arXiv:physics/9807023v2 [physics.gen-ph] 22 Jul 1998
Advances in the Proposed Electromagnetic Zero-Point Field Theory of Inertia
Solar & Astrophysics Labor atory, Lockheed Martin
3251 Hanover St., Palo Alto, CA 94304
Dept. of Electrical Engineering and Dept. of Physics & Astronomy
California State Univ., Long Beach, CA 90840
E-mail: arueda@cs ulb.edu
H. E. Puthoﬀ
Institute for Advanced Studies at Austin
4030 Braker Lane, Suite 300, Austin, TX 78759
Revised version of invited presentation at
34th AIAA/ASME/SAE/ASEE Joint Pr opulsion Conference and Exhibit
July 13–15, 1998, Cleveland, Ohio
AIAA paper 98-3143
A NASA-funded research eﬀort has been underway at the Lockheed Martin Advanced Technolog y Center
in Palo Alto and at California State University in Long Beach to develop and test a recently published theory
that Newton’s equatio n of motion c an be derived from Maxwell’s equations of electrodynamics as applied
to the zero-point ﬁeld (ZPF) of the quantum vacuum. In this Z PF-inertia theo ry, ma ss is postulated to
be not an intrinsic property of matter but rather a kind of electromagnetic drag force (which temporarily
is a place holder for a more gener al vacuum quantum ﬁelds reaction eﬀect) that proves to be acceleration
dependent by virtue of the spectral characteristics of the ZPF. The theory proposes that interactions be tween
the ZPF a nd matter take place at the level of qua rks and elec trons, hence would account for the mass of
a composite neutral particle such as the neutron. An e ﬀo rt to generalize the explor atory study of Haisch,
Rueda and P uthoﬀ (1994) into a proper relativistic formulation has been successful. Moreover the principle
of equiva lence implies that in this view gravitation would also be an eﬀect originated in the q uantum vacuum
along the lines proposed by Sakharov (1968). With regard to exotic propulsion we can deﬁnitively rule out
one s peculatively hypothesized mechanism: matter possessing negative inertial mass, a concept origina ted
by Bondi (1957) is shown to be logically impossible. On the other hand, the linked ZPF-inertia and ZPF-
gravity concepts open the conceptual possibility of manipulation of inertia and gravitation, since both are
postulated to be vacuum phenomena. It is hoped that this will someday translate into actual technological
potential, espe cially with re spect to spa c e c raft propulsion and future interstellar tr avel capa bility. A key
question is whether the propose d ZPF-matter interactions generating the phenomenon of mass might involve
one or more resonances. This is pr esently under investigation.
In an article in New Scientist science writer Robert Matthews (1995) summarizes the predictions of various
scientists: “Many researchers see the vacuum as a central ingredient of 21st ce ntury physics.” The reason
for this is that, despite its name, the vacuum is in fact far from empty. Create a perfect vacuum, devoid
of all matter and containing not a single (stable) particle, and that region of seemingly empty space will
actually be a seething quantum sea of ac tivity. Heisenberg’s uncertainty relations allow subatomic particles
to ﬂicker in and out of existence. Similar quantum processes apply to electromagnetic ﬁelds, and that is
1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
the origin of the electromagnetic zero-point ﬁeld (ZPF). The entire Universe is ﬁlled with a quantum sea of
electromagnetic zero-point energ y whose properties ar e the basis of Matthew’s predictive statement.
In 1994 we published a n analysis which proposed that the most fundamental property of matter — inertia
— could be explained as an electromagnetic force traceable to the ZPF (Haisch, Rueda and Puthoﬀ 1994;
HRP). The exploratory approach we used had two weaknesses: (1) the mathematical development was
quite complex, and (2) the calculations were dependent upon a simpliﬁed mo del to represent the interactions
between material objects and the ZPF. But in spite of these two limitations, our analysis yielded a remarkable
and unexpected result: that Newton’s e quation of motion, f = ma, re garded since 1687 as a postulate of
physics , could be derived from Maxwell’s laws of electrodynamics as applied to the ZPF. The implication is
that inertia is not an innate property of matter, rather it is an electromagnetically-derived force (or quantum
vacuum derived force in a future more general derivation). If this proves to be true, the p otential exists for
revolutionary technologies since the manipulation of electromagnetic phenomena is the basis of most modern
technology. I n particular, the manipulation of the vacuum electromagnetic ﬁelds is today the subject of
(vacuum) cavity quantum electr odynamics .
