Although by “object” I think that Mach would have been talking about a theoretical, non-divisible object. Even a single atom would be measurable, I would think, as the proton and electron could be individually measured.
I think the main question may not be so much the existence of the effect, but the practicality of it. If people doubt that Woodward’s device will never be able to produce more than a few milinewtons of force, it could become a cool science fair exhibit, but won’t ever be useful for pushing things around in space.
I think here you get at the heart of the matter, but also sort of prove the point:
If there is an object containing multiple atoms, then it is not “an” object for the purpose of counting how many objects there are in the universe. If you can break the thing down into smaller things, then it is actually just a collection of those smaller things. And those smaller things can interact with and be compared with each other.
I think the lone object in a universe would have to be the the most fundamental type of subatomic particle which could not be broken down into smaller particles.
At that point the idea of mass and velocity truly have no meaning because they imply some means to influence motion or interaction with other things, and there are no other things to move in comparison to or interact with.
What Lockheed knows is that they’ve put a lot of money into – and more importantly made a lot of money from – their current approach.
(Also, it’s entirely possible that they have a little project going on that more-or-less replicates this, but we haven’t heard about it. They’d want to develop it in a way that could be protected by patents.)
Yeah, I did sorta get the feeling we were in that kind of purely theoretical territory. It feels like a cheat to say that unmeasurable == nonexistent, though. Like the entire theoretical universe at that point should just vanish in a puff of logic.
Well, the whole theory of relativity, and modern physics, is, in some sense, about measurement—and about measurement in relation to other objects.
When we say “A twin sent off in a spaceship ages more slowly” we really do need to say “…ages more slowly than his other twin, left behind.” The notion of time- and space-dilation makes no sense at all without reference objects.
One object in space really does have no velocity, because velocity only has meaning in relation to other things. It’s not just a question of measurement, it’s that velocity is a nonsense word in a one-object universe.
Likewise, mass. What does it mean to have mass? It means you attract/are attracted to objects, and it means you have momentum when you move. But if you can’t move, and there are no other objects to attract, what can it possibly mean to have mass? Nothing, it’s a completely meaningless idea.
So it’s not just a question of terminology, or of silly logic. It really is true: terms such as velocity and mass are completely without meaning in a one-object universe.
Those look like reactor shielding bricks to me. I wouldn’t want to spend any time in that room without checking it with a geiger counter first… having been down that road once already, I am now very suspicious of all lead bricks. Especially lead bricks found laying around physics departments.
Yes, conservation of momentum is fundamental; it is just as fundamental as the conservation of mass/energy. If the laws of physics don’t depend on your position in space, you must have conservation of momentum, just as if the laws don’t depend on time, you get conservation of mass/energy. Emmy Noether showed that every conservation law is related to a symmetry.
Every time someone claims to demonstrate something like this, they always show a tiny effect in a noisy system (a very small “reactionless thrust” with all kinds of much larger motion going on). I’m sure that’s the case once again.
yabut… isn’t pretty much any measurement meaningless in this one-object universe? If you have absolutely no frame of reference to compare to, then size, time, mass, velocity, you-name-it would seem to be out the window. It’d be a struggle even to have more than one dimension any dimensions, wouldn’t it?
Which says a lot about frames of reference, but wouldn’t seem like it would have a lot of practical impact.
Except there is something that you could measure the particle against: the underlying spacetime manifold. Then one could still talk about the particle having a velocity with respect to various reference frames.
For example: A photon should still travel at the speed of light, even if we can’t know what direction it is going.
So very many people, having enjoyed Star Trek, take it on faith that we will get there one day. In such an environment, even the tiniest fluctuation becomes evidence.
It seems to me that one of the biggest changes in bOINGbOING from its early days is how quickly the current denizens dismiss possible challenges to physics orthodoxy. Is it my imagination, or have happy mutants become far less willing to encourage researchers attempting to reach outside the boundaries of academic dogma?
I take it as a given that any one commenter in here has far more specialized knowledge than a tag-team of physicists, mathematicians, and peer-reviewed journals. This is TEH BOING after all.
And in Maggie’s absence, no speculative science shall be let stood by the divine grace of His Holiness, Neil deGrasse Junior High Tyson.
I think that this does not break the Law of Conservation of Momentum, any more than a car accelerating from zero doesn’t break the law. In the car’s case, you don’t measure the system’s momentum by comparing the car’s momentum with its tailpipe-emission’s momentum, you instead look at the car and the planet it’s resting on, and say that the Earth gained or lost a minuscule amount of spin.
In this situation, the vehicle is not “pushing” against anything, but it is still interacting through all the other objects in the universe through gravity. Imagine it is accelerating towards a planet. The planet must also be accelerating towards it. And the faster it accelerates towards the planet, the faster the planet accelerates towards it, because the distance – and so the force – is converging more rapidly.
So, you say, why is that different that the regular case? A planet is pulled towards a regular spaceship in exactly the same way, if it had a normal engine, right? Well, I’d say not exactly. The planet is pulled slightly more in the Woodward Engine case, because the mass of the spaceship remains constant as it’s approaching. In the regular case, the mass is decreasing (or, properly, is separating, and the propellant is flung further away and so has less gravitational effect on the planet). This tiny extra thrust on the planet, I would suspect, would exactly balance out the momentum that would normally be donated to the propellant.
