Red Shift

When a MOVING object produces a WAVE, the FREQUENCY and WAVELENGTH of the wave CHANGES relative to a STATIONARY observer.

When the object producing the wave moves TOWARDS the observer the:

• FREQUENCY of the wave INCREASES
• WAVELENGTH of the wave DECREASES

When the object producing the wave moves AWAY from the observer the:

• FREQUENCY of the wave DECREASES
• WAVELENGTH of the wave INCREASES

This EFFECT can be applied to STARS and GALAXIES that give off LIGHT WAVES - The stars are the objects giving off the wave and the EARTH is the OBSERVER.

Light from stars and galaxies form a LIGHT SPECTRUM. These contain the all possible visible colours with DARK LINES at specific locations (wavelengths).

When comparing the LIGHT SPECTRUM from the SUN in our solar system to other GALAXIES, you observe that the dark lines on the GALAXY SPECTRUM has the SAME PATTERN as the Sun SHIFTED to the RED side of the spectrum.

Red light has a LOWER FREQUENCY and HIGHER WAVELENGTH than blue light, so this means that the GALAXY must be moving AWAY from our solar system (the object producing the wave is moving AWAY from the observer).

Another observation made is that the FURTHER AWAY a galaxy is, the GREATER the RED SHIFT.

This means that the FURTHER AWAY a galaxy is, the FASTER it moves away from us.

The Big Bang

ALL GALAXIES that we can observe show RED SHIFT, which tells us that ALL GALAXIES are moving away from us.

GALAXIES that are FURTHER from us show GREATER red shift than the ones closer to us, meaning they are moving EVEN FASTER away from us.

This provides evidence that the UNIVERSE is EXPANDING.

This means that if we look back in time, the galaxies must have started from the SAME POINT before "exploding outwards".

This RED SHIFT in galaxies provides evidence of the BIG BANG THEORY which suggests that the universe began from a very SMALL REGION that was extremely HOT and DENSE.

Scientist are able to use theories such as RED SHIFT to arrive at theories such as the BIG BANG THEORY, however it is important that new observations undergo PEER REVIEW. This is because:

• It detects FALSE CLAIMS
• It detects INACCURATE DATA
• It detects BIAS
• It VERIFIES new data

There is still much about the universe that is NOT understood, including DARK MATTER and DARK ENERGY.

eg. Since 1998 onwards, observations of supernovae suggest that distant galaxies are receding EVEN FASTER, which can NOT be explained by scientists. It has been suggested that this acceleration has been caused by "DARK ENERGY".