THE MODERN WORLD – WE OWE IT TO PHYSICS Michael Bass Emeritus Professor CREOL, The College of Optics and Photonics University of Central Florida MY DEBTS Outstanding students: At USC: M-J Soileau and S-T Wu AT CREOL: Alexandra Rapaport and T-Y Chung Outstanding Post-Docs/Colleagues: At USC: Eric Van Stryland At CREOL: Ying Chen and Scott Webster And many others! CREOL where I had the opportunity to do my research and to explore my interest in the Culture and History of Science. IN THE BEGINNING God said let there be light – God was the first physicist and an optics person !! Actually about 28,000 years ago someone made notches on a bone counting the lunar months – he/she was keeping time. 4236 BC – Egyptian calendar showing that the star Sirius rose next to the sun every 365 days. 1400 BC – first water clocks. This is critical break from measuring time by astronomy to measuring it by a mechanical device. ~1550 AD Nicolas Copernig (Copernicus) revises the calendar by assuming the earth goes around the sun – starts a revolution. WHERE AND HOW DID SCIENCE GET STARTED? Near 600 BC Thales of Miletus suggested that things may follow consistent principles that humans could figure out. No myths or Gods were required, just human intelligence. Pythagoras (580 to 490 BC) when he developed the Pythagorean theorem relating the lengths of the sides of right triangles. This simple mathematical formula is the first instance of theoretical physics. Logic- it was essential in a democracy (limited though it was) such as Athens. Logical thinking was essential to scientific inquiry. Euclid – plane geometry, conical sections, spherical geometry and rigor in proofs. Archimedes – levers, buoyancy and reflection of light. In ancient Greece by some very bright thinkers! ARISTOTLE’S COSMOLOGY – THE CELESTIAL ORBS With the earth at the center, 8 spheres carried all else. fixed stars 5 known planets moon sun The earth was a sphere since that was the perfect shape. With some perturbations known as epicycles by Ptolemy this worked quite well for nearly 2000 years. THE INDISPENSABLE INVENTION THE PRINTING PRESS 1041-1048 CHINA 1234 KOREA 1450 GERMANY – JOHANNES GUTTENBERG Invents a way to make moveable metal type to enable affordable books and widespread distribution. Leads to the Protestant movement and blossoming of science – puts ideas in the hands of the people. It was to the 15th century what the Internet is to the 21st. THE JULIAN CALENDAR BASED ON ARISTOTLE’S UNIVERSE WAS GETTING OUT OF SYNCH. This would embarrass the church. So in 1514 the Pope asked Copernicus to look into calendar reform. Copernicus did and discovered that Aristotle was wrong. The earth had to move around the sun. This was heretical even if it was correct. In 1543 he published his work “On the Revolution of the Celestial Orbs” and 2 months later he died. In 1582 the Gregorian (Copernican) calendar was adopted . His work was followed by Brahe, Kepler and Galileo all showing that humankind was not at the center of the universe. In fact the orbits were not even circles. Then came Newton!! ISAAC NEWTON (1643-1727) Together with Albert Einstein one of the two greatest scientists that ever lived. Except for the time wasted trying to perform alchemy and find the Philosopher’s Stone (~ 30 years) Newton was the Lucasian Professor of Mathematics at Trinity College at Cambridge. Invented Calculus (actually co-inventor with Liebnitz and a little with DesCartes). Laws of Motion. Applied inverse square law of gravity to derive planetary orbits. Invented the Newtonian telescope. Showed that white light was made of light of different colors. Observed Newton’s rings – an interference effect due to wave nature of light. Equally important was his demonstration of using fundamental principles to solve physics problems. This was the Newtonian synthesis. It was the critical tool needed to kick start the modern world. CONSERVATION LAWS AND THERMODYNAMICS There was a quantity called temperature that had to be defined to enable the discussion of heat. Newton’s law – if there is no external force acting on a body the quantity mass times velocity (momentum) does not change. Total mass (today we say total mass-energy) is conserved. After Nicholas Leonard Sadi Carnot in 1824 published one of the most important papers in history others realized that his most efficient engine was one in which entropy did not change. In all others it must increase. P isoth. adiab. adiab. isoth. V THE LAWS OF THERMODYNAMICS 0. YOU ARE ALLOWED TO PLAY - (THERE IS A QUANTITY CALLED TEMPERATURE.) 