Physics Archives

March 12, 2021March 12, 2021 by Brian Koberlein

Alcubierre Gives us an Update on his Ideas About Warp Drives

The Enterprise using warp drive, as seen in Star Trek Beyond. Credit: Paramount Pictures

If you want a galaxy-spanning science fiction epic, you’re going to need faster than light travel. The alternative is taking decades or centuries to reach an alien star system, which isn’t nearly as much fun. So, you start with some wild scientific idea, add a bit of technobabble, and poof! Quam Celerrime ad Astra. Everything from wormholes to hyperspace has been used in sci-fi, but perhaps the best known FTL trope is warp drive.

February 19, 2021February 19, 2021 by Brian Koberlein

A new Approach Could Tease out the Connection Between Gravity and Quantum Mechanics

In physics, there are two main ways to model the universe. The first is the classical way. Classical models such as Newton’s laws of motion and Einstein’s theory of relativity assume that the properties of an object such as its position and motion are absolute. There are practical limits to how accurately we can measure an object’s path through space and time, but that’s on us. Nature knows their motion with infinite precision. Quantum models such as atomic physics assume that objects are governed by interactions. These interactions are probabilistic and indefinite. Even if we constrain an interaction to limited outcomes, we can never know the motion of an object with infinite precision, because nature doesn’t allow it.

February 12, 2021February 12, 2021 by Andy Tomaswick

Quantum Theory Proposes That Cause and Effect Can Go In Loops

Causality is one of those difficult scientific topics that can easily stray into the realm of philosophy. Science’s relationship with the concept started out simply enough: an event causes another event later in time. That had been the standard understanding of the scientific community up until quantum mechanics was introduced. Then, with the introduction of the famous “spooky action at a distance” that is a side effect of the concept of quantum entanglement, scientists began to question that simple interpretation of causality.

Now, researchers at the Université Libre de Bruxelles (ULB) and the University of Oxford have come up with a theory that further challenges that standard view of causality as a linear progress from cause to effect. In their new theoretical structure, cause and effect can sometimes take place in cycles, with the effect actually causing the cause.

February 1, 2021February 1, 2021 by Matt Williams

Neutrinos Have a Newly Discovered Method of Interacting With Matter, Opening up Ways to Find Them

SCGSR Awardee Jacob Zettlemoyer, Indiana University Bloomington, led data analysis and worked with ORNL’s Mike Febbraro on coatings, shown under blue light, to shift argon light to visible wavelengths to boost detection. Credit: Rex Tayloe/Indiana University

The neutrino is a confounding little particle that is believed to have played a major role in the evolution of our Universe. They also possess very little mass, have no charge, and interact with other particles only through the weak nuclear force and gravity. As such, finding evidence of their interactions is extremely difficult and requires advanced facilities that are shielded to prevent interference.

One such facility is the Oak Ridge National Laboratory (ORNL) where an international team of researchers are conducting the COHERENT particle physics experiment. Recently, researchers at COHERENT achieved a major breakthrough when they found the first evidence of a new kind of neutrino interaction, which effectively demonstrates a process known as coherent elastic neutrino-nuclear scattering (CEvNS).

January 10, 2021January 15, 2021 by Brian Koberlein

There's no way to Measure the Speed of Light in a Single Direction

Special relativity is one of the most strongly validated theories humanity has ever devised. It is central to everything from space travel and GPS to our electrical power grid. Central to relativity is the fact that the speed of light in a vacuum is an absolute constant. The problem is, that fact has never been proven.

December 18, 2020December 18, 2020 by Brian Koberlein

A new Type of Atomic Clock Uses Entangled Atoms. At Most, it Would be off by 100 Milliseconds Since the Beginning of the Universe

Lasers are used to squeeze atoms and entangle them. Credit: MIT

Measuring time is about counting steps. Whether it’s the drip-drip of a water clock, the tic-toc of a mechanical clock, or the oscillating crystal of a quartz watch. Any accurate timepiece is built around counting the steps of something regular and periodic. Nothing is perfectly regular, so no clock keeps perfect time, but our timepieces are getting very, very accurate.

October 26, 2020October 26, 2020 by Paul M. Sutter

There’s a new record for the shortest time measurement: how long it takes light to cross a hydrogen molecule

HD+ molecular ions (yellow and red pairs of dots: proton and deuteron) suspended in an ultra-high vacuum between atomic ions (blue dots). Credit: HHU / Alighanbari, Hansen, Schiller

To measure small differences in time, you need a really tiny clock, and researchers in Germany have discovered the smallest known clock: a single hydrogen molecule. Using the travel of light across the length of that molecule, those scientists have measured the smallest interval of time ever: 247 zeptoseconds. Don’t know what a “zepto” is? Read on…

September 27, 2020September 27, 2020 by Brian Koberlein

Time Travel, Without the Pesky Paradoxes

A time machine connects to the past. Credit: David Revoy / Blender Foundation (CC BY 3.0)

Time travel is a staple of science fiction, and not without reason. Who wouldn’t want to go back in time to explore history, or save the world from catastrophe. Time travel has also been deeply studied within the context of theoretical physics because it tests the limits of our scientific theories. If time travel is possible, it has implications for everything from the origin of the universe to the existence of free will. One of the central problems of time travel theory is that it gives rise to logical paradoxes. But a couple of researchers think they have solved the pesky paradox problem.

September 24, 2020September 24, 2020 by Evan Gough

Even Comets Can Have Auroras. Comet 67P/Churyumov-Gerasimenko Does

Data from Southwest Research Institute-led instruments aboard ESA’s Rosetta spacecraft helped reveal unique ultraviolet auroral emissions around irregularly shaped Comet 67P. Although these auroras are outside the visible spectra, other auroras have been seen at various planets and moons in our solar system and even around a distant star. Image Credit: ESA/Rosetta/NAVCAM

The ESA’s Rosetta mission to Comet 67P/Churyumov-Gerasimenko ended four years ago. On September 30th 2016 the spacecraft was directed into a controlled impact with the comet, putting an end to its 12.5 year mission. Scientists are still working with all its data and making new discoveries.

A new study based on Rosetta data shows that Comet 67P has its own aurora.

September 9, 2020September 10, 2020 by Matt Williams

Behold! The Black Hole Collision Calculator!

This image shows two massive black holes in the OJ 287 galaxy. The smaller black hole orbits the larger one, which is also surrounded by a disk of gas. When the smaller black hole crashes through the disk, it produces a flare brighter than 1 trillion stars. Credit: NASA/JPL-Caltech

Black holes have been the subject of intense interest ever since scientists began speculating about their existence. Originally proposed in the early 20th century as a consequence of Einstein’s Theory of General Relativity, black holes became a mainstream subject a few decades later. By 1971, the first physical evidence of black holes was found and by 2016, the existence of gravitational waves was confirmed for the first time.

This discovery touched off a new era in astrophysics, letting people know collision between massive objects (black holes and/or neutron stars) creates ripples in spacetime that can be detected light-years away. To give people a sense of how profound these events are, Álvaro Díez created the Black Hole Collision Calculator (BHCC) – a tool that lets you see what the outcome of a collision between a black hole and any astronomical object would be!