Even though Einstein thought of many ideas that helped scientists understand the world much better, he disagreed with some scientific theories that other scientists liked. The theory of quantum mechanics discusses things that can happen only with certain probabilities, which cannot be predicted with more precision no matter how much information we might have. This theoretical pursuit is different from statistical mechanics, in which Einstein did important work. Einstein did not like the part of quantum theory that denied anything more than the probability that something would be found to be true of something when it was actually measured; he thought that it should be possible to predict anything, if we had the correct theory and enough information. He once said, "I do not believe that God plays dice with the Universe."
Because Einstein helped science so much, his name is now used for several different things. A unit used in photochemistry was named for him. It is equal to Avogadro's number multiplied by the energy of one photon of light. The chemical element Einsteinium is named after the scientist as well. In slang, we sometimes call a very smart person an "Einstein."
Most scientists think that Einstein's theories of special and general relativity work very well, and they use those ideas and formulas in their own work. Einstein disagreed that phenomena in quantum mechanics can happen out of pure chance. He believed that all natural phenomena have explanations that do not include pure chance. He spent much of his later life trying to find a "unified field theory" that would include his general relativity theory, Maxwell's theory of electromagnetism, and perhaps a better quantum theory. Most scientists do not think that he succeeded in that attempt.
Euro
Euro is the currency (money) of the countries in the eurozone. One euro is divided into 100 "cent" (officially) (singular) or "cents" (unofficially).
Because of the number of different languages in the European Union, there are different, unofficial, names for this unit (the French call them "centimes" and the Spanish "céntimos", for example).
It was created in 1999, but until 1 January 2002 it was used only for electronic payments. In 2002, 12 countries of the European Union (EU) took their state currencies out of circulation and adopted euro notes and coins as their only money. There was a change-over period, called the ""transition period"", when both the old national money and the euro were accepted, but by 28 February 2002, all 12 countries were using just euros.
In 2006, Slovenia became the 13th country to use the euro. In 2008 Cyprus and Malta became the 14th and 15th countries to use the euro. In 2009, Slovakia became the 16th country to use the euro. In 2011, Estonia became the 17th country to use the euro. In 2014, Latvia became the 18th country and in 2015, Lithuania became the 19th country to use the euro.
There are seven different banknotes, each one with a different colour, size and face value: €5 (grey), €10 (red), €20 (blue), €50 (orange), €100 (green), €200 (yellow), €500 (purple).
Coins are of eight different amounts: €0.01, €0.02, €0.05, €0.1, €0.2, €0.5, €1, €2.
On every banknote, there is a picture of a different European building style. All banknotes are the same throughout the entire eurozone; there are no different designs for different countries, unlike the euro coins. One side of each coin is the same in all euro countries. The other side is different since each country who mints the coins inserts a symbol relating to that country. Today there are many different sets of coins. Any of the coins can be used everywhere throughout the eurozone despite the country-specific symbol on the back.
The ten new European countries that entered the European Union in May 2004 are planning to adopt the Euro also. First they must meet some conditions to show that they have stable economies.
The symbol for the euro is the Greek letter epsilon (E) with two horizontal lines: €.
Some people see it as the Latin capital letter C with an equal sign (=).
It is also legal to simply write "euro". This is especially useful when the symbol cannot be produced, or the result is not satisfactory.
Members of the eurozone are:
These countries form the Economic and Monetary Union (EMU).
Even though they are not part of the EU, the euro is also the currency used in:
Many other countries' currencies are "pegged" (tied) to, although not exactly equal to, the euro:
Currency
Currency is the unit of money used by the people of a country or Union for buying and selling goods and services.
Certain currencies are said to be "pegged" or "fixed" to something, usually another currency. A fixed or pegged currency is one that has a constant value compared to what it is pegged to. For example, the Cape Verdian escudo is pegged to the Euro. If the value of the Euro goes up 1% compared to another form of currency, the value of the escudo also goes up 1% compared to that same currency.
Many countries have used systems where their currency was pegged to a commodity rather than to another currency. Most used either gold or silver. When they did this, as the value of gold increased, so did the value of their money. This was called the "gold standard" or "silver standard". Most countries stopped using silver and gold standards in the 20th century.
Some well-known currencies are:
This list appears in alphabetical order:
Mercure
Mercure may refer to:
Radio telescope
A radio telescope is a type of antenna, like a huge satellite television dish. It is used for radio astronomy. Stars shine and the light can be seen with an ordinary telescope, but they also give off radio waves. Scientists with radio telescopes receive these radio waves and use computers to learn about the stars. Other things like black holes also give off radio waves and radio telescopes are useful for learning about them too.
The dish is sometimes constructed of a conductive wire mesh whose openings are smaller than a wavelength. The information received by several radio telescopes in different places can be combined. This gives similar results to having a single dish as big as the distance between the telescopes. It can receive very faint signals, and see more details. The biggest telescope is a virtual radio telescope almost as big as the Earth, called the Event Horizon Telescope.
The radio telescope at the Parkes Observatory, Parkes, New South Wales was used by NASA to receive messages from the Apollo 11 moon landings.
Light year
A light year (symbol: ly) is the distance that light travels in empty space in one year. Since the speed of light is about 300,000 km per second (about 186,000 miles per second), then a light year is about 10 trillion kilometers (about 6 trillion miles). A light year is not a length of time.
The light year is used in astronomy because the universe is huge. Space objects such as stars and galaxies may be hundreds, thousands or millions of light years away.
Think of a star at a distance of 100 light years from us on Earth. Light leaves the star and takes 100 years to get to us. When we see the star's light, we are seeing that star as it was 100 years ago.
Korea
Korea is a peninsula in northeast Asia. It covers a peninsula called the "Korean Peninsula". Korea became a country (or state) in 918. In 1948, it split into two countries: North Korea and South Korea. North and South Korea and their allies fought against each other in the Korean War.
People have lived in Korea for about 15,000 years. In the past, some of modern Manchuria and Siberia was governed by Korea. Korea is known for its fine silk. In the 7th century, the people of China sought after gold-workers from Korea. Europeans had little knowledge about Korea until the modern era.