Category Archives: Cosmology

On the nature of time in string theory

The journal Foundations of Physics commemorates “Forty Years of String Theory.” Vijay Balasubramanian (University of Pennsylvania) steps back and ask what we do not understand about time. What is time?  Within the broader quantum gravity community outside string theory there has … Continue reading

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Haiman in Nature, “Cosmology: A smoother end to the dark ages”

“Independent lines of evidence suggest that the first stars, which ended the cosmic dark ages (lasting for 100 million years), came in pairs rather than singly. The appearance of the first stars marked a significant milestone, separating the history of … Continue reading

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Peebles in Nature, “How galaxies got their black holes”

“A large galaxy usually has a central, compact massive object, termed a relativistic black hole for want of a better idea of what it is, that can produce great bursts of energy. When the black hole is surrounded by a … Continue reading

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Kane in Physics Today, “String theory and the real world”

“String theory solutions make unambiguous, testable predictions about our four-dimensional universe. To test string theory is like to test Newton’s second law F = ma (a relation between the force F on a particle with mass m and its acceleration … Continue reading

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Bowman and Rogers in Nature, “A lower limit of Δz > 0.06 for the duration of the reionization epoch”

“The Epoch of Reionization (EOR) refers to the period in the history of the universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources. These sources may have been stars, galaxies, quasars, … Continue reading

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Moss, Scott, Zibin, “No evidence for anomalously low variance circles on the sky”

Gurzadyan & Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). An independent analysis has confirmed such a result. However, properly simulated Gaussian CMB data contain just the … Continue reading

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Gianfranco Bertone, “The moment of truth for WIMP Dark Matter”

Gianfranco Bertone, “The moment of truth for WIMP Dark Matter,” ArXiv, Nov. 17, 2010 [Nature 468: 389–393, 18 November 2010], tell us everything we want to know about WIMP particles as candidates for dark matter. Let us summarize the paper. We know … Continue reading

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