Woodward's effect

[grondilu]

So, as suggested here, I open this thread about Woodward's effect.

I try to understand his paper called Recent Results of an Investigation of Mach Effect Thrusters, and there are already some details I don't get in the first equations.

Here is a mathbin:  http://mathbin.net/154127

I'm not sure this 3/2 factor really matters or what but already it nags me.  Funny thing is that if the test particle was "outside" of the universe, then sure, one could use the gauss theorem or stuff like that and the universe would provide a potentiel just as if it was ponctual.  But if I assume the test particle is in the middle of a universe, then there is this 3/2 factor.  That's weird.

[D_Dom]

I know the previous thread runs long. Wish I understood more of the theory. Here is a link to some of Dr Woodwards research.
 
http://physics.fullerton.edu/component/zoo/item/dr-james-f-woodward







edited to update the link

[grondilu]

As far as I'm concerned, I'm not troubled by the missing 3/2 factor any more.  It doesn't matter as long as in the end we end up with the potential as it would be if it was static.  That's what Woodward use instead of GM/R anyway so that's fine.

But in the following step in the same doc, I don't get the mathematical path from the fourth-divergence of the force to what he describes as the wave equation for the scalar potential.  In other words, I don't get how he goes from equation (5) to equation (6).  It seems to be a classical calculation in electromagnetism so he's very quick about that, but I don't have this much background.

Anyone would be welcome to explain.

[GeeGee]

Anyone well-versed in physics care to comment on this criticism?

"If you break conservation of momentum, you break the 1st law. If you manage to magically nonlocally transfer momentum with the rest of the universe that happens to be in your exact reference frame you break the second law (and quite a lot that we assume about how the universe works with respect to nonlocal interaction.) If you have a drive that reacts with the average reference frame of the rest of the universe and has an 'efficiency' that is relative to the difference in that reference frame, you have a preferred reference frame and break the principle of relativity.
If this experiment isn't in error (and it almost certainly is) then one of those has to go."

I've heard this claim quite often -- that mach effects break the laws of thermodynamics, but this is the first I've heard that it violates the principle of relativity. However, I have a hard time believing Dr. Woodward would waste his time on something that so obviously breaks fundamental laws of physics, or that this massive implication wouldn't have been caught in the peer-review process, or by anyone over the last decade.

[ScottL]

Chrismb did a write up on how it may not violate any of the laws here:
http://talk-polywell.org/bb/viewtopic.php?t=4228

In which he goes through the math, however; Chris is not a proponent of the purposed effect, but merely stating that the possibility exists based on the maths.

[LegendCJS]

... caught in the peer-review process...

First, you can get almost anything published, just look at the journal of Cosmology.  With the internet you can distribute anything as well.

Reporting on experiments saying "Here is what we built, here is what we did, and these are the signals we got" is also pretty easy to publish because its is presumably true, and they have themselves "covered" because it is stated in that way.

However, you do not see publications on the topic in reputable journals because the peer review process is doing its job.

And you have to understand something about academia/science: its history is littered with revolutionary concepts that violated previously established ideas, and whose advancement were resisted at first.  That is why tenure exists, and that is why scientists don't mind working on anything, and you never know how it will pay off.

Even if it is all bunk and all the evidence so far is the effect of some obscure kind of measurement or experimental error, it is still worthwhile to continue Woodward's search for ever more sensitive tests and instruments and procedures to put the particular kind of error to bed, and possibly provide a valuable instrumentation advance to science. 

Think of the FTL neutrino episode, it was bunk, but you can be sure every experimental physicists everywhere is making sure that their fiber optic cables are properly secured into their instruments now, and that leads to better science results and makes scientists more careful in the future and these are good things.

In Woodward's case the marginal cost/money required for his experiments and hardware seems (to me at a distance) to be insignificant compared to his and his assistant's salaries, so there really is no strong argument to be made that he is wasting resources.  He is a history professor after all, what else would he do if we wasn't fussing with vacuum chambers and coils of wire and signal generators and oscilloscopes and force balances etc.

[antiquark]

I looked around a bit for a more "intuitive" explanation as to why it's like a perpetual motion machine. Found one on wikipedia!

http://en.wikipedia.org/wiki/Woodward_effect

If allowed to accelerate horizontally on a frictionless plane, the kinetic energy would grow as the square of the elapsed time, while the input energy grows linearly with time. Thus, after a characteristic time T, "free" energy would appear to be continuously available in ever-increasing amounts

Wiki says Woodward doesn't deny this, but says that the energy comes from the rest of the universe. Sounds like perpetual motion to me!