Thanks in part to a NASA research gra nt, we have made pro gress in strengthening the ba sis of the ZPF-
inertia hypothesis. We have been able to rederive the ZPF-inertia connection in a way that is mathematically
much more straightforward, that is not dependent upon the original simpliﬁed matter-ZPF interaction model,
and that — importantly — proves to be relativistic (Rueda & Haisch 1998a, 1998b). This increases our
conﬁdence considerably in the validity of the ZPF-inertia hypothesis.
We suggest that a change in paradigm regarding our conception of matter is not far oﬀ. If inertia proves to be
at least in part an electromagnetic force arising from interactions between qua rks and electrons and the ZPF,
this will do away with the concept o f inertial mass as a fundamental property of matter.
of equivalence then implies that gravitational mass will need to undergo an analogous reinterpreta tion. A
foundation for this was laid a lready 30 years ago by Sakharov (1968).
Lastly, the Einstein E = mc
relationship between mas s and energy will also b e cast in a diﬀerent light.
As it now stands this formula seems to state that one kind of “thing,” namely energy, can mysteriously be
transformed into a totally diﬀerent kind of “thing,” namely mass. . . and vice versa. It is proposed instead
that the E = mc
relationship is a statement about the kinetic energy that the ZPF ﬂuctuations induce on
the quarks and electrons co ns tituting matter (Puthoﬀ 1989a). We are us e d to interpreting this co nce ntration
of ener gy ass ociated with material objects as mass, but in fact this is more a matter of bookkeeping than
physics . Indeed the concept of mass itself in a ll its guises (inertial, gravitational and as relativistic rest
mass) appears to be a bookkeeping convenience. All we ever experience is the presence of a certain amount
of energy or the presence of certain forces. We traditionally account for these e nergies and forces in terms of
mass, but that app e ars now to be unnecessa ry. Interactions of the ZPF with quarks and electrons are what
physically underlie all these apparent manifestations of mass. This opens new possibilities.
Only ﬁfty years ago the concept of spac e travel was regarded by most, including scientists (who should have
known better), as science ﬁction: this in spite of the fact that the basic knowledge was already in place .
Details and technicalities, of course, were lacking, but the chief handicap was — more than anything — a
mindset that such things simply had to be impossible. Similar prejudices had been at work ﬁfty years pr ior
to that regarding ﬂight. We have come to a new millenium and the ﬁrst glimmerings of how to go about
ﬁnding a way to achieve interstellar travel have sta rted to appear on the horizon. A very modest — in terms
of cos t — but intellectually ambitious program has been established by NASA: The Breakthrough Propulsion
Physics Program (BPP). The rationale is stated as follows:
Vigier (1995), a former collaborator of Bohm and de Broglie, recently proposed that the Dirac vacuum
(that vast sea of virtual electrons and positrons in the vacuum strongly coupled to the ZPF) also contributes
to inertia. We have plans to jointly explore this idea in an extension of our original approach.
The Break through Propulsion Physics website is http://www.lerc.nasa.gov/WWW/bpp/
NASA is embarking on a new, small program called Breakthrough Propulsion Physics to seek
the ultimate breakthroughs in space transportation: (1) Propelling a vehicle without propel-
lant mass, (2) attaining the maximum transit speeds physically possible, and (3) creating new
energy production methods to powe r such devices. Because such goals are beyond the accumu-
lated scientiﬁc knowledge to date, further advances in science are sought, speciﬁcally advances
that focus on propulsion issues. Because such goals are presumably far from fruition, a special
emphasis of this program is to demonstr ate that near-term, credible, and measurable pr ogress
can be made. This program, managed by Marc Millis of Lewis Research Ce nter (LeRC) rep-
resents the combined eﬀorts of individuals from various NASA centers, other government labs,
univer sities and industry. This program is supported by the Space Transportation Research Of-
ﬁce of the Advanced Space Trans porta tion Program managed by Marshall Space Flight Center
The ﬁrst NASA BPP workshop was held in August 1997 to survey the territory and assess emerging physics
concepts. Several invited presentations discussed the ZPF vacuum ﬂuctuations, and this area of research
was given a high priority in a ranking process carried out as part of the meeting (Millis 1998 and refer e nce s
therein). In addition to the propos e d ZPF-inertia and ZPF-gravitation hypotheses, the possibility of extract-
ing energy and of generating forces from the vacuum ﬂuctuations were discussed. It has been shown that
extracting energy from the vac uum does not violate the laws of thermodynamics (Cole and Puthoﬀ 1993). As
