The investigation into dark energy; the origins of color blindness; the evolution of heads

It took the Dark Energy Survey an entire decade to produce a value for the cosmological constant – and it’s smaller than you think! There were other stories as well, including one about primitive black holes, and because I am inevitably drawn to the relentless seriousness of black hole news, it is included below, along with two other related stories from one way or another to the heads.

Insightful humans

Dogs’ primary sense is olfactory, and if their visual perception signals something interesting in the environment, the first thing they do is stick their cute little noses there. But the opposite is true for humans; we are capable of perceiving millions of colors, but only a fraction of the olfactory stimuli that dogs are typically overly involved with.

If you smell natural gas in your house, you search for the source with your cute little retinas and their ultra-dense constellation of photoreceptor cells to determine that one of the gas knobs on the stove is open. Researchers at Johns Hopkins University have grown retinal organoids in the laboratory to determine how human visual perception develops.

They found that retinoic acid determines whether a cone cell will specialize in detecting red or green light; the only species on the planet with visual perception of red light are humans and related primates.

Researchers found that high levels of retinoic acid early in development correlated with higher ratios of green cones, leading to red-green color blindness. Ultimately, researchers hope to apply findings derived from retinal organoids to treatments for macular degeneration, in which photoreceptor cells located in the center of the retina are lost.

Clarified heads

At some point in history, as vertebrates evolved, heads began to protrude. Theorists believe that either segmental elements of the trunk evolved into a skull or that the head evolved as a separate, unsegmented body part.

By studying the development of lampreys using advanced microscopy techniques, researchers at Fukui University have shed light on the origin of primitive head segments and mesoderm in vertebrates. In their study, they determined that the evolutionary mechanism for the development of head mesoderm was segregation between the front and rear elements in primitive organisms.

“Our results revealed a different evolutionary origin for vertebrate head mesoderm, suggesting that it evolved from the reconfiguration of ancient mesoderm and diversified even before the emergence of jawed vertebrates,” said Assistant Professor Takayuki Onai, one of the contributors.

Oversized holes

The James Webb Space Telescope and the relentless avalanche of data it has collected have provided insight into the primitive black holes at the centers of galaxies in the early universe, particularly the fact that they were much larger compared to the galaxies that existed in the early universe. They only occupied those of observable galaxies. the universe today.

There is a specific and predictable scaling relationship in the contemporary universe between supermassive black holes and the stellar populations they occupy that was different when the universe was young.

“We learned that young, distant galaxies violate the relationship between black hole mass and stellar mass that is very well established in nearby mature galaxies: these primitive black holes are undoubtedly overmassive compared to the stellar population of their hosts”, explains Roberto Maiolino. , professor at the University of Cambridge.

Calculated number

In this week’s most important physics event, the 10-year Dark Energy Survey announced its final measurement of a universal parameter called “w” – the equation of the state of energy black. Astronomers have known since the 1990s that not only is the universe expanding, but that the rate of expansion is increasing over time.

Since the force behind this acceleration is a mystery, physicists have called it “dark energy.” The value of the parameter “w” describes the relationship between pressure and energy density, and physicists believe that its value should be -1. The Dark Energy Survey used the same cosmic criteria that researchers used to detect accelerated expansion 25 years ago: Type Ia supernovae. But they had a much larger sample over a much larger area, and the data analysis yielded an aw value of… not quite -1.

In fact, they landed on -0.8, which is more precise than previous measurements, but with an uncertainty more in the realm of horseshoes and grenades than the actual value of the cosmological constant. Further studies using a larger sample size and decades of additional effort could produce a more precise value. As bad writers who can’t think of a kicker might write right before slumping in their chair and falling asleep: “Stay tuned!”

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