A new study suggests the universe could decay far sooner than previously estimated, in approximately 10⁷⁸ years, due to the hypothetical decay of the Higgs boson vacuum. This timeline, while still astronomically long, is significantly shorter than prior estimates focusing on proton decay. The research highlights the instability of the current vacuum state, proposing it could transition to a lower energy state, potentially leading to a bubble of "true vacuum" expanding at the speed of light and obliterating everything in its path. However, this remains theoretical and depends on confirming current assumptions about particle physics and cosmology, including the mass of the top quark and the Higgs boson.
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.
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.
David Tong's webpage provides a collection of freely available lecture notes covering various topics in theoretical physics, aimed primarily at advanced undergraduate and beginning graduate students. The subjects range from classical mechanics and electromagnetism to quantum field theory, general relativity, string theory, and solitons, each offering a comprehensive and pedagogical approach. The notes are based on lectures Tong has delivered at the University of Cambridge and are continually updated. They include problem sets, further reading suggestions, and, in some cases, accompanying video lectures.
Hacker News users generally praised David Tong's lecture notes for their clarity, comprehensiveness, and accessibility. Several commenters highlighted the notes as an excellent resource for both students and those seeking to refresh their knowledge of physics. Some pointed out specific strengths, such as the clear explanations of challenging concepts like quantum field theory and general relativity. A few users mentioned minor typos or areas for improvement, but the overall sentiment was overwhelmingly positive, with many thanking Tong for making these resources freely available. Several commenters also discussed their own experiences using the notes, either as students or for self-study, further reinforcing their value.
Physicists are exploring the possibility of "paraparticles," a hypothetical third kingdom of quantum particles distinct from bosons and fermions. While bosons and fermions obey specific rules regarding how multiple identical particles occupy the same state, paraparticles would adhere to different, more exotic statistical rules. Though their existence hasn't been confirmed, researchers have developed mathematical frameworks describing their potential behavior and are investigating how to experimentally detect these elusive particles. If found, paraparticles could revolutionize our understanding of quantum mechanics and potentially have applications in quantum computing and other advanced technologies.
Several Hacker News commenters express skepticism about the practical implications of paraparticles, questioning whether they represent a genuinely new "kingdom" or simply a theoretical construct with limited experimental relevance. Some highlight the difficulty in distinguishing paraparticles from existing particle types due to their complex interactions, suggesting the distinction might be more mathematical than physical. Others note the article's lack of clarity on the potential applications or observable consequences of these particles, making it hard to assess their significance. A few commenters delve into the technical details, discussing the differences between anyons and paraparticles, and the challenges of observing these exotic behaviors in real-world systems. Overall, the comments lean towards cautious curiosity rather than outright excitement, emphasizing the need for further research to understand the true nature and importance of paraparticles.
CERN has released a conceptual design report detailing the feasibility of the Future Circular Collider (FCC), a proposed successor to the Large Hadron Collider. The FCC would be a much larger and more powerful collider, with a circumference of 91-100 kilometers, capable of reaching collision energies of 100 TeV. The report outlines the technical challenges and potential scientific breakthroughs associated with such a project, which would significantly expand our understanding of fundamental physics, including the Higgs boson, dark matter, and the early universe. The ambitious project is estimated to cost around €24 billion and would involve several phases, starting with an electron-positron collider followed by a proton-proton collider in the same tunnel. The report serves as a roadmap for future discussions and decisions about the next generation of particle physics research.
HN commenters discuss the immense cost and potential scientific return of the proposed Future Circular Collider (FCC). Some express skepticism about the project's justification, given its price tag and the lack of guaranteed breakthroughs. Others argue that fundamental research is crucial for long-term progress and that the FCC could revolutionize our understanding of the universe. Several comments compare the FCC to the SSC, a similar project canceled in the US, highlighting the political and economic challenges involved. The potential for technological spin-offs and the inspirational value of such ambitious projects are also mentioned. A few commenters question the timing, suggesting that resources might be better spent on more immediate global issues like climate change.