for ZPF-related force s, the recent measurements of the Casimir force by Lamoreaux (1997) are in agreement
with theoretical predictions. Real, macroscopic forces can be attributed to ce rtain conﬁgurations of the ZPF,
such as in a Casimir cavity. We are proposing that inertia too is a Casimir-like acceleration-dependent drag
NEWTON’S EQUATION OF MOTION: f=ma
Physics recognizes the existence of four types of mass. (1) Inertial mass: the resistance to acceleration
known as inertia, deﬁned in Newton’s equation of motion, f = ma, a nd its relativistic generalizatio n. (2)
Active gravitational mass: the ability of matter to attract other matter via Newtonian gravitation, or, from
the perspective of general relativity, the ability to cur ve spacetime. (3) Passive gravitational mass: the
propensity of matter to respond to gravitational force s. (4) Relativistic rest mass: the relationship of the
mass of a body and the tota l energy available by perfect annihilation of the mass in the body, that is
expressed in the E = mc
relation of special relativity. These are very diﬀerent properties of matter, yet for
some reason they are qua ntitatively represented by the same parameter. One can imagine a universe, for
example, in which inertial mass, m
, and passive gravitational mas s, m
, were diﬀerent. . . but then objects
would not all fall with the same acceleration in a gravitational ﬁeld and there would be no principle of
equivalence to serve as the foundation of general relativity. One can imagine a universe in which active and
passive g ravitational mass were diﬀerent. . . but then Newton’s third law of equal and opposite forc e s would
be violated, and mechanics a s we know it would be impossible.
Consider inertial mass, m
. Exert a certain force, f, and mea sure a resultant acceleration, a. Let this process
take plac e under ideal conditions of zero friction. A nearly perfect example — excluding the very small
residual atmospher ic drag even at Shuttle altitudes — would be the force exerted by the Space Shuttle
engines and the acceleratio n of the Shuttle that results upon ﬁring. The inertial mass is a scalar coeﬃcient
linking these two mea sureable processe s f and a (sc alar since the vectors f and a point in the same direction).
However since we perceive a material object in the form of the Shuttle, we reify this m
attribute a property of mass to the object and then s ay that it is the mass of the object that causes the
resistance to acceleration. That is to say, for a given amount of m
residing in the matter o f an o bject it
takes so much force to achieve such a r ate of acceleration, which is embodied in f = ma. We thus attribute
mass to all material objects.
It is important to keep in mind that the actual direct measurement of the thing we call inertial mass, m
can only take place during acce leration. . . or deceleration which is simply acceleration directed opposite to
the existing velocity. We assume that an object always possesses something called mass even when it is not
accelerating, and proceed to calculate the momentum, m
v, and the kinetic energy, m
/2, of an object
moving at constant velo c ity with respect to us. But ther e can be no dir e c t evidence that an object possesses
mass unless it is being accelerated. The only way we can directly measure the momentum o r the kinetic
energy that we ca lc ulate is by bringing about a collision. But a collision necessarily involves dece leration. It
makes for g ood bookkeeping to assume that an object always carries with it a thing called mass, yielding a
certain momentum and kinetic energy, but this is necessarily an abstraction.
The momentum and kinetic energy depend upon relative motion, since no velocity is a bs olute. Move alongside
an object and its momentum and kinetic energy reduce to zer o. We argue that in a somewhat analogous
is not something that resides inna tely in a material object, but rather that it is an electromag netic
reaction force (per unit acceleratio n) that springs into e xis tence the instant an accele ration occur s, and
disappears as soon as the acceleration stops. It is, precisely as deﬁned in Newton’s f=ma, a coeﬃcient
linking force and acceleration. It is a force per unit acceleration tha t arises electrodynamically.
This may be brought into sharper focus by considering Newton’s third law. Newton’s third law states that
for every force there must be an equal and opposite reaction force, i.e. f = −f
. For s tationary or static
phenomena it is impossible to even conceive of an alternative: If the right hand is pressing against the left
hand with force f, then the left hand must press back against the right hand with the equal and oppositely-
directed reaction force, f
. How could one hand press against the other without the other pressing back? It
would violate a fundamental sy mmetry, since who or what is to say which hand is pressing a nd which is not.
