The Origin of the Universe Flashcards
The universe seems to be ____
The universe seems to be EXPANDING
How can we tell the universe is expanding?
All its galaxies seem to be moving away from each other
What evidence do we have that galaxies are moving away from each other?
Red-shift
Explain red-shift and how it provides evidence of the universe expanding
- Different chemical elements ABSORB different FREQUENCIES of light
- Each element produces a SPECIFIC PATTERN of DARK LINES at the frequencies that it ABSORBS in the visible spectrum
- When we look at light from DISTANT galaxies we can see the SAME PATTERNS but at slightly LOWER frequencies than they should be - they’re shifted towards the RED END of the spectrum. This is called red-shift.
- The lower frequencies are caused by the Doppler effect
Describe the bit about frequencies of chemical elements in red-shift
- Different chemical elements ABSORB different FREQUENCIES of light
- Each element produces a SPECIFIC PATTERN of DARK LINES at the frequencies that it ABSORBS in the visible spectrum
Explain the basic bit of red-shift
- When we look at light from DISTANT galaxies we can see the SAME PATTERNS of light absorption but at slightly LOWER frequencies than they should be - they’re shifted towards the RED END of the spectrum. This is called red-shift.
What happens to the waves emitted by an object when it is moving away from or towards you, compared to when it is stationary? (2)
The WAVELENGTHS and FREQUENCIES of the waves seem different
What will the wavelength and frequency of a source moving TOWARDS you sound like compared to when it is stationary?
The frequency will seem HIGHER
Wavelength will seem SHORTER
What will the wavelength and frequency of a source moving AWAY from you sound like compared to when it is stationary?
The frequency will seem LOWER
Wavelength will seem LONGER
So to recap
Towards = ___ and ___
Away = ___ and ___
Towards = HIGHER and SHORTER (‘h’s)
Away = LOWER and LONGER (‘l’s)
What is the phenomenon when the WAVELENGTHS and FREQUENCIES of the waves seem different when an object emitting waves is moving towards you and away from you called?
The Doppler effect
What kind of wave/ waves does the Doppler effect happen to?
Longitudinal AND transverse
What do measurements of the red-shift that ALL GALAXIES suggest? What does this provide evidence for?
That ALL galaxies are MOVING AWAY from us very quickly, and it’s the same result in EVERY DIRECTION you look in.
Evidence that the whole universe is expanding
What’s the relationship between how far a galaxy is from us and how fast they are moving away from us?
The FURTHER a galaxy is from us the FASTER it is moving away
Why does the universe’s apparent expansion (aka red-shift) provide evidence for the Big Bang theory?
Something had to have caused this expansion to start - which was probably a big explosion
What is the ‘Big Bang theory’?
All the matter in the universe must have been compressed into a VERY SMALL SPACE. Then it exploded from that SINGULARITY and started expanding
The expansion is ___ ____ .
The expansion is STILL ONGOING
What can we use the universe’s current rate of expansion to do?
Estimate the universe’s age
How long ago do we think the Big Bang happened?
14 billion years ago
What does the ‘Steady State’ theory say?
That the universe has ALWAYS existed as it is NOW, and it ALWAYS WILL do.
What is the ‘Steady State’ theory based on?
The idea that the universe appears pretty much the SAME EVERYWHERE
How does the Steady State theory explain the apparent expansion of the universe?
By suggesting that matter is being CREATED in the spaces as the universe expands
What is another piece of evidence for the Big Bang theory?
Cosmic microwave background radiation (CMBR) - the radiation that is found everywhere in the universe at pretty much the same frequency - what would have been released when the singularity exploded
What can the Steady State theory not explain?
Cosmic microwave background radiation (CMBR)
Which is the only theory that can explain CMBR?
The Big Bang theory
There’s ____ microwave radiation from ____ ____ .
There’s UNIFORM microwave radiation from ALL DIRECTIONS .
What is cosmic microwave background radiation (CMBR)?
Low frequency electromagnetic radiation that has been detected coming from ALL PARTS of the universe
Explain where CMBR came from
Just after the Big Bang when the universe was still EXTREMELY HOT, everything in the universe emitted very HIGH FREQUENCY RADIATION.
As the universe EXPANDED it has COOLED, and this radiation had dropped in frequency and is now seen as MICROWAVE RADIATION
What are the 2 main reasons some astronomers believe in the Steady State theory?
- Say EVIDENCE just points that way
2. Don’t want to change their minds - would mean admitting they were WRONG in the first place
What can the Big Bang not explain?
- The Big Bang theory predicts that the universe;s expansion should be SLOWING DOWN - but as far as we can tell it’s actually SPEEDING UP
- What CAUSED the explosion
- What the CONDITIONS were like before the explosion (or if there was a ‘before’)
What is the most probable future of the Big Bang theory? Why?
It will be adapted for its weaknesses NOT dumped - it explains so much so well
