# Author Archive: DongJoon

## Minkowski Spacetime

Minkowski Spacetime Minkowski spacetime (or Minkowski space) is a coordinate system devised by German mathematician Minkowski. The peculiar thing is that the coordinate system contains space and time. Minkowski spacetime uses matrices…

## Special Relativity: Length Contraction

CAUTION: Read the following instructions to the end to get the result that the moving object appears to be constricted in length. (It is difficult to explain ‘Special Relativity’ only with the…

## Special Relativity: Time dilation

The meanings of the symbols used in this simulation are as follows. L = Distance that light travels in a stationary state, (=ct｡) c = Speed of light (≒ 299,792,458 m/s) t｡…

## Why do we always have crystal ball covered?

Why do we always have crystal ball covered? While surfing the web, I came across a fascinating article on Twitter. It sounds like a fun topic, so we decided to simulate the…

## ‘Moment of inertia’ of various shapes

You can click various shapes on the left and right sides of the screen. What are the characteristics of a shape with a large moment of inertia? What are the characteristics of…

## Evolution of the eye

Flagellate Hundreds of millions of years ago, light-sensing organelles arose inside the monad. Creatures with ‘photoreceptors’ are able to distinguish day and night and can also avoid harmful ultraviolet light. Flatworm And…

## Correction of Near-sightedness & Far-sightedness

Focusing The light started from the object must have arrived exactly at one point on the retina to see things in detail. On the other hand, if the light from one point…

## Equilibrium Constants

2●$$\rightleftharpoons$$● Chemical equilibrium In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations that have no further tendency to change with time. In…

## Tuning Fork and Sound Wave

Tuning fork The tuning fork has a structure that combines the ends of two sticks. When the tuning fork is vibrated, the tuning fork repeatedly approaches and then moves away from each…

## Double-Slit Experiment

Double Slit Experiment The double-slit experiment is the observation of the pattern that a single wavelength of light creates after passing through two slits. Light passes through each slit and then creates…

## Polygonal Wheel

Polygon Wheel Should the wheels always be round? All polygon wheels can roll smoothly. To do this, you need a suitable floor. How is the floor for the polygonal wheel to roll…