Tag Archives: cosmology

Beginnings

13 November 2025 By in Physics, Science, Space Tags: , , , , , , , , , , , Leave a comment

A recent ScienceDaily write‑up titled “Scientists just found the hidden cosmic fingerprints of dark matter” suggests a breakthrough in the elusive substance that binds galaxies together. In reality, the study reports that Lyman‑Alpha emitters are a transient phenomenon, interesting, but nowhere near the revolutionary advance implied by the headline.

For readers uninitiated in cosmology and astrophysics, that’s a lot of jargon at once. So let’s bring it down a notch with some plain definitions.

Dark matter is the invisible mass that holds galaxies together through gravity. Without it, galaxies would fly apart. We infer its existence only because galaxies behave as they do. It makes up about 27% of the universe’s total energy density. By comparison, ordinary matter, the stuff we can see and measure, accounts for a measly 5%. Dark energy, the mysterious driver of cosmic acceleration, contributes about 68%. But that’s a story for another day.

Lyman‑Alpha emitters (LAEs) are distant, generally low‑mass galaxies that shine in Lyman‑alpha radiation: ultraviolet light produced when a hydrogen electron drops from the second energy level to the ground state (n=2 → n=1). Because this light is strongly redshifted by cosmic expansion, LAEs act as beacons of the early universe. Observing the ones implied in the opening science press headline means looking back to a time when the cosmos was less than a billion years old.

Scientists examine the clustering of LAEs across three epochs, each marking a milestone in cosmic evolution, a page from the manuscript of creation. At a redshift of 6, when the universe was about 0.9 to 1.0 billion years old, roughly 12.8 billion years ago, the first galaxies and stars were re‑ionizing neutral hydrogen, lifting the primordial fog and making the universe transparent. This period is known as the Epoch of Reionization.

The next epoch, at a redshift of 5.7 (about 100 million years later, or 12.7 billion years ago), is called the Late Reionization / Transition Epoch. Here, scientists measure how quickly the fog of neutral hydrogen dissipated and how galaxies began to cluster. Clustering serves as a proxy for the gravitational wells of dark matter, which drew in and anchored ordinary matter.

Finally, at a redshift of 3, around 11.8 billion years ago, the Post‑Reionization Epoch reveals a more mature universe with large‑scale structures taking shape. LAEs in this era trace galaxy clustering and help infer the masses of the dark matter halos they inhabit. These halos are vast, spherical envelopes of unseen matter surrounding galaxies and clusters.

With this groundwork, we return to the science press claim that researchers have found the “fingerprints” of dark matter itself. In truth, the fingerprints show no loops or swirls, no identification of what dark matter is or how it is distributed, only confirmation of what is already established. Without dark matter, galaxies would not exist. It is, in essence, a Cartesian maxim: I gather, therefore I am. Nothing more. Nothing less.

There was, however, a genuine insight. Lyman‑alpha emitters are transient, short‑lived luminous phases in galaxies that trace the framework of dark matter. The clustering function does not reveal dark matter’s nature; it just shows how rarely baryonic light, the real stuff of frogs, men, and cybertrucks aligns with gravitational tugs.

This raises a deeper question: why does dark matter clump at all, instead of remaining uniform across the cosmos? The answer lies in gravitational instability. Minute quantum fluctuations in the infant universe were stretched to cosmic scales by inflation, imprinting faint density variations, ripples in spacetime itself (if time exists is another a question for a different day). Cold, non‑interacting dark matter streamed into these wells, not merely seeking density but becoming it, deepening the imprints and laying the invisible scaffolding upon which galaxies and clusters would later rise. In turn, the growing clumps reinforced the very variations that seeded them, a feedback loop that sculpted the universe’s large‑scale structure. Quantum fractures first, dark matter responding.

And yet another knot: where did dark matter come from? If it does not interact, how could it be born from interaction? Perhaps it is not a product of the Big Bang at all. Did it exist outside the Bang, or was it a transformation from an earlier state?

Unto the spirit of dark energy, the expansive gust that stretches spacetime, accelerating the universe’s drift into an ever‑expanding horizon. If dark matter is transformation, is dark energy its continuation, or merely a phase toward dissolution?

Together they form a cosmic tension: cohesion and dispersal, gathering and vanishing. The Big Bang may not be the beginning, but only the first visible flare in a manuscript already dictated eons before the dawn.

In this reframing, baryonic matter: atoms, stars, flesh, machines, is a late arrival. Bone, blood, and silicone are ritual sparks, flaring briefly in the gravitational wells carved by dark matter and stretched by dark energy. We are not the fathers of the universe, but the children of a violent past.

Dark matter is the glue. Dark energy erases the image. We are but the punctuation; marks in a manuscript whose lines were written long before our arrival.

