Monthly Archives: August 2021

Your teacher was wrong! Its a phrase many a high school or university student has heard. As practising and former science teachers, we have been challenged with this accusation before.

Whereas those with advanced science understanding (including the students lecturers and high school teachers) may well say their previous teachers were wrong, incomplete might be more appropriate. These teachers were probably right in selecting age-appropriate scientific models and teaching these in age-appropriate ways.

If we were to put Einstein in front of a year 7 class, he might well present content to those students way beyond their level of understanding. This highlights a common misunderstanding of what is (and isnt) taught in schools, and why.

Our cognitive development, defined by different stages according to age, means learning is gradual. Teaching involves choosing the right pedagogies to impart knowledge and skills to students in a manner that matches their cognitive development.

In this article, we will use understanding of forces in science to demonstrate this gradual progression and evolution of education.

In Australian schools, forces are taught from kindergarten (foundation) to year 12. Throughout their education, and especially in primary education despite the various challenges, it is more important that students learn science inquiry skills than simply science facts. This is done within the contexts of all science topics, including forces.

Read more: Five challenges for science in Australian primary schools

Before a child can learn about the science of the world around them they must first acquire language skills through interactions with adults such as book reading (particularly picture books).

In preschool and kindergarten, play-based learning using early years learning principles is particularly important. Dropping objects such as rocks and feathers to see which falls faster, or what sinks, might lead to comments like heavy things fall faster or heavy things sink. Of course, this is wrong since air resistance is not being considered, or density relative to water, but it is is right for five-year-old children.

At this age, they are learning to make observations to make sense of the world around them through curious play. Children may lack a full understanding of complicated topics until they are capable of proportional reasoning.

In junior high school, students learn about Newtons Laws of Motion through various experiments. These typically use traditional equipment such as trolleys, pulleys and weights, as well as online interactives.

In senior years, students examine uniform acceleration and its causes. As well as performing first-hand investigations, such as launching balls in the air and using video analysis, students need higher mathematical skills to deal with the algebra involved. Strictly speaking, they should take into account friction, but ignoring it is normal at this level.

Online simulations are particularly good for this topic. Our research has shown simulations can have a statistically significant and positive effect on student learning, particularly with the student-centred opportunities they present. (They are also very useful while learning from home in lockdown.)

Have a go at the simulation below.

Read more: Students with laptops did better in HSC science

Students then extend their learning to Newtons Universal Law of Gravitation. Students now need to apply higher mathematical skills, with further algebra and potentially calculus. Although this model is incomplete, and cannot explain the orbit of Mercury (among other things), this knowledge was enough to get us to the Moon and back.

Getting beyond Newtonian physics and its limitations, undergraduate students learn Einsteins General Theory of Relativity where gravity is not thought of as a force between two objects, but as the warping of spacetime by masses. To tackle this content, students need the mathematical prowess to solve Einsteins nonlinear field equations.

So have we finally reached the correct view? No, general relativity does not provide a complete explanation. Theoretical physicists are working on a quantum theory of gravity. Despite a century of searching, we still have no way to reconcile gravity and quantum mechanics. Even this is an unfinished model.

Read more: Approaching zero: super-chilled mirrors edge towards the borders of gravity and quantum physics

Teachers arent wrong, they are being appropriately incomplete, just as Einstein was incomplete. So how can we avoid such accusations?

Perhaps the answer lies in the language we use in the classroom. Rather than say This is how it is we should instead say One way of looking at it is , or One way to model this is , not as a matter of opinion, but as a matter of complexity. This allows the teacher to discuss the model or idea, while hinting at a deeper reality.

Is Einstein actually wrong? Of course not, but it is important to realise that our models of forces and gravity are incomplete, as with most of science, hence the academic pursuit of higher knowledge.

More importantly, our teachers understand the process of introducing students to increasingly sophisticated models so they better understand the universe we live in. This matches their cognitive development through childhood.

Learning is a journey, not simply the end point. As the aphorism attributed to Einstein states, Everything should be as simple as it can be, but not simpler.