1. THE BEST YOU CAN DO IS BREAK EVEN – (MASS-ENERGY IS CONSERVED) 2. IF YOU PLAY LONG ENOUGH YOU ARE SURE TO LOSE – (IN A CLOSED SYSTEM UNDERGOING A THERMODYNAMIC PROCESS THE CHANGE IN ENTROPY CAN EITHER BE ZERO OR POSITIVE.) THE INDUSTRIAL REVOLUTION – SCORE 1 FOR PHYSICS The ideas just mentioned enabled inventors of steam engines, farm machines, factory machines, interchangeable parts, food processing techniques, transportation by ship and train, improved water supply and sanitation, the flush toilet and advances in construction to flourish. These to name a few. THE IMPACT Human population which from 1500 to 1700 had been pretty constant at about 425 M grew to about 1 B by 1800. There was: Better housing, cleaner water, better sanitation, clothing and cleanliness (people used soap – probably the most important medicine prior to antibiotics). There were abuses – child labor, slavery, unsafe working conditions and so on but improved transportation made it cheaper and people could leave places where life was harsh to try for something better. They came to the Americas and eventually this led to the United States. THE ELECTROMAGNETIC REVOLUTION During the industrial revolution another revolution was taking place. The physics of it began way back in Greece when people rubbed one thing against the other and found that they became attracted to each other. 2000 years later Coulomb, Franklin, and Biot and Savart, demonstrated critical properties of electricity and magnetism. The force laws The properties of charges MICHAEL FARADAY Then in 1831, an uneducated bookbinder’s assistant, Michael Faraday, performed incredibly crucial experiments demonstrating that you could turn mechanical motion into electric current and vice-versa. He had shown how to make an electric generator and an electric motor. He invented the concept of fields to describe his results since he didn’t have the math skills. Without Faraday there would be no modern world. MAXWELL, ELECTROMAGNETISM AND ELECTROMAGNETIC WAVES Without James Clerk Maxwell in 1861 at the age of 22 the electromagnetic revolution would have taken much longer to happen. His famous equations describe electromagnetic fields that result in electromagnetic waves that propagate at the speed of light. These give access to the whole q E electromagnetic spectrum. 0 This is probably what god said. B 0 E B t B 0 J 0 0 Without Maxwell there would be no modern world. E t THE ELECTROMAGNETIC REVOLUTION – SCORE 2 FOR PHYSICS To the industrial revolution add electricity to the factory and the home, safer street lighting, reduced fire risk, telegraphy, telephones, radio, television, radar, improved automotive electronics, improved aircraft, improved medical instrumentation and diagnostics, and so much more including greatly improved optics and spectroscopy. THE IMPACT In 1850 human population was about 1.2 B in 1950 it was 3.0 B. Another huge impact of physics on the modern world. Prior to this period almost everyone was born, lived and died within a 10 mile radius. Transportation and mass manufacturing made huge cities possible. THE PROBLEM The progress of science in the industrial revolution and the electromagnetic revolution was put to use in WW I and WW II and by some of the most evil dictators in history. That is the problem. Scientists may do their work but politicians, dictators and crackpots too often get to use it. THE QUANTUM MECHANICS REVOLUTION In the early 1900s there were Max Planck, Neils Bohr and Albert Einstein who quantized electromagnetic fields and atoms, and showed that Bohr’s transitions and Planck’s quantized energies led quite naturally to the “black body” distribution that Planck hypothesized. There had to be something to quantum mechanics! IT GETS CURIOUSER AND CURIOUSER Werner Heisenberg, Erwin Schrodinger, Wolfgang Pauli, Paul A. M. Dirac and many others fleshed out the mathematics and interpretations of this