Lifeboat Foundation

The human middle ear—which houses three tiny, vibrating bones—is key to transporting sound vibrations into the inner ear, where they become nerve impulses that allow us to hear.

Embryonic and fossil evidence proves that the human middle ear evolved from the spiracle of fishes. However, the origin of the vertebrate spiracle has long been an unsolved mystery in vertebrate evolution.

Some 20th century researchers, believing that early vertebrates must possess a complete spiracular gill, searched for one between the mandibular and hyoid arches of early vertebrates. Despite extensive research spanning more than a century, though, none were found in any vertebrate fossils.

The human middle ear—which houses three tiny, vibrating bones—is key to transporting sound vibrations into the inner ear, where they become nerve impulses that allow us to hear.

Embryonic and fossil evidence proves that the human middle ear evolved from the spiracle of fishes. However, the origin of the vertebrate spiracle has long been an unsolved mystery in vertebrate evolution.

“These fossils provided the first anatomical and fossil evidence for a vertebrate spiracle originating from fish gills.” —

The structure of the universe is often described as being a cosmic web of filaments, nodes, and voids, with the nodes being clusters of galaxies, the largest gravitationally bound objects known. These nodes are thought to have been seeded by small-amplitude density fluctuations like those observed in the cosmic microwave background (CMB) which grew until they collapsed into the structures seen today. While the CMB is well understood, and the details of present-day galaxy clusters are well-described, the intermediate phases of evolution lack sufficient observations to constrain the models. Traditional galaxy cluster searches assume these objects have had enough time to equilibrate so that the intergalactic gas has heated up enough to be detected in X-ray emission. To detect the more distant galaxies and protoclusters that are too faint to detect in the X-ray, astronomers use their bright infrared or submillimeter emission instead.

The supercluster SPT2349−56, discovered in the submillimeter band by the South Pole Telescope, is so distant that its light has been traveling for over twelve billion years. It hosts over thirty submillimeter-bright galaxies and dozens of other luminous and/or spectroscopically confirmed star-forming galaxies. It is one of the most active star forming complexes known, producing over ten thousand stars per year. One of its bright sources appears to be the merger of over twenty galaxies. The stellar mass of the system, however, was not known, making it impossible for example to know whether the huge burst of stars was the result of an extraordinary efficiency or simply arose because the system was so extremely large.

CfA astronomer Matthew Ashby was a member of a team that has now completed very deep observations at optical and infrared wavelengths to obtain the stellar masses through spectral energy distribution (SED) analyses. They used the Gemini and Hubble Space Telescopes to obtain optical/near infrared flux measurements and Spitzer’s IRAC camera for the infrared flux. In order to model the SEDs, the many point sources detected need to be matched to one another at all wavelengths. This is a complex undertaking, and the scientists describe the processes for doing so while also addressing the serious blending that can occur due to inadequate spatial resolution in the infrared.

Why we need to adopt an abundance mindset.

Peter Diamandis shared an email blast about dire headlines that keep us on edge: the war in Ukraine, food and gasoline prices, climate change, and the neverending pandemic. Getting away from bad news is difficult, it appears, because of the way we are wired. Mass media feeds the bad far more than the good.

In his missive, Peter talks about Matt Ridley, a zoologist, who wrote and published The Rational Optimist in 2010. The book takes a profoundly optimistic view of human progress, a counterblast to the prevailing pessimism of our day. Ridley coined the phrase “moaning pessimism” to describe the current state.

Continue reading “From Pessimism to Optimism Despite the Headlines” »

The structure of how DNA is stored in archaea makes a significant difference to how quickly it evolves, according to a new study by Indiana University researchers.

The study, led by molecular biologist Stephen Bell, Distinguished Professor and chair of the College of Arts and Sciences’ Department of Molecular and Cellular Biochemistry at Indiana University (IU) Bloomington, was recently published in Nature Microbiology. Its findings have the potential to impact research on the treatment of genetic diseases such as cancer.