Source: …Fingerprints of Dark Matter, Science Daily, Sept. 2025. ODIN: Clustering Analysis… by Herrera et al, Astrophysical Journal Letters, 2025. Graphic: Lyman-Alpha Galaxy Up Close Illustration by M. Wiss, 2009. Public Domain

Shot in the Dark

21 September 2025 By in Physics, Science, Space Tags: , , , , , , , , , , , , , , , Leave a comment

The Earth orbits the Sun at a brisk 107,000 km/hr (66,486 mi/hr). The Sun, in turn, circles the Milky Way at a staggering 828,000 km/hr (514,495 mi/hr). And deep in the galactic core, stars whirl around the supermassive black hole at relativistic speeds, up to 36 million km/hr (22,369,363 mi/hr). Gravity is the architect and master of this motion: the invisible hand that not only initiates these velocities but binds our galaxy into a luminous spiral of unity.

Except it shouldn’t. Not with the piddling amount of mass that we can see.

The Milky Way contains 60-100 billion solar masses, an impressive sum, but a puny, gravitationally insufficient amount. With only that amount of ordinary matter, the galaxy would disperse like dry leaves in a breeze. Its stars would drift apart, its spiral arms dissolve, and the universe itself would remain a diffuse fog of light and entropy, never coalescing into structure or verse. No Halley’s Comet. No seasons. No Vivaldi.

To hold the Milky Way together at its observed rotation speeds requires about 1.4 trillion solar masses, seven times the visible amount. And we know this mass is there not because we’ve seen it, but because the galaxy exists. Much like Descartes’ Cogito, ergo sum (“I think, therefore I am”), we reason: The Milky Way is; therefore, it must possess sufficient mass.

The problem is that 85% of that mass is missing; from view, from touch, from detection. Enter stage right: Dark Matter. It does not emit, absorb, or reflect light. It does not interact with ordinary matter in any known way. It is invisible, intangible, a Platonic ether of shadow reality. Without it, the sacrament of gravity and being floats away like a balloon on a huff and puff day. And the universe loses its meaning.

Much like the neutrino, predicted by theory, is a particle once postulated to preserve the sanctity of conservation laws, a piece of the quantum world long before it was ever seen. Dark Matter is another elusive phantom, inferred by effect, but physically undetected. Dark Matter bends light, sculpts galaxies, and governs gravitational dynamics, yet it inhabits a metaphysical realm that requires faith to make it real. Unlike the neutrino, it lacks a theoretical platform. The General Theory of Relativity insists it must have mass; the Standard Model offers it no space. It is an effect without a cause: a gravitational fingerprint without a hand.

Yet, physicists are trying to tease it out, not so much to grasp a formless ghost, but rather to catch a glimpse of a wisp, a figment, without knowing how or where to look. To bring light to the dark one must grope around for a switch that may or may not exist.

Researchers at the University of Zurich and the Hebrew University of Jerusalem have devised an experiment called QROCODILE: Quantum Resolution-Optimized Cryogenic Observatory for Dark matter Incident at Low Energy (One can only guess at the amount of time and gin the Docs spent on that acronym 😊) to help tease out the existence of Dark Matter.

The experiment is designed to detect postulated ultralight dark matter particles that may interact with ordinary matter in currently unfathomable ways. To find these particles they have built a detector of superconducting nanowire sensors, cooled to near absolute zero, that achieves an astounding sensitivity to detect an infinitesimally small mass of 0.11 electron-volts (eV).

0.11 eV is roughly the energy difference between two quantum states in a molecule. An imperceptible shiver in the bond between two hydrogen atoms: a mass so slight, it might provoke a murmur of dark matter itself.

Using this detector over a 400-hour run (16.66 days) the team recorded a handful of unexplained signals that are real but not necessarily dark matter. Eventually they hope to achieve detections that resolve directionality, helping distinguish dark matter from background noise. The next phase of the experiment: NILE QROCODILE, (groan*) will move the detectors underground to reduce cosmic interference.

QROCODILE is a shot in the dark. It’s an epistemological paradox: how do you build a detector for something you don’t understand? How, or why, do you build an energy detector for a substance, if it is indeed a substance, that doesn’t emit or absorb energy.

While dark matter is known through its gravitational pull, that detection at a particle level is infeasible. Energy detectors, then, are a complementary strategy, betting on weak or exotic interactions beyond gravity.

Whether it finds Dark Matter or not, QROCODILE reminds us that science begins not with certainty, but with the courage to ask questions in the dark, and the craftsmanship to build instruments that honor the unknown.

