An article has just appeared in WIRED about Woodward's theory. The author Daniel Oberhaus emailed me a couple of weeks ago asking my opinion of Woodward's work and he quotes me in the article as saying "In my opinion there is no merit to Woodward's theory". See this link for the article. This quote is a 'slight' truncation of what I said :) See his questions in bold, and my answers below:
Wired: How would you sum up your feelings about Jim's theory in a sentence or two? Is he crazy or is there merit to his ideas?
In my opinion there is no merit to Woodward's theory. It shares the problem of most of modern physics that it is constrained to work within the framework of general relativity so the derivation is complex and contrived and contains many unlikely assumptions and even some arbitrarily added factors, and yet it is still orders of magnitude away from predicting the Mach effect thrust it was intended to predict! The Mach Effect experiments are interesting but we have to consider the possibility that they are vibrational artefacts.
Wired: There's clearly a lot of skepticism around Jim's Mach effect theories. If you count yourself a skeptic, what don't you buy about this theory?
There are many theoretical problems with it, see eg Rodal 2019 and in going through the derivations you see that a lot of arbitrary factors are added in. However, my main reason for disregarding it is that it does not work. It fails to predict even the lab observations it was designed to explain - its predictions of observed thrust have been shown to be a factor of one thousand times out (eg: Mahood, 1999). I note that in the papers written about it the data is rarely compared with the observations directly.
Wired: What would it take to convince you that it was correct, if anything?
To convince me it would need a simply-derived non-arbitrary formula that predicts all the Mach Effect thrust experiments and a demonstration that the thrust varies as expected given the parameters in the theory, to rule out artefacts. So pretty much the opposite of what has happened so far.
Wired: Jim's been claiming to have produced propellantless propulsion for years. Do you think these results are real, or just noise / measurement error?
I think the experimental results are more interesting than the theory, but there is a significant possibility with vibrating solid objects that artefacts can occur (as seen with the Dean drive).
Wired: If not Mach effects, what do you think is a better explanation for what could be producing this apparent thrust? Why do you feel its a better explanation?
Vibrating objects have artefacts that can appear to be thrust. If the thrust is real then it does not seem to agree with the Woodward theory anyway. I have suggested the theory of quantised inertia (McCulloch, 2007) which predicts galaxy rotation without dark matter and predicts some, not all, of the Mach effect tests (McCulloch, 2018).
References
Rodal, J.A., 2019. A Machian wave effect in conformal, scalar–tensor gravitational theory. General Relativity and Gravitation, Volume 51, Article number: 64.
Mahood, T., 1999. Propellant-less propulsion: recent experimentla results exploiting transient mass modification. AIP Conf proc. STAIF-2000. AIP, 1014-20.
McCulloch, M.E., 2007. Modelling the Pioneer anomaly as modified inertia. MNRAS, 376(1), 338-342.
McCulloch, M.E., 2018. Propellant-less propulsion from quantised inertia. J Space Exploration, Volume: 7(3).
6 comments:
Mike - it's pretty normal for a journalist to select only a small section of what they are told, and to tell people the parts that fit their preconceptions. As far as I can tell, Jim Woodward's idea actually works, and you've shown here the calculations as to how well it will work that IIRC get the magnitude of the effect about right.
Reactionless drives have quite a history, with a lot of videos on the net. Some of those appear to work (and the inventors honestly think they do and have put a lot of work in), but thrust from the vibrating bits is from a different frictional effect in one direction than the other - it's actually reaction but not correctly measured. Given the number of such failures, it would be easy to lump in Jim Woodward's idea in there, too. After all, conservation of momentum is very well proven and is an axiom.
Momentum is normally conserved because the fields that transfer the force between objects are constant. Thus force multiplied by time is equal and opposite in an interaction. This situation does not however apply when we use a varying field such as a wave, because the wave has a propagation velocity (normally c) and so the phase of the force varies with distance. Force times time may not be equal and opposite in this case, but until you get to very high frequencies the wavelength is generally large compared to the device and any effect will be unmeasurably small. Given that we "know" that momentum is conserved in all cases, any deviation would be regarded as experimental error anyway.
