Physics Archives

August 20, 2020August 20, 2020 by Matt Williams

NASA’s New Video Shows You What it’s Like Traveling Close to the Speed of Light

If you’re a fan of science fiction, chances are you encountered a few franchises where humanity has spread throughout the known Universe. The ships that allow them to do this, maybe they use a warp drive, maybe they “fold space,” maybe have a faster-than-light (FTL) or “jump” drive. It’s a cool idea, the thought of “going interstellar!” Unfortunately, the immutable laws of physics tell us that this is simply not possible.

However, the physics that govern our Universe do allow for travel that is close to the speed of light, even though getting to that speed would require a tremendous amount of energy. Those same laws, however, also tell us that near-light-speed travel comes with all sorts of challenges. Luckily for all of us, NASA addresses these in a recently-released animed video that covers all the basics of interstellar travel!

August 19, 2020August 19, 2020 by Brian Koberlein

Could a tabletop experiment detect gravitational waves and determine the quantum nature of gravity?

This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Could black holes like these (which represent those detected by LIGO on Dec. 26, 2015) collide in the dusty disk around a quasar's supermassive black hole explain gravitational waves, too? Credit: LIGO/T. Pyle

Perhaps the most surprising prediction of general relativity is that of gravitational waves. Ripples in space and time that spread through the universe at the speed of light. Gravitational waves are so faint that for decades their detection was thought impossible. Even today, it takes an array of laser interferometers several kilometers long to see their effect. But what if we could detect them with a table-top experiment in a university lab?

In a recent paper published in the New Journal of Physics, a team of physicists proposes just such a device. Rather than using beams of light, they suggest using the quantum superposition of a single electron.

July 1, 2020July 3, 2020 by Evan Gough

Complete and Total Mayhem in a Distant Galaxy Collision

The filamentary structures observed by LOFAR at the center of Abell 2255, here reported in red. These radio emissions are due to trails of particles and magnetic fields released by the galaxies during their motion inside the cluster (credits: Botteon et al. (2020) – LOFAR – SDSS).

A cluster of galaxies is nothing trivial. The shocks, the turbulence, the energy, as all of that matter and energy merges and interacts. And we can watch all the chaos and mayhem as it happens.

A team of astronomers are looking at the galaxy cluster Abell 2255 with the European Low-Frequency Array (LOFAR) radio telescope, and their images are showing some never-before-seen details in this actively merging cluster.

June 25, 2020June 25, 2020 by Evan Gough

How an Advanced Civilization Could Exploit a Black Hole for Nearly Limitless Energy

This artist’s impression shows the surroundings of a supermassive black hole, typical of that found at the heart of many galaxies. The black hole itself is surrounded by a brilliant accretion disc of very hot, infalling material and, further out, a dusty torus. There are also often high-speed jets of material ejected at the black hole’s poles that can extend huge distances into space. Observations with ALMA have detected a very strong magnetic field close to the black hole at the base of the jets and this is probably involved in jet production and collimation.

A black hole as a source of energy?

We know black holes as powerful singularities, regions in space time where gravity is so overwhelming that nothing—not even light itself—can escape.

About 50 years ago, British physicist Roger Penrose proposed that black holes could be a source of energy. Now, researchers at the University of Glasgow in Scotland have demonstrated that it may be possible.

June 23, 2020June 22, 2020 by Paul M. Sutter

There’s no evidence that dark matter interacts with any other force but gravity

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

Most of the universe is made of one of two kinds of mysterious substances, called dark matter and dark energy. From all the evidence, these two cosmic components only interact with “normal” matter through the gravitational force. And a recent nuclear experiment reveals no presence of any dark contamination in the bonds between atomic nuclei to a level twenty times better than previously recorded.

June 19, 2020June 19, 2020 by Brian Koberlein

Japanese Dark Matter Detector is Seeing a “Surprising Excess of Events”

The top PMT array with all of the electric cables. Credit: XENON Dark Matter Project

Dark matter is notoriously difficult to detect. So difficult that we haven’t detected it yet. Evidence for dark matter can be seen in everything from the warping of light near galaxies to the way galaxies cluster together. We are pretty sure dark matter is real, but we also know it can’t be made of any type of particle we currently know. But a new study has found some interesting data that could be evidence of dark matter, or not.

June 16, 2020June 15, 2020 by Paul M. Sutter

Spacecraft was able to measure how long neutrons last before they decay

Artist's concept of the MESSENGER spacecraft on approach to Mercury. Credit: NASA/JPL

Using NASA’s MESSENGER spacecraft’s close encounters with Venus and Mercury, researchers were able to measure the lifetime of neutrons, an important prediction of the Standard Model of particle physics.

May 13, 2020May 13, 2020 by Paul M. Sutter

Time Travel Into The Future Is Totally Possible

The ESA's CHEOPS launching aboard a Soyuz-FG rocket from Kourou, French Guiana. Image Credit: ESA - S. Corvaja

Believe it or not, time travel is possible.

In fact, you’re doing it right now. Every single second of every single day you are advancing into your own future. You are literally moving through time, the same way you would move through space. It may seem pedantic, but it’s a very important point. Movement through time is still movement, and you are reaching your own future (whether you like it or not).

April 29, 2020April 29, 2020 by Paul M. Sutter

Can wormholes act like time machines?

Artist illustration of a spacecraft passing through a wormhole to a distant galaxy. Image credit: NASA.

Time travel into the past is a tricky thing. We know of no single law of physics that absolutely forbids it, and yet we can’t find a way to do it, and if we could do it, the possibility opens up all sorts of uncomfortable paradoxes (like what would happen if you killed your own grandfather).

But there could be a way to do it. We just need to find a wormhole first.

April 17, 2020April 17, 2020 by Paul M. Sutter

Gravity is tested down to a scale smaller than the thickness of a human hair

Gravity was the first force of nature to be realized, and in the centuries since we first cracked the code of that all-pervasive pulling power, scientists have continually come up with clever ways to test our understanding. And it’s no surprise why: the discovery of a new wrinkle in the gravitational force could open up vistas of new physics, and maybe even the nature of reality itself.