I am giving a seminar tomorrow to the Plymouth Astronomical Society, so here is a summary of the talk which is humbly titled: "How to predict the impossible". The impossible in this case is of course the emdrive, a truncated cone-shaped microwave oven that seems to move very, very slightly towards its narrow end as the microwaves resonate within it. This is causing a lot of incredulity in physics, since humanity has never before encountered a system that is able to move itself in one direction without apparently expelling reaction mass in the other direction. The usual rule is called the conservation of momentum and is a very well tested. The emdrive anomaly was first discovered by Roger Shawyer and has recently been reproduced by others, including NASA's Eagleworks Lab.
For many years I have been proposing a theory called quantised inertia, that states that the property of inertia (that which makes it hard to stop walking into lamp-posts) is caused by relativistic horizons damping the quantum vacuum. When you accelerate in one direction two things happen 1) the waves of the quantum vacuum that you see get shorter (Unruh radiation) and 2) a horizon (like a black hole horizon) appears in the opposite direction that damps those waves. Quantised inertia states that the resulting asymmetry in the quantum vacuum pulls you back against the initial acceleration and so it predicts inertia for the first time, but also predicts a new loss of inertia when accelerations are so low that the Unruh waves get damped symmetrically by the cosmic horizon, so it also predicts galaxy rotation, and its change with time, perfectly without dark matter.
How about the impossible emdrive then? Well, it is an asymmetrical cavity, so the idea is that in the narrow end the microwave photons lose some inertia because the Unruh waves don't fit so well (just like galactic edge stars lose inertia because the Unruh waves they see don't fit well inside the cosmic horizon, and so feel less centrifugal force). As a result the emdrive photons gain inertia every time they shuttle towards the wide end, and to conserve momentum the cavity has to move towards its narrow end. Quantised inertia predicts the emdrive thrust data quite well, as I showed in a previous paper. Further, quantised inertia predicts that if you happen to put a dielectric in the wide end, this will shorten the Unruh waves, so more will fit and the gain of inertia from the narrow to the wide end will be enhanced and the cavity will accelerate more. Considering the dielectrics too, quantised inertia predicts the emdrive thrusts extremely well. The Figure below shows the observed thrust on the y axis and the thrusts predicted by quantised inertia on the x-axis, both without considering the dielectrics (white squares) and considering the dielectrics (black diamonds).
The diagonal line marks perfect theory-data agreement. The effect of the dielectrics can be seen most clearly for the tests marked 'NASA2016' (the four white squares, lower centre) where quantised inertia over-predicted the thrusts (the values ideally should be on the diagonal line) until I noticed that NASA put dielectrics in the narrow end of the cavity, thus inadvertently reducing the thrust. When this is considered in quantised inertia, the white squares shift left to become the black diamonds, close to the diagonal line. It can also be seen for Shawyer1, who put a dielectric in the wide end, thus boosting the thrust (top right). This dielectric dependence is a good confirmation of quantised inertia.
Applications of this are to be found in any form of terrestrial of space transport, and one advantage of the explanation from quantised inertia is that it suggests that dielectrics can be used to enhance the effect, which has been too small to be useful as yet. My latest paper on this is just about to appear in EPL (see the reference below).
Applications of this are to be found in any form of terrestrial of space transport, and one advantage of the explanation from quantised inertia is that it suggests that dielectrics can be used to enhance the effect, which has been too small to be useful as yet. My latest paper on this is just about to appear in EPL (see the reference below).
To change the subject for a bit, it would be fascinating to go to another star in a human lifetime, but for that you need to travel close to the speed of light so that relativistic time dilation gives you an Einsteinian version of suspended animation. For example, if you accelerate at 9.8 m/s^2 for one year, travel at 90% the speed of light (c) for 10 years and then decelerate for one year at 9.8 m/s^2 you could make the 25 light-year trip to Gliese 667 in 12 years (the duration for those on the ship). Unfortunately, although theoretically possible, engineering gets in the way. To get a habitable normal spaceship to 90% of c you would need more energy than can be produced by our civilisation, or as much fuel as a small planet. The emdrive, though, as quantised inertia suggests, uses 'nothing' as its fuel and nothing is readily available everywhere in space (of course, a power source would need to be included).
