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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."
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".
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?
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
I will take the option of seatbelts while sitting at the bridge of your spaceship, thank you very much.
Reverse engineering things like Star Trek to come up with plausible explanations is lots of fun.
My take on near misses with photon torpedoes making "bang" sounds and throwing people around the bridge (besides the needs of dramatic presentation).
- Photon torpedoes are established as matter-antimatter nuclear bombs.
- These can be expected to produce some extreme EMP as a side-effect of their detonation and the "gamma light" from it striking any nearby matter.
- The artificial gravity / inertial compensation for multi-G impulse engine thrust (and any oddball forces from warp drive and changes to it) has to be variable to handle such variable conditions.
- The EMP interferes with its control mechanism. Not enough to smear the crew like paint over a nearby bulkhead. But enough for a near-miss to throw them around in their seats and rattle the ship enough to create the "bang" sound in the air. (Perhaps also the "whoosh" of a passing spacecraft, due to an electromagnetic "wake" from its systems - though that was clearly established as use of artistic license after the soundless flybys in the first trial footage were unsatisfying.)
- The engineers made the artificial gravity system VERY reliable. (Note that it keeps working when most of the ship's mechanisms, including other life support, is on the fritz.) And they made it good enough to keep the crew largely intact through "impacts" that seriously degrade the other systems and structural integrity of the ship. But they weren't able to get it down to no noticeable effect.
- And the designers didn't add seatbelt-equivalents until the first movie (after Admiral Kirk, done with his five-year missino, had given them hell about it.) B-)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
"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...
Reverse engineering things like Star Trek to come up with plausible explanations is lots of fun.
Reverse engineering things like Star Trek to come up with plausible explanations is fucking stupid.
Just because something is stupid doesn't mean it isn't fun. Don't be a party pooper. Star Trek was good enough science fiction that many, many people working in both physics and engineering will point to Star Trek as inspiring them to pay attention in science class.
These days I prefer my reading a little more challenging, but if it wasn't for my Dad waking me up early to watch Captain Kirk shoot phasers at Klingons and punch out guys in rubber suits, I probably would have just learned how to play baseball or something.
Cool art gallery, if you're into that sort of thing.
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