One of the many highlights of the 2024 Olympics was the amazing achievement of Armand Duplantis in winning the Gold Medal in Pole Vault and in the process breaking his own world record at a height of 6.25m. Here he is
He seemed to clear that height quite comfortably, actually, so I dare say he’ll break quite a few more records in his time. On the other hand, when I first wrote about this back in 2011 the world record for the pole vault was held by the legendary Ukrainian athlete Sergey Bubka at a height of 6.14m which he achieved in 1994. That record stood for almost 20 years but has since been broken several times since. The fact that the world record has only increased by 11 cm in 30 years tells you that the elite pole vaulters are working at the limits of what the human body can achieve. A little bit of first-year mechanics will convince you why, as I have pointed out in previous posts (e.g. here).
What a pole-vaulter does is rather complicated and requires a lot of strength, flexibility and skill, but as in many physics problems one can bypass the complications and just look at the beginning and the end and use an energy conservation argument. Basically, the pole is a device that converts the horizontal kinetic energy of the vaulter , as he/she runs in, to the gravitational potential energy acquired at the apex of his/her vertical motion, i.e. at the top of the vault.
Now assume that the approach is at the speed of a sprinter, i.e. about , and work out the height that the vaulter can gain if the kinetic energy is converted with 100% efficiency. Since the answer to that little sum turns out to be about 5 metres.
This suggests that 6.25 metres should not just be at, but beyond, the limit of a human vaulter, unless the pole were super-elastic. However, there are two things that help. The first is that the centre of mass of the combined vaulter-plus-pole does not start at ground level; it is at a height of a bit less than 1m for an an average-sized person. Note also that the centre of mass of pole (which weighs about 15 kg and is about 5 m long) only ends up about 2.5 m off the ground when it is vertical, so there’s a significant effect there. Note also that the centre of mass of the vaulter does not actually pass over the bar after letting go of the pole. That doesn’t happen in the high jump, either. Owing to the flexibility of the athlete’s back, the arc is such that the centre of mass remains under the bar while the different parts of the athlete’s body go over it.
Moreover, it’s not just the kinetic energy related to the horizontal motion of the vaulter that’s involved. A human can jump vertically from a standing position using elastic energy stored in muscles. In fact the world record for the standing high jump is an astonishing 1.9m. In the context of the pole vault it seems likely to me that this accounts for at least a few tens of centimetres.
Despite these complications, it is clear that pole vaulters are remarkably efficient athletes. And not a little brave either – as someone who is scared of heights I can tell you that I’d be absolutely terrified being shot up to 6.25 metres on the end of a bendy stick, even with something soft to land on!
It’s Saturday so it’s time once again for another roundup of business at the Open Journal of Astrophysics. After last week’s summer lull, this week I have three papers to announce, which brings the total we have published so far this year (Vol. 7) to 67 and the total published by OJAp to 182.
First one up, published on 7th August 2024, is “Brightest Cluster Galaxy Offsets in Cold Dark Matter” by Jonathan Katz of Washington University (St Louis, Missouri, USA), a simulation-based study of the distribution of the position of brightest cluster galaxies relative to the dark matter distribution and its possible use as a cosmological probe. The authors are Cian Roche (MIT), Michael McDonald (MIT), Josh Borrow (MIT), Mark Vogelsberger (MIT), Xuejian Shen (MIT), Volker Springel (MPA Garching), Lars Hernquist (Harvard), Ruediger Pakmor (Harvard), Sownak Bose (Durham, UK) and Rahul Kannan (York U., Canada). This paper is in the folder marked Astrophysics of Galaxies.
Here is a screen grab of the overlay, which includes the abstract:
The second paper to present is “LAMOST J1010+2358 is not a Pair-Instability Supernova Relic” by five authors based in the USA: Pierre Thibodeaux (Chicago), Alexander P. Ji (Chicago), William Cerny (Yale), Evan N. Kirby (Notre Dame) and Joshua D. Simon (Carnegie Observatories) . As the title makes clear, the paper presents arguments against previous claims that a particular star is not a pair-instability supernova relic. This paper is in the folder marked Solar and Stellar Astrophysics. It was published on Friday August 9th 2024.
The overlay looks like this:
You can read this paper directly on the arXiv here.
