Tweaking mass

In the past, the 'high level' properties of inertial mass and gravitational mass have not been well understood, but properties like this are always caused at a deeper level, and if you can understand and access that deeper level it gives you a handle to control them.

MiHsC shows that if you assume that inertia is due to Unruh radiation (subject to a Hubble-scale Casimir effect) you can predict anomalies observed in low acceleration environments (eg: galaxy rotation, cosmic acceleration). So there is evidence for MiHsC and since it points at Unruh radiation as a cause it could give us a handle on mass: a way to control it via something we know about: radiation. Admittedly, Unruh radiation is different from the usual stuff, but it can be made by mutual accelerations.

To put this in a practical context: at the equator, the gravitational force pulling, say, an elephant, down is about 365 times stronger than the centrifugal (inertial) force pushing it up. If MiHsC is right, it predicts that if we could fire enough extra Unruh radiation at the elephant to increase its inertial mass 365-fold, it should then lift off. (it may also move sideways against the Earth's spin to conserve momentum).

The first indications of this may have been seen in Podkletnov's experiment where he accelerated (in his case, spun) a disc and saw a weight loss in objects suspended above it. A few more Unruh waves and maybe the rocket era would be over.

The best way to convince others is with simple repeatable experiments, and one such experiment was recently pointed out to me by J. Tippett (he'd seen it described by Modanese in the book referenced below, see page 13). In the experiment a cold superconductor was levitated above a magnet and heated through its transition temperature. During the transition, 'transient weight losses' were seen in objects above the setup (in only 10% of the cases, so the phenomenon is not fully repeatable yet).

This experiment interests me because it fits roughly with MiHsC: the sudden loss of superconductivity would suddenly 'freeze' (ie: accelerate) electrons and transiently increase the mutual electron - object accelerations (a consistent result would need a uniform heating of the superconductor). The problem is: what is the electron acceleration in a superconductor? This is not well understood, and would need to be known to test MiHsC, but this experiment, at least, is easy to repeat, and the more repeats the better.

Reference

Modanese, G., and G.A. Robertson (eds), 2013. Gravity-Superconductor Interactions: theory and experiment.

Modanese G., Schnurer, J., 2001. Possible quantum gravity effects in a charged Bose condensate under variable e.m. field. Phys. Essays, 14: 94-105 (see part 4: experiment).

Evidence against dark matter

Galaxies spin so fast that the matter we can see lit up should be unable to hold them in by gravity and they should explode. Oddly they don't, so astronomers have speculated that dark (invisible) matter exists in the galaxies to hold them in with an extra gravitational force. This hypothesis has become entrenched in the astrophysics community to the exclusion of all other hypotheses despite a lack of evidence after decades of searching. This is perhaps because of its infinite flexibility which makes it difficult to disprove, so here I'd like to discuss some evidence against dark matter.

Dark matter usually only needs to be added to the edges of galaxies since in their centres they behave normally. Sanders and McGaugh (2002) pointed out that the radius at which galaxies start to spin too fast for their own good, and to need dark matter, is not a set distance, but it always occurs where the rotational acceleration drops below 1.2*10^-10 m/s^2: a very low acceleration called 'a0': a regime not previous encountered by our experiments. This is difficult to explain by dark matter - you'd have to invent a kind of matter that suddenly appears when accelerations are below this value.

Since dark matter is needed only at the galactic edge, its supporters need to have some new physics that keeps it smooth and diffuse. Brilliantly poking a hole in that, Scarpa et al. (2006) looked at globular clusters which are small dense congregations of stars within the galaxy, a bit like clumps of mistletoe in an oak tree. They found that whenever the 'internal' acceleration of these clusters drops below 1.2*10^-10 m/s^2 (a0 again) they spin far too fast to be stable, just like the full-sized galaxies, but in these globular clusters this anomaly cannot be explained by dark matter, since to work for galaxies dark matter must be smooth on these smaller scales.

An empirical hypothesis suggested by Mordehai Milgrom to explain galaxy rotation is called MoND (Modified Newtonian Dynamics). MoND doesn't have a physical model, but says that when total accelerations are below the critical acceleration a0 then either the gravitational mass of stars goes up, or their inertial mass goes down (in MoND you can choose either). MoND explains disc galaxies well, but it cannot explain these globular clusters because, as Scarpa et al. say: the external gravity field due to the Milky Way acting on these clusters is above a0 so MoND behaviour should not appear.

MiHsC has a better chance of explaining these clusters because in MiHsC the inertia of a star depends on the mutual accelerations between the star and all other stars, but the closer stars in the cluster have more weight in the calculation, so the crucial factor determining behaviour will be the internal accelerations, as observed. I need now to work out how to model these clusters with MiHsC. For modelling galaxies with MiHsC, see the paper: McCulloch (2012), or a brief summary.

An even better crucial test (simpler to model) would be to use the smallest globular clusters of all: wide binaries. Some binary stars with wide orbits have accelerations below a0, and they also seem to show anomalous behaviour (see Hernandez et al., 2011) but the data is noisy and not yet conclusive. Note: an even better test is the Alpha Centauri system.

