Welcome to Physics 43!

Transcription

1 Welcome to Physics 43!

2 Classical Mechanics! Study of the motion of objects and mechanical systems that are large relative to atoms and move at speeds much slower than the speed of light.

3 You can t get to Modern Physics without doing Classical Physics! The fundamental laws and principles of Classical Physics are the basis Modern Physics.

4 Some Physical Models of the Universe A Brief History of Physics

5 Physics seeks a single theory of Everything. Bubble Universes Superstrings Theory of Everything (TOE)

6

7 Let no one unversed in geometry enter here. The Universe is made of pure mathematical ideas the Platonic Solids. Plato believed that the stars, planets, Sun and Moon move round the Earth in crystalline spheres.

8 Earth and the universe were seen as constructed out of five basic elements: earth, water, air, fire, and ether. The natural place of the motionless Earth was at the center of that universe. The stars in the heavens were made up of an indestructible substance called ether (aether) and were considered as eternal and unchanging. The laws of nature of the Earth were different from those of the Heavens.

9 The Sun and the planets would revolve in small circles whose centers revolve in large circles about the Earth ("epicycles") which is at rest and at the center of the Universe.

10 From our perspective, the sun and stars appear to orbit us!

11 Ptolemy's geocentric system, adopted by the Roman Catholic Church, dominated western thought until the time of Copernicus, 14 centuries later..

12 5 th -15 th Centuries

13 European Enlightenment Renaissance 14 th & 15 th Century The Vitruvian Man 1490

14 Copernicus put the Sun at the center of the solar system with the Earth orbiting around the Sun, thus proposing a heliocentric cosmology. Like Aristotle and Ptolemy, Copernicus retained the conventional idea that the planets moved in perfectly circular orbits and continued to believe that the stars were fixed and unchanging.

15 REVOLUTION!

16 I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it.

17 Heliocentric Heretics

18 Rome, Campo de'fiori: The monument to Giordano Bruno, burnt at the stake here.

19 Based on observational data he derived three laws of planetary motion that put the sun at he center of the universe with elliptical orbits.

20 Isaac Newton ( ) Using his Calculus, Newton derives Kepler s three laws of planetary motion from his own three laws of motion and his Universal Law of Gravity. Newton is the man of the millennium. In Principia (1687 ) Newton Invented Calculus 3 Laws of Motion Universal Law of Gravity

21 NOT ONLY is the Earth not immobile! The Earth Moves through Solar System at 30Km/sec!!!

22 Milky Way Galaxy At the turn of the 20 th century we did not know that there were other galaxies in the Universe!!! Orbital Speed of Solar System: 220 km/s Orbital Period: 225 Million Years

23 Gas Particles are in constant RANDOM motion Particles have different speeds Pressure is given by the momentum transferred by particles colliding Average KE of each particle is ~ T

24 2nd Law of Thermo Heat flows spontaneously from a substance at a higher temperature to a substance at a lower temperature and does not flow spontaneously in the reverse direction. Heat flows from hot to cold. Alternative: Irreversible processes must have an increase in Entropy; Reversible processes have no change in Entropy. Entropy is a measure of disorder in a system

25 Conservation of Energy Energy can neither be created nor destroyed. It may change in form or be transferred from one system to another. The total amount of energy in the Universe is constant and can never change. E i = E f Except for VERY brief amounts of time according to the Heisenberg Uncertainty Principle.

26 1860: E&M was Solved! (Vector Form)

27 James Clerk Maxwell 1860s Light is wave. The medium is the Ether. 1 8 c= = 3.0x10 m/ s με 0 o

28 What is the World Made of?

29 Why a discrete spectrum? Why THIS spectrum?

30 Why this shape? Why the drop?

31 Classical vs Modern Laws of Physics are deterministic. Space and time are absolute. Particles are Localized in Space and have mass and momentum. Waves are non-localized in space and do not have mass or momentum. Superposition: Two particles cannot occupy the same space at the same time! But Waves can! Waves add in space and show interference. Laws of Physics are statistical. Space and time are relative. The speed of light is absolute. Particles are wave-like Waves are particle-like

32 Modern Physics: Quantum Physics & Relativity

33 Unsolved Mysteries of 1900 s that gave birth to Modern Physics Where is the ether? Is light particle or wave? What is matter made of? How and why do atoms radiate discrete spectra? Are nebulae within our galaxy or are they other galaxies? Is space & time finite? Infinite?

34 Born 1879

35 Galilean Relativity The force on a moving charge depends on the Frame. Charge Rest Frame (moving with charge) Wire Rest Frame (moving with wire) F = 0 F = qvbsinθ Einstein realized this inconsistency and could have chosen either: Keep Maxwell's Laws of Electromagnetism, and abandon Galileo's Spacetime or, keep Galileo's Spacetime, and abandon the Maxwell Laws.

36 Newton s Principia in Galilean Relativity Space and Time are ABSOLUTE! Velocities add: V= U +V' V = 25m/s U = 20 m/s V = 45m/s

37 Time is Relative! Space is Relative! Only the SPEED OF LIGHT is Absolute!

38 Lorentz Contraction in Wire Moving charges in the wire cause a Lorentz contraction in the distance between the moving charges in the wire so that from the rest frame of the charge outside the wire (or at rest in the wire) the moving charges bunch up and thus give a net charge to the wire.

39 Eisntein Saves Maxwell! The force on a moving charge does NOT depend on the Frame. Charge Rest Frame (moving with charge) Wire Rest Frame (moving with wire) F = qvbsinθ F = kqq 1 2 / r 2 From the rest frame of the charge, the wire is charged and it feels a Coulomb force. The forces in each frame are equal though they are due to different causes!

40 On the Electrodynamics of Moving Bodies 1905

41 Energy is Converted into Mass E = mc 2

42 Fission Heavy elements FISSION into lighter elements, releasing energy in the process by E = Δmc 2, where Δm is the difference in mass between the parent and products. ~ 25 MeV is released in this reaction Most of the Energy is released in the form of Kinetic Energy (heat).

43 Nuclear Weapons

44 Albert Einstein 1916 Mass warps space-time. The Field Equation:

45 Evolution of Life in the Universe

46 Cepheids Andromeda Galaxy Hubble V = H o d

47 Space and Time were created in the Big Bang!

48

49 The Quantum Gang

50 Particles!

51

52

53 The Universe is made of Regular Matter: 5% Dark Matter: 25% Dark Energy: 70%

54 Dark Energy: Accelerating the Universe toward the Future

55 Future Evolution?

56 Quantum Entanglement Quantum Computing The Qubit At the heart of the realm of quantum computation is the qubit. The quantum bit, by analogy with the binary digit, the bit, used by everyday computers, the qubit is the quantum computer's unit of currency. Instead of being in a 1 or zero state, a qubit can be in a superposition of both states.

57 Quantum Teleportation??

58 Black Holes & Worm Holes

59 LISA Gravity Waves

60 Parallel Universes Multiverse

61 String Theory

62 Quantum Quackery?

63 The Final Frontier: Consciousness Each caged electron is a qubit in a nanoscale quantum dot. We have a billion billion of them enslaved by coherent near electromagnetic brain fields of low frequency. This forms a mind-brain hologram. There is direct back-reaction of the coherent phased array of single electron dipoles on their mental pilot landscape field. This generates our inner conscious experience. - Jack Sarfatti A Quantum Model of Consciousness

64