Thus for static or stationary situations the balance of forces is the only imaginable circumstance.
If an agent exerts a force on a non-ﬁxed object, experience tells us that a reaction force also manifests against
the agent. But why is this so? The traditional explanation is that matter possesses inertial mass which by
its nature resists acceleration by pushing back upon the agent. The discovery that we have made is that,
on the contrary, there is a very speciﬁc electromagnetic origin for a reac tion force f
. Accelerated motion
through the electro magnetic zero-point ﬁeld (ZPF) of the quantum vacuum results in a reaction force. If one
analyses the ZPF using Maxwell’s equations of electrodynamics, one ﬁnds that f
a where m
an electromagnetic parameter with units o f mass. An electromagnetic reaction force (somewhat like a drag
force) arises tha t happ e ns to be proportional to acceleration. In other words, if one begins with Maxwell’s
equations as applied to the ZPF, one ﬁnds from the laws of electrodynamics that f
a and thus if one
assumes that the electrodynamic para meter m
really is the physical basis of mass, Newton’s third law of
equal and opposite forces, f = −f
, re sults in a derivation of f = ma from the electrodynamics of the ZPF.
That being the case, one can, in principle, dispense with the concept of inertial mass altogether. Matter,
consisting of charged particles (quarks and electrons) interacts with the electroma gnetic ZPF and this yields
a reaction force whenever a c celeration ta kes place and that is the cause of inertia.
THE ORIGIN OF THE ELECTROMAGNETIC ZERO-POINT FIELD
There are two v ie ws on the origin of the electromagnetic zero-point ﬁeld a s embodied in Quantum Elec-
trodynamics (QED) and Stochastic Electrodynamics (SED) respectively. The QED perspective is currently
regarded as “standard physics” and the arguments go as follows. The Heisenberg uncertainty relation sets a
fundamental limit on the precision with which conjugate quantities are allowed to be determined. The two
principal conjugate pairs are position and momentum such that ∆x∆p ≥ ¯h/2, and energy and time such that
∆E∆t ≥ ¯h/2 where ¯h is Planck’s constant, h , divided by 2π. It is a standard derivation in most textbooks
on qua ntum mechanics to work out the quantum version of a simple mechanical harmonic oscillator — a
mass on a spring — in this respect.
There are two non-classical results for a quantized harmonic oscillator. Firs t of all, the energy levels are
discrete and not continuous. By adding energy one can increase the amplitude of the oscillation, but only
in units of hν, where ν is the frequency in cycles per second. In other words, o ne can add or s ubtract
E = nhν of energy where n ≥ 0. The second quantum eﬀect stems from the fact that if an oscillator were
able to come completely to rest, ∆x would be zero and this would v iolate the ∆x∆p ≥ ¯h/2 limitation. The
result is that there is a minimum energy of E = hν/2, i.e. the oscillator energy ca n only take on the values
E = (n + 1/2)hν which can never become zero since n cannot be negative.
The arg ument is then made that the electromagnetic ﬁeld is analogous to a mechanical harmonic oscillator
since the electric and magnetic ﬁelds, E and B, are modes of oscilla ting plane waves (see e.g. Loudon 1983).
Each mode o f oscillation of the electromagnetic ﬁeld has a minimum energy of hν/2. The volumetric density
of modes between frequencies ν and ν + dν is given by the density of states function N
dν = (8π ν
Each state has a minimum hν/2 of energy, and using this density of states function and this minimum energ y
that we call the zero-point energy per state one can calculate the ZPF spectral energy density:
It is instructive to write the expression for zero-p oint spectral energy density side by side with blackbody
ρ(ν, T )dν =
The ﬁrst term (outside the parentheses) represents the mode density, and the terms inside the parentheses
are the average energy per mode of thermal radiation at temperature T plus the zero-point energy, hν/2,
which has no temperature dependence. Take away all thermal energy by formally letting T go to zero, and
one is still left with the zero-point term. The laws of quantum mechanics as applied to electromagnetic
radiation force the existence o f a background sea of zero-point-ﬁeld (ZPF) radiation.
Zero-point ra diation is a result of the application of quantum laws. It is traditionally assumed in quantum
theory, though, that the ZPF ca n fo r most practical purposes be ignored or subtracted away. The foundation
of SED is the exact opposite. It is assumed that the Z PF is as real as any other electromagnetic ﬁeld. As
to its origin, the assumption is made tha t for some reas on zero-point radiation just came with the Universe.
