What is the universe made of ? (Fermions and Bosons)

There are possibly only two classes of ‘particles’ in the universe – Fermions and Bosons. All elementary particles (Quarks, Leptons, Guage Bosons, Static Bosons etc.) will fall under either of these two. Not only elementary particles, but also composite particles like Baryons (Eg: Protons, Neutrons etc.) will also fall under this basic classification of all particles into Fermions and Bosons. The scheme of Quantum Field Theory...

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Which Car Had Been Driven On the Moon?

The American Apollo program 15,16 and 17 that travelled to the moon during 1971 and 1972 carried Lunar Roving Vehicles(LRVs) or Moon buggies. The astronauts (on Apollo 15 by astronauts David Scott and Jim Irwin, one on Apollo 16 by John Young and Charles Duke, and one on Apollo 17 by Eugene Cernan and Harrison Schmitt) drove the electric buggies around the moon's surface, looking for interesting rocks. The Apollo Lunar Roving Vehicle...

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Earth's Magnetic Field

Magnetic fields are produced by the motion of electrical charges. For example, the magnetic field of a bar magnet results from the motion of negatively charged electrons in the magnet. The origin of the Earth's magnetic field is not completely understood, but is thought to be associated with electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel....

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Astronomical Distance Scales

Some Common Distance Units: Light Year: the distance that light travels in one year (9.46 x 10^17 cm). Parsec (pc): 3.26 light years (or 3.086 x 10^18 cm).; also kiloparsec (kpc) = 1000 parsecs and megaparsec (Mpc) = 1,000,000 parsecs. Astronomical Unit (AU): the average separation of the earth and the sun (1.496 x 10^13 cm). Some Representative Distances: The Solar System is about 80 Astronomical Units in diameter. The...

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Hubble's constant (Hubble's Law)

The Hubble constant H is one of the most important numbers in cosmology because it may be used to estimate the size and age of the Universe. Hubble constant indicates the rate at which the universe is expanding. Although the Hubble "constant" is not really constant because it changes with time (and therefore should probably more properly be called the "Hubble parameter"). The Hubble constant is often written with a subscript "0"...

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