This article was co-authored by Paul Looyen, Head of Science at Macarthur Anglican School and Content Creator at PhysicsHigh.

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Einstein was 'wrong', not your science teacher - M - The Conversation AU

It's hard to understate the genius of Albert Einstein. As one of the world's foremost physicists, his discoveries revolutionized the way we see not just our world but the entirety of the universe. It's little wonder how the name Einstein has come to be synonymous with scientific genius.

He is most well known for his theory of relativity, but his brilliance did not end there. He helped lay the foundations for quantum mechanics with his Nobel Prize-winning work on the photoelectric effect and was instrumental in bringing the world into the atomic age, though was generally opposed to the use of nuclear weapons.

By pushing our understanding of physics far beyond what anyone thought possible or could even imagine at the time, Einstein stands nearly alone in the pantheon of physicists with his unparalleled brilliance.

Albert Einstein was born on March 14, 1879, to Hermann Einstein and Pauline Koch-Einstein, Ashkenazi Jews living in Ulm, the Kingdom of Wrttemberg in the southern part of the German Empire.

Shortly after his birth, his family moved to Munich, where his father and uncle founded an electrical equipment manufacturing company. Einstein began receiving a primary education at a Catholic school in 1885 before transferring to the Luitpold-Gymnasium (since renamed the Albert Einstein Gymnasium, for obvious reasons) in 1888.

Einstein was, surprisingly or maybe not so surprisingly, a mediocre student. So mediocre in fact that when Einstein wanted to attend theEidgenoessische Polytechnische Schule (mercifully renamed ETH in later years) in Zurich, Switzerland, in 1895, he failed the entrance examination and had to attend the Kantonschule in Aarau, Switzerland, to remediate the subject areas whose test scores were insufficient.

Receiving a diploma from the school in 1896, he was able to enroll in ETH soon thereafter with the goal of becoming a math and physics teacher. Again, he was a passable student, but not much more than that, though he did manage to graduate with a diploma in July 1901.

By this point, he had already abandoned his German citizenship and had been formally granted Swiss citizenship in February 1901. He spent several months looking for a job, giving private instruction in math and physics to make ends meet, and taking short-term employment as a teacher from May 1901 to January 1902.

Albert Einstein's turn as the world's most famous patent clerk started with the help of a fellow student, Marcel Grossman, who helped get Einstein a probationary appointment at the Swiss Patent Office in Bern, where he had settled after school.

Einstein took up the position in December 1901 and by June 1902, he was promoted to Technical Expert, Third Class, giving him some measure of stability, and allowing him to pursue his research in theoretical physics.

At this time, he was also a founding member of the Akademie Olympia, a scientific society in Bern that greatly helped focus Einstein's work and thinking in the field of physics.

In April 1905, Einstein submitted a doctoral thesis to the University of Zurich titled, "A New Determination of Molecular Dimensions" which he had dedicated to Grossman. It was accepted by the University in July of that year, but by then Einstein was already well on his way to revolutionizing our understanding of the universe.

To say that the year 1905 was a landmark year for science is grossly underselling it. Einstein, still working as a "technical expert" in the Swiss patent office, published four revolutionary scientific papers in a span of just 7 months that would establish him as one of the greatest scientific minds of the time. Einstein later described the period by saying thatit was when a storm broke loose in my mind.

The first of the papers was "On A Heuristic Point of View Concerning the Production and Transformation of Light," which was the first paper to theorize that electromagnetic radiation, including light, consisted of "quanta".

The paper argued that, in effect, radiation was carried through space by means of measurable particles which we know today as photons. Interestingly, this theory was rejected at first before it was eventually confirmed by Max Planck, who was initially critical of the theory himself. For this discovery, Einstein would win the 1921 Nobel Prize for Physics.

The next paper was publishedon July 18, 1905, titled,On the movement of small particles suspended in a stationary liquid, as required by the molecular-kinetic theory of heat.Although it did not revolutionize the principles of physics, Einstein demonstrated through the physical phenomenon of Brownian motion empirical evidencethat matter is composed of atoms.Although many scientists already believed this, it was by no means universally accepted.Einstein not only mathematically confirmed the existence of atoms and molecules but also opened a new field in the study of physics,statistical physics.

