From: Bruce Maccabee <firstname.lastname@example.org> Date: Wed, 7 Apr 1999 22:18:14 -0400 Fwd Date: Thu, 08 Apr 1999 15:27:20 -0400 Subject: Re: Krauss' Faulty Physics >From: David Rudiak <DRudiak@aol.com> >Date: Tue, 6 Apr 1999 18:24:11 EDT >Subject: Krauss' Faulty Physics >To: email@example.com >The following exchange occurred between Jeff Rense and Dr. >Lawrence Kraus on the Rense show during the debate between Kraus >and Stanton Friedman. >Rense mentioned a recent patent by Ernest Shearing (sp?) for >passenger protection in an electromagnetically propelled >vehicle. The passenger would be surrounded by a superconductor >(SC), which would exclude any electromagnetic fields from the >interior. In addition, the SC shield would be surrounded by SC >magnets, which Shearing said would also provide protection >against the effects of high acceleration or high gravity fields >by induction of eddy currents in the SC walls.. >This was Kraus' response: >"Until it got to gravity, it didn't sound completely crazy. >Indeed, superconductors do a very good job of shielding against >magnetic fields. Magnetic fields, of course, are not very >strong at all. In the region of the Earth we don't use them >very much for propulsion. But gravity fields don't produce any >currents and aren't shielded by anything superconducting, and >therefore, a superconductor doesn't shield you against any type >of gravitational acceleration in any way, shape, or form." >Despite Dr. Kraus' flippant dismissal, he is simply dead wrong >about this. <snip> However, I think for those not expert in Newtonion physics and electromagnetics we should keep something straight here, namely, the difference between "gravitational acceleration" and "inertial acceleration". Shearing began the potential confusion by stating that a strong magnetic field would protect against the effects of high acceleration and "strong gravitational fields." Kraus apparently agreed wth protection against acceleration but then responded that he didn't believe it would protect against a strong gravitational acceleration. I agree with Kraus that, so far as we know, the superconducting material won't shield against "gravitational acceleration." But note that Kraus apparently did agree that the magnetic effects might protect passengers from "inertial acceleration." In a vehicle, the gravitational acceleration is irrelevant as long as the vehicle is traveling horizontally. The intent of the magnetic field as described by Rudiak is to help reduce damage to the passengers by eliminating "differential inertial acceleration" which is the standard Newtonian second law acceleration: if a body changes its velocity, the rate of change of velocity, i.e. acceleration, a, is proportional to the applied force, f, and the constant of prportionality is the the inverse of the "inertial mass": a = (1/m)f = f/m. the more familiar form is f = ma. This law is applicable to point masses or perfectly rigid objects (whatever they might be). Here "rigid" does have a real world meaning, namely, of a force is applied to one surface, then that same force is "propagated" to the opposite surface (in the same direction as the force) in a time VERY SHORT compared to the time for the first surface to move an appreciable amount. IN other words, "rigid" means very little compression when pushed on by a force. Gravitation, on the other hand is a Newtonion force that depends upon the gravitational mass: f' = mg where g is the strength of the local gravitational field. The gravitation law was also formulated for point masses or rigid objects. However, rigid here means ANY body, no matter how "squishable" as long as the gravitational force is uniform over the extent of the body (i.e., no gravitational gradient over the length of the body). The neat thing about the gravitational force is that it acts on all portions of the object at the same time. Hence if there is no gravitational gradient, all portions feel the same acceleration force. (Here I am not being Einsteinian at all!). This would not be the case in a "high gravitational field" where there is a substantial gradient in the gravitational force (say, near a black hole). In that case the gravitational force on one side of an object might be greater than that on the opposite side with the consequence that the object responds to the differential force by stetching. So far as I know, neither the superconducting metal surrounding nor the strong magnetic field would protect against the effects of a large gravitational gradient. The frog example cited by Rudiak is not a case of inertial acceleration, and the frog was not shielded from gravity. It's weight (gravitational downward force) was balanced by the magnetic (diamagnetic) force of (I presume) ionic currents within the "frogstuff" that were created by any tendency of the frog to move (downward) within the magnetic field. There was no "acceleration" (except in the general sense that gravitational force appears as if it were an acceleration). The frog didn't move _relative_ to the magnet (which, in turn didn't move relative to the earth) Also, the gravitational gradient at the surface of the earth is _very_ small so the frog wasn't stretched (well, maybe stretched some angstoms). In the case of horizontal acceleration of a vehicle at the surface of the earth the gravitational force will always be downward, but the inertial force resisting acceleration will be horizontal. It is the horizontal force that is the one to "fear" if it is large enough. In a non-protected situation, such as sitting in a chair, if the drive motors start to accelerate the chair (relative to the earth), the chair pushes against your back (assuming you are sitting in the chair). Your back pushes against your "middle" and, in the meantime (very short time, microseconds) your front, which has not yet started to move because of "inertia" also pushes against your middle.... with the result that your middle gets squished between back and front (recipe for human jello). This is the effect of "differential acceleration" which arises because the molecules of your front are not being forced to move at exactly the same time as the molcules of your back. If your front (and middle) could be accelerated at exactly the same time (and by exactly the same amount) as your back there would be no squish (sorry, jello). Problem: how to avoid "differential acceleration," As Rudiak has so well pointed out, the magnetic field approach can accomplish this. You are immersed in the magnetic field which is created by a HUGE (?) magnet. (Whether you are also levitated as was the frog is not relevant at this time; you could be sitting normally). The field is directed along the direction of the acceleration. powerful machinery (or a rocket) accelerates the magnet which, in turn, accelerates its field (the field moves with the magnet; any radiation effects ignored), and the field accelerates all the diamagnetic molecules in your body at the same time (under ideal circumstances) so that there is no "differential acceleration" of the various parts of your body. By this means the "vehicle" in which you are sitting can accelerate at a great rate without converting you into a 2 dimensional projection of your former self (i.e., flat against "the wall"). Note that the field has not removed or reduced your inertia. The force applied to the magnet to accelerate it plus you must be f = (Mmagnet + Myou) times (the desired acceleration). f = (Mm + My) a To recap: the strong magnetic field, making use of the diamagnetic effect of eddy currents within your body, can protect you against the "differential acceleration" effects of high acceleration. However, it is not a gravitational shield: if you are near a black hole you may find your body stretched by the gravitational gradient even if you are supported by a strong magnetic field unless, of course, the magnetic field is somehow configured to have the same gradient function (change in force with distance), but in the opposite direction, as the gravitational gradient. In other words, if you were in a uniform magnetic field that supported you "above" a black hole, "on average" you might not move, but your feet (closer to the hole) would be pulled harder than your head, so ...... this could be a way to increase yout height (a futuristic version of "the rack?"). All this previous discussion could be irrelevant if strong magnetic fields and field gradients are, themselves, dangerous.
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