New type of dark energy could solve Universe expansion mystery

Nature ◽  
2021 ◽  
Vol 597 (7877) ◽  
pp. 460-461
Author(s):  
Davide Castelvecchi
Keyword(s):  
Dark Energy ◽  
Universe Expansion ◽  
New Type

scholarly journals The Constant of the Universe Expansion Acceleration ΓH, the Einstein Variation of c and Parameters VH, Ω, Ʌ and ɣ

2020 ◽  
Vol 12 (3) ◽  
pp. 28
Author(s):  
J. G. Lartigue
Keyword(s):  
Dark Energy ◽  
Gravitational Field ◽  
Additional Condition ◽  
Expansion Velocity ◽  
Gravitational Acceleration ◽  
Universe Expansion ◽  
Physical Universe ◽  
C Value ◽  
Space Expansion ◽  
The Universe

The Hubble-Lemaitre equation v=H∙r  (cm∙s-1) represented a linear function of the radial Space expansion velocity, if H would be a constant. Sometimes it has been assumed as H = 1/t, which sends back to the classical v = r/t. However, the later discovered acceleration required the additional condition for H to be, also, a function of time; or, opposed, the existence of a not yet defined dark energy. In a previous paper [1] it had been proposed a provisional expression for a constant Universe expansion acceleration as function of distance: Γ= H2( cm∙s-2). Now, the substitution of r as a function of time, takes to five new equations of H, the Hubble velocity vH , the Hubble acceleration ΓH and the positive Hubble potential VH of the Space. So the proposed Hubble functions for the Space: H, rH , vH, ΓH and VH result higher than those in a gravitational field. All of these Hubble functions act in the total Space expansion though, into the Physical Universe, ΓH is not perceived as it does, continuously, the opposed gravitational acceleration g. Otherwise, a revision is made of the Einstein equation for the c value as function of the gravitational potential φ. Additional proposals are made about the horizons definitions and parameters Ω, Ʌ and ɣ.

scholarly journals The Energy Conservation in Our Universe and the Pressureless Dark Energy

2015 ◽  
Vol 2015 ◽  
pp. 1-4
Author(s):  
Man Ho Chan
Keyword(s):  
Dark Energy ◽  
Energy Conservation ◽  
Total Energy ◽  
Dark Energy Model ◽  
Vacuum Energy ◽  
Energy Model ◽  
Universe Expansion ◽  
The Law ◽  
The Universe

Recent observations confirm that a certain amount of unknown dark energy exists in our universe so that the current expansion of our universe is accelerating. It is commonly believed that the pressure of the dark energy is negative and the density of the dark energy is almost a constant throughout the universe expansion. In this paper, we show that the law of energy conservation in our universe has to be modified because more vacuum energy is gained due to the universe expansion. As a result, the pressure of dark energy would be zero if the total energy of our universe is increasing. This pressureless dark energy model basically agrees with the current observational results.

scholarly journals DARK ENERGY, DARK MATTER AND FERMION FAMILIES IN THE TWO MEASURES THEORY

2004 ◽  
Vol 19 (31) ◽  
pp. 5325-5332 ◽  
Author(s):  
E. I. GUENDELMAN ◽  
A. B. KAGANOVICH
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Coupling Constants ◽  
Fine Tuning ◽  
Electron Mass ◽  
Total Energy Density ◽  
Fermion Fields ◽  
New Type ◽  
The Universe

A field theory is proposed where the regular fermionic matter and the dark fermionic matter are different states of the same "primordial" fermion fields. In regime of the fermion densities typical for normal particle physics, each of the primordial fermions splits into three generations identified with regular fermions. In a simple model, this fermion families birth effect is accompanied with the right lepton numbers conservation laws. It is possible to fit the muon to electron mass ratio without fine tuning of the Yukawa coupling constants. When fermion energy density becomes comparable with dark energy density, the theory allows new type of states - Cosmo-Low Energy Physics (CLEP) states. Neutrinos in CLEP state can be both a good candidate for dark matter and responsible for a new type of dark energy. In the latter case the total energy density of the universe is less than it would be in the universe free of fermionic matter at all. The (quintessence) scalar field is coupled to dark matter but its coupling to regular fermionic matter appears to be extremely suppressed.

scholarly journals Holographic dark energy and the universe expansion acceleration

2006 ◽  
Vol 636 (2) ◽  
pp. 75-79 ◽  
Author(s):  
J.P. Beltrán Almeida ◽  
J.G. Pereira
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Universe Expansion ◽  
The Universe

scholarly journals A note on the relations between thermodynamics, energy definitions and Friedmann equations

