The text below contains my findings which may be of interest to
people who have inquisitive minds and want to discover how Nature
really works. (This text is taken from my book "Foundational Flaws
in Modern Physics", which can be found at [Only registered users see links. ])

CONCLUSIONS

As is explained in §5.8 ([Only registered users see links. ]) and in
§2.1.3 ([Only registered users see links. ]), modern experiments
leave no doubt that the scalar potential is the most fundamental
concept describing gravitational fields.
Einstein introduced tensors because they made his equations
covariant. As J. D. North pointed out, "...Einstein sought to
preserve the tensorial nature of his field law in order to preserve its
general covariance" (North: [R#1] p.87). Tensors have this property
due to the fact that their components are vectors. However, due to
the same property of tensors, predictions of gravitational retardation
of clocks in cases where more than one field is acting are incorrect.
So we can no longer claim that gravitational fields are of tensorial
character. Obviously, experimental evidence for this was not
available in Einstein's times.
Moreover, as is pointed out in my book in section 2.1
([Only registered users see links. ]), it seems that Einstein didn't
believe that gravitational fields can really be made disappear by
transforming them away, as many modern relativists seem to believe.
It looks that for Einstein - tensors were just convenient technical
tools for the covariant and phenomenological description of
gravitational fields. As was already mentioned, Einstein didn't
introduce them because of evidence indicating that gravitational fields
are tensor fields. Concerning the history of introduction of tensors
by Einstein - John Stachel, who is no doubt an expert on the history
of Einstein's theories, wrote that
In trying to trace Einstein's journey from the special to the
general theory, the fol- lowing difficulty presents itself. In the
papers up to and including those published in 1912, there is no
mention of the need for a nonflat spacetime, much less of the
metric tensor as mathematical representation of the gravitational
field. Yet the first paper of 1913 presents us with a
full-fledged argument for the representation of the gravitational
field by g_mu_nu together with the development of
four-dimensional tensor analysis on a Riemannian manifold, the
Riemann tensor, etc.
(Stachel: [R#2] p.56)
Everything seems to indicate that it was only the mathematical
necessity which motivated Einstein to use tensors and the
four-dimensional tensor analysis on a Riemannian manifold.
Moreover, Einstein employed the four-dimensional tensors as
mathematical representations of gravitational fields in his
phenomenological theory. This fact seems to have escaped notice of
most physicists and they understood these four-dimensional
representations or descriptions as explanations. Soon some started
claiming, as Cornelius Lanczos, that "If we understand the proper
geometrical structure of the world, we also understand its physical
structure, because: physics is geometry" (Lanczos: [R#3] p.95).
As is pointed out in §1.3.6 ([Only registered users see links. ]),
Einstein made clear that this was not his understanding of general
relativity; but, unfortunately, it did not help much. The commonly
used geometric visualizations made an impression that they actually
are four-dimensional explanations of the processes and interactions of
Nature. Due to this confusion Einstein's principle theories were taken
as explanatory theories - even though Einstein never claimed that they
were. Einstein's point of view has been ignored and the
phenomenological descriptions are now considered as explanations.
Moreover, we consider these descriptions and the concepts which they
use as real objects, in other words as observables.
In his book - The Creation of Matter - Harald Fritzsch wrote that
The scientific method of exploration concerns the creation of
appropriate concepts to describe natural phenomena and the
establishment of connections between these phenomena. We feel
our way along this "road of ideas," along chains of causality.
We open up reality by attempting to construct a logical "road
network" free of contradictions, one which we then clap on to
reality. I have cautioned the reader against confusing the
network of scientific concepts - our picture of reality - with the
real world. Many of the mistakes and much of the tragically
flawed reasoning of our time are based on just this fallacy.
(Fritzsch: [R#4] p.276)
Indeed this confusion of our picture of reality with the real world is
what has happened in the case of Einstein's theories. This has
happened because we did not 'feel our way along this "road of
ideas," along chains of causality.' Ignoring causality considerations
and relying on mathematics as a primary guide - is the biggest
problem of modern physics.

