Cosmology

 

“The whole Universe was in a hot, dense state and nearly 14 billion years ago expansion started” - it’s best to sing the Big Bang Theory theme tune to remember the rough age of the universe.

But how do we know the age of the Universe? Doesn’t it sound bonkers that some evolved bipedal mammals, on a rock, spinning around space are able to determine the age of known existence around them. Surely there isn’t a cosmic clock that tells us the Universe is 13.8 billion years? I mean, the Earth is only 4.5 billion years old and humans have only been around for around 200,000 years, so how on Earth can we know the age of the Universe?! Well, the cosmic clock is real, and is imbedded in some clever, clever mathematics. Let’s get into it.

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Light-Years

A light year is the distance that light travels in a year.

This can be calculated using the given equation.

Remember: calculate 1 year in seconds before trying to determine how long a light year is. (1 year in seconds = 31,536,000s)

A light year is 9.5x10^15m

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Big Bang Theory

The Big Bang Theory states that all current and past matter in the Universe came into existence at the same time from a small point of energy that exploded with extreme force.

This occurred around 13.8 Billion years ago.

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Continuous and Line Spectra

All elements emit a unique light spectrum. Using spectroscopy and by visualising line spectra, we can see what elements distant stars and planets contain.

You need to be able to identify different elements from provided line spectra. The images show a continuous spectrum, absorption line spectrum and an emission line spectrum.

Key Points!

  • Light Years

    A light year is the distance that light travels in a year.

    Be able to calculate a light year in metres.

  • The Big Bang Theory

    The Big Bang Theory states that all current and past matter in the Universe came into existence at the same time from a small point of energy that exploded with extreme force.

    This occurred around 13.8 Billion years ago.

  • Light Spectra

    All elements emit a unique light spectrum.

    You need to be able to identify different elements from provided line spectra.

Any Questions?