*Gravity and Inertia in General Relativity DOI: http://dx.doi.org/10.5772/intechopen.99760*

depends on the gravitational induction of inertia, a prediction that is not expected in the absence of inductive inertia. As it turns out, such a prediction exists, though it was not envisaged as a test of gravitational inertia induction when it was constructed. It is the prediction that if the local proper mass/energy density in a given region of spacetime is made to fluctuate, and that region is simultaneously subjected to a large proper acceleration to make manifest the inertial reaction gravitational field due to cosmic matter currents, that field vastly amplifies the magnitude of the masa/energy fluctuation.

This predicted rest mass fluctuation is a normally unobserved transient effect that is only obvious in special circumstances when it is sought. Those circumstances are the production of thrust in small systems, seemingly without the use of propellant, by coupling to the gravitational field of the universe through the mass fluctuations driven a stack of piezoelectric disks clamped to a brass reaction mass with an aluminum cap and screws. This is described in the precursor to this paper [12]. A device of this sort is show here in **Figure 1**. In order to maximize the oscillations of this device it is mounted using small linear ball bushings in ears on a flange on the reaction mass. The device is supported by rods in an aluminum frame as shown in **Figure 2**. A device like that in **Figure 1** has a mass of about 140 gms, whereas the support frame has a mass of about 60 gms. Work with devices like those shown in **Figures 1** and **2** commenced in the summer of 2020 using a high sensitivity torsion balance used in previous work. Large effects were produced. So large that the torsion balance was abandoned. But not until all of the various test for a genuine effect were completed.

The experiment was moved out of the balance vacuum chamber and onto a cantilever. Force generated in the device was measured by recording changes in the

### **Figure 1.**

*A Mach effect gravity assist (MEGA) impulse engine element. Eight 19 mm diameter by 2 mm thick led zirconium titanate disks are clamped between the aluminum cap and brass reaction mass. Linear ball bushings are fitted in the "ears" on the reaction mass.*

### **Figure 2.**

*A device like that in Figure 1 mounted on steel rods in an aluminum frame. The device is centered in the frame on the rods by very soft springs that convey very low frequency and stationary forces to the frame without communicating any high frequency vibration.*

position of the device on the rods with a Philtec position sensor. Typical results with this arrangement are reported in [12].

The chief criticism that has been advanced of the Mach effects project is that the measured thrusts were not due to any real effect. Rather, they allegedly arose from simple vibration in the systems – so-called "Newtonian vibrational artifacts". Those of us working on the project, of course, had been careful to exclude such false positives. But those determined to believe that Mach effects do not exist persisted. Indeed, they still persist, notwithstanding that we have increased the forces generated by these devices by two to three orders of magnitude [13]. And this performance increase was achieved by isolating the strong vibrations in the device from the support structure using linear ball bushings in place of a simple rubber pad in earlier design devices. To quell lingering doubts about false positives arising from vibration, my partner in this work, Hal Fearn, resuscitated an antique air track to see if an air supported "glider" could be made to move thereupon. The results, for technical reasons, were equivocal. Hal then turned to a pendulum, made with a small plastic platform suspended by three fine nylon monofilament cords with length 1.9 m from the ceiling of our lab, This has been the force detection system in use for the past several months.
