The Big Bang and the Future of the Universe

How do scientists know the Universe is expanding? Red shift video

Expanding Universe - summary Most stars have their light stretched towards longer wavelengths because they are moving away from us – this is called ‘Red Shift’. The further the stars are away the more the light has been stretched and therefore the faster they must be moving away. This can only be explained by a universe which is expanding.

Electromangetic (EM) Spectrum

The Big Bang Theory Microwave radiation Gamma radiation

Predictions In the late 1940s scientists used the Big Bang theory to predict that we should be able to ‘see’ the left over radiation from the Big Bang This radiation should have been stretched by expansion of space into the microwave part of the EM Spectrum

Accidental Discovery Two American scientists discovered the microwave radiation by accident in 1965 They were puzzled by the ‘hiss’ being collected by their radio-telescope

Cosmic Microwave Background Radiation

Big Bang Theory - summary Start of everything – space, time, matter ‘Explosion’, but different because not exploding into anything Cosmic Microwave Background radiation is left-over radiation from the Big Bang and provides strong support for the theory.

Future of the Universe The Big Rip The Big Yawn size The Big Crunch time

What is the future for the Universe? 1) Carries on expanding, stars burn out, everything cools – ‘Big Yawn’ 2) Eventually, gravity slows expansion and pulls matter closer together again – ‘Big Crunch’ 3) New evidence suggests that expansion is speeding up, possibly due to ‘Dark Energy’ – ‘The Big Rip’

Exploring Space

Telescopes - summary large is best outside the distorting effect of the atmosphere is better for optical and infrared wavelengths (e.g. Hubble) radio-telescopes operate in the radio and microwave region and are less affected by the Earth’s atmosphere, and are large. It is more cost effective to locate them on the ground.

What is dark matter? Up to 22% of the mass of the universe is invisible Material which doesn’t emit light or reflect it, so invisible Evidence comes from the rotational speed of galaxies and gravitational lensing

What is dark energy? Hypothetical form of energy that permeates all of space and has strong negative pressure Accelerating the expansion of the universe