* NILE QROCODILE: an acronym that evokes remembrance of the socially awkward Dr. Brackish Okun, a secluded researcher of aliens and their tech at Area 51 in the 1996 movie Independence Day.

Source: …Dark Matter Search with QROCODILE… by Laura Baudis et al, Physical Review Letters, 2025. Graphic: Nile Crocodile Head by Leigh Bedford, 2009. Public Domain.

To Boldly Go

20 July 2025 By in Physics, Science, Space Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , Leave a comment

On 23 June 2025, after more than three decades of evolution, from a gleam of an idea to detailed planning, exacting execution, and the physical realization of the world’s largest astronomical camera, the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) in Chile unveiled to the public its first breathtaking images. Among them: razor-sharp mosaics of the Trifid and Lagoon Nebulae, and the sprawling Virgo Cluster, home to millions of galaxies. Captured with world-class light-collecting mirrors, these images marked the beginning of a spectacular ten-year quest to map the known universe and illuminate the 95% we still don’t understand: dark matter and dark energy. An exciting, albeit, Herculean future awaits, built on an equally stunning past where dreams and science converged into one of the most staggering feats of technological achievement in modern astronomy.

Let the future map of the universe tell its own story in due time. The path to the map deserves a chapter all its own.

In 1969 Willard Boyle and George Smith of Bell Labs invented a device capable of detecting and measuring the intensity of light which they named CCD or Charge-Coupled Device: a breakthrough that earned them the 2009 Nobel Prize in Physics. A CCD converts incoming photons into electrical signals, creating a voltage map of light intensity, a digital proxy for the number of photons striking its surface. Initially constructed as a semiconductor chip, it quickly evolved into a pixelated imaging sensor. These sensors quickly became the gold standard for digital consumer and scientific imaging but due to costs, consumer applications such as your phone camera switched over to CMOS sensors due to lower costs. Scientific and surveillance systems, such as the Hubble Telescope, SOAR, and SNAP, still employ CCDs because of their superior image fidelity.

In the late 1980s J. Anthony ‘Tony’ Tyson, an experimental physicist at Bell Labs, focused on developing instrumentation to detect faint optical signals using CCDs. His inspiring contribution to the CCD was to recognize their potential in imaging the heavens and laying the groundwork for digital deep sky surveys. He quickly discovered faint blue galaxies and gravitational lensing using modified CCDs that he helped developed. Additionally, he helped build the Big Throughput Camera that was instrumental in the 1998 discovery of dark energy.

Tyson never thought small. His CCDs were instruments of the infinitesimal, but his dreams were as gargantuan as the universe itself. In fact, his dream was the universe. In 1994 he proposed his “Deep Wide Fast” telescope, a scaleup of his Big Throughput Camera and the forerunner of the LSST. The Deep Wide Fast was a concept that would combine a deep imaging device with rapid cadence, and broad coverage simultaneously. In other words, synoptic realization of the universe in near real time.

Throughout the 1990s, Tyson rallied minds and resources to shape his cosmic vision. John Schaefer of the Research Corporation helped secure early funding. Roger Angel proposed the use of the innovative Paul Baker three-mirror telescope design. Institutions like the Universities of Arizona and Washington, along with the Optical Astronomy Observatory, all hitched their wagons to Tyson’s star-filled dream of mapping the universe.

In 1998 Tyson presented designs for a Dark Matter Telescope and in 1999 the science case was submitted to the Astronomy and Astrophysics Decadal Survey. In 2003 the first formal proposal was sent to the Experimental Program Advisory Committee at SLAC (Stanford Linear Accelerator Center). It consisted of an 8.4-meter mirror with a 2.3-billion-pixel camera capable of surveying the entire visible sky every few nights. The proposal also laid out the NSF–DOE partnership, with SLAC leading the camera development and other institutions handling optics, data systems, and site operations.

In 2004 Tyson left Bell Labs and joined the University of California at Davis as a cosmologist and continued to shepherd the LSST project from there.

In 2007 the project received $30 million in private funding from Charles Simonyi, Bill Gates, and others. The telescope is named the Simonyi Survey Telescope. In 2010 U.S. National Science Foundation (NSF) and Department of Energy (DOE) joined in the quest to view the universe through the sharp eyes of the LSST.

The telescope’s primary 8.4-meter and the 5.0-meter tertiary mirrors were built at the University of Arizona, beginning in 2008, completed in 2015, and stored on-site in Chile since 2019. Fabricated in the U.S., the 3.4-meter secondary was later coated in Germany with nickel-chromium, silver, and silicon nitride, materials chosen to enhance reflectivity, durability, and long-term performance.

