James Chadwick
Atomun parçalarından nötronu bulmasıyla tanınır.

İyi bir ilk ve orta eğitimden sonra Manchester üniversitesi fizik bölümünden 20 yaşında mezun oldu. Verilen bir burstan yararlanarak ve Geiger ile çalışmak amacıyla Almanya’ya gitti. Almanya savaşa girince bir at ahırına kapatıldı. Fakat çeşitli Alman fizikçilerinin yardımlarıyla 1919 yılında İngiltere’ye dönüp araştırmalarına başladı. Rutherford ile birlikte çeşitli elementlerin alfa parçacıklarıyla bombardımanı üzerinde çalıştı.

Bu deneylerden elde ettiği verileri atomların çekirdekleri üzerindeki artı yükün hesabında kullandı. Aldığı sonuçlar Moseley’in geliştirdiği atom numaraları kuramına uyuyordu.

1920 yılında atomun iki parçacığı olduğu biliniyordu: J.J. Thomson’un bulduğu elektron ve Rutherford’un keşfettiği proton. Protonların tamamı çekirdekteydi. Ama çekirdek atom kütlesinin çoğunu oluşturacak sayıda proton içeriyorsa yükü büyük bir artı değerde oluyordu. Örneğin, helyumun dört protonluk bir kütlesi vardı fakat yükü iki proton karşılığı idi. O halde, çekirdekte geri kalan iki protonluk yükü giderecek birkaç elektron bulunmalıydı. Fakat elektronlar çok hafif parçacıklar olduklarından kütleyi etkileyemezlerdi. Hatta elektronlar, protonları bir arada tutan “çimento” gibi düşünülüyordu. Çünkü elektron olmadan aynı yükteki protonların bir arada duramayıp ayrılacakları sanılıyordu. Bu görüşe göre, helyum çekirdeğinde dört proton ve iki elektron bulunmalıydı ki kütlesi dört ve yükü net artı iki olsun.


Kaynak: Türk bilim adamlarının adları ve hayatları hakkında bilgi verir misiniz?

Michael Jackson
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(Redirected from Michael jackson)
For other people named Michael Jackson, see Michael Jackson (disambiguation).

Michael Jackson's signature
Michael Joseph Jackson[1] (August 29, 1958 – June 25, 2009) was an American recording artist, entertainer, and businessman. Often referred to as the King of Pop, or by his initials MJ,[2] Jackson is recognized as the most successful entertainer of all time by Guinness World Records. His contribution to music, dance, and fashion, along with a much-publicized personal life, made him a global figure in popular culture for over four decades. The seventh child of the Jackson family, he debuted on the professional music scene along with his brothers as a member of The Jackson 5, then the Jacksons in 1964, and began his solo career in 1971.

In the early 1980s, Jackson became a dominant figure in popular music. The music videos for his songs, including those of "Beat It", "Billie Jean", and "Thriller", were credited with transforming the medium into an art form and a promotional tool, and the popularity of these videos helped to bring the relatively new television channel MTV to fame. Videos such as "Black or White" and "Scream" made him a staple on MTV in the 1990s. Through stage performances and music videos, Jackson popularized a number of complicated dance techniques, such as the robot and the moonwalk, to which he gave the name. His distinctive musical sound and vocal style have influenced numerous hip hop, post-disco, contemporary R&B, pop and rock artists.
Jackson's 1982 album Thriller is the best-selling album of all time. His other records, including Off the Wall (1979), Bad (1987), Dangerous (1991), and HIStory (1995), also rank among the world's best-selling. Jackson is one of the few artists to have been inducted into the Rock and Roll Hall of Fame twice. He was also inducted into the Dance Hall of Fame as the first (and currently only) dancer from the world of pop and rock 'n' roll. Some of his other achievements include multiple Guinness World Records; 13 Grammy Awards (as well as the Grammy Legend Award and the Grammy Lifetime Achievement Award); 26 American Music Awards (more than any other artist, including the "Artist of the Century"); 13 number-one singles in the United States in his solo career (more than any other male artist in the Hot 100 era); and the estimated sale of over 750 million records worldwide. Jackson won hundreds of awards, which have made him the most-awarded recording artist in the history of popular music.[3]

Aspects of Jackson's personal life, including his changing appearance, personal relationships, and behavior, have generated controversy. In 1993, he was accused of child sexual abuse, but the case was settled out of court and no formal charges were brought. In 2005, he was tried and acquitted of further child sexual abuse allegations and several other charges after the jury found him not guilty on all counts. While preparing for his concert series titled This Is It, Jackson died of acute propofol intoxication on June 25, 2009, after suffering from cardiac arrest. The Los Angeles County Coroner ruled his death a homicide, and his personal physician was convicted of involuntary manslaughter. Jackson's death triggered a global outpouring of grief, and as many as one billion people around the world reportedly watched his public memorial service on live television. In March 2010, Sony Music Entertainment signed a $250 million deal with Jackson's estate to retain distribution rights to his recordings until 2017, and to release seven posthumous albums over the decade following his death.

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