That big bang idea - Fred Hoyle

That big bang idea - Fred Hoyle

The Father of the Big Bang Theory

• Father Georges-Henri Lemaître, 1984-1966 , proposed his theory in, 1927.
• Using Albert Einstein’s General Relativity, Lemaître derived equations and proposed, on the basis of the recession of spiral nebulae that the universe began with the “explosion” of the “primeval atom”.
• Fred Hoyle coined the name “Big Bang” by referring to Lemaître's theory as “this big bang idea”.

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Foundations of Big Bang
• General Relativity
– The presence of matter bends space-time, and this curvature affects all free particles.

• Cosmological Principle
– A reasonable assumption or axiom that states:
• On larger scales, the universe is homogeneous and isotopic.

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The Observations.
• In 1929, Edwin Hubble announced that galaxies outside the Milky Way were systematically moving away from us with a speed proportional their distance from us. This phenomenon was observed as a cosmological redshift of a galaxy spectrum.

• Hubble’s Law of Expansion
– The further an object, the faster it is traveling.
– V = Recessional velocity of distant object.
– H0 = Hubble’s constant, measured to be (71+/- 5%)km/s/Mpc by WMAP probe recently.
– D = Distance of the object

• Cosmic Microwave Background Radiation
– The Big Bang theory predicted that cosmic microwave background radiation had a near perfect blackbody spectrum and it anisotropies.
• In 1964, Arno Penzias and Robert Wilson discovered cosmic background radiation accidentally when they tried to find the source of interference on the SHF band microwave links.

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Observations. So?
• This observations tells us a few things.
– Since the galaxies are moving apart today, they must have been closer in the past.
• This implies that very long ago, these galaxies would be at the same point.

• Big Bang Theory predicted the existence of background radiation.
– The existence of CMB is confirmed.
• Gives evidence that Big Bang is the start of the universe