“The most exciting thing we revealed is the idea that the shape of a DNA molecule can affect its ability to change,” Bell said. “In the early 20th century, modernist architecture had the idea that the form of a building should follow its function. But what we’re seeing in these organisms is that over time, form is actually affecting evolution. How DNA is structured can change it, creating an evolutionary feedback loop.”

Though the planets are outside of their star’s habitable zone, as they orbit too closely, “there might be more planets in the system,” according to Avi Shporer, one of the scientists involved in the new study. “There are many multiplanet systems hosting five or six planets, especially around small stars like this one. Hopefully, we will find more, and one might be in the habitable zone. That’s optimistic thinking.”

Either way, the multiplanet system will likely be a focal point for future studies, shedding new insight into planetary formation and the evolution of alien worlds, helping the astronomical community better understand how our own planet came into existence.

The ancestors of some of the largest galaxy clusters have been hiding in plain sight. New work led by Carnegie’s Andrew Newman demonstrates a new technique for identifying the precursors of the most extreme galactic environments. The team’s findings are published in Nature.

Like all of us, galaxies are shaped and molded by their surroundings. To obtain a complete picture of the various physical influences on a galaxy’s lifecycle, it’s crucial to trace the emergence of properties caused by environmental factors as they arise.

“We’ve known for a long time that the colors, masses, and shapes of galaxies depend on their cosmic environment, but there’s a lot we don’t know about when and how those differences appeared,” Newman said.

A detailed analysis of the composition and motion of more than 500 stars has revealed conclusive evidence of an ancient collision between Andromeda and a neighboring galaxy. The findings, which improve our understanding of the events that shape galaxy evolution, were presented by Carnegie’s Ivanna Escala Monday at the meeting of the American Astronomical Society.

Galaxies grow by accreting material from nearby objects—other galaxies and dense clumps of stars called globular clusters —often in the aftermath of a catastrophic crash. And these events leave behind relics in the form of stellar associations that astronomers call tidal features. This can include elongated streams or arcing shells moving around the surviving galaxy. Studying these phenomena can help us understand a galaxy’s history and the forces that shaped its appearance and makeup.

“The remnants of each crash can be identified by studying the movement of the stars and their chemical compositions. Together this information serves as a kind of fingerprint that identifies stars that joined a galaxy in a collision,” Escala explained.

Circa 2021 Evidence of string theory by black holes as fuzzballs.

Abstract: We examine an interesting set of recent proposals describing a ‘wormhole paradigm’ for black holes. These proposals require that in some effective variables, semiclassical low-energy dynamics emerges at the horizon. We prove the ‘effective small corrections theorem’ to show that such an effective horizon behavior is not compatible with the requirement that the black hole radiate like a piece of coal as seen from outside. This theorem thus concretizes the fact that the proposals within the wormhole paradigm require some nonlocality linking the hole and its distant radiation. We try to illustrate various proposals for nonlocality by making simple bit models to encode the nonlocal effects. In each case, we find either nonunitarity of evolution in the black hole interior or a nonlocal Hamiltonian interaction between the hole and infinity; such an interaction is not present for burning coal. We examine recent arguments about the Page curve and observe that the quantity that is argued to follow the Page curve of a normal body is not the entanglement entropy but a different quantity. It has been suggested that this replacement of the quantity to be computed arises from the possibility of topology change in gravity which can generate replica wormholes. We examine the role of topology change in quantum gravity but do not find any source of connections between different replica copies in the path integral for the Rényi entropy. We also contrast the wormhole paradigm with the fuzzball paradigm, where the fuzzball does radiate like a piece of coal. Just as in the case of a piece of coal, the fuzzball does not have low-energy semiclassical dynamics at its surface at energies $E\sim T$ (effective dynamics at energies $E\gg T$ is possible under the conjecture of fuzzball complementarity, but these $E\gg T$ modes have no relevance to the Page curve or the information paradox).

From: Marcel Hughes [view email]