The CERN article is a humorous April Fool's Day piece. It satirically reports the "discovery" of quantum entanglement between sheep, attributing their flocking behavior to this quantum phenomenon. The article uses pseudo-scientific jargon and fabricated quotes to maintain the joke, while subtly referencing real physics concepts like Bell's inequality and quantum superposition. Ultimately, the article's purpose is lighthearted entertainment, not a genuine scientific announcement.
Hacker News users expressed significant skepticism about the linked article claiming quantum entanglement in sheep. Several commenters pointed out that the study measured correlations in sheep physiology, which could easily be explained by classical physics, like shared environmental factors. They argued that the article misrepresents or misunderstands the concept of quantum entanglement, and there's no evidence presented to suggest anything beyond classical correlations. Some users criticized the sensationalist headline and the poor quality of science reporting in general. A few commenters questioned the journal's credibility and the peer review process. Overall, the consensus was that the claim of quantum entanglement in sheep is unsubstantiated.
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.
The blog post explores the exceptional Jordan algebra, a 27-dimensional non-associative algebra denoted 𝔥₃(𝕆), built from 3x3 Hermitian matrices with octonion entries. It highlights the unique and intricate structure of this algebra, focusing on the Freudenthal product, a key operation related to the determinant. The post then connects 𝔥₃(𝕆) to exceptional Lie groups, particularly F₄, the automorphism group of the algebra, demonstrating how transformations preserving the algebra's structure generate this group. Finally, it touches upon the connection to E₆, a larger exceptional Lie group related to the algebra's derivations and the structure of its projective space. The post aims to provide an accessible, though necessarily incomplete, introduction to this complex mathematical object and its significance in Lie theory.
The Hacker News comments discuss the accessibility of the blog post about the exceptional Jordan algebra, with several users praising its clarity and the author's ability to explain complex mathematics in an understandable way, even for those without advanced mathematical backgrounds. Some commenters delve into the specific mathematical concepts, including octonions, sedenions, and their connection to quantum mechanics and string theory. One commenter highlights the historical context of the algebra's discovery and its surprising connection to projective geometry. Others express general appreciation for the beauty and elegance of the mathematics involved and the author's skill in exposition. A few commenters mention the author's other work and express interest in exploring further.
The question of whether a particle goes through both slits in the double-slit experiment is a misleading one, rooted in classical thinking. Quantum objects like electrons don't have definite paths like marbles. Instead, their behavior is described by a wave function, which evolves according to the Schrödinger equation and spreads through both slits. It's the wave function, not the particle itself, that interferes, creating the characteristic interference pattern. When measured, the wave function "collapses," and the particle is found at a specific location, but it's not meaningful to say which slit it "went through" before that measurement. The particle's position becomes definite only upon interaction, and retroactively assigning a classical trajectory is a misinterpretation of quantum mechanics.
Hacker News users discussed the nature of wave-particle duality and the interpretation of quantum mechanics in the double-slit experiment. Some commenters emphasized that the wave function is a mathematical tool to describe probabilities, not a physical entity, and that the question of "which slit" is meaningless in the quantum realm. Others pointed to the role of the measurement apparatus in collapsing the wave function and highlighted the difference between the wave function of the particle and the electromagnetic field wave. A few mentioned alternative interpretations like pilot-wave theory and many-worlds interpretation. Some users expressed frustration with the ongoing ambiguity surrounding quantum phenomena, while others found the topic fascinating and appreciated Strassler's explanation. A few considered the article too simplistic or misleading.
The paper explores the theoretical biological effects of a primordial black hole (PBH) with a tiny mass (around 10^15 grams) passing through a human body. While such an event is improbable, the authors calculate the gravitational forces exerted by the PBH as it traverses different tissues. They find that these forces, though exceeding Earth's gravity by many orders of magnitude for a brief period, are unlikely to cause significant macroscopic damage due to the extremely short interaction time. However, the study suggests potential disruptions at the cellular level, specifically stretching of DNA molecules, which might lead to mutations or other biological consequences. The overall conclusion is that while mechanically disruptive effects are likely minimal, biological impacts from the induced strains warrant further investigation.
