Welcome to week 4 of our course. I want to start off by just recapping our journey to this point a little bit as a reminder of where we've been and then point a little bit to where we're going this week and the following weeks. Even before the course started, of course, we had some video clips on the overall Goals of the course, a big one being a deeper understanding of Einstein, himself and more particularly, his special theory of relativity. We talked about, that sometimes involves a struggle for understanding, as Einstein put it. And that struggle though can be an ennobling experience, an enriching Experienced as we try to lift the veil a little bit of the mystery, again as Einstein put it, the mystery of the marvelous structure of reality. We also talked about how to succeed in the course, the idea that. It's a construction process really that we're building new mental models and we've gotta lay the foundations first and then build on top of that piece by piece. And so, we start off in week one looking at Einstein in context, and more generally the context of physics throughout the 1800s, leading up to Einstein and also some of the technology that came into play. So, we look at that and we'll bit more of the miracle your it self and nineteen zero five what that involved then we moved on in week 2 and look at definitions of what does it mean to have an event and how do clocks figure in to that. How dow we specify the location and time of a given event And so we looked at frames of reference, space, time diagrams as tools by which we can visualize events in space and time a little bit better. And also talked about the principles of relativity in that context. Then in week three we went on and considered that the second key principle in the Special Theory of Relativity, The principle of light constancy, which meant we talked about waves more, light waves, how waves work in general. That got us into a discussion, conversation perhaps, about the either, couple well-known experiments results, such as the Michelson Morley experiment, stellar aberration and just the puzzle involving all these things put together. How in the world do you understand what this either is all about with these somewhat conflicting results that they were getting in the later 1800's with this, right about the time when Einstein appeared on the scene? And I imagine that some of you at this point are saying When are we going to get to the good stuff? When are we going to get to the cool stuff, the weird stuff? Well, this week is when the weirdness begins. We're going to look at this whole idea as time is suspect. Before we get to that, let me just do our quotes of the week here. First quote, again, you can see these on your weekly handout. First quote is the eternal, from Einstein of course, the eternal mystery of the world is it's comprehensibility. The fact that it is comprehensible Is a miracle. This is somewhat similar to the quotes we had a couple weeks ago about simplicity, and we talked about beauty, how many physicists look for beauty in their equations with the underlying assumption that somehow if you have a beautiful equation that must connect with the actual physical reality. And Einstein is reminding us here that is just an incredible mystery. Why should our math works so well? Why should people talking about the unreasonable effectiveness of mathematics in terms of matching up with physical reality. Does it mean that all math matches reality, but a lot of it seems to. And Einstein is point out that, that eternal mystery here, just a good reminder as we think about these things. Second quote of the week we'll do is, gets at something else that really isn't part of this course, but it's a good reminder of another aspect of Einstein's life and work. He says my scientific work is motivated by an irresistible longing to understand the secrets of nature and by no other feeling. So, that really seeing in our course. Irresistible longing to understand the secrets of nature. But then he goes on and says, my love for justice and the striving to contribute toward the improvement of human conditions are quite independent from my scientific interest. And what this does is it reminds us that as you may know, when Einstein became a world figure starting in the 1920s a lot was going on then. And he spoke out on things against war and militarism and some of the other things going on, the anti-Semitism in Germany. And he was greatly affected by it as well. He had at least one lecture, he was giving a public lecture that was disrupted by. Anti-sematic protesters. This was during the rise of Nazi-ism in Germany in the 1920s and into the 1930s. His life was probably in danger at certain points and eventually he ended up having to Leave Germany for good. So love for justice, striving to contribute toward the improvement of human conditions, he's saying it was independent from his scientific work. And that's a good reminder. Sometimes we want Want to tie everything up in a nice little ball in terms of a person's life and work. That if he's doing this great scientific work, it must have some connection to his other work as well, maybe principle of relativity, everything is relative or something like that. In actual fact, that may be true, but it may not be true. And in Einstein's case, there was more of a disjunction between his scientific work And his work for justice and speaking out on those types of issues. So, quotes of the week there. We could add another quote of the week perhaps. And though we talked about this before, that in 1905 he had been struggling with these notions of these two principles, the principle of relativity. And the principle of light constancy are sort of in conflict with each other. There were some asymmetries involved in the theory of electromagnetism in particular, and also in trying to apply the principle of relativity to that. Electromagnetism seemed to apply. There was an absolute reference frame. In other words, the either. That, on the other hand, and that came from the principle light constancy. Light as a wave, there must be some medium through which the light moves. And you have the principle of relativity, which is well established as well throughout physics. Said, no, there is no absolute frame of reference. And so, he was struggling to To bring these two principles together and in the conversation Michele Besso his friend from the patent office, who's working at the patent office at that time. They've been friends before that in latter discussions he went home after it and came back the next day and told Besso that I figured it out. You helped me and I had that flash of insight. And then later on in his life when he's reminiscing about this, he said he realized that time was suspect. So that's what we're going to explore this week to start off with and then see what he means by that and see where that takes us.
