One tough neutrino; time palindrome time; sizing up animal brains

How’s your weekend? Have you read about the muscular neutrino? It’s so great. This week, we also reported on male stick insects losing their reproductive function. Researchers are seeking cheaper approaches to creating a technology described by Scotty in “Star Trek IV.” And physicists explored the creation of a singularity-free black hole through pure gravity. Additionally, although I don’t want to swamp you with physics news, some theoreticians found evidence of two arrows of time in the quantum realm. And the complexity of birds’ brains evolved independently from mammals.

Neutron aggressive

Deep in the Mediterranean sea, researchers are building a massive installation called KM3Net, a telescope that will cover a cubic kilometer when construction is complete. It will have more than 6,000 sensors like the one pictured above, which detect neutrinos, the only particle that can reach those murky depths.

Neutrinos interact only very weakly with baryons and usually pass right through matter like electrically neutral ghosts, and most of them will travel right through the telescope and its sensors. But on extremely rare occasions, one of those neutrinos will collide with a water molecule and create a blue burst of energy the sensors can see.

Well, a few of the sensors are already up and running, and on February 13, 2023, KM3Net detected a neutrino 30 times more energetic than any previous observation, reported this week after two years of analysis.

The muscular neutrino was traveling at colossal speed and packed about 1 trillion times more energy than a medical X-ray. The researchers believe it originated from a source in the southern sky, and resulted from a massive cosmic event like a supernova or an active galactic nucleus. Unfortunately, KM3Net can’t accurately pinpoint the position and there are a lot of candidates in that region of space.

Time palindromic

Although the experience of time in a single direction seems obvious, the laws of physics do not favor a single direction. Many physical phenomena, like the movement of a pendulum, look the same whether you run a video forward or backward; physics does not account for irreversible processes, like liquid spilling across a table. In a new study, researchers at the University of Surrey explored whether the perception of time’s direction emerges from the quantum realm.

The researchers created a simplified model system in such a way that they could consider only the system itself and not the vast surrounding environment. And they assumed that, like the universe, energy and information would dissipate away into it, never to return (much like water spilling across a table). This allowed them to examine the one-way experience of time even though, at a quantum level, time can theoretically move in either direction.

“The surprising part of this project was that even after making the standard simplifying assumption to our equations describing open quantum systems, the equations still behaved the same way whether the system was moving forwards or backwards in time,” says Thomas Guff, first author of the publication.

Brains heterogeneous

In a series of studies, a multi-institutional research collaborative has determined that birds, mammals and reptiles evolved complex brains independently despite sharing a common ancestor. Although the three groups have brains with comparable functions, embryonic brain development and cell types all followed divergent evolutionary paths.

They focused on the embryonic development of the pallium, which in humans is responsible for distinctive cognitive processing functions. But although the functions of the pallium are similar for birds, mammals and reptiles, the developmental mechanisms and molecular identity of its neurons diverged substantially as the three groups evolved. Specifically, using spatial transcriptomics, the team determined that the neurons responsible for sensory processing are formed using different sets of genes.

Co-author Fernando García-Moreno says, “Our studies show that evolution has found multiple solutions for building complex brains. Birds have developed sophisticated neural circuits through their own mechanisms, without following the same path as mammals. This changes how we understand brain evolution.”

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