Physics Archives

October 19, 2023October 19, 2023 by Matt Williams

Thinking About Time Travel Helps Solve Problems in Physics

Physicists have shown that simulating models of hypothetical time travel can solve experimental problems that appear impossible to solve using standard physics. Credit: Yaroslav Kushta via Getty Images

Time travel. We’ve all thought about it at one time or another, and the subject has been explored extensively in science fiction. Once in a while, it is even the subject of scientific research, typically involving quantum mechanics and how the Universe’s four fundamental forces (electromagnetism, weak and strong nuclear forces, and gravity) fit together. In a recent experiment, researchers at the University of Cambridge showed that by manipulating quantum entanglements, they could simulate what could happen if the flow of time were reversed.

September 29, 2023September 29, 2023 by Brian Koberlein

It's Official, Antimatter Falls Down in Gravity, Not Up

Illustration of how anti-hydrogen can test gravity. Credit: National Science Foundation

It’s a basic fact we’ve all learned in school. Drop any object, be it a baseball, feather, or cat, and it will fall toward the Earth at exactly the same rate. The cat will fortunately land on its feet thanks to a bit of feline grace, but the point is that everything falls at the same rate under gravity. It doesn’t matter what an object is made of, or how heavy it is. While we’ve all been taught this fact, calling it a fact was, until recently, a bit of a lie.

September 20, 2023September 20, 2023 by Evan Gough

Gluttonous Black Holes Eat Faster Than Thought. Does That Explain Quasars?

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser — Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

At the heart of large galaxies like our Milky Way, there resides a supermassive black hole (SMBH.) These behemoths draw stars, gas, and dust toward them with their irresistible gravitational pull. When they consume this material, there’s a bright flare of energy, the brightest of which are quasars.

While astrophysicists think that SMBHs eat too slowly to cause a particular type of quasar, new research suggests otherwise.

August 14, 2023August 14, 2023 by Matt Williams

New Muon g-2 Result Improves the Measurement by a Factor of 2

First results from the Muon g-2 experiment at Fermilab have strengthened evidence of new physics. Credit: Reidar Hahn/Fermilab

At the Fermi National Accelerator Laboratory (aka. Fermilab), an international team of scientists is conducting some of the most sensitive tests of the Standard Model of Particle Physics. The experiment, known as Muon g-2, measures the anomalous magnetic dipole moment of muons, a fundamental particle that is negatively charged (like electrons) but over 200 times as massive. In a recent breakthrough, scientists at Fermilab made the world’s most precise measurement of the muon’s anomalous magnetic moment, improving the precision of their previous measurements by a factor of 2.

June 17, 2023June 11, 2023 by Paul M. Sutter

The Best Particle Collider in the World? The Sun

A look inside ALICE at the Large Hadron Collider. ALICE is one of the LHC's four particle detectors. Image: CERN/LHC

Recently astronomers caught a strange mystery: extremely high-energy particles spitting out of the surface of the Sun when it was relatively calm. Now a team of theorists have proposed a simple solution to the mystery. We just have to look a little bit under the surface.

February 13, 2023February 16, 2023 by Matt Williams

Are We Entering the Era of Quantum Telescopes?

Beyond James Webb and LUVOIR, the future of astronomy could come down to telescopes that rely on quantum mechanics. Credit: Anton Pozdnyakov

For astronomers, one of the greatest challenges is capturing images of objects and phenomena that are difficult to see using optical (or visible light) telescopes. This problem has been largely addressed by interferometry, a technique where multiple telescopes gather signals, which is then combined to create a more complete picture. Examples include the Event Horizon Telescope, which relies on observatories from around the world to capture the first images of the supermassive black hole (SMBH) at the center of the M87 galaxy, and of Sagittarius A* at the center of the Milky Way.

That being said, classic interferometry requires that optical links be maintained between observatories, which imposes limitations and can lead to drastically increased costs. In a recent study, a team of astrophysicists and theoretical physicists proposed how these limitations could be overcome by relying on quantum mechanics. Rather than relying on optical links, they propose how the principle of quantum entanglements could be used to share photons between observatories. This technique is part of a growing field of research that could lead to “quantum telescopes” someday.

December 13, 2022December 13, 2022 by Alan Boyle

We Have Ignition! Fusion Breakthrough Raises Hopes — and Questions

A color-enhanced image shows the inside of a preamplifier support structure at the National Ignition Facility. (LLNL Photo / Damien Jemison)

For the first time ever, physicists have set off a controlled nuclear fusion reaction that released more energy than what was put into the experiment.

The milestone laser shot took place on Dec. 5 at the U.S. Department of Energy’s National Ignition Facility at Lawrence Livermore National Laboratory in California. The fact that there was a net energy gain qualified the shot, in technical terms, as ignition. “Reaching ignition in a controlled fusion experiment is an achievement that has come after more than 60 years of global research, development, engineering and experimentation,” said Jill Hruby, under secretary of energy for nuclear security and the administrator of the National Nuclear Security Administration.

However, officials acknowledged that it’s still likely to be decades before commercial fusion power becomes a reality. They said the most immediate impact of the breakthrough will be felt in the field of national security and the stewardship of America’s nuclear weapons stockpile.

November 29, 2022November 29, 2022 by Allen Versfeld

The Technique for Detecting Meteors Could be Used to Find Dark Matter Particles Entering the Atmosphere

A perseid meteor, streaking across the night sky. Image credit: Andreas Möller — A Perseid meteor streaks across the sky, leaving a glowing ionized trail. Image credit: Andreas Möller, licensed under

Researchers from Ohio State University have come up with a novel method to detect dark matter, based on existing meteor-detecting technology. By using ground-based radar to search for ionization trails, similar to those produced by meteors as they streak through the air, they hope to use the Earth’s atmosphere as a super-sized particle detector. The results of experiments using this technique would help researchers to narrow down the range of possible characteristics of dark matter particles.

November 28, 2022November 28, 2022 by Evan Gough

Nature’s Ultra-Rare Isotopes Can’t Hide from this New Particle Accelerator

The Facility for Rare Isotope Beams at the University of Michigan will study rare isotopes that last only fractions of a second. Image Credit: FRIB/University of Michigan.

A new particle accelerator at Michigan State University is producing long-awaited results. It’s called the Facility for Rare Isotope Beams, and it was completed in January 2022. Researchers have published the first results from the linear accelerator in the journal Physics Review Letters.

November 4, 2022November 4, 2022 by Evan Gough

IceCube Senses Neutrinos Streaming From an Active Galaxy 47 Million Light-Years Away

This is a Hubble Space Telescope image of the Messier 77 spiral galaxy. Scientists working with the IceCube Neutrino Observatory detected neutrinos emanating from the galaxy's core. Image Credit: By NASA, ESA & A. van der Hoeven - http://www.spacetelescope.org/news/heic1305/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25328266

Researchers using the IceCube Neutrino Observatory have detected neutrinos emanating from the energetic core of an active galaxy millions of light-years away. Neutrinos are difficult to detect, and finding them originating from the galaxy is a significant development. What does the discovery mean?