Last, but by no means least, comes “A Pilot Search for Gravitational Self-Lensing Binaries with the Zwicky Transient Facility“, results of a trial search for signals of gravitational lensing of one component in a binary system by a compact companion, with a discussion of future prospects for larger surveys. This one, which was also published on 9th August, is in the folder marked High-Energy Astrophysical Phenomena. The authors are Allison Crossland & Eric C Bellm (U. Washington), Courtney Klein (UC Irvine), James R. A. Davenport (U. Washington), Thomas Kupfer (Hamburg Observatory) and Steven L. Groom, Russ R. Laher & Reed Riddle (Caltech).
Here is a screengrab of the overlay:
To read the accepted version of this on the arXiv please go here.
That’s it for this week. I hope to post another update next weekend.
As I’ve mentioned before on this blog, one of my English teachers at school would occasionally give us exercises in creative writing inspired by `Only Connect’ – the epigraph of the novel Howard’s End by E.M. Forster. We were given two apparently disconnected things (usually news items), asked to think of a possible connection between them and write an story joining them together. From time to time when trying to think of something to write about I’ve resorted to playing the same game and am going to do it today.
Tsung-Dao Lee’s most famous work – for which he won the 1957 Nobel Prize with was on parity violation, which was detected experimentally by Chien-Shiung Wu in 1956. Parity is a conserved quantity in classical physics (e.g. in electromagnetism and gravity) and it was believed until the mid-20th century that it would be conserved in the quantum theory of nuclear interactions too. Wolfgang Pauli, for example, criticized Hermann Weyl’s suggestion of a two-component weakly interacting massless particle because it implied parity violation.
The experimental proof of parity violation in some weak interactions led to a much deeper understanding of fundamental physics, including the the idea of chiral gauge interactions, and the development of the standard model of particle physics. Parity is violated in some strong interactions too. Our simple-minded view of how things are changed as a result of an exception to a widely-held assumption. That’s how progress happens.
You might think now that I’m going to write about the fact that double-helix structure of DNA is right-handed, i.e. that it exhibits a form of parity violation, but that’s not it. Or only a little bit. You see, not all DNA is right-handed…
What does this have to do with Olympic boxing? Well, much of the furore about about Imane Khelif is about the (unproven) assertion that she has XY chromosome and is therefore male and should not be allowed to box in the women’s competition. A ‘biological’ female would have XX chromosomes.
It is true in the vast majority of cases that men have XY chromosomes and women have XX chromosomes, but if you read any reasonably modern book on human biology, the statement that ‘females have XX chromosomes’ is preceded by a “usually” or “in most cases”. But there exceptions: some women have XY chromosomes and some men have XX chromosomes; there are also individuals who have an extra chromosome and are XXY.
How can a person be said to be female if they have XY chromosomes? Well, that is because there is a very long journey between the information encoded in genetic material and the expression of that information in form and function. That entire process determines whether an athlete may nor not have an advantage over another. In a rare, sensible article about the Imane Khelif case I found this
Alun Williams, professor of sports and exercise genomics at Manchester Metropolitan University, said that when considering if a person had an unfair advantage it was necessary to look at chromosomes, levels of testosterone and other hormones, as well as the body’s response to testosterone.
“That then is a clinical assessment, which is really very invasive,” Williams said. “Simply looking at someone’s sex chromosomes … is incomplete.”
In most cases individuals with XY chromosomes develop “male” characteristics and those with XX chromosomes develop “female” but there are exceptions. For example, there are women – with ovaries, a uterus and no male sex organs – who have XY chromosomes. These are biologically female, even if their karyotype indicates otherwise. There is much more to biology than genetics, just as there is much more to physics than electromagnetism and gravity.
I don’t know whether Imane Khelif has XY chromosomes or not, and frankly I don’t care. The fact is that she was assigned female gender at birth, has been raised as female, and her gender is female as on her passport. She is a woman. I won’t use the phrase biological woman, because it is silly: every human being is biological. Caster Semenya is female too.
You might not care about this case and prefer top stick to the rigid definition that XX=male and XY=female. I don’t think that’s appropriate in sports: chromosomes don’t compete in sports, people do. I’ve also been accused of being ‘unscientific’ for accepting that the exceptions to a rule. On the contrary, I think such exceptions are how our understanding improves, not only in scientific terms but also in our respect for our fellow human beings.
