Hello, and welcome back to MPC! Last week, we had an exciting discussion about causality. At the end of that discussion, I said that we would soon be combining the major concepts that we have been discussing since last month: the spacetime interval, light cones, and causality. However, before diving into that, I would like to take a brief break from special relativity. With this being the 25th blog post on MPC (wow!), I would like to take this week to reflect on what we have discussed and what we will be discussing in the future.

It may not seem like it was too long ago, but the first post on MPC was published in the beginning of January! We started off by discussing the differences between classical physics (physics dating back to the work of Sir Isaac Newton, Michael Faraday, etc.) and modern physics (the physics of the 20th century).

From there, after a brief review of basic physics, we jumped right into relativity! We spoke about the importance of relativity and what it truly means to be relative to something. We then talked about the luminiferous aether and how the results of the Michelson-Morley experiment disproved its existence. We also spoke about the constant nature of the speed of light and how it seemed to defy the well-established Galilean transform. We also mentioned the supposed “constant nature of time” (although we would later go on to refute it)

Following this, we were ready to begin our study of special relativity. We started off by discussing the two major postulates of special relativity:

- The laws of physics are the same in all inertial frames of reference.
- The speed of light is constant in all inertial frames of reference.

From there, we decided to throw away our preconceptions about how our world works so we could learn about such “radical” ideas as time dilation and length contraction. These ideas have completely reshaped the human race’s understanding of our world, and I hope you found them as amazing as I find them! We discussed the implications of these phenomena, such as how they suggest that time and space are not absolute. This led us into our discussion on spacetime. We spoke about the spacetime interval, spacetime diagrams, light cones, and, just last week, causality.

It’s been quite a ride! I have had a great time writing these posts and I hope that you have been able to learn at least something from them. That being said, we are just getting started! This summer, we have a lot of exciting things to discuss. Next week, we will wrap up our conversation on spacetime diagrams. Then, we will start discussing general relativity (if you thought special relativity was awesome, just wait!). We will be discussing general relativity for a few weeks; due to the mathematical complexity involved with general relativity, though, we will not spend as much time on it as we have spent on special relativity. After general relativity, we will begin our study of the other half of modern physics: quantum mechanics. We will be discussing such amazing phenomena/events as the ultraviolet catastrophe, the photoelectric effect, wave functions, quantum entanglement, and more! There’s a lot to be excited for!

That’s all for this week. Thank you to everyone who has been reading these post! I hope that you will continue tuning into MPC to learn more about modern physics! As stated previously, next week, we will jump back into our discussion of spacetime intervals, light cones, and causality. See you then!

(featured image: https://vignette3.wikia.nocookie.net/balloons/images/4/4a/Maxresdefault1.jpg)