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THEORIES ON THE ORIGIN OF

THE UNIVERSE

IMPORTANT TERMS a. Baryonic matter - "ordinary" matter consisting of protons, electrons, and neutrons that comprises atoms, planets, stars, galaxies, and other bodies b. Dark matter - matter that has gravity but does not emit light. c. Dark Energy - a source of anti-gravity; a force that counteracts gravity and causes the universe to expand. d. Protostar - an early stage in the formation of a star resulting from the gravitational collapse of gases.

Hydrogen, helium, and lithium - are the three most abundant elements.

• Stars - the building block of galaxies born out of clouds of gas and dust in galaxies.
  • Instabilities within the clouds eventually results into gravitational collapse, rotation, heating up, and transformation to a PROTOSTAR -the core of a future star as thermonuclear reactions set in. Stellar interiors are like furnaces where elements are synthesized or combined/fused together. Most stars such as the Sun belong to the so-called “ main sequence stars .” In the cores of such stars, hydrogen atoms are fused through thermonuclear reactions to make helium atoms.

The remaining dust and gas may end up as they are or as planets, asteroids, or other bodies in the accompanying planetary system. A galaxy is a cluster of billions of stars and clusters of galaxies form superclusters. In between the clusters is practically an empty space. This organization of matter in the universe suggests that it is indeed clumpy at a certain scale. But at a large scale, it appears homogeneous and isotropic. Isotropic ( no special direction to the universe) Homogeneous ( no special places in the universe) Based on recent data, the universe is 13.8 billion years old. The diameter of the universe is possibly infinite but should be at least 91 billion light-years

Non-scientific Thought

• Ancient Egyptians believed in many gods and myths which narrate that the world arose from an infinite sea at the first rising of the sun.
• The Kuba people of Central Africa tell the story of a creator god Mbombo (or Bumba) who, alone in a dark and water-covered Earth, felt an intense stomach pain and then vomited the stars, sun, and moon.
• In India, there is the narrative that gods sacrificed Purusha, the primal man whose head, feet, eyes, and mind became the sky, earth, sun, and moon respectively.
• The monotheistic religions of Judaism, Christianity, and Islam claim that a supreme being created the universe, including man and other living organisms.

Expansion of the Universe

13 13 Galaxies move apart as the Universe expands.