QuoteRef: feynRP_1963

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references e-f
what is truth
empirical truth
science as experiment
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scientific method
law of nature
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electromagnetic field
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skepticism about knowledge
quantum mechanics
Newtonian physics
limitations of formalism
infinity and infinitesimal
real numbers and floating point numbers
special relativity


Feynman, R.P., Leighton, R.B., Sands, M., The Feynman Lectures on Physics, mainly mechanics, radiation, and heat, 1, Reading, Massachusetts, Addison-Wesley Publishing, 1963. Google

Other Reference

for pages 22- see (QuoteRef: feynRP_1963x)
for chapters 37 and 38 see (QuoteRef: feynRP_1965)

1-1 ;;Quote: everything we know is an approximation to the complete truth about nature
1-1 ;;Quote: the defining principle of science is that experiment is the sole judge of scientific truth
1-2 ;;Quote: the atomic hypothesis is the main result of science: all things are made of atoms which move in perpetual motion, attract when a little apart, and repel if squeezed together
1-3 ;;Quote: if an apple is magnified to the size of the earth, its atoms are the size of the original apple
1-3 ;;Quote: a gas in a small box is like a room with a hundred tennis balls bouncing around and bombarding the walls
1-4 ;;Quote: in ice, the atoms vibrate in place; melting occurs when they shake themselves out of place; minimum vibration at absolute zero
1-4 ;;Quote: when water evaporates, the more energetic molecules leave and hence cool what remains; similarly, vapor to water increases the temperature, so blow on water to cool it
1-7 ;;Quote: carbon attracts oxygen much more strongly than carbon and much more strongly than oxygen attracts oxygen; so burning causes great commotion which heats things up
1-8 ;;Quote: key hypothesis: everything is made of atoms, everything that animals do atoms do; the laws of physics should explain everything
1-8+;;Quote: a pile of atoms that are not repetitious like a crystal or liquid might well be human
2-1 ;;Quote: the scientific method consists of observation, reason, and experiment
2-1 ;;Quote: fundamental physics is like the rules of the game of nature; can thus understand the world even though its application may be much too complicated
2-3 ;;Quote: the ultimate basis of interaction between atoms is electrical
2-3+;;Quote: balanced electrical charges do not attract at a distance; but at short scales, the charges rearrange and generate strong interactions
2-4 ;;Quote: electricity is a much stronger force than gravitation
2-4+;;Quote: if two grains of sand were 30 meters apart and all electrical forces were attractive, there would be three million tons of force between them
2-4 ;;Quote: although electrical force goes inversely as the distance squared, a shaking charge conveys influence much farther out
2-4+;;Quote: the electromagnetic field conveys the vibrations of electrical force like water conveys waves
2-4+;;Quote: in water, one cork can move another much further away by jiggling than by pushing; same with charges in an electromagnetic field
2-5 ;;Quote: the only difference between electromagnetic waves is the frequency of oscillation
2-6 ;;Quote: atoms are big because of the uncertainty principle; if electrons were in the nucleus one would know their location precisely and their momentum would be very large and uncertain
2-6 ;;Quote: if an atom were the size of a room, the nucleus would be a spec of dust; very nearly all of the weight of an atom is in the nucleus
2-7 ;;Quote: fundamental hypothesis of science: the sole test of the validity of any idea is experiment; we must formulate our ideas in terms of our actual experience
4-2 ;;Quote: we do not know what energy is; energy is just a calculated number that is always the same for a given system
5-1 ;;Quote: quantitative relationships are the heart of physics
5-1+;;Quote: only with quantitative observations can one arrive at quantitative relationships
5-1 ;;Quote: before Galileo, the study of motion was based on ideas and arguments; Galileo was skeptical; he measured how far a ball rolled in how long a time
5-1 ;;Quote: we probably can not define time; we measure it by the repetition of some apparently periodic event
6-10 ;;Quote: our most precise description of nature must be in terms of probabilities; the uncertainty principle
