Researchers have demonstrated a new form of light, called "rotatum," which carries transverse angular momentum along the propagation direction. Unlike circularly polarized light, where the electric and magnetic fields rotate transverse to the propagation direction, in rotatum, these fields rotate along the direction of travel, tracing a spiral trajectory. This unique property arises from a specific superposition of two vortex beams with opposite orbital angular momentum and opposite circular polarization. Experimental generation and characterization of rotatum using vectorially structured light confirms its theoretical predictions, opening new avenues for optical manipulation, quantum information, and high-dimensional light–matter interactions.
Purple has no dedicated wavelength of light like red or green. Our brains create the perception of purple when our eyes simultaneously detect red and blue light wavelengths. This makes purple a "non-spectral" color, a product of our visual system's interpretation rather than a distinct physical property of light itself. Essentially, purple is a neurological construct, a color our brains invent to bridge the gap between red and blue in the visible spectrum.
Hacker News users discuss the philosophical implications of purple not being a spectral color, meaning it doesn't have its own wavelength of light. Several commenters point out that all color exists only in our brains, as it's our perception of different wavelengths, not an inherent property of light itself. The discussion touches on the nature of qualia and how our subjective experience of color differs, even if we agree on labels. Some debate the technicalities of color perception, explaining how our brains create purple by interpreting the simultaneous stimulation of red and blue cone cells. A few comments also mention the arbitrary nature of color categorization across languages and cultures.
Danish painter Vilhelm Hammershøi (1864-1916) mastered a distinctive style characterized by muted greys, quiet interiors, and a pervasive sense of stillness and solitude. He often depicted the sparsely furnished rooms of his Copenhagen apartments, focusing on architectural details and the play of light and shadow. While figures occasionally appear, often with their backs turned or faces obscured, they primarily serve to enhance the atmosphere of introspective contemplation and mystery that permeates his work. Hammershøi's paintings evoke a sense of timelessness and invite viewers to reflect on the beauty found in simplicity and the enigmatic nature of everyday life.
Hacker News users discuss Hammershøi's evocative use of light and shadow, with several noting the profound sense of stillness and quietude his paintings create. Some commenters draw parallels between his work and the photography of Gregory Crewdson, citing similar themes of introspection and isolation. Others praise the article's writing style and the author's clear passion for the subject. The artist's limited color palette also sparks discussion, with some speculating on its psychological impact and others simply appreciating its aesthetic beauty. A few users mention the challenges of accurately representing Hammershøi's subtle greys in digital reproductions.
Deep in the ocean, where sunlight barely penetrates, life thrives. This article explores how organisms in these light-starved environments survive. It focuses on rhodopsins, light-sensitive proteins used by microbes for energy production and signaling. Scientists have discovered rhodopsins remarkably tuned to the faint blue light that reaches these depths, maximizing energy capture. Further research has revealed the surprising diversity and adaptability of rhodopsins, showing they can even utilize thermal energy when light is completely absent. This challenges our understanding of life's limits and suggests that rhodopsin-based life could exist in even more extreme environments, including other planets.
Hacker News users discussed the surprising adaptability of life to extremely low-light environments, as described in the Quanta article. Several commenters highlighted the efficiency of biological systems in capturing and utilizing even the smallest amounts of available photons. Some discussed the implications for finding life in other environments, like the subsurface oceans of icy moons, and the possibility of life using alternative energy sources besides light. Others delved into the specific biochemical mechanisms mentioned in the article, like the role of rhodopsins and the challenges of studying these organisms. A few questioned the "barely any light" framing, pointing out that even seemingly dark environments like the deep ocean still have some bioluminescence and faint light penetration. One commenter also mentioned the possibility of life existing solely on chemical energy, independent of light altogether.
Lightcell has developed a novel thermophotovoltaic (TPV) generator that uses concentrated sunlight to heat a specialized material to high temperatures. This material then emits specific wavelengths of light efficiently absorbed by photovoltaic cells, generating electricity. The system aims to offer higher solar-to-electricity conversion efficiency than traditional photovoltaics and to provide energy storage capabilities by utilizing the heat generated within the system. This technology is geared towards providing reliable, clean energy, particularly for grid-scale power generation.
