Archivi tag: cosmic background radiation

Observational anomalies challenging the Lambda-CDM cosmological model

In the current paradigm of the Lambda-CDM cosmology, the fundamental properties of the Universe are believed to be well understood, with only minor adjustment of the basic model being left to be done. The global picture of an expanding Universe originating during a singularity at Big Bang is now taken for granted, and some basic properties of the Universe are considered to be known with amazing accuracy. For instance, according to Lambda-CDM concordance cosmology, the age of the Universe is 13.798±0.037 Gyr, quoted with a precision higher than the one with which we know the age of our planet. Continua a leggere Observational anomalies challenging the Lambda-CDM cosmological model


String Theory & Cosmology: New Ideas Meet New Experimental Data

This is the golden age of cosmology. Once a philosophical subject, cosmology has burgeoned into a precision science as ground and space-based astronomical observations supply a wealth of unprecedently precise cosmological measurements. Questions that were recently the stuff of speculation can now be analyzed in the context of rigorous, predictive theoretical frameworks whose viability is determined by observational data. To address key questions about our universe, especially at the energy scales characteristic of its earliest moments, one must invoke a theory of quantum gravity, such as string theory. Conversely, observational cosmology is our most promising window for testing fundamental theories at ultra-high energies. Continua a leggere String Theory & Cosmology: New Ideas Meet New Experimental Data

The Primordial Universe after Planck

It is anticipated that the new results from the Planck satellite, based on the full mission data and including the Planck analyses in polarisation, will have been released some time before the meeting. It will therefore be timely to discuss the physics of the primordial universe, both from a theoretical and observational points of view. Continua a leggere The Primordial Universe after Planck

Planck 2014 – The Microwave Sky in Temperature and Polarization

The Planck Collaboration will present the latest scientific results from ESA’s Planck satellite during a conference to be held from 1 to 5 December 2014 in Ferrara, Italy. Launched in 2009, Planck was designed to map the sky in nine frequencies from microwave to sub-millimetre wavelengths, to study the anisotropies of the Cosmic Microwave Background (CMB) radiation in unprecedented detail. These anisotropies can be detected in the temperature of the CMB as well as in its polarisation. Continua a leggere Planck 2014 – The Microwave Sky in Temperature and Polarization

Cosmology after Planck

The Planck Satellite has transformed the accuracy of cosmological observations, which allows to constrain cosmological models with unprecedented precision. The Planck observations have far reaching impact on the possible cosmological models and interpretations. This MIAPP workshop “Cosmology after Planck” will bring together observers and theorists to provide a platform for presenting and discussing the Planck Satellite results in the context of cosmological models. In particular we will discuss the polarization measurements, constraints on primordial Non-Gaussianity, the effect and exploitation of CMB lensing, constraints on inflationary models, probes of the reionization history of the Universe, Sunyaev-Zel’dovich galaxy cluster observations and the future of CMB observations.

Latest News from the Universe: LambdaWDM, CMB,Warm Dark Matter, Dark Energy, Neutrinos and Sterile Neutrinos

The new concordance model in agreement with observations: ΛWDM (Lambda-dark energy- Warm Dark Matter). Recently, Warm (keV scale) Dark Matter emerged impressively over CDM (Cold Dark Matter) as the leading Dark Matter candidate. Astronomical evidence that Cold Dark Matter (LambdaCDM) and its proposed tailored baryonic cures do not work at galactic and small scales is staggering. LambdaWDM solves naturally the problems of LambdaCDM and agrees remarkably well with the observations at galactic and small scales as well as large and cosmological scales. In contrast, LambdaCDM simulations only agree with observations at large scales. In the context of this new Dark Matter situation, which implies novelties in the astrophysical, cosmological, particle and nuclear physics context, the 18th Paris Colloquium 2014 is devoted to the Latest News from the Universe. Continua a leggere Latest News from the Universe: LambdaWDM, CMB,Warm Dark Matter, Dark Energy, Neutrinos and Sterile Neutrinos

