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In physics, an enormous question is sometimes asked in a very small region of spacetime:

How are quantum information and energy flow related at a local horizon?

Philipp Dorau and Albert Much study this question under carefully specified conditions. They consider a free scalar quantum field, first in the vacuum state and then in a coherent excitation. Roughly speaking, such an excitation can be pictured as a classical-like wave packet carried by the quantum field.

The key result is that the relative entropy between the vacuum and the coherent excitation can be related to the energy flux across a local Rindler horizon, weighted by the corresponding boost energy.

Relative entropy may be understood here as an information-theoretic measure of how distinguishable two quantum states are.

Why does this matter?

In quantum field theory, ordinary entanglement entropy for sharply bounded regions is often problematic. Local algebras of observables do not behave like finite-dimensional quantum systems described by ordinary density matrices.

Relative entropy, however, is well-defined in the algebraic framework. Modular theory also links the vacuum structure of the Rindler wedge to Lorentz boosts.

Does this prove that gravity comes from quantum information?

No. This is the most important limitation of the result.

Dorau and Much first establish a quantum-field-theoretic relation between relative entropy and energy flux. They then use the Bekenstein-Hawking entropy-area relation as an input to connect that flux to a change in horizon area. Through the Raychaudhuri equation, the area variation is related to spacetime curvature.

Together these steps reproduce the semiclassical Einstein equations. But the entropy-area relation is not independently derived by the paper; it is one of the essential assumptions. Spacetime geometry also remains classical while the matter field is treated quantum mechanically.

From Jacobson to quantum relative entropy

The result is nevertheless significant. In 1995, Ted Jacobson showed how Einstein's equations could be connected to a thermodynamic relation applied to local Rindler horizons. Dorau and Much show, in a concrete quantum-field-theory setting, how the "heat" and "entropy" in that argument can be replaced by energy flux and the well-defined Araki-Uhlmann relative entropy.

The paper therefore builds a precise bridge between quantum information and gravity — without yet explaining why spacetime itself should fundamentally emerge from information.

The work was published on 2 March 2026 in Physical Review Letters 136, 091602 (2026).

Connection to my own work

Although the work of Dorau and Much and my own work arrive at different results, they meet on the same mathematical and theoretical line. Modular theory, relative entropy, AQFT and Witten's crossed product are central concepts on this shared foundation.

Using these tools, Dorau and Much investigate how relative entropy can be connected to the semiclassical Einstein equations. My own work instead explores how modular geometry, physical accessibility and stable sectors within larger mathematical structures may be understood.

This is why my book sits directly within this discussion: it develops the mathematical language from Tomita–Takesaki theory to Witten's crossed product and examines the deeper background behind these questions. Our questions are different, but the theoretical horizon toward which they point is closely related.

MODULAR THEORY AND THE NEW LANGUAGE OF QUANTUM REALITY
From Tomita–Takesaki Theory to Witten's Crossed Product — On the Deep Structure of Reality, Time, and Information

If you follow these topics, ask questions, read my work and discuss these ideas, you are part of this journey too. Research ideas are shaped not only by published papers, but also by the people who examine them, challenge them and push them forward with new questions.

Arşen Kaan

Source

Philipp Dorau & Albert Much, "From Quantum Relative Entropy to the Semiclassical Einstein Equations", Physical Review Letters 136, 091602 (2026). DOI: 10.1103/lmq8-nsty.

Imagine travelling through completely empty space in a rocket that keeps accelerating uniformly.

Under idealised conditions, a detector in your hand would begin to respond as though it were immersed in a thermal bath of particles.

An observer moving inertially, however, could describe the same quantum state as vacuum.

Same spacetime. Different observers. Different particle descriptions.

This is the prediction known as the Unruh effect, introduced by William Unruh in 1976.

It has not yet been directly measured as a thermal bath seen by a uniformly accelerating detector.

For an acceleration comparable to Earth's gravitational acceleration, the predicted temperature is only about 4 × 10⁻²⁰ kelvin.

The real importance of the Unruh effect therefore lies not in its size, but in a much deeper question: What exactly is a particle?

What does the theory predict?

In quantum field theory, the vacuum is not simply "nothing." It is the lowest-energy state of a quantum field.

Whether a particular field excitation is interpreted as a particle depends on how the field is decomposed into positive- and negative-frequency modes. That decomposition can depend on the observer's motion.

An inertial observer and a uniformly accelerated observer naturally use different notions of time evolution. For the accelerated observer, one often introduces Rindler time.

This leads to a different mode decomposition. The striking result is that a state described as vacuum by an inertial observer can appear to a uniformly accelerated observer as a thermal distribution of particles.

The Unruh temperature is T = ħa / (2πck_B), where a is the acceleration.

Why is this so deep?

A uniformly accelerated observer can never access part of Minkowski spacetime. From that observer's perspective, a Rindler horizon appears.

This is mathematically related to the situation outside a black hole, where an external observer cannot access the region beyond the event horizon.

A global quantum state may be pure. But if an observer has access to only part of the system, the inaccessible degrees of freedom must be traced out. The remaining state can then appear mixed and may display thermal properties.

This is one reason the Unruh effect and Hawking radiation are mathematically related. They are not the same phenomenon, but both involve quantum fields, horizons and the portion of spacetime accessible to an observer.

The hidden clock

The Tomita–Takesaki theory shows that an appropriate von Neumann algebra together with a suitable state possesses a natural one-parameter group of automorphisms. This evolution is called modular flow.

In one famous special case, the Bisognano–Wichmann theorem shows that for the vacuum of a relativistic quantum field theory restricted to a Rindler wedge, modular flow is geometrically related to Lorentz boosts.

An abstract dynamics arising from operator algebra therefore coincides, in this particular setting, with a familiar spacetime symmetry.

In 1994, Alain Connes and Carlo Rovelli pushed this idea further with the Thermal Time Hypothesis. According to this proposal, in generally covariant theories the physically relevant notion of time evolution might, under certain circumstances, emerge from the state of the system itself.

This remains a hypothesis, not an experimentally established theory of time.

From Tomita–Takesaki to Witten

Modular structures also play an important role in modern discussions of entropy, horizons and quantum gravity.

In his paper "Gravity and the Crossed Product," Edward Witten examined how crossed-product constructions can be used in gravitational settings.

Local algebras in quantum field theory are typically Type III von Neumann algebras. Such algebras do not possess the ordinary trace familiar from finite-dimensional quantum mechanics, which makes conventional entropy definitions difficult.

Under suitable conditions, a crossed product can produce a related Type II structure for which a trace can be defined.

This provides a more controlled mathematical framework for discussing entropy in gravitational systems. Witten's crossed-product framework is not a complete theory of quantum gravity.

What these ideas do not prove

They do not prove that time does not exist, that particles are merely illusions, that spacetime is entirely made of information, that the Thermal Time Hypothesis has been experimentally confirmed, or that crossed products already solve quantum gravity.

The Unruh effect is regarded as a robust theoretical prediction of quantum field theory, but direct experimental detection remains extremely challenging.

Modular theory and crossed products instead provide a powerful mathematical language connecting quantum fields, entropy, entanglement, horizons and gravity.

The big question

If what we call a "particle" can depend on the observer, and if a relevant notion of time evolution can, in some settings, be connected to the state and algebra of a quantum system, then a fundamental question emerges:

What is the deepest language of reality?

Particles? Fields? Information? Or modular structure?

This is precisely the question explored in the book "Modular Theory and the New Language of Quantum Reality — From Tomita–Takesaki Theory to Witten's Crossed Product."

Arşen Kaan

Primary sources

William G. Unruh, "Notes on black-hole evaporation", Physical Review D 14, 870 (1976). DOI: 10.1103/PhysRevD.14.870.

Edward Witten, "Gravity and the Crossed Product", Journal of High Energy Physics 10 (2022) 008. arXiv:2112.12828.