[strangequark]

I looked around a bit for a more "intuitive" explanation as to why it's like a perpetual motion machine. Found one on wikipedia!

http://en.wikipedia.org/wiki/Woodward_effect

If allowed to accelerate horizontally on a frictionless plane, the kinetic energy would grow as the square of the elapsed time, while the input energy grows linearly with time. Thus, after a characteristic time T, "free" energy would appear to be continuously available in ever-increasing amounts

Wiki says Woodward doesn't deny this, but says that the energy comes from the rest of the universe. Sounds like perpetual motion to me!

Not that I'm defending the Mach Effect, but the appearances can be deceiving. Unpowered planetary slingshots look pretty suspect at first from an energy conservation standpoint, but that's because your gut reaction goes against using an entire planet as reaction mass.

[grondilu]

I looked around a bit for a more "intuitive" explanation as to why it's like a perpetual motion machine. Found one on wikipedia!

http://en.wikipedia.org/wiki/Woodward_effect

If allowed to accelerate horizontally on a frictionless plane, the kinetic energy would grow as the square of the elapsed time, while the input energy grows linearly with time. Thus, after a characteristic time T, "free" energy would appear to be continuously available in ever-increasing amounts

Wiki says Woodward doesn't deny this, but says that the energy comes from the rest of the universe. Sounds like perpetual motion to me!

Imagine you're in interstellar space, with almost no speed compared to the closest star, and you slowly fell towards it.  Is it perpetual motion to you?  Of course not.

To me there is suspicion of perpetual motion whenever a process claims it fuels itself.  I still don't understand Woodward's effect but so far it really does not seem to be anything like that.

[antiquark]

Has Woodward ever specified the maximum efficiency of his drive? For example, if you had a 1kg mass, and you powered his system with a 1 watt power supply, how fast would the mass accelerate?

[grondilu]

Has Woodward ever specified the maximum efficiency of his drive? For example, if you had a 1kg mass, and you powered his system with a 1 watt power supply, how fast would the mass accelerate?

The efficiency would not be related to this kilogram in any way, as the device would release a kind of energy due to the existence of surrounding celestial bodies.

Kind of when we discovered nuclear fission in chain reaction.  The output energy was not related in anyway to whatever energy you needed to enrich uranium.

Edit.

I'll try not to avoid your question anyway.  As I understand it, the Woodward effect is supposed to alter the mass.   So you can actually increase your speed while keeping  the same kinetic energy, since you had reduced your mass.  This makes your reasoning with an energy supply and one kilogram mass quite not appropriated.

[93143]

As I understand it, the Woodward effect is supposed to alter the mass.   So you can actually increase your speed while keeping  the same kinetic energy, since you had reduced your mass.

No, that's not how that works.  First off, the mass fluctuations are transient, and you still have to explain the difference in velocity between the states before the drive was turned on and after it was turned off (= difference in kinetic energy, because m1 = m2).

Second, your proposed scenario breaks Galilean invariance.  Momentum and kinetic energy (at least, translational kinetic energy calculated for a single body, which is not a real energy) are frame-dependent.  You can't accelerate just by changing your mass.  You have to say where the mass went, and how fast, and then you're back to a conventional rocket.

[grondilu]

No, that's not how that works.  First off, the mass fluctuations are transient, and you still have to explain the difference in velocity between the states before the drive was turned on and after it was turned off (= difference in kinetic energy, because m1 = m2).

There is not necessarily a difference of velocity.

Momentum and kinetic energy (at least, translational kinetic energy calculated for a single body, which is not a real energy) are frame-dependent.  You can't accelerate just by changing your mass.

That's no what I was trying to say anyway.  I'm not sure I understand exactly how from Woodward's effect you get acceleration.  It seems there are several possibilities, including antigravity, according to John Cramer:

« The question of burning interest to SF readers and writers is whether the weight reduction effect can be made large enough to produce actual lift against gravity. The answer appears to be yes. The weight reduction magnitude depends on the product of the mass variation and the acceleration applied to the varying mass by the piezoelectric motion device. The size of the mass variation depends on the amount of electric power flowing to the capacitor and on the frequency f of its charging current. The magnitude of the applied acceleration depends on the distance "stroke" of the piezoelectric motion device and on the square of the frequency (f2) at which it is operated. This means that the overall size of the weight reduction should grow as the third power of the driving frequency (f3).