I’ve just heard the sad news of the death at the age of 97 of TD Lee (shown left) who, together with CN Yang, won the Nobel Prize for Physics in 1957 for his work on parity violation in particle physics. I always find it difficult on occasions like this to find ways of describing the work of people of such eminence in fields other than my own, but in this case it turns out I have a personal connection of a sort. Way back in 2006 when I was at Nottingham, the University decided to award Prof. Lee an honorary degree and I was chosen to deliver the oration at the graduation ceremony before spending some time chatting to him with some students. I remember that it was a very hot day and I was wilting under the graduation robes, but he took it all in his stride despite being 80 years old. Anyway, here is the text that I prepared for that occasion, which I hope will serve as a fitting obituary.
PROFESSOR TSUNG-DAO LEE
ORATION DELIVERED BY PROFESSOR PETER COLES
ON MONDAY 17 JULY 2006
Chancellor, Vice-Chancellor, Ladies and Gentlemen, it is both a pleasure and a privilege to present Professor Tsung-Dao Lee for the award of an honorary degree. Professor Lee is a distinguished theoretical physicist whose work over many years has been characterized, in the words of Dr J Robert Oppenheimer, by “a remarkable freshness, versatility and style.”
Tsung-Dao Lee was born in Shanghai and educated at Suzhou University Middle School in Shanghai. Fleeing the Japanese invasion, he left Shanghai in 1941. His education was interrupted by war. In 1945 he entered the National Southwest University in Kunming as a sophomore. He was soon recognized as an outstanding young scientist and in 1946 was awarded a Chinese Government Scholarship enabling him to start a PhD in Physics under Professor Enrico Fermi at the University of Chicago. He gained his doctorate in physics in 1950 with a thesis on the Hydrogen Content of White Dwarf Stars, and subsequently served as a research associate at the Yerkes Astronomical Observatory of the University of Chicago in Williams Bay, Wisconsin.
Astronomy is a science that concerns the very large, but it was in the physics of the very small that Professor Lee was to do his most famous work. After one year as a research associate and lecturer at the University of California in Berkeley, he became a fellow of the Institute of Advanced Study in Princeton and, in 1953, he accepted an assistant professorship position at Columbia University in New York. Two and a half years later, he became the youngest full professor in the history of Columbia University. During this time he often collaborated with Chen Ning Yang whom he had known as a fellow student in Chicago. In 1956 they co-authored a paper whose impact was both immediate and profound. Only a year later, Lee and Yang were jointly awarded the Nobel Prize in Physics. Professor Lee was thirty-one at the time and was the second youngest scientist ever to receive this distinction. (The youngest was Sir Lawrence Bragg who shared the Physics Prize with his father in 1915, at the age of twenty-five; Werner Heisenberg was 31 when his Nobel Prize was announced, in 1932, but he did not receive the prize until the following year.)
It is usually difficult to explain the ideas of theoretical physics to non-experts. The mathematical language is inaccessible to those without specialist training. But some of the greatest achievements in this field are so bold and so original that they appear, at least with hindsight, to be astonishingly simple. The work of Lee and Yang on parity violation in elementary particle interactions is an outstanding example.
Subatomic particles interact with each other in very complicated ways. In high energy collisions, particles can be scattered, destroyed or transformed into other particles. But governing these changes are universal rules involving things that never change. The existence of these conservation laws is a manifestation of the symmetries possessed by the mathematical theory of particle interactions.
Lee and Yang focussed on a particular attribute called parity, which relates to the “handedness” of a particle and symmetry with respect to mirror reflections. Physicists had previously assumed that the laws of nature do not distinguish between left- and right-handed states: a left-handed object when seen in a mirror should be indistinguishable from a right-handed one. This symmetry suggests that parity should be conserved in particle interactions, as it is in many other physical processes. Unfortunately this chain of thought led to a puzzling deadlock in our understanding of the so-called weak nuclear interaction. Lee and Yang made the revolutionary suggestion that parity is not conserved in weak interactions and consequently that the laws of nature must have a built-in handedness. A year later their theory was tested experimentally and found to be correct. Their penetrating insight led to a radical overhaul of the theory of weak interactions and to many further discoveries. Physicists around the world said “Of course! Why didn’t I think of that?”
This classic “Eureka moment” happened half a century ago, but Professor Lee has since made a host of equally distinguished contributions to fields as diverse as astrophysics, statistical mechanics, field theory and turbulence. He was made Enrico Fermi Professor at Columbia in 1964 and University Professor there in 1984. With typical energy and enthusiasm he took up the post of director of the RIKEN Research Center at Brookhaven National Laboratories in 1998. He has played a prominent role in the advancement of science in China, including roles as director of physics institutes in Beijing and Zhejiang.
Professor Lee has received numerous awards and honours from around the world, including the Albert Einstein Award in Science, the Bude Medal, the Galileo Galilei Medal, the Order of Merit, Grande Ufficiale of Italy, the Science for Peace Prize, the China National-International Cooperation Award, the New York City Science Award, the Pope Joannes Paulis Medal, Il Ministero dell’Interno Medal of the Government of Italy and the New York Academy of Sciences Award. His recognition even extends beyond this world, for in 1997 Small Planet 3443 was named in his honour.
Chancellor, Vice-Chancellor, to you and to the whole congregation I present Professor Tsung-Dao Lee as eminently worthy to receive the degree of Doctor of Science, honoris causa.
I’ve managed to cross another one off the list of books I’ve had for ages but never read, in the form of biochemist Nick Lane‘s The Vital Question I bought this book several years ago and have no idea why I took so long to get around to it. Given how quickly things are moving in the biosciences these days, it may even be a bit out of date now, but as far as I’m concerned it’s better late than never.
I haven’t studied biology since O-level (1979) but did chemistry as one of four subjects in the first year year of Natural Sciences at Cambridge and I remember some organic chemistry. I wish I had done Biology of Cells then, though, not because I would have carried on with it but because it’s much more interesting than the subject I did take, Crystalline Materials. Probably much of what I would have learnt in 1982-3 is out of date now.
The Vital Question doesn’t ask a single big question but tackles a number of interrelated questions that together comprise a big mystery in the origin of life, basically the apparently sudden appearance of eukaryotic life (i.e. organisms with complex cells, including plants and animals) as distinct from simpler the forms, archaea and bacteria. Among the fascinating issues are how eukaryotes evolved, why there is no missing link, and why eukaryotic cells are all built on a similar model, what made reproductive sex the way it is, and why in the midst of life there has to be death.
One of the great advances in biosciences since the time I didn’t study it is a revolution in the understanding and practical application of genetics, especially through fast DNA sequencing, not only in biology but also in other fields such as medicine, archaeology and forensic science. One of the valuable points that Lane makes is that the success of genetics led to an emphasis on the role of information – because that’s what genes represent – to the detriment of other essential factors in living cells, especially energy. The book points to the relationship, familiar to physicists, that information relates to entropy, but makes it clear that entropy on its own is not sufficient to understand the thermodynamics of, e.g., respiration and reproduction.
This is a recurrent theme in the history of science, actually, that the success of one particular way of looking at phenomenon often seems to convince people that it provides the complete picture, when some subsequent study demonstrates that usually turns out not to be the case. None of this is to argue that genes are unimportant. They undoubtedly are, but so are other factors including reaction kinetics and environment.
Anyway, to address this big question, Lane gives us a tour of the processes involved at a significant level of complexity but the book is so well-written that it’s actually a bit of a page-turner. As I explained at the beginning I haven’t studies any biology for over 40 years so I struggled at first with some of the technical words, but there is a full glossary to help. The rather dreary pictures are less helpful, but altogether is a superb introduction.
One of the aspects of this book I enjoyed greatly is the number of digressions. That might put some people off, but I thought it helped to paint a true picture of the richness of life in all its forms as well the constraints imposed on it. I didn’t know for example that while most mammals (including humans) have X or Y chromosomes, birds are different: they have W and Z (note to physicists: not to be confused with the gauge bosons). Moreover, while the reproductive sex usually indicated by XX is female (homomorphic) and XY is male (heteromorphic), the opposite is true for birds and some reptiles: females are heteromorphic (ZW) and males are homomorphic (ZZ). Why this difference arose I have no idea, but Lane makes some interesting observations about how it may be behind how some male birds develop exaggerated pigmentation and plumage.
Another question that struck me reading this book is why the human genome is so small. Or rather, why so many other genomes are much bigger. For reasons I described in a post a few years ago, I actually have a CD with my own genome on it. Come to think of it, I no longer have a CD drive so have no way of reading it. Anyway, the human comprises about 3 billion base pairs. Some apparently much simpler organisms have genomes much larger than that. We humans are much simpler than we tend to think! Why is that?
