12.1 - Explaining the Early Universe. Flashcards
Fun facts about the light:
- Light travels incredibly fast: about 1 000 000 000 km/h
- It takes light about 8 minutes to reach the Earth from the Sun.
- Light years are used to discuss the very large distances between stars and galaxies.
Fun facts about the universe:
- Imagine it as a sphere about 96 billion light years in diameter.
- Our galaxy, the Milky Way, is about 100 000 light-years across.
Explain the Big Bang theory.
The universe is expanding in every direction, and if we ‘rewind the clock’ it would have everything starting from a single point approximately 13.7 billion years ago. All the matter that makes up the universe started as a singularity. Inflation caused the universe to expand and has continued to expand ever since. It’s expanding faster due to a mysterious force we call “dark energy.”
Summary of Evidence for the Big Bang?
- Galaxies spread across the universe as if from a single point of origin.
- The cosmic microwave background radiation.
Explain how Galaxies spread across the universe as if from a single point of origin.
Edwin Hubble observed that galaxies are spreading apart. If you ‘rewind’ the universe, everything would start at the same place. More distant galaxies are also moving away from each other more quickly than closer galaxies.
What is Cosmic Microwave Background Radiation?
Everywhere we look in space; there is an almost perfectly uniform background ‘light’
It is the cooled remains of the first light that could ever travel freely throughout the Universe.
How might the universe end?
- The Oscillating Theory
- The Big Freeze (heat death)
- The Big Rip
What is The Oscillating Theory?
The Oscillating Theory is Eventually, the force of gravity between galaxies MAY slow down and then reverse the expansion of the universe that started during the big bang. MAY result in all matter returning to a single point in a Big Crunch, which MAY lead to another big bang!
What is The Big Freeze (heat death)?
The Big Freeze is when the universe continues to expand with galaxies spreading further and further apart.
Eventually, over trillions of years, all stars will burn out, and the universe will become a cold, dark place for eternity.
What is The Big Rip?
The Big Rip is when the matter in the universe spreads out at a faster rate due to dark energy.
Eventually, all matter will move so fast that even atoms will be torn apart, turning everything into energy again and perhaps triggering a new big bang.
What is The Nebular Hypothesis?
Suggests that our star and solar system were formed 4.5 billion years ago from a nebula. This nebula was likely leftovers of one or more dead stars that exploded or collided and left the chemical building blocks of our solar system floating in space. Gravity eventually pulled the gases together in clumps forming MOST objects in our solar system.
The quote “we are stardust” is more than just a cute expression. Explain in as much detail as possible how this expression is tied to the formation of our solar system.
Before our solar system formed a high-mass star would have lived its life and ended in a supernova, creating all of the materials needed to form our solar system. Over time gravity pulled the dust and gas into clumps. The most giant clump was located in the centre of our solar system and formed the Sun. Smaller clumps formed the planets and other materials like asteroids and comets.
A star just outside is the closest star to our solar system. it’s classified as a red dwarf. Describe at least three differences between the star and a star like our Sun
differences:
i) Red dwarfs are low-mass stars smaller than intermediate-mass stars like the Sun. They are typically less than half the size of our Sun.
ii) Red dwarf stars can last billions and trillions of years. The sun is 10 billion years.
iii) When our Sun runs out of fuel it will expand and grow into a red giant, a process that will not occur for red dwarf stars.
A star just outside is the closest star to our solar system. It’s classified as a red dwarf. Describe at least three similarities between the star and a star like our Sun
similarities:
i) All stars are made primarily of hydrogen and helium, including red dwarf stars and intermediate-mass stars.
ii) Both stars undergo nuclear fusion at their core which is what causes them to release radiation as light and heat
iii) Both intermediate and low-mass red dwarf stars will eventually end up as smaller white dwarf stars.
