Direct-to-smartphone satellite operator Lynk Global has officially hung up on Slam Corp, ending a troubled merger with former MLB star Alex Rodriguez’s blank-check firm through a clean break and legal truce.
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The new agreement grants the agency access to data from Hydrosat’s first two satellite missions.
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A large, low density region of space surrounding the Milky Way may explain one of the most puzzling discrepancies in modern cosmology. Known as the Hubble tension, the issue arises from conflicting measurements of how fast the universe is expanding. Now, a new study suggests that the presence of a local cosmic void could explain this mismatch, and significantly improves agreement with observations compared to the Standard Model of cosmology.
“Numerically, the local measurements of the expansion rate are 8% higher than expected from the early universe, which amounts to over six times the measurement uncertainty,” says Indranil Banik, a cosmologist at the University of Portsmouth and a collaborator on the study. “It is by far the most serious issue facing cosmology.”
The Hubble constant describes how fast the universe is expanding and it can be estimated in two main ways. One method involves looking far into the past by observing the cosmic microwave background (CMB). This is radiation that was created shortly after the Big Bang and permeates the universe to this day. The other method relies on the observation of relatively nearby objects, such as supernovae and galaxies, to measure how fast space is expanding in our own cosmic neighbourhood.
If the Standard Model of cosmology is correct, these two approaches should yield the same result. But, they do not. Instead, local measurements suggest the universe is expanding faster than the expansion given by early-universe data. Furthermore, this disagreement is too large to dismiss as experimental error.
One possible explanation is that something about our local environment is skewing the results. “The idea is that we are in a region of the universe that is about 20% less dense than average out to a distance of about one billion light years,” Banik explains. “There is actually a lot of evidence for a local void from number counts of various kinds of sources across nearly the whole electromagnetic spectrum, from radio to X-rays.”
Such a void would subtly affect how we interpret the redshifts of galaxies. This is the stretching of the wavelength of galactic light that reveals how quickly a galaxy is receding from us. In an underdense (of relatively low density) region, galaxies are effectively pulled outward by the gravity of surrounding denser areas. This motion adds to the redshift caused by the universe’s overall expansion, making the local expansion rate appear faster than it actually is.
“The origin of such a [void] would trace back to a modest underdensity in the early universe, believed to have arisen from quantum fluctuations in density when the universe was extremely young and dense,” says Banik. However, he adds, “A void as large and deep as observed is not consistent with the standard cosmological model. You would need structure to grow faster than it predicts on scales larger than about one hundred million light–years”.
To evaluate whether the void model holds up against data, Banik and his collaborator Vasileios Kalaitzidis at the UK’s University of St Andrews compared it with one of cosmology’s most precise measurement tools: baryon acoustic oscillations (BAOs). These are subtle ripples in the distribution of galaxies that were created by sound waves in the early universe and then frozen into the large-scale structure of space as it cooled.
Because these ripples provide a characteristic distance scale, they can be used as a “standard ruler” to track how the universe has expanded over time. By comparing the apparent size of this ruler at observed a different distances, cosmologists can map the universe’s expansion history. Crucially, if our galaxy lies inside a void, that would alter how the ruler appears locally, in a way that can be tested.
The researchers compared the predictions of their model with twenty years of BAO observations, and the results are striking. “BAO observations over the last twenty years show the void model is about one hundred million times more likely than the Standard Model of cosmology without any local void,” says Banik. “Importantly, the parameters of all these models were fixed without considering BAO data, so we were really just testing the predictions of each model.”
While the void model appears promising, Banik says that more data are needed. “Additional BAO observations at relatively short distances would help a lot because that is where a local void would have the greatest impact.” Other promising avenues include measuring galaxy velocities and refining galaxy number counts. “I would suggest that it can be essentially confirmed in the next five to ten years, since we are talking about the nearby universe after all.”
Banik is also analysing supernovae data to explore whether the Hubble tension disappears at greater distances. “We are testing if the Hubble tension vanishes in the high-redshift or more distant universe, since a local void would not have much effect that far out,” he says.
Despite the challenges, Banik remains optimistic. With improved surveys and more refined models, cosmologists may be closing in on a solution to the Hubble tension.
The research is described in Monthly Notices of the Royal Astronomical Society.
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The Cockroft Walton lecture series is a bilateral exchange between the Institute of Physics (IOP) and the Indian Physics Association (IPA). Running since 1998, it aims to promote dialogue on global challenges through physics.