Obviously it has been my turn to digress…
I thoroughly recommend this book for a number of reasons, including the excellent explanations of biochemical processes and the fact that it’s written with such obvious enthusiasm and desire to communicated. Above all, though, Lane does what a scientist should do, i.e. he’s honest about the huge gaps in our knowledge. He doesn’t pretend to answer all the questions he asks, but demonstrates the importance of tackling the big issues head on and acknowledging what is known, what is unknown, and what is speculation. That’s a lesson for all science communicators!
Today sees the launch of a new initiative between Galaxy Zoo (part of the Zooniverse conglomerate) and the Euclid Consortium which I am delighted to be able to promote on this blog. What follows the graphic is the text of the announcement which is being promoted across social media today. I’ll start with a little factoid which might surprise you: already in November 2023, before science operations even began, Euclid had sent back to Earth more data than the Hubble Space Telescope has done in in its entire lifetime.
Thanks to a new Galaxy Zoo project launched today, you can help identify the shapes of thousands of galaxies in images taken by ESA’s Euclid space telescope. These classifications will help scientists answer questions about how the shapes of galaxies have changed over time, and what caused these changes and why.
In its mission to map out the Universe, Euclid will image hundreds of thousands of distant galaxies. In November 2023 and May 2024, the world got its first glimpse at the quality of Euclid’s images, which included a variety of sources, from nearby nebulas to distant clusters of galaxies. In the background of each of these images are hundreds of thousands of distant galaxies.
This square astronomical image shows thousands of galaxies across the black expanse of space. The closest thousand or so galaxies belong to the Perseus Cluster.
For the next six years, the spacecraft is expected to send around 100 GB of data back to Earth every day. That’s a lot of data, and labelling that through human effort alone is incredibly difficult.
That’s why ESA and Euclid consortium scientists have partnered with Galaxy Zoo. This is a citizen science project on the Zooniverse platform, where members of the public can help classify the shapes of galaxies.
Euclid will release its first catalogues of data to the scientific community starting in 2025, but in the meantime any volunteer on the Galaxy Zoo project can have a glimpse at previously unseen images from the telescope.
You could be the first person to lay eyes on a galaxy
The first set of data, which contains tens of thousands of galaxies selected from more than 800 000 images, has been made available on the platform, and is waiting for you to help classify them.
If you partake in the project, you could be the first to lay eyes on Euclid’s latest images. Not only that, you could also be the first human ever to see the galaxy in the image.
The Galaxy Zoo project was first launched in 2007, and asked members of the public to help classify the shapes of a million galaxies from images taken by the Sloan Digital Sky Survey. In the past 17 years, Galaxy Zoo has remained operational, with more than 400 000 people classifying the shapes of galaxies from other projects and telescopes, including the the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope.
Humans and AI working together
These classifications are not only useful for their immediate scientific potential, but also as a training set for Artificial Intelligence (AI) algorithms. Without being taught what to look for by humans, AI algorithms struggle to classify galaxies. But together, humans and AI can accurately classify limitless numbers of galaxies.
At Zooniverse, the team has developed an AI algorithm called ZooBot, which will sift through the Euclid images first and label the ‘easier ones’ of which a lot of examples already exist in previous galaxy surveys. When ZooBot is not confident on the classification of a galaxy, perhaps due to complex or faint structures, it will show it to users on Galaxy Zoo to get their human classifications, which will then help ZooBot to learn more.
On the platform, volunteers will be presented with images of galaxies and will then be asked several questions, such as “Is the galaxy round?”, or “Are there signs of spiral arms?”.
After being trained on these human classifications, ZooBot will be integrated in the Euclid catalogues to provide detailed classifications for hundreds of millions of galaxies, making it the largest scientific catalogue to date, and enabling groundbreaking new science.
This project makes use of the ESA Datalabs digital platform to generate a large number of cutouts of galaxies imaged by Euclid.
Thanks to a new Galaxy Zoo project launched today, you can help identify the shapes of thousands of galaxies in images taken by ESA’s Euclid space telescope. These classifications will help scientists answer questions about how the shapes of galaxies have changed over time, and what caused these changes and why.
The first set of data, which contains tens of thousands of galaxies selected from more than 800 000 images, has been made available on the platform, and is waiting for you to help classify them.
Examples of Euclid galaxies to classify are shown in this image.
Euclid Galaxy Zoo galaxies to classify. Forty galaxies are shown against a black background. The galaxies are all different in shape, some look like spirals, some look barred, or smooth. Image credit: ESA/Euclid/Euclid Consortium/NASA, CC BY-SA 3.0 IGO or ESA Standard Licence
Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium – consisting of more than 2000 scientists from 300 institutes in 15 European countries, the USA, Canada and Japan – is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. NASA provided the detectors of the Near-Infrared Spectrometer and Photometer, NISP. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.
Looking at the title of this paper you might be tempted to dismiss it on the grounds that warp drives are the stuff of science fiction (which they are), but this paper is really a rigorous technical study of the dynamical evolution and stability of spacetimes that violate the null energy condition, inspired by the idea of a warp drive. As soon as I announced this paper on social media it started to get attention. That will probably increase because there is now a press release to accompany the paper. I’ve taken the liberty of reproducing the text of the press release here:
–o–
Imagine a spaceship driven not by engines, but by compressing the spacetime in front of it. That’s the realm of science fiction, right? Well, not entirely. Physicists have been exploring the theoretical possibility of “warp drives” for decades, and a new study published in the Open Journal of Astrophysics takes things a step further – simulating the gravitational waves such a drive might emit if it broke down.
Warp drives are staples of science fiction, and in principle could propel spaceships faster than the speed of light. Unfortunately, there are many problems with constructing them in practice, such as the requirement for an exotic type of matter with negative energy. Other issues with the warp drive metric include the potential to use it to create closed time-like curves that violate causality and, from a more practical perspective, the difficulties for those in the ship in actually controlling and deactivating the bubble.
This new research is the result of a collaboration between specialists in gravitational physics at Queen Mary University of London, the University of Potsdam, the Max Planck Institute (MPI) for Gravitational Physics in Potsdam and Cardiff University. Whilst it doesn’t claim to have cracked the warp drive code, it explores the theoretical consequences of a warp drive “containment failure” using numerical simulations.
Dr Katy Clough of Queen Mary University of London, the first author of the study explains: “Even though warp drives are purely theoretical, they have a well-defined description in Einstein’s theory of General Relativity, and so numerical simulations allow us to explore the impact they might have on spacetime in the form of gravitational waves.”
Co-author Dr Sebastian Khan, from Cardiff University’s School of Physics and Astronomy, adds: “Miguel Alcubierre created the first warp drive solution during his PhD at Cardiff University in 1994, and subsequently worked at the MPI in Potsdam. So it’s only natural that we carry on the tradition of warp drive research in the era of gravitational wave astronomy .”
The results are fascinating. The collapsing warp drive generates a distinct burst of gravitational waves, a ripple in spacetime that could be detectable by gravitational wave detectors that normally target black hole and neutron star mergers. Unlike the chirps from merging astrophysical objects, this signal would be a short, high-frequency burst, and so current detectors wouldn’t pick it up. However, future higher-frequency instruments might, and although no such instruments have yet been funded, the technology to build them exists. This raises the possibility of using these signals to search for evidence of warp drive technology, even if we can’t build it ourselves.
Dr Khan cautions “In our study, the initial shape of the spacetime is the warp bubble described by Alcubierre. While we were able to demonstrate that an observable signal could in principle be found by future detectors, given the speculative nature of the work this isn’t sufficient to drive instrument development.”
The study also delves into the energy dynamics of the collapsing warp drive. The process emits a wave of negative energy matter, followed by alternating positive and negative waves. This complex dance results in a net increase in the overall energy of the system, and in principle could provide another signature of the collapse if the outgoing waves interacted with normal matter.
This research pushes the boundaries of our understanding of exotic spacetimes and gravitational waves. Prof Dietrich comments: “For me, the most important aspect of the study is the novelty of accurately modelling the dynamics of negative energy spacetimes, and the possibility of extending the techniques to physical situations that can help us better understand the evolution and origin of our universe, or the avoidance of singularities at the centre of black holes.”
Dr Clough adds: “It’s a reminder that theoretical ideas can push us to explore the universe in new ways. Even though we are sceptical about the likelihood of seeing anything, I do think it is sufficiently interesting to be worth looking!”
The researchers plan to investigate how the signal changes with different warp drive models and explore the collapse of bubbles travelling at speeds exceeding the speed of light itself. Warp speed may be a long way off, but the quest to understand the universe’s secrets continues, one simulated crash at a time.
It’s Saturday morning, so once again it’s time for an update of activity at the Open Journal of Astrophysics. This week we have published another batch of four papers, the same number as last week, which takes the count in Volume 7 (2024) up to 64 and the total published altogether by OJAp up to 179.