The justiﬁcation for this is that if one assumes that all of space is ﬁlled with ZPF radiation, a number of
quantum phenomena may be explained purely on the basis of classical physics including the presence of
background electromagnetic ﬂuctuations provided by the ZPF. The Heisenberg uncertainty re lation, in this
view, becomes then no t a result of the existence of quantum laws, but of the fact that there is a universal
perturbing ZPF acting on everything. The original motivation for developing SED was to see whether the
need for quantum laws separate from classical physics could thus be obviated entirely.
Philosophically, a universe ﬁlled — for reasons unknown — with a ZPF but with only one set of physical
laws (classical physics consisting of mechanics and electrodynamics), would appear to be on an equal footing
with a universe gover ned — for reasons unknown — by two distinct physical laws (classical and quantum).
In terms of physics, though, SED and QED are not on an equal footing, since SED has been succes sful in
providing a satisfactory alternative to only some q uantum phenomena (although this succ e ss does include
a classical ZPF-based deriva tion of the all-important blackbody s pectrum, cf. Boyer 1984). Some of this
is simply due to lack of eﬀort: The ratio of man-years devoted to development of QED is several orders of
magnitude greater than the expenditure so far on SED.
ACCELERATION AND THE DAVIES-UNRUH EFFECT
The ZPF spectral energy density of Eq. (1) would indeed be analogous to a spatially uniform constant oﬀset
that cancels out when considering energy ﬂuxes. However an important discovery was made in the mid-
1970’s that showed that the ZPF acquire s special characteristics when viewed from an accelera ting frame.
In connection with radiation from evaporating black holes as proposed by Hawking (1974), Davies (1975)
and Unruh (1976) determined that a P lanck-like component of the ZPF will arise in a uniformly-accelera ted
coordinate system having constant proper acceleration a (where |a| = a) with what amounts to an eﬀective
This “temperature” does not originate in emission from particles undergoing thermal motions.
by Davies, Dray and Manogue (19 96):
One of the most curious properties to be discussed in recent years is the prediction that an
observer who accelerates in the conventional quantum vacuum of Minkowski space will perceive
a bath of radiation, while an inertial observer of course perceives nothing. In the ca se of linear
acceleration, for which there exists an extensive literature, the response of a model particle
detector mimics the eﬀect of its being immersed in a bath of thermal radiatio n (the so-c alled
This “heat bath” is a quantum phenomenon. The “temp erature” is negligible for most accelerations. Only
in the extremely large gravitatio nal ﬁelds of black holes or in high-energy particle collisions can this become
signiﬁcant. This eﬀect has been studied using bo th QED (Davies 1975, Unruh 1976) and in the SED
formalism (Boyer 1980). For the classical SED case it is found that the spectrum is quasi-Planckian in T
Thus for the case of no true external thermal radiation (T = 0) but including this acceleratio n eﬀect (T
equation (1) becomes
where the acceleration-dependent pseudo-Planckian component is placed after the hν/2 term to indicate that
except for extreme accelerations (e.g. particle collisions at high energies) this term is negligibly small. While
these additional acceleration-dependent terms do not show any spatial asy mmetry in the expr ession for the
ZPF spectral energy density, certain asy mmetries do appear when the electromagnetic ﬁeld interactions with
charged particles are analy z ed, or when the momentum ﬂux of the ZPF is calculated. The ordinary plus a
radiation reaction terms in Eq. (12) of HRP mirror the two leading terms in Eq. (4).
