Month: September 2022

SEARCH FOR SYMMETRICAL UNIVERSE. “The conclusion of their study, after several years of effort, was that the primordial Universe, at least in the standard cosmological model, does not provide enough time for a matter-antimatter universe to create structures large enough to evade the constraints of the diffuse gamma-ray flux.” https://lnkd.in/daA2SgMy View in LinkedIn

INCONSISTENCY. “Indeed, if matter and antimatter have both positive gravitational masses and respect the equivalence principle, matter-antimatter annihilation continues to occur after the Universe has become transparent, leading to a diffuse high energy gamma-ray background, already difficult to justify in the early 1970s, at the epoch of the SAS-2 satellite, and clearly inconsistent with the much more sensitive contemporary satellites, such as the Fermi satellite.” https://lnkd.in/daA2SgMy View in LinkedIn

EARLY CONCLUSIONS. “Glashow et al. “concluded again that even if the primordial universe had succeeded in creating a symmetrical world between matter and antimatter, diffusion of matter and antimatter at their domain boundaries would lead, as soon as the Universe becomes transparent, to an annihilation between matter and antimatter in conflict with observational limits, unless the domains of matter and antimatter had a size exceeding several billion light-years, which seems unrealistic.” https://lnkd.in/daA2SgMy View in LinkedIn

LATER CONCLUSIONS. “But rather obviously, these studies had assumed that matter and antimatter had both a positive gravitational mass. Today, the discovery of a repulsive gravity through observations of SN1a supernovae luminosity distance, called Dark Energy, leads us to be more cautious: indeed, what seemed previously impossible, repulsive gravity, is the major topic of interest in cosmology.” https://lnkd.in/daA2SgMy View in LinkedIn

NEW BRIDGES. “By the 1950s, Bondi had built negative mass solutions that respected the equivalence principle.” https://lnkd.in/daA2SgMy View in LinkedIn

REMAINING OBSTACLES. “Very strong theorems seemed to exclude any possibility of negative mass particles or objects, or more generally violating the positivity of energy.” https://lnkd.in/daA2SgMy View in LinkedIn

TOXIC COMBINATION. “We have stone age emotions, medieval institutions and god-like technology.” (The late Professor EO Wilson, a giant among men). https://www.theguardian.com/environment/2021/dec/27/edward-o-wilson-naturalist-modern-day-darwin-dies?CMP=Share_iOSApp_Other View in LinkedIn

Playing with geometric models can be a source of humbling puzzlement as you realize that childhood learnings have long faded! View in LinkedIn

POSITIVITY OF ENERGY THEOREMS. “But whereas initially these theorems on the positivity of energy appeared as absolute no-go theorems, the increasing number of violations of the energy conditions, first through the quantum effects of the vacuum (for example in the Casimir effect), then from 1998 in an infinitely more significant way with the discovery of Dark Energy, led to question these theorems.” https://lnkd.in/daA2SgMy View in LinkedIn

NEGATIVE MASS. “The demonstration of the existence, in 2014, of perfectly respectable solutions of negative mass “bubbles” without instability as soon as they are placed in an expanding universe (here, the Einstein-de Sitter universe) finally demonstrated that instability does not constitute a sufficient argument to exclude a solution: it is indeed also necessary to calculate the characteristic time of instability, since cosmological solutions are themselves unstable, but with often enormous and therefore acceptable characteristic times.” https://lnkd.in/daA2SgMy View in LinkedIn