Woodward's measurements at a frequency of about 10 kHz (a rather modest audio frequency) observed a weight change of about 1 part in 1000. Increasing the frequency by a factor of 20 to 200 kHz while holding the other variables fixed (if that is possible) should make the weight reduction considerably larger than the weight itself, therefore achieving lift. In other words, Woodward's effect, if it is real, should be usable as an antigravity device or a space drive, in the sense that these terms are normally used in science fiction. »

http://www.npl.washington.edu/AV/altvw83.html

[cuddihy]

I don't understand your focus on the weight or apparent weight of the active mass.  Nothing terribly interesting happening there, the amount of mass actually experiencing the effect is very small, and it's a transient. It's the apparent change in inertia that really matters, because with the push that is what provides the useful force.

[Robotbeat]

Anyone well-versed in physics care to comment on this criticism?

"If you break conservation of momentum, you break the 1st law. If you manage to magically nonlocally transfer momentum with the rest of the universe that happens to be in your exact reference frame you break the second law (and quite a lot that we assume about how the universe works with respect to nonlocal interaction.) If you have a drive that reacts with the average reference frame of the rest of the universe and has an 'efficiency' that is relative to the difference in that reference frame, you have a preferred reference frame and break the principle of relativity.
If this experiment isn't in error (and it almost certainly is) then one of those has to go."

I've heard this claim quite often -- that mach effects break the laws of thermodynamics, but this is the first I've heard that it violates the principle of relativity. However, I have a hard time believing Dr. Woodward would waste his time on something that so obviously breaks fundamental laws of physics, or that this massive implication wouldn't have been caught in the peer-review process, or by anyone over the last decade.

Everything about it obviously breaks the fundamental laws of physics, starting with (local) conservation of momentum.

Of all these fancy propellant-less propulsion ideas relying on new physics, they have these things in common:
1) Relying on wishful thinking as the impetus.
2) Using a veil of mathematics (pulled out of who-knows-where) to keep otherwise reasonable people from being able to quickly shoot down the result. But really, if it violates the more well-accepted laws of physics, that's good enough for it to be invalid. And if not, it should be noble prize worthy. But of course, they pursue the funding-for-advanced-propulsion route because they're primarily motivated by my first point (1), not by necessarily trying to develop a coherent and empirically verifiable view of the world.


Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool. --Richard Feynman


Also: http://xkcd.com/1166/

[grondilu]

Everything about it obviously breaks the fundamental laws of physics, starting with (local) conservation of momentum.

Are you even sure about that?  It really does not seem obvious to me.

Woodward derives his formula from the special relativistic version of Newton's second law.  In other words, he makes sure the four-force acting on the system is equal to the proper time derivative of the four-momentum.  So it is not supposed to violate momentum conservation.  Not even locally.

The only thing new compared to mainstream physics is the origin of inertial forces:

« Inertial reaction forces in objects subjected to accelera-
tions are produced by the interaction of the accelerated ob-
jects with a field - they are not the immediate consequence
only of some inherent property of the object - and they are
real, not fictitious. »

http://physics.fullerton.edu/~jimw/MUSH.pdf

Which is a model of Mach's principle.   From an epistemologic point of view, it seems totally legit to me:  Woodward (and Sciala) try to put some maths behind a physical principle, so they can deduce an effect and then determine experimentally if it is real or not.

Do you have a better idea on how to test Mach's principle?

[grondilu]

I don't understand your focus on the weight or apparent weight of the active mass.  Nothing terribly interesting happening there, the amount of mass actually experiencing the effect is very small, and it's a transient. It's the apparent change in inertia that really matters, because with the push that is what provides the useful force.

You say you don't understand the focus on weight and then you say that what matters is  change of inertia.  Well, according to general relativity, isn't there an exact correspondence between gravitational mass (aka. weight) and inertial mass (the tendency to resist to an external force)?

[KelvinZero]

I looked around a bit for a more "intuitive" explanation as to why it's like a perpetual motion machine. Found one on wikipedia!

http://en.wikipedia.org/wiki/Woodward_effect

If allowed to accelerate horizontally on a frictionless plane, the kinetic energy would grow as the square of the elapsed time, while the input energy grows linearly with time. Thus, after a characteristic time T, "free" energy would appear to be continuously available in ever-increasing amounts

Wiki says Woodward doesn't deny this, but says that the energy comes from the rest of the universe. Sounds like perpetual motion to me!

Btw there was a discussion of this back here:
http://forum.nasaspaceflight.com/index.php?topic=13020.msg977623#msg977623

[Robotbeat]

It clearly violates local conservation of momentum in any practical, testable sense.

[grondilu]

It clearly violates local conservation of momentum in any practical, testable sense.

Why?   Momentum is conserved only if there is no external force.  That's why when you fell off the ground, you don't say gravity violates conservation of momentum.  Because you know earth applies a force on you.

Woodward claims inertial forces come from a field.   So if you look at a device using Woodward's effect and you see what you interpret as a change of momentum, it is just the effect of the inertial force.