This Week in Astronomy: Hubble Crisis, Right-Handed Neutrinos and Water from First Stars

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a
<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for
<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky. This week in Astronomy, Hubble Crisis,
<v Speaker 1>right Handed, neutrinos, and water from First Stars. The Hubble
<v Speaker 1>Crisis rethinking the universe's expansion. The universe appears to be
<v Speaker 1>expanding at a rate faster than what theoretical models predict,
<v Speaker 1>challenging our current understanding of physics. This discrepancy, known as
<v Speaker 1>the Hubble tension, has been the subject of intense debate. Now,
<v Speaker 1>new results published in the Astrophysical Journal Letters reinforce the
<v Speaker 1>evidence for this faster rate of expansion, pushing the attention
<v Speaker 1>to what researchers are calling a crisis in cosmology. The
<v Speaker 1>expansion rate of the universe, called the Hubble constant, has
<v Speaker 1>been a focus of scientific investigation since Edwin Hubble's groundbreaking
<v Speaker 1>discovery in nineteen twenty nine that the universe is expanding.
<v Speaker 1>Dan Skalmik, a physicist at Duke University, likens this pursuit
<v Speaker 1>to constructing the universe's growth chart. While we understand the
<v Speaker 1>universe's size at the time of the Big Bang, there
<v Speaker 1>is still uncertainty about how it has grown to its
<v Speaker 1>current size. The distant universe representing the universe's baby picture
<v Speaker 1>in the local universe, akin to its current headshot, do
<v Speaker 1>not align when connected using the standard model of cosmology.
<v Speaker 1>This mismatch suggests that the widely accepted model of the
<v Speaker 1>universe may be flawed. To refine measurements of the Hubble constant,
<v Speaker 1>researchers rely on a cosmic distance ladder, a step wise
<v Speaker 1>method for measuring distances to celestion objects. Each rung on
<v Speaker 1>this ladder depends on the calibration of the previous one.
<v Speaker 1>A crucial breakthrough came when Skalnik used data from the
<v Speaker 1>Dark Energy Spectroscopic Instrument DESI, which observes over one hundred
<v Speaker 1>thousand galaxies nightly, to anchor the latter closer to Earth.
<v Speaker 1>The key to this improvement was obtaining a precise distance
<v Speaker 1>to the Coma cluster, a nearby galaxy cluster. Skalnik in
<v Speaker 1>his team used the light curves of twelve type IA
<v Speaker 1>supernova within the cluster. These supernova, often referred to as
<v Speaker 1>standard candles, have a predictable luminosity, making them reliable for
<v Speaker 1>measuring distances. Their calculations placed the Coma cluster at approximately
<v Speaker 1>three hundred and twenty million light years away, aligning with
<v Speaker 1>a range of distances reported over decades, reinforcing confidence in
<v Speaker 1>the result. Using this refined distance as the foundation, the
<v Speaker 1>team recalibrated the Cosmic day distance ladder and determined a
<v Speaker 1>Hubble constant value of seventy six point five kilometers per
<v Speaker 1>second per megaparsec. This value indicates that the universe expands
<v Speaker 1>by seventy six point five kilometers per second for every
<v Speaker 1>three point two six million light years of distance. While
<v Speaker 1>this measurement matches other recent observations of the local universe's expansion,
<v Speaker 1>it conflicts with predictions based on the distant universe and
<v Speaker 1>the standard cosmological model. This divergence raises a critical question
<v Speaker 1>is the problem with the measurements themselves or with the
<v Speaker 1>underlying theoretical models. According to Skalmik, the growing evidence points
<v Speaker 1>to the models being the issue. Over the years, numerous
<v Speaker 1>reanalyzes have been conducted, and despite changing methodologies, researchers consistently
<v Speaker 1>arrive at similar values for the Hubble constant. This consistency
<v Speaker 1>strongly supports the idea that the tension originates from a
<v Speaker 1>flaw on the model's rather than the measurements. The implications
<v Speaker 1>of this work are profound. The findings suggest that the
<v Speaker 1>cosmological models developed over the past twenty five years may
<v Speaker 1>need significant revision. Skalnik emphasizes that these results are pushing
<v Speaker 1>the boundaries of our understanding, signaling that there are still
<v Speaker 1>unknowns in the field of cosmology. This ongoing exploration may
<v Speaker 1>fundamentally reshape our understanding of the universe and open the
<v Speaker 1>door to new discoveries about its nature and origins. Right
<v Speaker 1>handed neutrinos unlocking cosmic mysteries. New research suggests that strange
<v Speaker 1>particles known as right handed neutrinos may hold the key
<v Speaker 1>to understanding why the universe is filled with matter instead
<v Speaker 1>of nothing, offering potential explanations for several long standing mysteries
<v Speaker 1>in physics. In the realm of fundamental interactions, most processes
<v Speaker 1>are symmetrical, producing equal amounts of matter and antimatter. Yet
<v Speaker 1>our universe contains primarily matter, with antimatter only appearing in rare,
<v Speaker 1>high energy events. This imbalance has puzzled scientists for decades,
<v Speaker 1>and right handed neutrinos might provide the answer. Neutrinos themselves
<v Speaker 1>are enigmatic particles. They exist in three types or flavors,
<v Speaker 1>and have extremely small masses. Unlike other particles, all known
<v Speaker 1>neutrinos are left handed, meaning their internal spins aligned in
<v Speaker 1>a specific direction as they move. This unique behavior sets
<v Speaker 1>them apart from other particles, which can have spins oriented
<v Speaker 1>in both directions. Physicists, however, suspect the existence of undiscovered
<v Speaker 1>right handed neutrinos, which would be much heavier than their
<v Speaker 1>left handed counterparts. In the early universe, when temperatures were
<v Speaker 1>incredibly high, both types of neutrinos could have interacted freely.
