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Category: cosmology

Just when you thought one of the most bizarre things in space was something that eats massive amounts of light and energy and would probably shred you with its gravitational forces, what if it was something even harder to imagine?

Black holes are supposed to have a singularity—a point that is so small and dense we can’t even fathom it—in the middle of all that swirling light and gas. But what if at least some cosmic phenomena that look like black holes are actually cosmic objects full of dark energy? That is what astrophysicists Kevin Croker and Joel Weiner of the University of Hawai’i at Manoa recently published in a study in The Astrophysical Journal that tries to prove these hypothetical Generic Objects of Dark Energy (GEODEs) exist.

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CERN congratulates James Peebles, Michel Mayor and Didier Queloz on the award of the Nobel Prize in physics “for contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos”. Peebles receives the prize “for theoretical discoveries in physical cosmology” and Mayor and Queloz are recognised “for the discovery of an exoplanet orbiting a solar-type star”.

Cosmology studies the universe’s origin, structure and ultimate fate. Peebles’ theoretical framework of cosmology, developed since the mid-1960s, is the foundation of our knowledge of the cosmos today. Thanks to his seminal theoretical work, physicists now have a model that can describe the universe from its earliest moments to the present day, and into the distant future.

Meanwhile, Mayor and Queloz have explored our cosmic neighbourhood and announced in 1995 the first discovery of an exoplanet – a planet outside our Solar System – orbiting a solar-type star in the Milky Way. The discovery of this exoplanet, dubbed 51 Pegasi b, was a milestone in astronomy and has since led to the discovery of more than 4000 exoplanets in our galaxy.

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Two University of Hawaiʻi at Mānoa researchers have identified and corrected a subtle error that was made when applying Einstein’s equations to model the growth of the universe.

Physicists usually assume that a cosmologically large system, such as the universe, is insensitive to details of the small systems contained within it. Kevin Croker, a postdoctoral research fellow in the Department of Physics and Astronomy, and Joel Weiner, a faculty member in the Department of Mathematics, have shown that this assumption can fail for the compact objects that remain after the collapse and explosion of very large stars.

“For 80 years, we’ve generally operated under the assumption that the universe, in broad strokes, was not affected by the particular details of any small region,” said Croker. “It is now clear that general relativity can observably connect collapsed stars—regions the size of Honolulu—to the behavior of the universe as a whole, over a thousand billion billion times larger.”

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Dark matter, which researchers believe make up about 80% of the universe’s mass, is one of the most elusive mysteries in modern physics. What exactly it is and how it came to be is a mystery, but a new Johns Hopkins University study now suggests that dark matter may have existed before the Big Bang.

The study, published August 7 in Physical Review Letters, presents a new idea of how was born and how to identify it with astronomical observations.

“The study revealed a new connection between particle physics and astronomy. If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way. This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too,” says Tommi Tenkanen, a postdoctoral fellow in Physics and Astronomy at the Johns Hopkins University and the study’s author.

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The standard model of physics remains incomplete. Could supersymmetry fill the gaps? From whether supersymmetric particles could fix the mass of the Higgs Boson to what this would mean for string theory, the world’s leading thinkers explain all.

John Ellis is a British theoretical physicist who is currently Clerk Maxwell Professor of Theoretical Physics at King’s College London. He was Division Leader for the CERN theory division, a founding member of the LEPC and of the LHCC at CERN and currently chair of the committee to investigate physics opportunities for future proton accelerators.

Catherine Heymans is a Professor of Astrophysics and European Research Council Fellow at the University of Edinburgh. She is also the Director of the German Centre for Cosmological Lensing at the Ruhr-University Bochum, Germany.

Ben Allanach is a member of the Department of Applied Mathematics and Theoretical Physics High Energy Physics research group and The Cambridge SUSY Working Group based at the Cavendish Laboratory.

Subir Sarkar is a physicist at the University of Oxford, where he is head of the Particle Theory Group at the Rudolf Peierls Centre for Theoretical Physics. His research interests are at the interface between fundamental physics and astrophysics & cosmology — specifically theoretical aspects of dark matter, inflation and large-scale structure formation.

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