Lifeboat Foundation

Life’s evolutionary timescale is typically calibrated to the oldest fossil occurrences. However, the veracity of fossil discoveries from the early Archaean period has been contested^11,12. Relaxed Bayesian node-calibrated molecular clock approaches provide a means of integrating the sparse fossil and geochemical record of early life with the information provided by molecular data; however, constraining LUCA’s age is challenging due to limited prokaryote fossil calibrations and the uncertainty in their placement on the phylogeny. Molecular clock estimates of LUCA^13,14,15 have relied on conserved universal single-copy marker genes within phylogenies for which LUCA represented the root. Dating the root of a tree is difficult because errors propagate from the tips to the root of the dated phylogeny and information is not available to estimate the rate of evolution for the branch incident on the root node. Therefore, we analysed genes that duplicated before LUCA with two (or more) copies in LUCA’s genome¹⁶. The root in these gene trees represents this duplication preceding LUCA, whereas LUCA is represented by two descendant nodes. Use of these universal paralogues also has the advantage that the same calibrations can be applied at least twice. After duplication, the same species divergences are represented on both sides of the gene tree^17,18 and thus can be assumed to have the same age. This considerably reduces the uncertainty when genetic distance (branch length) is resolved into absolute time and rate. When a shared node is assigned a fossil calibration, such cross-bracing also serves to double the number of calibrations on the phylogeny, improving divergence time estimates. We calibrated our molecular clock analyses using 13 calibrations (see ‘Fossil calibrations’ in Supplementary Information). The calibration on the root of the tree of life is of particular importance. Some previous studies have placed a younger maximum constraint on the age of LUCA based on the assumption that life could not have survived Late Heavy Bombardment (LHB) (~3.7–3.9 billion years ago (Ga))¹⁹. However, the LHB hypothesis is extrapolated and scaled from the Moon’s impact record, the interpretation of which has been questioned in terms of the intensity, duration and even the veracity of an LHB episode^20,21,22,23. Thus, the LHB hypothesis should not be considered a credible maximum constraint on the age of LUCA. We used soft-uniform bounds, with the maximum-age bound based on the time of the Moon-forming impact (4,510 million years ago (Ma) ± 10 Myr), which would have effectively sterilized Earth’s precursors, Tellus and Theia¹³. Our minimum bound on the age of LUCA is based on low δ⁹⁸ Mo isotope values indicative of Mn oxidation compatible with oxygenic photosynthesis and, therefore, total-group Oxyphotobacteria in the Mozaan Group, Pongola Supergroup, South Africa^24,25, dated minimally to 2,954 Ma ± 9 Myr (ref. ²⁶).

Our estimates for the age of LUCA are inferred with a concatenated and a partitioned dataset, both consisting of five pre-LUCA paralogues: catalytic and non-catalytic subunits from ATP synthases, elongation factor Tu and G, signal recognition protein and signal recognition particle receptor, tyrosyl-tRNA and tryptophanyl-tRNA synthetases, and leucyl-and valyl-tRNA synthetases²⁷. Marginal densities (commonly referred to as effective priors) fall within calibration densities (that is, user-specified priors) when topologically adjacent calibrations do not overlap temporally, but may differ when they overlap, to ensure the relative age relationships between ancestor-descendant nodes. We consider the marginal densities a reasonable interpretation of the calibration evidence given the phylogeny; we are not attempting to test the hypothesis that the fossil record is an accurate temporal archive of evolutionary history because it is not²⁸.

Researchers at Cornell University have designed a novel in-suit urine collection and filtration system, or “Dune” system,” to “promote astronaut wellbeing.”

Welcome to Rethinking the Foundations brought to you by Curt Jaimungal at Theories of Everything. Today, Professor Neil Turok answers questions from the audience! This is Part 2 to Neil’s Rethinking the Foundations episode. Part 1 can be seen here: • Rethinking the Foundations of Physics…

Listen on Spotify: https://open.spotify.com/show/4gL14b9…

Continue reading “Q&A About the Universe with Top Physicist Neil Turok” »

An interplay of light and shadows cast the docking ports for Gateway, humanity’s first space station around the moon, into sharp relief.

Neutrinos have a quantum mechanical property called “flavor.” This flavor can transform as neutrinos move through space. A major challenge is to keep track of both the physical movement of the neutrinos and their change of flavor in astrophysical systems such as core-collapse supernovae and neutron star mergers. The complicated arrangement and large number of neutrinos in these systems make it nearly impossible to follow all or even a subset of the neutrinos.

Astronauts on spacewalks famously have to relieve themselves inside their spacesuits. Not only is this uncomfortable for the wearer and unhygienic, it is also wasteful, as—unlike wastewater on board the International Space Station (ISS)—the water in urine from spacewalks is not recycled.

“This shows that you need the water there in order to form these materials,” said Dr. Anthony Feldman. “But it needs to be cold, near-freezing mean annual temperature conditions in order to preserve the amorphous material in the soils.”

What was ancient Mars like? Was it warmer and wetter than it is today or cold and icy like present day Mars? This is what a recent study published in Communications Earth & Environment hopes to address as a team of researchers comprised of NASA scientists and academics investigated whether past climates on Mars mirrored today’s climate or were much warmer and had liquid water. This study holds the potential to help researchers better understand the climate history of Mars and whether it had the necessary conditions to support life as we know it.

For the study, the researchers analyzed X-ray data of soil material, which the researchers refer to as “X-ray amorphous material”, obtained from NASA’s Curiosity rover in Gale Crater on Mars and compared it to similar material at sites on Earth located in Newfoundland, California, and Nevada using the same X-ray methods employed by the Curiosity rover.

Continue reading “Similarities Between Mars Soils and Newfoundland’s Subarctic Climate” »

Engineers at EPFL have developed a device capable of transforming heat into electrical voltage efficiently at temperatures even colder than those found in outer space. This breakthrough could significantly advance quantum computing technologies by addressing a major obstacle.

To perform quantum computations, quantum bits (qubits) need to be cooled to temperatures in the millikelvin range (close to-273 degrees Celsius) to reduce atomic motion and minimize noise. However, the electronics used to control these quantum circuits generate heat, which is challenging to dissipate at such low temperatures. Consequently, most current technologies must separate the quantum circuits from their electronic components, resulting in noise and inefficiencies that impede the development of larger quantum systems beyond the laboratory.

Researchers in EPFL’s Laboratory of Nanoscale Electronics and Structures (LANES), led by Andras Kis, in the School of Engineering have now fabricated a device that not only operates at extremely low temperatures, but does so with efficiency comparable to current technologies at room temperature.

The idea of time travel has dazzled sci-fi enthusiasts for years. Science tells us that traveling to the future is technically feasible, at least if you’re willing to go near the speed of light, but going back in time is a no-go. But what if scientists could leverage the advantages of quantum physics to uncover data about complex systems that happened in the past?

New research indicates that this premise may not be that far-fetched. In a paper published June 27, 2024, in Physical Review Letters, Kater Murch, the Charles M. Hohenberg Professor of Physics and Director of the Center for Quantum Leaps at Washington University in St. Louis, and colleagues Nicole Yunger Halpern at NIST and David Arvidsson-Shukur at the University of Cambridge demonstrate a new type of quantum sensor that leverages quantum entanglement to make time-traveling detectors.

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