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The life cycle of stars and the universe
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Stars are born, live and die over billions of years. Light from distant galaxies tells us the universe is expanding. Separate Physics only.
Life cycle of a star like the Sun
Nebula (dust and gas) → protostar → main sequence star (fusion, stable) → red giant → white dwarf.
Massive stars
Main sequence → red supergiant → supernova → neutron star or black hole.
A star is stable when the inward force of gravity balances the outward pressure from fusion.
A star is stable when the inward force of gravity balances the outward pressure from fusion.
The expanding universe
Light from distant galaxies is red-shifted: its wavelength is stretched.
The further away a galaxy, the bigger the red-shift, so the faster it is moving away.
This supports the Big Bang theory. The cosmic microwave background (CMB) radiation is further evidence.
The further away a galaxy, the bigger the red-shift, so the faster it is moving away.
This supports the Big Bang theory. The cosmic microwave background (CMB) radiation is further evidence.
Why does red-shift support the Big Bang theory?
- Red-shift shows galaxies are moving away.
- Further galaxies move away faster.
- So the universe is expanding from a starting point.
Answer: It shows the universe is expanding.
Sun-like stars: nebula, protostar, main sequence, red giant, white dwarf. Massive stars: red supergiant, supernova, neutron star or black hole. Red-shift and the CMB support the Big Bang.
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