THE ORIGIN OF INERTIA
Two independent approaches have demonstrated how a reaction force proportional to acceleration (f
a) arises out of the properties of the ZPF. The ﬁrst approach (HRP) was bas e d upon a simpliﬁed model
for how acc e le rated idealized quarks and electrons would interact with the ZPF. It identiﬁed the Lorentz
force arising from the sto chastically-averaged magnetic component of the ZPF, < B
>, as the basis of
. The new approach (Rueda and Haisch 1998a, 1998b) considers only the relativistic transformations of
the ZPF itself to an accelerated frame. We ﬁnd a non-zero stochastically-averag e d Poynting vector (c/4 π)
> which leads immediately to a no n-zero e le c tromagnetic Z PF-momentum ﬂux as viewed by
an accelerating object. If the quarks and electrons in such an a c c elerating object scatter this asymmetric
radiation, an acceleration-dependent reaction force f
arises. In fact in this new analysis the f
is the space-
part of a relativistic four-vector so that the resulting equation of motion is not simply the classical f = ma
expression, but ra ther the properly relativistic F = dP/dτ equation (that reduces exactly to f = ma for
In the ﬁrst approach a speciﬁc ZPF-matter interaction is needed to carry out the analysis. We used a
technique developed by Eins tein and Hopf (1911) and applied that to idealized particles (partons, in the
nomenclature of Feynman) treated as Planck oscillators. In the second approach, no speciﬁc ZPF-ma tter
interaction is necessary for the analy sis. Any scattering or absorption process will yield a reaction force
on the basis of a non-zer o electromagnetic momentum ﬂux. Presumably dipole scattering of the ZPF by
fundamental charged particles is the appropriate represe ntation, at least to ﬁrst order, since that can be
shown to be a detailed balance process in the non-accelerated case, i.e. dipole scattering by non-accelerated
One suspects of course that there is a deep connection between the fact that the ZPF spectrum that
arises in this fashion due to acc e le ration and the ordinary blackbody spectrum have identical form.
charged particles leaves the ZPF spectrum unchanged and isotropic (Puthoﬀ 1989b). In both approaches it
is assumed that the level of interaction is that of quarks and electrons, which would account for the inertial
mass of a composite neutral particle such as the neutron (udd).
The expression for inertial mass in HRP for an individual particle is
represents a damping constant for zitterbewegung oscillations .
This is not to be confused with
= 6.25 × 10
s (Jackson 1975) which is used for macroscopic electron os c illations in ordinary radiatio n-
matter inter actions. Γ
is a free parameter and Γ
. In Eq. (5) ω
represents an assumed cutoﬀ
frequency (in radians/s) for the ZPF spectrum and is also a free parameter.
The expression for inertial mass in Rueda and Haisch (1998a, 1998b) for an object with volume V
The interpretation of this is quite straightforward. The energy density of the ZPF (E q. 1) written in
terms of ω(= 2πν) is ρ
dω = ¯hω
which is the second term in the integral. The dimensionless
parameter η(ω) re presents the fraction of the ZPF ﬂux scattered a t each frequency. The total energy involved
“generating mass” is determined by the volume of the object, V
, and the division by c
converts the units
CAN INERTIAL MASS BE ALTERED?
The mass of a proton in e nergy units is ∼ 938 MeV. A proton is composed of two up (u) quarks and one
down (d) quark whose individual mas ses are ∼ 5 MeV for the u, and ∼ 10 Mev for the d. Thus the mass
of the uud combination constituting the pr oton is about 50 times more massive than the sum of the parts.
The same is true of a neutron (udd) whose mass is ∼ 940 MeV. This is clearly a naive argument given
the conceptual uncertainty of what “mass” actually means for an individual quark which cannot exist in
isolation. Nonetheless, taking this para dox at fa c e value does oﬀers a useful perspective for speculation.
The expression (Eq. 5) for m
of an individual particle as derived by HRP involves two free parameters,
. In HRP we assumed that ω
was some c uto ﬀ frequency dictated either by an actual cutoﬀ of
the ZPF spectrum (such as the Planck frequency) or by a minimum size of a pa rticle (such as the Planck
length). Let us assume that in place of a cuto ﬀ frequency there is a resonance frequency which is speciﬁc to
a given par ticle, call it ω
In the Dirac theory of the electron, the velocity operato r has eigenvalues of ±c. The motion of an
electron thus consists of two components: some average motion speciﬁc to a given physical circumstance
plus an inherent highly oscillatory component whose instantaneous velo c ity is ±c which Schr¨odinger named
zitterbewegung (cf. Huang 1952). The a mplitude of this zitterbewegung osc illation is on the order of the
Compton wavelength. From the perspective of the ZPF-inertia theory, the ZPF can induce such speed-
of-light ﬂuctuations since at this level the electron would be a massless point-charge. It is the Compton-
wavelength size “electron cloud” that acquires the measured electron inertia l mass of 512 keV in energy units
via a relationship like Eq. (5). The Γ
= 6.25 × 1 0
damping constant governs the motion of the “electron
cloud” whereas the Γ
applies to the internal zitterbewegung. This is an e xample of a n SED interpretation
of an apparent quantum phenomeon. The quantum size of the electron is its Compton wavelength. The
SED inter pretation would be one of a massless point charge driven by the ZPF to oscillate at ±c within a
Compton wavelength-size region of space. More on this is extensively discussed in two articles by Rueda
One can now imagine that a u-qua rk has a re sonance ω
(u) yielding m
= 5 MeV and that the d-quark
has a diﬀerent resonance ω
(d) yielding m
= 10 MeV (assuming the same Γ
). It would not be surpr ising
that a bound triad of quarks such as the uud or the udd would have a radically diﬀerent resonance as
an ensemble. The res onance of a mechanical system bears no simple relationship to the res onances o f its
component parts. On this basis it would be easy to see how the same three quarks could have a totally
diﬀerent mass collectively than individually.