very strange subject. All you could know is the likelihood of something happening. You had to give up causality because in the quantum world, the world of the atom and smaller, things were statistical. And most distressing was the uncertainty principal: iℏ∂Ψ/∂t=-(ℏ2/2m)∂2Ψ/∂x2+V(x)Ψ px h SO WHAT DID QUANTUM MECHANICS DO? Besides nuclear weapons and nuclear power? Lasers, computers, solid state electronics, medical imaging technology (NMR and MRI), global positioning systems, more reliable aircraft and navigation systems, cell phones, the internet, electronic automotive ignition systems , LED lighting, solar energy systems, bio-medical instrumentation THE IMPACT Between 1950 and 2015 the world’s population went from 3 B to 7 B. Quantum mechanics contributed to this growth through the effects of the technologies indicated and will through the developing field of miniaturized and personalized technologies. It will play a role in leading to more efficient solar energy systems, higher temperature superconductors, continuing Moore’s Law and many other things we can’t even imagine just now. One area all three critical contributions of Physics can be used is to find ways to bring clean water and better waste disposal to all people. Water borne diseases are endemic and easy to prevent but hard to deal with in all societies. THE QUANTUM MECHANICS REVOLUTION – SCORE 3 FOR PHYSICS There may be more. ARE WE ALONE ? Is the earth the only rock in the universe that is aware of the universe? Whether it is yes or no, the answer to this question is the most awe inspiring humanity seeks. Hence the Search for Extra-Terrestrial Intelligence or SETI. Until now SETI has been underfunded and “under-technologied”! Except for the movie Contact and an occasional Nova program the public knows little about SETI. This is about to change. Yuri Milner, a multi billionaire has donated $100 M to SETI and in 2016 the effort will expand dramatically. THE NEW SETI Quantum mechanics has made possible new technologies that will allow a dramatic expansion of SETI in 2016 to scan over 100 M star systems for signals at 10 B radio frequencies. These are in the Milky Way and outside it. There will also be optical scanning to look for laser signaling. The data rate will be 10 Gbytes/sec so many supercomputers and distributed computers will be used to examine the data for signals. The Internet is critical. 2016 will be the start of a 10 year effort. THE TOOLS OF THE NEW SETI The new SETI will use : the 100 m Green Banks Telescope in West Virginia, the 64 m Parkes Telescope in New South Wales, Australia, and the 2.4 m Optical telescope at the Lick Observatory near San Diego, California. WE HAVE TO GET OUT OF HERE As you can see if nothing else happens (in 3 B years the Milky Way and Andromeda will collide) the sun will warm up and boil off of all the earth’s water in less than 3 B years. If humanity lasts long enough and is to survive it must spread out to other planets. Since we don’t yet know how to exceed c it will involve multi-generational, one way trips. PHYSICS, BIOLOGY, CHEMISTRY, ENGINEERING, MATERIALS SCIENCE AND PSYCHOLOGY ALL WILL HAVE TO HELP Contribute to longer human lifetimes. Maybe miniaturize humans. Greatly miniaturized and more efficient propulsion systems. Reliable quantum computing for data storage and access. Techniques to make humans and animals more efficient in use of resources (food and water) and in waste reprocessing. I doubt that warp drives or worm hole travel will actually happen but given time and creative minds something might happen to allow for travel nearer to c than we can now imagine. BEFORE GETTING OUT OF HERE Unlike any other species of any sort except microbes we have to survive long enough to accumulate the skills and wills to try to move on. It will be very expensive and psychologically difficult. None of us will be here when that time comes, if it ever does, but in the meanwhile we can contribute to the knowledge base that might help. MY CLASS If you found this sort of stuff interesting and would like more in depth discussion please sign up for my special topics class in the spring of 2016. It is called “The History of Physics, Cultural Connections and Other Issues” Thank you.