Fortnight ending Saturday 18 July 2026. Read time: about 8 minutes.

The school year may be running on fumes, but physics has remained inconveniently busy. A supernova has revealed the birth of a magnetar, a dark-energy model has survived some serious statistical interrogation without settling the Hubble tension, and an orbital engineering story has required the useful distinction between a thruster and a torquer. Elsewhere, Voyager’s one-way signal time is now roughly a day, OCR is still defending a disputed paper, and the Schrödinger equation gets a rare explanation that begins somewhere intelligible.

An inventive cosmological model has met better statistics and emerged only partly victorious.

Researchers have tested a model in which dark energy switches from negative to positive during the universe’s history. The model, known as ΛsCDM, shifts the predicted expansion rate towards the value obtained from nearby supernovae and Cepheid variables.

The latest analysis used data from Planck, the Atacama Cosmology Telescope, the South Pole Telescope, DESI DR2 and the Pantheon+ supernova sample with the SH0ES calibration. Once the researchers replaced simple Gaussian comparisons with more exact statistical tests, the early-universe and galaxy-clustering datasets agreed well. The local measurement of the Hubble constant still sat awkwardly outside the model’s preferred range.

For A-level cosmology, this is an excellent example of a physical model passing several tests while failing the one it was largely invited in to solve. Physics can be rather ungrateful in that way.

Source: Phys.org

Four bumps in a light curve have exposed the engine inside an extraordinarily bright stellar explosion.

Astronomers have reported the first direct evidence of a newborn magnetar powering a superluminous supernova. SN 2024afav, around a billion light-years away, faded in an unusual sequence of four brightness fluctuations. The intervals shortened with time, producing what the researchers describe as a chirp.

Their model places a tilted accretion disc around a rapidly spinning magnetar. Frame dragging causes the disc to precess, periodically changing the light reaching Earth. As the disc moves inward, the precession speeds up and the gaps between the peaks shrink.

The inferred neutron star rotates once every 4.2 milliseconds and has a magnetic field roughly 300 trillion times stronger than Earth’s. It is also a splendid reminder that a light curve is a physical record, not merely a graph astronomers produce after locating the “smooth line” tool.

Source: ScienceDaily

The distinction between turning a spacecraft and propelling it proved important enough for a published correction.

Zenno Astronautics has tested a shoebox-sized superconducting magnetic control system aboard the Mira satellite. Its coils are cooled to about −200 degrees Celsius, allowing them to carry large currents and generate a strong, controllable magnetic field.

That field interacts with Earth’s magnetic field to produce a torque, changing the satellite’s orientation without consuming propellant. Space.com originally described the device as a thruster, then amended the article to call it a torquer. The correction is worth preserving: controlling attitude is not the same as producing linear thrust.

For magnetism lessons, the device offers a modern version of the motor effect with unusually expensive apparatus and a rather less forgiving risk assessment.

Source: Space.com

A 1977 spacecraft now provides a very clean calculation involving wave speed, distance and patience.

A radio signal sent to Voyager 1 takes more than 22 hours to arrive. A response requires another 22 hours or more, assuming the spacecraft receives the command, carries it out and remains in a conversational mood.

For GCSE waves or introductory A-level work, give students the one-way travel time and ask them to calculate Voyager’s distance.

Useful follow-ups include converting this into kilometres and astronomical units, calculating the round-trip delay, and comparing the distance with one light-year. Voyager is also operating with only a few hundred watts from its radioisotope power source, with the available output falling each year.

Source: Space Daily

Updated stellar models turn the planet’s fate into a competition between tidal drag and mass loss.

New calculations suggest that Earth could survive the Sun’s red-giant phases. Tidal interactions with the swollen Sun remove orbital energy and pull planets inward. At the same time, the Sun loses a large fraction of its mass, weakening its gravitational field and allowing surviving planets to migrate outwards.

The revised models predict that Mercury and Venus will be engulfed, while Earth and Mars may settle into wider orbits around the eventual white dwarf. The remaining uncertainty lies mainly in how rapidly the ageing Sun will lose mass.

This works well with A-level gravitational fields or GCSE space physics. Students can identify the competing effects, then explain why reducing the central mass increases the orbital radius. Earth would already have become uninhabitable long before this stage, so the result offers survival in the strict geological sense rather than anything likely to trouble an estate agent.

Source: Space.com

Measurement and feedback can produce trajectories that resemble time-reversed quantum behaviour.

Researchers at Los Alamos have developed control protocols that alter the apparent direction of time in a quantum system. Measurements disturb quantum states and usually establish a preferred temporal direction. The new work combines continuous measurement with a carefully designed control Hamiltonian, allowing the disturbance to be cancelled, amplified or overcorrected.

The resulting stochastic trajectories can resemble processes running backwards. The team also describes a measurement engine capable of extracting useful energy from the monitoring process.

No coffee cup has returned to the staffroom before it was dropped. The work concerns controlled microscopic trajectories, with the energetic and informational costs included. For strong A-level students, it provides a route into time-reversal symmetry, entropy and Maxwell’s demon without pretending that the second law has taken the afternoon off.

Source: ScienceDaily

The board accepts that an older mark scheme was wrong but maintains that the 2025 paper was marked correctly.

OCR has defended its decision not to re-mark a 2025 GCSE maths paper, despite Ofqual upholding a complaint about inconsistencies in the board’s previous materials.

