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Inertial Mass Separate From Gravitational Mass?
CPerdue writes with this excerpt from the MIT arXiv blog:
"The equivalence principle is one of the more fascinating ideas in modern science. It asserts that gravitational mass and inertial mass are identical. Einstein put it like this: the gravitational force we experience on Earth is identical to the force we would experience were we sitting in a spaceship accelerating at 1g. Newton might have said that the m in F=ma is the same as the ms in F=Gm1m2/r^2. ... All that changes today with the extraordinary work of Endre Kajari at the University of Ulm in Germany and a few buddies. They show how it is possible to create situations in the quantum world in which the effects of inertial and gravitational mass must be different. In fact, they show that these differences can be arbitrarily large."
Because once we have inertial drives, it's only a little while before we can colonize other planets.
The technology lens itself very well to that.
Would this lead to science fictions "Inertial Dampeners"?
I hope this caused some synapses to fire.
I would submit, courteously, that your mother's inertial and gravitic masses are arbitrarily large.
I realize that this all works only at that quantum level but what implications, if any, does this have for Einstein's general theory of relativity?
This ain't rocket surgery.
The "show" here is a proof, or rather, a calculation. They describe what kind of experiment can be used to test the calculation (on a Bose-Einstein condensate in free-fall).
The experiment isn't trivial, and these theoreticians won't be the ones doing it. They publish the theory, and everybody else looks at it to see if it's worth the time and money to set up an experiment. That's pretty much canonical science going on there, and doesn't merit being dismissed as "just a pretty theory".
We're unlikely to come up with anything better than crassical on this list.
They "show how it is possible to create situations", according to the summary. I think the experiment they outline in Appendix D of the paper satisfies that sentence.
"But we had purchased a reactionless, inertialess drive from the Outsiders. You may have guessed their price. We are still paying in installments. "
I seem to remember that in one of his other stories, the figure is a trillion stars, which was the worth of an entire, technologically advanced, planet.
Absolute statements are never true
In a gravity well, this explains why we need so much fuel to get out. But that assumes that inertial mass acts like gravitional mass. If we change that, then suddenly we use HIGH inertial mass but low gravitational mass as rocket exhaust, tremendously reducing the mass of the rocket's fuel, which has exponential gains in increasing the potential payload.
excitingthingstodo.blogspot.com
Assuming that these guys are right, would the presence of two different effects that we currently group together allow us to generate a model of the universe that doesn't require the vast majority of matter to exist as (currently) undetectable dark matter?
de von Ausfern -schplenden -schlitter -crasscrenbon -fried -digger -dangle -dungle -burstein -von -knacker -thrasher -apple -banger -horowitz -ticolensic -grander -knotty -spelltinkle -grandlich -grumblemeyer -spelterwasser -kürstlich -himbleeisen -bahnwagen -gutenabend -bitte -eine -nürnburger -bratwustle -gerspurten -mit -zweimache -luber -hundsfut -gumberaber -shönendanker -kalbsfleisch -mittler -raucher von Hautkopft auf Ulm would be proud of his fellow citizen.
Consider two giant bouncyballs in space, with the same inertial mass but where ball A has 4 times the gravitational mass of ball B. They start off some distance apart from each other, with velocity 0. As they attract each other, B will be accelerating 4 times faster than A since A has 4 times the gravity, and at one point they will meet. When they meet, A will have velocity -1 and B velocity +4. When they bounce off of each other, A will, naturally, have velocity +4 and B velocity -1. Now, B is still accelerating (or rather, decelerating) toward A 4 times faster than A is toward B, and when their relative velocity reaches 0, A will have velocity +3 and B will have velocity +3. Thus, each bounce accelerates the entire system by +3 with ZERO energy input, thus violating conservation of momentum and conservation of energy.
This is why any universe with a concept of conservation of energy and/or momentum must have the property inertial mass = gravitational mass. Now, if we can somehow break this rule with energy input, those of us interested in interstellar travel might have a completely new type of engine on our hands.
Neutron: Electrically neutral particle. One of the particles out of which atomic nuclei are built.
Interferometry: Measurement of the interference of waves. Remember that according to quantum mechanics, particles also show wave-like properties, especially interference.
The Tao of math: The numbers you can count are not the real numbers.
Imagine if you could lift an aircraft carrier sized ship in to space with nearly no energy, then accelerate to .999 light speed with no more thrust than a model rocket.