Alain Connes & Carlo Rovelli, "Von Neumann algebra automorphisms and time-thermodynamics relation in generally covariant quantum theories", Classical and Quantum Gravity 11 (1994).

When I published my book in July 2026, I had already devoted a full chapter to IceCube. Today Francis Halzen received the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos from astrophysical sources. This shows just how current and important this field of research is.

The Royal Swedish Academy of Sciences awarded Francis Halzen the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube Neutrino Observatory and to the discovery of high-energy neutrinos of astrophysical origin.

IceCube is one of the most unusual observatories in modern physics. Thousands of optical sensors buried deep in Antarctic ice detect tiny flashes of light produced when neutrinos interact with matter.

These nearly invisible particles can carry information from some of the most extreme environments in the universe, including regions from which light may have difficulty escaping.

This is why I devoted a section of my book to IceCube. The topic appears in Chapter 10.9 of the July 2026 edition.

The chapter discusses high-energy cosmic neutrinos, their possible sources, and an unexpected break in the measured neutrino spectrum. That spectral feature is an open research question and is not the reason for the Nobel Prize.

Why IceCube matters

Neutrinos interact only very weakly with matter. That makes them extremely difficult to detect, but it also makes them uniquely valuable cosmic messengers.

IceCube opened a new observational window in high-energy astrophysics and helped establish neutrino astronomy as an important part of multi-messenger astronomy.

Already in the book

IceCube is only one part of the journey. The book also explores quantum physics, black holes, spacetime, information, gravity and the limits of our current understanding of reality.

The English edition is coming after Christmas 2026.

Arşen Kaan

Sources

Royal Swedish Academy of Sciences, Nobel Prize in Physics 2026: Francis Halzen.

University of Wisconsin-Madison: Francis Halzen named 2026 Nobel laureate in physics.

Located about 1,300 light-years away, WASP-17b is an extremely inflated hot Jupiter orbiting close to its star. Using James Webb Space Telescope transit observations, researchers have shown that its atmosphere does not reach the same height all the way around the planet.

The team measured a cooler morning limb at about 858 K and a hotter evening limb at about 1,522 K, corresponding to an east-west contrast of roughly 650–660 K. Because hotter gas has a larger scale height, the evening side appears more extended or "puffier."

Webb did not photograph a solid planetary surface. The map was reconstructed from tiny wavelength-dependent changes in starlight while WASP-17b crossed in front of its star.

How the mapping works

The study applied a method called transmission strings. Instead of forcing the entire atmospheric limb into one averaged radius, the method extracts spectra at different angles around the planet. The observations span roughly 0.6 to 12 micrometres using JWST instruments including NIRISS, NIRSpec and MIRI.

This makes it possible to probe variations not only between the morning and evening terminators, but also around the limb toward the poles and equator.

What is in the atmosphere?

The analysis constrains water vapour and carbon dioxide abundances to broadly constant values around the limb, while the temperature and atmospheric scale height change substantially.

That distinction is important: a planet can have similar chemistry across regions while still possessing strong temperature gradients, winds and changing atmospheric thickness.

Why it matters

Exoplanet atmospheres are genuinely three-dimensional. This work moves beyond a single averaged atmospheric value and toward spatially resolved weather and circulation measurements on worlds many light-years away.

Scientific status: peer-reviewed and published open access in Nature Astronomy on 14 October 2026.

Editorial preparation: Arşen Kaan

Primary source

Lili Alderson et al., "A spatial map of the atmospheric limb of a hot Jupiter," Nature Astronomy (2026). DOI: 10.1038/s41550-026-02986-4.

James Webb's "little red dots" are compact red sources that are common in the early Universe but become much rarer at later cosmic times. A new study asks whether the changing environments of these objects can help explain that decline.

The authors analysed 98 spectroscopically confirmed LRDs between redshifts 3 and 7. At redshifts above 4, the objects predominantly occupy under-dense regions. By around redshift 3.5, they are found in environments more typical of ordinary galaxies.

Cross-correlation measurements indicate that the characteristic dark-matter halo mass increases from roughly 10^10.1 solar masses at very high redshift to about 10^11.3 solar masses by redshift 3.5, approaching halo masses of more normal galaxies.

At higher redshift, LRDs appear to host black holes that are unusually massive compared with their stellar populations. At lower redshift, that relationship moves closer to the black-hole–stellar-mass relation measured in nearby galaxies.

The study does not track individual little red dots through time, and it does not settle what these objects physically are. The comparison is between populations at different epochs, and the underlying small-scale mechanism remains unknown.

Editorial preparation: Arşen Kaan

Primary source

Chenxuan Zhang, Huanian Zhang, Qingwen Wu, Luis C. Ho, Jian-Min Wang et al., "Reduced incidence of little red dots at z < 3 based on number density and halo mass evolution," Nature Astronomy (2026). DOI: 10.1038/s41550-026-03001-6.

Voyager 1 launched on 5 September 1977 and transformed our view of Jupiter and Saturn before continuing outward on an interstellar trajectory.

On 25 August 2012, measurements showed that Voyager 1 had crossed the heliopause, the boundary where the outward solar wind gives way to the surrounding interstellar medium. It became the first spacecraft to enter interstellar space.

The phrase "edge of the Solar System" depends on which boundary is meant. The heliopause marks the end of the Sun's solar-wind bubble, but far beyond it lies the hypothesised Oort Cloud, a vast reservoir of icy bodies still gravitationally associated with the Sun.

NASA estimates that Voyager 1 will not reach the inner edge of the Oort Cloud for about 300 years and could take roughly 30,000 years to pass beyond its outer edge.

So two statements can both be correct: Voyager 1 is in interstellar space, and Voyager 1 has not yet reached the Oort Cloud.

A Film by Arşen Kaan

Source

NASA Solar System Exploration, Oort Cloud facts; NASA/JPL Voyager mission information.

Many molecules come in two mirror-image forms called enantiomers. They contain the same atoms, but their three-dimensional geometry is reversed — much like left and right hands.

Henri Kagan's work helped establish that asymmetric catalysis does not always behave linearly. In some systems, a modest enantiomeric excess in the catalyst can produce a much larger imbalance in the product.

Kenso Soai demonstrated a landmark form of asymmetric autocatalysis in which a chiral product helps catalyse the formation of more product with the same handedness. Repeated reaction cycles can amplify a tiny initial imbalance into very high optical purity.

This chemistry provides an experimentally demonstrated mechanism by which symmetry breaking can be amplified, but it does not prove that the same reaction produced biological homochirality on the early Earth.

By Arşen Kaan

Source

Nature coverage of the 2026 Nobel Prize in Chemistry, 7 October 2026.

The story of optogenetics begins with light-sensitive proteins found in microorganisms such as the green alga Chlamydomonas.

Peter Hegemann and Georg Nagel carried out foundational work on channelrhodopsins — light-gated ion channels that can change a cell's electrical state when illuminated. Karl Deisseroth and collaborators then helped turn these molecular tools into a method for controlling genetically defined neurons with light.

Optogenetics allows researchers to selectively activate or inhibit defined neural circuits and test whether those circuits causally influence behaviour or physiology.

In animal models, the method has been used to investigate memory, reward, motivation, addiction, pain and many other brain functions with exceptionally high temporal precision.

Clinical use remains limited and experimental. One prominent direction is vision restoration, where light-sensitive proteins are introduced into retinal cells in attempts to restore aspects of visual perception in people with severe retinal degeneration.

Optogenetics is not a routine method for controlling individual neurons in the human brain. Its greatest impact so far has been as a research technology that transformed how neural circuits can be tested.

By Arşen Kaan

Sources

Nature, Stanford Medicine and the American Physiological Society, 5 October 2026.

What if your memories never happened?

What if an observer could appear complete with memories of a past that never actually occurred?

This unsettling possibility lies behind the Boltzmann Brain paradox.