Hacker News users express significant skepticism regarding Lightcell's claims of a revolutionary light-based engine. Several commenters point to the lack of verifiable data and independent testing, highlighting the absence of peer-reviewed publications and the reliance on marketing materials. The seemingly outlandish efficiency claims and vague explanations of the underlying physics fuel suspicion, with comparisons drawn to past "too-good-to-be-true" energy technologies. Some users call for more transparency and rigorous scientific scrutiny before accepting the company's assertions. The overall sentiment leans heavily towards disbelief, pending further evidence.
The blog post "Das Blinkenlights" details the author's project to recreate the iconic blinking LED display atop the Haus des Lehrers building in Berlin, a symbol of the former East Germany. Using readily available components like an Arduino, LEDs, and a custom-built replica of the original metal frame, the author successfully built a miniature version of the display. The project involved meticulously mapping the light patterns, programming the Arduino to replicate the sequences, and overcoming technical challenges related to power consumption and brightness. The end result was a faithful, albeit smaller-scale, homage to a piece of history, demonstrating the blend of nostalgia and maker culture.
Hacker News users discussed the practicality and appeal of "blinkenlights," large-scale status displays using LEDs. Some found them aesthetically pleasing, nostalgic, and a fun way to visualize complex systems, while others questioned their actual usefulness, suggesting they often display superficial information or become mere decorations. A few comments pointed out the potential for misuse, creating distractions or even security risks by revealing system internals. The maintainability of such displays over time was also questioned. Several users shared examples of interesting blinkenlight implementations, including artistic displays and historical uses. The general consensus seemed to be that while not always practically useful, blinkenlights hold a certain charm and can be valuable in specific contexts.
Summary of Comments ( 1 )
https://news.ycombinator.com/item?id=43666083
Several Hacker News commenters discuss the "Rotatum of Light" study, questioning its novelty and practical implications. Some argue the observed effect is simply circular polarization, a well-established concept, and that the "rotatum" terminology is unnecessary jargon. Others express confusion about the potential applications, wondering if it offers any advantages over existing polarization techniques. A few users attempt to clarify the research, suggesting it explores a specific type of structured light with potential uses in optical trapping, communication, and quantum computing, though these uses remain speculative. The overall sentiment seems skeptical, with many questioning the significance of the findings and the hype surrounding them.
The Hacker News post titled "Rotatum of Light" with the ID 43666083 has a moderate number of comments discussing the linked Science Advances article about a newly described fundamental property of light called "rotatum." Many of the comments focus on understanding the implications and applications of this discovery.
Several commenters express excitement and wonder at the discovery of a new fundamental property of light, something considered rare in modern physics. They discuss the potential for this to open up new avenues of research and technological advancements. Some compare it to the discovery of spin angular momentum, highlighting the potential parallels and impact.
A significant portion of the discussion revolves around clarifying the difference between rotatum and existing properties of light like angular momentum and polarization. Commenters try to grasp the unique characteristics of rotatum and how it manifests in different scenarios, such as tightly focused light beams. Some raise questions about the experimental setup and the interpretation of the results presented in the article, seeking further clarification on the methodology used to isolate and measure rotatum.
The potential applications of rotatum are a topic of much speculation. Some commenters suggest potential uses in optical communications, particularly in increasing bandwidth or creating new modulation schemes. Others propose applications in areas like microscopy and optical manipulation of particles. However, many acknowledge that it's too early to predict concrete applications, with further research being necessary to explore the practical implications fully.
A few commenters also delve into the more technical aspects of the paper, discussing concepts like the symmetry properties of light fields and the mathematical framework used to describe rotatum. They engage in a more detailed examination of the underlying physics and the theoretical implications of the discovery.
There's a noticeable thread of discussion around the visualization and intuitive understanding of rotatum. Commenters grapple with the challenge of picturing this abstract property and try to relate it to more familiar concepts. Some propose analogies and visualizations to help grasp the nature of rotatum.
Finally, some comments express caution and skepticism, suggesting the need for further independent verification and research to solidify the findings and explore potential artifacts. They highlight the importance of rigorous scrutiny in scientific discoveries, particularly those claiming fundamental advancements.