The photovoltaic effect is the creation of electric voltage or electric current in a material upon exposure to light. This phenomenon is the foundational principle behind photovoltaic cells, commonly known as solar cells, which are used to convert sunlight into electricity. Here's a more detailed explanation: 1. **Material Properties**: The photovoltaic effect occurs in certain materials, typically semiconductors, such as silicon. These materials have a band gap that allows them to absorb photons (light particles) with sufficient energy.
St. Elmo's fire is a phenomenon that occurs during thunderstorms, characterized by a visible blue or violet glow. It is caused by the ionization of air surrounding pointed or sharp objects, such as the mast of a ship or the spire of a church. When the electric field in the atmosphere becomes strong enough, it creates a discharge of electricity that results in a gentle and continuous glow at the tips of these objects. St.
The Goos–Hänchen effect is a phenomenon observed in the field of optics and wave physics, particularly in the context of total internal reflection. It describes the lateral displacement of a light beam when it reflects off the boundary between two different media at an angle greater than the critical angle. When a light wave hits the interface between two media (like air and glass) at an angle greater than the critical angle, it undergoes total internal reflection.
Lens flare is a phenomenon that occurs when a bright light source, such as the sun or a strong artificial light, hits the lens of a camera or optical device. This can result in unwanted artifacts, such as bright spots, halos, or streaks of light, appearing in the image. These artifacts are caused by internal reflections within the lens elements, scattering of light, and other optical effects.
In optics, "gloss" refers to the shine or luster of a surface, which is primarily determined by how that surface reflects light. Glossy surfaces have a smooth texture that allows for specular reflection, meaning that they reflect light in a coherent direction, resulting in a shiny appearance. This is in contrast to matte surfaces, which have a rougher texture that scatters light in many directions, leading to a dull appearance.
Fiction about black holes often explores themes of science, philosophical inquiry, and the unknown. Here are some common aspects and examples found in various forms of media: 1. **Science Fiction Novels and Stories**: - *Interstellar* (film) and the accompanying novelization by Kip Thorne, delve into the concept of black holes as wormholes for space travel and explore the relativity of time. - In Arthur C.
Black hole cosmology is a theoretical framework that explores the relationship between black holes and the overall structure and evolution of the universe. This field of study investigates various aspects of cosmology—including the origin and fate of the universe—through the lens of black hole physics. Some of the key concepts and ideas in black hole cosmology include: 1. **Black Holes as Cosmic Structures**: Black holes can play a significant role in the formation of galaxies and large-scale structures in the universe.
Fuzzball is a concept within string theory, specifically in the context of understanding black holes and the nature of their information content. The term "fuzzball" is typically associated with the work of various researchers, particularly Samir Mathur and collaborators, who proposed that black holes in string theory may not be the singular, compact objects that are often depicted in classical physics.
A Gravastar, or "gravitational vacuum star," is a theoretical astrophysical object proposed as an alternative to black holes. The concept was introduced by physicist Pawel Mazur and Wojciech Zurek in the early 2000s. Gravastars are thought to be composed of a "vacuum" or "negative energy" state surrounded by a shell of exotic matter, which might be able to resist gravitational collapse.
The term "non-expanding horizon" typically refers to a concept in various fields such as economics, decision-making, and optimization, particularly in the context of time and strategic planning. Here’s a general overview of what it means: 1. **Definition**: In decision-making contexts, a non-expanding horizon is a situation where the timeframe for making decisions does not extend or increase as time progresses. In other words, when making decisions, the planner considers only a fixed time period.
The Penrose process is a theoretical mechanism in general relativity that describes how energy can be extracted from a rotating black hole. Named after the physicist Roger Penrose, who proposed it in 1969, the process exploits the unique features of a rotating black hole, specifically the phenomenon associated with its event horizon and ergosphere. Here's a simplified explanation of how it works: 1. **Rotating Black Hole**: A black hole that rotates is described by the Kerr solution to Einstein's equations.
A rotating black hole, also known as a Kerr black hole, is a type of black hole characterized by its rotation around an axis. The concept was first formulated by mathematician Roy P. Kerr in 1963. Unlike non-rotating (Schwarzschild) black holes, which are spherically symmetric, rotating black holes have an axial symmetry and are described by more complex mathematical structures.
PSR B0943+10 is a pulsar, which is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. As the neutron star rotates, this beam can be observed from Earth as it sweeps across our line of sight, producing a series of pulses, typically in the radio wavelength. Discovered in 1968, PSR B0943+10 is notable within the pulsar community for several reasons.
Verilator by Ciro Santilli 37 Updated 2025-07-16
Verilog simulator that transpiles to C++.
One very good thing about this is that it makes it easy to create test cases directly in C++. You just supply inputs and clock the simulation directly in a C++ loop, then read outputs and assert them with assert(). And you can inspect variables by printing them or with GDB. This is infinitely more convenient than doing these IO-type tasks in Verilog itself.
Some simulation examples under verilog.
First install Verilator. On Ubuntu:
sudo apt install verilator
Tested on Verilator 4.038, Ubuntu 22.04.
Run all examples, which have assertions in them:
cd verilator
make run
File structure is for example:
Example list:
Radiative levitation is a physical phenomenon that occurs when an object is suspended in space due to the balance between the forces of radiation pressure and gravitational pull. This effect is most commonly observed in environments where the radiation intensity is high, such as in stellar atmospheres or in the vicinity of certain types of lasers. In radiative levitation, the force exerted by the radiation (typically photons) can counteract the force of gravity.
The Lambda point refers to a specific temperature at which helium transitions from a normal fluid phase to a superfluid phase. This occurs at around 2.17 Kelvin (K) for helium-4, one of the isotopes of helium. At the Lambda point, the specific heat capacity of helium-4 diverges, which is indicative of a phase transition.
New England's Dark Day refers to a significant historical event that took place on May 19, 1780. On this day, an unusual darkening of the sky occurred across parts of New England, particularly in Connecticut, and extended into other northeastern states. The cause of this phenomenon was not immediately understood, leading to widespread speculation and fear.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact