Wednesday, May 27, 2020

Science Matters by Robert M. Hazen and James Trefil

A very-well written survey.
Chapter 2 Energy
        Energy is conserved.
        Energy goes from more useful to less useful forms.
        Work is force times distance.
        Energy is the ability to do work.
        A boulder at the top of a cliff has potential energy as does gasoline.
        A speeding car has kinetic energy. Heat is a kind of kinetic energy, of atoms in motion.
        Electrical current, visible light, sound, mass, food, etc. have energy.
        Energy can be moved from one place to another.
        Heat conduction e.g. spoon in hot soup, molecules colliding. Convection, e.g. heated water moving up, replacing cooler water; the heat is carried. Radiation, e.g. hand near fire.
        Temperature is relative. Heat and temperature are different. Heat is the amount of energy.

Chapter 3 Electricity and Magnetism
        Electricity and magnetism are two aspects of the same force.
        Electrons are stripped from hair when combed.
        Plus attracts minus in chemical bonds, holding materials together. Electrons in shoes repel electrons in floor so we don't fall through.
        There are no isolated magnetic poles. Every time an electric charge moves a magnetic field is     created, and every time a magnetic field varies an electric field is created.
         Electric motors convert electricity into magnetic fields which cause useful rotary motion. A
battery can make a current flow through a wire loop. The current generates a magnetic field.            Putting the loop between two poles of a magnetic will cause it to rotate until the N of the loop's magnetic field gets to the S of the magnet. Alternating current of the right frequency cause the loop to keep rotating and driving a shaft or something useful. Generators reverse this process. converting mechanical energy to electrical.
         Maxwell realized that this duo of electric and magnetic fields cause radiation at the speed of light. Our eyes perceive a minuscule fraction of the electromagnetic spectrum. Radio waves have long wavelengths. Am radio like dimming a flashlight. FM like changing its color.
         Microwaves for communication, cooking, and radar.       
         Infrared is absorbed by the atmosphere. used for remote controls.
         X-rays and gamma rays, the most energetic. 

Chapter 4 The Atom
Chapter 5 The World of the Quantum
         We see by bouncing light off objects. If the objects are very small this inspection changes them. This is the uncertainty principle. We describe locations with probabilities because of this uncertainty..
         Quantum entanglement shows that quantum mechanics is not a local theory. It can be used for teleportation. The photon is recreated not transferred.
         Quantum computing is exponentially more powerful because qubits are in many states at once.

Chapter 6 Chemical Bonding
          Chemistry is the science of electrons and their interactions. Three kinds of bonds, ionic, covalent, and metallic. Filled electron shells are more stable.In an ionic bond one atom gives up an electron while another acquires it. Quartz combines oxygen and silicon. Metals have shells with a few excess electrons. Outer electrons are shared by all atoms in the system. In a covalent bond atoms share electrons to fill shells. The covalent bond is the basis for all life as in carbon-carbon bonds. The hydrogen bond involves a positive proton from shifting its electron to another atom which can attract other atoms. Water has this feature.
           Materials with ionic bonds make good insulators. The electrons are tightly bound. Materials in which electrons are loosely connected as in metals make good conductors. Covalent compounds of carbon-carbon bonds are almost as good insulators as ionic bonded ones. A semiconductor like silicon is intermediate. A slight impurity such as phosphorus has one more electron than silicon so it makes silicon a better conductor, called an n-type. Replacing a bit of silicon with aluminum with one fewer electron make a p-type semiconductor.
           The simplest semiconductor device is the diode formed from an n-type layer and a p-type layer. When first made the electrons from the n-type diffuse across to the p-type filling the holes so a border region between the layers is neutral. Applying voltage will cause current to flow in one direction only, the electrons can flow away from and not toward other elections. This rectifies alternating current making it direct. In solar energy systems the sun can provided the energy to move electrons from n to p.
           Transistors can be either pnp or npn layers.

Chapter 7 Atomic Architecture
Chapter 8 Nuclear Physics
Chapter 9 The Fundamental Structure of Matter
Chapter 10 Astronomy
Chapter 11 The Cosmos

Chapter 12 Relativity
            Every observer sees the same laws of nature. Different observers give different descriptions of the same event. In a car a book that falls straight down looks different to an outside observer. The speed of light is constant which violates our intuition. Einstein realized that if a streetcar moved at the speed of light away from a clock it would as if the clock had stopped. His pocket watch would remain the same. Consider a light clock in which a beam of light is sent upwards to a mirror and reflected back. Each time it returns is a tick. Now let another similar clock move away. The light as seen from the original position moves along a diagonal to nit the mirror in its new position and moves in a diagonal downward on the return (from the point of view of the stationary observer. Since the speed of light is constant and the distance is longer the tick must take longer as compared to the stationary clock so the moving clock runs slower. This is supported by experiment.
            For general relativity imagine being in a spaceship accelerating at the equivalent of earth's gravity. A dropped ball would appear to fall to the floor exactly as on earth. Looking at the spaceship from outside we would that the floor had accelerated upward to the stationary ball. Acceleration and gravity are equivalent. Gravity is an effect of our frame of reference. Stretch plastic over a frame. Rolling a light ball would cause it to go in a straight line. But a heavy ball would warp the plastic. Now a light ball would go closer to the heavy one because the space is deformed. Their is no force but a change in space.
           

Chapter 13 The Restless Earth

Chapter 14 The Earth Cycles
            Three basic types of rock: igneous, sedimentary, metamorphic. In the beginning all rocks were igneous -- fire-formed. Today igneous rocks are produced by volcanoes. Magma is the molten form of rock. Some cool deep underground. Sometimes they are lifted up like Mount Rushmore.Wind and rain break off pieces which form sediments, layer upon layer of igneous rock fragments. The accumulation of sediment may bury beach sand deep underground to form sandstone which get lifted up and weathered and so on. Plants die and form layers of coal. Organisms die and form limestone. Shale is made from silt and clay. Rocks that have been changed since they first formed are called metamorphic

Chapter 15 The Ladder of Life
Chapter 16 The Code of Life
Chapter 17 Biotechnology
Chapter 18 Evolution
Chapter 19 Ecosystems
Epilogue

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