In the nineteenth century, Ludwig Boltzmann helped establish the statistical interpretation of thermodynamics and strongly defended the atomic picture of matter. The formula now associated with his name is commonly written as S = k ln W, where entropy is related to the number of microscopic configurations compatible with a macroscopic state.

Entropy is often described loosely as "disorder," but the more precise idea is multiplicity: macrostates corresponding to vastly more microscopic arrangements have larger Boltzmann entropy and are statistically more typical.

From rare fluctuations to a paradox

In systems near thermal equilibrium, small statistical fluctuations can occur. In some cosmological models that persist for extraordinarily long times, one can then ask whether much rarer fluctuations might also occur.

A particularly extreme hypothetical fluctuation is a self-aware observer that appears with an apparently complete set of memories, despite having no ordinary evolutionary or cosmological history behind those memories.

Such a hypothetical observer is called a Boltzmann Brain.

No Boltzmann Brain has ever been observed. The concept is not an experimental discovery. It is a consistency test applied to cosmological theories and their treatment of probability, equilibrium and observers.

Why cosmologists take the problem seriously

The core issue is not whether a single Boltzmann Brain is logically imaginable. The problem arises when a theory predicts that observers produced by rare equilibrium fluctuations should vastly outnumber ordinary observers who arise through a long, low-entropy cosmic history.

If a cosmological model predicts that a typical observer should have unreliable memories and no coherent past, while our observations reveal a stable world with consistent records and a deep cosmic history, that model faces a serious explanatory problem.

This is why Boltzmann Brains are often used as a diagnostic for cosmological measures, de Sitter vacua, recurrence scenarios and theories of the arrow of time.

What the paradox does not prove

The Boltzmann Brain argument does not prove that reality is an illusion, that your memories are false, or that consciousness can literally pop into existence in our Universe.

Different cosmological frameworks treat the issue differently, and some analyses argue that Boltzmann Brain production is much less generic than earlier discussions suggested.

The lesson is more modest but profound: a successful cosmology must explain why ordinary observers with a coherent thermodynamic past are typical enough to make our observations unsurprising.

Boltzmann's deepest legacy is therefore not simply a formula. It is the realization that probability, entropy and microscopic multiplicity are central to understanding why the macroscopic world looks the way it does.

ARŞEN KAAN SCIENCE
SCIENCE FIRST. CURIOSITY ALWAYS.

Sources

Sean M. Carroll, "Why Boltzmann Brains Are Bad," arXiv:1702.00850 (2017).

Kimberly K. Boddy, Sean M. Carroll & Jason Pollack, "Why Boltzmann Brains Don't Fluctuate Into Existence From the De Sitter Vacuum," arXiv:1505.02780 (2015).

Stanford Encyclopedia of Philosophy, "Boltzmann's Work in Statistical Physics," revised 2024.

Black-hole entropy is famously proportional to horizon area, but ordinary local quantum-field algebras are typically Type III and do not possess the ordinary trace used in the familiar von Neumann entropy formula.

In 2022, Edward Witten studied how the modular automorphism group can be used to form a crossed product. In the setting he analysed, the emergent Type III₁ algebra becomes a Type II_∞ algebra after the relevant gravitational corrections are included.

The key mathematical advantage is that Type II algebras admit an appropriate trace structure. This permits the entropy of suitable black-hole states to be defined up to a state-independent additive constant.

This is not an experimental discovery of black-hole microstructure and it does not by itself solve the black-hole information paradox. It is a controlled algebraic framework showing how gravity can change which observable algebra is appropriate for entropy.

Arşen Kaan Science | Science Editorial

Primary source

Edward Witten, "Gravity and the Crossed Product," Journal of High Energy Physics 2022, 008 (2022). DOI: 10.1007/JHEP10(2022)008.

In 1998, the Super-Kamiokande Collaboration reported compelling evidence that atmospheric neutrinos change flavour while travelling. Oscillations require nonzero differences between neutrino mass eigenstates, so at least two neutrino mass eigenstates must have nonzero mass.

Oscillation experiments determine mass-squared differences and mixing parameters rather than the absolute mass of each neutrino.

One influential theoretical explanation is the seesaw mechanism. In a common Type-I model, the known light neutrinos mix with additional heavy neutral fermions. In a simplified one-generation limit, the light mass behaves approximately as mν ≈ mD² / MR.

The heavy states required by specific seesaw models have not been confirmed. Whether neutrinos are Dirac or Majorana particles also remains experimentally unresolved.

DUNE, Hyper-Kamiokande and JUNO will test complementary aspects of neutrino mixing, mass ordering and possible CP violation.

Arşen Kaan Science | Science Editorial

Primary sources

Fukuda, Y. et al. (Super-Kamiokande Collaboration), Physical Review Letters 81, 1562–1567 (1998). DOI: 10.1103/PhysRevLett.81.1562.

Mohapatra, R. N. & Senjanović, G., Physical Review Letters 44, 912–915 (1980). DOI: 10.1103/PhysRevLett.44.912.

The team compared six compact star-forming galaxies spanning different starburst ages using medium-resolution ultraviolet spectroscopy.

Systems younger than about 3 Myr showed higher escape fractions of ionizing Lyman-continuum radiation. More evolved systems showed faster outflows, larger equivalent widths and more dust, together with lower ionizing-photon escape.

The proposed explanation is mass loading: as a supernova-driven wind develops, it can sweep up additional gas and dust that absorbs ionizing photons rather than simply clearing a transparent channel.

The result is important for models of cosmic reionization, but the limitations matter. The sample contains only six local galaxies, the observed trend is a correlation, and different winds under different physical conditions may also help photons escape.

Arşen Kaan Science | Science Editorial

Primary source

Carr, C., Cen, R., McCandliss, S. et al. (2026). Lyman continuum escape during the onset of galactic winds in compact starbursts. Nature Astronomy. DOI: 10.1038/s41550-026-02999-z.

Earth is a tiny part of the Solar System. The Solar System is one small component of the Milky Way. And the Milky Way itself sits within the vast large-scale structure of the Universe.

Galaxies are not scattered randomly. Gravity organizes matter into groups, clusters, filaments and walls separated by enormous under-dense voids. Together these features form the cosmic web.

1. The Milky Way: our galactic home

The Milky Way is a barred spiral galaxy. Its stellar disk is approximately 100,000 light-years across, although its halo and outer components extend much farther.

The Solar System is located roughly 26,000 light-years from the Galactic Centre. The Milky Way is also a member of the Local Group together with Andromeda, Triangulum and many dwarf galaxies.

2. Laniakea: a 520-million-light-year flow region

In 2014, R. Brent Tully and colleagues used galaxy peculiar velocities — motions remaining after subtracting the overall expansion of the Universe — to reconstruct the local velocity field.

They identified a region about 520 million light-years across in which galaxy-flow trajectories converge toward a common gravitational basin. They named this region Laniakea.

Laniakea is not best understood as one rigid, gravitationally bound object in which every galaxy will ultimately merge. Its boundary depends on how the velocity field is reconstructed.

A 2024 Cosmicflows-4 analysis found a slight probabilistic preference for the Milky Way's larger basin of attraction to be associated with the much larger Shapley basin. This does not erase Laniakea; it shows that flow-defined boundaries can change as the data improve.

3. The Hercules–Corona Borealis Great Wall candidate

A remarkably large concentration in the direction of Hercules and Corona Borealis has been discussed on a characteristic scale of roughly 10 billion light-years.

This candidate was not discovered by directly imaging one continuous wall of galaxies. The evidence comes mainly from the spatial distribution of gamma-ray bursts with measured distances.

4. The 2026 reanalysis: 542 bursts and a 125-GRB overdensity

A paper published on 30 April 2026 in Monthly Notices of the Royal Astronomical Society reanalysed 542 gamma-ray bursts with spectroscopic redshifts using a three-dimensional spatial-density method.

