Why does F=ma in Newton's Equation of Motion?
How does a gravitational field produce a force?
Why are inertial mass and gravitational mass the same?

It appears that all three of these seemingly axiomatic foundational questions have an
answer involving an identical physical process: interaction between the electromagnetic quantum
vacuum and the fundamental charged particles (quarks and electrons) constituting matter. All three
of these effects and equalities can be traced back to the appearance of a specific asymmetry in the
otherwise uniform and isotropic electromagnetic quantum vacuum. The key insight is that the asymmetry
in an accelerating reference frame in flat spacetime is identical to that in a stationary reference
frame in curved spacetime.
It was shown by Unruh and by Davies that an accelerating detector will
experience a Planckianlike heat bath whose apparent ``temperature'' is a result of quantum vacuum
radiation. A tiny fraction of the (enormous)
electromagnetic quantum vacuum energy can emerge as real radiation under the appropriate conditions.
The existence of UnruhDavies radiation is now generally accepted and SLAC physicist Pisin Chen has
recently proposed an experiment to measure it. Rueda and Haisch
analyzed a related process and found that as perceived by an accelerating object, an energy and
momentum flux of radiation emerges from the electromagnetic quantum vacuum and that the strength of
this momentum flux proves to be proportional to acceleration. If this momentum flux is allowed to
interact with matter, presumably at the level of quarks and electrons, a reaction force is produced
that can be interpreted as the origin of Newton's F=ma. In this view, which we call the
quantum vacuum inertia hypothesis, matter resists acceleration not because of some innate
property of inertia, but rather because the electromagnetic quantum vacuum provides an
accelerationdependent drag force.
GR declares that gravity can be interpreted as spacetime curvature. Wheeler
coined the term geometrodynamics to describe this: the dynamics of objects subject to gravity is
determined by the geometry of fourdimensional spacetime. What geometrodynamics actually specifies is
the family of geodesics  the shortest fourdimensional distances between two points in spacetime
 in the presence of a gravitating body. Freelyfalling objects and light rays follow geodesics.
However when an object is prevented from following a geodetic trajectory, a force is experienced: the
wellknown force called weight. Where does this force come from? Or put another way, how does a
gravitational field exert a force on a non freelyfalling, fixed, object, such as an observer
standing on a scale on the Earth's surface? This proves to be the identical process as described in
the quantum vacuum inertia hypothesis.
In the SED approximation, the electromagnetic quantum vacuum is represented as propagating
electromagnetic waves. These should follow geodesics.
It can be shown that propagation along curved geodesics creates the identical electromagnetic
momentum flux with respect to a stationary fixed object as is the case for an accelerating object.
This is perfectly consistent with Einstein's fundamental assumption of the equivalence of gravitation
and acceleration. An object fixed above a gravitating body will perceive the electromagnetic quantum
vacuum to be accelerating past it, which is of course the same as the perception of the object when
it is doing the accelerating through the quantum vacuum. Another useful intuitive picture is to
imagine the downward deviation of tangential light rays near a gravitating body resulting in a net
downward force, somewhat analogous to radiation pressure, on a fixed object.
Thus in the case of gravity, it would be the electromagnetic momentum flux acting upon a fixed object
that creates the force known as weight, thereby answering the second question. The answer to the
third question then immediately follows. Since the same electromagnetic momentum flux would be seen
by either a fixed object in a gravitational field or an accelerating object in free space, the force
that is felt would be the same, hence the parameters we traditionally call inertial and
gravitational mass must be the same. This would explain the physical origin of the weak principle of
equivalence.
All of this is consistent with the mathematics of GR. What this view adds to physics is insight into
a specific physical process creating identical inertial and gravitational forces. What this view
hints at in terms of advanced propulsion technology is the possibility that by locally modifying
either the electromagnetic quantum vacuum and/or its interaction with matter, inertial and
gravitational forces could be modified or even nullified.
Primary Articles (See Scientific Articles for additional articles. Click here for new popularlevel overview by Marcus Chown.)
Quantum Vacuum and Inertial Reaction in Nonrelativistic QED
Hiroki Sunahata, Alfonso Rueda and Bernard Haisch, arXiv:1306.6036 [physics.genph] (2013).
Assessment of proposed electromagnetic quantum vacuum energy extraction methods
Garret Moddel, arXiv:0910.5893 (2009).
Gravity and the Quantum Vacuum Inertia Hypothesis
Alfonso Rueda & Bernard Haisch, Annalen der Physik, Vol. 14, No. 8, 479498 (2005).
Review of Experimental Concepts for Studying the Quantum Vacuum Fields
E. W. Davis, V. L. Teofilo, B. Haisch, H. E. Puthoff, L. J. Nickisch, A. Rueda and D. C. Cole, Space Technology and Applications International Forum (STAIF 2006), p. 1390 (2006).
Analysis of Orbital Decay Time for the Classical Hydrogen Atom Interacting with Circularly Polarized Electromagnetic Radiation
Daniel C. Cole & Yi Zou, Physical Review E, 69, 016601, (2004).
Inertial mass and the quantum vacuum fields
Bernard Haisch, Alfonso Rueda & York Dobyns, Annalen der Physik, Vol. 10, No. 5, 393414 (2001).
Stochastic nonrelativistic approach to gravity as originating from vacuum zeropoint field van der Waals forces
Daniel C. Cole, Alfonso Rueda, Konn Danley, Physical Review A, 63, 054101, (2001).
The Case for Inertia as a Vacuum Effect: a Reply to Woodward & Mahood
Y. Dobyns, A. Rueda & B.Haisch, Foundations of Physics, Vol. 30, No. 1, 59 (2000).
On the relation between a zeropointfieldinduced inertial effect and the Einsteinde Broglie formula
B. Haisch & A. Rueda, Physics Letters A, 268, 224, (2000).
Contribution to inertial mass by reaction of the vacuum to
accelerated motion
A. Rueda & B. Haisch, Foundations of Physics, Vol. 28, No. 7, pp. 10571108 (1998).
Inertial mass as reaction of the vacuum to acccelerated
motion
A. Rueda & B. Haisch, Physics Letters A, vol. 240, No. 3, pp. 115126, (1998).
Reply to Michel's "Comment on ZeroPoint Fluctuations and the Cosmological Constant"
B. Haisch & A. Rueda, Astrophysical Journal, 488, 563, (1997).
Quantum and classical statistics of the electromagnetic
zeropointfield
M. Ibison & B. Haisch, Physical Review A, 54, pp. 27372744, (1996).
Vacuum ZeroPoint Field Pressure Instability in Astrophysical Plasmas and the Formation of
Cosmic Voids
A. Rueda, B. Haisch & D.C. Cole, Astrophysical Journal, Vol. 445, pp. 716 (1995).
Inertia as a zeropointfield Lorentz force
B. Haisch, A. Rueda
& H.E. Puthoff, Physical Review A, Vol. 49, No. 2, pp. 678694 (1994).