The Podkletnov Effect

One of the most controversial subjects to talk about in physics is the "apparent gravity shielding" experiment done by Podkletnov, but I've talked on this blog about the importance of scientists boldly seeking anomalous data, and disregarding the theoretical mainstream, and I agree with Isaac Asimov who suggested that the cue for discovery in science is not "Eureka! I have it!", but "That's strange..". It seems recently that "That's strange.." is always interpreted as "That's dubious..". It is right that scientists should be sceptical, but pure scepticism is a sterile state. Podkletnov's paper was published in a good journal: Physica C, and it may disagree with standard theory, but in science experimental data comes before theory. Of course, the experiment could be wrong, and it doesn't help that it has not been reproduced in another lab (which it must be to be accepted) but this does not mean that Podkletnov's results are not reproduceable, the published accounts of the attempts made so far say that they were not able to reproduce the experimental conditions.

The experiment was done by Podkletnov and his team in Finland (see Podkletnov, 1992, 1997). They had a half-superconducting disc with a radius of 13.5 cm. They cooled it down to 70 Kelvin (-203oC) in a cryostat, so that the upper part only was superconducting and then levitated it using a magnetic field. They then applied an AC magnetic field of high frequency (MHz) which accelerated the disc. A team member was smoking when he shouldn't have been and they noticed that the smoke was rising over the cryostat. After investigation, they noticed that when the disc was accelerating due to the AC field, but not spinning, objects above the disc lost 0.05%-0.06% of their weight. When they spun the disc at 5000 rpm they noticed a larger weight loss of 0.6-2%. The greatest weight loss occured when they slowed the disc to 3000-3300 rpm and it visibly vibrated. The effect was independent of the test mass’s composition and was not due to moving air since it persisted when the test mass was encased in glass. It was not magnetic because it remained when a metal screen was placed between the disc and the masses.

I've been cautiously fascinated by this experiment for years. I think it's important when thinking about physics not to try to "Play Mathematical Games" or "Guess the Mind of God" as many theoretical physicists do, but instead to think within the context of real experiments, and to get new physics they have to be anomalous ones. I eventually found that MiHsC predicts something like the behaviour seen by Podkletnov. Consider an object suspended above the disc. When you cool its environment, nearby accelerations reduce, the Unruh waves it sees lengthen, more are disallowed by MiHsC's Hubble-scale Casimir effect and its inertia drops. Then the AC magnetic field accelerates the disc, so the Unruh waves seen by the object become shorter, fewer are disallowed and its inertia increases. This means it becomes less responsive to gravity: an apparent loss of weight. MiHsC predicts a weight loss of 0.03% which is not far from that seen (see McCulloch, 2011, note: I made a factor of two error in the published version, the arxiv version is alright).

When the disc was spun, further vibrations occurred and these are not quantifiable in the same way, or at least I don't know how to do it, so it is unclear so far whether MiHsC could predict the larger weight losses or not. Another thing that bothers me is that the column of weight loss seen by Podkletnov seemed to extend upwards indefinately. Was he forming and firing Unruh waves upwards??

I think this experiment is worth redoing. There is a chance that it is saying that something is going on that is a bit like MiHsC and I would love to have more published results to think about.

References

Podkletnov, E.E, and R. Nieminen, 1992. A possibility of gravitational shielding by bulk YBa2Cu3O7-x superconductor. Physica C, 203, 441-444.

Podkletnov, E.E., 1997. Weak gravitational shielding properties of composite bulk YBa2Cu3O7-x superconductor below 70K under e.m. field. http://arxiv.org/abs/cond-mat/9701074

McCulloch, M.E., 2011. Can the Podkletnov effect be explained by quantised inertia? Physics Procedia, 20, 134-139. http://arxiv.org/abs/1108.3488

Cosmic acceleration: no need for dark energy.

The Canadian astronaut Chris Hadfield recently made a brilliant musical video of David Bowie's Space Oddity on the International Space Station. The imagine of his guitar drifting lazily down the central spine of the station gave a nice demonstration of Newton's first law: the one that says that objects travel at constant velocity unless something pushes them. As I've discussed in a previous blog, MiHsC has a slightly different prediction, that nicely does away with the need for dark energy.