In the Northern Galactic hemisphere, the strongest overdense region contained about 125 GRBs. Its angular distribution was consistent with the region previously associated with the Hercules–Corona Borealis Great Wall.

The authors estimated a probability of roughly 0.0007 to 0.0043 for obtaining such a clustering by chance under their resampling procedure.

That is evidence for a statistically significant GRB overdensity. It is not the same thing as directly proving one continuous, gravitationally connected wall of galaxies with sharply defined boundaries.

5. Is Laniakea inside the Great Wall?

There is no established result showing that.

The Milky Way's association with Laniakea comes from the reconstructed velocity field of the nearby Universe. The Hercules–Corona Borealis candidate comes from the statistical distribution of much more distant gamma-ray bursts.

So the popular visual hierarchy "Milky Way → Laniakea → Hercules–Corona Borealis Great Wall" should not be presented as a verified physical nesting relationship. The defensible comparison is one of scale, not confirmed membership.

6. Why do structures become so large?

In the standard cosmological picture, tiny density fluctuations in the early Universe grew under gravity. Dark matter played a central role in building the large-scale scaffolding along which gas, galaxies and clusters later accumulated.

The result is the cosmic web of filaments, clusters, sheets and voids seen in surveys and reproduced by cosmological simulations.

On sufficiently large scales, the Universe is expected to approach statistical homogeneity. That is why exceptionally large structure candidates must be tested carefully against survey selection effects, statistical fluctuations and the predictions of cosmological models.

7. A scale comparison

Milky Way stellar disk: about 100,000 light-years.

Laniakea: about 520 million light-years.

Hercules–Corona Borealis Great Wall candidate: about 10 billion light-years.

Laniakea is roughly 5,200 times wider than the commonly quoted diameter of the Milky Way's stellar disk. The quoted Great Wall scale is about 19 times larger than Laniakea in linear extent.

These are characteristic dimensions, not verified nested physical boundaries.

Conclusion

The Milky Way is a galaxy about 100,000 light-years across. Laniakea is a nearby flow-defined region on a scale of hundreds of millions of light-years. The Hercules–Corona Borealis Great Wall is a much more distant, enormously large candidate overdensity traced primarily by gamma-ray bursts.

The most important lesson is not simply how large these structures are, but that they are defined by different observational methods and do not all carry the same level of physical certainty.

Editorial preparation: Arşen Kaan

Primary scientific sources

Tully, R. B., Courtois, H., Hoffman, Y. & Pomarède, D. (2014). The Laniakea supercluster of galaxies. Nature 513, 71–73. DOI: 10.1038/nature13674.

Valade, A. et al. (2024). Identification of basins of attraction in the local Universe. Nature Astronomy 8, 1610–1616. DOI: 10.1038/s41550-024-02370-0.

Horvath, I. et al. (2026). Reanalysing large-scale structure using an updated gamma-ray burst spatial density approach. MNRAS 548(3), stag666. DOI: 10.1093/mnras/stag666.

For more than a century, The Starry Night has often been discussed as a work shaped primarily by imagination, memory and artistic transformation.

A new multidisciplinary study now argues that at least part of its celestial layout may have been grounded in a real sky.

The paper, published on 22 October 2026 in Scientific Reports, reconstructs the historical sky above Saint-Rémy-de-Provence and compares the geometry of the stars in the painting with actual stellar configurations.

The V-shaped clue

The researchers focused on a group of five prominent stars in the central portion of the painting that form a loose V-shaped pattern.

Using Procrustes shape analysis, they compared the geometry of the painted stars with real stellar patterns after allowing for changes in position, scale and rotation.

The strongest match identified in the study was the Hyades star cluster in Taurus.

The authors report that the geometric correspondence is especially compelling because the same pattern also appears in a pen drawing Van Gogh made after the painting.

Why July 22, 1889?

The team reconstructed the sky visible from the Saint-Rémy landscape before dawn during the summer of 1889.

They found that around 3:00 a.m. on July 22, 1889, a waning crescent Moon, Venus and the Hyades occupied positions that produced a composition broadly similar to the painting.

The study notes that only a small number of dates in June and July placed both the Moon and Venus inside the relevant field of view in a compatible arrangement.

Historical checks

Astronomy alone cannot date a painting conclusively, so the researchers also examined historical context.

They considered Van Gogh's letters, earlier sketches and local weather records. The authors argue that the sky conditions and the artist's known interest in pre-dawn observation are consistent with a late-July observation.

However, the conventional art-historical dating of The Starry Night remains around mid-June 1889, in part because Van Gogh wrote to his brother Theo around 18 June that he had completed a new study of a starry sky.

What the study does not prove

The new analysis does not establish beyond doubt that Van Gogh painted the sky exactly as it appeared on July 22.

The authors themselves allow for the possibility that the final composition combined observations from different nights and artistic choices made over time.

Other scholars have also questioned aspects of astronomical reconstructions of the painting, including the exact placement of Venus and the chronology implied by Van Gogh's correspondence.

So the scientifically accurate conclusion is not "mystery solved."

It is that a new quantitative reconstruction provides a strong and testable astronomical clue connecting the painting to a specific pre-dawn sky.

Why this matters

The study is interesting because it turns a long-running art-historical question into a measurable geometric problem.

Instead of simply saying that a painted star pattern resembles a constellation, the researchers quantified the similarity and then checked whether the candidate stars, Moon and Venus were actually visible together from the relevant location.

That makes this a rare case where astronomy, geometry, historical documents and art analysis converge on the same question.

Editorial preparation: Arşen Kaan

Primary source

Elijah Jeong-hyun Kim, Suna Kang, Jungwoo Song & Ho Jin, "The actual sky of Van Gogh's Starry Night: a multidisciplinary reconstruction," Scientific Reports 16, 31109 (2026). DOI: 10.1038/s41598-026-73025-5.

In 1985, while working aboard the Soviet space station Salyut 7, cosmonaut Vladimir Dzhanibekov noticed something startling.

A wing nut spinning freely in microgravity maintained its orientation for a while, then abruptly flipped by roughly 180 degrees — and later flipped again.

No motor drove the motion. No impact was required. The behaviour emerged from the dynamics of a freely rotating rigid body.

The phenomenon is now commonly called the Dzhanibekov effect, the tennis-racket theorem, or the intermediate-axis theorem.

Three principal axes

Any rigid body has three mutually perpendicular principal axes associated with three principal moments of inertia, which we can label I₁, I₂ and I₃.

If I₁ < I₂ < I₃, torque-free rotation about the axis associated with the smallest moment and the axis associated with the largest moment is stable.

Rotation about the intermediate axis is unstable.

A tiny perturbation grows, the orientation of the object changes dramatically in the body frame, and the object appears to execute repeated half-turn flips while its total angular momentum remains conserved in inertial space.

Euler's equations

The behaviour follows directly from Euler's equations for torque-free rigid-body rotation:

I₁ dω₁/dt = (I₂ − I₃)ω₂ω₃

I₂ dω₂/dt = (I₃ − I₁)ω₃ω₁

I₃ dω₃/dt = (I₁ − I₂)ω₁ω₂

When the object is spinning almost exactly around the intermediate principal axis, small deviations do not remain small. They grow, producing the characteristic tumbling motion.

Could Earth do the same thing?

Not in the simple sense suggested by viral videos.

Earth is not a freely tumbling rigid wing nut. It is a rotating, self-gravitating, deformable planet with an equatorial bulge, a fluid outer core, oceans and atmosphere, and it rotates very close to its axis of maximum moment of inertia.

That configuration is rotationally stable.

Earth does exhibit small variations in the position of its rotation axis relative to the crust, including the Chandler wobble, a free wobble with a period of roughly 14 months.

But that is not a 180-degree Dzhanibekov flip.

Magnetic pole reversal is something else

The phrase "pole shift" often causes confusion.

