A proposed cosmic radio detector, outlined in a recent study, could potentially identify axion dark matter within the next 15 years. The detector would search for radio waves emitted when axions, a hypothetical dark matter particle, convert into photons in the magnetic fields of neutron stars. This new method leverages the strong magnetic fields around neutron stars to enhance the signal and improve the chances of detection, potentially providing a breakthrough in our understanding of dark matter. The approach focuses on a specific radio frequency band where the signal is expected to be strongest and distinguishes itself from other axion detection strategies.
The post explores the surprising discrepancy between the estimated and observed rates of supernovae. While theoretical models predict hundreds of billions of supernovae across the observable universe annually, current surveys only detect a small fraction of that. This vast difference isn't due to faulty models, but rather the difficulty in observing these explosions. Dust, intervening galaxies, and the sheer expanse of the universe obscure the majority of supernovae from our view, making their detection a challenging endeavor despite their immense power. This explains why, even with sophisticated telescopes, we only observe a relatively tiny number compared to the predicted cosmic abundance.
HN commenters generally expressed awe at the sheer scale of supernovae occurring in the observable universe, with some emphasizing the vastness of space this implies. Several pointed out that the article's title was misleading as it conflated observable universe numbers with those in our own galaxy, where supernovae are much rarer. One commenter highlighted the counterintuitive fact that distant supernovae, though individually fainter, are collectively brighter than those nearby due to the sheer number at those distances. There was also discussion about the accuracy of the estimates, the methodology used, and the different types of supernovae. Some users shared links to further resources and tools like a supernova simulator. A few commenters jokingly lamented the lack of easily visible supernovae from Earth.
You, having just died, meet God. God explains that everyone who has ever lived, is living, or will live is actually the same singular being – you. Every act of kindness and every act of cruelty you've ever experienced, you inflicted upon yourself. This is because all of existence is a single soul experiencing itself from every possible perspective, necessary to eventually mature and become God. Once you've lived every human life, you will merge with God, effectively becoming God. Your current life is just one of countless lives you will live as you progress toward this ultimate union.
HN users largely shared positive reactions to Andy Weir's "The Egg." Many commented on its thought-provoking nature and how it resonated with them personally, sparking reflections on empathy, interconnectedness, and the meaning of life. Some users discussed their interpretations of specific aspects, such as the concept of reincarnation and the cyclical nature of existence presented in the story. A few pointed out the similarity to the older parable of Brahma, while others discussed its impact on their worldview and how it encouraged kindness and understanding. There was some lighthearted debate about the logistics of the narrative's premise, but the overall sentiment was appreciation for its simple yet profound message.
Contrary to expectations of random distribution, a new study using James Webb Space Telescope data has found a surprising number of early galaxies exhibiting a preferred direction of rotation—clockwise, from Earth's perspective. This observed alignment, found across a large patch of sky and at a significant distance corresponding to a young universe, challenges current cosmological models which predict no large-scale rotational preference. While further investigation is needed to confirm this finding and understand its implications, it could suggest the early universe possessed a large-scale structure or influence that isn't currently accounted for in standard models.
Hacker News commenters largely discussed the misleading nature of the article's title and premise. Several pointed out that "clockwise" and "counter-clockwise" are observer-dependent terms and meaningless in the context of galaxies scattered throughout space. Others highlighted the actual finding of the study: that galaxy rotation directions appear correlated across vast distances, hinting at potential large-scale structures influencing galaxy formation, a finding much more nuanced than the simple "clockwise" assertion. Some users questioned the statistical significance of the findings, while others expressed excitement at the potential implications for cosmological models and our understanding of the universe's early moments. A few commenters also discussed the challenges of communicating complex scientific concepts accurately to the public.
NASA's SPHEREx mission, a near-infrared space telescope, is set to launch no earlier than June 2025. Its two-year mission will map the entire sky four times, creating a massive 3D map of hundreds of millions of galaxies and more than 100 million stars in the Milky Way. This data will help scientists study the early universe's expansion, the origin of water and other life-sustaining molecules, and the formation of galaxies.
Hacker News users generally expressed excitement about the SPHERX mission and its potential to expand our understanding of the universe. Several commenters discussed the implications of mapping such a vast number of galaxies for studying dark energy and cosmic inflation. Some questioned the $98M budget, wondering how it could be so low compared to other space telescopes. A few users highlighted the importance of near-infrared spectroscopy in SPHERX's mission, while others discussed the trade-offs between cost and scientific capabilities compared to larger telescopes. Technical details, like the use of a two-mirror, three-element unobscured anastigmat telescope, were also mentioned. There's a thread discussing the lack of detail in the NBC article and the need for more comprehensive reporting on scientific endeavors. Finally, some commenters expressed hope for discovering signs of extraterrestrial life or other unexpected phenomena.
