I've suggested (& published in 21 journal papers) a new theory called quantised inertia (or MiHsC) that assumes that inertia is caused by relativistic horizons damping quantum fields. It predicts galaxy rotation, cosmic acceleration & the emdrive without any dark stuff or adjustment. My Plymouth University webpage is here, I've written a book called Physics from the Edge and I'm on twitter as @memcculloch

Friday, 26 August 2016

Dragonfly 44: a fudge too far.

Yesterday, a few people online kindly sent me the news that a galaxy called Dragonfly 44 has been found apparently containing 99.99% of the so-called 'dark matter' (see reference). Many, for example Sean Carroll, said that this supports the dark matter hypothesis. However, in reality it worsens the outlook for dark matter, which has to be added in different ad hoc amounts to each galaxy, in huge amounts to this one, and so it further supports MiHsC (quantised inertia) which works for all galaxies without any arbitrary tuning needed...

For each separate galaxy they find, the darkmatterists have to add dark matter in different amounts, 90% for the Milky Way, 99% for dwarf satellite galaxies, 99.99% for this one. This number is arbitrary, they chose it incestuously to make general relativity work for the data, and it has no reason behind it except to save GR. That means that the dark matter hypothesis is not only not falsifiable (you can look for dark matter for ever), it is also not predictive. Given the visible light distribution, dark matter cannot predict the velocity of stars. So dark matter is a bit like Peeves at Hogwarts: useless, but you can't get rid of him.

In contrast MoND and quantised inertia / MiHsC are both predictive. Given the visible mass M (it's best to base theories on visible stuff) MoND says the stellar velocity is v=(GMa0)^1/4 (a0 is a fitting parameter) and MiHsC says v=(2GMc^2/Hubblescale)^1/4 (no fitting parameter, and a slighly higher velocity, see equation below) and both predict the velocity dispersion of Dragonfly 44 within the uncertainty and without the need for any dark matter.

The important advantage of MiHsC over MoND is that MiHsC has no adjustability, at all! MoND was an inspiration for me, but it is not a theory, it is an empirical formula that happens to fit galaxy rotation if you 'tune' the adjustable parameter a0 against the data, so it is not surprising that it fits the data, because it has been fitted to it. The parameter a0 has no 'physical reason'. MoND is a bit like an engineering formula with its tune-able a0. In contrast MiHsC has been derived from first principles, says the velocity has to be one value with no tuning possible, and every parameter in the MiHsC formula below is known from observation and is there for a good physical reason, so it is remarkable that it works on all galaxies including Dragonfly 44:

In this way MiHsC resembles special relativity in that there is no arbitrariness about it, no input numbers, but it will need input from better mathematicians than me to properly describe higher order effects due to the interaction of Unruh waves with relativistic horizons or cavities.

A loose analogy to this crisis in astrophysics would be holding a competition to see who can make a shoe to fit a foot they've only seen from a distance (like a theory that must predict galaxy rotation from observed quantities to be useful). Shoemaker 1 comes with his shoe, says 'It fits', but you see nothing. 'It's invisible!' he says (GR and dark matter). Shoemaker 2 comes with a shoe that has an adjustable strap and he adjusts the strap to fit it (MoND). This is better. Then shoemaker 3 comes with one unadjustable shoe, and it fits (MiHsC). Obviously, the third shoemaker is the best one.

I cannot emphasise enough the difference between tunable theories like dark matter, and to a lesser extent MoND, and a non-tunable theory like MiHsC. Only a non-tunable theory gives a real understanding of the physics.


van Dokkum, P., 2016. A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra Diffuse Galaxy Dragonfly 44. http://arxiv.org/abs/1606.06291

McCulloch, M.E., 2012. Testing quantised inertia on galactic scales. Astrophys. & Sp.Sci., 342 (2), 575-578. http://arxiv.org/abs/1207.7007


Zephir said...

If I understand it well, the problem of MoND / MiHsC just is, they predict fixed ratio of visible/dark matter? Fortunately the calculation of baryonic mass in Dragonfly 44 is based entirely on the luminosity of the galaxy, so it's premature to say its mass is almost entirely made of dark matter.

Mike McCulloch said...

I'm glad you asked that: I'm afraid you've misunderstood. Firstly they do not predict dark matter (DM) at all, they change the physics instead. Secondly they do not predict a fixed 'apparent' ratio of VisibleM/DM, the 'apparent fraction' of DM increases with M, but again it is the physics that is changing. Thirdly, MoND has a 'problem' in that the fitting parameter a0 is empirical and unexplained and that is unsatisfactory, but MiHsC has no such problem. Hope that helps..

Zephir said...

Well, it didn't help very much... Now I'm talking about amount of DM like about amount of artifacts, which violate the general relativity (like the anomalous lensing or momentum connected with anomalous velocity curves). I don't ask about its physical origin at all in this moment.