It is correct to say that a body gets hotter when its temperature
gets higher. But will the temperature of a cold apple rise - when
we lift the apple? No, because the value of the temperature has
nothing to do with height. We may draw graphs on which time is
depicted graphically as a dimension, but this will not make time a
dimension. Geometry is part of mathematics and it can and needs to
be used in physics, but it is not physics as some seem to imagine.
We may use non-Euclidean geometry, but we cannot say that this
geometry is responsible for light being bent; geometry provides only a
description and not a cause or an explanation of why things happen.
As we've seen geometry cannot explain why the time delay of light
(see §4.5 [Only registered users see links. ]) and the clock
retardation take place and, therefore, it cannot be considered as an
explanation of gravitational effects.
It is clear from the article of D. M. Greenberger and A. W.
Overhauser that spacetime geometry is inadequate for describing or
predicting the outcome of their experiment. In fact, as they noted,
"...it turns out that the result of the COW experiment is
incompatible with the geometrical, weak equivalence principle..."
(Greenberger & Overhauser: [R#5] p.74). Yet, this is ignored by
adherents of constructively interpreted general relativity.
As G. Z. Adunas with his colleagues wrote: "However, there is
more than one aspect of quantum mechanical structure that requires a
deeper study in the context of gravity. This has been made
abundantly clear in recent years" (Adunas et al.: [R#6] p.192-3).
One must agree with this. And let's hope that this study is not only
"deeper" but also without preconceptions; because only then we can
learn what gravity really is.
As is pointed out in §4.3 ([Only registered users see links. ]),
in the period from 1928 to 1932 - Einstein was busy working on
theories of gravitation in flat spacetime. This of course means that
he did not believe that the spacetime curvature explained gravitation.
And he was right; it does not. As is demonstrated in §4.2
([Only registered users see links. ]), the assumption - that the
gravitational clock retardation is caused or explained by spacetime
curvature - leads to incorrect predictions. As is pointed out in §4.5
([Only registered users see links. ]), the results of the time delay of
light experiments can't be explained by spacetime curvature. In fact,
these experiments prove that properties of space are affected by
gravitational fields. But when we take this fact into account, we are
compelled to conclude that the observed bending of light proves that
space is not curved (as is explained in more details in section 4.4 [Only registered users see links. ]). As is pointed out in §4.6
([Only registered users see links. ]), the belief - that spacetime
curvature explains gravitational attraction - is incorrect. As is
explained in chapter 3, the assumption - that time is the fourth
dimension - leads to contradictions with evidence and paradoxes.
Hence, spacetime can only be considered as a mathematical concept.

Einstein's Equivalence Principle (EP) has led to many discoveries
(like gravitational redshift, etc.). So there is no doubt that it has
contributed to the progress of physics. But because we have failed
to appreciate that EP is only a part of a phenomenological theory -
it led us to erroneous understanding of gravitation. Our
misconceptions, which resulted mainly due to interpreting EP
constructively, are of fundamental importance. We not only did not
understand the difference between the effects of gravitation and effects
of motion, but we did not even suspect that there was any. We
thought that gravitational red-shift was a velocity effect and we did
not even suspect that this is actually a quantum/gravity effect. Due
to the Equivalence Principle (EP) and in conjunction with ignoring
causality considerations, we very often consider coordinate effects as
physical effects and vice versa. In any case, it is evident from our
previous discussions that EP cannot help us in developing a
constructive unified theory. Its main tenet, that for a freely falling
observer gravity doesn't exist, is only about phenomenology and not
about how Nature works. As Albrecht Fölsing reported:
More generally, Einstein did not approve of Heisenberg's talking
about "what one knows about nature, instead of what nature
really does. The physical sciences can only concern themselves
with what nature really does."
(Fölsing: [R#7] p.581)
We must agree with Einstein on this. From a multitude of
experiments, we know what Nature does in free fall. Physics must
concern itself with these phenomena. We must stop claiming, that
some effects don't take place, if the only basis for it is "what one
knows about nature" - in cases in which one's abilities to know are
restricted. This way, we disregard how Nature works and base our
considerations only on one's knowledge of something which one is
prevented from knowing; and this is nonsense. Let us realize that
EP is not about "what nature really does".
So even though EP was once inspiring and helpful, right now it only
confuses people. It implies that there is equivalence between
coordinate and physical effects, between effects of gravitation and
effects of motion, etc. - but modern experimental evidence disproves
this.
The fact that EP is not a law of Nature - tells us that there is no
relativity of acceleration; which means that the general relativity
principle is untenable.

