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Questions and Answers

Questions and Answers about the Origin of Inertia and the
Zero-Point Field

NOTE -- This section
attempts to elucidate the possible connection between inertia and the
zero-point field and its implications via straightforward questions and
answers. This results in considerable oversimplification especially
since research to date has been limited to the assumptions of stochastic
electrodynamics. Our research colleagues are urged to base their
professional judgments not on these questions and answers, but rather on
the published
papers and the goal of CIPA to explore whether these concepts can be
reformulated and validated within the more comprehensive disciplines of
modern quantum field theory, string and brane theory, quantum gravity,
supersymmetry etc. The SED and ZPF perspective presented below must be
viewed as a potentially fruitful set of interrelated concepts bearing on
some foundational problems in physics, but concepts that remain to be
proven. The testing, examination and, if promising, development of these
concepts is the mission of CIPA.

What is the zero-point field or zero-point fluctuations
(ZPF)? What is its relationship to the quantum vacuum?
In the view of modern physics, the vacuum is far from
empty. Take away all particles and all electromagnetic radiation and you
will have an apparently empty region of space at a temperature of
absolute zero. But in fact this "vacuum" will still be full of energies
and particle pairs (such as positrons and electrons): the
electromagnetic zero-point field, the zero-point fields of the weak and
strong interactions, and the Dirac sea of negative energy particle
pairs. All of these energies and particles are collectively referred to
as the quantum vacuum (making the vacuum in reality a plenum). Our work
so far has involved only one component of the quantum vacuum: the
electromagnetic zero-point field or zero-point fluctuations.
(Henceforth, unless stated otherwise, ZPF refers only to the
electromagnetic ZPF.) The ZPF was a hypothesis put forward by Max Planck
in 1911, and was developed by him and Walther Nernst between 1911 and
1916. In 1947 the effect of the ZPF was directly demonstrated by Willis
Lamb, in a famous experiment, which Lamb himself has described as "a
proof that the vacuum does not exist" (i.e. that the "vacuum" is a
"plenum"). The Casimir effect, predicted in the following year and
subsequently verified, is another direct demonstration of the ZPF's
reality.

But where does the ZPF come from?

Imagine an oscillator, such as a pendulum.
Unless you keep putting in energy to keep it going, any swinging
pendulum will eventually come to rest as a result of friction. But
things are different in the quantum realm. The Heisenberg uncertainty
relation would forbid a quantum pendulum from ever coming completely to
rest. There is a minimum energy that you cannot take away according to
quantum laws. Like a pendulum, light and other forms of electromagnetic
radiation consist of oscillations: in this case oscillations of electric
and magnetic fields. Every direction, every frequency and each
polarization state of the electromagnetic field thus has a minimum
energy, thanks to the Heisenberg uncertainty relation. Add up all of
these "modes of the field" and you have the electromagnetic ZPF.

But wouldn't this argument yield an
infinite ZPF? Surely there has to be a cutoff somewhere.
At higher and higher energies the electromagnetic and the
weak interactions become the same electroweak interaction. At very high
frequencies (i.e. high energies) the ZPF therefore ceases to be a purely
electromagnetic field. Rather than a cutoff there would be a gradual
transition from a purely electromagnetic ZPF to an electroweak ZPF. At
even higher energies this would unify with a gluon-related zero-point
field. Indeed the governing equations become increasingly non-linear and
there is the likelihood that, just as with the Planck function, this
will lead to quenching of the divergence. Thus at higher and higher
energies the relevant physics changes and so it would be incorrect to
think (or worry) about infinite electromagnetic energy in the ZPF.
Collectively, however, when all fields are counted, the ensemble of
their vacua still presents a problem of divergence that needs to be
addressed.

Is the ZPF a kind of ether? Does it
violate special relativity?
No, not at all. The
ZPF as used in stochastic electrodynamics is nothing other than
electromagnetic waves, a form of light. This makes the ZPF by definition
consistent with special relativity, because special relativity is based
on light propagation. The frequency-cubed spectrum of the ZPF renders it
Lorentz invariant. Therefore it is nothing like the 19th century ether
concept.

Your article Beyond
E=mc2 is subtitled ``A First Glimpse of a Universe
Without Mass.'' But what does this mean? How can there be no mass?