Maybe the central question of QI is how you create a barrier such that all Unruh waves must have a node there. Personally, I suspect that the Unruh waves may be mis-identified, and are in fact the Schrödinger waves of the matter itself (and thus have infinite "propagation speed" and can convey information across the Hubble distance instantaneously). Since there seems to be some sort of shielding as a result of velocity, and spinning objects, maybe this change of perspective might help in figuring out a better way to produce those nodes.
"Wired" is an anagram of weird, which is maybe a good description of the way the universe works at the very basic level. Not quite as simple as Newton thought it was.
I'm a big fan of QI but I also think Woodward's team did reproduce key features of the theoretical predictions such as dependence of the voltage to the forth power. The claims of spurious vibrational effects are all too easy to make and the most recent noise made was by an amateur experimenter with a garage setup made of 3d printed plastic parts. But it doesn't take much to do damage. I'm skeptical just as I would be if people just discounted the small thrusts possibly seen on QI devices as "probably just thermal effects". I see no fundamental objections to suppose that the Woodward effect and QI both could be true. There are even other possibilities as well such as physicist Jack Sarfatti's recent work relating to sub-light speed Alcubierre drives at low energy.
Simon: It would be fantastically elegant if the Unruh waves were matter waves. I have not found a way to do that, yet. For example the matter wavelength is h/mv whereas the Unruh wavelength is 8c^2/a. One depends on speed (a dubious concept anyway!), the other on acceleration.
Robert: Thank you for your comment. When I looked at Woodward's theory I relied mostly on a paper by Masood (1999) since that was the only one that contained enough information that I could try QI out on the results. As far as I could tell, and I may be wrong, Woodward's theory predicted a force 1000 times smaller than the observed thrust. I discussed this in my paper: Propellant-less propulsion from quantised inertia, in the Journal of Space Exploration.
Mike - AFAIK, Schrödinger waves are a superposition of wavelengths from a minimum wavelength to infinity, such that the composite wave is a packet in 3 dimensions. If instead the range of waves available to build the wave was restricted such that only waves with nodes at the Hubble radius (or other horizon) were allowed, there would be little visible difference to the resultant wavepacket. However, moving the horizon would make an instantaneous difference to the wavepacket, since the magnitude of the wave translates to the probability of finding the particle at any point and that probability will not be zero except at the Hubble radius. Thus information about the horizon in effect travels instantaneously.
With h/mv you're maybe thinking along the lines of the Compton wavelength, where the equivalent mass is treated as being a photon of that energy. Not quite the same thing. Instead, I'm suggesting that the Schrödinger wavefunction actually is not just a wave in a (mathematical and non-physical) probability function, but instead is the actual matter density at that point. If it is the actual matter, and those waves can overlap (as they must do) and add to the total matter density at any point, and if we speculate that the greater the density of the matter waves the slower time runs, then that gives a reason for gravity since time runs slower where the matter-waves overlap. The more the waves overlap, the slower time runs, and thus the potential energy in that volume reduces the closer the particles are to each other. This gives rise to an attractive force we identify as gravity. Thus gravity would not produce a slowing of time, but instead gravity would be caused by a slowing of time. Given the quantised nature of the available wavelengths, that would also quantise the gravitational force.
Note I'm proposing these ideas as seeds rather than fully-formed thinking, so they can be built on if useful and discarded if they aren't useful. Whereas a photon can carry momentum, I'm not at all sure that a continuous wave (Unruh wave) can. There is however evidence that we can send data along a coax faster than light (experimentally 5c to 8c) using an unterminated line, at the phase velocity rather than the group velocity, and this may explain the anomaly (to my mind, at least) where something like a bazooka balun can present a very high impedance to a signal before that signal has actually reached the point of high impedance. As such, it's conceivable that an EM wave such as the Unruh wave can indeed transfer information instantaneously, and is not limited to c.
As such, I'm chucking ideas at the wall and seeing which ones stick, in the hope that a different approach may trigger a better idea from someone else.
Lately, Woodward discovered his technique was dampening out the results and he now gets much bigger results. So big Woodward himself is skeptical. Time will tell if the results are all artifacts and Woodward himself is aware there still might be vibrational artifacts in the data but that if so, it would only be a component in his view. I do discount the vibrational claims by recent critics as the whole story. That narrative requires too many highly skilled experimenters to be wrong on numerous different experiments which is doubtful. And they don't explain the forth power scaling of the data with voltage.
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