Category: cosmology – Page 234
Lensing of the cosmic microwave background indicates 12-billion-year-old galaxies had dark matter.
Australian scientists are making strides towards solving one of the greatest mysteries of the universe: the nature of invisible “dark matter”.
Peer long enough into the heavens, and the Universe starts to resemble a city at night. Galaxies take on characteristics of streetlamps cluttering up neighborhoods of dark matter, linked by highways of gas that run along the shores of intergalactic nothingness.
This map of the Universe was preordained, laid out in the tiniest of shivers of quantum physics moments after the Big Bang launched into an expansion of space and time some 13.8 billion years ago.
Yet exactly what those fluctuations were, and how they set in motion the physics that would see atoms pool into the massive cosmic structures we see today is still far from clear.
These black holes are not absorbing matter from a nearby star, making them incredibly hard to find.
I promise you: this post is going to tell a scientifically coherent story that involves all five topics listed in the title. Not one can be omitted.
My story starts with a Zoom talk that the one and only Lenny Susskind delivered for the Simons Institute for Theory of Computing back in May. There followed a panel discussion involving Lenny, Edward Witten, Geoffrey Penington, Umesh Vazirani, and your humble shtetlmaster.
Lenny’s talk led up to a gedankenexperiment involving an observer, Alice, who bravely jumps into a specially-prepared black hole, in order to see the answer to a certain computational problem in her final seconds before being ripped to shreds near the singularity. Drawing on earlier work by Bouland, Fefferman, and Vazirani, Lenny speculated that the computational problem could be exponentially hard even for a (standard) quantum computer. Despite this, Lenny repeatedly insisted—indeed, he asked me again to stress here—that he was not claiming to violate the Quantum Extended Church-Turing Thesis (QECTT), the statement th at all of nature can be efficiently simulated by a standard quantum computer. Instead, he was simply investigating how the QECTT needs to be formulated in order to be a true statement.
Ever since the start of the hot Big Bang, time ticks forward as the Universe expands. But could time ever run backwards, instead?
What would happen if you fell into a black hole? Join James Beacham, particle physicist at the Large Hadron Collider at CERN, as he explores what happens when the fabric of reality – physical or societal – gets twisted beyond recognition.
Watch the Q&A with James here: https://youtu.be/Q37oEB4bNSI
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James Beacham searches for answers to the biggest open questions of physics using the largest experiment ever, the Large Hadron Collider at CERN. He hunts for dark matter, gravitons, quantum black holes, and dark photons as a member of the ATLAS collaboration, one of the teams that discovered the Higgs boson in 2012.
In addition to his research, he is a frequent keynote speaker about science, innovation, the future of technology, and art at events and venues around the world, including the American Museum of Natural History, the Royal Institution, SXSW, and the BBC, as well as private events for companies and corporations, including KPMG, Bain, Dept Agency, and many others.
This talk was recorded at the Royal Institution on 28 October 2021.
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Why is there something rather than nothing? And what does ‘nothing’ really mean? More than a philosophical musing, understanding nothing may be the key to unlocking deep mysteries of the universe, from dark energy to why particles have mass. Journalist John Hockenberry hosts Nobel laureate Frank Wilczek, esteemed cosmologist John Barrow, and leading physicists Paul Davies and George Ellis as they explore physics, philosophy and the nothing they share.
This program is part of the Big Ideas Series, made possible with support from the John Templeton Foundation.
The World Science Festival gathers great minds in science and the arts to produce live and digital content that allows a broad general audience to engage with scientific discoveries. Our mission is to cultivate a general public informed by science, inspired by its wonder, convinced of its value, and prepared to engage with its implications for the future.
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Original Program Date: June 12, 2009
MODERATOR: John Hockenberry.
PARTICIPANTS: George Ellis, Frank Wilczek, John Barrow, Paul Davies.
Introduction 00:00