Conceptual Science

In  Chapter 5 of the Feynman Lectures Richard Feynman takes us on a journey into the realm of  small distances , showing how scientists probe the world beyond the limits of direct observation. His explanations are rich with analogies and imagery, making complex concepts more accessible. In this post, we’ll explore his key ideas, unpack his vivid examples, and add further details to bring these fundamental principles to life. Breaking Down the Metre: From Millimetres to Microns Feynman begins with a simple idea:  subdividing a metre . Anyone can take a ruler and divide a metre into a thousand parts to get  millimetres . With some effort and the aid of a microscope, we can go even smaller, dividing a millimetre into  microns (micrometres, or  10^-6  metres) . But here, a natural barrier arises—our eyes can’t resolve details smaller than about 5 x 10^-7  metres , the wavelength of visible light. This is where Feynman’s imagery becomes striking: ...

In  The Feynman Lectures on Physics , Chapter 5-6, “Large Distances,” Richard Feynman takes readers on an intellectual adventure through the vast scales of the universe. He starts with something as simple as measuring with a stick and gradually expands the discussion to astronomical distances, introducing clever techniques for gauging the size of planets, stars, galaxies, and even the observable universe. His approach is a masterclass in teaching—blending vivid imagery, logical progression, and relatable examples to make abstract concepts feel tangible. Let’s explore how Feynman explains the measurement of vast distances, his pedagogical techniques, and how he makes complex ideas accessible. From the Thumb to the Stars: Building a Sense of Scale Feynman begins with an almost childlike question:  How far, or how big, are things?  His initial answer is reassuringly simple—we measure distance by taking a stick (or a thumb) and counting units. This grounding in everyday exper...

In Chapter 5-5 of  The Feynman Lectures on Physics , the evolution of time measurement is explored, highlighting the transition from astronomical observations to atomic standards. Historically, time was gauged using natural phenomena like Earth’s rotation, leading to the definition of a second as 1/86,400 of a mean solar day. However, as measurements became more precise, it became clear that Earth’s rotation is not entirely uniform due to tidal friction and geological activity, prompting the search for more stable timekeeping methods. The advent of atomic clocks marked a significant advancement in precision. These devices utilise the consistent vibrations of atoms, such as caesium-133, to measure time with remarkable accuracy. Unlike Earth’s rotation, atomic oscillations remain largely unaffected by environmental changes, making them far more reliable. In 1967, the International System of Units redefined the second as the duration of 9,192,631,770 cycles of radiation associated wit...

Richard Feynman was a master at taking deep scientific ideas and making them intuitive through rich, everyday imagery. In  The Feynman Lectures on Physics , Chapter 5-4, he explores the concept of measuring long spans of time, weaving together natural cycles, geological markers, and radioactive decay. His use of metaphor and example makes the abstract nature of time tangible, offering a narrative that spans from counting days to contemplating the origins of the universe itself. Time as a Cycle: The Familiarity of Days and Years Feynman begins his discussion with a simple, intuitive observation: we measure time in familiar cycles. The most immediate of these is the day, defined by the Earth’s rotation. But for longer spans, we naturally turn to another cycle—the year. Here, his imagery is straightforward yet profound:  “First we find that there is another natural periodicity: the year, about 365 days.” This transition from daily to yearly cycles is a subtle way of introducing t...

In Chapter 5-3 of  The Feynman Lectures on Physics , titled “Short Times,” Richard Feynman delves into the evolution of measuring increasingly smaller intervals of time, illustrating the ingenuity and progression of scientific techniques. From Days to Seconds: The Pendulum’s Precision Feynman begins by highlighting the transition from using the Earth’s rotation to measure a day to subdividing time into smaller units. He references Galileo’s observation that a pendulum’s swings are isochronous—each swing takes the same amount of time when the amplitude is small. This discovery led to the development of pendulum clocks, allowing for the division of time into hours, minutes, and seconds. By calibrating a pendulum to complete 3,600 swings per hour, the concept of the “second” was established, effectively dividing the day into approximately 86,400 parts. Advancements in Time Measurement: Electronic Oscillators Recognizing the limitations of mechanical pendulums in measuring extremely sh...