It’s Saturday morning and time for the usual weekly update of publications at the Open Journal of Astrophysics. This will be a short post because there is only one paper to report this week, being the 68th paper in Volume 7 (2024) and the 183rd altogether. It was published on Thursday August 15th 2024.
Here is the overlay of the paper containing the abstract:
You can click on the image of the overlay to make it larger should you wish to do so. You can also find the officially accepted version of the paper on the arXiv here.
A few months ago I posted an item about the release new results from the Dark Energy Spectroscopic Instrument (DESI). That was then followed by a presentation explaining the details which you can find here to find out more about the techniques involved. At the time the new DESI results garnered a lot of media attention much of it about claims that the measurements provided evidence for “New Physics”, such as evolving dark energy. Note that the DESI results themselves did not imply this. Only when combined with supernova measurements did this suggestion arise.
Now there’s a new preprint out by George Efstathiou of Cambridge. The abstract is here:
Recent results from the Dark Energy Spectroscopic Instrument (DESI) collaboration have been interpreted as evidence for evolving dark energy. However, this interpretation is strongly dependent on which Type Ia supernova (SN) sample is combined with DESI measurements of baryon acoustic oscillations (BAO) and observations of the cosmic microwave background (CMB) radiation. The strength of the evidence for evolving dark energy ranges from ~3.9 sigma for the Dark Energy 5 year (DES5Y) SN sample to ~ 2.5 sigma for the Pantheon+ sample. Here I compare SN common to both the DES5Y and Pantheon+ compilations finding evidence for an offset of ~0.04 mag. between low and high redshifts. Correcting for this offset brings the DES5Y sample into very good agreement with the Planck LCDM cosmology. Given that most of the parameter range favoured by the uncorrected DES5Y sample is discrepant with many other cosmological datasets, I conclude that the evidence for evolving dark energy is most likely a result of systematics in the DES5Y sample.
Here are a couple of figures from the paper illustrating the difference in parameter constraints using the uncorrected (left) and corrected (right) Dark Energy (Survey) 5 year Supernova sample.
The y-axis shows a parameter wa, which is zero in the standard model with non-evolving dark energy; the non-zero value implied by the left hand panel using the uncorrected data.
Just as with the Hubble Tension I blogged about yesterday, the evidence for a fundamental revision of our standard model may be nothing of the sort but some kind of systematic error. I think we can expect a response from the Dark Energy Survey (DES) team. Grab your popcorn.
Back in April I posted about a meeting at the Royal Society in London called Challenging the Standard Cosmological Model, some of which I attended virtually. In that post I mentioned that Wendy Freedman gave a talk related to the ongoing issue of the Hubble Tension, i.e. the discrepancy between different types of measurement of the Hubble Constant, usually characterized as local measurements (using stellar distance indicators) and larger-scale measurements (chiefly Planck). There are quite a few posts about this issue on this blog. Anyway, Wendy Freedman mention in her talk that her latest work on stellar distances suggested a value of 69.1 ± km s-1 Mpc-1, which reduces the tension with Planck significantly. At the time, however, there was no paper explaining how this number was derived.
Yesterday there appeared on arXiv a preprint by Freedman et al. which summarizes the recent results. The abstract is here:
We present the latest results from the Chicago Carnegie Hubble Program ( CCHP) to measure the Hubble constant using data from the James Webb Space Telescope (JWST). This program is based upon three independent methods: (1) Tip of the Red Giant Branch (TRGB) stars, (2) JAGB (J-Region Asymptotic Giant Branch) stars, and (3) Cepheids. Our program includes 10 nearby galaxies, each hosting Type Ia supernovae (SNe Ia), suitable for measuring the Hubble constant (H0). It also includes NGC 4258, which has a geometric distance, setting the zero point for all three methods. The JWST observations have significantly higher signal-to-noise and finer angular resolution than previous observations with the Hubble Space Telescope (HST). We find three independent values of H0 = 69.85 ± 1.75 (stat) ± 1.54 (sys) for the TRGB, H0 = 67.96 ± 1.85 (stat) ± 1.90 (sys) km s-1 Mpc-1 for the JAGB, and H0 = 72.05 ± 1.86 (stat) ± 3.10 (sys) for Cepheids. Tying into SNe Ia, and combining these methods adopting a flat prior, yields our current estimate of H0 = 69.96 ± 1.05 (stat) ± 1.12 (sys) km s-1 Mpc-1. The distances measured using the TRGB and the JAGB method agree at the 1% level, but differ from the Cepheid distances at the 2.5-4% level. The value of H0 based on these two methods with JWST data alone is H0 = 69.03 ± 1.75 (total error) km s-1 Mpc-1. These numbers are consistent with the current standard ΛCDM model, without the need for the inclusion of additional new physics. Future JWST data will be required to increase the precision and accuracy of the local distance scale.
You can read the full paper on arXiv here. A summary of the summary is that of the three methods they use, two give lower values of the Hubble constant and one (Cepheids) gives a higher value but with larger errors. The number quoted in the Royal Society talk was presumably preliminary as it doesn’t match any of the numbers in the abstract, but the point remains.
You can see the reduction in scatter in the new JWST measurements in this Figure (old on the left and new on the right).
On the face of it, these results suggest that the Hubble tension is greatly reduced. I am sure, however, that advocates of a higher value will have been preparing their ripostes and it’s just a matter of time before they arrive on the arXiv too!
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.
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, 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.
, 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.
I’ve just heard the 
In the Dark 