A goal of modern quantum field theory is to
eliminate mass as a primary property of matter, so we are pursuing a
mainstream objective of contemporary physics. For example, it is
believed that the sum of the masses of the 3 quarks constituting protons
or neutrons is only 2 or 3 percent of the inertial mass of those protons
or neutrons. Most of the mass is attributed to the energy associated
with quark motions and gluon fields, but precisely how this energy
translates into the property of mass through a Higgs field is not easy
to understand (see two recent articles by F. Wilczek in Physics Today,
Nov. 1999 and Jan. 2000 for an overview). Our semi-classical approach is
quite different and at this point involves purely classical
electrodynamics plus a real electromagnetic ZPF that has exactly the
same energy density spectrum as the quantum electromagnetic ZPF. We have
found that when an object is forced to accelerate, it will see the ZPF
to be asymmetric, or in other words, distorted. Due to this distortion
the accelerating object will see a zero-point flux of energy and
momentum coming at it, whereas ordinarily, when the object is not being
accelerated, the ZPF is perfectly uniform and symmetric. A key result of
our analysis is that these fluxes prove to be proportional to the
acceleration of the object, i.e. the more rapid the acceleration, the
more the ZPF is distorted. Material objects consist of charged quarks
and electrons, which will tend to scatter any oncoming electromagnetic
flux. When all the quarks and electrons in an object scatter the
distorted ZPF passing through, the object will experience a kind of drag
force. We are proposing that this might be what the inertia reaction
force really is... the drag force due to being accelerated through the
vacuum fields. In this view, objects would not intrinsically resist
being accelerated; objects would not possess mass. Mass would really be
just a way of characterizing the resistance due to the ZPF molasses (or
in the future more general case, the quantum vacuum molasses) that kicks
in upon acceleration. Of course the limitation that we are only, so far,
considering the electromagnetic ZPF means that what we have found may be
only a part of the story. The electromagnetic ZPF may contribute to
inertia but still not account for all the mass.

[NOTE: In the Standard Model attempt to obtain, in John
Wheeler's quote, ``mass without mass,'' the issue of inertia appears to
be left out of the picture. As Wilsczek states: ``Most of the mass of
ordinary matter, for sure, is the pure energy of moving quarks and
gluons. The remainder, a quantitatively small but qualitatively crucial
remainder -- it includes the mass of electrons -- is all ascribed to the
confounding influence of a pervasive medium, the Higgs field
condensate.'' An explanation of proton and neutron masses in terms of
the energies of quark motions and gluon fields is fine, but falls short
of offering any insight on inertia itself. One is no closer to an
understanding of how this energy somehow acquires the property of
resistance to acceleration known as inertia. The modern Standard Model
explanation of mass is satisfied if it can balance the calculated
energies with the measured masses but merely equating energy and mass
does not explain inertia. The quantum vacuum-inertia hypothesis
addresses the deeper issue of what inertia might actually be, viz. a
force originating in quantum vacuum distortions that makes matter resist
acceleration.]

But if there is no mass, what
happens to the concepts of momentum and kinetic energy?
So long as an object is in uniform motion, its momentum
and kinetic energy are purely hypothetical, abstract properties. Indeed
their values depend on the relative motion of you and the object, and so
the momentum and kinetic energy you calculate for a moving object can
take on any value you like by changing your own motion. Real effects
only arise when you change the velocity of an object, such as when two
billiard balls collide. When you change the velocity, i.e. accelerate,
that is when the ZPF distortion appears and then forces arise which
behave like the inertia of mass. Momentum and kinetic energy of material
objects in motion are thus useful mathematical bookkeeping tools that
will tell you what to expect when you change velocity, such as in a
collision, but real measureable forces only arise when that change of
velocity occurs. Note that we do attribute momentum and energy to the
electromagnetic zero-point field. Indeed, the change in momentum of an
object in a collision can be attributed to the momentum flux of the ZPF.

