3Age of the Universe Rocks on Earth Oldest stars Universe must be older Rocks on Earth4.2 billion yearsOldest stars10-12 billion yearsUniverse must be olderEstimate backwards13.8 billion years
4When you’re on a fast-spinning merry-go-round (like on a playground), why do you feel like you’re going to fly off?What is the evidence for dark matter?How do scientists know dark matter can’t be made of “ordinary” matter particles such as protons and neutrons?Prior to the late 1990’s, how did most cosmologists think the universe would end? Why did they think that?What is the evidence for dark energy?How much of the universe does dark energy make up? How much does dark matter make up?
5The Theories There are 3 major theories for how the universe will end. The Big CrunchThe Big ChillThe Big Rip
6The Big Crunch (“closed” universe) There is enough matter in the universe to slow its expansiongravity takes over.Gravity will then pull everything back together into one single point again.Without dark matter, this theory is not possible.Dark matter
7Dark EnergyIn the 1990’s scientists “discovered” a new force in the universe: Dark Energy.Dark energy is the opposite of gravity.Gravity pulls things together and dark energy pulls things apart.If the Big Crunch or Big Chill are correct we should see the expansion of the universe slowing… but it appears to be speeding up…
8The Big Rip (“open” universe) As the universe becomes more spread out dark energy has more power.This theory states that the universe will expand at a faster and faster ratedark energy will overpower gravityuniverse will be pulled apart (even atoms will be pulled to pieces)Runaway Universe (Start at 3:30ish)
11The Big Chill (“flat” universe) Assumes that there is not enough matter to stop the universes expansion (gravity isn’t strong enough)The galaxies will continue to drift apart (moving more and more slowly)the stars will use up all of the universes hydrogen (can’t form new stars)Universe will become cold and dark.