length expansion

'Wag the dog' is an interesting phenomenon. Generally speaking, 'dog is shaking the tail' is normal, but conversely 'tail is shaking dog'. Figure 1. Normal phenomenon of a dog shaking its tail  Today, this word is used in many fields. When used in stocks, it refers to the phenomenon in which futures determine the flow of stocks. In the broadcasting market, it also indicates that the single personal broadcasting catches up with the regular broadcast. Figure 2. Phenomenon of wag the dog Wag the dog This word became widely known in original comedy movies. Shortly before an election, a spin-doctor and a Hollywood producer join efforts to fabricate a war in order to cover up a Presidential sex scandal.  So the president creates a war that could kill tens of thousands of people to hide his scandals. This is a summary of the movie content. So, the president drives the people's attention to war, and he overturns his political crisis.

  We looked at the Ehrenfest paradox last time. There are two issues in the Ehrenfest paradox. The first assumes a disc made up of an ideal rigid body, but when rotated at relativistic speed, it ruptures. The second is that the perimeter of a rotating body is different from its length when it is stationary. In the last post I looked at the first issue, and this time I want to look at the second issue. For those who have not read the first part, I will briefly introduce this paradox. It is best to read the previous post. Below is a link to the first part. The Ehrenfest paradox part I Rotating disc and length contraction   In relativity, objects that run very fast are said to shrink in length. So the official name of this is Lorentz - Fitzgerald Length contraction. It is not 'Einstein's length contraction'. This was born regardless of the theory of relativity. Before the theory of relativity was published, several people experimented to detect ether, but the e