I am glad that further readings are confirming the arguments of two previous Blog entries. And all this is showing me the beauty and utility of randomness.

First I found in Fermilab site a wonderful answer to a question about radiation direction, which supports the core idea of the light clock entry. Since the text is long and dense, I have fished out and highlighted the relevant passages:

“radiation is emitted randomly (...) you cannot predict the angular direction...

I got interested in the so called “observer effect” because it has an application in economics, in the context of the current crisis. In physics, the said principle warns that the act of observation (more technically, measurement) may affect the observed phenomenon, for example because the measurement instrument interacts with the measured object. This can happen at macroscopic level but must happen at microscopic, quantum level. For instance, in order to “see” the position of an electron, one has...

The other day, when trying to explain the space-time interval to a friend, I hit upon a metaphor I would like to share. (I am simplifying and considering only events that are timelike.)

Think of that most common situation, where a cat has climbed on top of a tree but cannot go down. A man (“Man 1”) by the bottom of the tree (point “P1”) places a ladder and measures the distance he has to climb in order to reach the top (point “P2”) and rescue the cat. This distance is ∆y,...

Dalespam recently brought up an interesting semantic issue. What is the meaning of “relative” versus “absolute”? I did not have time to intervene in that thread but the subject links well with the musings of this Blog.

Obviously “relative” is what is defined “in relation with” or by comparison with another object, but in the context of Special Relativity this may mean three different things:

(a) That a measurement (of time or space) is made from and hence with regard...

Last post ended with a question: when a physicist plays with clocks and rods and kinematic concepts like time, displacement, velocity, acceleration… what is his or her Cinderella, that is to say, the practical purpose that he or she has in mind?

Seeking an illustration for the answer, I reviewed the problems posed in a standard physics book. Unfortunately, the questions stopped at the abstract level. They asked, for example, about the velocity of a projectile after the lapse of a...