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