Tanya Bub

While I am the first to recognize the importance of teaching physics conceptually (I literally teach a conceptual physics class), I don't know if this book does such a good job tackling relativity in a purely conceptual way. I keep asking myself: what is the point of this book? To raise some "strange" head-scratching issues that relativity brings up? To lead to a good conceptual understanding of relativity? Something else?

The authors take five different relativistic scenarios and walk through them conceptually, using fast-moving trains as a platform. Scenario 1 just has to do with the fact that light always moves at one speed, regardless of the initial motion of that light. The example is shooting a light gun from different spots on two different speed trains and watching where the light waves / photons propagate. Scenario 2 discusses simultaneity by shooting Alice and Bob simultaneously with a light gun, but also shooting Alice first, and also shooting Bob first. Scenario 3 gets into length contraction using a bunch of balloons arrayed at angles to see how far light will travel on two cars moving at different relative speeds. Scenario 4 describes the collision between two moving pieces of putty to explain E=mc^2. The last "bonus" scenario is about a chicken and egg situation when moving at relativistic speeds.

I thought the first two examples were good, and I understood them and felt relatively satisfied. I have no rigorous background in relativity, but I'd like to think I understand the basics in a so-so way. Even though I wasn't surprised at the outcomes of the thought experiments in this book, I still found myself completely confused after reading scenarios 3-5. While I guess the purpose was to discuss length contraction and E=mc^2, but those ideas were totally lost on me.

The issue is -- without ANY math at all (and especially without understanding non-linear math), it's hard to make sense of any of the conceptual examples. I sort of understood the balloon thought experiment (scenario 3) but wasn't sure what it told me that scenario 2 didn't. Scenario 2 was enough to discuss length contraction and time contraction... what were the balloons for? And why couldn't the balloons be a discussion about trigonometry? While reading the example, I thought "oh, that sounds like the cosine of 30 degrees, why didn't they just say that?" but of course, there is no math in this book. I read through scenario 3 twice and then a third time, and even drew pictures, but nothing clicked as far as what I was supposed to understand about relativity.

Scenario 4, about momentum and how E=mc^2 was derived, I found even more hard to follow. I hate to say this about a book, but I found myself wishing that this were a YouTube video instead of a book.

Scenario 5 just totally lost me. It's a cool thought experiment, I guess, but it was so quick and even after re-reading, I had no idea how everything was supposed to work out.

I don't know... try it out maybe if you're interested in relativity?… (lisätietoja)