A relativistic particle refers to a particle that is moving at speeds close to the speed of light, where the effects of Einstein's theory of relativity become significant. In the realm of classical physics, particles are described by Newtonian mechanics, which assumes that velocities are much less than the speed of light. However, when particles approach relativistic speeds (typically a significant fraction of the speed of light, denoted as \(c\)), their behavior can no longer be accurately described by classical mechanics.
A torus knot is a special type of knot that is tied on the surface of a torus (a doughnut-shaped surface). More formally, a torus knot is defined by two integers \( p \) and \( q \), where \( p \) represents the number of times the knot winds around the torus's central axis (the "hole" of the doughnut) and \( q \) represents the number of times it wraps around the torus itself.
A Universal Linear Accelerator (ULA) is a type of particle accelerator that uses electromagnetic fields to accelerate charged particles, such as electrons, protons, or ions, in a straight line. The term "universal" suggests that this type of accelerator can be adapted for various applications and can accelerate different kinds of particles.
Acoustic measurement refers to the process of quantifying various sound-related parameters in a given environment. These measurements are critical in various fields, including engineering, environmental science, music, architecture, and health. The following are common aspects of acoustic measurement: 1. **Sound Pressure Level (SPL)**: Measured in decibels (dB), this quantifies the pressure of sound waves in the air relative to a reference level.
A-weighting is a frequency weighting used in sound measurements to reflect the relative loudness perceived by the human ear. The human auditory system does not respond equally across all frequencies; it is more sensitive to mid-frequency sounds (typically around 1 kHz to 4 kHz) and less sensitive to very low and very high frequencies.
The absolute threshold of hearing refers to the minimum sound level that an average human ear can detect. It is the point at which a sound becomes audible and is typically measured in decibels (dB) relative to a standard reference level. The absolute threshold can vary based on several factors, including frequency and individual differences in hearing acuity.
Acoustic communication refers to the use of sound waves to convey information between individuals or systems. This form of communication can be observed in various contexts and across many species, including humans, animals, and artificial systems. Here are some key aspects of acoustic communication: 1. **Biological Communication**: In the animal kingdom, many species utilize acoustic signals for communication. For example, birds sing to attract mates, warn of predators, or establish territory.
Auralization is the process of creating sound simulations or reproducing audio environments in a way that allows listeners to perceive and experience an auditory scene as if they were present in that environment. It is often used in the fields of architecture, acoustics, and virtual reality, helping to visualize how sound will behave in a specific space before it is built or modified. The process typically involves the use of computer modeling and simulation tools that analyze how sound waves interact with various surfaces and objects within a given environment.
Induced characters refer to representations of a group that arise from the representation of a subgroup. In the context of representation theory—an area of mathematics that studies abstract algebraic structures through linear transformations—induced characters are a way to construct new representations of a group via a subgroup.
Acoustic radiation force is a phenomenon that occurs when an acoustic wave, such as ultrasound, interacts with an object or a medium. It results from the pressure variations produced by the sound waves as they propagate and can lead to a net force acting on small particles, bubbles, or biological tissues within the medium. ### Key Aspects of Acoustic Radiation Force: 1. **Mechanism**: When an ultrasound wave passes through a medium, it generates regions of high and low pressure.
Attenuation refers to the reduction in the strength or intensity of a signal as it travels through a medium. This concept is applicable in various fields, including telecommunications, acoustics, and optics. In general terms, attenuation can be described as the loss of energy or the decrease in amplitude of a signal due to factors such as: 1. **Distance**: As a signal travels further from its source, it typically loses strength.
Aeroacoustics is a branch of engineering and applied physics that studies the generation, propagation, and interaction of sound (acoustic phenomena) in fluid flows, particularly in air. It combines elements of fluid dynamics and acoustics to understand how aerodynamic forces and structures produce sound. Key areas of interest in aeroacoustics include: 1. **Sound Generation**: Investigating how different flow phenomena, such as turbulence, boundary layer interactions, and shock waves, create sound.
The projects you do must always aim to achieving some novel result.
You don't have to necessarily reach it. But you must aim for it.
Novel result can be taken broadly.
But there must be something to your project that has never been done before.
You can start by reproducing other's work.
What poor countries have to do to get richer Teach everyone English by
Ciro Santilli 40 Updated 2025-07-16
This is obviously the most efficient investment any non-English speaking country must do, because you need to know English to be able to learn from rich countries and innovate.
Further discussion at: Section "Having more than one natural language is bad for the world".
What poor countries have to do to get richer Pick few good bets and invest enough on them by
Ciro Santilli 40 Updated 2025-07-16
Therefore, you have to pick a few key the next big thing deep tech bets, and invest on those enough.
Therefore, the bets have to be well selected, because it is useless to make several insufficient investments: you have to pick a few ones, and put enough time and money into each one of them for them to stand any chance. These bets should be made and reevaluated on 5/10 year horizons.
The key things that you have to select are:
- which poor students you will bet on educating. Since you can't give amazing education to everyone, you have to select the most promising poor students somehow, and give those free amazing learning conditions: free gifted education
- which ares to focus on. Ciro believes that molecular biology technologies and quantum computing would be good bets. Focusing on the previous next big things, e.g. classic computers, is always a losing bet on average
And then you only tax those companies heavily when the start to bring in real money. These are startups remember! You only need 5 unicorns a year to call it a success. And countries should not be greedy and invest through equity, but rather recoup their investment through taxation alone.
Ciro's second removed uncle, who was a physicist at the University of Campinas, one of the best universities in the country, told him an anecdote. He had moved from fusion energy research to solar cell research. At some point, there was a research lab that needed 10 million to buy a machinery critical for their experiment. They asked and asked, and finally the government gave them only 2 million. So in the end they spent those 2 million in random ways, but of course did not achieve their research goal and no money came out of it.
He also explained how as a result of the insufficient investments, he felt clearly that some of the semiconductor production facilities related to solar power he saw simply were not able to control the production process adequately to produce consistent silicon. As a result, everything failed sooner or later as people found more and more bugs that they did not have the time to solve.
Another key investment is enticing back experienced exchange-students who have learnt new techniques to be heads of laboratory/founders to back in your country.
A fantastic initiative from Brazil for example is BRASA, which aims to put together Brazilian exchange students to make a difference back in Brazil.
Do not try to forbid external companies from selling in your country. Instead, fund your own companies to be able to fight the external market off. And if they can't, let them die and pick a different bet. Video "How Taiwan Created TSMC by Asianometry (2020)" has a good mention. Protectionism is something that Brazil notably tried to do, and look at what it led, not a single international success.
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!
Intro to OurBigBook
. Source. We have two killer features:
- 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-calculusArticles 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/derivativeVideo 2. OurBigBook Web topics demo. Source. - 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.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
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. - Infinitely deep tables of contents:
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





