The ALICE experiment at CERN's Large Hadron Collider has observed the transformation of lead nuclei into gold. This doesn't involve alchemy, but rather a natural, albeit rare, radioactive decay process. When lead ions collide in the LHC, they can lose a proton, resulting in an isotope of gold. This gold nucleus is unstable and quickly decays further, but its brief existence has been confirmed by ALICE through precision measurements of the particle's momentum and mass-to-charge ratio. This observation provides valuable data for understanding the nuclear structure of heavy ions and the processes occurring during high-energy collisions.
New research from the LHCb experiment at CERN reveals a greater than anticipated difference in how often the charm meson decays into a kaon and either a pion or a muon pair, depending on whether an up or down quark is involved. This asymmetry, which signifies a violation of charge-parity (CP) symmetry, is four times larger than the Standard Model of particle physics predicts. While not yet statistically definitive enough to claim a discovery, this substantial deviation hints at potential new physics beyond the Standard Model, possibly involving unknown particles or forces influencing these decays. Further data analysis is crucial to confirm these findings and explore the implications for our understanding of fundamental interactions.
HN commenters discuss potential implications of the discovery that the up/down quark mass difference is larger than previously thought. Some express excitement about the potential to refine the Standard Model and gain a deeper understanding of fundamental physics. Others are skeptical, pointing out the preliminary nature of the findings and questioning the significance of a small shift in already-known asymmetry. Several commenters delve into the technical details of lattice QCD calculations and the challenges involved in precisely determining quark masses. There's also discussion of the relationship between quark masses and the strong CP problem, with some suggesting this discovery might offer new avenues for exploration in that area.
Hans Bethe, renowned for calculating stellar energy production, surprisingly found success by applying simplifying assumptions to complex quantum problems. He tackled seemingly intractable calculations, like the splitting of energy levels in magnetic fields (Zeeman effect) and the behavior of crystals, by focusing on the most dominant interactions and ignoring smaller effects. This approach, though approximate, often yielded surprisingly accurate and insightful results, showcasing Bethe's knack for identifying the essential physics at play. His ability to "see through" complicated equations made him a pivotal figure in 20th-century physics, influencing generations of scientists.
Hacker News users discussed Bethe's pragmatic approach to physics, contrasting it with more mathematically driven physicists. Some highlighted his focus on getting usable results and his ability to simplify complex problems, exemplified by his work on the Lamb shift and stellar nucleosynthesis. Others commented on the article's portrayal of Bethe's personality, describing him as humble and approachable, even when dealing with complex subjects. Several commenters shared anecdotes about Bethe, emphasizing his teaching ability and the impact he had on their understanding of physics. The importance of approximation and "back-of-the-envelope" calculations in theoretical physics was also a recurring theme, with Bethe presented as a master of these techniques.
Scientists have measured the half-lives of superheavy elements moscovium, nihonium, and tennessine, providing crucial insights into the stability of these synthetic elements at the edge of the periodic table. Using a new detection system at the GSI Helmholtz Centre for Heavy Ion Research, they found slightly longer half-lives than previously estimated, bolstering theories about an "island of stability" where superheavy nuclei with longer lifespans could exist. These measurements contribute to a better understanding of nuclear structure and the forces governing these extreme atomic nuclei.
Hacker News users discussed the challenges and implications of synthesizing and studying superheavy elements. Some questioned the practical applications of such research, while others emphasized the fundamental importance of expanding our understanding of nuclear physics and the limits of matter. The difficulty in creating and detecting these elements, which exist for mere fractions of a second, was highlighted. Several commenters pointed out the fascinating implications of the "island of stability," a theoretical region where superheavy elements with longer half-lives might exist. One compelling comment noted the logarithmic scale used in the chart, emphasizing the dramatic differences in half-lives between elements. Another intriguing comment discussed the theoretical possibility of "magic numbers" of protons and neutrons leading to increased stability and the ongoing search for these elusive islands of stability. The conversation also touched on the limitations of current theoretical models and the need for further experimental work to refine our understanding of these exotic elements.
The article details the complex and delicate process of transporting the massive KATRIN experiment, designed to measure the mass of the neutrino, from various construction sites across Germany to its final destination at the Karlsruhe Institute of Technology. This involved meticulous planning and execution, including disassembling components, transporting them via barge and truck, and then reassembling the entire apparatus with incredible precision. The journey, spanning months and hundreds of kilometers, faced numerous logistical challenges, such as navigating narrow roads and rivers, and required constant monitoring to ensure the sensitive equipment remained undamaged. The successful completion of this logistical feat marked a major milestone in the quest to understand the fundamental properties of neutrinos.
HN commenters discuss the challenges and complexities of the KATRIN experiment, highlighting the incredible precision required to measure neutrino mass. Some express awe at the engineering feat, particularly the vacuum system and the size of the spectrometer. Others delve into the scientific implications of determining the neutrino mass, linking it to cosmological models and the nature of dark matter. There's skepticism about the feasibility of ever directly detecting a neutrino, given their weakly interacting nature, but also optimism about the potential for KATRIN and future experiments to refine our understanding of fundamental physics. Several commenters lament the lack of mainstream media coverage for such a significant scientific endeavor. A few offer technical insights into the experiment's design and the difficulties in eliminating background noise.
The weak nuclear force's short range is due to its force-carrying particles, the W and Z bosons, having large masses. Unlike the massless photon of electromagnetism which leads to an infinite-range force, the hefty W and Z bosons require significant energy to produce, a consequence of Einstein's E=mc². This large energy requirement severely limits the bosons' range, confining the weak force to subatomic distances. The Heisenberg uncertainty principle allows these massive particles to briefly exist as "virtual particles," but their high mass restricts their lifespan and therefore the distance they can travel before disappearing, making the weak force effectively short-range.
HN users discuss various aspects of the weak force's short range. Some highlight the explanatory power of the W and Z bosons having mass, contrasting it with the massless photon and long-range electromagnetic force. Others delve into the nuances of virtual particles and their role in mediating forces, clarifying that range isn't solely determined by particle mass but also by the interaction strength. The uncertainty principle and its relation to virtual particle lifetimes are also mentioned, along with the idea that "range" is a simplification for complex quantum interactions. A few commenters note the challenges in visualizing or intuitively grasping these concepts, and the importance of distinguishing between force-carrying particles and the fields themselves. Some users suggest alternative resources, including Feynman's lectures and a visualization of the weak force, for further exploration.
The article "A bestiary of exotic hadrons" explores the burgeoning field of exotic hadron discoveries. Beyond the conventional meson and baryon structures, physicists are increasingly finding particles with more complex quark configurations, such as tetraquarks and pentaquarks. These discoveries, facilitated by experiments like LHCb, are challenging existing quark models and prompting the development of new theoretical frameworks to explain these exotic particles' structures, properties, and their roles within the broader landscape of quantum chromodynamics. The article highlights specific examples of newly observed exotic hadrons and discusses the ongoing debates surrounding their interpretations, emphasizing the vibrant and evolving nature of hadron spectroscopy.
HN commenters generally express fascination with the complexity and strangeness of exotic hadrons. Some discuss the challenges in detecting and classifying these particles, highlighting the statistical nature of the process and the difficulty in distinguishing true signals from background noise. A few commenters dive deeper into the theoretical aspects, mentioning QCD, quark confinement, and the potential for future discoveries. Others draw parallels to other scientific fields like biology, marveling at the "zoo" of particles and the constant evolution of our understanding. Several express appreciation for the clear and accessible writing of the CERN Courier article, making the complex topic understandable to a wider audience. One commenter questions the practical applications of this research, prompting a discussion about the fundamental nature of scientific inquiry and its unpredictable long-term benefits.
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https://news.ycombinator.com/item?id=43937214
Several commenters on Hacker News expressed skepticism about the title's phrasing, clarifying that the process described in the article involves creating a very small amount of gold from lead for an extremely short period, and that it is not a viable method for producing gold. They point out that the energy cost far exceeds the value of the gold produced. Some discussed the nuclear physics involved, explaining the difference between nuclear fission and fusion, and how this experiment relates to neither. The impracticality of the process for gold production was a recurring theme. Others mentioned the difficulties of separating the gold from the lead target, further emphasizing the lack of practical application. A few comments jokingly referred to alchemy, contrasting the reality of the experiment with the historical pursuit of transmuting base metals into gold.
The Hacker News post titled "ALICE detects the conversion of lead into gold at the LHC" has generated several comments discussing the linked article about the ALICE experiment at CERN. The discussion mainly revolves around the practicality and efficiency of using this method for gold production, the nature of the nuclear reactions involved, and the historical context of alchemy.
Several commenters point out that the amount of gold produced in this experiment is incredibly tiny and the process is incredibly energy-intensive, making it completely impractical for actual gold production. They emphasize that the energy cost vastly outweighs the value of the minuscule amount of gold created. One commenter humorously calculates that the electricity bill for producing a noticeable quantity of gold this way would be astronomical.
Some comments delve into the specifics of the nuclear reaction. They explain that this isn't true "alchemy" in the traditional sense, as it doesn't involve transmuting lead into gold through chemical means. Instead, it's a nuclear physics process involving high-energy collisions that strip protons from lead nuclei, resulting in a small probability of creating gold isotopes. This process, they explain, is more akin to nuclear fission or fusion than the chemical transformations sought by alchemists.
A few comments highlight the historical context, mentioning the long-standing human fascination with transmuting base metals into gold and the historical pursuit of alchemy. They note the irony that while physicists can now technically achieve this transformation, it's completely impractical and serves no real purpose other than scientific understanding.
One commenter questions the phrasing of the title, suggesting it's misleading because it implies a large-scale conversion. They argue that the title should emphasize the minuscule amounts and the purely scientific nature of the observation.
There's a brief discussion on the potential applications of the research. While gold production is ruled out, some suggest that the understanding gained from studying these high-energy nuclear reactions could have implications for other areas of nuclear physics or materials science. However, no specific applications are discussed in detail.
Finally, a few comments offer corrections or clarifications to previous comments, ensuring the scientific accuracy of the discussion. For example, one comment clarifies the specific isotopes of lead and gold involved in the reaction.