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December 2023
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137 Reads
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3 Citations
We show that by allowing our Universe to merge with other universes one is lead to modified Friedmann equations that explain the present accelerated expansion of our Universe without the need of a cosmological constant.
August 2023
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5 Reads
We show that by allowing our Universe to merge with other universes one is lead to modified Friedmann equations that explain the present accelerated expansion of our Universe without the need of a cosmological constant.
August 2023
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15 Reads
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3 Citations
Modern Physics Letters A
In this paper, we have suggested that the late time expansion of the Universe is caused by the absorption of baby universes. This absorption leads to a modified Friedmann equation with one free parameter B replacing the cosmological constant. The late time cosmology is modified in such a way that one can obtain agreement with the measured values of the Hubble parameter H(z) for z between 0 and the value corresponding to the time of last scattering of CMB for a suitable choice of B. In this paper, we show that the modified Friedmann equation with this choice of B also describes well other aspects of the large-scale structure of the Universe.
May 2023
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2 Reads
December 2022
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7 Reads
It is shown how one, guided by causality, starting from so-called dynamical triangulations, is led to a candidate of quantum gravity that describes our Universe. This theory is based on W- and Jordan algebras. It explains how our Universe was created, how cosmic inflation began and ended, how the topology and the geometry of our Universe was formed, and what was the origin of Big Bang energy. The theory also leads to a modified Friedmann equation which explains the present accelerating expansion of our Universe without appealing to the cosmological constant.
August 2022
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17 Reads
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2 Citations
We have already shown how a modified Friedmann equation, originating from a model of the Universe built from a certain algebra, is able to explainthe difference between the Hubble constants extracted from CMB data and from local measurements. In this article we show that the same model also describes aspects of the large scale structure of the Universe well.
March 2022
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12 Reads
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12 Citations
Modern Physics Letters A
In this paper, we show how a modified Friedmann equation, originating from a model of the universe built from a certain [Formula: see text] algebra, has the potential to explain the difference between the Hubble constants extracted from CMB data and from supernova data.
November 2021
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10 Reads
We show how a modified Friedmann equation, originating from a model of the universe built from a certain algebra, has the potential to explain the difference between the Hubble constants extracted from CMB data and from supernova data.
February 2021
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44 Reads
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16 Citations
Physics Letters B
We show that in a two-dimensional model of quantum gravity the summation over all possible wormhole configurations leads to a kind of Coleman mechanism where the cosmological constant plays no role for large universes. Observers who are unable to observe the change in topology will naturally interpret the measurements of the size of the universe as being caused by a fluctuating cosmological constant, rather than fluctuating topology of spacetime.
January 2021
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9 Reads
We show that in a two-dimensional model of quantum gravity the summation over all possible wormhole configurations leads to a kind of Coleman mechanism where the cosmological constant plays no role for large universes. Observers who are unable to observe the change in topology will naturally interpret the measurements of the size of the universe as being caused by a fluctuating cosmological constant, rather than fluctuating topology of spacetime.
... Recently, Ambjørn and Watabiki [13] have proposed a theory suggesting that the current acceleration of the universe could be caused by the fusion of our universe with other "baby" universes. This approach, which eliminates the need for a cosmological constant, introduces a modification to the Friedmann equations, demonstrating how the influence of these external universes could explain the expansion rate without invoking dark energy. ...
December 2023
... In contrast, Refs. [2,3] (see also [4,5]) put forward a model of quantum gravity that has a quite concrete and physical basis, namely the absorption and emission of baby universes by the observed Universe. It leads to a modified Friedmann equation for the expansion of the Universe, which depends only on a coupling constant g, and whose sole energy contributions at late times is from the nonrelativistic matter (baryons plus dark matter); the accelerated expansion arises through a modification of the Friedmann equation rather than through an explicit dark energy contribution. ...
August 2023
Modern Physics Letters A
... Despite being defined for Lorentzian signature, numerical methods are applicable due to the presence of a well-defined Wick rotationa rarity in quantum gravity beyond perturbation theory. One of the outcomes of these simulations reveals that when the spatial topology is T 3 , the effective action as a function of the three-volume V (t) at proper time t is given by [38,39]: ...
March 2022
Modern Physics Letters A
... However, if the Friedmann equation makes us possible to go back to the time when the universe was a point, such a point state has the infinite energy density, and it becomes spacetime singularity. 7 We should also note that the topologies of the point and the space with expanse are different. Moreover, suppose that the time when the universe was a point state is the origin of time coordinate, there is a question whether there exists a negative time. ...
February 2021
Physics Letters B
... The universe grew from infancy to puberty, becoming denser and hotter, with energy dominated by dark energy and less dark matter, none of which can be identified in the laboratory (Ratra & Vogeley, 2008). Several measurements have shown that the universe was much smaller and heated at the beginning of its existence than it is now (Ambjørn & Watabiki, 2020). ...
May 2020
Nuclear Physics B
... This also, to the best of our knowledge, is the first work ever which has considered such cosmological singularities in the context of a multiverse. It is also important to mention how this current work differs from previous treatments of the multiverse in this cosmological paradigm as in [52,86] as while in these papers there have been certain mentions of singularities, a full and extensive analysis taking into account all kinds of future cosmological singularities has not been undertaken in any similar way to the one we have presented here. Our work has comprehensively taken the status quo of various cosmologically interesting parameters and have investigated their evolution towards future times, focusing on how any blowups in these parameters can be achieved and whether one can even have blowups in them, which we have ended up showing is not the case. ...
September 2017
Modern Physics Letters A
... We have proposed a modified Friedmann equation [1][2][3] which changes the late time cosmology, such that one does not need a cosmological constant to explain the present day acceleration of our Universe. While it is our hope that this modified Friedmann equation can eventually be derived from an underlying microscopic theory [4][5][6][7], we will here treat it as a phenomenological model that we can obtain in a simple way from the standard Friedmann equation. 1 Our starting point is the Hartle-Hawking minisuperspace action, which after the rotation of the conformal factor can be written as ...
April 2017
Acta Physica Polonica B Proceedings Supplement
... We have proposed a modified Friedmann equation [1][2][3] which changes the late time cosmology, such that one does not need a cosmological constant to explain the present day acceleration of our Universe. While it is our hope that this modified Friedmann equation can eventually be derived from an underlying microscopic theory [4][5][6][7], we will here treat it as a phenomenological model that we can obtain in a simple way from the standard Friedmann equation. 1 Our starting point is the Hartle-Hawking minisuperspace action, which after the rotation of the conformal factor can be written as ...
March 2017
Physics Letters B
... We have proposed a modified Friedmann equation [1][2][3] which changes the late time cosmology, such that one does not need a cosmological constant to explain the present day acceleration of our Universe. While it is our hope that this modified Friedmann equation can eventually be derived from an underlying microscopic theory [4][5][6][7], we will here treat it as a phenomenological model that we can obtain in a simple way from the standard Friedmann equation. 1 Our starting point is the Hartle-Hawking minisuperspace action, which after the rotation of the conformal factor can be written as ...
May 2015
Physics Letters B
... One advantage of studying GCDT through the graphs consisting of tree subgraphs and a finite number of faces is that there exists a one-matrix model with a cubic interaction and a tadpole term which allows us to introduce the parameter θ mentioned above and which can interpolate between DT and GCDT (realized on the set of graphs with a finite number of faces) [23,25]. It also allowed for an intuitive understanding of this interpolation in terms of an inhomogeneous lattice structure, as well as the possibility of new scaling limits using this inhomogeneous lattice structure [26]. ...
June 2014
Physics Letters B