Einstein wasn't done, however. His next paper, "On theElectrodynamics of Moving Bodies", and published in September 1905, was the most groundbreaking. It introduced the idea of Special Relativity, which addresses the problem of objects in different coordinate systems moving relative to each other at constant speeds.

It produced a new conception of space that would lay the groundwork for Einstein's theory of general relativity that would come later, and also established that as an object accelerates towards the speed of light, its mass also increases, which requires more energy to accelerate, which then adds even more mass to the object. As a result, as an object effectively approaches the speed of light, its mass becomes infinite, making the speed of light the effective speed limit for all matter.

His next paper that year, "Does the Inertia of a Body Depend upon its Energy Content?" was published in November 1905, and gave the mathematical proof of special relativity, confirming the equivalence of mass and energy, and introducing arguably the most famous equation in human history, E = mc2.

Finally, in 1907, Einstein published "Planck's Theory of Radiation and the Theory of Specific Heat", which was a foundational work of quantum mechanics.

While Einstein's Theory of Special Relativity was revolutionary in its own right, between 1909 and 1916, Einstein worked on a more general form of this theory that would be published in March 1916 as, "The Foundation of the General Theory of Relativity".

This paper was absolutely transformative. While Einstein's work on Special Relativity required an advanced understanding of math and physics, his theory of general relativity was much more accessible, owing to its elegance and (relative) simplicity.

Einstein envisioned gravity not as a force the way Newton described it but describing space and time as a fabric stretching out in all directions. If that space is empty, an object moving through it would travel in a straight line. But if that space has a massive object in the center, like the Sun, then the fabric of space warps toward that center of mass, turning the flat fabric of space into a kind of funnel.

An object passing through that space is affected by the shape of that funnel so that it no longer travels in straight lines through that space but instead gets pulled toward the mass in the center, effectively rolling down the slope of space towards the mass in the center.

Critically, if the speed of something passing through that space is great enough, like light, then it is not pulled into the center mass entirely, but its course is instead refracted as a consequence of the gravitational effect of that massive object.

It was this aspect of Einstein's theory that would help cement his reputation. Convinced that this deflection of light from distant stars could be seen in the gravitational field produced by the sun during a solar eclipse, Einstein sought but failed to verify his theory personally. In 1919, however, English astronomer Arthur Eddington and French astronomer Andrew Crommelin observed the deflection of light at two separate locations during the May 29 eclipse that year.

Confirmation of Einstein's prediction was announced on November 6, 1919, during a meeting in London of the Royal Society and Royal Astronomical Society. Joseph John Thompson, the Royal Society's president, declared that "This is the most important result related to the theory of gravitation since the days of Newton...This result is among the greatest achievements of human thinking."

Confirmation of Einstein's theory of gravitation was printed on the front page of newspapers around the world, establishing him forevermore in the public consciousness as the greatest scientific mind since Isaac Newton, and possibly even greater.

While Einstein was working out his theory of general relativity, he had already established himself in 1905 as a brilliant scientist. He still had trouble landing an academic position for himself, though, being rejected by the University of Bern in 1907 for a professorial position. He was successful on his second go-around a year later, however, and landed a position in 1908, giving his first lecture as a professor at the end of that year.

Devoting himself to his scientific endeavors, he gave up his post with the patent office in 1909 and bounced around between Bern, Zurich, and Prague until 1914, when Planck and German chemist Walther Nernst convinced Einstein to take up a post in Berlin, then the world's epicenter for natural science research.

They offered him a non-teaching professorship at Berlin University, made him a member of the Prussian Academy of Sciences, and made him the head of the yet-to-be-founded Kaiser Wilhelm Insitute of Physics.

Einstein's global popularity led to invitations to speak from around the world, offers Einstein took up, traveling to the United States, France, Britain, Palestine, and elsewhere.