Earth's magnetic poles can reverse over geological time because the magnetic field is generated by fluid motion in the outer core.

A magnetic reversal does not mean the entire solid Earth physically turns upside down.

Magnetic-field reversals and rigid-body rotational flips are completely different physical phenomena.

Why spacecraft engineers care

The same rotational mechanics matters for satellites and spacecraft.

Spacecraft attitude systems use devices such as reaction wheels, control-moment gyroscopes and thrusters to manage orientation and angular momentum.

Engineers must understand principal axes, moments of inertia and rotational stability to avoid unwanted tumbling and to control pointing accurately.

The real lesson

The Dzhanibekov effect is one of those cases where ordinary intuition fails but classical mechanics does not.

A rigid body can flip dramatically even while total angular momentum and rotational energy remain conserved.

The instability is real.

The idea that Earth should therefore suddenly turn over is not.

Editorial preparation: Arşen Kaan

Sources

Mardešić, P., Gutierrez Guillen, G. J., Van Damme, L. & Sugny, D. (2020). Geometric Origin of the Tennis Racket Effect. Physical Review Letters 125, 064301. DOI: 10.1103/PhysRevLett.125.064301.

Trivailo, P. M. et al., historical and spacecraft-dynamics discussion of the Dzhanibekov effect and intermediate-axis rotation.

Modern physics is on the verge of a revolution.

What if some of the most fundamental assumptions of modern physics are about to be rewritten?

Today, Arşen Kaan’s English-language catalogue expands with The Greatest Breakthroughs of Modern Physics: The Most Important Developments from 2025–2026 Research.

A guide to a rapidly changing scientific landscape

Groundbreaking scientific studies published in 2025–2026 have revealed developments that could profoundly change the way we understand the universe.

New observations are challenging our current view of dark energy. The James Webb Space Telescope is discovering enormous black holes that appear to have formed far earlier than existing models would normally predict. Gravitational waves are opening an entirely new window onto the cosmos. Meanwhile, quantum computers are reaching milestones that seemed out of reach only a few years ago.

Thirty-five important developments

The book examines 35 of the most important scientific developments in modern physics from 2025–2026. It draws on current research while presenting complex ideas in clear, accessible language without compromising scientific accuracy.

Its themes span cosmology, gravitational waves, quantum technology, particle physics and new states of matter — a new map of reality shaped by current science.

Now available in English

The new English edition is available today. It is written for readers who want to understand not only what researchers have discovered, but why these results matter and which questions remain open.

Arşen Kaan Science Author

Inside the universe, there may be a boundary so small that no microscope could ever see it directly.

Imagine starting from a human eye and diving into the pupil: tissue gives way to molecules, then to a single atom. But atoms are not the end.

From atoms to quarks

In school, electrons are often pictured orbiting an atomic nucleus like planets around the Sun. Quantum mechanics gives us a very different description: an electron is represented by a quantum state whose position is described probabilistically. Around the tiny, dense nucleus, it is better visualised as a diffuse probability cloud than as a miniature planet.

Inside the nucleus are protons and neutrons. Inside them are quarks, bound by the strong interaction and its gluon field. As far as present experiments can determine, quarks and electrons behave as elementary particles with no resolved internal structure.

High-energy collider experiments probe extraordinarily short distances, roughly down to the 10⁻¹⁹–10⁻¹⁸ metre range depending on the process and interpretation. Yet even that is still enormously larger than the Planck scale.

The logarithmic descent

10⁻¹⁵ m — proton scale

10⁻¹⁸ m — collider scale

10⁻²⁵ m

10⁻³⁰ m

10⁻³⁵ m

And there it is:

PLANCK LENGTH ≈ 1.6 × 10⁻³⁵ METRES

This does not prove that the Planck length is the smallest possible distance. It identifies a scale at which our present descriptions of nature are expected to become incomplete.

Where our current map stops working

On one side stands general relativity: curved spacetime, black holes, gravitational waves and Einstein’s field equations.

On the other stands quantum theory: quantum fields, probability amplitudes and the microscopic behaviour of matter.

Near the Planck regime, these frameworks cannot simply be combined using the methods that work at ordinary energies. Straightforward calculations can generate uncontrolled divergences, signalling that a deeper theory of quantum gravity is needed.

Physics itself does not collapse. Our map becomes incomplete.

What could lie underneath?

String theory proposes that point-like particles may be replaced by unimaginably small vibrating strings, with different vibrational states corresponding to different particles. This framework has not been experimentally confirmed.

Loop quantum gravity explores whether geometry itself has a discrete quantum structure described by spin networks. This should not be reduced to the simple claim that space is made of ordinary pixels.

Other research programmes include causal-set theory and asymptotic safety.

There are multiple serious approaches, but no final experimentally established answer.

The deepest remaining question

We descended from atoms to nuclei and from nuclei to quarks. Below the scales we can currently test, one question remains:

What is spacetime itself made of?

Vibrating strings? Quantum geometry? A causal structure? Or something humanity has not yet imagined?

The smallest scales may hide the universe’s greatest mystery.

THE PLANCK SCALE

WHERE OUR CURRENT THEORIES BECOME INCOMPLETE

Arşen Kaan arXiv Series

Sources: CERN Standard Model resources and research literature on quantum gravity, string theory, loop quantum gravity, causal sets and asymptotic safety.

The standard cosmological picture successfully describes an expanding universe, but extrapolating classical general relativity far enough into the past leads to a singularity. Many physicists interpret that singularity not as a known physical object, but as a sign that the classical theory has reached its limit.

A recent preprint by Wagno Cesar e Silva, Nicolas R. Bertini and Ilya L. Shapiro studies a different possibility: the expanding universe may have been preceded by a contracting phase that avoided the singularity through a semiclassical cosmological bounce.

What is the trace anomaly?

Classically, the energy–momentum tensor of radiation has a vanishing trace. Quantum effects can change that result. After renormalisation, the expectation value of the trace need not vanish: ⟨Tᵘᵤ⟩ ≠ 0. This is known as a trace, or conformal, anomaly.

The anomaly is not a random “quantum glitch.” It is a calculable consequence of quantum field theory in curved spacetime. Its contribution depends on the field content and the associated beta functions.

How the bounce appears in this model

In the scenario examined by the authors, an initially contracting universe is not empty. As contraction raises the temperature and density, its matter content behaves increasingly like radiation. The anomaly-induced contribution then modifies the semiclassical gravitational equations.

For a positive overall beta function in the matter sector, the model can generate a nonsingular bounce: contraction slows, reaches a minimum scale and changes into expansion. In that limited, effective sense, the quantum correction opposes continued collapse.

This does not mean that gravity universally becomes repulsive whenever density is high. The result belongs to a specific semiclassical framework and depends on assumptions about quantum fields, the effective action and the cosmological background.

What is new in arXiv:2608.09720?

The paper develops a low-energy form of the nonlocal anomaly-induced effective action. The authors rewrite the action locally by introducing auxiliary scalar fields, avoiding higher derivatives in the resulting formulation. This is intended as groundwork for studying primordial cosmological perturbations in the bounce scenario.

What remains unproven

No observation has established that our universe passed through an earlier contracting phase. The preprint does not provide direct evidence for a pre–Big Bang universe, and it has not turned the bounce into a confirmed replacement for standard early-universe cosmology.

The scientifically careful conclusion is narrower but still important: within this semiclassical model, quantum trace-anomaly effects can produce a mathematically consistent nonsingular bounce under stated conditions. Whether that model describes our universe will depend on its perturbation predictions, theoretical consistency and future observational tests.

Arşen Kaan

Black holes are among the most mysterious objects in the universe. Their defining feature is the event horizon — a boundary beyond which nothing, not even light, can escape.

But one of the deepest questions in modern theoretical physics is not simply what a black hole looks like. It is this: how do quantum fields behave near a horizon?

A recent theoretical study may offer a clearer mathematical way to think about that question.