More and more people realize that, in the quest for unified physics,
we must try to get rid of our preconceptions and prejudices. As
Roland Omn|1es wrote:
During the conception stage, the method is free to consider all
hypotheses, even the most far-fetched, in order to mimic Reality.
Everything can be tried, a bold abstraction of something that
has succeeded elsewhere, the exploration of the faintest clue...
(Omn|1es: [R#8] p.268)
It is sad to say but in the case of "the exploration of the faintest
clue", we seem to fail miserably. We not only missed many of the
clues which can tell us something about the future unified physics,
but we sometimes seem to be trying to make these clues invisible for
future physicists. Take for example the case of photons climbing up
or going down in a gravitational field. Many physicist seem to imply
that it makes no difference whether the energy and frequency of
these photons changes or not. But if we take into consideration
what was discussed in §5.5 ([Only registered users see links. ]),
this would also have to mean that it makes no difference whether a
particle falling in a gravitational field gains energy from the field or
not. What kind of physics is this?
On one hand, to make the rest masses of bodies independent of the
gravitational potential, we would have to assume that their gain in
kinetic energy comes from the gravitational field which accelerates
them. However, this leads to the conclusion that a free-falling
particle (or a photon) gains infinite energy when it falls into a black
hole. And this is in contradiction to the conservation laws.
On the other hand, if one admits the variability of rest mass
(depending on gravitational potential) - the energy transfer and
gravitons are not needed. The problem is that the concept of
gravitational potential, as necessary for the description of natural
phenomena, does not fit well to GR. As Max Born wrote: "...the
Newtonian notion of potential energy is alien to Einstein's theory..."
(Born: [R#9] p.354).
However, as has been pointed out in chapter 5, without the use of
gravitational potential energy - it is impossible to explain some
evidence which involves gravitational phenomena. And as was
mentioned above, the assumption of the independence of rest masses
from gravitational potential leads to contradictions with the laws of
conservation of energy and momentum.
We must also realize that the explanation of gravitational attraction
as an action mediated by gravitons - is untenable. It is in
contradiction with the conservation laws, as is explained on p.87
([Only registered users see links. ]) and 88.
Moreover, it is time to stop implying that inertia of bodies originates
from other masses. If this were the case - inertia of a body would
be increasing as it approaches other bodies. Hence, we would have
to assume that either the mass-energy of this body is not proportional
to its inertia, or that the law of conservation of energy is contradicted.
As was explained in §2.3.4 ([Only registered users see links. ]),
the assumption - that inertial effects arise as a result of forces induced
by apparently accelerating masses of the universe - is also untenable.
We must finally realize that general relativity is only a
phenomenological theory and that its applicability and validity have
limits.

As was pointed out, the causal effects of motion (which we observe)
prove that there is some background space; no matter how it
originates, or how we call it: space, background, field, ether or
whatever else. Moreover, this background space has physical
properties; and as we know, it's these properties which dictate the
speed of light. From the change of the speed of light we know that
these properties are affected by the presence of mass-energy. And
it's not only matter which affects space properties. As we discussed,
change of these properties in turn affects matter: it results in the
change of rest masses of particles. Hence it seems that properties of
space also have a say about how much energy is needed to create a
given particle. The electrostatic field of a charged particle contains
energy, which constitutes part of the mass of the particle. How can
the energy of the field of an invariant charge be changed? As far as
we know this can happen only when index of refraction of space,
where the charge is, is changed. This also implies the variable
coordinate speed of light; which is mentioned above. And this leads
to the explanation of the bending of light and the time delay of light
experiments. Change of index of refraction of space must affect
resonant frequencies of EM antennas and also resonant frequencies of
atoms and molecules, which we observe and call the gravitational
redshift (or clock retardation). And properties of space affect not
only the coordinate speed of light but also coordinate speeds of
matter waves. This explains why Newton's theory, which did not take
this into account, was not able to precisely predict the motion of rays
of light or of Mercury. So - as is evident - appreciating that space
has physical properties leads to explanations of many phenomena.
Even if the origin of this background space could be questioned, its
existence is evident and undeniable. I do not believe that we can
ever understand how Nature works, if we don't acknowledge the
existence of space as a physically and causally active entity.
Imagine a man who believes that the air has no weight, because
otherwise it would drop down. Do you think that such a man can
figure out why a balloon stays up in the air? He may come up with
some theories or hypotheses but can anyone of them really help him
understand why the balloon hovers above in the sky?
As we know if one added more (imaginary) epicycles to Ptolemy's
system, it would become more accurate in predicting the positions of
planets and other celestial bodies. But would it help us understand
better how gravitation works? I don't think so. Ptolemy's system
was also progress at some point in history; it allowed predictions of
positions of heavenly bodies. Evidently, the ability to make
predictions is not everything and it does not prove that the concepts,
which a given theory uses for making these predictions, represent
physical reality.
Richard P. Feynman wrote that
There was a time when the newspapers said that only twelve
men understood the theory of relativity. I do not believe there
ever was such a time. There might have been a time when
only one man did, because he was the only guy who caught on,
before he wrote his paper. But after people read the paper a
lot of people understood the theory of relativity in some way or
other, certainly more than twelve. On the other hand, I think
I can safely say that nobody understands quantum mechanics.
(Feynman: [R#10] p.129)
It is time to stop putting up with understanding relativity "in some
way or other". As we have seen, the misunderstanding of special
relativity led to adopting a point particle model of elementary
particles in quantum electrodynamics and then in quantum field
theory. In result structures of particles are not studied. It is also
due to our misunderstanding of relativity that properties of space are
not investigated and not taken into consideration. This in turn
makes it impossible for us to understand quantum properties of matter
and quantum effects in general.
Clearly, if we really want to ever understand quantum mechanics,
we need to understand Einstein's relativity properly (in Einstein's
way). We must realize that it is a principle theory and not a
constructive one; which means that it is not an explanatory theory
(see §1.2.1 [Only registered users see links. ]). It can't explain
such physical effects of motion as the retardation of moving clocks.
It can't explain inertial effects. And it cannot explain the value of
the speed of light. The above phenomena can be explained only by
a theory in which space is considered as a physical entity with
properties, but such space cannot be incorporated into Einstein's
theory. So his relativity theory can never be changed into a
constructive/explanatory theory.
To explain the above mentioned phenomena, we need a theory like
that of Lorentz and Poincaré. The relativity principle (RP) for that
theory was enunciated by Poincaré in 1904. It had different
interpretation than Einstein's relativity principle. Moreover, as
Charles Scribner, Jr noted:
Poincaré's adoption of the principle of relativity seems now to
have been provisional or incomplete in three respects.
First, although Poincaré was ready to postulate the exact
validity of the principle with respect to all physical laws, he was
troubled by the possible exception presented by gravitational
phenomena.
(Scribner: [R#11] p.675)
As is explained in §1.12.4 ([Only registered users see links. ]),
gravitation indeed defies the relativity principle (RP). So RP can't be
considered as a general law of Nature, as it has been up to now.
And although one could say that within the realm of special relativity
- relative motion is the only meaningful motion, we must realize that
we cannot say that this is true in physics in general. This only
appears to be true due to compensatory effects; exactly as Poincaré
hypothesized. However, this appears to be true - only when
gravitational effects are not involved.

