Sam Kean's "Caesar's Last Breath" explores the fascinating interconnectedness of the air we breathe through history and science. The book uses the premise that we likely inhale some of the same molecules Julius Caesar exhaled in his dying breath to delve into the composition of air, its elements, and their roles in various historical events. From the Big Bang to modern pollution, Kean examines the impact of atmospheric gases on everything from the Hindenburg disaster to climate change, weaving together scientific principles with engaging anecdotes and historical narratives. The book ultimately reveals the surprising stories contained within the seemingly simple act of breathing.
"Induced atmospheric vibration" refers to the phenomenon where seismic waves from earthquakes or underground explosions cause the ground to vibrate, which in turn pushes on the air above it, generating low-frequency sound waves (infrasound). These infrasound waves can travel long distances through the atmosphere and be detected by specialized sensors. While the term itself isn't standard scientific terminology, the process it describes is a recognized effect. These atmospheric pressure fluctuations are related to, but distinct from, the ground motion itself and can even be used to detect and characterize seismic events.
Hacker News users discussed the Stack Exchange question about "induced atmospheric vibration," largely focusing on whether the phenomenon is real or misinterpretation. Several commenters expressed skepticism, suggesting the perceived vibrations could be explained by more mundane phenomena like wind gusts, ground vibrations, or infrasound interacting with structures. One commenter pointed out the lack of credible scientific literature on the topic, reinforcing the idea that "induced atmospheric vibration" may not be a recognized scientific concept. Others debated the potential role of temperature gradients and air density fluctuations. A few commenters offered alternative explanations, such as the movement of large vehicles or industrial equipment causing vibrations that propagate through the ground and air. The overall sentiment suggests a healthy dose of skepticism toward the original question's premise.
Researchers from NTT and the University of Tokyo have successfully triggered and guided a lightning strike using a drone equipped with a grounded conducting wire. This marks the first time a drone has been used to intentionally direct a natural lightning discharge, offering a new method for lightning protection of critical infrastructure. The drone-guided lightning strike was achieved at the Shirone Giant Rocket Lightning Observation Tower and confirmed by high-speed cameras and current measurements. This technique has the potential to provide more controlled and precise lightning protection compared to traditional methods, such as lightning rods.
Hacker News users discussed the potential applications and limitations of the drone-based laser lightning rod. Some expressed skepticism about its practicality and cost-effectiveness compared to traditional lightning rods, questioning the feasibility of deploying drones during storms and the limited range of the laser. Others saw potential in protecting critical infrastructure like launchpads and power grids, or even using the technology for atmospheric research. A few comments focused on the technical aspects, like the laser's power requirements and the challenge of maintaining a precise beam in turbulent air. There was also interest in the potential ecological impact and safety concerns associated with inducing lightning strikes.
A new study suggests Earth's subtropical low-cloud zones are shrinking, allowing more sunlight to reach the ocean and accelerating global warming. By combining satellite observations with climate models, researchers found strong evidence that decreased cloud cover is a consequence of rising CO2 levels, and not just natural variation. This positive feedback loop, where warming reduces clouds which then leads to more warming, could amplify the effects of climate change beyond current projections. The study highlights the importance of low clouds in regulating Earth's temperature and underscores the potential for even more rapid warming than previously anticipated.
Hacker News users discuss the study's implications and methodology. Several express concern about the potential for a positive feedback loop, where warming reduces cloud cover, leading to further warming. Some question the reliability of satellite data used in the research, citing potential biases and the short timescale of observation. Others highlight the complexity of cloud behavior and the difficulty of modeling it accurately, suggesting the need for more research. A few commenters point to the broader context of climate change and the urgency of addressing it, regardless of the specific findings of this study. One compelling comment argues that reducing emissions remains crucial, even if this particular feedback mechanism proves less significant than suggested. Another highlights the potential impact of reduced cloud cover on ecosystems, particularly deserts.
Project Aardvark aims to revolutionize weather forecasting by using AI, specifically deep learning, to improve predictions. The project, a collaboration between the Alan Turing Institute and the UK Met Office, focuses on developing new nowcasting techniques for short-term, high-resolution forecasts, crucial for predicting severe weather events. This involves exploring a "physics-informed" AI approach that combines machine learning with existing weather models and physical principles to produce more accurate and reliable predictions, ultimately improving the safety and resilience of communities.
HN commenters are generally skeptical of the claims made in the article about revolutionizing weather prediction with AI. Several point out that weather modeling is already heavily reliant on complex physics simulations and incorporating machine learning has been an active area of research for years, not a novel concept. Some question the novelty of "Fourier Neural Operators" and suggest they might be overhyped. Others express concern that the focus seems to be solely on short-term, high-resolution prediction, neglecting the importance of longer-term forecasting. A few highlight the difficulty of evaluating these models due to the chaotic nature of weather and the limitations of existing metrics. Finally, some commenters express interest in the potential for improved short-term, localized predictions for specific applications.