Lee Packer, who has over 25 years of experience in nuclear science and technology and is an IOP Fellow, delivered the 2025 Cockroft Walton Lecture Series in April. Packer gave a series of lectures at the Homi Bhabha Research Centre (BARC) in Mumbai, the Institute for Plasma Research (IPR) in Ahmedabad and the Inter-University Accelerator Centre (IUAC) in Delhi.
Packer is a Fellow of UK Atomic Energy Authority (UKAEA), in which he works on nuclear aspects of fusion technology. He also works as consultant to the International Atomic Energy Agency (IAEA) in Vienna, where he is based in the physics section of the department of nuclear sciences and applications.
Packer also holds an honorary professorship at the University of Birmingham, where he lectures on nuclear fusion as part of their long-running MSc course in the physics and technology of nuclear reactors.
Below, Packer talks to Physics World about the trip, his career in fusion and what advice he has for early-career researchers.
When did you first become interested in physics?
I was fortunate to have some inspiring teachers at school who made physics feel both exciting and full of possibility. It really brought home how important teachers are in shaping future careers and they deserve far more recognition than they often receive. I went on to study physics at Salford University and during that time spent a year on industrial placement at the ISIS Neutron and Muon Source based at the Rutherford Appleton Laboratory (RAL). That year deepened my interest in applied nuclear science and highlighted the immense value of neutrons across real-world applications – from materials research and medicine to nuclear energy.
Can you tell me about your career to date?
I’ve specialised in applied nuclear science throughout my career, with a particular focus on neutronics – the analysis of neutron transport — and radiation detection applied to nuclear technologies. Over the past 25 years, I’ve worked across the nuclear sector – in spallation, fission and fusion – beginning in analytical and research roles before progressing to lead technical teams supporting a broad range of nuclear programmes.
When did you start working in fusion?
While I began my career in spallation and fission, the expertise I developed in neutronics made it a natural transition into fusion in 2008. It’s important to recognise that deuterium-tritium fuelled fusion power is a neutron-rich energy source – in fact, 80% of the energy released comes from neutrons. That means every aspect of fusion technology must be developed with the nuclear environment firmly in mind.
Why do you like about working in fusion energy?
Fusion is an inherently interdisciplinary challenge and there are many interesting and difficult problems to solve, which can make it both stimulating and rewarding. There’s also a strong and somewhat refreshing international spirit in fusion — the hard challenges mean collaboration is essential. I also like working with early-career scientists and engineers to share knowledge and experience. Mentoring and teaching is rewarding, and it’s crucial that we continue building the pipelines of talent needed for fusion to succeed.
Tell me about your trip to India to deliver the Cockroft Walton lecture series?
I was honoured to be selected to deliver the Cockroft-Walton lecture series. Titled “Perspectives and challenges within the development of nuclear fusion energy”, the lectures explored the current global landscape of fusion R&D, technical challenges in areas such as neutronics and tritium breeding, and the importance of international collaboration. I shared some insights from activities within the UK and gave a global perspective. The reception was very positive – there’s strong enthusiasm within the Indian fusion community and they are making excellent contributions to global progress in fusion. The hosts were extremely welcoming, and I’d like to thank them for their hospitality and the fascinating technical tours at each of the institutes. It was an experience I won’t forget.
What are India’s strengths in fusion?
India has several strengths including a well-established technical community, major national laboratories such as IPR, IUAC and BARC, and significant experience in fusion through its domestic programme and direct involvement in ITER as one of the seven member states. There is strong expertise in areas such as nuclear physics, neutronics, materials, diagnostics, and plasma physics.
What could India improve?
Where India might improve could be in building further on its amazing potential – particularly its broader industrial capacity and developing its roadmap towards power plants. Common to all countries pursuing fusion, sustained investment in training and developing talented people will be key to long-term success.
When do you think we will see the first fusion reactor supplying energy to the grid?
I can’t give a definitive answer for when fusion will supply electricity to the grid as it depends on resolving some tough, complex technical challenges alongside sustained political commitment and long-term investment. There’s a broad range of views and industrial strategies being developed within the field. For example, the UK Government’s recently published clean energy industrial strategy mentions the Spherical Tokamak for Energy Production programme, which aims to deliver a prototype fusion power plant by 2040 at West Burton, Nottinghamshire, at the site of a former coal power station. The Fusion Industry Association’s survey of private fusion companies reports that many are aiming for fusion-generated electricity by the late 2030s, though time projections vary.
There are others who say it may never happen?
Yes. On the other hand, some point to several critical hurdles to address and offer more cautious perspectives and call for greater realism. One such problem, close to my own interest in neutronics, is the need to demonstrate tritium-breeding blanket-technology systems and to develop lithium-6 supplies at the required scale for the industry.
What are the benefits of doing so?
The potential benefits for society are too significant to disregard on the grounds of difficulty alone. There’s no fundamental physical reason why fusion energy won’t work and the journey itself brings substantial value. The technologies developed along the way have potential for broader applications, and a highly skilled and adaptable workforce is developed with this.
What advice do you have for early-career physicists thinking about working in the field?
Fusion needs strong collaboration between people from across the board – physicists, engineers, materials scientists, modellers, and more. It’s an incredibly exciting time to get involved. My advice would be to keep an open mind and seek out opportunities to work across these disciplines. Look for placements, internships, graduate or early career positions and mentorship – and don’t be afraid to ask questions. There’s a brilliant international community in fusion, and a willingness to support those with kick-starting their careers in this field. Join the effort to develop this technology and you’ll be part of something that’s not only intellectually stimulating and technically challenging but is also important for the future of the planet.
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The two-day exercise held in Colorado Springs marked the second in a series of Commercial Augmentation Space Reserve (CASR) wargames
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As my arms lift from my sides, and the rest of my body follows suit toward the ceiling of a modified Boeing 727—next to scientists, astronauts, engineers and activists—I think, “How did I get here?” I’ve been enamored with space since I saw the Northern Lights in my backyard in fifth grade (a rare occurrence […]
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The UK should focus on being a “responsible, intelligent and independent leader” in space sustainability and can make a “major contribution” to the area. That’s the verdict of a new report from the Institute of Physics (IOP), which warns, however, that such a move is possible only with significant investment and government backing.
The report, published together with the Frazer-Nash Consultancy, examines the physics that underpins the space science and technology sector. It also looks at several companies that work on services such as position, navigation and timing (PNT), Earth observation as well as satellite communications.
In 2021/22 PNT services contributed over 12%, or about £280bn, to the UK’s gross domestic product – and without them many critical national infrastructures such as the financial and emergency systems would collapse. The report says, however, that while the UK depends more than ever on global navigation satellite systems (GNSS) that reliance also exposes the country to its weaknesses.
“The scale and sophistication of current and potential PNT attacks has grown (such as increased GPS signal jamming on aeroplanes) and GNSS outages could become commonplace,” the report notes. “Countries and industries that address the issue of resilience in PNT will win the time advantage.”
Telecommunication satellite services contributed £116bn to the UK in 2021/22, while Earth observation and meteorological satellite services supported industries contributing an estimated £304bn. The report calls the future of Earth observation “bold and ambitious”, with satellite data resolving “the disparities with the quality and availability of on-the-ground data, exacerbated by irregular dataset updates by governments or international agencies”.
As for future opportunities, the report highlights “in-space manufacturing”, with companies seeing “huge advantages” in making drugs, harvesting stem cells and growing crystals through in-orbit production lines. The report says that In-Orbit Servicing and Manufacturing could be worth £2.7bn per year to the UK economy but central to that vision is the need for “space sustainability”.
The report adds that the UK is “well positioned” to lead in sustainable space practices due to its strengths in science, safety and sustainability, which could lead to the creation of many “high-value” jobs. Yet this move, the report warns, demands an investment of time, money and expertise.
“This report captures the quiet impact of the space sector, underscoring the importance of the physics and the physicists whose endeavours underpin it, and recognising the work of IOP’s growing network of members who are both directly and indirectly involved in space tech and its applications,” says Alex Davies from the Rutherford Appleton Laboratory, who founded the IOP Space Group and is currently its co-chair.
Particle physicist Tara Shears from the University of Liverpool, who is IOP vice-president for science and innovation, told Physics World that future space tech applications are “exciting and important”. “With the right investment, and continued collaboration between scientists, engineers, industry and government, the potential of space can be unlocked for everyone’s benefit,” she says. “The report shows how physics hides in plain sight; driving advances in space science and technology and shaping our lives in ways we’re often unaware of but completely rely on.”
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Louisville, CO – Tendeg, a leader in advanced deployable space antennas, has received a repeat order from Capella Space, an American space tech company with synthetic aperture radar (SAR) and […]
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Cherenkov dosimetry is an emerging technique used to verify the dose delivered during radiotherapy, by capturing Cherenkov light generated when X-ray photons in the treatment beam interact with tissue in the patient. The initial intensity of this light is proportional to the deposited radiation dose – providing a means of non-contact in vivo dosimetry. The intensity emitted at the skin surface, however, is highly dependent on the patient’s skin colour, with increasing melanin absorbing more Cherenkov photons.
