Rikunarita-ORG/Wikinium huggingface dataset:
# European Russia

Part of Russia situated on the European continent (c. 23%)
Russia is a country that stretches from Eastern Europe to North Asia. It is the largest and most populous country in Europe.

About twenty-five percent of Russia's land is on the European continent. The other seventy-five percent is on the Asian continent. Russia is a very big country; the land in the European part alone makes up 35% of the surface of Europe.

## Population

About 110 million of the 144 million people in Russia, or 80%, live in the European part. The other 20% live in the Asian part of Russia (Siberia).

About 15% of the population of Europe lives in the European part of Russia.

In the European part, the population density is 27.5 people per square kilometer. In Siberia, there are just 2.5 people per square kilometer.

## Cities

Russia's biggest cities, Moscow and Saint Petersburg, are in the European part. Moscow is the biggest city in Russia, with a population of 12,737,400 people (as of 2025).
# Physicist

A **physicist** is a scientist who studies physics.

Here are some famous physicists:

* Robert J. Lang
* Albert Einstein
* Archimedes
* Benjamin Franklin
* Blaise Pascal
* Enrico Fermi
* Erwin Schrödinger
* Galileo Galilei
* Henri Poincaré
* Isaac Newton
* James Watt
* Johannes Kepler
* Julius Robert Oppenheimer
* Leó Szilárd
* Marie Curie
* Max Planck
* Donna Strickland
* Niels Bohr
* Nikola Tesla
* Rene Descartes
* Richard Feynman
* Satyendra Nath Bose
* Stephen Hawking
* Werner Heisenberg
* C.V. Raman
* Abdul Kalam
* Jagadish Chandra Bose
# Half-life (physics)

Simulation of many identical atoms undergoing radioactive decay, starting with either 4 atoms per box (left) or 400 (right). The number at the top is how many half-lives have elapsed. Note the law of large numbers: With more atoms, the overall decay is more regular and more predictable.

| Number of half-lives over | Parts remaining | As power of 2 |
| --- | --- | --- |
| 0 | 1/1 |  WIKINIUM\_MATH\_PH\_0  |
| 1 | 1/2 |  WIKINIUM\_MATH\_PH\_2  |
| 2 | 1/4 |  WIKINIUM\_MATH\_PH\_4  |
| 3 | 1/8 |  WIKINIUM\_MATH\_PH\_6  |
| 4 | 1/16 |  WIKINIUM\_MATH\_PH\_8  |
| 5 | 1/32 |  WIKINIUM\_MATH\_PH\_10  |
| 6 | 1/64 |  WIKINIUM\_MATH\_PH\_12  |
| 7 | 1/128 |  WIKINIUM\_MATH\_PH\_14  |
| 8 | 1/256 |  WIKINIUM\_MATH\_PH\_16  |
| 9 | 1/512 |  WIKINIUM\_MATH\_PH\_18  |
| 10 | 1/1024 |  WIKINIUM\_MATH\_PH\_20  |
| ... | ... |
|  WIKINIUM\_MATH\_PH\_22  |  WIKINIUM\_MATH\_PH\_24  |  WIKINIUM\_MATH\_PH\_26  |

The **half-life** of a substance is the time it takes for half of the substance to decay. The word "half-life" was first used when talking about radioactive elements where the number of atoms get smaller over time by changing into different atoms. It is now used in other situations, such as the time it takes for a drug in the body to be half gone. A Geiger-Muller detector can be used to measure the radioactive half-life; it is the time when the activity is half the original.

Half-life depends on probability because the atoms decay at a random time. Half-life is the expected time when half the number of atoms have decayed, on average.

Radioactive isotopes are atoms that have unstable nuclei, meaning that the nucleus of each atom will decay after enough time has passed. Their nuclei are unstable because the arrangement of protons and neutrons in them change. This is known as radioactive decay. When they decay, they release particles such as alpha particles, beta particles, gamma rays. Sometimes they decay by fission, which means to break into pieces, to make smaller nuclei. For example, a radioactive carbon-14 atom releases a beta particle to become nitrogen-14. As an example of fission decay, a fermium-256 atom can split into xenon-140 and palladium-112 atoms, releasing four neutrons in the process.

Uranium-232 has a half-life of about 69 years. Plutonium-238 has a half-life of 88 years. Carbon-14, which is used to find the age of recent fossils, has a half-life of 5,730 years.

After ten half-lives, about 99.9% of the atoms have decayed into different atoms, so only 0.1% of the original atoms are left, and 99.9% of the radioactivity from the original kind of atom is gone. Some atoms decay into other atoms that are also radioactive, so the remaining radioactivity depends on the type of atom.

An example of a short half-life: the isotope, 260Sg, has a half-life of approximately 4 ms (or 4 thousandths of a second).

## Related pages

* Biological half-life
* Period 8 element
* List of radioactive nuclides by half-life

## Other websites

* Online chart of isotopes by half-life from the National Nuclear Data Center
# De revolutionibus orbium coelestium

'Heliocentric model' of the solar system with the Sun in the centre. Copernicus' manuscript
Title page of first edition
De revolutionibus orbium coelestium (*On the revolutions of the heavenly spheres*) is great work of the Renaissance astronomer Nicolaus Copernicus (1473–1543).

The book, first printed in 1543 in Nuremberg, Holy Roman Empire of the German Nation, offered proof that the Earth went round the Sun, and not vice versa, as had been thought.

This was an alternative model of the universe to Ptolemy's Earth-centered system, which had been accepted since ancient times.

Copernicus had worked his ideas out many years before, however he did not publish until right before his death because he himself did not truly believe it and only proposed the idea as a philosophy experiment.

## Contents

In its standard English edition, the book contains 330 folio pages, 100 pages of tables, and over 20,000 tabulated numbers.

The book is dedicated to Pope Paul III in a preface that argues that mathematics, not physics, should be the basis for understanding and accepting his new theory.

*De revolutionibus* is divided into six "books" (sections or parts):

* Book I is a general vision of the heliocentric theory, and a summarized exposition of his cosmology.
* Book II is mainly theoretical and describes the principles of spherical astronomy and a list of stars, as a basis for the arguments developed in the following books.
* Book III describes the apparent movements of the Sun and related phenomena.
* Book IV is a similar description of the Moon and its orbital movements.
* Books V and VI are the exposition of the new system. They explain how to calculate the positions of astronomical objects based on the heliocentric model.

This book is often referred to as the start of modern science.
# Orbital period

The **orbital period** is the time taken for a given object to make one complete orbit around another object. The year and month are orbital periods.

When mentioned without further qualification in astronomy this refers to the **sidereal period** of an astronomical object, which is calculated with respect to the stars. Other periods include the synodic period, which is the interval between conjunctions.
# Chengdu

Liu Shizhuang's house
**Chengdu** (also called The Hibiscus City), is the fifth largest city in the People's Republic of China. It is the capital of Sichuan province and is on top of the Chengdu Plain. The city is home to the Chengdu Research Base of Giant Panda Breeding. The city has a famous food culture, so much so that UNESCO awarded the city as a City of Gastronomy. Chengdu is known for hot pot and teahouses and for adding chili peppers in much of their food.
# Gross register tonnage

**Gross Register Tonnage** is the amount of space within the hull of a ship. It is the measure of how much cargo, stores, fuel, passengers and crew it can take.