6-10+;;Quote: in a hydrogen atom, the uncertainty of the electron's position is as large as the atom itself; an electron is like a cloud representing its probability density
7-3 ;;Quote: Newton proved that Kepler's 2nd law of equal areas in equal times is a direct consequence of the idea that all forces are directed exactly toward the sun
7-5 ;;Quote: a physical law is wrong if it does not work in one place where it ought to
7-5+;;Quote: in 1656 Roemer measured the speed of light by measuring the discrepancies in the orbits of Jupiter's moons when Jupiter was close to earth and when it was far from earth
7-7 ;;Quote: the galaxy is not a ball because of angular momentum; it must contract mostly in a plane
7-7+;;Quote: gravity apparently goes forever inversely as the square of the distance; i.e., the gravitational force on a spherical shell is independent of its radius
7-9 ;;Quote: the theory of gravitation had an immense effect on science; here was a simple rule that governed the motion of the planets
7-10 ;;Quote: the ratio of electrical and gravitation force between two electrons is independent of distance; it is 1 divided by 4.17 x 10^42!
7-11 ;;Quote: mass or inertia is how hard it is to hold something which is going around in circle
7-11+;;Quote: because the force of gravity is proportional to mass, a small satellite inside a large one is perfectly balanced or weightless
8-2 ;;Quote: in science, we cannot define anything precisely; we have to agree that we are talking about roughly the same thing; avoids paralysis of thought
8-3 ;;Quote: in Zeno's argument there is an infinite number of steps but not an infinite amount of time; instead, a derivative concerns the ratio of infinitesimals
8-3+;;Quote: the scientific definition of speed is the ratio of infinitesimal distance over infinitesimal time as the time gets smaller and smaller; not known to the Greeks
10-9 ;;Quote: if an electrical charge is suddenly moved, its effect is delayed and the electromagnetic field contains the momentum; the sum of field momentum and particle momentum is conserved
10-9+;;Quote: an electromagnetic field is real because it can possess momentum and energy
11-6 ;;Quote: for three numbers to be a vector they must be associated with a coordinate system so that rotating the coordinate system rotates the vector
12-1 ;;Quote: Newton's laws: if we study the mass times the acceleration and call the product the force, we will find that forces have some simplicity and independent properties; e.g., gravity
12-5 ;;Quote: the coefficient of friction is an artifact; two pieces of pure copper will stick together because the atoms get "confused", and a glass tumbler will scratch a wetted glass plate
12-6 ;;Quote: for nonpolar molecules the electrical attraction at large distances varies inversely as the seventh power of the distance; dipolars have greater attraction
12-6+;;Quote: at close distances, atoms and molecules very strongly repel; it keeps us from falling through the floor
12-9 ;;Quote: principle of superposition of electrical fields: the total field due to all sources is the sum of the fields due to each source
14-3 ;;Quote: for a conservative force, the work done by moving an object does not depend on the path; i.e., kinetic energy plus potential energy is constant
14-3+;;Quote: all fundamental forces of nature appear to be conservative
15-1 ;;Quote: Newton first stated the principle of relativity: the motions of bodies in a given space are independent of uniform motion of the space in a straight line
15-5 ;;Quote: clocks move slower in a moving system; construct a clock by bouncing light perpendicular to the motion; to the stationary observer, the light follows a longer, zigzag path and the clock ticks are slower
15-5+;;Quote: if one clock behaved differently than another in a moving system, could distinguish the systems; hence all clocks behave the same
16-2 ;;Quote: just because an idea has held for a very long time does not make it true; for example, the theory of relativity overturned Newton's laws
16-2+;;Quote: every idea can be wrong
18-6 ;;Quote: Kepler's law about equal areas in equal times is the law of conservation of angular momentum when there is no torque, i.e., the force is radial
19-2 ;;Quote: Newton's laws approximate the actual quantum-mechanical laws of motion on a fine scale; Newton's laws fortunately become more accurate as the scale increases indefinitely

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