^{*}

It is pointed out that the inflationary flat Λ-CDM-model coming out from a big bang seems to be inconsistent. An alternative model based on previous work by the author is outlined. It starts with a geometrical phase transition in Minkowski space where the source of the gravitational field is a Higgs-like scalar field <i>φ</i>. After the phase transition space-time is a contracting anti-deSitter space. Matter and radiation are created over a very long period of about 30 billion years from the gravitational energy. About 44 billion years after the phase transition the universe runs through a nonsingular minimum.

In today’s cosmology the inflationary flat -CDMmodel coming out from a big bang (standard model) is widely accepted as the best model of our universe. Although in this model most observations are well matched there are nevertheless some serious problems.

Firstly: The big bang is out of physics and a source of some unsolved problems.

Secondly: The huge cosmological constant driving inflation must fall off within a tiny fraction of a second to the extremely small value we observe today where the inflaton field gives off its energy into reheating the matter. Up to now no consistent field theoretical model has been found to describe this process.

Thirdly: A positive cosmological constant according to may explain the small deviation of the redshift-versus-distance relation from that for. On the other hand such a constant leads to problems in galaxy clusters. As shown in ref. [

This leads to an additional force between two masses which increases linearly with the distance of the masses (repulsive for and attractive for). In refs.[1, 2] it has been shown that the masses and mean distances of galaxies in clusters have just such values that this additional force plays an important role. More precisely, in case of with which means the repulsive forces between the galaxies are so strong that the clusters could not exist unless the content of uniformly distributed cold dark matter is greater than five times the content in the standard model. This, however, would close the universe and lead to an age problem. In other words, the standard model seems to be not consistent.

Fourthly: The standard scenario of galaxy formation is based on the paradigm of cold dark matter. Cold dark matter goes lumpy rather rapidly, and the lumps attract the baryonic matter. Latest observations, however, show that galaxies with their first star population have existed already some hundred million years after the big bang, and it seems to be questionable whether the cold dark matter scenario can explain this. Moreover, up to now this kind of matter has not been found.

Finally: It is generally claimed that the peaks in the CMB correspond to acoustic oscillations in the photonbaryon plasma before recombination and that the positions of the peaks in the power spectrum favor definitively a flat universe. However, in ref.[

In recent years some efforts have been made to understand the big bang as a bouncing point of a cyclic universe. Ashtekar et al. [

The above problems are overcome in an ever oscillating universe without a singularity [2,6,7]. In this model the universe comes out from the Minkowski space by a geometrical phase transition in some distant past. This phase transition goes off in a Robertson-Walker spacetime where the source of the gravitational field is a real massless and selfinteracting minimally coupled scalar field with a potential

(see

The field equatons read

where a dot denotes the derivative with respect to, the prime in Equation (3c) the derivative with respect to the argument and a flat, closed and open space respectively.

At the very beginning the universe is in the wrong unstable vacuum with and. As shown in ref.[

The selfinteraction of the scalar field lets the spacetime go over spontaneoulsy into the true stable vacuum with and.

As shown in ref.[

and

Furthermore, the constants a and b can be expressed by the constants and so that the potential (2) reads

(see ref.[

As shown in ref.[

with

and

The purely gravitational energy density (7c) is due to Møllers energy-momentum complex [

Any phase transition involves spontaneous symmetry breaking. In the above geometrical phase transition the symmetry in the wrong vacuum is broken down to in the true vacuum, and the 10-parametric isometry of the Minkowski space is broken down to the 6-parametric isometry of the antideSitter space.

After the phase transition the anti-deSitter space starts to contract. However, this space-time can not be a model of our universe since it contains neither matter nor radiation. Hence, how did matter and radiation came into being?

In the contracting anti-deSitter space there is a natural energy source from which matter and radiation can be created. This source is the gravitational energy (7c) with which is positive as long as. In refs. [2, 7] a phenomenological model describing the creation of matter and radiation from this positive gravitational energy supply is presented. It is based on the fundamental law of energy conservation, that means that the sum of the gravitational energy density, the energy densities of created matter and radiation and the density of dark energy is constantly zero as after the phase transition, hence

The creation of matter (index) and radiation (index) is described by the two equations

with phenomenological creation functions and. The first terms on the right hand sides of these equations correspond to the conversation laws and respectively. In these equations matter means normal matter with non-vanishing rest mass and infinite lifetime (protons, electrons, neutrinos) and possibly cold dark matter. However, in the following we exclude cold dark matter (see Section 1 and the discussion of a universe without cold dark matter and with a negative cosmological constant in Subsection 2.4).

Equations (9) have been investigated in detail in refs.[2, 7] where in ref.[

the maximal scale factor of the anti-deSitter space is with the present day scale factor. Furthermore, the creation functions and become zero at. This can be interpreted as a smooth transition of the universe from the creation era to the conservation era at. And it seems to be obvious that this transition takes place when the gravitational energy density becomes zero, hence

according to Equations (7c) and (8). Thus the energy content of the universe is determined by the two fundamental constants and.