What are the implications for
gravity? After all, the principle of equivalence dictates that inertial
mass and gravitational mass must be same.
General relativity (GR) attributes gravitation to
spacetime curvature. Modern attempts to reconcile quantum physics with
GR take a different approach, treating gravity as an exchange of
gravitons in flat spacetime (analagous to the treatment of
electromagnetism as exchange of virtual photons). A non-geometric (i.e.
flat spacetime) approach to gravity is legitimate in quantum gravity.
Similarly another non-geometric approach would be to assume that the
dielectric properties of space itself may change in the presence of
matter: this can be called the polarizable vacuum (PV) approach to
gravity. Propagation of light in the presence of matter would deviate
from straight lines due to variable refraction of space itself, and
other GR effects such as the slowing down of light (as judged by a
distant observer) in a gravitational potential would also occur. But of
course it is the propagation of light from which we infer that spacetime
is curved in the first place. This raises the interesting possibility
that GR may be successful and yet not because spacetime is really
curved: rather because the point-to-point changes in the dielectric
(refractive) properties of space in the presence of matter create the
illusion of geometrical curvature. A PV type of model does not directly
relate gravitation to the ZPF (or to the more general quantum vacuum)
but it does appear to provide a theoretical framework conducive to
developing the conjecture of Sakharov that it is changes in the ZPF that
create gravitational forces (although it also has the drawback of
apparently being at odds with the existence of black holes).

But isn't the energy density of the
ZPF so high that it would have an enormous gravitational effect, just
like a huge cosmological constant?
Not
necessarily. If gravitation derives from the ZPF (and possibly the other
quantum vacua) and changing dielectric properties of space, then the
energy of the ZPF cannot gravitate. Gravitation would consist of minute
changes in the ZPF in the presence of matter in analogy to the minute
changes in the ZPF that an accelerating particle experiences. Indeed,
one would be able to derive the principle of equivalence if we had a
complete quantum vacuum-based theory of inertia and gravitation
(including possibly the weak and strong interaction zero-point fields).
But certainly the ZPF would not act on itself to gravitate; that would
be impossible in this picture. The argument about a huge cosmological
constant arising if you take the ZPF literally misses the point that a
self-consistent ZPF basis for both inertia and gravitation would
necessarily preclude this.

Returning to inertial mass, how
could a neutral particle interact with the electromagnetic vacuum?
Wouldn't your theory predict neutral particles to be massless, and if
so, what about the recent neutrino mass determination?
The neutron would be no problem: it consists of 3 charged
quarks (the sum of electric charges cancelling) and the interactions
with the ZPF almost surely take place at the level of the individual
quarks. But if the neutrino is truly neutral, not consisting of any
smaller charged particles, then indeed the electromagnetic ZPF inertia
hypothesis could not yield a mass. But recall that there are two other
zero-point fields: those associated with the weak and strong
interactions. The neutrino is governed by the weak interaction, and it
is possible that a similar kind of ZPF-particle interaction creates
inertial mass for the neutrino but now involving the ZPF of the weak
interaction. At present this is pure conjecture. No theoretical work has
been done on this problem. (It is worth keeping in mind, though, that
while there is now considerable indirect evidence that neutrinos possess
mass, even the recent Super-Kamiokande measurements are not direct
measurements of neutrino mass.)

What does the quantum
vacuum-inertia hypothesis have to say about the mass in the
E=mc2 relationship?
The customary
intepretation is that one kind of thing, energy, can change into a
completely different kind of thing, mass, and vice versa... almost like
magic. The ZPF perspective offers a very different view, which is not of
course tantamount to proof. There is an extremely rapid particle quantum
fluctuation that can be attributed to the perturbations of the ZPF. This
was named Zitterbewegung (German for quivering motion) by Schroedinger,
and in a model proposed by Dirac the fluctuations of this Zitterbewegung
happen at the speed of light, c. In his 1989 attempt to develop the
Sakharov conjecture connecting the quantum vacuum and gravitation,
Puthoff suggested (as others had speculated previously as well) that the
kinetic energy associated with the ZPF-driven Zitterbewegung is what
provides the energy for the E=mc2 relation. The real stuff is
the energy, E, and as with inertial mass, it is only our (obstinate)
habit of believing that matter must possess mass that leads to our
insisting that there must exist a right hand side to this equation,
namely mc2. In reality (perhaps) there is no mass, just the
energy, E, that the quantum vacuum gives in the form of Zitterbewegung
in the same way that there is no inertial mass, just the force that the
quantum vacuum gives when an object accelerates. In a sense this does
away with the need for a veritably magical transmutation of energy into
matter or matter into energy. In this view we never get energy by
destroying matter. We get energy by liberating some or all of the
kinetic energy that the quantum vacuum puts into the Zitterbewegung of
what are really massless quarks and electrons. Rest mass would really be
ZPF energy (or more generally quantum vacuum energy) associated with a
particle via Zitterbewegung (almost certainly at a resonance). This
approach to rest mass is very suggestive, but of course needs a great
deal more work.

