The Universe… and Everything Else

1. The Universe… and Everything Else

2. Part One Cosmology

3. Definition: Cosmology (Cosmos = The heavens, ology= The study of) The study of the origin, evolution, structure and future of the universe.

4. Aristotle (384-322 BC) Philosopher and Mathematician The Earth is a sphere. It is surrounded by concentric celestial spheres. Stars are attached to these spheres and the spheres rotate around the Earth

6. Ptolemy (2nd Century CE) Mathematician, Astronomer and Astrologer Planets move around the Earth, but also on their own epicycles. Ptolemy also thought that some objects might orbit the sun. This system was incorrect, but it allowed for precise calculations of where the planets would appear in the sky.

7. A planet in orbit around the Earth and on an epicycle of its own.

8. Tycho Brahe (1546-1601) Astronomer and Alchemist Believed that the planets orbited the sun, but that the sun (and planets orbiting it) orbited the Earth.

9. The Earth (middle) is orbited by the moon, and also the sun (with other planets orbiting the sun). Note the celestial spheres on the outside where the stars are attached.

10. Nicolaus Copernicus (1473-1543) Astronomer Copernicus was the first to develop a comprehensive sun-centered model of the solar system. He believed that all of the planets (including the Earth) were heliocentric.

11. Circular orbits around the sun. Notice that Copernicus still had a celestial sphere in his model

12. Johannes Kepler (1571-1630) Mathematician, Astronomer, and Astrologer Kepler used physics and mathematics to improve Copernicus’s model. Kepler realized that the force of gravity between the planets and the sun forced planets into elliptical orbits.

13. Planets get slower as they move away from the sun, but then speed up on the way back. This is an effect of gravity and it produces elliptical orbits.

14. Isaac Newton (1642-1727) Physicist and Mathematician Newton developed a new form of mathematics that helped to explain how gravity works. His ideas proved that Kepler was right. What Kepler observed, Newton proved.

15. Newton worked out his famous laws of physics while his university was closed due to the Black Plague. Although Einstein later found that Newton’s laws were incomplete, they are good enough for most calculations and are still used today.

16. Albert Einstein (1917) Theoretical Physicist Einstein built on Newton’s work. He came up with a new theory about how gravity works. He said that large masses “curved” space which meant that large objects would fall towards each other. Although his equations could be used to show that the universe was probably expanding, he first chose to believe that the universe was stable (not expanding).

17. The Earth orbiting the sun due to the curvature of space created by the sun’s mass.

18. George Lemaitre (1927-1931) Catholic Priest, Astronomer, and Physicist Lemaitre used Einstein’s equations to prove that the universe was expanding. In 1931 he published a paper on the “Primeval Atom”. This later became known as the “Big Bang” theory.

20. Edwin Hubble (1920’s and 30’s) Astronomer Hubble discovered that light from neighboring object in space had a “Red Shift” which meant they were moving farther apart. Objects far away were moving faster and objects closer were moving slower. This was the first evidence that the Big Bang theory might be accurate and that the universe was small in the past and is expanding today.

21. Light from an object moving closer has a shorter wavelength (blue shift). Light from and object moving away has a longer wavelength (red shift).

22. Part Two The Big Bang

23. During the first picosecond (0.000000000001s) of the Big Bang, the universe began to expand from a small point called a singularity (similar to a massive black hole). Because things were so compressed, only energy existed.

24. At first their was only one force holding everything together, but as the universe expanded the temperature cooled and this force broke into the four fundamental forces that scientists are aware of today.

25. Before the end of the first full second, the universe has cooled down to a point where energy had began to change to matter. The first form of matter was probably quarks which are the building blocks of larger pieces of matter.

26. Some quarks came together to form the first protons. Hydrogen was the first (and still is the most abundant) element in the universe because it has the simplest nucleus (one proton).

27. Sometime before the first hour was finished, helium also was formed. Hydrogen atoms came together in early stars to form this element, the second most abundant in the universe. The process is called fusion. Even today, nearly 100% of the mass in the universe is hydrogen or helium

28. After about 1 million years, electrons have formed and are joining with protons and neutrons to form stable atoms.

29. At this point, the universe has also cooled down enough so that energy is not interacting (or changing into) matter at anywhere near the rate at which it did in the beginning. The amount of matter formed in the universe gives it shape. Too much matter, and the universe would curve in on itself, to little and it would form a shape like a saddle and continue forever. For reasons we can’t yet fully understand there was just enough matter to form a “flat universe”.

31. After about 100 million years the stars begin to shine, and at 600 million years stars have begun to come together to form the first galaxies. Our own sun was not formed until about 9.1 billion years after the beginning.

32. Most scientists believe that it has been about 13.7 billion years since the Big Bang began. Humans, the Earth, and even the sun have only existed for a very small sliver of those 13.7 billion years.

33. Consequences of the Big Bang

34. Scientists believe that the Universe is infinite or so big that we can consider it to be infinite. The stars we see at night are only a small fraction of the universe. Most of the stars are so far away that their light hasn’t made it to Earth yet. Because the Universe is expanding, we may never see them.

35. Thought Experiment

36. The possibility of life existing elsewhere in the universe is extremely high. In fact, the universe is so big that there are probably copies (repeats) of our own Earth or even of you. The problem is that the universe is so large that we may never see other life forms even though the likelihood of their existence is extremely high.

37. Will it end? How? As the universe continues to grow, we should also ask another question: How does it all end? Many scientists refer to the end of the universe as “Heat Death”.

38. The Heat Death theory states that as the universe expands, matter will cool down and begin to decay. Billions of years from now, even protons and neutrons will begin to break down. Even black holes will dissipate and fall apart.

39. As the universe expands matter and energy will spread out so much that the chances of matter bumping into each other will become increasingly unlikely. Without these interactions, the universe will become an increasingly dull place to the point where all action stops. The temperature will drop to a level almost at absolute zero.