Twin Paradox Twin paradox started as a contradiction in ‘time delay’ in Special relativity. The Twin Paradox goes something like this: (Contents vary depending on the media.) One of the twins stays on Earth, and the other leaves Earth in … more

## 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 to express a four-dimensional coordinate system (x, y, … more

## 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 above simulation.) The meanings of the symbols used … more

## 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｡ = The transit time of light observed inside … more

## Bubble Pop

Icon Title Try popping the falling drops with your body. If your PC doesn’t have a camera, it won’t work. When the web browser asks for access to the camera, please allow it. (Personal data never stored on the server.) … more

Categories A.I

## 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 refraction of all light entering a crystal ball. … more

## ‘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 a shape with a small moment of inertia? … more

## 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 these photoreceptors have evolved into light-sensing cells of … more

## 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 of the object is scattered all over the … more

## 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 an equilibrium state at a constant temperature, the … more

## 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 other. The vibration mechanism is simple, so it … more

## 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 a light or dark pattern depending on interference. … more