A Rindler horizon as a theoretical laboratory

The researchers did not study an astrophysical black hole directly. Instead, they used a simplified but extremely important model known as a Rindler horizon.

A Rindler horizon appears when an observer undergoes constant acceleration in flat spacetime. Mathematically, it shares several local properties with a black-hole horizon, which makes it a powerful theoretical laboratory for studying quantum field theory near horizons.

The work focuses on the relationship between modular theory, affine symmetries, quantum algebras and the Unruh effect.

Why the vacuum can look thermal

The quantum vacuum is not as simple as it appears. For an inertial observer, empty space may look like vacuum. But for a uniformly accelerating observer, that same vacuum can appear thermal. This phenomenon is known as the Unruh effect.

The remarkable point is that this thermality is deeply connected to mathematical symmetries. This is where Tomita–Takesaki modular theory becomes important.

Instead of describing quantum physics only in terms of particles, modular theory studies the algebra of observables associated with a region of spacetime. In this framework, vacuum structure, quantum entanglement, thermal behaviour and spacetime symmetries can be connected within a single mathematical language.

Modular flow and affine symmetry

The study examines how modular flow on the Rindler horizon is related to dilations and affine transformations. In simple terms, the researchers show that the thermal behaviour seen by accelerated observers can be understood through a minimal symmetry structure acting on the horizon.

Another important ingredient is the Mellin transform. It provides a natural bridge between Minkowski modes and Rindler modes, helping reveal how different descriptions of the same quantum field are related. This gives a more unified group-theoretic picture of the Unruh effect.

What the result does — and does not — establish

The study does not solve the black-hole information paradox. It does not provide a complete theory of quantum gravity, and it does not describe realistic astrophysical black holes in full detail. The analysis is based on an idealised Rindler horizon and a simplified quantum-field model.

Its broader significance is nevertheless important. Modern approaches to black-hole thermodynamics, Hawking radiation, quantum gravity and holography increasingly rely on the algebraic structure of quantum field theory.

Modular theory may therefore become an increasingly important language for understanding how spacetime, thermality and quantum information are connected.

One profound possibility is that spacetime geometry itself may not be the most fundamental structure. Geometry could instead emerge from deeper relationships between quantum states, operator algebras and modular flow. That idea remains speculative, but it is an active direction in modern theoretical physics.

Perhaps the deepest secrets of black holes will not be revealed only by larger telescopes. Perhaps they will also be uncovered through the mathematics hidden inside quantum theory.

Arşen Kaan

One of modern theoretical physics’ deepest questions is deceptively simple: are space, time, matter and gravity fundamental, or could they emerge from a deeper quantum-informational structure?

Arşen Kaan’s Modular Theory and the New Language of Quantum Reality explores this question through Tomita–Takesaki modular theory, operator algebras, quantum field theory and recent discussions of quantum gravity.

What does “modular” mean?

At the algebraic level, quantum observables can be organised in von Neumann algebras. Given a suitable algebra and state, Tomita–Takesaki theory constructs a modular operator and a canonical flow: σₜ(A) = ΔⁱᵗAΔ⁻ⁱᵗ.

This mathematical flow is not automatically ordinary physical time. Yet in important settings it acquires a geometric meaning. The Bisognano–Wichmann theorem, for example, connects modular flow for a Rindler wedge with Lorentz boosts. Such results motivate the careful question of whether time and geometry may sometimes be recovered from deeper algebraic relations.

Why crossed products matter

Local algebras in relativistic quantum field theory are generally Type III and do not possess the ordinary finite trace familiar from elementary quantum mechanics. By enlarging an algebra to incorporate its modular flow, the crossed product M ⋊σ ℝ can provide a semifinite setting in which trace- and entropy-related questions become more manageable.

Recent work in gravitational physics, including discussions associated with Edward Witten, has brought this construction into renewed focus. The book follows the conceptual route from Tomita–Takesaki theory to these crossed-product methods.

Information, geometry and black holes

Black-hole thermodynamics, holography, entanglement and relative entropy suggest that matter, information and geometry may not be independent layers of reality. Modular theory supplies a precise mathematical vocabulary with which some of these connections can be investigated.

The book does not claim that emergent time or emergent spacetime has been experimentally established. It presents a research frontier: a shared framework in which modular flow, KMS states, Type III factors, relative entropy, holography and quantum gravity can be examined together.

A new international edition

Following the Turkish and German editions, the English edition opens this discussion to a wider readership interested in mathematical physics, quantum foundations, spacetime emergence and quantum information.

The central question is no longer only: how does the quantum world work? A deeper question may be: from what underlying structure do time, geometry, information and physical reality itself emerge?

For more than a century, fundamental physics has repeatedly demoted structures once considered elementary. Quantum field theory treats particles as excitations of fields; general relativity makes spacetime geometry dynamical. Quantum gravity now raises a deeper question: could spacetime itself be emergent?

From objects to relations

Algebraic quantum field theory assigns an algebra of observables 𝒜(O) to a spacetime region O. The algebra specifies which measurements are possible and how they relate. This replaces a picture built only from objects with one in which relations between observables carry primary information.

The Tomita–Takesaki mechanism

For a von Neumann algebra M and a suitable cyclic and separating state Ω, the Tomita operator has the polar decomposition S = JΔ¹ᐟ². The modular operator Δ generates a one-parameter automorphism group, σₜ(A) = ΔⁱᵗAΔ⁻ⁱᵗ.

The parameter is modular time, not automatically ordinary clock time. Yet in special settings the flow becomes geometric. For the vacuum restricted to a Rindler wedge, modular flow is associated with Lorentz boosts and KMS thermality.

Reconstructing geometry

Recent operator-algebraic work studies conditions under which causal, metric and curvature information may be recovered from algebras of quantum matter in semiclassical regimes. This does not prove that the universe is literally “made of algebra.” It changes the reconstruction problem: how much of spacetime can be derived from quantum observables rather than assumed in advance?

Modular geometry and holography

Modular Berry transport, entanglement-wedge reconstruction and quantum error correction provide related clues. In holographic models, the algebra of observables reconstructible from boundary data can correspond to a bulk region. Geometry and information accessibility begin to look like two descriptions of the same organisation.

Black holes as laboratories

Black holes combine quantum theory, gravity, thermodynamics and information. Their local quantum fields naturally involve Type III algebras, while gravitational extensions and crossed products can lead to Type II structures with a semifinite trace. This gives a controlled language for entropy and horizon observables without claiming that one construction has already completed quantum gravity.

What about matter?

Particles are already representation-dependent excitations in quantum field theory. Superselection theory shows how charge sectors can be encoded in representations of observable algebras. That motivates — but does not yet establish — a possible hierarchy: algebra → state → modular dynamics → geometry → fields → matter.

What remains open

A fundamental theory would still need to explain why the low-energy world is 3+1-dimensional, why the Standard Model has its observed gauge group and particle content, and what falsifiable predictions distinguish the framework from existing physics.

The scientifically careful conclusion is therefore neither “matter is an illusion” nor “the universe is software.” The stronger, defensible claim is that operator algebras and quantum states may contain far more geometric and dynamical information than traditional formulations make explicit. Perhaps matter and spacetime are not the beginning of the story, but macroscopic expressions of a deeper relational structure.

Particle physics once faced a “hadron zoo”: a growing catalogue of particles that only became intelligible after the quark model revealed a deeper organising principle. Today, the many short-lived X, Y and Z states are creating a new classification problem.

Using a high-energy photon beam on a liquid-hydrogen target, the GlueX experiment at Jefferson Lab studied the strangeonium region. The team was looking for the previously reported Y(2175), but did not see a clear confirmation of that state in the analysed channel.

Instead, the researchers reported two structures. One, labelled Y(2240), appears near 2.24 GeV with a local statistical significance of about five sigma. A second, X(1830), appears near 1.82 GeV with evidence at roughly three sigma.