Note that one situation means low/zero gravitic mass, the other means low/zero inertial mass. You might be able to arbitrarily control both. You might be able to trade one off for another. Or maybe only modify one. Also, the problems with SR and QM are at a small scale, so your aircraft carrier might only be one atom in diameter or something.
Finally, I haven't read the paper, but it'll be interesting to see how it gets around various perpetual motion type problems. Right off the top of my head, extracting energy from a pendulum where gravitic and inertial mass are different and varying is going to be a serious issue.
Changing inertial mass would do pretty weird things to rotating flywheels. I suppose you could make a spinning flywheel break apart with immense violence at a very low rotational speed. Or rotate a spinning flywheel at insane speeds without it flying apart. All at the same stored energy level. Theres probably a perpetual motion machine that would involve extracting constant energy at a constant torque at high vs low RPMs.
Similar problems at a quantum scale. Otherwise it would be too easy to accelerate two beams of "reduced inertial mass" deuterium to an arbitrarily high velocity and then increase their gravitic mass at the collision point until they fuse.
Finally, the most interesting apps might be arbitrarily increasing inertial and gravitic mass. Increasing gravitic mass would make gravity wave detectors much simpler to make. The odds of increasing the gravitic mass of something small on a spacecraft to something large like a planet seem unlikely aka artifical gravity. Increasing inertial mass might be useful for weapons, armor, pretty much anywhere you use lead, tungsten, or DU.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Yeah, I mean, quantum tunneling? Quantum confinement? Those effects totally just cancel out and never do us any good!
C'mon guys. I've never seen a response so short-sighted as to discard a physics breakthrough so quickly.
Not quite. Acceleration starts at a specific point and "pushes" its way through the object at the speed of sound in the material of the object. If you had a 10 mile long metal bar and were strong enough to shove one end, the other end wouldn't move instantly. Your force would start a compression wave along the metal bar, traveling at the speed of sound though the metal, until it reached the other end. Same with a rocket, the engines apply acceleration at their connection point and the acceleration pushes its way through the materiel. This is why they have to be built out of such strong stuff, it has to be able to withstand the compression forces of the acceleration without fracturing due to stress.
What he has discovered is that it is the PLASMA above the properly charged surface that creates a gravity shielding effect, and shielding includes inversion. Yes, -1g is possible.
Except it don't work on water..
which is totally what she said
Seriously, how did that get rated up? Do the mods just say "oh that sounds interesting" and mod it up without even looking at the links or think about what the person is saying? Yes, I'm sure some random guy on the internet has come up with a convenient, easy, reproducible way to produce an anti-gravity device and it somehow slipped our attention. Thanks for filling us in GP!
I would think this means we have a basis for making quantitative measurements of what happens where GR and QM collide.
Not quite. They make no assumptions about GR in the article, what they have done is come up with a way to test one of the assumptions of GR - assuming the article passes peer review, arXiv is just a preprint server. There are too possible outcomes to the test they propose: m_i=m_g or m_i!=m_g. In the first case nothing has changed and in the second case one of GR's core assumptions has been dismantled so GR cannot be a fundamental theory since there is a phenomenon which it cannot explain. Hence QM and GR will never 'collide' because GR will have disappeared to be replaced by something else - possibly something which QM has no problem with.
My personal guess is that any such experiment will show that m_i=m_g but it will be an interesting test to do and potentially result in a far more accurate test of the equivalence principle.
The key part is the null-grav Bose-condensate at the base. When the temperature falls below 91 micro-kelvins, the resulting phase-change decouples inertial mass from equivalent mass and the gravitational force disappears.
There a few bugs to be worked out however. First, the grav-shield must be aligned within ten arc-seconds perpendicular to main gravitational body (Earth) or gravity leaks through. Second, stray cosmic rays have the disturbing habit of energizing the condensate about the phase-change temp and destroying the null-grav effect. I hope to have fixes by next week.
The standard crackpot "a single equation" makes me want to cry, but the "see t-shirt below" part more than makes up for it.
You may be correct about what scientists think they are are saying, but it rarely comes out that way. A physicist may say something like "FTL drive is impossible," and he may be thinking, at least until someone discovers a way to transform the underlying space-time matrix, but what people hear is "That's the final word, and it will never change."
If the "until someone discovers differently" qualifier went without saying, people wouldn't be starting these ridiculous movements like "Mundane Science Fiction."
