Andromeda, Robotaxi Trouble, Custom LEDs, and Mental Health (Patreon)

Dark Energy Pushes Andromeda Away

Andromeda. Image: NASA

Astrophysicists at the University of Cambridge claim to have found a new way to measure dark energy by studying our galactic neighbor, Andromeda.

Andromeda is hurling towards our own Milky Way galaxy at about 250,000 miles per hour (112 kilometres per second). The two are predicted to collide in about four billion years. Their motion depends on the amount of visible matter, the amount of dark matter (if that exists), and the value of the cosmological constant, which is the simplest type of dark energy. From the observed velocity of the galaxies relative to each other, one can infer a bound on the value of the cosmological constant, which should have the effect of slightly counteracting the gravitational attraction between the galaxies.

In the new paper, the researchers found that with the best current mass estimate, the upper bound on the cosmological constant is about five times above the value from other observations, so at the moment it is not a very interesting finding. However, they say that if measurements improve, it could become yet another way to measure the cosmological constant. But given the large uncertainty on the masses involved, I have strong doubts it will ever become a very precise method.

Press release here, paper here.

Automated Vehicles Might Slow Down Traffic

Researchers at North Carolina State University say that self-driving vehicles slow down traffic if they cannot communicate with each other.

The group did computer simulations for 57 traffic situations and found that the higher the percentage of non-connected self-driving cars, the slower the travel time through intersections. The more of the self-driving cars were connected with each other, however, the more efficiently the traffic moved through intersections, eventually surpassing what human drivers could possibly achieve. The culprit, according to the researchers, is that self-driving cars are programmed to be extremely careful and that gives them a disadvantage in speed. If they are connected, however, they can make up for that disadvantage. Press release here, paper here.

This news won’t be news for the people of San Francisco, where a fleet of 10 robotaxies blocked an intersection for 15 minutes last week. According to the company, Cruise, a nearby music festival caused communication problems among the cars. We’ll know that they are truly self-aware once they start glueing themselves to the street.

Ballpoint Pen for Custom LEDs

Image: Zhao et al, Nature Photonics (2023)

Engineers at Washington University have developed colour pens for handwriting custom LEDs. The pens create a flexible and stretchable film on nearly any surface, including paper, textiles, rubber, and plastics. They can be connected to wires and be made to glow by switching a small current on and off.

Read more in the press release here or the paper here.