Multiwavelength Astronomy


Strong & Weak Nuclear Force

The Big Bang Theory states that during the first second of the Universe, all matter was broken down into sub-atomic particles. The strong nuclear force pulled positively and negatively charged quarks together to form positively charged protons and neutrally charged neutrons. The strong nuclear force also binds protons and neutrons in the nucleus of atoms. The weak nuclear force enabled complex atoms to form through nuclear fusion. If the strong and weak nuclear forces did not exist, then stars, galaxies, and planets would never have been formed.

Strong Nuclear Force: Two positive charges repel each other because of the electromagnetic force, so the strong nuclear force lives up to its name by overcoming the intense repulsion between similarly charged particles that coexist in the nucleus of atoms. When the strong nuclear force that binds protons and neutrons in an atom is broken, extreme high-energy photons are released in the process.

Weak Nuclear Force: The weak nuclear force can change a neutron into a proton in a process called nuclear decay. When the weak nuclear force converts a neutrally charged neutron into a positively charged proton, sub-atomic particles are released near the speed of light.

When the nuclei of atoms smash together or break apart, they often change their mass in the process. This gain or loss of mass corresponds to a loss or gain of energy, as well. The strong and weak nuclear forces are what enable fission and fusion energy to create the devastating power of nuclear weapons, as well as powering the core of stars.

High-energy X-ray and gamma ray astronomers study the radiation that results from the strong and weak nuclear force breaking down in the nucleus of atoms. The electromagnetic force repels protons from each other, but extreme high-energy events like supernova explosions and merging black holes can force protons to smash together and release a high-energy photon, so it is important to study high-energy radiation to understand how stars are created, how they function over time, and how they transform into neutron stars and black holes.

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This material is based upon work supported by NASA under Grant Nos. NNX09AD33G and NNX10AE80G issued through the SMD ROSES 2009 Program.

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