Doesn't General Relativity (GR)
already provide an origin for inertia?
Einstein
formulated GR by assuming that the force you feel standing still in a
gravitational field, say at the surface of the Earth, is
indistinguishable from the force you would feel if you were
accelerating, say in a rocket steadily increasing its speed at one gee.
(Actually this is only true for a point. Tidal effects can distinguish
acceleration from gravitation at other than a single point.) This is the
"principle of equivalence" and is tantamount to assuming that inertial
mass and gravitational mass are equal. The consequence of this is that
all objects fall at the same rate (an experiment attributed, perhaps
apocryphally, to Galileo at the Leaning Tower of Pisa). But note that
the principle of equivalence is an assumption, not an explanation.
Assuming that a one-gee gravitational force and a one-gee inertial force
are equal may be a true representation of reality, but is different from
explaining how the forces originate. The mathematical formulation of GR
represents spacetime as curved due to the presence of matter and is
called geometrodynamics because it explains the dynamics (motions) of
objects in terms of four-dimentional geometry. Here is a crucial point
that is not widely understood: Geometrodynamics merely tells you what
path (called a geodesic) that a freely moving object will follow. But if
you constrain an object to follow some different path (or not to move at
all) geometrodynamics does not tell you how or why a force arises.
Geometrodynamics leaves it up to the concept of inertia to generate such
a force. Logically you wind up having to assume that a force arises
because when you deviate from a geodesic you are accelerating, but that
is exactly what you are trying to explain in the first place: Why does a
force arise when you accelerate? Geometrodynamics explains the motion of
unconstrained objects, but has no mechanism to generate forces for
constrained objects. It leaves it to inertia to provide that force, but
this merely takes us in a logical full circle. For a more detailed
explanation of this see Dobyns, Rueda and Haisch (2000).

What is this new interpretation of
the de Broglie wavelength of a moving particle that you are proposing?

Our Poynting-vector approach to inertia (the
1998 Rueda and Haisch papers) strongly suggests that the interactions
between the ZPF and charged fundamental particles (quarks and electrons)
take place at specific frequencies or resonances. Consider the electron.
Where in frequency would such a resonance be? On reading articles by
Hunter, by Kracklauer and chapter 12 in the monograph by de la Pena and
Cetto, we discovered a very similar resonance concept, call it the de
Broglie resonance, that might explain the wave-like properties of a
moving particle. In the 1920's de Broglie proposed that just as a wave
of light can sometimes act like a particle (a photon) depending on the
measurement you make, so too can a particle sometimes behave like a
wave. He postulated that the wavelength of a moving particle would be
h/p, where h is Planck's constant and p the momentum. This was confirmed
for the electron in a famous 1927 experiment by Davisson and Germer. But
how does a particle acquire such wavelike attributes? This has remained
a fundamental mystery of quantum physics, and the usual reply is
effectively: "Don't ask such questions. It's just a law of nature." But
de Broglie made a second, less well known proposal. If you combine the
E=mc2 and the E=hf equations (where f is frequency), you can
calculate a frequency known as the Compton frequency. de Broglie
believed that this Compton frequency reflected, in the case of the
electron (quarks were not yet discovered), some kind of fundamental
intrinsic oscillation or circulation of charge associated with the
particle. However this presumed oscillation can also be interpreted
instead as being externally driven, where the external driving agent is
the ZPF (see chap. 12 of de la Pena and Cetto). Now comes a very
intriguing result. One can easily show that if the electron really does
oscillate at the Compton frequency in its own rest frame, when you view
the electron from a moving frame there is a beat frequency superimposed
on this oscillation due to the Doppler shift. It turns out that this
beat frequency proves to be exactly the de Broglie wavelength of a
moving electron. So our conjecture is that the resonance that is
involved in giving the electron inertia is the very same resonance as
the one that gives the electron its apparent wave properties when in
motion. It is a very appealing picture suggesting a connection not only
between electrodynamics and mass, but between electrodynamics and
quantum mechanics: the ZPF drives the electron to undergo some kind
oscillation at the Compton frequency and this is where and how the
inertia-generating interaction takes place and where and how the de
Broglie wavelength originates due to Doppler shifts (for details see Haisch and Rueda
(2000).