In his book, Superstrings and the Search for the Theory of
Everything, F. David Peat wrote that: "The time may have come for
physics to ask some deep questions, for concealed in one of these may
well be the theory of the twenty-first century" (Peat: [R#12] p.338).
Indeed the state of physics of the twenty-first century depends on
whether we want to seriously ask ourselves:
Is our reality really four-dimensional?
Is time really a dimension?
Is space just an empty void without properties?
Are there no dynamical/causal effects of motion?
Are elementary particles dimensionless and structureless points?
Is a static field just a hail of points or degrees of freedom
endlessly emitted by its source?

As has been shown in this book, experimental evidence indicates that
the above questions must be answered in the negative. However,
this means that we have to radically change the way we view,
understand and interpret reality. And we don't need a new Einstein
this time. We only need to have a sober and unprejudiced look at
all experimental evidence. Some of us may be afraid of changes and
prefer status quo. But the changes in our understanding of reality
will take place sooner or later (even if many choose to hide their
head in the sand). The only question is: When will this happen?
The answer to this last question does not depend on me, it depends
on you dear reader. It is believed by many prominent physicists
that a new revolution in physics is coming. My hope is that by
bringing these questions and issues to your attention - I helped you
realise what kind of revolution it's going to be. I also hope that this
in turn helps you to take part in this revolution.

REFERENCES:
[R#1] J. D. North - "The Measure of the Universe - A History of
Modern Cosmology" - Clarendon Press - Oxford - 1965.
[R#2] Editors: Don Howard and John Stachel - "Einstein and the
History of General Relativity" - Birkh|auser - Boston · Basel ·
Berlin - 1989.
[R#3] Cornelius Lanczos - "The Einstein Decade (1905 - 1915)" - Elek
Science - London - 1974.
[R#4] Harald Fritzsch - "The Creation of Matter" - Basic Books,
Inc., Publishers - New York - 1984.
[R#5] Daniel M. Greenberger and Albert W. Overhauser - "The Role
of Gravity in Quantum Theory" - Scientific American 242, May
(1980), p. 66.
[R#6] G. Z. Adunas, E. Rodriguez-Milla, and D. V. Ahluwalia -
"Probing Quantum Violations of the Equivalence Principle" -
General Relativity and Gravitation Vol. 33 No. 2, 2001, p.183.
[R#7] Albrecht Fölsing - "Albert Einstein" - Viking Penguin, a division
of Penguin Books USA Inc. - 1997.
[R#8] Roland Omn|1es - "Quantum Philosophy" - Princeton University
Press - Princeton, New Jersey - 1999.
[R#9] Max Born - "Einstein's Theory of Relativity" - Dover
Publications, Inc. - New York, NY - 1965.
[R#10] Richard P. Feynman - "The Character of Physical Law"" -
MIT Press - Cambridge, MA - 1967.
[R#11] Charles Scribner, Jr. - "Henri Poincaré and the Principle of
Relativity" - American Journal of Physics 32 (1964), p. 672.
[R#12] F. David Peat - "Superstrings and the Search for the Theory
of Everything" - Contemporary Books - Chicago · New York -
1988.