For the Love of Physics Quotes

“What counts, I found, is not what you cover, but what you uncover. Covering subjects in a class can be a boring exercise, and students feel it. Uncovering the laws of physics and making them see through the equations, on the other hand, demonstrates the process of discovery, with all its newness and excitement, and students love being part of it.”
― Walter Lewin, For the Love of Physics

“My purpose in the classroom, and the main reason I’ve written this book, is to translate the truly astounding, groundbreaking, sometimes even revolutionary discoveries of my fellow physicists into concepts and language intelligent, curious laypeople can really get hold of—to make a bridge between the world of professional scientists and your world. Too many of us seem to prefer talking only to our peers and make it awfully difficult for most people—even those who really want to understand science—to enter our world.”
― Walter Lewin, For the Love of Physics

“why on earth should you generate current in that coil? It wasn’t clear at first what the importance of this discovery was. Soon afterward, the story goes, a dubious politician asked Faraday if his discovery had any practical value, and Faraday is supposed to have responded,”
― Walter Lewin, For the Love of Physics

“We don’t need to understand why a rainbow or fogbow or glassbow is formed in order to appreciate its beauty, of course, but understanding the physics of rainbows does give us a new set of eyes (I call this the beauty of knowledge).”
― Walter Lewin, For the Love of Physics

“of glass and put a magnet underneath, get ready for some remarkable results—a lot more interesting”
― Walter Lewin, For the Love of Physics

“One way to think of architecture and construction engineering, then, is that they are the arts of battling the downward force to a standstill. We may think of certain feathery skyscrapers as having escaped gravity. They’ve done no such thing—they’ve taken the battle literally to new heights. If you think about it for a little while, you’ll see that the stalemate is only temporary. Building materials corrode, weaken, and decay, while the forces of our natural world are relentless. It’s only a matter of time.”
― Walter Lewin, For the Love of Physics

“Like most stars, the really massive ones begin by burning hydrogen and creating helium. Stars are powered by nuclear energy—not fission, but fusion: four hydrogen nuclei (protons) are fused together into a helium nucleus at extremely high temperatures, and this produces heat. When these stars run out of hydrogen, their cores shrink (because of the gravitational pull), which raises the temperature high enough that they can start fusing helium to carbon. For stars with masses more than about ten times the mass of the Sun, after carbon burning they go through oxygen burning, neon burning, silicon burning, and ultimately form an iron core. After each burning cycle the core shrinks, its temperature increases, and the next cycle starts. Each cycle produces less energy than the previous cycle and each cycle is shorter than the previous one. As an example (depending on the exact mass of the star), the hydrogen-burning cycle may last 10 million years at a temperature of about 35 million kelvin, but the last cycle, the silicon cycle, may only last a few days at a temperature of about 3 billion kelvin! During each cycle the stars burn most of the products of the previous cycle. Talk about recycling! The end of the line comes when silicon fusion produces iron, which has the most stable nucleus of all the elements in the periodic table. Fusion of iron to still heavier nuclei doesn’t produce energy; it requires energy, so the energy-producing furnace stops there. The iron core quickly grows as the star produces more and more iron. When this iron core reaches a mass of about 1.4 solar masses, it has reached a magic limit of sorts, known as the Chandrasekhar limit (named after the great Chandra himself). At this point the pressure in the core can no longer hold out against the powerful pressure due to gravity, and the core collapses onto itself, causing an outward supernova explosion.”
― Walter Lewin, For the Love of Physics

“Consider, for example, that in one day a human body generates about 10 million joules of body heat. Unless you’re running a fever, your body runs roughly at a temperature of 98.6 degrees Fahrenheit (37 degrees Celsius), and radiates heat in the form of infrared radiation at the rate, on average, of about 100 joules per second; very roughly about 10 million joules per day. However, this does depend on air temperature and the size of the human being. The larger the person, the more energy s/he radiates per second. You can compare that to the energy radiated by a lightbulb; 1 watt is equivalent to the expenditure of 1 joule per second, so 100 joules per second equals 100 watts, which means that on average, people radiate at roughly the same level as a 100-watt lightbulb.”
― Walter Lewin, For the Love of Physics

“They all rely on a seemingly simple principle that’s pretty complicated in reality: if you put a conducting coil of wire (through which a current is running) in the presence of a magnetic field, then the coil will tend to rotate. How fast it rotates depends on a variety of factors: the strength of the current, the strength of the magnetic field, the shape of the coil, and the like.”
― Walter Lewin, For the Love of Physics

“play “Jingle Bells” on a wooden slide trombone in my class, and the students love it—I never tell them it’s the only tune I can play. In fact, I’m so challenged as a musician that no matter how many times I’ve given the lecture, I still have to practice beforehand. I’ve even made marks on the slide—notes, really—numbered 1, 2, 3, and so forth; I can’t even read musical notes. But as I said before, my complete lack of musical talent hasn’t stopped me from appreciating music’s beauty, or from having lots of fun experimenting with it.”
― Walter Lewin, For the Love of Physics

“Our poor ears can hear a pretty wide range of frequencies—more than three orders of magnitude, in fact—but we aren’t outfitted to hear the music of the heavenly spheres.”
― Walter Lewin, For the Love of Physics

“The characteristic sounds of a trumpet, oboe, banjo, piano, or violin are due to the distinct cocktail of harmonic frequencies that each instrument produces. I love the image of an invisible cosmic bartender, expert in creating hundreds of different harmonic cocktails, who can serve up a banjo to this customer, a kettledrum to the next, and an erhu or a trombone to the one after that”
― Walter Lewin, For the Love of Physics: From the End of the Rainbow to the Edge of Time - A Journey Through the Wonders of Physics