Abstract The Standard Model Higgs potential becomes unstable at large field values where its quartic coupling negative. While the tunneling lifetime of our current electroweak vacuum is comfortably longer than age universe, quantum fluctuations during inflation might push over barrier, forming patches which be lethal for universe. We study cosmological evolution such regions and find that, leas...

General limits on the cosmological constant (or equivalently the vacuum energy density) are derived for an inflationary universe. This is accomplished under the general assumption of global hyperbolicity and without the use of any special properties like spherical symmetry or homogeneity ofthe underlying spacetime. A clear upper limit of 1/3 is obtained for the vacuum energy density parameterQ~...

We consider a cosmological model in which our Universe is a spherically symmetric bubble wall in 5-dimensional anti-de Sitter spacetime. We argue that the bubble on which we live will undergo collisions with other similar bubbles and estimate the spectrum of such collisions. The collision rate is found to be independent of the age of our Universe. Collisions with small bubbles provide an experi...

Planets like the Earth cannot form unless elements heavier than helium are available. These heavy elements, or ‘metals’, were not produced in the big bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that the presence of giant extrasolar planets at small distances from their host stars, is strongly corr...

Phase transitions in the early universe are prime settings for the production of primordial black holes, since they can break the relatively quiescent homogeneity and isotropy of Friedmann–Robertson–Walker (FRW) cosmologies. These epochs of “symmetry breaking,” moreover, can affect the subsequent development of spacetime by changing the evolution of some FRW parameters, including the present ag...

I start by defining the cosmological parameters H0, Ωm and ΩΛ. Then I show how the age of the universe depends on them, followed by the evolution of the scale parameter of the universe for various values of the density parameters. Then I define strategies for measuring them, and show the results for the recent determination of these parameters from measurements on supernovas of type 1a. Implica...

We discuss the evolution of the Universe from what might be called its quantum origin. We apply the uncertainty principle to the origin of the Universe with characteristic time scale equal to the Planck time to obtain its initial temperature and density. We establish that the subsequent evolution obeying the Einstein equation gives the present temperature of the microwave background close to th...

Age consistency for the Universe today has been an important cosmological test. Even more powerful consistency tests at times as early as 10−32 sec lie ahead in the precision era of cosmology. I outline tests based upon cosmic microwave background (CMB) anisotropy, bigbang nucleosynthesis (BBN), particle dark matter, phase transitions, and inflation. The ultimate cosmic timescale – the fate of ...

At least since the age of the ancient Greeks, humanity has understood the importance of the term Pi, or at least modern humanity has assumed so. Pi, in fact, contains a deeper meaning in a combinatorial universe, one long forgotten, bypassed by the geometrical significance of Pi. This paper explains the importance of Pi as a value in a combinatorial universe. Along the way, the paper proves tha...