Einstein traveled to Asia as well, and contrary to his public image as a great humanitarian who decried racism as "a disease of white people," his travel diaries from that timeexpressed somesweeping and negative generalizationsof the people he met in Asia, especially the Chinese.

People are a study in contradictions, and Einstein could both believe that racism was social cancer while holding some particularly abhorrent views himself. And while many of his recently published personal papers were written in the early 1920s, when such opinions would not have been seen as particularly out of the mainstream, this certainly does not absolve him - although he also clearly changed over time.

This is especially true as he himself was the subject of some especially ugly anti-Semitic attacks from those inside the scientific community and among the broader public. There were those in Germany, including Nobel laureates like Johannes Stark and Philipp Lenard, who advocated for a "German physics" separate from "Jewish physics".

In December 1932, Einstein and his wife Elsa left for the United States for a series of lectures just as the Nazi Party was on the rise, having secured the most seats in the German parliament elections held earlier that year. In January 1933, Adolf Hitler seized power and in response, Einstein cut all ties with any scientific and academic institution in Germany that he had, including resigning from the Prussian Academy of Sciences. He would never again return to Germany.

Now more or less a refugee, Einstein was quickly given a position at the Institute for Advanced Studies in Princeton, NJ. He bought a house there, the famous 112 Mercer Street.

In 1940, Einstein was formally granted US citizenship and renounced his German citizenship for the second time though he retained his Swiss citizenship. He would live the rest of his life in the United States.

Einstein was a committed pacifist, but his horror at the thought of Nazi Germany working on atomic weapons compelled him to sign a letter to then-President Franklin D. Roosevelt that raised the alarm, recommending that the United States begin researching atomic weaponry as well.

Though this would be Einstein's only direct involvement in the Manhattan Project, giving hisimprimatur to the effort certainly helped make the case for the project, and his famous equation equating mass and energy was fundamental to the project's development.

Einstein spent the rest of his life pursuing aunified field theorybut was unable to make any breakthroughs in this area. His contemporaries had become enamored with some of what he regarded as the stranger aspects of quantum mechanics, which Einstein criticized.

Rejecting the use of probability and randomness in describing quantum effects, Einstein famously declared that, "[God] does not play dice with the universe."

This disagreement and his failure to make major progress in his work on unified field theory led to his isolation from the scientific community in his later years, though Einstein did not appear to be bitter about this fact.

On April 15, 1955, Albert Einstein suffered debilitating pain and was rushed to a hospital in Princeton. He was diagnosed with an aneurysm in his abdominal aorta, and doctors were unable to save him.

Einstein died on April 18, 1955. In accordance with his will, he was cremated that day and his ashes spread at an unknown location. Though his later career proved to be mostly fruitless, he exerted a substantial gravity of his own on those around him, even helping the likes of Niels Bohr refine the principles of quantum mechanics by virtue of his critiques of it.

Einstein's work redefined the universe as we know it and gave us the clearest, most elegant model to date to help even the layman understand it. The foundation he laid for theoretical physics has led to the discovery of gravitational lensing and the greatest cosmological monsters of all, black holes.

Albert Einstein, like Isaac Newton and other great minds before him, surely stood on the shoulders of the giants who came before them, but few giants have ever stood as tall as Einstein and it may be centuries before we see so revolutionary a scientific figure.

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Albert Einstein: The Life and Legacy of the Great Genius Albert Einstein was one of the - Interesting Engineering

With the passing last month of Steven Weinberg, the world lost a great theoretical physicist. Born to Jewish parents in New York in 1933, Weinberg received the Nobel Prize in 1979 for unifying two of the four fundamental forces of physics, the electromagnetic and weak nuclear forces. His proposed unification, later confirmed by experiment, proved key to the development of the Standard Model of particle physics, the best current theory of fundamental physics and our guide to the strange world of elementary particles. In addition, Weinberg made seminal contributions to quantum theory, general relativity and cosmology.

His death also marks the twilight of an increasingly dated view of the relationship between science and religion. Though Weinberg was a friend to the State of Israel, he was not sympathetic to Judaism or any theistic belief. Weinberg wrote many popular books about physics in which he often asserted that scientific advance had undermined belief in God and, consequently, any ultimate meaning for human existence. The First Three Minutes, his most popular book published in 1977, famously concluded: the more the universe seems comprehensible, the more it seems pointless.