But once we have dark matter without observable one, then all theories which are relying on modification of relativity with changing physics (with ad-hoced parameters or without them) get doomed with no mercy. BTW the MoND theory parameter is not so ad-hoced as you may think, as the acceleration parameter a0 can be estimated easily as the product of Hubble constant and speed of light, i.e. the result of omnidirectional expansion of space-time.

Mike McCulloch said...

There is maybe a language barrier, but I can't understand your objection. I can assume there is no dark matter. Also, MoND's a0 was determined empirically by comparing to galaxies. It's easy then to say: 'it's in the ballpark of cosmic acceleration', but you have to suggest a mechanism to explain why, otherwise you don't know anything and it could be a coincidence. MiHsC does suggest a mechanism and MoND never successfully did: Milgom rejected Unruh radiation as being isotropic. Once you have such a mechanism, MiHsC, then you can predict many things in other regimes, such cosmic acceleration, the flyby anomaly, the emdrive the proton radius that MoND can not. Physics needs to have exact mechanisms, not empirical formulae, otherwise it is just engineering and not predictive beyond a narrow range.

Mike McCulloch said...

Let me put it this way: How would you feel about Einstein's theories if, instead of E=mc^2 he'd come up with E=1.578mc^2 and said 'well, 1.578 is of the order of pi'?

Zephir said...

/* but you have to suggest a mechanism to explain why */

It just follows from the above product of Hubble constant and speed of light - or not? The anomalous deceleration of Pioneer spaceprobes can be explained in just the way, the light exchanged between Earth and spaceprobe isn't able to measure with expanding space between them. In dense aether model the space-time expansion is virtual result of light scattering with the quantum field (density fluctuations of vacuum responsible for (isotropic) CMB noise), which also explains the deeper connection of MoND and MiHsC theories. That is to say, I'm not serving as an advocate of any theory here - I just want to understand their both strong, both weak features, i.e. both common aspects, both mutual inconsistencies.

Zephir said...

/* but I can't understand your objection. I can assume there is no dark matter */

Under situation, when we don't understand (or at least intersubjectively accept) the nature of dark matter, then the "dark matter" denomination serves as a phenomenological description of all observations, which don't fulfill the established theories at astronomic scales.

This doesn't imply, that the dark matter is actually formed with some massive particles or just field. In reality it can be formed with something inbetween or it may be of composite character - which would mean, many particular theories may be applicable here at the same moment in some mixing ratio.

For me it just seems, that the MiHsC is more advanced than MoND in this moment, but because both model depend on relativity, they both don't work well until the dark matter is forming filaments (sparse cold dark matter scenario for spherically asymmetric solutions) or it exhibits cohesive properties (which is the case of Bullet cluster or let say Dragonfly 44 galaxy, i.e. the case of hot dark matter). The both apply to warm dark matter scenarios at best.

benjamin said...

Hello Mike,

I was wondering if you had any recent results to share about gravitational lensing effects. I note that you had a post a while ago about your thoughts on this, but I didn't see anything recently. I ask, because I'd seen this category of evidence (Bullet Cluster and others) cited as a real knock-down argument in favour of the presence of true mass, and therefore for dark matter or something like it. I'm just an interested layman, so I can't really evaluate how strong this argument is (nor can I work out what might be the implications of MiHsC for galactic-scale deflection of light, hah.)

qraal said...

Hey Mike,
Cannae are launching a CubeSat test of their thruster, which is a variation on the EM Drive. We might see some slam-dunk verification of your theory before too long :-)

Mike McCulloch said...

qraal: I'm very happy that Cannae are doing this crucial experiment. Good luck to them! I need to know their specifications so I can make a prediction.

Analytic D said...


You just need behavior that affects light like GR mass affects light. Horizon mechanics definitely leave room for such behavior.

benjamin said...

@Analytic D

Thanks, I thought it would be something like that. I mean, it would make sense that light bent by gravity would follow the same rules as mass. I just don't have enough of a feel for it to be sure of my guesses.

tyy said...

Your MiHsC says this, and MiHsC says that. All derived from Unruh effect and "Hubble scale Casimir effect" (whatever balooney that is)

Let me only say this: I suspect that you do not understand what Unruh effect actually is, what it predicts and what the scale of the phenomenon (if ever observed) would be.

Zephir said...

My suspicion is similar, because the Unruh radiation is luminal in essence, so it cannot be applied as a causual explanation of anything at the cosmological scales. This still doesn't mean, that your work has no practical merit, but I would reconsider its physical intepretation for to avoid the epicycle glitch: the numeric agreement of explanation with reality still doesn't means, that the reality works according to this agreement, once the observational perspective gets inverted.