Astronomers have detected incredibly fast winds, reaching speeds up to 10,000 mph (5 km/s), on the exoplanet HD 209458b. This hot Jupiter, already known for its evaporating atmosphere, has provided the first direct measurement of wind speeds on a planet outside our solar system. Researchers used high-resolution spectroscopy to observe carbon monoxide in the planet's atmosphere, tracking its movement with unprecedented precision and revealing these extreme supersonic winds blowing from the hot dayside to the cooler nightside. This breakthrough offers valuable insights into atmospheric dynamics on exoplanets and advances our understanding of planetary weather systems beyond our solar system.
HN commenters discuss the challenges and limitations of measuring wind speeds on exoplanets, particularly highlighting the indirect nature of the measurements and the assumptions involved. Some express skepticism, questioning the precision of such measurements given our current technology and understanding of exoplanetary atmospheres. Others are fascinated by the extreme conditions described and speculate about the implications for atmospheric dynamics and potential habitability. A few commenters point out the potential for future research with more advanced telescopes like the Extremely Large Telescope (ELT), hoping for more accurate and detailed data on exoplanetary atmospheres and weather patterns. There's also some technical discussion of the Doppler broadening technique used for these measurements and how it relates to atmospheric escape. Finally, some users question the newsworthiness, suggesting this is a relatively minor incremental advance in exoplanet research.
Researchers have demonstrated a method for using smartphones' GPS receivers to map disturbances in the Earth's ionosphere. By analyzing data from a dense network of GPS-equipped phones during a solar storm, they successfully imaged ionospheric variations and travelling ionospheric disturbances (TIDs), particularly over San Francisco. This crowdsourced approach, leveraging the ubiquitous nature of smartphones, offers a cost-effective and globally distributed sensor network for monitoring space weather events and improving the accuracy of ionospheric models, which are crucial for technologies like navigation and communication.
HN users discuss the potential impact and feasibility of using smartphones to map the ionosphere. Some express skepticism about the accuracy and coverage achievable with consumer-grade hardware, particularly regarding the ability to measure electron density effectively. Others are more optimistic, highlighting the potential for a vast, distributed sensor network, particularly for studying transient ionospheric phenomena and improving GPS accuracy. Concerns about battery drain and data usage are raised, along with questions about the calibration and validation of the smartphone measurements. The discussion also touches on the technical challenges of separating ionospheric effects from other signal variations and the need for robust signal processing techniques. Several commenters express interest in participating in such a project, while others point to existing research in this area, including the use of software-defined radios.
Summary of Comments ( 22 )
https://news.ycombinator.com/item?id=44073185
HN commenters largely enjoyed the article, calling it "fascinating," "well-written," and "mind-blowing." Several expressed surprise at the idea that we might be inhaling molecules of Caesar's last breath, with one noting the sheer scale of diffusion and another pointing out the unlikelihood of a specific molecule making the journey unchanged. Some discussed the implications for other historical figures and events, wondering about shared molecules from other points in history or the potential for "sniffing history" through preserved air samples. A few commenters delved into the math and science behind the claim, discussing Avogadro's number, atmospheric mixing, and the probability of inhaling ancient molecules. One commenter offered a counterpoint, suggesting the constant creation and destruction of molecules might make the claim less compelling.
The Hacker News post titled "Caesar's Last Breath" (linking to charliesabino.com/caesars-last-breath/) sparked a discussion with several interesting comments.
One commenter raises the point that the article's core premise – that we likely inhale some of the same molecules Julius Caesar exhaled in his dying breath – hinges on the assumption of uniform atmospheric mixing. They argue that while the concept is intriguing, the atmosphere isn't perfectly mixed, and factors like thermal inversions and varying wind patterns could influence the distribution of these molecules. This raises questions about the probability of inhaling Caesar's specific molecules as opposed to molecules from other historical figures or events.
Another commenter delves into the mathematical aspect, mentioning that while the calculation in the original article is correct, it doesn't account for the conversion of some exhaled molecules into other compounds over time. They suggest that considering factors like CO2 uptake by plants and the formation of carbonic acid in the oceans would further refine the calculation and likely decrease the probability of inhaling Caesar's original breath molecules.
Furthering the discussion about the atmosphere's composition, a commenter notes the significant increase in atmospheric gases due to human activities, especially since the industrial revolution. They argue that this increase dilutes the concentration of historical molecules even further. This suggests that while we might inhale molecules from Caesar's time, the proportion coming directly from his last breath is likely even smaller than initially estimated.
One commenter adds a philosophical layer to the discussion, contemplating the vastness of time and the interconnectedness of matter. They find the idea of sharing molecules with historical figures a humbling and thought-provoking reminder of our place within the larger universe.
Finally, a more technically inclined commenter mentions the concept of Avogadro's number and its significance in understanding the sheer number of molecules involved in these calculations. They emphasize the importance of considering the vastness of these numbers when grappling with the probabilities discussed in the article and subsequent comments.
Overall, the comments on Hacker News provide a nuanced perspective on the article's core idea, exploring the scientific, mathematical, and philosophical implications of inhaling molecules from the past. They highlight the complexities of atmospheric mixing and the various factors influencing the distribution and preservation of historical molecules.