The period of the creation era is about 30 billion years, and in this extremely long time about one proton and one electron per cubic meter is created—an exceedingly small cross section!

After the creation era the universe with its energy content (11) contracts further, and the question arises if it ends in a big crunch. It does not. In ref.[

Recent investigations into the existence of a quarkgluon plasma (see ref.[

After the run through the minimum the universe expands and arrives after 44 billion years at its maximal extension because of the negative cosmological constant (10), then it contracts again, and so on: An open ever oscillating universe without a big bang.

Is this cosmological model in agreement with observations?

1) What about cold dark matter?

Cold dark matter plays in the standard model a threefold role. Firstly, it yields a mechanism of structure formation (see Section 1), secondly it is assumed to hold together the galaxies in clusters, and thirdly one assumes that cold dark halos around galaxies explain the flat rotation curves.

Firstly: In ref. [

Secondly: In refs. [1,2] it has been shown that the additional attractive forces due to a negative cosmological constant (10) can completely replace cold dark matter in galaxy clusters.

Thirdly: A negative cosmological constant instead of cold dark matter can not explain the flat rotation curves in galaxies. These curves might have their origin in a very large baryonic halo. Indeed, in clusters a hot intergalactic plasma is known with a mass about five times the mass of luminous matter in the galaxies [16,17]. Hence the individual galaxies in clusters might be surrounded by a very large baryonic halo with a mass about five times their luminous mass.

So, maybe cold dark matter is not needed.

2) What about a negative cosmological constant?

Firstly: At first sight such a constant seems to contradict the observed small deviation of the redshiftversus-distance relation from that for. However, for a present day density (purely baronic) and a Hubble parameter the redshift-versus-distance relation does for not deviate from that for, at least up to. Hence, if an alternative explanation for the deviation can be given in case of this explanation holds also in case of the cosmological constant (10). Up to now two explanations are possible: Evolution effects of the observed SNIasupernovae (see for example refs. [18,19]) and a very small amount of absorbing intercluster gas and dust. Maybe both effects combine.

Secondly: A negative cosmological constant could lead to an age problem. This, however, is not true. With the above cosmological parameters and a cosmological constant (10) one finds which is in agreement with the age of the oldest globular clusters according to the scenario of galaxy formation proposed in ref. [

3) What about the origin of the small anisotropies in the CMB?

The run through the minimum is a giant collaps: As shown in ref. [

This, however, is only a qualitative picture which requires a quantitative analysis. Explaining the anisotropies in the CMB by classical shock waves instead of by quantum oscillations in an inflationary universe opens a new field in cosmology. A quantitative analysis of this new explanation is still to be found. However, if it comes true that the standard model is not consistent, an alternative model of our universe must be found, perhaps the model outlined in this article. And then shock waves in the bouncing point as an origin of the anisotropies in the CMB become important.

4) What about the nucleosynthesis?

The scenario represented in ref.[

5) The model gives answers to some fundamental questions in cosmology.

Firstly: The universe is so isotropic because after the phase transition in Minkowski space the anti-deSitter space (protouniverse) with its gravitational energy density is completely isotropic. Matter and radiation are created from the positive content of the gravitational energy over an extremely long time of about 30 billion years. About 44 billion years after the phase transition the universe runs through a minimum without a singularity. So there is no horizon problem.

Secondly: The geometry of the universe is uniquely determined by the phase transition. The universe is open.

Thirdly: The extreme smallness of is because of the reason why the universe is so big and so old.

Finally: The cosmological constant appears in a new light. It is an independent natural constant like and plays a threefold role:

a) and determine the potential (Equation (6))

b) determines the extension of the proto-universe (Equation (5)).

c) and determine the energy content of matter and radiation in the universe (Equation (11)).

These are satisfying answers. Nevertheless, it should be noted that an explanation of the structure of the CMB, especially its scale invariance, is still to be found. Explaining this structure is a strong advantage of the inflationary standard model.

As any other cosmological model also the model outlined in this article raises some (new) problems.

Firstly: Similar to the inflaton field in the theory of inflation the origin of the scalar field with its potential (2) is unclear. There is, however, a difference. The inflaton field is assumed to be created in the infinite temperature of the big bang, whereas the scalar field lies “sleeping” in its wrong vacuum state in the zero temperature Minkowski space. Anyway, in both cases the origin of the fields is a problem.

Secondly: How does the geometrical phase transition go off? Does it go off homogeneously (phase transition of second order) or inhomogeneously propagating from one or several seed regions (phase transition of first order)? In the first case we have one open universe, but a problem with causality since the space is infinite. In the second case we might have several finite but very huge bubbles of open universes with “Minkowski edge regions”, each separated from the other by space-like distances.

Thirdly: Can the phenomenological model (9) describing the creation of matter and radiation be derived from a quantum field theory of gravitation, matter and radiation in an anti-deSitter space? Unfortunately such a unified quantum field theory is a long way away.

Finally: Can the observed anisotropies in the CMB be derived from shock waves in the bouncing point?