This same line of r e asoning could be applied to the concept of mass defect. The sum of the masses of two
protons plus two neutrons is greater than the mass of a He nucleus. Ag ain, one can easily imagine the
resonance of a group o f 12 bound quarks in a He nucleus being diﬀerent than the sum of the resonances of
four groups of three bound quarks.
The advantage of this line of reasoning is that one does not have to convert mass into energy a nd vice versa.
The quarks themselves can remain basically unchanged entities, whereas the reso nances characterizing the
interaction between the quark ensemble and the ZPF vacuum vary. This view would not be at odds with
the conventional interpretation that in going from two free protons plus two free neutrons to one bound He
nucleus there is simply a change in potential (binding) energy taking place. That interpretation becomes
one way to “balance the books” but the change in resonance would serve equally well, yet without the need
to convert something material (mass) into something immaterial (energy). One would then interpret the
energy released during fusion in terms of a change in the kinetic energy of the zitterbewegung motions of
the quarks, which are driven by the underlying vacuum. In other words, change in mass bec omes instead
a change in the amount of energy involved in ZPF-qua rk interactions resulting from changes in resonance.
The energy released in fusion would be c oming from the ZPF.
We are suggesting that the mass o f a particle is determined by a resonance fr e quency, ω
, and that the mass
of a composite entity can be radically diﬀerent from the sum of the individual masses because of changes in
the resonances due to binding fo rces. If that pr oves to be the case, then one would also expect the mass of an
individual particle to be variable if a change in resonance can be induced via external boundary conditions.
This would be somewhat analagous to the well-known ability to change spontaneous emission (by more than
an order of magnitude) by eﬀectively placing an atom in an appropriate electromagnetic cavity.
We view inertia as a property a particle obtains in relation with the vacuum medium in which it is immersed.
We suggest that if one could somehow modify that vacuum medium then the mass of a particle or object in
it would change. There is in nature an outstanding anticipatory example of a very a nalogous feature that
is well known. This is the so-called “equivalent mass” or “eﬀective mass” concept that conducting e le c trons
and holes display when immersed in the crystal lattice of a semiconductor. The eﬀective mass parameter was
introduced long ago: see for example Smith (19 61). If an external agent applies a force to an electro n in the
conduction band or to a hole in the valence band, the inertia response obtained is not at all the one we would
exp ect for an o rdinary electron in empty space, but rather is quite diﬀerent from it depending on the details
of the particular crystal structure of the semiconductor in which the electr on (o r hole) is immersed. This is
why these particles are called “quasiparticles” in this situation with the eﬀective mass being the parameter
that characterizes their iner tial properties inside the s emiconductor medium. The inertial property of the
quasiparticle is due to the complex detailed interaction with the surrounding crystal lattice. The eﬀective
mass is modiﬁed if the potentials in the crystal structure change. Moreover if the crysta l structure has some
anisotropy, the eﬀective mass is no longer a scalar, but a tensor.
We can very reasonably ex pect that if the vacuum is modiﬁed, particularly at high energies, then our propos e d
inertial mass will also be modiﬁed and in particular, if one can manage to introduce an anisotropy in such
vacuum by modifying the structure of the vacuum modes in an anisotro pic way, the inertial mass may display
tensorial properties. Such an anisotropy is not unthinkable: A Casimir cavity is pr e cisely a structure that
introduces an anistropy of the ZPF mode structure. It, o f course, primarily eﬀects low energy modes. We
sp e c ulate that we can one day modify the vacuum modes distribution even at high energies (particularly at
some particle resonance or resonances if these exist) perhaps by means of strong ﬁelds.