Before announcing the week’s papers I’ll add three other updates you might find interesting:
When I looked at NASA/ADS this morning to help construct this post I saw that papers published in OJAp have now garnered over 2500 citations between them;
Last week we received a significant (unsolicited) cash donation from a higher education institution based in Europe to help with our work in Diamond Open Access. If any other organizations or individuals would like to do similar then please contact me!
Now, in chronological order, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
First one up is: “Widespread disruption of resonant chains during protoplanetary disk dispersal by Bradley M S Hansen (UCLA), Tze-Yeung Yu (UCLA) and Yasuhiro Hasegawa (JPL), all based in California, USA. The paper presents a discussion of the effect of a dispersing protoplanetary disk on the evolution of low-mass planets around a Solar mass star. It was published on 21st July 2024 and is in the folder marked Earth and Planetary Astrophysics.
Here is a screen grab of the overlay, which includes the abstract:
You can find the officially accepted version of the paper on the arXiv here.
The second paper to announce is “Using A One-Class SVM To Optimize Transit Detection” by Jakob Roche of the University of South Florida, also in the USA (but not in California). This articles discusses the advantages of One-Class Support Vector Machines (SVMs) over Convolutional Neural Networks (CNN) in the context of exoplanet detection. Its in the folder called Instrumentation and Methods for Astrophysics and was published on 25th July 2024.
You can see the overlay here:
The accepted version of this paper can be found on the arXiv here.
The next paper, also published on 25th July 2024, is in the folder marked High-Energy Astrophysical Phenomena. Its primary classification on arXiv is General Relativity and Quantum Cosmology (gr-qc), but it is cross-listed on astro-ph so we considered it for publication and had it refereed, with favourable results. It is entitled “What no one has seen before: gravitational waveforms from warp drive collapse” and is by Katy Clough (QMUL, UK), Tim Dietrich (Potsdam, Germany) and Sebastian Khan (Cardiff, UK). Looking at the title of this paper you might be tempted to dismiss it on the grounds that warp drives are the stuff of science fiction (which they are), but this paper is really a rigorous technical study of the dynamical evolution and stability of spacetimes that violate the null energy condition, inspired by the idea of a warp drive.
Here is the overlay:
You can find the full text for this one on the arXiv here.
Last, published on 26th July 2024, we have a paper with the title “A study of gamma-ray emission from OJ 287 using Fermi-LAT from 2015-2023” by Vibhavasu Pasumarti and Shantanu Desai of the Indian Institute of Technology, Hyderabad, India. It is an investigation of the properties of gamma-ray emission from OJ287 (a BL Lac object) using the Fermi Large Area Telescope (LAT). This one is also in the folder marked High-Energy Astrophysical Phenomena; here is the overlay
You can find the officially accepted version of this paper on the arXiv here.
That’s all for this week. Stay tuned for another update next week.
I just realized that I had forgotten to give notice of an important scheme run jointly between the Royal Society and Science Foundation Ireland that gives early career researchers in Ireland access to University Research Fellowships. In previous years I’ve passed this on ahead of the opening of the scheme, but it is already open. In fact there was a Zoom webinar for Irish applicants on 17th July, which has now passed. The deadline is not until 10th September, however, so there is time to apply.
This scheme provides eight years of research funding and has proved to be a stepping stone to their first permanent academic position for a great many scientists. Here are a couple of items about the eligibility and duration.
Eligibility: The scheme is open to early career Post Doctoral Researchers with between 3-8 years of actual research experience since their PhD (date on which the degree was approved by board of graduate studies) by the closing date. You cannot apply if you hold a permanent post in a university.
Funding and Duration: Once upon a time this scheme provided funding of the research fellow’s salary and research expenses for an initial period of 5 years with the possibility to apply for a further 3 years. A couple of years ago this changed, however, and applicants are now asked to provide a proposal for a project lasting eight years which is subject to a mid-term review.
Key Dates: Applications need to be in by 3pm 10th September 2024 at 3pm UK time.
For further details and further developments see here.
The scheme covers a wide range of disciplines. including physics and astronomy. Of course if you want to do cosmology, either observational or theoretical, the best place to do it in Ireland is here in Maynooth but we also do, e.g. condensed matter theory and particle physics.
The deadline is not far off, so please get cracking. You will need to get a statement of support from the relevant Head of Department at your chosen institution, so you need to make contact with your prospective host as soon as possible.
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