Several Hacker News commenters expressed skepticism about the practicality of detecting the effects described in the paper, especially given the rarity of primordial black holes and the subtle nature of the gravitational influence. Some questioned the assumptions made in the calculations, like the density and velocity of the black holes. Others pointed out that other everyday gravitational forces, like those from nearby objects or even the moon, would likely dwarf the effect of a tiny black hole passing through the body. A few commenters engaged in humorous speculation about potential (and unlikely) biological impacts, while others debated the overall significance of the research. Several users also discussed the plausibility of primordial black holes as dark matter candidates.
Scientists have detected the highest-energy neutrino ever recorded, dubbed "Amaterasu," at the IceCube Neutrino Observatory in Antarctica. With an estimated energy of 2.6 PeV, it surpasses all previously observed neutrinos and provides valuable insight into extreme astrophysical events. While its origin remains uncertain, the neutrino's trajectory suggests a possible link to a tidal disruption event—the shredding of a star by a supermassive black hole—observed around the same time. This detection opens up new possibilities for understanding the most powerful phenomena in the universe.
Hacker News users discuss the implications of detecting such a high-energy neutrino, with some speculating about its origins (possibly a tidal disruption event or active galactic nucleus). Several commenters delve into the detection methods used by the IceCube Neutrino Observatory, highlighting the impressive feat of capturing such a rare event. Others debate the significance of the "record-breaking" nature of the neutrino, questioning the statistical certainty of its energy measurement and comparing it to previous detections like the "Big Bird" neutrino. There's also discussion about the challenges of neutrino astronomy, including the difficulty in pinpointing their source and the limitations of current detector technology. A few users express excitement about the potential of future neutrino detectors and the insights they may provide into the universe's most energetic phenomena.
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.
Summary of Comments ( 136 )
https://news.ycombinator.com/item?id=43961226
HN commenters discuss the vast timescale involved, questioning the meaning of such predictions so far into the future. Several express skepticism about the underlying physics and the ability to extrapolate current understanding to such extremes. Some point out the limitations of current models and the potential for unknown factors to influence the universe's ultimate fate. The practicality of worrying about an event so distant in the future is also questioned, with some suggesting focusing on more immediate concerns. A few commenters delve into the theoretical mechanisms of decay, including proton decay and vacuum metastability, but overall the discussion leans towards the philosophical implications of such a distant and uncertain event.
The Hacker News post titled "Universe expected to decay in 10⁷⁸ years, much sooner than previously thought" (linking to a Phys.org article about the potential decay of the universe) has generated several comments discussing the implications of this timescale and the underlying physics.
Several commenters express a sense of perspective about the vastness of 10⁷⁸ years, pointing out that it renders concerns about human timescales insignificant. One commenter humorously states it "gives me some comfort that we have time to fix climate change." Others delve into the limitations of making predictions so far into the future, highlighting the possibility of unknown physics changing the current understanding. One comment points out the challenges in extrapolating current models over such extreme durations, and the likelihood of unforeseen events or changes in fundamental constants. The speculative nature of the decay process itself is also discussed, with mentions of proton decay and the limitations of current knowledge in particle physics.
Another thread of discussion revolves around the interpretation of "decay" in this context. Commenters clarify that it doesn't mean the universe will disappear, but rather transition into a different, less structured state, potentially a "thin soup of radiation." There's some debate about the nature of this eventual state and whether it truly represents "decay" in the traditional sense.
A few comments delve into the specifics of the research mentioned in the article, such as the role of Grand Unified Theories and the hypothesized decay of protons. One commenter questions the relevance of considering proton decay given other potential universe-ending scenarios that might occur sooner.
Finally, some commenters offer philosophical reflections on the implications of a finite universe, even on such an immense timescale. The discussion touches on the nature of time, the insignificance of human existence in the cosmic scale, and the challenges of comprehending such vast durations.
Overall, the comments reflect a mix of awe at the vastness of the timescale, skepticism about the reliability of such far-future predictions, and a genuine curiosity about the fundamental physics governing the universe's ultimate fate. The discussion stays largely grounded in scientific principles while also acknowledging the philosophical implications of such concepts.