References
McCulloch, M.E., 2017. Testing quantised inertia on emdrives with dielectrics. EPL.. Preprint
25 comments:
Hi Mike
If you want to travel to the stars and have a continuous source of thrust, then accelerate the whole way - with a reversal of thrust direction at the mid-point, of course. Trip-time at 1 gee, measured by the ship's clocks, would be 6.35 years, with a maximum speed of 0.9971 c. Maximum Lorentz gamma factor would be 13.2. Of course it might not be feasible to fly so close to lightspeed in the interstellar medium.
How analogous is QI/horizon mechanics explaining how the EM drive/RF cavity thrusters work, as to how it would explain the operation of a Mach effect thruster?
Could QI be derived from Mach's principle?
Seems the only difference is manipulation of radiation vs manipulation of a field.
Hi Dr Mike,
Before I go off topic, another question:
What is the predicted thrust/efficiency of an optimised cavity with a dielectric?
(Besides Shawyer 2, a lot of the dielectric tests tend to show low efficiency, according to the EMDrive Wiki).
If the drives can be brought up to 5% efficiency, these new technologies are viable with huge thrusts available. I envisage small modular nuclear reactors to be utilised unless we have a breakthrough in harnessing the quantum foam and so on. The smallest US Navy submarines used for oceanographic mapping apparently had 5 MW reactors, being the size "of a dustbin".
Dr Mike, feel free to delete this as you wish - but I have some practical questions. If you know of any resources you could point me to, this would be greatly appreciated.
Has any group stated what is needed for true interstellar travel?
I would guess you'd need:
1. Warp drive. For FTL travel and to create a warp bubble/force field to prevent collisions in space.
2. EM drive. For transit to the moon, to get off the planet etc. I'm not sure mucking about with space-time is particularly nice for the neighbours. I'm thinking of something like earthquake-style damage.
3. An anti-gravity drive of "some kind" relying on the Podkletnov effect. The reason for this is to minimise "static" "friction", to make take off and landing easier, but to ensure the craft didn't fall vulnerable to black holes or large stars or planets the craft may have ventured too near to.
A few other ideas:
4. Without breakthrough energy generation, nuclear power. Fission works. The challenge would be making the cores, deflectors, absorption and generation system lightweight, compact and solid state. A lack of moving parts may minimise maintenance. Also given the time of some travels, long lasting fuel sources and high enough output. Quite a challenge, but it seems like a maths/engineering problem.
5. Some kind of very strong alloy (gold-titanium) but perhaps with eutectic properties for durability.
6. On board gravity. Other life support systems like shielding against radiation and high energy particles. Rebreather systems and adequate food storage, medical supplies and sanitation - also entertainment. We don't want to flip out, out there.
7. Very accurate astronomical maps and an excellent navigation computer.
8. Possibly a warp system to "suck in" particles from stars for combustion. So you'd never run out of fuel for fusion reactors. Beyond the stellar cloud, particles might be hard to come by.
9. On the idea of shaped microstructures harvesting the quantum foam - a series of spiral coils with overlapping, curved (?) fine metal (iron) plates coated in gold, close enough for the desired effect. Once you got moving, possibly you'd be interacting with the Dirac Sea.
10. Possibly several thrusters and power sources. This would help with manoeuvrability.
Hi again Mike,
One thing we should discuss is the power supply needs for the 1 gee space-craft and the EM-Drive parameters needed for that performance. Say we have a 1,000 ton spaceship and we accelerate at 1 gee. Thus 10 MN thrust is required. At Eagleworks' observed performance of 1.2 millinewtons per kilowatt, the power to get 10 MN thrust is 8.3 TW, which is probably unrealistic for a 1,000 ton ship to supply. We might be able to do it with a laser bank beaming at a high-efficiency collector, but it's still herculean by modern standards (we're just starting to make sustained 100 kW lasers.) It's still much better than the laser power needed for a purely photonic drive, some 3 petawatts, but it's a long way from our state of the art.
Of course the performance increases with the Q-factor. Tune the cavity and make it superconducting. If we take the NASA EM-Drives and pump the Q factor to ~30 million, then about 2 GW power is needed for the sustained 1 gee thrust. A fast-spectrum reactor with a thermal output of ~ 6 GW and ~35 % thermal conversion efficiency would be a first pass design to supply the power. Assuming ~100% burn-up the fuel used over 20 years masses 4.2 tons. If the reactor mass was limited to ~200 tons, then it'd need to supply power at 10 kWe/kg of reactor mass, which is very high performance. A gas-core or magnetic collimator fission-fragment reactor might be up to the job, but both are somewhat futuristic.
