Archive for the ‘physics’ category

Mar 24, 2024

If Our Part of the Universe is Less Dense, Would That Explain the Hubble Tension?

Posted by in categories: cosmology, physics

In the 1920s, Edwin Hubble and Georges Lemaitre made a startling discovery that forever changed our perception of the Universe. Upon observing galaxies beyond the Milky Way and measuring their spectra, they determined that the Universe was expanding. By the 1990s, with the help of the Hubble Space Telescope, scientists took the deepest images of the Universe to date and made another startling discovery: the rate of expansion is speeding up! This parameter, denoted by Lambda, is integral to the accepted model of cosmology, known as the Lambda Cold Dark Matter (LCDM) model.

Since then, attempts to measure distances have produced a discrepancy known as the “Hubble Tension.” While it was hoped that the James Webb Space Telescope (JWST) would resolve this “crisis in cosmology,” its observations have only deepened the mystery. This has led to several proposed resolutions, including the idea that there was an “Early Dark Energy” shortly after the Big Bang. In a recent paper, an international team of astrophysicists proposed a new solution based on an alternate theory of gravity that states that our galaxy is in the center of an “under-density.”

Continue reading “If Our Part of the Universe is Less Dense, Would That Explain the Hubble Tension?” »

Mar 24, 2024

Emmy Noether’s revolutionary idea explained for anyone, from kindergarteners to PhDs

Posted by in categories: mathematics, physics

A century ago, Emmy Noether published a theorem that would change mathematics and physics. Here’s an all-ages guided tour through this groundbreaking idea.

Mar 23, 2024

Planet-eating stars more common than previously thought, astrophysicists find

Posted by in categories: alien life, physics

New research from Australian scientists shows strong evidence even mid-life stable stars like our sun have engulfed entire planets.

Mar 22, 2024

Discovery Tests Theory on Cooling of White Dwarf Stars

Posted by in categories: energy, physics, space

Open any astronomy textbook to the section on white dwarf stars and you’ll likely learn that they are “dead stars” that continuously cool down over time. New research published in Nature is challenging this theory, with the University of Victoria (UVic) and its partners using data from the European Space Agency’s Gaia satellite to reveal why a population of white dwarf stars stopped cooling for more than eight billion years.

“We discovered the classical picture of all white dwarfs being dead stars is incomplete,” says Simon Blouin, co-principal investigator and Canadian Institute of Theoretical Astrophysics National Fellow at UVic.

“For these white dwarfs to stop cooling, they must have some way of generating extra energy. We weren’t sure how this was happening, but now we have an explanation for the phenomenon.”

Mar 21, 2024

Thermonuclear flames: Astrophysicists use supercomputer to explore exotic stellar phenomena

Posted by in categories: physics, space, supercomputing

Understanding how a thermonuclear flame spreads across the surface of a neutron star—and what that spreading can tell us about the relationship between the neutron star’s mass and its radius—can also reveal a lot about the star’s composition.

Mar 21, 2024

What is emergent gravity, and will it rewrite physics?

Posted by in categories: cosmology, evolution, physics

In Verlinde’s picture of emergent gravity, as soon as you enter low-density regions — basically, anything outside the solar system — gravity behaves differently than we would expect from Einstein’s theory of general relativity. At large scales, there is a natural inward pull to space itself, which forces matter to clump up more tightly than it otherwise would.

This idea was exciting because it allowed astronomers to find a way to test this new theory. Observers could take this new theory of gravity and put it in models of galaxy structure and evolution to find differences between it and models of dark matter.

Over the years, however, the experimental results have been mixed. Some early tests favored emergent gravity over dark matter when it came to the rotation rates of stars. But more recent observations haven’t found an advantage. And dark matter can also explain much more than galaxy rotation rates; tests within galaxy clusters have found emergent gravity coming up short.

Mar 21, 2024

Unveiling the formation of the first galaxies

Posted by in categories: cosmology, physics, supercomputing

Utilizing high-resolution three-dimensional radiation hydrodynamics simulations and a detailed supernova physics model run on supercomputers, a research team led by Dr. Ke-Jung Chen from the Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) has revealed that the physical properties of the first galaxies are critically determined by the masses of the first stars. Their study is published in The Astrophysical Journal.

Mar 20, 2024

Research team establishes synthetic dimension dynamics to manipulate light

Posted by in categories: physics, space

In the realm of physics, synthetic dimensions (SDs) have emerged as one of the frontiers of active research, offering a pathway to explore phenomena in higher-dimensional spaces, beyond our conventional 3D geometrical space. The concept has garnered significant attention, especially in topological photonics, due to its potential to unlock rich physics inaccessible in traditional dimensions.

Mar 20, 2024

Move over, Elon Musk: Nvidia says 2024 is the year of the ‘humanoid’ robot

Posted by in categories: Elon Musk, physics, robotics/AI

Physicists just can’t leave an incomplete theory alone; they try and repair it. When nature is kind, it can lead to a major breakthrough.

Mar 20, 2024

EMP Attack: The Real Science of Electromagnetic Pulse

Posted by in categories: physics, science, space

PBS Member Stations rely on viewers like you. To support your local station, go to:

Sign Up on Patreon to get access to the Space Time Discord!
/ pbsspacetime.

Continue reading “EMP Attack: The Real Science of Electromagnetic Pulse” »

Page 1 of 28012345678Last