大象传媒

Big Bang Theory

According to the theory, about 13.8 billion years ago the whole Universe was a very small, extremely hot and dense region. From this tiny point, the whole Universe expanded outwards to what exists today.

Evidence from red-shift

Astronomers have discovered that, in general, the further away a galaxy is, the more red-shifted its light is. This means that the further away the galaxies are, the faster they are moving. This is similar to an explosion, where the bits moving fastest travel furthest from the explosion. Red-shift data provides evidence that the Universe, including space itself, is expanding.

Professor Brian Cox explains how evidence for the Big Bang can be found by analysing the colour of starlight

Evidence from CMBR

Astronomers have also discovered a cosmic microwave background radiation (CMBR). This comes from all directions in space and has a temperature of about -270 掳C. The CMBR is the remains of the thermal energy from the Big Bang, spread thinly across the whole Universe.

Prediction from Big Bang theoryEvidence observedDoes evidence support the Big Bang theory?
More distant galaxies should move away fasterMore distant galaxies have greater red-shiftYes
Initial Big Bang heat should now be thinly spread across the whole UniverseCMBR is everywhere at a temperature of about -270掳CYes
Prediction from Big Bang theoryMore distant galaxies should move away faster
Evidence observedMore distant galaxies have greater red-shift
Does evidence support the Big Bang theory?Yes
Prediction from Big Bang theoryInitial Big Bang heat should now be thinly spread across the whole Universe
Evidence observedCMBR is everywhere at a temperature of about -270掳C
Does evidence support the Big Bang theory?Yes

The discovery of red-shift in light from distant galaxies led to the development of the Big Bang theory. The discovery of the CMBR, after it had been predicted by the theory, provided very strong support for the Big Bang theory.