Avshalom Elitzur, Claudia de Rham and Harry Cliff debate the relationship between mystery and scientific discovery.
Does science eradicate mystery or expand it?
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That the universe began seems astonishing. What brought it about? What forces were involved? How did the laws of nature generate the vast expanse of billions of galaxies of billions of stars and planets in the structures that we see today? What new physics was involved? What more must we learn?
Continue reading “Alexander Vilenkin — Why Did Our Universe Begin?” »
J0524-0336 contains 100,000 times more lithium than the sun does at its current age. This amount challenges the prevailing models of how stars evolve.
Researchers at the University of Colorado, Boulder; KU Leuven; the Flatiron Institute and the University of Wisconsin–Madison recently set out to answer a long-standing research question, specifically whether charged particles in the turbulent flows commonly surrounding black holes and other compact objects can be accelerated to very high energies.
The striking object appeared as bright as Saturn in the vicinity of the constellation Cassiopeia, and historical chronicles from China and Japan recorded it as a “guest star.”
Chinese astronomers used this term to signify a temporary object in the sky, often a comet or, as in this case, a supernova — a cataclysmic explosion of a star at the end of its life.
The object, now known as SN 1,181, is one of a handful of supernovas documented before the invention of telescopes, and it has puzzled astronomers for centuries.
With the detection of a long-predicted “neutrino fog,” the search for particles of dark matter has entered a new age of both possibility and peril.
The decades-long search for dark matter could ultimately end in an impasse.
Something seems to be missing from the universe, and the favored model of physics calls it “dark matter” – but despite a century of searching, it remains a no-show. A new paper proposes an alternative hypothesis, showing how gravity could exist without mass and produce many of the same effects we ascribe to dark matter.
Einstein’s theory of general relativity is still our best model for describing gravity. As you might remember from high school physics class, gravity is the force that arises from masses resting on the fabric of spacetime. The more mass an object has, the deeper the “dip” in spacetime and the stronger the gravitational pull.
But starting in the 1930s, some strange astronomical observations began to raise questions. Galaxy clusters seemed to be moving much too fast to stay stable based on visible matter, suggesting that far more matter was present than we could see. That led to the hypothesis that huge amounts of invisible stuff – which was dubbed dark matter – pervaded the universe. The idea has held surprisingly strong in observations in the decades since, backed up by the motions of stars within galaxies and the bending and magnifying of light through gravitational lenses.
Join Brian Greene and a team of researchers testing Google’s quantum computer to glean new insights about quantum gravity from their impressive–if controversial–results.
Participants:
Maria Spiropúlu.
Joseph Lykken.
Daniel Jafferis.
Continue reading “Did Einstein Crack the Biggest Problem in Physics…and Not Know It?” »
New observations reveal neutron stars paired with stars like our Sun. Astronomers have uncovered what appear to be 21 neutron stars in orbit around stars like our Sun. The discovery is surprising because it is not clear how a star that exploded winds up next to a star like our Sun.
Most stars in our universe come in pairs. While our own Sun is a loner, many stars like our Sun orbit similar stars, while a host of other exotic pairings between stars and cosmic orbs pepper the universe. Black holes, for example, are often found orbiting each other. One pairing that has proved to be quite rare is that between a Sun-like star and a type of dead star called a neutron star.
Now, astronomers led by Caltech’s Kareem El-Badry have uncovered what appear to be 21 neutron stars in orbit around stars like our Sun. Neutron stars are dense burned-out cores of massive stars that exploded. On their own, they are extremely faint and usually cannot be detected directly. But as a neutron star orbits around a Sun-like star, it tugs on its companion, causing the star to shift back and forth in the sky. Using the European Space Agency’s Gaia mission, the astronomers were able to catch these telltale wobbles to reveal a new population of dark neutron stars.
When neutron stars merge the result is usually a black hole. But sometimes its a more massive, stable neutron star.