Therefore in semiconductors, the response of an electron to a given force is quite diﬀerent from one material
to another. The “eﬀective mass” of an electron in silicon is larger than in gallium arsenide, for example.
Although not directly a ZPF-determined eﬀect, it nonetheless provides a cogent example as to how particle
masses can depend on environments to which they are strongly coupled. A similar eﬀect has recently been
reported for particles produced inside collis ions between heavy nuclei. Experimental evidence was reported
by Wurm for a change in the eﬀective mass of the ρ-mes on during a collision as reported by Schewe and
Stein (A.I.P. Bulletin No. 369). The bulletin also states: “According to Volker Koch o f Lawrence Berkeley
Laboratory, this eﬀect can take place for particles inside any nuclear environment, from the most commo n
atoms to superdense neutron stars.”
One of the ﬁrst objections typically raised against the e xistence of a real ZPF is that the mass equivalent
of the energy embodied in Eq. (1) would generate an enormous spacetime curvature that would shrink the
univer se to microscopic size. The resolution of this dilemma lies in the principle of equivalence. If inertia is an
electromagnetic phenomenon involving interactions between charge and the ZPF, then gravitation must be
a similar phenomenon. The mere existence of a Z PF would not necessarily generate g ravitation or spacetime
curvature. Indeed, pr e liminary development of a conjecture of Sakha rov (19 68) by Puthoﬀ (1989a) indicates
that the ZPF in and of itself cannot be a source of gravitation (see also discussion in Haisch a nd Rueda
Expressed in the simplest possible way, all matter at the level of quarks and electrons is driven to o scillate
(zitterbewegung in the terminology of Schr¨odinger) by the ZPF. But e very oscillating charge will generate its
own minute electromagnetic ﬁelds. Thus any particle w ill e x perience the ZPF as modiﬁed ever so slig htly
by the ﬁelds of adjacent particles. . . and that is gravitation! It is a kind of long-range van der Waals force.
Such a ZPF-based theo ry of gr avitation is only in the exploratory stage at this point. The Puthoﬀ (1989a)
analysis that resulted in the calculation of a proper Newtonian inverse-square law of attraction has since
been shown to be problematic, e .g. see Carlip (1993) and the reply by Puthoﬀ (1993), also Cole, Danley and
Rueda (19 98). Moreover a t this time there is no accounting for the gravitational deﬂectio n of light other
than to invoke a variable permittivity and permeability of the vacuum due to the presence of charged matter.
However if it can be shown that the dielectric properties of the vacuum can be suitably modiﬁed by matter
so as to bring about light deﬂection, this may be a viable alternative interpretation to spacetime curvature
since light propagation serves to deﬁne the metric.
A concept has been proposed that attempts to account for the inertia of matter as an electromagnetic reaction
force. A parallel gravitation concept along lines conjectured by Sakhar ov (1968) also exists in preliminary
form, and is consistent with the proposed origin of inertia as demanded by the principle of equivalence. On
the basis of this ZPF-inertia concept, we can deﬁnitively rule out o ne speculatively hypothesized propulsion
mechanis m: matter possessing negative inertial mass, a concept originated by Bondi (1957) is shown to be
logically impossible. One cannot “turn around” the reaction force an o bject experiences upon accelerating
into an oppositely directed ZPF momentum ﬂux. What you move into comes at you.
Is it proper to regard the ZPF as a real electromagnetic ﬁeld? The measurements by Lamore aux (1997) of the
Casimir force show exce llent agreement — at the ﬁve percent level (much better than previous experiments)
— with theoretical predictions. One interpretation of the Casimir force is that it represents the radiation
pressure resulting from the exclusion of certain ZPF modes in the cavity between the (uncharged) conducting
plates (Milonni, Cook and Goggin 1988). There a re alternate ways of look ing at this (cf. Milonni 1994).
We suggest that it is fruitful at this stage to continue exploring the ramiﬁcations of a real-ZPF paradigm
and that just as a real, measureable Casimir force results upon construction of an uncharged para llel-plate
condenser, so too does a real, measureable reaction force result upon acceleration thereby creating the inertial
properties of matter.
We acknowledge support of NASA contract NASW-5050 for this work. BH also acknowledges the hospitality
of Prof. J. Tr¨umper and the Max-Planck-Institut where some of these ideas originated during several
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