One of the advantages that MiHsC (Modified inertia due to a Hubble-scale Casimir effect) has over other hypotheses like dark matter is that it makes successful predictions of galaxy rotation without any 'arbitrary tuning'. Consider dark matter, this is extra invisible matter added to galaxies to explain why, despite their fast rotation, they do not explode because of centrifugal forces. Dark matter is added specifically to make the predictions of Newton's gravity law (or GR) fit the observed galactic rotation, but dark matter requires a lot of tuning: it is added ad hoc where needed. This means as much information goes into setting up the hypothesis as is released by its predictions, so you gain no information (dark matter is not predictive).
Now consider MiHsC. This works by reducing the inertial mass in a new way for very low accelerations, reducing the inertial outward tendency of stars at the edges of galaxies. The MiHsC prediction for the orbital velocity of stars is derived from only four parameters; the gravitational constant G, the 'visible' mass M, the speed of light (c) and the Hubble scale (Theta). All these parameters are well observed (the worst known are M which depends on the stellar mass to light ratio and the Hubble scale with an error of 9 percent) so there is no arbitrary wriggle room and yet MiHsC predicts galaxies and galaxy clusters well (see the reference below).
There should be a quantitative way to assess theories based on a ratio of the accuracy of their predictions divided by the amount of initial ad hoc tuning you have to do. With this method the completely arbitrary dark matter would score very low, MoND (Modified Newtonian Dynamics) with its single arbitrary adjustable parameter (a0) would score a bit higher, but MiHsC with no arbitrary adjustable parameters at all would have an infinite score. Of course, there are other kinds of assumption in MiHsC, for example the existence of Unruh radiation, but none of these assumptions are arbitrary ones.
McCulloch, M.E., 2012. Testing quantised inertia on galactic scales. Astrophys. Space Sci., 342, 2, 575-578. Journal / Preprint
McCulloch, M.E., 2012. Testing quantised inertia on galactic scales. Astrophys. Space Sci., 342, 2, 575-578. Journal / Preprint
3 comments:
Hi there! I know this is kinda off topic but I'd be interested in a collaboration.
My blog covers a lot of interesting and helpful posts just like yours and I feel we could greatly benefit from each other. And also, I think you'll love my recent blog post titled Be Brave! Never Be Afraid Of Speaking Out
I'm hoping to hear from you too and quickly, you've got a great blog here.
Daniel.
Yes, many times in my experience i've found people do underestimate/ignore the issues of 'fudge' factors/adjustable parameters.
It seems to me that these things allow people to quickly feel 'better', feel like they have a higher level/more complete understanding than they actually do, its a psychological thing, a lazy way to think, like assuming black or white, when the evidence only actually supports shades of grey.
(interesting recent Horizon "How you really make decisions" has something to say about these things.)
Good point. I agree dark matter is a comfortable delusion, but it is an insidious one because it is so vague it can be used to explain almost any observation. Note, I said 'almost' and therein lies the hope for a disproof.
Post a Comment