Lifeboat Foundation

A hunt for hypothetical axions streaming from Betelgeuse turns up empty but helps physicists set constraints on their properties.

Qubits offer a fast, highly reliable way to solve one of the great mysteries in physics. Some kind of invisible material is out there affecting the motions of stars and galaxies, but thus far, no one has been able to directly detect the substance—called dark matter—itself. But some are hoping that.

The supermassive black hole at the heart of the galaxy M87 is coming into sharper and sharper focus.

Four of the newfound quadruply imaged quasars are shown here: From top left and moving clockwise, the objects are: GraL J1537-3010 or “Wolf’s Paw;” GraL J0659+1629 or “Gemini’s Crossbow;” GraL J1651-0417 or “Dragon’s Kite;” GraL J2038-4008 or “Microscope Lens.” The fuzzy dot in the middle of the images is the lensing galaxy, the gravity of which is splitting the light from the quasar behind it in such a way to produce four quasar images. By modeling these systems and monitoring how the different images vary in brightness over time, astronomers can determine the expansion rate of the universe and help solve cosmological problems. Credit: The GraL Collaboration.

With the help of machine-learning techniques, a team of astronomers has discovered a dozen quasars that have been warped by a naturally occurring cosmic “lens” and split into four similar images. Quasars are extremely luminous cores of distant galaxies that are powered by supermassive black holes.

Over the past four decades, astronomers had found about 50 of these “quadruply imaged quasars,” or quads for short, which occur when the gravity of a massive galaxy that happens to sit in front of a quasar splits its single image into four. The latest study, which spanned only a year and a half, increases the number of known quads by about 25 percent and demonstrates the power of machine learning to assist astronomers in their search for these cosmic oddities.

Ultralight bosons are hypothetical particles whose mass is predicted to be less than a billionth the mass of an electron. They interact relatively little with their surroundings and have thus far eluded searches to confirm their existence. If they exist, ultralight bosons such as axions would likely be a form of dark matter, the mysterious, invisible stuff that makes up 85 percent of the matter in the universe.

Now, physicists at MIT’s LIGO Laboratory have searched for ultralight bosons using black holes—objects that are mind-bending orders of magnitude more massive than the particles themselves. According to the predictions of quantum theory, a black hole of a certain mass should pull in clouds of ultralight bosons, which in turn should collectively slow down a black hole’s spin. If the particles exist, then all black holes of a particular mass should have relatively low spins.

But the physicists have found that two previously detected black holes are spinning too fast to have been affected by any ultralight bosons. Because of their large spins, the black holes’ existence rules out the existence of ultralight bosons with masses between 1.3×10^-13 electronvolts and 2.7×10^-13 electronvolts—around a quintillionth the mass of an electron.

Black holes seemed to come only in sizes small and XXL. A new search strategy has uncovered a black hole of “intermediate” mass, raising hopes of more to come.

Humanity has come a long way in understanding the universe. We’ve got a physical framework that mostly matches our observations, and new technologies have allowed us to analyze the Big Bang and take photos of black holes. But the hypothetical EmDrive rocket engine threatened to upend what we knew about physics… if it worked. After the latest round of testing, we can say with a high degree of certainty that it doesn’t.

If you have memories from the 90s, you probably remember the interest in cold fusion, a supposed chemical process that could produce energy from fusion at room temperature instead of millions of degrees (pick your favorite scale, the numbers are all huge). The EmDrive is basically cold fusion for the 21st century. First proposed in 2001, the EmDrive uses an asymmetrical resonator cavity inside which electromagnetic energy can bounce around. There’s no exhaust, but proponents claim the EmDrive generates thrust.

The idea behind the EmDrive is that the tapered shape of the cavity would reflect radiation in such a way that there was a larger net force exerted on the resonator at one end. Thus, an object could use this “engine” for hyper-efficient propulsion. That would be a direct violation of the conservation of momentum. Interest in the EmDrive was scattered until 2016 when NASA’s Eagelworks lab built a prototype and tested it. According to the team, they detected a small but measurable net force, and that got people interested.

When we think about objects in space, like galaxies and black holes, our only frame of reference are the images we’ve seen, taken by the Hubble Space Telescope and similar instruments. Now, thanks to NASA’s new data sonification series, we can translate data signals of these objects into audio.

Michio Kaku is a professor of theoretical physics at City College, New York, a proponent of string theory but also a well-known populariser of science, with multiple TV appearances and several bestselling books behind him. His latest book, The God Equation, is a clear and accessible examination of the quest to combine Einstein’s general relativity with quantum theory to create an all-encompassing “theory of everything” about the nature of the universe.

The physicist on Newton finding inspiration amid the great plague, how the multiverse can unite religions, and why a ‘theory of everything’ is within our grasp.