I've written a few blogs of late, showing how quantised inertia (MiHsC) predicts galaxy rotation and other things perfectly without adjustment, but to avoid sounding like a advert I also want to talk about the new things I am puzzling over. So this blog entry will be a bit messier, but perhaps more fruitful.

I've mentioned before that the gravitational constant (big G) is in trouble. Well, it still is. I recently read an interesting paper on this by Norbert Klein (see references) who analysed two of the recent experiments to measure big G in light of the galaxy rotation problem. The experiments typically measure G using a development of the Cavendish experiment. For example Quinn and Speake (2014) suspended four 1.2kg masses arranged in a circle radius 120mm (see the 4 small balls in the diagram below) from a fibre (the vertical line) and then put four much larger masses (11 kg) on a 214 mm radius circle around them, and then rotated this outer circle by 18.9 degrees so that the tiny gravitational force between the four pairs of masses twists the inner arrangement, so that they can work out from the twist what the force is. Since they know the masses M and m, the force F and the distance (r) very well they can work out G from Newton's gravity law: F=GMm/r^2.

I've mentioned before that the gravitational constant (big G) is in trouble. Well, it still is. I recently read an interesting paper on this by Norbert Klein (see references) who analysed two of the recent experiments to measure big G in light of the galaxy rotation problem. The experiments typically measure G using a development of the Cavendish experiment. For example Quinn and Speake (2014) suspended four 1.2kg masses arranged in a circle radius 120mm (see the 4 small balls in the diagram below) from a fibre (the vertical line) and then put four much larger masses (11 kg) on a 214 mm radius circle around them, and then rotated this outer circle by 18.9 degrees so that the tiny gravitational force between the four pairs of masses twists the inner arrangement, so that they can work out from the twist what the force is. Since they know the masses M and m, the force F and the distance (r) very well they can work out G from Newton's gravity law: F=GMm/r^2.

The trouble is that the two different values of G they found disagree by more than the uncertainty in the experiments! Which they just can't do, unless something 'unknown' is going on. Schlamminger measured G=6.674252x10^-11 m^3kg^-1s^-2 and Quinn and Speake found G=6.67545x10^-11 m^3kg^-1s^-2. The observation that got me excited was that Norbert Klein, in his paper, points out that in the Schlamminger experiment (the low G value) the gravitational acceleration between the two balls (if they'd be free to move) was relatively high, but in Quinn and Speake's experiment (the high G value) it was very low.

This agrees with quantised inertia since a low acceleration should mean the small ball has lower inertial mass and so is more sensitive to the large ball, so it should 'appear' that G is bigger, as indeed Quinn and Speake found. I have done a rough calculation assuming the mutual acceleration is four times the gravitational acceleration between each pair of balls (there are four pairs), and quantised inertia predicts that the apparent change in G divided by G (dG/G) should be 11.3x10^-4 whereas Quinn and Speake measured a change from the standard value of G of dG/G=3x10^-4.

The prediction is a factor of 3.8 out, but there are large uncertainties in the calculation. For example, what is the correct acceleration to plug into MiHsC/QI? Is it, as I have assumed, the along-inner-circle component of the acceleration that the small mass would have towards the bigger one, times four? Does the rest of the environment contribute? How about the curve of the ball around its circle as it moves? That is an acceleration too. Also, what is the 'raw' value of G, that MiHsC/QI predicts should only be seen at high accelerations? This affects dG. It's something interesting to think about anyway.

My family must think I'm training for a boxing match since I can often be found these days walking round the house holding my fists up to represent two balls and mumbling to myself.. Saying that, maybe I should learn to box: given some of the online responses to MiHsC/QI, if I ever attend another conference, such a skill might be needed!

References

Quinn, T., C. Speake et al., 2013. Phys. Rev. Lett., 101102. Link

Schlamminger, S., 2014. Phil. Trans. Roy. Soc., 372, 20140027. Link

Klein, N., 2016. Are gravitational constant measurement discrepancies linked to galaxy rotation curves? https://arxiv.org/abs/1610.09181

## 7 comments:

Here's an earlier paper by Klein that's longer:

https://arxiv.org/abs/1504.07622

Also, here's a paper with more detail on the Quinn et al. experiment:

http://royalsocietypublishing.org/content/roypta/372/2026/20140032.full.pdf

Thanks Tom. You were the one who pointed out Klein's paper to me, in a comment on a previous blog entry. I am now in email contact with Klein..

a thought I just had. given that you have now found a way to derive gravity from QI, have you looked at what happens if the Hubble value is very small?

I just had a TV show talk through the big bang and how (per their explination) the laws of physics had to change several times during the process to explain what happened.

I was wondering if QI with very small scales possibly paints a much cleaner picture of things.

Indeed, MiHsC predicts that when the Hubble volume was small, the minimum acceleration was large, so it predicts inflation, which solves the flatness problem. Actually, cosmologically, MiHsC looks a bit like Hoyle's steady state theory, which was discredited for not predicting the cosmic microwave background, except that MiHsC does predict a CMB. More details here: http://www.mdpi.com/2075-4434/2/1/81

Mainstream cosmologists should try MiHsC out in their models.

Gravity constant is time dependent due to fluctuations in dark matter density https://www.reddit.com/r/Physics_AWT/comments/33e1as/why_do_measurements_of_the_gravitational_constant

Could MiHsC somehow account into it?

I read your book and blog posts and have found them very interesting. Here is a question for not only your own model but that of other theories where gravity is a "emergence" for another force. Is your model able to predict gravitational waves? Since they have been observed how Unruth Radiation account for them?

dhammett2004: Here is the blog I wrote back in February 2016 on the LIGO data:

http://physicsfromtheedge.blogspot.co.uk/2016/02/comment-on-ligo-grav-waves.html

They assumed c=constant. With MiHsC it may not be quite so simple.

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