To increase the accuracy of dose measurements, researchers are investigating ways to calibrate the Cherenkov emission according to skin pigmentation. A collaboration headed up at Dartmouth College and Moffitt Cancer Center has now studied Cherenkov dosimetry in patients with a wide spectrum of skin tones. Reporting their findings in Physics in Medicine & Biology, they show how such a calibration can mitigate the effect of skin pigmentation.
“Cherenkov dosimetry is an interesting prospect because it gives us a completely passive, fly-on-the-wall approach to radiation dose verification. It does not require taping of detectors or wires to the patient, and allows for a broader sampling of the treatment area,” explains corresponding author Jacqueline Andreozzi. “The hope is that this would allow for safer, verifiable radiation dose delivery consistent with the treatment plan generated for each patient, and provide a means of assessing the clinical impact when treatment does not go as planned.”
Andreozzi, first author Savannah Decker and their colleagues examined 24 patients undergoing breast radiotherapy using 6 or 15 MV photon beams, or a combination of both energies.
During routine radiotherapy at Moffitt Cancer Center the researchers measured the Cherenkov emission from the tissue surface (roughly 5 mm deep) using a time-gated, intensified CMOS camera installed in the bunker ceiling. To minimize effects from skin reactions, they analysed the earliest fraction of each patient’s treatment.
Patients with darker skin exhibited up to five times lower Cherenkov emission than those with lighter skin for the same delivered dose – highlighting the significant impact of skin pigmentation on Cherenkov-based dose estimates.
To assess each patient’s skin tone, the team used standard colour photography to calculate the relative skin luminance as a metric for pigmentation. A colour camera module co-mounted with the Cherenkov imaging system simultaneously recorded an image of each patient during their radiation treatments. The room lighting was standardized across all patient sessions and the researchers only imaged skin regions directly facing the camera.
In addition to skin pigmentation, subsurface tissue properties can also affect the transmission of Cherenkov light. Different tissue types – such as dense fibroglandular or less dense adipose tissue – have differing optical densities. To compensate for this, the team used routine CT scans to establish an institution-specific CT calibration factor (independent of skin pigmentation) for the diverse patient dataset, using a process based on previous research by co-author Rachael Hachadorian.
Following CT calibration, the Cherenkov intensity per unit dose showed a linear relationship with relative skin luminance, for both 6 and 15 MV beams. Encouraged by this observed linearity, the researchers generated linear calibration factors based on each patient’s skin pigmentation, for application to the Cherenkov image data. They note that the calibration can be incorporated into existing clinical workflows without impacting patient care.
To test the impact of their calibration factors, the researchers first plotted the mean uncalibrated Cherenkov intensity as a function of mean surface dose (based on the projected dose from the treatment planning software for the first 5 mm of tissue) for all patients. For 6 MV beams, this gave an R2 value (a measure of data variance from the linear fit) of 0.81. For 15 MV treatments, R2 was 0.17, indicating lower Cherenkov-to-dose linearity.
Applying the CT calibration to the diverse patient data did not improve the linearity. However, applying the pigmentation-based calibration had a significant impact, improving the R2 values to 0.91 and 0.64, for 6 and 15 MV beams, respectively. The highest Cherenkov-to-dose linearity was achieved after applying both calibration factors, which resulted in R2 values of 0.96 and 0.91 for 6 and 15 MV beams, respectively.
Using only the CT calibration, the average dose errors (the mean difference between the estimated and reference dose) were 38% and 62% for 6 and15 MV treatments, respectively. The pigmentation-based calibration reduced these errors to 21% and 6.6%.
“Integrating colour imaging to assess patients’ skin luminance can provide individualized calibration factors that significantly improve Cherenkov-to-dose estimations,” the researchers conclude. They emphasize that this calibration is institution-specific – different sites will need to derive a calibration algorithm corresponding to their specific cameras, room lighting and beam energies.
Bringing quantitative in vivo Cherenkov dosimetry into routine clinical use will require further research effort, says Andreozzi. “In Cherenkov dosimetry, the patient becomes their own dosimeter, read out by a specialized camera. In that respect, it comes with many challenges – we usually have standardized, calibrated detectors, and patients are in no way standardized or calibrated,” Andreozzi tells Physics World. “We have to characterize the superficial optical properties of each individual patient in order to translate what the cameras see into something close to radiation dose.”
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America once led the world to the stars. Today, Congress is propping up pork barrel rocket programs while China builds the future. Here’s how we fix it — before it’s too late.
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A Senate spending bill would restore funding for dozens of NASA science missions threatened with cancellation in the administration’s 2026 budget request but is silent on one flagship program.
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The OCX software upgrade was delivered July 1 by prime contractor Raytheon
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