Testing general relativity with the ‘ancient light’

The UC San Diego astrophysicists employed the HuanTran Telescope in Chile to measure the polarization of the cosmic microwave background. Credit: POLARBEAR

Un gruppo di astrofisici dell’University of California a San Diego hanno misurato le minuscole distorsioni gravitazionali nella radiazione polarizzata che risale all’Universo delle origini. Lo studio di queste microonde primordiali potrà fornire un importante test cosmologico per verificare alcune concetti fondamentali della relatività generale, permettendo non solo di stimare la massa dei neutrini ma anche di capire come sono distribuite nello spazio sia la materia scura che l’energia scura.

UCSD: Radiation from Early Universe Found Key to Answer Major Questions in Physics
arXiv: A Measurement of the Cosmic Microwave Background B-Mode Polarization Power Spectrum at Sub-Degree Scales with POLARBEAR
arXiv: Measurement of the Cosmic Microwave Background Polarization Lensing Power Spectrum with the POLARBEAR experiment

Lost in a multiverse

I recenti risultati pubblicati dal gruppo di Harvard sull’esperimento BICEP2 sono stati interpretati come la “prima evidenza diretta” dell’inflazione cosmica dovuta al passaggio delle onde gravitazionali primordiali le cui tracce sono state impresse nella radiazione cosmica di fondo (post). Non solo, ma c’è chi dice che questi dati potrebbero essere collegati a qualcosa ancora di più strano che gli astronomi chiamano multiverso. Secondo questa ipotesi affascinante, il nostro Universo non sarebbe l’unico ma sarebbe parte di una grande vastità di universi che formano una sorta di gigantesco “albero cosmico” il cui numero potrebbe essere dell’ordine di

quasi impronunciabile. Ma se questi universi esistono davvero, non li vediamo perchè dal momento in cui è nato il nostro Universo non c’è stato abbastanza tempo affinchè la luce si propagasse per raggiungere il nostro orizzonte cosmico. Dunque, essi si troverebbero al di là del nostro limite osservativo e perciò non potranno mai essere rivelati, almeno in linea di principio. Come fanno allora i cosmologi ad affermare che esistono invece delle evidenze a favore della loro esistenza?

Continua a leggere Lost in a multiverse

Recent BICEP2 results could be an experimental artifact

Swirling controversy. The purported swirls in the cosmic microwave background could in fact be a spurious signal from within our galaxy, a rumor suggests.
Swirling controversy. The purported swirls in the cosmic microwave background could in fact be a spurious signal from within our galaxy, a rumor suggests.

Qualche settimana fa, la notizia relativa alla scoperta della “prima evidenza diretta” dell’inflazione cosmica, annunciata dai ricercatori dell’Harvard CMB Group che lavorano all’esperimento BICEP2, potrebbe rivelarsi un “artefatto sperimentale”. E’ oggi quanto circola tra gli addetti ai lavori nonostante i ricercatori di Harvard abbiano già sottolineato che i risultati saranno soggetti ad una serie di controlli.

More at Science: Blockbuster Big Bang Result May Fizzle, Rumor Suggests

See update(s) here: Follow up on BICEP

The Conversation: Has dust clouded the discovery of gravitational waves? [UPDATE]

Max Tegmark ‘welcomes’ the multiverse idea

What is the Universe made of? The ancient Greeks conceived of the “atom”, the indivisible unit of matter. Today’s physicists talk of smaller particles, quarks and electrons, neutrinos, Higgs Bosons and photons. Understand them, and the forces that hold everything together, and we may finally get a handle on what makes it all tick. The trouble is, the more we drill down into the subatomic world, the more complexity we find. The bedrock of reality seems as elusive as ever. Perhaps, says a leading theoretical physicist Max Tegmark, we do not live in a world of particles and forces at all, but of pure mathematics.

The Telegraph: It’s goodbye to the universe – hello to the multiverse