.84
Lanthanum flint
1.82-1.98
Arsenic trisulfide glass
2.04
Diamond
2.417
On Oct 3, 2010, at 10:39 PM, JACK SARFATTI wrote:
PPS string theory has been attacked as not being background independent yet others say it's the only good theory for quantum gravity.
My point is that none of these key issues are well understood even by the experts and to hoist Jim by his own petard ;-) I quote his own very good points with which I agree:
"And you need a Jupiter mass – 2 X 1027 kg – concentrated in a region of small dimensions. A simple calculation assuming a throat diameter of, say, 10 meters and a wall thickness of a meter or so, leads to an exotic density of, ~ 1022 gm/cm3, that is, on the order of seven orders of magnitude greater than nuclear density. Similar densities, as a matter of idle interest, are required to make warp drives.
Faced with this fact, several responses are possible. Thorne’s recently expressed view is that the engineering of time machines (enabled by stargates) will require a profound understanding of the elusive, yet to be created theory of quantum gravity – if it can be done at all. And that may require evolution on our part comparable to the evolutionary distance between amoeba and us. That is, asking us to invent time machines is like asking amoeba to invent jet aircraft. This would mean that the clever aliens who have purportedly already done this are hundreds of millions of years more evolved than are we. A simpler, equivalent stance is to assert that anyone trying to make a stargate is an idiot. To propose that clever aliens have succeeded in this seemingly impossible task is just plain stupid. Working on the problem is a waste of time. Those of this view may be right. But if we adopt this view and abandon all work on the problem, we surely have no chance, however small, of succeeding.
Another approach to the problem of making stargates is to turn Thorne’s heuristic question around. Instead of asking what constraints the laws of physics place on clever aliens, we propose that clever aliens have made stargates and ask how, with plausible physics, might they have done so? Of course, allowing physics other than that endorsed by the mainstream opens the door to all sorts of excesses and stupidities. But if only mainstream physics were ever allowed, no progress on much of anything really interesting would ever be made. Arguably, a heuristic exercise of this sort has the same sort of value as that of Thorne and his graduate students years ago in that it illuminates what must be done to achieve the goal of stargates, thus shedding light on the requisite physics and thus on whether they will ever be made." -- JW
On Oct 3, 2010, at 10:29 PM, JACK SARFATTI wrote:
Salam's f-gravity is different from Einstein's gravity from a massless spin 2 graviton. In the former, it is due to a massive spin 2 meson.
On Oct 3, 2010, at 10:14 PM, JACK SARFATTI wrote:
"This means, if Equation (8) is correct, that the masses of things should depend on their indexes of refraction. That means, in turn, for example, that the mass of silica (glass) should be different from the masses of its silicon and oxygen constituents measured separately. This is not a small effect. Need I say, there is no evidence whatsoever that the masses of compounds depend on their indexes of refraction?" -- JW
The above argument is also questionable because the rest masses of electrons, nucleons etc. are determined from a completely different scale by the Higgs field Yukawa couplings for the leptons and quarks and by the zero point kinetic energy of the confined quarks for the nucleons as given in QCD. The index of refraction is a low energy emergent collective property of many electrons and atoms and indeed gravity itself is probably emergent. For warp drive and star gates we only need gravity in the low energy regime not at the small scale of the Compton wavelength of the electron for example.
On Oct 3, 2010, at 9:52 PM, JACK SARFATTI wrote:
"Working back through the argument, the first thing to note is that the substitution that leads to Equation (8) is not valid. Neither is it supported by the facts of observation. It’s not valid because the polarizable vacuum model is not background independent, and any plausible theory that is physically equivalent to general relativity must be background independent." -- JW
Jim's basic error is to make apriori arguments on an empirical issue.
There are no relevant facts of observation here apart from flying saucers, which, if they are real, refute Jim's argument by his own admission - see above.
I mean no one has yet made an ultra high temperature superconducting meta-material in which n ~ 10^10 with both negative permittivity and permeability in some range of frequencies and wave vectors for non-radiative near EM fields.
Yet, there are tantalizing controversial claims of anomalous gravity from superconductors.
Second, the appeal to background independence is spurious as is well known from the fact, as an example, that crystals spontaneously break translational symmetry. In the same way, we can have a spontaneous breakdown of background independence in the superconductor ground state without violating the background independence of the Einstein field equations. James has confused the symmetries of the field equations with the symmetries of their solutions!
One can see the error in James's argument by looking at the standard cosmological solution in which there is a preferred foliation in which the Cosmic Microwave Background (CMB) is maximally isotropic - even though the field equations have no preferred global frame. The temperature of the CMB is an objective measure of global cosmic time.
That said, Jim's conclusion in the end may be correct as I have always said, but that is an empirical issue.
More comments later as I am watching "Rubicon" on TV. ;-)