QUANTUM PHYSICS LECTURE 1 REWIRING YOUR BRAIN IKSAN

QUANTUM PHYSICS LECTURE 1: REWIRING YOUR BRAIN IKSAN BUKHORI M. PHIL.

Textbook: TEXTBOOK ANDL. SYLLABUS 1. Richard Liboff - Introductory quantum mechanics. Longman Higher Education 2. Robert Eisberg, Robert Resnick - Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles-Wiley 3. Ramamurti Shankar - Principles of Quantum Mechanics, (Second Edition) -Springer 4. Stephen Gasiorowicz - Quantum Physics, 3 rd Edition-John Wiley and Sons

Grade Point: 85 – 100 : A GRADE POLICY 70 – 84 60 – 69 55 – 59 0 – 54 : B : C : D : E (GPA = 4) (GPA = 3) (GPA = 2) (GPA = 1) (GPA = 0) § The use of smartphone calculator in quizzes and exams is prohibited.

Grades: Grade = 10% Homeworks + 20% Quizzes + GRADEFinal POLICY § § § 30% Midterm Exam + 40% Final Exam + Extra Points Homeworks will be given in fairly regular basis. The average of homework grades contributes 10% of final grade. Homeworks are to be written on A 4 papers, otherwise they will not be graded. Homeworks must be submitted on time, on the scheduled day of the lecture. If you submit late, the penalty will be – 10·n points, where n is the total number of lateness made. There will be 2 quizzes. The average of quiz grades contributes 20% of final grade. Midterm and final exam schedule will be announced in time.

§ Extra points will be given if you solve a problem in front of the class. You will earn 1, 2, or 3 points. GRADE§POLICY Make up of quizzes and exams will be held within one week after the schedule of the respective quizzes and exams. § To maintain the integrity, the maximum score of a make up quiz or exam can be set to 90. Quantum Physics Homework 6 Rudi Bravo 009201700008 21 March 2021 No. 1. Answer: . . . . Heading of Homework Papers (Required)

§ Lectures will be held in the form of Power. Point presentations. § You are expected to write a note along the lectures to record LECTURE ACTIVITIES your own conclusions or materials which are not covered by the lecture slides. How to get good grades in this class? • Do the homeworks by yourself • Solve problems in front of the class • Take time to learn at home • Ask questions

§ Latest lecture slides will be uploaded to my blog LECTURE MATERIAL iksanbukhori@wordpress. com § You are responsible to read and understand the lecture slides. I am responsible to answer your questions. § Quizzes, midterm exam, and final exam will be open-cheat sheets. Be sure to have your own copy of lecture slides. You are not allowed to borrow or lend anything during quizzes or exams. § But: A homework can be submitted late without penalty if a scanned or photographed version of the homework is sent to iksan. bukhori@president. ac. id before the class begins.

There will be no remedial for any quizzes nor exams. EXTRA §ASSIGNMENTS § As replacement, you may submit a neat summary of your notes or collection of problems and solutions related to all topics covered up to that point in handwritten with A 4 paper § This extra assignment will not be announced beforehand has to be submitted one day after your quiz/exams paper is returned § The extra grade depends on the materials covered, how neat it is and how good your understanding of the materials actually is (Copying my slides or the book(s) will not do)

WHY QUANTUM PHYSICS IS UNSETTLING • Let’s say an electron has two independent properties, Colour and Hardness • These two properties are binary properties, i. e. an electron can be White OR Black and Soft OR Hard • Which means we can create a sorting box for these two properties H B In C W In H S

SOME NOTES • Colour and Hardness are persistent properties, i. e. B 0% In W C … C H H In H W 100% S … H S 100%

SOME NOTES • Colour and Hardness are independent B 50% Random C W … H B 50% H 50% Random H S W 50% … C W 50%

LET’S DO SOME EXPERIMENTS Experiment #1 Random C B? H B W … H S … C W? Prediction: W = 100% B = 0% W = 50% B = 50% WHAT. THE. HEL

TRYING TO BUILD COLOUR AND HARDNESS DETECTOR BH BS WH Random BH WS BS H THIS IS THE ESSENCE OF UNCERTAINTY PRINCIPLE H Random ? H B C WH S WS

LET’S PUSH THE EXPERIMENTS FURTHER • Let’s introduce a new apparatus Out H In H S

Experiment #2 H? H S? H W H S Prediction: H = 50% S = 50%

Experiment #3 B? C W? H H H S Prediction: B = 50% W = 50%

Experiment #4 B? C W? H W H S Prediction: B = 50% W = 50% 0% 100%

Experiment #5 B? C W? Prediction: H W H S B a r r i e r Output Down by 50% W = 100% 50%

WANT SOMETHING MORE DISTURBING? Question: Which route did the electron take? Which Path? H? No S? Both? No No Neither? No B? C H W H S W?

SO WHAT IS GOING ON? If the experiments are accurate and the arguments correct, the electrons are in fact doing something we have never dreamed of before and for which we do not at the moment have any words. Electrons have modes of moving or modes of being, which are unlike anything we have discussed thus far. This is also true of molecules, bacteria, and other macroscopic objects, though the effects are harder to detect. Physicists call such modes as being defined by superposition, which for now means “we have no clue what is going on”.

SO WHAT IS GOING ON? In the context of our previous experiments, an initially white electron inside the apparatus with all walls out is not hard, not soft, not both, and not neither, but is in a superposition of the states of being hard and soft. This is why we cannot meaningfully say that an electron has given definite values of color and hardness. This is not because our boxes are crude or because we are ignorant (though both may incidentally be true). There is a deeper reason: having a definite value for one property implies not having a definite value but instead being in a superposition of values for the other property. Every electron exits a particular box as having one value or the other for the measured property, but not every electron is in a state of one value or the other for that property. It can be in a superposition of the two values, with the probability that we subsequently measure it to have one value or the other depending on the details of the superposition. For instance, an electron that is white is in an equal superposition of being hard and soft, as the probability of measuring each value of hardness is equal.

THANK YOU SEE YOU NEXT WEEK