<v Speaker 1>As the universe expanded and cooled, a critical event symmetry
<v Speaker 1>breaking would have caused the heavy right handed neutrinos to
<v Speaker 1>become invisible to detection. This symmetry breaking might have separated
<v Speaker 1>matter from antimatter, resolving the imbalance that left the universe
<v Speaker 1>dominated by matter. The story of right handed neutrinos doesn't
<v Speaker 1>end there. Researchers propose that these particles may have given
<v Speaker 1>rise to a new entity called the major in. This
<v Speaker 1>hypothetical particle would be its own antiparticle and could still
<v Speaker 1>exist in the universe today as a relic from the
<v Speaker 1>early cosmos. Importantly, the major in might fit the description
<v Speaker 1>of dark matter, the elusive substance that makes up most
<v Speaker 1>of the mass and galaxies but has never been directly observed.
<v Speaker 1>If true, this hypothesis connects three major puzzles. Why all
<v Speaker 1>known neutrinos are left handed, why the universe contains more
<v Speaker 1>matter than antimatter, and what constitutes dark matter. While this
<v Speaker 1>idea remains theoretical, it offers there's an exciting avenue for
<v Speaker 1>further research. Discovering evidence for right handed neutrinos would not
<v Speaker 1>only reshape our understanding of neutrinos, but also help unravel
<v Speaker 1>the fundamental mechanisms shaping the universe's evolution. Such a breakthrough
<v Speaker 1>could bring us closer to solving some of the deepest
<v Speaker 1>mysteries in cosmology. Water from the first stars a cosmic legacy.
<v Speaker 1>Water is fundamental to life, and every living organism on
<v Speaker 1>Earth contains it. Earth's abundance of life is intrinsically tied
<v Speaker 1>to its abundance of water or relationships stemming from water's
<v Speaker 1>remarkable properties in its widespread presence in the universe. Composed
<v Speaker 1>of two hydrogen atoms bonded to one oxygen atom, water
<v Speaker 1>structure is both simple and robust. Hydrogen, the most abundant
<v Speaker 1>element in the cosmos, originated in the fiery aftermath of
<v Speaker 1>the Big Bang, while oxygen is produced in the nuclear
<v Speaker 1>furnaces of massive stars through the carbon nitrogen oxygen cno
<v Speaker 1>fusion cycle. Given this origin, scientists have generally believed that
<v Speaker 1>oxygen and consequently water, became more abundant over cosmic time.
<v Speaker 1>As generations of stars lived and died, they cast oxygen
<v Speaker 1>into space, enriching the universe with the ingredients for water.
<v Speaker 1>This progression implies that water was scarce in the early
<v Speaker 1>universe but became common in later epics. However, a new
<v Speaker 1>study challenges this assumption by suggesting that water may have
<v Speaker 1>been more abundant earlier than previously thought. Astronomers classify stars
<v Speaker 1>into populations based on their age and chemical composition. The
<v Speaker 1>youngest and most metal rich stars like the Sun, are
<v Speaker 1>categorized as population one. Older stars with fewer heavy elements
<v Speaker 1>are population two. The oldest stars, the first to form
<v Speaker 1>after the Big Bang, are known as Population three. These
<v Speaker 1>Population three stars, consisting solely of hydrogen and helium, were
<v Speaker 1>massive and short lived. Though they have not been directly observed,
<v Speaker 1>they played a pivotal role in shaping the universe, producing
<v Speaker 1>the first heavy elements and potentially the first water. The
<v Speaker 1>recent study modeled the explosive deaths of early stars, focusing
<v Speaker 1>on both massive two hundred solar masses and smaller thirteen
<v Speaker 1>solar masses stars. The massive Population three stars likely formed
<v Speaker 1>directly from primordial hydrogen helium clouds, while the smaller stars
<v Speaker 1>emerged in early stellar nurseries with very low metallicity. Upon
<v Speaker 1>their deaths, the smaller stars exploded as typical supernovae, while
<v Speaker 1>the massive stars underwent parents ability supernovae extremely energetic explosions
<v Speaker 1>unique to their size. Simulations suggest that these early stellar
<v Speaker 1>deaths significantly enrich their surrounding environments with water. The molecular
<v Speaker 1>clouds formed from their remnants contain water fractions ten to
<v Speaker 1>thirty times greater than those in diffuse molecular clouds within
<v Speaker 1>the Milky Way today. This enrichment implies that by one
<v Speaker 1>hundred to two hundred million years after the Big Bang,
<v Speaker 1>there may have been sufficient water in molecular clouds to
<v Speaker 1>potentially support the development of life. However, whether life emerged
<v Speaker 1>so early in the universe remains an open question. While
<v Speaker 1>water formed in significant amounts during this period, subsequent ionization
<v Speaker 1>and other astrophysical processes may have destroyed many of these molecules.
<v Speaker 1>The universe likely entered a dry phase before later generations
<v Speaker 1>of stars population two and I replenished water levels. Nevertheless,
<v Speaker 1>the study suggests that much of the water present in
<v Speaker 1>the universe today may trace its origins back to the
<v Speaker 1>first stars, making them a foundational source of this life
<v Speaker 1>sustaining molecule. This insight reshapes our understanding of water's cosmic
<v Speaker 1>history and its role in the potential emergence of life.
<v Speaker 1>Music a