Imagine that one of Chris' fellow astronauts launches his guitar into deep space. According to MiHsC, as he launches it, its high acceleration relative to nearby matter means that the guitar sees Unruh radiation with a short wavelength, but as it moves into deep space, away from the gravity of the Sun, it's acceleration becomes tiny and the Unruh waves it sees become longer. Eventually, out beyond Pluto they lengthen to the Hubble scale (Theta), and when they exceed this scale they can never be observed. So following Mach (who said that what you cannot see in principle does not exist) the Unruh waves dissapear in a puff of logic (or an exchange between information and energy). This is also a bit like the notes on a guitar: there is a lowest note with a wavelength that is twice the length of the strings. So MiHsC predicts that in deep space the guitar's inertial mass fails. This makes it easier for the guitar to be accelerated again even by the gravity of the distant Sun, so it accelerates, the Unruh waves shorten, the guitar gets its inertia back, so its acceleration slows, it looses inertia .. and so on.

There is a competition here between the inertial failure caused by MiHsC's Hubble-scale Casimir effect and the inertia regained after the lower inertia causes renewed acceleration. MiHsC predicts that a balance exists between these two effects (and balances are the things that last) at a tiny acceleration of 2c^2/Theta = 6.7x10^-10 m/s^2. This acceleration is so small it would produce a speed change from zero to 60 miles per hour in 8500 years, or from zero to the speed of light in 13 billion years (the supposed age of the universe).. The point is that this minimum cosmic acceleration predicted by MiHsC is close to the recently observed cosmic acceleration, the one that is usually attributed ad hoc to dark energy. MiHsC predicts it far more elegantly from a simple philosophy (see the paper below for more details).

McCulloch, M.E., 2010. Minimum accelerations from quantised inertia. EPL, 90, 29001. Preprint: http://arxiv.org/abs/1004.3303

Entropy and Surface Area

An important part of science, a fun part, is following up interesting observations in the hope that something will come of it. One great paper I enjoyed reading was full of observations like this. It was by A. Unzicker (arxiv:gr-qc/0702009v6) and he gives a theory-independent overview of observations regarding gravity.

One observation he mentioned is either a meaningless coincidence, which it could be, or means something interesting. The idea is that if you approximate the area of galaxies by 2*pi*r^2, where r is the galactic radius, take r as 10,000 pc and assume, realistically, that there are 1.25*10^11 galaxies in the Hubble volume (Hubble Space Telescope, 1999). You then get a total area of 7*10^52 m^2 (with a big error bar). This is close to the surface area of the Hubble volume, which is 4*pi*R^2 = 2.3*10^53 m^2 (another big error bar) where R is the Hubble radius. He says this is an astonishing coincidence of the present epoch, since galaxies are not thought to change in size (p15). It sounds somewhat similar to the holographic principle too, in that the entropy or disorder in the universe (which I take to be proportional to the surface area between matter and empty space) is determined by the surface area of the bounding surface.

MiHsC agrees with this sort of picture, though I haven't modelled it in this context yet. In MiHsC the inertial mass increases as the Hubble volume expands. This means that stars at the edge of galaxies should progressively, as cosmic time goes on, have more inertial mass and be less willing to be bent into orbit by gravity, so galaxies should expand with time to follow the expansion of the Hubble volume (I don't know yet what the exact dependence would be). If it is linear, then no matter what epoch you're in, the equivalence between galactic surface areas and the Hubble surface area would be true: it is then no coincidence.

Courage from below, humility from on high.

I saw Julian Assange's 2012 Christmas balcony speech and he said two things that resonated with me: "Civilisations are only as good as their ideas, and good ideas do not come when journalists and academics are timid". Assange represents a fork in the road of our culture. Can we maintain a new freedom of information for the masses, a new Gutenberg revolution, and raise our culture to a higher level? Or not?

In comparison we physicists have it easy: when you try to determine the truth about the universe, it doesn't get mad. However, there is something that physicists should be willing to do that is a little scary: make testable predictions. The scary part is the possibility of being wrong. Many modern theories do not make testable predictions and they remind me of the futile debates in the dark ages about whether God was in three parts or one. We had learned by the time of Galileo and Newton that, although testing theories is an excruciating process, theories based on old books rather than experiments are useless. Recently this has been forgotten by some theorists.

What is called for in physics, and politics too, is intellectual courage from people low down in the hierarchy and, especially, a little humility from those at the top (it has always been so). It's time the authorities admitted that they do not know what they think they know, and allowed the facts to be discussed by all in a freer manner. We will all gain from this.

The only wisdom we can hope to acquire is the wisdom of humility: humility is endless.
T.S. Eliot