Weinbergs aggressive science-based atheism now seems an increasingly spent force. Since 1977, Carl Sagan, Richard Dawkins, Stephen Hawking, Victor Stenger, Lawrence Krauss and many other scientists have published popular anti-theistic broadsides. Many of these stalwarts have since passed from the scene. Others have so overplayed their hands with overt attacks on religion that they have provoked even fellow atheists and agnostics to recoil.

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Figures such as historian Tom Holland, social critic Douglas Murray, psychologist Jordan Peterson and social scientist Charles Murray now openly lament the loss of a religious mooring in culture, though they personally find themselves unable to believe. These New New Atheists, as distinct from the Old New Atheists, do not regard sciences alleged support for unbelief as one of its great achievements, as Weinberg described it.

Nevertheless, many such religious skeptics have yet to recognize the most important reason to reject science-based atheistic polemics: The most relevant scientific discoveries of the last century simply do not support atheism or materialism. Instead, they point in a decidedly different direction.

In The First Three Minutes, Weinberg described in detail the conditions of the universe just after the Big Bang. But he never attempted to explain what caused the Big Bang itself.

Nor could he. If the physical universe of matter, energy, space and time had a beginning as observational astronomy and theoretical physics have increasing suggested it becomes extremely difficult to conceive of an adequate physical or materialistic cause for the origin of the universe. After all, it was matter and energy that first came into existence at the Big Bang. Before that, no matter or energy no physics would have yet existed that could have caused the universe to begin.

Such considerations have led other prominent scientists such as Israeli physicist Gerald Schroeder and the late Caltech astronomer Allan Sandage to affirm an external creator beyond space and time as the best explanation for the origin of the universe. The logic of this view made Weinberg initially reluctant to accept the Big Bang and inclined him, instead, to favor the rival steady state theory. As he explained before coming around, the steady state is philosophically the most attractive theory because it least resembles the account given in Genesis.

Fellow Nobel laureate and physicist Arno Penzias whose discovery of the cosmic background radiation helped kindle Weinbergs interest in Big Bang cosmology noted the obvious connection between the Big Bang and the concept of divine creation. As he argued, the best data we have are exactly what I would have predicted had I nothing to go on but the first five books of Moses, the Psalms and the Bible as a whole.

Weinberg also brilliantly used anthropic reasoning to estimate the value of the cosmological constant the outward pushing, anti-gravity force responsible for the expansion of the universe from its singular beginning. He showed that if we assume the universe needed to produce life, then the cosmological constant had to fall within a narrow, highly improbable and otherwise unexpected range as has proven to be the case.

To explain such extreme fine tuning without recourse to a transcendent fine-tuner, Weinberg favored the postulation of a multiplicity of other universes, an idea he acknowledged as speculative. The multiverse concept portrays our universe as the outcome of a grand lottery in which some universe-generating mechanism spits out trillions and trillions of universes so many that our universe with its improbable combination of life-conducive factors would eventually have to arise.

Yet, multiverse advocates overlook an obvious problem. All such proposals posit universe generating mechanisms that themselves require prior unexplained fine-tuning thus, taking us back to the need for an ultimate fine-tuner.

On his passing, Scientific Americans tribute to Weinberg described how scientifically literate people need to learn to live in Steven Weinbergs pointless universe. Yet Weinbergs own research built upon, or helped to make, two key scientific discoveries the universe had a beginning and has been finely-tuned from the beginning that do not imply a purposeless cosmos. Arguably, they point, instead, to a purposeful creator behind it all.

The writer is director of Discovery Institutes Center for Science & Culture and the author most recently of Return of the God Hypothesis: Three Scientific Discoveries That Reveal the Mind Behind the Universe.