Those signals do not yet tell physicists what the structures are. Possible explanations include conventional resonances, multiquark configurations, hadronic molecules, gluonic hybrid states or effects produced by interfering amplitudes. Determining the correct interpretation requires additional channels, detailed amplitude analyses and independent confirmation.

The result matters because quantum chromodynamics explains the strong interaction but remains difficult to solve in the energy regime where quarks and gluons bind into hadrons. New spectroscopy data can expose how that binding works.

The scientifically careful conclusion is therefore not that two exotic particles have been definitively discovered. GlueX has reported two significant structures whose precise nature remains open.

The experiment did not create real gravity, spacetime or a traversable wormhole. Researchers implemented the HaPPY code—a simplified holographic quantum error-correcting model—on a trapped-ion quantum computer.

In their 2026 preprint, the team reported an experimental test of the Faulkner–Lewkowycz–Maldacena relation inside this model. They then introduced non-stabilizer resources, often called magic, and measured entropic precursors expected in models of emergent gravity.

The researchers also built a code construction whose entropic behavior resembles that of a highly quantum wormhole. “Resembles” is essential: no tunnel through physical spacetime was opened and no object was transported. This was an analogue simulation of mathematical relationships in a controlled quantum system.

The result matters because parts of the quantum-information language used in holographic gravity can now be examined experimentally rather than only through equations. Quantum processors may therefore become useful testbeds for simplified models of emergent geometry.

But the HaPPY code is not a complete model of our universe, and the experiment does not prove that spacetime is made of quantum information. The careful conclusion is that a quantum computer reproduced selected gravity-like signatures predicted within a particular holographic toy model.

Clocks measure durations, and relativity explains why different paths through spacetime can accumulate different amounts of proper time. Physics does not require one universal clock shared by every observer.

The question of whether time is fundamental arises in quantum gravity. Certain formulations describe a global state without an external time parameter, while changes can be described through correlations between subsystems. Turning that idea into a complete account of physical clocks remains a substantial problem.

The thermal time hypothesis offers another perspective. Given an appropriate algebra of observables and a state, modular theory supplies a mathematical flow. Identifying that flow with physical time is an additional proposal, not a consequence that applies automatically to every system.

Likewise, results relating spatial geometry to quantum entanglement do not by themselves explain the emergence of time or our experience of its passage. Temperature can offer an analogy for emergence, but an analogy is not a derivation.

These ideas are active theoretical explorations. They do not show that time is fake, nor that a specific model of emergent time has been experimentally established. The productive question is how known clock behaviour and relativistic dynamics might arise within a deeper description.

Atoms, particles and quantum fields are successful parts of our physical description. Asking whether a deeper description exists does not make their observed behaviour disappear.

In holographic approaches to quantum gravity, a gravitational spacetime can be related to a quantum theory with a different description of its degrees of freedom. The pattern of entanglement can be closely related to geometric connections in that spacetime.

Mark Van Raamsdonk explored how reducing entanglement between parts of a holographic quantum system can correspond to separating regions of the associated geometry. This is a concrete theoretical setting in which relationships between degrees of freedom help describe space.

It does not prove that our universe is a computer simulation. Nor does it demonstrate that matter, a brain or a memory consists of an independent substance called information. Information is defined through physical states, observables and their correlations; its interpretation must be specified.

The broader possibility that familiar spacetime emerges from a deeper quantum structure remains important. Yet a result in a particular holographic model is not a completed description of our cosmological universe.

The strongest conclusion is also the most interesting: quantum information gives physicists new tools for investigating geometry and gravity. Whether it ultimately supplies a fundamental account of all reality is still open.

Sixty-six million years ago, a roughly 10-kilometre-wide asteroid struck near today’s Yucatán Peninsula. The impact formed the Chicxulub crater and released enough energy to transform conditions across the planet.

Rock, dust, soot and sulfur-rich aerosols were driven into the atmosphere. Sunlight diminished, temperatures fell and photosynthesis was disrupted. The resulting collapse of food webs contributed to the end-Cretaceous mass extinction, in which about three-quarters of species disappeared.

The impact is strongly supported as the principal trigger of that extinction, although the environmental crisis unfolded through several interacting processes. Non-avian dinosaurs were among its most famous victims, while birds, mammals and many other groups survived in reduced and unevenly distributed populations.

The disappearance of dominant dinosaur lineages created ecological opportunities that surviving mammals later exploited. Mammals diversified dramatically during the Cenozoic, and one much later branch eventually produced primates, hominins and Homo sapiens.

It is therefore reasonable to say that the impact changed the evolutionary conditions from which humans eventually emerged. But the counterfactual remains uncertain: science cannot prove exactly what would have evolved had the asteroid missed Earth, and human evolution was not a predetermined outcome.

The event is a powerful reminder that biological history can turn on planetary-scale accidents. For one set of organisms, Chicxulub marked catastrophe. For others, it opened a world of new possibilities.

For decades, humanity has asked whether we are alone. The exoplanet K2-18b, about 124 light-years away, has become one of the most closely watched places in that search.

K2-18b orbits within its star’s habitable zone, but that does not automatically make it habitable. It is a sub-Neptune more than twice Earth’s radius, and scientists still debate whether it has an ocean beneath a hydrogen-rich atmosphere or a much deeper gaseous envelope.

In 2025, a team led by Nikku Madhusudhan analysed a JWST MIRI transmission spectrum and reported tentative, roughly three-sigma evidence consistent with dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS).

On Earth, DMS is produced mainly by biological activity, especially marine microorganisms. That makes it interesting as a possible biosignature — but not a unique or automatic sign of life. Abiotic sources, incomplete molecular data and model choices must also be considered.

The result remains controversial. Independent teams analysing JWST data have found that the MIRI spectrum can be fitted without a robust DMS or DMDS detection. A comprehensive reanalysis of the near-infrared observations confirmed methane but found no reliable evidence for DMS or carbon dioxide, and showed that an oxygen-poor mini-Neptune remains a viable interpretation.

This is how frontier science works: one analysis identifies a possible signal, other teams test whether it survives different reductions, molecular lists and atmospheric models, and new observations decide between them.

The accurate conclusion is therefore cautious. JWST has not detected life on K2-18b. It has produced atmospheric spectra that prompted a serious but unresolved biosignature debate. More precise observations and independent confirmation are required before any biological interpretation can be supported.

Even without a confirmed biosignature, the achievement is remarkable: astronomers can now probe the chemistry of a distant planet’s atmosphere and test the possibility of life with real data rather than speculation alone.

Stars forged much of the carbon, oxygen and other heavy elements that later became planets and living organisms. But some of the earliest luminous objects may have been powered by a radically different mechanism.

Dark-star theory proposes that primordial objects made mostly of hydrogen and helium could have been heated by the annihilation of dark-matter particles rather than initially relying on ordinary nuclear fusion. The released energy could delay collapse and allow the objects to grow to enormous masses.

Some models predict supermassive dark stars reaching hundreds of thousands or even millions of solar masses. Their eventual collapse could provide heavy seeds for the supermassive black holes that astronomers observe surprisingly early in cosmic history.

JWST has now supplied spectra for extremely distant JADES objects. In a 2025 PNAS study, researchers found that two previously proposed candidates, JADES-GS-z11-0 and JADES-GS-z13-0, remained consistent with dark-star models. They also identified JADES-GS-z14-0 and JADES-GS-z14-1 as additional spectroscopic candidates.

One object, JADES-GS-z14-0, showed a tentative absorption feature that could match a predicted helium signature. However, ALMA also detected likely oxygen emission associated with the source, making the simple picture of an isolated dark star less plausible.

These objects are therefore candidates, not discoveries of dark stars. Young galaxies, supermassive primordial stars and other astrophysical systems can produce overlapping observational signatures. Better spectra and diagnostic features are needed to distinguish among them.