Fusion reactors are presently *hoped* by propulsion engineers to be able to supply power in the 100 kWe to 1 MWe range, though no working fusion power-reactor has yet been demonstrated. As the joke goes, fusion has been "just 20 years away" for the past 60 years and always will be...
I wonder just how high a superconducting EM-Drive's Q-value can go?
you don't need a 1g thruster to revolutionize space flight, you only need 1g or greater to launch from the surface of the earth.
Once you are in orbit, even a .1g or .01g thruster that can be run continuously will revolutionize travel, and the travel time difference between .01g and 1g is trivial compared to .01g and current approaches.
David Lang
Superthruster rumors beating theories
Zephir,
As the responses to that claim have said, let's *see* the results.
Hey Mike,
How did the talk go?
qraal: Very well, thanks for asking. The audience asked some good questions. Some one did mention Sagan's comment that 'extraordinary claims require extraordinary evidence'. In my opinion this comment is always pointed at the wrong theory. Just look at dark matter, which proposes new matter and needs new physics to go with it, and it is loved by the mainstream with no evidence at all. Or string theory, that does not even make predictions. In contrast quantised inertia has a lot of direct evidence in that it can predict all galaxy rotations and other things directly and without any tuning, and yet Sagan's comment is thrown in my direction! So I think this criticism should be applied to the mainstream instead (I did not say that in reply to the comment on Friday, but this is what I would like to have said!).
Joesixpack: Quantised inertia (QI) is not like the Mach effect which is based on general relativity alone and with no new physics. Mach Effect is therefore a hypothesis built on a basis that IMO has been shown (by galaxy rotation) to be incomplete. Also Mach effect cannot explain any of the more rigorously measured anomalies that QI can. Although I don't buy his hypothesis (I find his presentations of it to be confusing or obfuscatory) I think Woodward's experiments are interesting and may be explained by QI, but I have not tried it yet since it is easier to know the acceleration of stars in a galaxy than that of electrons in a piezo-electric.
Zephir: Thanks for the link, interesting, but I do agree with qraal here that I'd like to see more detail. We have to be careful to focus on results that have been peer-reviewed (not always possible) or at least a complete account.
@Mike, while I agree that QI is simpler than dark matter, the EM Drive is definitely an "extraordinary claim". The recent NASA testing helped, but this is actually a relatively simple (but not especially cheap) thing to test, it just needs to be put in orbit with sufficient power to run it for a while, the difference in the craft's orbit should be pretty easy to measure, and if it's run long enough, any claims that it's leaking something should be able to be debunked.
I wonder if something could be put together to ride on top of one of the Space-X highly experimental launches (such as the first falcon heavy launch), it doesn't need to be a sophisticated/expensive satellite, just enough solar panel to power the em drive, something to keep the solar panels pointed at the sun, and some sort of beacon to track it (and better if the launch is beyond earth orbit)
unfortunately, I don't think you can do enough power in a cube-sat to make it worthwhile.
David Lang
David: Some tests in space have been planned, and may even have been done:
https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster#Tests_in_space
and Paul Kocyla from Germany has been trying to get crowdfunding:
https://www.gofundme.com/25tmmes
@Mije+@David
And not to forgot that attempt too:
https://hackaday.io/project/5596-emdrivesatellite
Hi Mike
I think it's unfair to characterise Dark Matter as an 'extraordinary claim' without evidence, since the evidence is exactly the same as you seek to explain with Horizon Mechanics. But that would mean they're *both* on equal footing as 'explanations' of the same data. However HM actually explains the Galaxy rotation curves etc. while DM says "well if you assume particle X (and Y and Z and...), then we can explain the curves etc." Parsimony seems to prefer HM over DM.
But how do you explain the gravitational lensing results that appear to show bridges of Dark Matter? My guess would be sufficient Intergalactic Plasma to form the bridge and HM to magnify its gravitational effects, but I'd much rather see your more able analysis than my hand-waving. I'm afraid I'm a bit more obfuscatory too when I'm trying to plug gaps.