2017 ◽  
Vol 32 (13) ◽  
pp. 1750078 ◽  
Author(s):  
H. Moradpour ◽  
Rafael C. Nunes ◽  
Everton M. C. Abreu ◽  
Jorge Ananias Neto
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Perfect Fluid ◽  
Observational Constraints ◽  
Pressure Equation ◽  
Universe Expansion ◽  
Friedmann Equations ◽  
Suitable Solution ◽  
Thermodynamic Pressure ◽  
The Universe

We investigate the relation between the Friedmann and thermodynamic pressure equations, through solving the Friedmann and thermodynamic pressure equations simultaneously. Our investigation shows that a perfect fluid, as a suitable solution for the Friedmann equations leading to the standard modeling of the universe expansion history, cannot simultaneously satisfy the thermodynamic pressure equation and those of Friedmann. Moreover, we consider various energy definitions, such as the Komar mass, and solve the Friedmann and thermodynamic pressure equations simultaneously to get some models for dark energy fluids. The cosmological consequences of obtained solutions are also addressed. Our results indicate that some of obtained solutions may unify the dominated fluid in both the primary inflationary and current accelerating eras into one model. In addition, by taking into account a cosmic fluid of a known equation of state (EoS), and combining it with the Friedmann and thermodynamic pressure equations, we obtain the corresponding energy of these cosmic fluids and face their limitations. Finally, we point out the cosmological features of this cosmic fluid and also study its observational constraints.

Constraining a New Type of Dark Energy Model from Present Observations

2013 ◽  
Vol 59 (2) ◽  
pp. 249-252 ◽  
Author(s):  
Xie Lei ◽  
Chen Jing-Jing ◽  
Zheng Wei-Wei ◽  
Xia Jun ◽  
Liu Gao-Ping ◽  
...  
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
New Type

scholarly journals Cosmological Model with Interconnection between Dark Energy and Matter

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 412
Author(s):  
Gennady S. Bisnovatyi-Kogan
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Density Ratio ◽  
Hubble Constant ◽  
Variable Component ◽  
Time Interval ◽  
Universe Expansion ◽  
The Difference ◽  
Cmb Fluctuations ◽  
The Universe

It is accepted in the present cosmology model that the scalar field, which is responsible for the inflation stage in the early universe, transforms completely into matter, and the accelerated universe expansion is presently governed by dark energy (DE), whose origin is not connected with the inflationary scalar field. We suppose here that dark matter (DM) has a common origin with a small variable component of dark energy (DEV). We suggest that DE may presently have two components, one of which is the Einstein constant Λ, and another, smaller component DEV (ΛV) comes from the remnants of the scalar field responsible for inflation, which gave birth to the origin of presently existing matter. In this note we consider only the stages of the universe expansion after recombination, z≃1100, when DM was the most abundant component of the matter, therefore we suggest for simplicity that a connection exists between DM and DEV so that the ratio of their densities remains constant over all the stages after recombination, ρDM=αρDEV, with a constant α. One of the problems revealed recently in cosmology is a so-called Hubble tension (HT), which is the difference between values of the present Hubble constant, measured by observation of the universe at redshift z≲1, and by observations of a distant universe with CMB fluctuations originated at z∼1100. In this paper we suggest that this discrepancy may be explained by deviation of the cosmological expansion from a standard Lambda-CDM model of a flat universe, due to the action of an additional variable component DEV. Taking into account the influence of DEV on the universe’s expansion, we find the value of α that could remove the HT problem. In order to maintain the almost constant DEV/DM energy density ratio during the time interval at z<1100, we suggest the existence of a wide mass DM particle distribution.

scholarly journals Harnessing Dark Energy in Five-dimensional Brans-Dicke Universe

2021 ◽  
Vol 31 (3) ◽  
Author(s):  
Kangujam Priyokumar Singh ◽  
Koijam Manihar Singh
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Accelerated Expansion ◽  
Fifth Dimension ◽  
Big Rip ◽  
Expansion Of The Universe ◽  
New Type ◽  
The Universe ◽  
Accepted Form

In trying to explain the present accelerated expansion of the universe in the light of a five-dimensional Brans-Dicke theory, it is found that the fifth dimension itself here acts as a source of dark energy. It may be taken as a curvature-induced form of dark energy, in one case of which it behaves similar to that form of dark energy arising out of the cosmological constant which is the most commonly accepted form of dark energy. It is also found that this new type of dark energy is free from big rip singularity and may be taken as a viable form of dark energy which can explain some of physical mysteries of the universe.

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