If even one candidate were confirmed, the consequences would be profound. It would reveal a new phase of stellar evolution, provide information about dark matter and offer a possible route to the rapid appearance of massive black holes.

For now, the most accurate statement is also the most exciting: JWST has found distant objects compatible with a remarkable hypothesis, and astronomy finally has observations capable of testing it.

When humans return to the Moon, we will not go alone. Spacecraft, tools, habitats and spacesuits will inevitably carry microorganisms associated with Earth and the human body.

For a long time, the lunar surface seemed like a natural steriliser: it has no substantial atmosphere, experiences extreme temperatures and is exposed to intense ultraviolet and cosmic radiation. A NASA-led study published in 2026, however, suggests that conditions near the lunar south pole may be more complicated.

Using lunar temperature and radiation data together with laboratory knowledge of five bacteria and fungi, researchers mapped small sheltered niches where some organisms might remain viable. Permanently shadowed terrain, cold seasons and even very small patches of shade may protect dormant microbes from the harshest exposure.

The study concerns survival, not active growth or a self-sustaining lunar ecosystem. Some tested microorganisms may persist for at least a lunar day in favourable niches, while the hardy fungus Aspergillus niger could potentially survive longer under limited exposure.

This matters because the Moon’s south polar region is a major destination for future missions. Permanently shadowed craters may contain ancient water ice and preserve chemical records of the Moon’s history. Earth organisms deposited by astronauts or equipment could alter samples or make later measurements harder to interpret.

The same planetary-protection problem extends beyond the Moon. Future missions searching for signs of life on Mars must be able to distinguish an indigenous biological signal from contamination transported from Earth.

Contamination cannot be reduced to zero. Human skin, equipment and habitats continuously shed biological material. The practical goal is therefore to document, minimise and monitor what we bring.

There is also a scientific opportunity: carefully controlled experiments on the Moon could reveal how long terrestrial microbes remain viable in extraterrestrial environments that are difficult to reproduce perfectly on Earth.

The question is no longer only whether life exists beyond Earth. It is also whether we can explore another world without confusing its history with traces of our own.

Scientific note: The study identifies potential survival niches based on modelling and experimental tolerance data. It does not show that introduced microbes are currently growing on the Moon.

Spiders, scorpions and many snakes use venom, but crustaceans were long thought to be an exception. That assumption changed with the study of a blind, cave-dwelling remipede from the Yucatán Peninsula: Xibalbanus tulumensis.

This unusual animal lives in anchialine cave systems — flooded underground environments where fresh and marine waters meet. It has no functional eyes and hunts other small crustaceans in darkness.

Researchers showed that Xibalbanus possesses a specialised venom-delivery system connected to its front limbs. The secretion contains enzymes and peptide toxins that can help immobilise prey and begin breaking down tissues before feeding.

The finding made remipedes the first, and so far only, crustaceans with a formally described venom system. It overturned the older idea that venom was absent from a group containing tens of thousands of known species.

Scientists later characterised a family of peptides called xibalbins. Several have an inhibitor cystine-knot structure, a compact molecular arrangement known for resisting heat, enzymes and harsh chemical conditions.

Tests showed that all examined xibalbin variants inhibited potassium channels in mammalian systems. Xib1 and Xib13 also affected voltage-gated sodium channels and signalling in sensory neurons.

Ion channels control electrical activity in nerves, muscles and other cells, so highly selective molecules that modify them can become useful research tools or starting points for drug development. This does not mean that xibalbins are already treatments; their selectivity, safety, dosage and effects in living organisms require much more study.

A predator hidden in underwater caves has therefore revealed both an unexpected chapter in venom evolution and a collection of molecules with potential pharmacological value.

Scientific note: Xibalbanus tulumensis was described decades ago, and its venom system was reported before the recent xibalbin work. The newer research concerns the detailed molecular and pharmacological properties of its toxins, not the first discovery of the animal itself.

For decades, physicists have treated space and time as the fundamental stage on which reality unfolds. But what if spacetime itself is not fundamental? What if the universe emerges from something deeper?

This possibility lies at the heart of several influential research programmes in modern theoretical physics, many connected to the work of Edward Witten, one of the most influential mathematical physicists of our time.

Beyond Space and Time

Traditional physics treats spacetime as the background structure of reality. Work in string theory, quantum gravity and holography suggests a different picture. In several modern frameworks, geometry may emerge from quantum information, entanglement and deeper algebraic structures.

The universe may not ultimately be built from particles moving through a pre-existing space. Instead, space itself may arise from relationships between quantum systems.

The Holographic Revolution

One of the most remarkable developments in theoretical physics is the holographic principle. According to this idea, the physics inside a volume of space may be encoded by a theory defined on a lower-dimensional boundary.

In simple terms, a higher-dimensional gravitational world can, in certain theoretical settings, have an equivalent lower-dimensional description. This does not establish that our everyday three-dimensional cosmos is literally a projection on a physical outer wall. It is a mathematically precise duality in specific models and an important clue about quantum gravity.

Witten’s Lasting Influence

Edward Witten did not merely contribute to string theory. His work connected geometry, topology, quantum field theory and gravity in ways that continue to shape modern research.

Researchers now ask whether spacetime emerges from quantum entanglement, whether gravity can be understood through information, and whether parts of the universe can be reconstructed from algebraic relations rather than fundamental geometric objects.

A New Picture of the Universe

The next revolution in fundamental physics may reveal that spacetime is not the foundation of reality but a consequence of something deeper. If that happens, future historians may look back at ideas developed by Witten and his contemporaries as part of the beginning of a new scientific worldview.

The greatest mystery of the cosmos may not be what exists inside space and time. It may be why space and time exist at all.

Scientific status: Emergent spacetime and holographic duality are active areas of theoretical research. They provide powerful results in specific mathematical frameworks but are not a confirmed description of our universe as a whole.

Sources • Maldacena, J. (1998). The Large N Limit of Superconformal Field Theories and Supergravity. • Van Raamsdonk, M. (2010). Building Up Spacetime with Quantum Entanglement. • Witten, E. (1995). String Theory Dynamics in Various Dimensions. • Witten, E. (2022). Why Does Quantum Field Theory in Curved Spacetime Make Sense?

What if the cosmos is not fundamentally built from matter? What if reality is built from information?

One of the most fascinating ideas in modern theoretical physics suggests that aspects of spacetime may emerge from mathematical principles resembling those used to protect data inside quantum computers.

Researchers studying holography and quantum gravity discovered a surprising connection between the geometry of spacetime and quantum error-correcting codes. These codes are designed to protect information from noise and corruption, yet related mathematical structures reproduce key properties of certain gravitational systems.

The implication is striking: the fabric of spacetime may behave, in some theoretical models, like an information-encoding system.

In this picture, space is not fundamental. Distance is not fundamental. Geometry emerges from deeper quantum relationships. Information located in a gravitational “bulk” can be redundantly encoded on a lower-dimensional boundary, allowing it to remain reconstructible even when part of that boundary description is unavailable.

This perspective has become an important clue in the search for a theory that unifies gravity and quantum mechanics. It also helps researchers investigate how information might be preserved in systems involving black holes.

If the connection reflects a deeper law of nature, the universe may be less like a classical machine and more like a robust quantum information structure.

The ultimate laws of nature might not be written only in matter. They may also be written in information.

Scientific status: Holographic quantum error correction is a well-developed theoretical framework and a useful model of bulk–boundary reconstruction. The statement that the entire real universe is literally a quantum computer or a quantum code has not been experimentally established.

Sources • Almheiri, Dong & Harlow (2015). Bulk Locality and Quantum Error Correction in AdS/CFT. • Pastawski et al. (2015). Holographic Quantum Error-Correcting Codes: Toy Models for the Bulk/Boundary Correspondence. • Maldacena, J. (1998). The Large N Limit of Superconformal Field Theories and Supergravity.