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Steven Weinberg and the twilight of the godless universe - The Jerusalem Post

Department of Physics

Grade 7: - 33,797 to 35,845 per annumFixed Term - Full TimeContract Duration: 36 monthContracted Hours per Week: 35Closing Date: 27-Aug-2021, 6:59:00 AM

Durham University

Durham University is one of the world's top universities with strengths across the Arts and Humanities, Sciences and Social Sciences. We are home to some of the most talented scholars and researchers from around the world who are tackling global issues and making a difference to people's lives.

The University sits in a beautiful historic city where it shares ownership of a UNESCO World Heritage Site with Durham Cathedral, the greatest Romanesque building in Western Europe. A collegiate University, Durham recruits outstanding students from across the world and offers an unmatched wider student experience.

Less than 3 hours north of London, and an hour and a half south of Edinburgh, County Durham is a region steeped in history and natural beauty. The Durham Dales, including the North Pennines Area of Outstanding Natural Beauty, are home to breathtaking scenery and attractions. Durham offers an excellent choice of city, suburban and rural residential locations. The University provides a range of benefits including pension and childcare benefits and the Universitys Relocation Manager can assist with potential schooling requirements.

Durham University seeks to promote and maintain an inclusive and supportive environment for work and study that assists all members of our University community to reach their full potential. Diversity brings strength and we welcome applications from across the international, national and regional communities that we work with and serve.

The Department

The Department of Physics at Durham University is one of the leading UK Physics departments with an outstanding reputation for excellence in teaching, research, and employability.

The Department is committed to advancing equality and we aim to ensure that our culture is inclusive, and that our systems support flexible and family-friendly working, as recognized by our Juno Champion and Athena SWAN Silver awards.

We recognise and value the benefits of diversity throughout our staff and students.

The Role

A Postdoctoral Research Associate position is available to pursue experimental research in the field of atomic and laser physics within the Durham Atomic and Molecular Physics group. The position is associated with an existing experiment funded by the UK Engineering and Physical Science Research Council (EPSRC) focused on Quantum Optics using Rydberg atoms.

The post holder will be expected to display the initiative and creativity, together with the appropriate skills and knowledge, required to lead and develop the existing experiment to meet the project goals. The post holder will be expected to be familiar with the ultra-stable lasers, and have experience in atomic physics, quantum optics or laser cooling and trapping. The post holder is expected to be able to work effectively both independently and as part of a small research team. It is expected that the post holder will enhance the international contacts of the group through the presentation of work at international conferences. The post holder will also be expected to aid in the supervision of graduate students within the group as well as contributing to the undergraduate teaching within the Department.

The goal of the Rydberg project is to realise strong photon interactions with a high fidelity (preservation of properties of the incoming photons). The successful candidate will be required to take a lead role in all aspects of their project, contributing directly to the experiment and working closely with Prof Charles Adams, Prof Kevin Weatherill, project partners, and graduate students as well as other members of the research group and will be expected to undertake an active role in the laboratory activity

The Department of Physics is committed to building and maintaining a diverse and inclusive environment. It is pledged to the Athena SWAN charter, where we hold a silver award, and has the status of IoP Juno Champion. We embrace equality and particularly welcome applications from women, black and minority ethnic candidates, and members of other groups that are under-represented in physics. Durham University provides a range of benefits including pension, flexible and/or part time working hours, shared parental leave policy and childcare provision.

Responsibilities

The post is for a fixed term of 36 months as it is associated with an existing experiment with fixed-term funding from the UK Engineering and Physical Science Researcher Council (EPSRC) focused on Quantum Optics using Ryberg atoms.

The post-holder is employed to work on research/a research project which will be led by another colleague. Whilst this means that the post-holder will not be carrying out independent research in his/her own right, the expectation is that they will contribute to the advancement of the project, through the development of their own research ideas/adaptation and development of research protocols.

Successful applicants will ideally be in post by 1st October 2021.

How to Apply

For informal enquiries please contact Kevin Weatherill (K.j.weatherill@durham.ac.uk).All enquiries will be treated in the strictest confidence.

