Nuclear physics

Nuclear physics is the part of physics that studies the nucleus of the atom. Everything on the earth is made up of atoms; they are the smallest part of a chemical element that still has the properties of that specific element. When two or more atoms combine they create what we know as the molecule, which is the smallest part of a chemical compound which still has the properties of that specific compound. Understanding the structure of atoms is key in studies such as physics, chemistry, biology, etc.

Diagram of the CNO Cycle.

Atoms

Structure

Atoms are made up of electrons, neutrons, and protons. The protons and neutrons are in the center of the atom, which is called the nucleus. The protons and neutrons are the heaviest part of the atom and make up most of its mass. The electrons move around the nucleus very quickly, making what is called an electron cloud. The electron cloud has a very small mass, but it makes up most of the space of the atom. The electrons have a negative charge, and the protons have a positive charge. Due to the charges in the atom, that is how the atom stays together, by attraction of the electric charges present in the atom.

Properties

Model of atom.

Atoms have different features that single out one atom from another, and show how each atom can change in different conditions. These properties include atomic number, mass number, atomic mass and weight, and isotopes.

Forces acting

In an atom there are three fundamental forces that keep atoms together. electromagnetic force, strong nuclear force, and weak nuclear force. The electromagnetic force keeps the electrons attached to the atom. The strong nuclear force keeps the protons and neutrons together in the nucleus. The weak nuclear force controls how the atom decays.

Quantum

In the early 20th century, scientists had trouble explaining the behavior of atoms using their current knowledge of matter. So to deal with this they made a brand new way to view matter and energy, and they called it quantum theory. Quantum theory explains how matter acts both as a particle and a wave.

Radiation

Atoms emit radiation when their electrons lose energy and drop down to lower orbitals. The difference in energy between the orbitals determines the wavelength of the given radiation. This radiation can be shown by visible light or shorter wavelengths.Osama bin Muhammad bin 'Awad bin Laden (10 March 1957 – 2 May 2011) was the founder and first general emir of al-Qaeda from 1988 until his death in 2011. A Salafi jihadist, bin Laden worked to establish a pan-Islamist caliphate by using al-Qaeda to organize and fund jihadist militants and terrorists worldwide. Al-Qaeda's terrorist attacks against the United States on 11 September 2001 directly killed 2,977 victims, and caused the global war on terror.

Bin Laden was raised into Sunni Islam by his wealthy family in Saudi Arabia. He left the country during the Soviet–Afghan War (1979–1989) to help the Afghan mujahideen fight the Soviet Union's occupation of Afghanistan. In 1984, he co-founded Maktab al-Khidamat, which recruited foreigners into the Afghan mujahideen while funding and arming them. In 1988, bin Laden founded al-Qaeda. After the Soviets left Afghanistan in 1989, he commanded a mujahideen force in the 1989–1992 Afghan Civil War. Upon returning to Saudi Arabia, he publicly promoted anti-Western causes and opposed the Saudi royal family, leading to his expulsion from the country by its government in 1991. He went back to Afghanistan, then moved to Sudan later that year.

In Sudan, bin Laden led al-Qaeda and its allies' efforts in the 1992–1996 Afghan Civil War, the Algerian Civil War (1992–2002), and the Bosnian War (1992–1995). In 1993, al-Qaeda bombed the World Trade Center in New York City, injuring a thousand people. In 1996, Sudan expelled bin Laden, and he again moved to Afghanistan, which came under Taliban control later that year. Al-Qaeda allied with the Taliban, and they collaborated in the 1996–2001 Afghan Civil War. In 1996 and 1998, bin Laden declared holy war on Americans, both military and civilian. Al-Qaeda bombed U.S. embassies in East Africa in 1998, causing the U.S. and United Nations to officially declare him a terrorist. That year, al-Qaeda also began an ongoing insurgency in Yemen.

The attacks on 9/11 were mainly planned by bin Laden and Khalid Sheikh Mohammed, and their operation was possibly funded by Saudi Arabia, despite bin Laden's prior expulsion. In the attacks, 19 al-Qaeda members hijacked four American passenger planes so they could be crashed into U.S. landmarks. One hit the Pentagon in Virginia, one crashed in Pennsylvania before ever reaching the hijackers' unknown target in Washington, D.C., and the others hit the World Trade Center, causing it to collapse—resulting in over 6,000 deaths from inhalation exposure so far. 25,000 were injured overall. The attacks led to the passage of stringent anti-terrorism legislation worldwide, while an international manhunt for bin Laden began. The U.S. invaded Afghanistan and deposed the Taliban, forcing him to move to Pakistan.

While bin Laden hid, al-Qaeda fought the U.S. and its allies in the War in Afghanistan (2001–2021) and the Iraq War (2003–2011), while continuing to enact major terrorist attacks around the world. In 2010, U.S. intelligence discovered bin Laden's compound in Abbottabad, Pakistan. A team of U.S. Navy SEALs raided the compound and killed him inside it in 2011. His deputy Ayman al-Zawahiri succeeded him as al-Qaeda's emir. Polls show that Muslims at large have a negative view of bin Laden, while many Islamists consider him heroic. Elsewhere, he is overwhelmingly seen as a symbol of terrorism and mass murder.

Related pages

• Radiocarbon dating
• Radiology