References

Sanders. R.H., and S.S. McGaugh, 2002. Modified Newtonian Dynamics as an alternative to dark matter. Ann. Rev. Astro. and Astrop., 40, 263. Preprint. http://arxiv.org/astro-ph/0204521

Scarpa, R., G. Marconi, R. Gilmozzi, 2006. Globular clusters as a test for gravity in the weak acceleration regime. Proceedings of the 1st crisis in cosmology conference. Am. Inst. Phys Proceedings series, Vol. 822. Preprint. http://arxiv.org/astro-ph/0601581

McCulloch, M.E., 2012. Testing quantised inertia on galactic scales. Astrophysics and Space Science, Vol. 342, No. 2, 575-578. Preprint. http://arxiv.org/abs/1207.7007

Hernandez, X., M.A. Jimenez and C. Allen, 2011. Wide binaries as a critical test of classical gravity. Euro. Phys. J. C., 72, 1884. Preprint. http://arxiv.org/abs/1105.1873

The cosmos is mostly anomalous

I love the films of Woody Allen and one of the best quotes from Annie Hall is "That's one thing about intellectuals. They prove that you can be absolutely brilliant, and have no idea what's going on.".

This brings me to some comments from Hawking in the guardian today in which he says that the discovery of the Higgs boson is dissapointing because it reconfirms standard physics, and he ends asking us to look at the stars instead of our feet. Very inspiring, but although I love astronomy and long for humans to conquer space, I think that looking feetwards occasionally is a good thing: to make sure you're standing on a firm foundation and to learn a little humility.

It is true that standard particle physics happily found the Higgs, but particle physics reminds me of a specialised racing car. It works very well on a racetrack (or CERN), but drive it anywhere else and its shortcomings will be obvious. My point is that if Hawking wants some anomalies, he does not have far to look. The part of the cosmos we can predict with the standard model is about 4% of it. The other 96% of the universe is an anomaly (intriguingly correlated with low accelerations, and perhaps explained by MiHsC), but the racing drivers, with a myriad of fudges and fixes, have convinced themselves that the whole world is a racetrack and the mountains, bogs and ice cream vans you might think you see from time to time are just different kinds of circuit.

In the article Hawking also discusses the bets he has made. His bet against the discovery of the Higgs was a brave one, and firmly in the empirical traditions of science, but he also talks about his famous bet on whether 'information is lost in black holes'. What bothers me is that apparently this bet has been settled against him and he has given a baseball encyclopedia to John Preskill who apparently 'won'. I'm sure this 'decision' makes the theorists happy that they know what is going on, but it is complete hubris since the matter is untestable.

It is a shame Hawking didn't give Preskill a general encyclopedia since they could have looked up the middle ages and found out how much like their kind of thinking, the thinking was back then. In the middle ages intellectuals used to decide things with logic, starting from the bible and Aristotle, which made up their model of the world. What Hawking and his peers, all 'brilliant' intellectuals, are doing with the resolution of the black hole information paradox is deciding what the world is like, based on the standard model of physics, without any sort of experimental test. Is information lost in black holes? They say now that it is, based on the standard model, but no-one can observe a black hole well enough to find out, since they are annoyingly invisible, and to rely solely on a theory that only predicts 4% of the universe, is a good example of one of those times when they should have had a quick look at their feet. A more scientific investigation of information, involving an experiment, was attempted here.

This theory-only attitude bothers me since it is a backwards step from the 400 years of empirical science we have enjoyed since Francis Bacon, Galileo and Newton decided that the books were wrong and they asked nature using experiment instead. It is also interesting that just at the time that an elite of financiers are trying to escape into their own dream world, so again are the theoretical physicists. It is as if our civilisation is a coffee gone cold, and a skin is forming on top. It needs some heat and a stir!

Science, at bottom, is really anti-intellectual. It always distrusts pure reason, and demands the production of objective fact. H.L. Mencken, Minority Report.

The guardian article is here.

Gravity from uncertainty

My latest paper 'Gravity from the uncertainty principle' has just been published :) by the journal Astrophysics & Space Science. The paper is here (try the 'look inside' option).

The idea is as follows and was inspired partly by a course I teach at Plymouth on the mathematics of GPS positioning. I treat the size of the orbit of an object as an uncertainty in the position of each of its Planck masses (the dx from Heisenberg's uncertainty principle: dx.dp = hbar). So as an orbit shrinks in size, the uncertainty in position decreases, so the uncertainty in momentum (dp) must increase to compensate and this means that the uncertainty in the force must increase. When I sum this effect for all the possible interactions between the Planck masses in the two objects, Newton's gravity law appears.

This derivation of classical gravity from a principle of quantum mechanics, which takes just one page of maths, is interesting given that gravity and quantum mechanics have been thought to be incompatible. This model also suggests that only whole Planck masses gravitate, so as a test I've suggested that space dust should mostly be less than a Planck mass since only the larger dust would be gravitationally captured by larger masses.