The Joint Quantum Centre (JQC) is one of the UKs leading centres for atomic, molecular and optical physics research. Members of the JQC span the Physics and Chemistry Departments at Durham University and the Applied Mathematics Department at Newcastle University. Projects within the JQC investigate experimental and theoretical topics ranging from laser cooling and Bose-Einstein Condensation to nonlinear optics and Rydberg physics. The atomic and molecular physics group in the Department of Physics comprises 10 faculty, 11 post-doctoral researchers and 22 Ph.D. students. Further details of the research activities of the group can be found athttp://www.jqc.org.uk/

We prefer to receive applications online via the Durham University Vacancies Site.https://www.dur.ac.uk/jobs/. As part of the application process, you should provide details of 3 (preferably academic/research) referees and the details of your current line manager so that we may seek an employment reference.

Applications are particularly welcome from women and black and minority ethnic candidates, who are under-represented in academic posts in theUniversity.

What to Submit

All applicants are asked to submit:

Next Steps

Shortlisted candidates will be invited for interview and assessments.

The Requirements

Essential Criteria:

Desirable Criteria:

DBS Requirement:Not Applicable.

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Postdoctoral Research Associate in Quantum Light and Matter job with DURHAM UNIVERSITY | 262887 - Times Higher Education (THE)

An artists impression of Tcc+, a tetraquark composed of two charm quarks and an up and a down antiquark. Credit: CERN

Discovery of a new exotic hadron containing two charm quarks and an up and a down antiquark.

Recently, the Large Hadron Collider beauty (LHCb) experiment at CERN presented a new discovery at the European Physical Society Conference on High Energy Physics (EPS-HEP). The new particle discovered by LHCb, labeled as Tcc+, is a tetraquark an exotic hadron containing two quarks and two antiquarks. It is the longest-lived exotic matter particle ever discovered, and the first to contain two heavy quarks and two light antiquarks.

Quarks are the fundamental building blocks from which matter is constructed. They combine to form hadrons, namely baryons, such as the proton and the neutron, which consist of three quarks, and mesons, which are formed as quark-antiquark pairs. In recent years a number of so-called exotic hadrons particles with four or five quarks, instead of the conventional two or three have been found. Todays discovery is of a particularly unique exotic hadron, an exotic exotic hadron if you like.

The new particle contains two charm quarks and an up and a down antiquark. Several tetraquarks have been discovered in recent years (including one with two charm quarks and two charm antiquarks), but this is the first one that contains two charm quarks, without charm antiquarks to balance them. Physicists call this open charm (in this case, double open charm). Particles containing a charm quark and a charm antiquark have hidden charm the charm quantum number for the whole particle adds up to zero, just like a positive and a negative electrical charge would do. Here the charm quantum number adds up to two, so it has twice the charm!

The quark content of Tcc+ has other interesting features besides being open charm. It is the first particle to be found that belongs to a class of tetraquarks with two heavy quarks and two light antiquarks. Such particles decay by transforming into a pair of mesons, each formed by one of the heavy quarks and one of the light antiquarks. According to some theoretical predictions, the mass of tetraquarks of this type should be very close to the sum of masses of the two mesons. Such proximity in mass makes the decay difficult, resulting in a longer lifetime of the particle, and indeed Tcc+ is the longest-lived exotic hadron found to date.

The discovery paves the way for a search for heavier particles of the same type, with one or two charm quarks replaced by bottom quarks. The particle with two bottom quarks is especially interesting: according to calculations, its mass should be smaller than the sum of the masses of any pair of B mesons. This would make the decay not only unlikely, but actually forbidden: the particle would not be able to decay via the strong interaction and would have to do so via the weak interaction instead, which would make its lifetime several orders of magnitude longer than any previously observed exotic hadron.

The new Tcc+ tetraquark is an enticing target for further study. The particles that it decays into are all comparatively easy to detect and, in combination with the small amount of the available energy in the decay, this leads to an excellent precision on its mass and allows the study of the quantum numbers of this fascinating particle. This, in turn, can provide a stringent test for existing theoretical models and could even potentially allow previously unreachable effects to be probed.

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Twice the Charm: Long-Lived Exotic Particle Discovered at Large Hadron Collider - SciTechDaily