Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: physics – Page 154

Sean Carroll: We might solve free will one day. But here’s why I doubt it.

Up next, The great free will debate ► https://youtu.be/3O61I0pNPg8

Debates about the existence of free will have traditionally been fought by two competing camps: those who believe in free will and those who don’t because they believe the Universe is deterministic.

Determinism is the thesis that every event — from when a volcano erupts to what cereal you buy at the supermarket — is a theoretically predictable result of the long chain of events that came before it. Free will, it was long thought, cannot exist in a world where all events are already causally determined.

But free will and determinism aren’t necessarily mutually exclusive. As physicist Sean Carroll told Big Think, the compatibilist conception of free will argues that it makes sense to conceptualize ourselves as able to make free decisions, regardless of whether the Universe is deterministic or indeterministic.

Why? The main argument centers on the phenomenon of emergence.

Continue reading “Does free will violate the laws of physics? | Sean Carroll” | >

Sometimes astrophysics gets super weird.

A recent study of the star’s surface, published in the journal Nature Astronomy, says that we’re seeing Gamma Columbae in a short, deeply weird phase of a very eventful stellar life, one that lets astronomers look directly into the star’s exposed heart.

What’s New – The mix of chemical elements on the surface of Gamma Columbae look like the byproducts of nuclear reactions that should be buried in the depths of a massive star, not bubbling on its surface.

Read more | >

The observations could not be explained by Newton’s law of universal gravitation. An alternative theory of gravity might provide the answer. Astrophysicists observed mysterious behavior in star clusters that could lead to a rewrite of fundamental principles of the theory of gravity and even disprove the existence of dark matter, a press release explains.

The new findings challenge existing preconceptions based on widely-accepted principles from Newton’s law of universal gravitation, which explain the large-scale structure and movements of the universe.

Read more | >

An analysis of more than two decades’ worth of supernova explosions convincingly boosts modern cosmological theories and reinvigorates efforts to answer fundamental questions.

A powerful new analysis has been performed by astrophysicists that places the most precise limits ever on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is made up of about two-thirds dark energy and one-third matter — predominantly in the form of dark matter — and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

Read more | >

A team of astrophysicists has revealed an unusual discovery they say appears to challenge our current understanding of gravity based on Newton’s law of universal gravitation, according to a newly published paper.

The controversial claim, published in the Monthly Notices of the Royal Astronomical Society, appears to be consistent with alternative interpretations about one of physics’ most mysterious fundamental interactions.

In their new study, an international team of astrophysicists says that they came upon the discovery while investigating open star clusters. These formations are created as a gas cloud emerges following the birth of thousands of stars within a relatively short time, the remnants of which are ejected as these clusters of stars ignite and begin to expand, which can result in the formation of anywhere from several dozen, to several thousands of new stars.

Read more | >

A ring-shaped waveguide with a particular pattern of notches can force a light wave to make two round trips before completing an integer number of wave cycles.

Light can travel along a closed path inside a ring of glass or similar material, reflecting repeatedly from the interior surface. Although such closed-loop waves generally have integer values of angular momentum, researchers using a small gear-shaped ring have now demonstrated an ability to generate similar waves with unusual fractional values of angular momentum [1]. As in a Möbius strip, the waves must make two round trips to return to their initial configuration. The ability to tune the angular momentum in this way could give researchers more precise control of light in advanced devices such as single-photon emitters.

Physicists refer to the closed-loop waves as whispering gallery modes, named after an acoustic effect in round rooms, where sounds reflect multiple times off the walls. Ordinarily, a wave of this kind moves around a single closed loop before retracing its earlier path. The phase of the electric field associated with the wave front must go through an integer number M of cycles in making one loop. Technically, this condition also implies that the photons associated with the wave will carry an integer number M units of angular momentum.

Read more | >

An international team of astrophysicists has made a puzzling discovery while analyzing certain star clusters. The finding challenges Newton’s laws of gravity, the researchers write in their publication. Instead, the observations are consistent with the predictions of an alternative theory of gravity. However, this is controversial among experts. The results have now been published in the Monthly Notices of the Royal Astronomical Society.

In their work, the researchers investigated open star clusters. These are formed when thousands of stars are born within a short time in a huge gas cloud. As they “ignite,” the galactic newcomers blow away the remnants of the gas cloud. In the process, the cluster expands considerably. This creates a loose formation of several dozen to several thousand stars. The weak gravitational forces acting between them hold the cluster together.

“In most cases, open star clusters survive only a few hundred million years before they dissolve,” explains Prof. Dr. Pavel Kroupa of the Helmholtz Institute of Radiation and Nuclear Physics at the University of Bonn. In the process, they regularly lose stars, which accumulate in two so-called “tidal tails.” One of these tails is pulled behind the cluster as it travels through space. The other, in contrast, takes the lead like a spearhead.

Read more | >

O.o!!

On Sunday, October 9, Judith Racusin was 35,000 feet in the air, en route to a high-energy astrophysics conference, when the biggest cosmic explosion in history took place. “I landed, looked at my phone, and had dozens of messages,” said Racusin, an astrophysicist at NASA’s Goddard Space Flight Center in Maryland. “It was really exceptional.”

The explosion was a long gamma-ray burst, a cosmic event where a massive dying star unleashes powerful jets of energy as it collapses into a black hole or neutron star. This particular burst was so bright that it oversaturated the Fermi Gamma-ray Space Telescope, an orbiting NASA telescope designed in part to observe such events. “There were so many photons per second that they couldn’t keep up,” said Andrew Levan, an astrophysicist at Radboud University in the Netherlands. The burst even appears to have caused Earth’s ionosphere, the upper layer of Earth’s atmosphere, to swell in size for several hours. “The fact you can change Earth’s ionosphere from an object halfway across the universe is pretty incredible,” said Doug Welch, an astronomer at McMaster University in Canada.

Astronomers cheekily called it the BOAT—“brightest of all time”—and began to squeeze it for information about gamma-ray bursts and the cosmos more generally. “Even 10 years from now there’ll be new understanding from this data set,” said Eric Burns, an astrophysicist at Louisiana State University. “It still hasn’t quite hit me that this really happened.”

Read more | >