Enlarge / At critical pressures, the fluid's spheres become a mixture of different states. (credit: Adel Djellouli/Harvard SEAS )

Building a robot that could pick up delicate objects like eggs or blueberries without crushing them took lots of control algorithms that process feeds from advanced vision systems or sensors that emulate the human sense of touch. The other way was to take a plunge into the realm of soft robotics, which usually means a robot with limited strength and durability.

Now, a team of researchers at Harvard University published a study where they used a simple hydraulic gripper with no sensors and no control systems at all. All they needed was silicon oil and lots of tiny rubber balls. In the process, they’ve developed a metafluid with a programmable response to pressure.

Swimming rubber spheres

“I did my PhD in France on making a spherical shell swim. To make it swim, we were making it collapse. It moved like a [inverted] jellyfish,” says Adel Djellouli, a researcher at Bertoldi Group, Harvard University, and the lead author of the study. “I told my boss, 'hey, what if I put this sphere in a syringe and increase the pressure?' He said it was not an interesting idea and that this wouldn’t do anything,” Djellouli claims. But a few years and a couple of rejections later, Djellouli met Benjamin Gorissen, a professor of mechanical engineering at the University of Leuven, Belgium, who shared his interests. “I could do the experiments, he could do the simulations, so we thought we could propose something together,” Djellouli says. Thus, Djellouli’s rubber sphere finally got into the syringe. And results were quite unexpected.

Enlarge / Artist's visualization of GRB 221009A showing the narrow relativistic jets—emerging from a central black hole—that gave rise to the brightest gamma-ray burst yet. detected. (credit: Aaron M. Geller/Northwestern/CIERA/ ITRC&DS)

In October 2022, several space-based detectors picked up a powerful gamma-ray burst so energetic that astronomers nicknamed it the BOAT (Brightest Of All Time). Now they've confirmed that the GRB came from a supernova, according to a new paper published in the journal Nature Astronomy. However, they did not find evidence of heavy elements like platinum and gold one would expect from a supernova explosion, which bears on the longstanding question of the origin of such elements in the universe.

As we've reported previously , gamma-ray bursts are extremely high-energy explosions in distant galaxies lasting between mere milliseconds to several hours. There are two classes of gamma-ray bursts. Most (70 percent) are long bursts lasting more than two seconds, often with a bright afterglow. These are usually linked to galaxies with rapid star formation. Astronomers think that long bursts are tied to the deaths of massive stars collapsing to form a neutron star or black hole (or, alternatively, a newly formed magnetar ). The baby black hole would produce jets of highly energetic particles moving near the speed of light, powerful enough to pierce through the remains of the progenitor star, emitting X-rays and gamma rays.

Those gamma-ray bursts lasting less than two seconds (about 30 percent) are deemed short bursts, usually emitting from regions with very little star formation. Astronomers think these gamma-ray bursts are the result of mergers between two neutron stars, or a neutron star merging with a black hole, comprising a "kilonova." That hypothesis was confirmed in 2017 when the LIGO collaboration picked up the gravitational wave signal of two neutron stars merging, accompanied by the powerful gamma-ray bursts associated with a kilonova.

Enlarge / A visibly emotional Peter Higgs was present when CERN announced Higgs boson discovery in July 2012. (credit: University of Edinburgh )

Peter Higgs , the shy, somewhat reclusive physicist who won a Nobel Prize for his theoretical work on how the Higgs boson gives elementary particles their mass, has died at the age of 94 . According to a statement from the University of Edinburgh, the physicist passed "peacefully at home on Monday 8 April following a short illness."

“Besides his outstanding contributions to particle physics, Peter was a very special person, a man of rare modesty, a great teacher and someone who explained physics in a very simple and profound way," Fabiola Gianotti, director general at CERN and former leader of one of the experiments that helped discover the Higgs particle in 2012, told The Guardian . "An important piece of CERN’s history and accomplishments is linked to him. I am very saddened, and I will miss him sorely.”

The Higgs boson is a manifestation of the Higgs field, an invisible entity that pervades the Universe. Interactions between the Higgs field and particles help provide particles with mass, with particles that interact more strongly having larger masses. The Standard Model of Particle Physics describes the fundamental particles that make up all matter, like quarks and electrons, as well as the particles that mediate their interactions through forces like electromagnetism and the weak force. Back in the 1960s, theorists extended the model to incorporate what has become known as the Higgs mechanism, which provides many of the particles with mass. One consequence of the Standard Model's version of the Higgs boson is that there should be a force-carrying particle, called a boson, associated with the Higgs field.