The dispute centres on a question for which a 2021 mark scheme contained incorrect mathematics. OCR says the later paper used the mathematically correct answer and that awarding marks for responses based on the older error would compromise the integrity of the examination. Critics argue that teachers and pupils may have relied on materials supplied by the board itself.

Ofqual told Tes that the matter remained ongoing. It is a maths case, though the wider point travels readily across departments: official past materials are teaching tools, not revealed scripture.

Source: Tes

Paper-level boundaries, examiner reports and marked scripts should make the August post-mortem rather more useful.

For teachers using Pearson Edexcel, the board’s July science update gathers its main results-day tools in one place ahead of A-level results on 13 August and GCSE results on 20 August.

Pearson will publish the official subject grade boundaries on results day, alongside notional boundaries for individual papers. The latter do not create separate grades for each component, but they can help departments judge performance across papers and set more defensible boundaries for future mocks.

ResultsPlus will provide question-level comparisons with national performance, while examiner reports will be available through the same system. Teachers can also download candidates’ marked scripts free of charge through Access to Scripts until 11 December 2026, provided candidate consent has been obtained. Checking that the relevant staff have ResultsPlus and Exam Viewer access before August may save the traditional results-day search for someone who remembers the Edexcel Online password.

The update also points A-level teachers towards Pearson’s physics exemplars from the 2025 series, which pair student responses with examiner commentary on how the mark scheme was applied.

Source: Pearson Edexcel

Laser pulses in an optical fibre have reproduced the backreaction associated with Hawking radiation.

Physicists have built a laboratory analogue of a black-hole event horizon using ultrafast laser pulses travelling through a patterned optical fibre. One pulse changes the fibre’s optical properties, creating a horizon for a second pulse.

Earlier versions of the experiment produced analogue Hawking radiation. The new work detected the recoil of the pulse that formed the horizon: the analogue backreaction expected when radiation carries energy away from a black hole.

The experiment contains no collapsed star and poses little immediate threat to the laboratory. Its value lies in reproducing the same mathematical relationships in a controllable optical system, including the energy transfer that would drive evaporation.

Source: ScienceAlert

Stephen Wolfram’s computational physics programme receives a clear, suitably sceptical examination.

In an interview with New Scientist, Stephen Wolfram (Mathematica and Wolfram Alpha) discusses his proposal that time emerges from the computational evolution of the universe. In this picture, simple rules generate an enormous network of updates, while observers experience a coherent passage of time because they process only a limited part of that structure.

It is highly speculative and far from a settled account of fundamental physics. For teachers or advanced students interested in cellular automata, determinism, emergence and the meaning of physical law, it is still an enjoyable intellectual workout. The paywall may provide an additional exercise in boundary conditions.

Source: New Scientist/ YouTube

Court poetry has supplied another historical observation of a rare stellar explosion.

Astronomers and historians have connected a medieval Arabic poem with the guest star recorded by Chinese and Japanese observers in 1181. The poet Ibn Sanā’ al-Mulk described a new star near Cassiopeia while praising Saladin. The likely date of the poem falls within the period when the object was visible. The record supports the association between the historical supernova and the unusual nebula surrounding IRAS 00500+6713.

It is a compact example of evidence surviving in an unexpected form. Observational astronomy sometimes depends upon spectroscopy, radio telescopes and, apparently, someone being sufficiently flattering about a twelfth-century sultan.

Source: BBC Sky at Night Magazine

Dune: Prophecy has found a second audience while viewers wait for its next series.

Collider reports that Dune: Prophecy has returned to HBO Max’s streaming charts, more than a year after its original release. The prequel follows the origins of the Bene Gesserit several millennia before Paul Atreides begins making avoidable decisions in the desert.

There is no urgent pedagogical purpose here. It is included for departments whose commitment to space physics extends to sandworms, prescience and arguments over whether shields would conserve momentum.

Source: Collider

FloatHeadPhysics builds the equation from matter waves, energy and momentum instead of presenting it as an unexplained commandment.

I finally understood why the universe needs imaginary numbers is a 44-minute attempt to make the origin of the Schrödinger equation intuitive. It begins with the de Broglie and Planck relations, moves through complex plane waves, and shows how differentiation naturally produces the energy and momentum operators.

The video is careful about the role of i, the conservation of probability and the difference between motivating the equation and proving it from classical physics. It is one of the clearest bridges available between A-level wave ideas and undergraduate quantum mechanics.

Anyone who has previously reached the Schrödinger equation, admired it from a safe distance and moved on should try this first.

Source: FloatHeadPhysics

Misconception: Fundamental particles are governed by equations that forbid processes from running backwards.

Better framing: Many microscopic laws are approximately time-reversal symmetric. The familiar arrow of time appears through statistical behaviour, entropy, measurement and interaction with the environment.

Why students get stuck: Everyday processes are overwhelmingly irreversible, so it feels natural to place the irreversibility inside every individual equation. A smashed beaker never reassembles itself, although its constituent particles are not each carrying a small instruction labelled “forwards only”.

Source: ScienceDaily

Trust me, the Float Head Physics video version above is much, much better!

“Remember that all models are wrong; the practical question is how wrong do they have to be to not be useful.”

— George E. P. Box

Source: MacTutor History of Mathematics

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