The blog post "Open and Closed Universes" explores the concept of universe curvature and its implications for the universe's ultimate fate. It explains how a "closed" universe, with positive curvature like a sphere, would eventually collapse back on itself in a "Big Crunch," while an "open" universe, with negative curvature like a saddle, would expand indefinitely. A "flat" universe, with zero curvature, represents a critical point between these two scenarios, also expanding forever but at a decelerating rate. The post uses the analogy of a ball thrown upwards to illustrate these concepts, where the ball's trajectory depends on its initial velocity relative to escape velocity. It concludes by mentioning the current scientific consensus, based on observations, which favors a flat or very slightly open universe, destined for continuous expansion and eventual heat death.
HN commenters largely discuss the difficulty of truly comprehending the vastness and complexity of the universe, with some pointing out the limitations of human intuition and the challenges of visualizing higher dimensions. Several express fascination with the concept of a closed universe and its implications for the finite yet unbounded nature of space. Some debated the philosophical implications, touching upon the potential for simulated universes and questioning the nature of reality if our universe is indeed closed. A few comments also delve into more technical aspects, like the role of dark energy and the expansion of the universe in determining its ultimate fate. One commenter suggests looking at the problem through the lens of information theory and entropy, proposing that the universe might be both open and closed simultaneously depending on the observer's perspective.
Cosmologists are exploring a new method to determine the universe's shape – whether it's flat, spherical, or saddle-shaped – by analyzing pairings of gravitational lenses. Traditional methods rely on the cosmic microwave background, but this new technique uses the subtle distortions of light from distant galaxies bent around massive foreground objects. By examining the statistical correlations in the shapes and orientations of these lensed images, researchers can glean information about the curvature of spacetime, potentially providing an independent confirmation of the currently favored flat universe model, or revealing a surprising deviation. This method offers a potential advantage by probing a different cosmic epoch than the CMB, and could help resolve tensions between existing measurements.
HN commenters discuss the challenges of measuring the universe's shape, questioning the article's clarity on the new method using gravitational waves. Several express skepticism about definitively determining a "shape" at all, given our limited observational vantage point. Some debate the practical implications of a closed universe, with some suggesting it doesn't preclude infinite size. Others highlight the mind-boggling concept of a potentially finite yet unbounded universe, comparing it to the surface of a sphere. A few commenters point out potential issues with relying on specific models or assumptions about the early universe. The discussion also touches upon the limitations of our current understanding of cosmology and the constant evolution of scientific theories.
Summary of Comments ( 13 )
https://news.ycombinator.com/item?id=43715790
Several Hacker News commenters express skepticism about the feasibility of distinguishing dark matter signals from foreground noise, particularly given the immense challenge of shielding the detector from terrestrial and solar radio interference. Some highlight the long timeframe (15 years) mentioned in the article, questioning whether more immediate, albeit less ambitious, projects might yield more valuable data sooner. Others note the inherent difficulty of detecting something unknown, particularly when relying on speculative models of dark matter interaction. A few commenters point out the exciting potential of such a discovery, but temper their enthusiasm with the acknowledgement of the substantial technical and theoretical hurdles involved.
The Hacker News post titled "Cosmic radio' detector could discover dark matter within 15 years" linking to a Phys.org article about a new radio detector aimed at exploring the cosmic dark ages has generated several comments. Many of the commenters express excitement and interest in the potential for uncovering more information about dark matter and the early universe.
A recurring theme is the challenge of distinguishing the faint signal of dark matter from other cosmic noise. One commenter highlights the immense difficulty, comparing it to "trying to hear a whisper in a hurricane." This leads to a discussion about the sensitivity of the proposed detector and the advanced techniques required to filter out interference.
Several commenters delve into the technical details of the proposed detector, specifically mentioning the use of the 21-cm hydrogen line. They discuss how this specific wavelength is crucial for observing the early universe and potentially detecting dark matter interactions. One commenter points out the importance of shielding the detector from terrestrial radio frequency interference, suggesting that a location on the far side of the moon might be ideal. This sparks further conversation about the logistical and financial hurdles of such an undertaking.
There's also a thread discussing the nature of dark matter itself. Commenters explore different hypotheses, including axions and WIMPs, and speculate on how this new detector might contribute to our understanding of these elusive particles. One commenter expresses skepticism about finding dark matter within the proposed 15-year timeframe, emphasizing the complexity and uncertainty surrounding dark matter research.
Finally, some commenters draw parallels to other large-scale scientific projects like the James Webb Space Telescope, emphasizing the potential for groundbreaking discoveries and the importance of continued investment in fundamental research. Overall, the comments reflect a mixture of optimism, cautious anticipation, and technical curiosity about the potential of this new radio detector to shed light on some of the biggest mysteries in cosmology.