@Czeko:
The link you provided is Paul Kocyla's project, whom Mike cited in his message just above yours.
Hi Mike,
A question for you - i'm sure you've answered this (not directly) elsewhere, so i guess i'm being lazy. I'm a real believer in QI, I really love the beautiful simplicity of it (compared to DM on MOND for instance), BUT... I guess my sources are biased. Now for the question: What are the outstanding problems with QI (as a theory)? Does it make any predictions that we don't observe? I often see your blog posts basically comparing the QI prediction to the observation, where are the counter blog posts to yours showing data that doesn't match predictions? Put another way, what are the valid criticisms of QI? My goal here is to be a bit more balanced in my thoughts about this.
What good reasons are there for any well reasoning person to deny the validity of QI?
All the best,
James
P.S. You should record your talks/seminars and put them online somewhere - some geek might watch/listen to them....
James: Good question. I should do a blog directly on this, but I can say a few things quickly.
1. Quantised inertia implies that inertial mass is in some sense non-local as an accelerating body is apparently in touch with the cosmic horizon. This is not a serious objection since EPR implies non-locality anyway, but it does means some fundamentals with have to change: probably our understanding of time (I have a paper in the works on that).
2. QI strictly violates the equivalence principle, but as I have said on many occasions, not in a way that could be detected in torsion balance experiments.
3. The way I have derived the theory is an approximation. The Unruh field will not drop of quite linearly, since some wavelengths will resonate with horizons and some won't, so it will be a more stepped process: a refinement is necessary that will produce more complex (slight) variations.
4. From a standard physics point of view it looks like energy is coming in from nowhere,but in QI energy comes in from a new source: the destruction of information.
5. Unruh radiation, which I have been depending on, may or may not have been seen. There is a paper by Smolyaninov (2008, Physics Letters A 372, 7043-7045) that suggests it has been seen as light emitted from plasmons propagating around gold nanotips.
Just a (mostly pedantic) clarification on the closing comment. "Fuel" isn't the word you're looking for, but propellant[-mass]. Fuel is mass that contains the energy for propulsion. Propellant is the mass actually imparted with that energy and ejected to incur a change of momentum.
In chemical-fueled rockets, the kerosene or hydrogen, and NOX or LOX, constitute both the fuel and the propellant. Energy is liberated by combining hydrocarbons and oxygen, and the products of that chemical reaction are ejected as the propellant in one-go. Nice a clean.
But in something like an ion thruster, the propellant is the Xenon or Argon that's accelerated by an ion-accelerator. The 'fuel' would be (one day) the Thorium, Uranium, or Plutonium that's running the nuclear reactor on board. This part can get fun, in that Xenon, among other things, is a significant fission product, so some of the used-up fuel could be re-purposed as propellant as a 2nd order thing. But I digress.
This would be the same set-up with the EM drive, if it ultimately does pan out. You'd require no propellant mass, but you would still have to bring along quite a significant amount of fuel. The exponential tyranny of the Rocket equation won't be denied. We'll still need to bring extra uranium to propel the extra uranium we've brought, though with the energy-density of nuclear power, we'd get to knock off 3 to 6 magnitudes on the exponent. I suppose anti-matter would be the next, and probably final logical step to get another several magnitudes off of the initial value. But I won't hold my breath on that for my lifetime.
Mike,
Ars Technica has an article up about doing away with dark matter. And the cosmological horizon being used to derive gravity. I thought of you immediately.
https://arstechnica.com/features/2017/05/emergent-gravity-and-dark-matter-explained-by-excited-universe/
It is held that "nothing leaves" except notably heat radiation. This could be irrelevant, but if these "tuned cavities" somehow produced very low frequency electromagnetic radiation wouldn't that be able to escape due to high penetration depth? (and subsequently generate some thrust from radiation pressure if directionally "expelled"). Could such sub-harmonics from microwaves be generated by emdrive-devices?
...in relation to penetration depth copper should have the upper hand compared to steel... But this was just a bit of speculation.
I guess it is not clear to me how an emdrive will get a hold on "the edge".
Well, crapola is what it is. Em-drive is soon forgotten, but of course Mike can find some other fantastic coocoo from the edge and adjust his fairytale theories for that.
Pathetic trolling. The peer reviewed paper from JPL has not been refuted yet.
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