Cosmology Flashcards
What does the Big Bang theory state?
It states that about 13.8 billion years ago the universe expanded from a single, incredibly small point and is still expanding today.
How long did the expansion take in the Big Bang theory?
It happened in an unimaginably small time - one billionth of a trillionth of a quadrillionth of a second.
What evidence supports the Big Bang theory?
Cosmic microwave background radiation (CMBR) and red-shift.
What is cosmic microwave background radiation (CMBR)?
It is the energy leftover from the original explosion.
What does red-shift show?
It shows that the universe is expanding.
What is cosmic microwave background radiation (CMBR)?
CMBR is heat energy ‘left over’ from the Big Bang during the initial hot explosion.
What is the frequency of CMBR?
It has a very low frequency.
Where is CMBR emitted from?
It is emitted from all parts of the universe, in all directions.
Why does CMBR have a lower frequency?
As the universe expands and cools down, the background also cools, causing the CMB radiation to have a lower frequency.
Why is CMBR strong evidence for the Big Bang theory?
It is ‘leftover’ radiation from the Big Bang, which supports the idea of an initial hot explosion.
What is the Doppler effect?
The Doppler effect is the phenomenon where waves emitted from moving objects show a change in frequency (and wavelength) as they move.
Why does the pitch of an ambulance siren change?
The pitch changes due to the Doppler effect as the ambulance moves past you.
What happens to the light emitted from a star moving further away?
As a star moves further away, the light it emits will have a lower frequency.
What does lower frequency of light correspond to?
Lower frequencies of light correspond to the red end of the visible spectrum, called red-shift.
What does red-shift tell us about stars?
The further away a star is, showing that stars are moving away from us.
What evidence does red-shift provide about the universe?
Red-shift suggests that the universe is expanding, as stars emit more light in the red part of the spectrum the further away they are.