"Professor" Aquino is widely known as a total nut. For Newton's sake, his theory "includes not only force particles and matter particles, not only general relativity and Quantum Gravity, but also a theory of consciousness"!! He can't publish his papers at the "Journal of New Energy"! Heck, one of his abstracts starts with "The existence of imaginary mass associated to the neutrino is already well-known" (and as a particle physicist, I've never seen any theory or experiment that even suggests an imaginary mass). He was worked at INPE (which is a very respected research institution) in a data-taking-monkey position; then got a job at the Maranhão state university (where there is NO research at all). He is listed at UEMA as having only a masters' degree (no PhD, so he can't have a research position). Please, don't mention him on an article about science. It's just like mentioning a 1940 VW Beetle when discussing today's F1 cars.
If he's right, they'll call it that "Kajari Drive". That just doesn't ring for me. We need someone else to refine this and make it go. An Archer maybe, or a Cochrane. Now those are names a real space drive can wear. Hell even inter-compartment conduits get names like Jefferies Tubes. Kajari? No way. He can have an episode of his own when they serialize history (as we know they have, so we can see it but consider it fiction thus avoiding paradox), but not the name of the drive.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
"The equivalence principle is one of the corner stones of general relativity. Now physicists have used quantum mechanics to show how it fails."
Alternatively, they could choose to look at this equivalent assertion: The wave-particle duality of matter is one of the cornerstones of quantum mechanics. Now physicists have used general relativity to show how quantum mechanics fails.
Of course, in actuality, they haven't shown anything yet...
The process of science goes back and forth between theory and experiment. The theory step is important, since it helps guide experiment.
So it's not "just" a pretty theory, in the sense of one that sits on the shelf and doesn't do anything. It makes prescriptions; it's participating in the back-and-forth between theoreticians and experimentalists.
Assuming the acceleration is provided by mechanical means. But if the body in question is a conductor and the accelerating field is a uniform magnetic field, the acceleration is applied to all the particles in the body at the same time and in the same amount. Provided the accelerating force is uniform, it can still, theoretically be distinguished from gravity by its lack of a gradient.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
Oh, I can easily write all equations of Physics into one equation.
To see how it works, let's assume I want to "unify" the Schrödinger equation and Einsteins field equation (don't worry about the fact that the Schrödinger equation is non-relativistic ...).
Schrödinger: i hbar d/dt psi = H psi [d here should be the partial derivative sign]
Einstein: G = 8 pi gamma/c^4 T [gamma here is the gravitational constant, because G is already used for the Einstein curvature tensor]
The first step is to bring all terms to the left side:
Schrödinger: H psi - i hbar d/dt psi = 0
Einstein: G - 8 pi gamma/c^4 T = 0
Note, however that the "0" in the first equation is a null vector in the quantum mechanical Hilbert space, while in the second equation, it's a tensor in spacetime. Those are not compatible. However, in both cases, we can choose a norm (in the first case, the standard Hilbert space norm can be used; in the second case, any matrix norm will do). Note that the norm need not to make physical sense; the only thing we need is that it maps to the non-negative real numbers, and only the zero object of the respective quantity is mapped to the real number zero. Denoting both norms with ||...||, we get:
Schrödinger: ||H psi - i hbar d/dt psi|| = 0
Einstein: ||G - 8 pi gamma/c^4 T|| = 0
Now we have two non-negative real numbers which shall be zero. Their sum is zero exactly if each one of them is zero. Therefore we can combine the equations into one:
||H psi - i hbar d/dt psi|| + ||G - 8 pi gamma/c^4 T|| = 0
From this equation, one can easily derive both Einstein's field equation and Schrödinger's equation. Therefore I just unified quantum mechanics and general relativity. :-)
The Tao of math: The numbers you can count are not the real numbers.
The point is that, according to the euivalence principle, X g of acceleration due to gravity is indistinguishable from X g of acceleration due to anything else. The article used the specific example of the 1 g you feel at the surface of the Earth.
Ok, this question has been bugging me for a short while, and this seems like the ideal place to bring it up, since it's somewhat on topic:
(1) We're always told how inertial mass and gravitational mass, while two distinct things, are always the same (up until today, anyway).
(2) We also know that mass increases with speed, which we use to explain why objects can't accelerate to the speed of light (infinite force required to overcome inertia, etc.)
(3) This would logically imply that gravitational mass increases with speed as well, and would further mean that gravitational attraction between two objects depends not only on their separation, but also on their relative velocities.
Are my conclusions correct? 'Cause that's kinda counterintuitive (although that's what tends to happen at the frontier of physics).
Of course I didn't RTFA.
I don't have a lot of gravitational mass ... it's my bones that have a lot of inertia.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."