It is shown that the principle of conservation of energy implies
the existence of a relativistic effect that for any observer in
a non empty, homogeneous, stationary, nearly flat space the time
runs slower at the distance according to the formula
Because of the conservation of energy the photons have to experience some dynamical friction resulting in their redshift. If they didn't then in principle the matter could be carried away in photons and then returned in photons without any loss of energy. It would have caused a temporary change of gravitational field that could be used to create energy the same way as it is done in a tidal power plant but in this case the energy would be created from nothing. It wouldn't be possible in the world in which energy is conserved. It says that if energy is conserved the photons can't move around in a homogeneous, stationary space without any redshift and obviously there has to be a gravitational reason for it.
The reason can't be the mythical tired light effect (a redshift without a corresponding time dilation) since it is not possible in relativistic gravity where the whole physics is just the curvature of space (that is obviously causing no redshift) and the time dilation. So it has to be the time running slower at the source of light, the same as it is in the common gravitational redshift. However, unlike in the common gravitational redshift, where the redshift changes to the blueshift when the photon moves back by the same path, the effect of dynamical friction has to produce a redshift in any direction. Such a redshift is not possible in the Newtonian model of gravity with its conservative gravitational field so the effect must be a relativistic one and so the dynamical friction experienced by photons is, and is called here, relativistic dynamical friction. The physical reason for it (time running slower away from the observer and in any direction) is called here the general time dilation.
The implications of the existence of general time dilation
are that the light signals in presence of matter are not time
reversible and so the spacetime metric must contain
The general time dilation has been always considered negligible
and to the best knowledge of this author it is not included in
any contemporary cosmological theory (for obvious reasons in
none of those based on Riemannian geometry).
Possibly for this reason it has been never determined exactly or
at least its derivation is not placed neither in textbooks on
The tool that has been applied to do the calculations is
the Newtonian model.
It is possible to apply the Newtonian model
rigorously here since what is calculated is only the
gravitational energy gained by the
arbitrarily slow matter in an arbitrarily flat
space after the photons had passed by.
The trick is to investigate the imprint that the photons
have left on the slow matter and to conclude from this imprint
what must have happened to the photons in the real world.
This way the photons don't get directly into the
calculations and so the calculations comply with both rules
of correct application of Newtonian math: negligible
velocities and negligible curvature of space.
The "tired light effect", while not being a real effect,
can be simulated (in a form of dynamical friction),
similarly as other fictitious Newtonian entities (as e.g.
gravitational attractive force or gravitational
energy) are simulated without being related
physically to the real world.
Despite the lack of physical relation, their math, in a kind
of magical way (in fact by analogy between the Newtonian math
and the time dilation), produces arbitrarily accurate results
whenever the space is arbitrarily flat.
So whenever the physics assures that the Newtonian math is
accurate, the calculations are done using locally the
Newtonian magic, as it's done, even for cosmological
applications, by other
After the light has radiated out from its source, the space
between the source and the plane of photons is not isotropic
any more.
The state of gravitational equilibrium of each dust particle
between the plane at
Physically, what has changed between the source and the sheet of photons is that now there is a gradient of time rate that has changed the probabilities of finding dust particles at various points between the source and the sheet of photons. The calculations that would tell us about what happens based on those probabilities might be a nightmare. Fortunately we can avoid the horror of calculating probabilities by noticing that the rate of time in space is represented exactly by the Newtonian gravitational potential and so the Newtonian model can tell us exactly what happens. So in the magical world of Newtonian model each dust particle is pushed in the positive direction of the r axis as if the light dragged the particles behind itself. Each particle acquires Newtonian gravitational energy.
The acceleration at each dust particle expressed in terms of
Newtonian potential
![]() | (1) |
where G is Newtonian gravitational constant, and other terms
as described before. The gravitational energy acquired by an
element of space containing particles of mass dm is
![]() | (2) |
Because of the principle of conservation of energy this energy has to be equal energy lost by the light
![]() | (3) |
Taking second derivative with respect to r one gets from
equations (1), (2), and (3)
![]() | (4) |
This value of L makes it of course equal to the cosmological constant of Einstein's universe of mass density r. It is an interesting result since the derivation has been done using only the Newtonian magic.
Solving equation (4), selecting from the
solutions the one that corresponds to conditions of the
model, replacing mass of photons m(r) by their coordinate
frequency n(r) to which m(r) is
proportional, and replacing
| (5) |
| (6) |
The
| (7) |
![]() | (8) |
with spatial part of assumed curvature
It might be worth noting that, as follows from equ. (8), an isotropic spacetime might have a property that at any stationary observer the sum of curvature of space (1/R) and of the change in rate of proper time along the distance vanishes:
![]() | (8a) |
Equation (6) tells that the universe should look as if its apparent expansion were accelerating since the observed redshift from equation (6)
| (9) |
| (10) |
| (11) |
| (12) |
Another conclusion might be that the light radiating from a virialized cloud of dust (and possibly any other) must have redshift always greater than the gravitational redshift that is proper for that cloud and might be greater by many orders of magnitude. It is because the gravitational redshift of the light originating in the center of a cloud of dust and reaching its surface at distance r from the center is only
| (13) |
In a virialized cloud of dust the kinetic energy of the particles of dust acts as the isotropy of space in the model used for calculations, by effectively removing for the purpose of calculations the gravitational field and making the system stable, allowing this way the simple calculations leading to (9). As it is seen from comparing (9) and (13) the general time dilation in a virialized cloud of dust causes always greater redshift than gravitational redshift and how much greater depends only on the radius of the cloud (r) and its density (function of R).
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