metrology

Adam Savage shows a set of Mitutoyo ceramic gauge blocks and uses them to explain metrology, the science of measurement. He argues that accuracy and precision work differently than most people assume, which changes how you think about every measuring tool.

Veritasium explains the effort to redefine the kilogram, which was still defined by a physical artifact, and how a near-perfect silicon sphere from the Avogadro project helps. It also covers the history of the unit's odd naming.

Veritasium visits NIST to explain Standard Reference Materials, the carefully characterized items such as peanut butter used to calibrate instruments and keep measurements consistent. It covers why they exist and why they are expensive.

Veritasium explains why the kilogram is being redefined in terms of Planck's constant rather than a physical metal artifact. It visits NIST to show the Kibble balance and why measuring mass precisely is hard.

Marco Reps builds and tests an open-source 8.5 digit voltmeter based on CERN's high-precision ADC design. The video walks through assembly, soldering and measurement of the resulting instrument.

A look at how granite surface plates are inspected, calibrated and reconditioned using an autocollimator, a repeat meter and diamond-charged cast iron laps. Measurements are at the level of millionths of an inch.

Tom Scott investigates the claim that the microwave was invented to heat hamsters, and interviews James Lovelock about freezing and microwave-thawing hamsters in the 1950s. It traces early magnetron uses beyond radar.

Physicist Carlo Rovelli gives a public lecture at the Royal Institution on how our understanding of time has changed, from Boltzmann and Einstein to quantum theory and loop quantum gravity. He blends physics, philosophy and art to argue that time is stranger than everyday intuition suggests.

CGP Grey explains the elegant ratio of A4 and the metric paper sizes, then zooms out across scales from the Planck length to the observable universe.

CGP Grey explains the mess of Daylight Saving Time, including its dubious energy savings and the odd cases like Arizona that opt out. It is a short, simple explainer.

Tom Scott follows the ISO 3103 / BS 6008 standard to make an international standard cup of tea, using specialist tasting equipment. The video shows how precisely the standard is specified.

An animation presenting a non-standard helical or vortex model of the solar system, in which the planets trail the Sun through space instead of orbiting in flat circles. The model is a non-conventional view that the author says differs from standard diagrams.

Veritasium explains that the US signed the Metre Convention in 1875 and that all US customary units are officially defined in terms of metric standards. It also touches on the standard kilogram.

Machine Thinking traces where mechanical precision comes from, from flat surface plates and the three-plate method up through lathes and early measuring tools. It is the first in a series on recreating the first micrometer.

Dan Gelbart shows his home-built air bearing CNC lathe and grinder, which reaches about 1 micron accuracy. He demonstrates the machine and its parts.

Dave Jones of EEVblog demonstrates that a frequency counter can detect gravity through the 2g tipover effect on quartz crystal oscillators. He shows the reading shift as the instrument's orientation changes.