In 2015 SLAC, which oversaw the design, fabrication, and integration of the camera, began building the components with assistance from Brookhaven National Laboratory, Lawrence Livermore National Laboratory, and IN2P3/CNRS in France. By 2024 the camera was finished and shipped to Chile. In 2025 the camera was installed and integrated with the telescope. In June of 2025 the first light images were released to the public.

The camera measures roughly 3 meters in length, 1.65 meters in diameter, and weighs 3 metric tons, an imposing instrument, rivaling the bulk of a small car. Its imaging surface, a 64-centimeter focal plane, contains 3.2 billion pixels, each a 10-micron square, roughly one-tenth the width of a human hair. These pixels, etched across 189 custom CCD sensors arranged into 21 modular “rafts,” are laid flat to within 10 microns, ensuring near-perfect focus. The entire array is chilled to –100°C to suppress electronic and thermal noise, enhancing signal fidelity.

Before photons reach the sensor, they pass through three precision-crafted corrective lenses, including the largest ever installed in an astronomical camera, and up to six interchangeable filters spanning ultraviolet to near-infrared. The filter exchange system enables the observatory to target specific wavelength bands, tailored to sky conditions and science goals.

The integrated LSST system is engineered to capture a 15-second exposure every 20 seconds, producing thousands of images per night, tallying approximately 15 terabytes of new data. Each image covers 9.6 square degrees of sky, roughly equivalent to the diameter of 45 full moons, allowing the system to survey the entire visible southern sky every 3–4 nights. Imaging a single field across all six filters can take up to 5–6 minutes, though filters are selected dynamically based on science goals and atmospheric conditions.

The system’s angular resolution is sharp enough to resolve a golf ball from 15 miles away and at the edge of the observable universe, this scales to structures no smaller than a large galaxy; certainly not stars, not planets, nor restaurants. Over its decade-long campaign, LSST is projected to catalogue more than 17 billion stars and 20 billion galaxies, a composite digital universe stitched together from individual photons captured from 3 million images, each snapped every few seconds over the clear night sky of Chile. The LSST will not simply map what’s visible but illuminate the unknown. Beneath the sophisticated hardware and software lies a deeper purpose: to shine the light of curiosity on the 95% of the universe that remains in the shadows of time and space: dark matter and dark energy, the known unknown dynamic force behind galactic formation and cosmic expansion. The LSST is more than a camera. It is a reckoning with the vast unknown, a testament to humanity’s refusal to let mystery remain unexplored and uncharted: to find God.

In 2013 Tyson was named chief scientist of the LSST and is still actively contributing to the intellectual vision of the project and mentoring the next gen of cosmologists and engineers.

Graphic: LSST Camera Schematic and Trifid Nebula by SLAC-DOE-NSF.

Fate of the Universe

27 March 2025 By in Physics, Science, Space Tags: , , , , , , , , , , Leave a comment

Astronomers once observed exploding stars (supernovae) and found the universe expanding, driven by a mysterious force called dark energy. This led to the standard cosmological model of the late 1990s, Lambda-CDM, where “Lambda” represents dark energy, assumed constant, and “Cold Dark Matter” (CDM) explains unseen mass shaping cosmic structure. Evidence for CDM includes steady star rotation speeds in galaxies, cosmic microwave background fluctuations, galaxy clustering, and light bending by gravity. Though successful, Lambda-CDM has faced ongoing scrutiny almost from inception of the theory.

Enter the Dark Energy Spectroscopic Instrument (DESI) at Kitt Peak National Observatory in Arizona. With 5,000 robotic fiber-optic sensors, DESI captures light from galaxies and quasars, mapping the universe’s expansion history. A new study, analyzing three years of DESI data, 15 million objects, with plans for 50 million, combines it with cosmic microwave background radiation, supernovae, and weak gravitational lensing data. Fitting all this into Lambda-CDM with a constant dark energy revealed cracks in the model. But if dark energy weakens over time, a “dynamical dark energy“, the model aligns better.

By observing objects up to 11 billion years away, DESI peers deep into cosmic history. Researchers found hints that dark energy’s strength may have peaked around 7 billion years ago, then started weakening, challenging its fixed nature in Lambda-CDM. While not certain, this could rival the 1990s discovery of accelerated expansion, potentially demanding a new model.

The universe’s fate depends on dark energy versus matter. It’s been accelerating, but a weakening dark energy might slow it down, halt it, or, if gravity overtakes sufficiently, trigger a “Big Crunch.” New data from DESI, Europe’s Euclid, NASA’s Nancy Grace Roman, and Chile’s Vera Rubin Observatory could clarify this within five years, possibly nailing dark energy’s role.

Source: “Dark Energy Seems to Be Changing, Rattling Our View of Universe” by Rey and Lawler, Phys.org, March 2025. Graphic: DESI Collaboration Photo of Galaxies.