Launching with physics instead of chemistry.

I've just seen the attempted launch of the Falcon 9 rocket (their next try will be on Tuesday) and I think SpaceX is the most exciting thing to come out of the USA since the Apollo program. The UK's SKYLON project looks potentially bold too and I wish these, the consistent Russian manned space program, the growing new Chinese program, and other space programs the best of luck, but seeing launches like this I always think there must be a way to launch to space without chemistry, and maybe there is using MiHsC:

If inertia is due to Unruh radiation then it should be possible to modify the inertia of objects by interfering with, or enhancing, the Unruh radiation they see. Then, as their inertia changes, the conservation of momentum should cause them to move. I proposed one test of this at the end of this paper (published in EPL, 90, 29001, 2010, see the section just before the Conclusions):

Since then I have tested MiHsC on some experiments done by Tajmar (the Tajmar effect), by assuming (as above) that the sudden acceleration of an object (a ring in this case) near to a gyroscope changes the Unruh waves it sees, and therefore its inertia, causing it to move to conserve momentum. MiHsC predicted the anomalous observations very well: see this paper (published in EPL, 95, 39002, 2011). I discuss the idea of launching using inertia here (unfortunately, this abstract has been deleted, email me if you want a copy).

Of course, getting funding to test this is going to be difficult, but I think it would be worth it, since it could provide a new method of launching without dangerous high explosives.

In Between the Models.

Yesterday I attended a talk here at UoP by an academic from Swansea. He was a nice chap who gave a brilliant talk on a subject he passionately believes in: string theory and the AdS/CFT (Anti-deSitter Space/Conformal Field Theory) duality. So while being tremendously impressed by him, I was unimpressed by string theory.

The summary is that a unbelievably complex string theory in 11 dimensions looks rather like a 4 dimensional Conformal Field Theory without gravity. At the end of his talk I asked him whether "it might be just a meaningless coincidence that 11-d string theory looks a bit like 4-d CFT?' and I told him that an experimental test was needed somewhere. He said that when you actually do the calculation the similarity is so miraculous, even from such a complicated theory, that it must be right. Not necessarily! Maybe it is just coincidentally how the maths works out in the collapse from 11 dimensions to 4. Maybe theorists have now played around with so many 11-d string models that they have finally found one that by accident looks like the 4-d CFT model? Ptolemy's epicycles were very complex and reproduced the observed behaviour, but were wrong. To do physics, string theorists have to suggest an experimental test whose behaviour would be different depending on whether string theory is true or not, otherwise it is mathematics, not physics.

Mathematics is essential for setting up predictive models, but is just a human invention, a derived thing, and I don't believe you can get paradigm shifts in physical theory by just "mixing up" old mathematical models. In the same way, there are probably an infinite number of concepts whose description lies outside the words we have, and you'll never get to them using existing words. Something non-verbal from outside is needed as a initial guide: from observation & intuition and then words (or maths) can be invented to describe them.

Unfortunately, the uber-mathematical approach is the fashion in theoretical physics right now, and it always reminds me of a quote about the death of ancient Greek science: "speculation went way beyond the testable, and into metaphysics" (words or maths with no input from nature) , so to avoid this I always try to think about anomalous observations, which is very difficult, messy and even misleading sometimes, but at least makes me feel I am doing something real and new.

The Metal Box Problem.

In spring last year (6th April) I was asked to visit St Andrew's Physics and Astronomy Department to talk about MiHsC. Well, the reality is I managed to get myself invited because I had met one of them, Dr HongSheng Zhao, at an Alternative Gravities conference in 2006.

Prof Keith Horne kindly organised my visit, and it was a fruitful in some ways, although nothing came of it regarding collaboration. At lunch, before I was to give my talk, one incisive chap, whose name I forget, rattled me by asking me whether the Unruh waves I use to generate inertia could penetrate a metal box (Faraday box). This is something I thought about years ago and I eventually decided that MiHsC-inertia would be unaffected by a metal box, since the Unruh waves for the accelerations we see on Earth are 10^16 metres long and should be able to penetrate (submarines can pick up very long EM waves deep under the conducting sea). The consensus round the table was that the EM component that I was focusing on could not penetrate, but other components of the Unruh radiation could.

Later at coffee, one chap (C.Hooley) suggested that what might be possible is that the sub-selection of Unruh waves by the Hubble scale Casimir effect, that I use in MiHsC, might be already tuned into the local space (like a curvature?) and so wouldn't have to get into the metal box and this would also solve the communication with the cosmic boundary problem. I also wonder if the waves might actually get in through the time dimension rather than the spatial (the same thing?). If only I had access to these kind of stimulating conversations every day! Anyway, disregarding for the moment how nature actually does it, the Hubble scale Casimir effect does seem to work for the specific experiments I've looked at so far. Keith asked whether I'd tried to get gravity from MiHsC too, using a sheltering method. I have now tried this and it produced the wrong kind of dependences, but another method is proving more successful..

When I left Keith said that I'd 'Provided some entertainment and given them something to think about'. I wish I had more opportunity to interact with other physicists. I value tricky questions: in my experience progress comes after crises of doubt.

http://www.st-andrews.ac.uk/physics/index.php

Criticism of the thermal model of the Pioneer anomaly

I have just read through the papers by Turyshev et al. (arxiv: 1204.2507, 1107.2886) in which they argue that the Pioneer anomaly is due to thermal radiation from the RTGs bouncing anisotropically off the spacecraft antenna. First of all, well done to them and the Planetary society for the Pioneer data rescue: the data is the important thing, and I appreciate a lot of work has gone into the finite element modelling. However, I have some criticisms of their thermal explanation of the anomaly:

1) An identical anomaly to the Pioneers' was also found by Anderson et al. in data from the Solar Ulysses probe, and, less conclusively, in Galileo probe data. See: http://arxiv.org/abs/gr-qc/9808081. These spacecraft were very different, and it's unlikely that thermal effects would cause the same acceleration.

2) As they themselves say in their 2011 paper (page 4) the Pioneer data is still too noisy to prove whether there is a decay with time in the anomaly or not, and a thermal explanation can't be supported without a proven decay.

3) The half life of the decay with time that best fits their thermal model is 28.8 or 36.9 years whereas the half life of the Plutonium on board is 87 years.

4) Their predicted anomaly is at its largest in the inner Solar system where there was no Pioneer anomaly. They have got around this by proposing there was an exactly cancelling push because the Sunward side of the craft was warmer due to sunlight (Turyshev kindly emailed me to point this out), but looking at their Fig. 2 from their latter paper this does not exactly cancel the onboard thermal effects, so I guess they had to adjust the momentum flux from photons close to the Sun that was originally assumed by Anderson et al.?

5) Anderson et al. (2002) (arXiv:gr-qc/0104064, p32-33) said that, since most of the heat from the RTGs was radiated from fins whose flat surfaces were not pointing at the antenna, only their narrow edges, only 4W of power, could have hit the antenna, leading to a maximum acceleration of only 0.55*10^-10 m/s^2.

6) Since the power radiation Q is proportional to the fourth power of temperature, I'd like to see the temperature errors they get, since any errors from this source would be hugely magnified.

More generally, I always find it difficult to accept a paper when a very complex and unrevealed process (over 3000 finite elements, not fully detailed in the paper) and with fitting parameters, is used to get to a previously known answer, and no experiment is suggested that might unambiguously test it against rivals. I dislike dark matter for similar reasons. I'd like to see them present a simplified order-of-magnitude calculation so others can reproduce what they have done on paper.

Here's my explanation for the Pioneer anomaly using MiHsC, published in MNRAS: preprint.