 Hey everybody! We're here today to talk about energy, and I'm pretty sure that if we did a little study on how I start every lecture, we would discover that I announce at the beginning of every lecture, this is the favorite topic that I have. This is my favorite topic to lecture on. I can't help it even though I know that that is what I say about every topic. I love talking about energy. So we're going to spend an entire lecture today talking about this concept. Now, it might, we might be like, dude, energy, like how complicated can it be? And I'll tell you right now that you're probably going to want to take a physics class or maybe a physics class and a chemistry class in order to really get your head around energy and all the different kinds of energies and all the rules around energy. But we're spending an entire lecture today so that you don't have to do that to appreciate how energy works in biological systems. We're going to lay a foundation today that's critical to our next two lectures where we're going to talk about cellular mechanisms, things that happen inside cells to produce energy in living systems. So today, so we basically have a three lecture series on on energy in cells. I looked for a different picture to introduce our lecture today and I don't, I don't have any other picture that is such a lovely quintessential expression of energy. This is my brother on his wedding day leaping from standing over the top of his bride to be while singing a song to her in the actual wedding, like this thing that you are witnessing here occurred in their wedding. If anybody thinks I have a lot of energy, my brother has about eight times as much energy as I have. He's a very entertaining human and this leap over the top of her head was unscripted. His wedding was very scripted. It was in a theater. It was like it had parts and acts and skits and songs and it was like a super creative, entertaining, high-energy event. And this leap was done because he felt like his song was becoming a little boring. The one thing that he was thinking about at the time that he leapt over her head is, oh gosh I hope my pants don't rip. His pants didn't rip. I'm very curious. This wedding was in, I think 2009. It's 2023. I'm super curious. Could he still pull this off? I guarantee my 2009 body can't do my 2023 body. Can't do the things that my 2009 body used to be able to do, but my brother's a whole nother story of athletic prowess and energy. So I think that they, their anniversary is coming up here. I think we should have a redo and see like does he still have this kind of energy? Does he still have those haps? I don't know. Before we begin, let's get a definition of what energy is so that we have a starting point. And I am just going to apologize in advance for the fact that our definition is not super helpful, which is one of the reasons why we're going to spend an entire lecture like chewing on this and figuring it out. Energy is the ability to do work. And I guess like seriously? Like what? Come on now. It's the ability to do work. That seems so random and so weird to me. And it's, I think it's important to accept that that's how we know if there was energy involved in some scenario. It was there a capacity to do work. I think we also need a definition of work because, dude, what even is that? Like, yes, we have a sense. I washed a floor today, which is a small miracle that I did something like that. I consider that work. Does, how does that relate to energy? Well, work is basically it's a equation where it's force times distance. So work happens. I'm just going to write work on here as well. Work happens when you apply a force to something and you move something a distance. The amount of work is related to the size of the force and the distance that something is moved. And it takes energy to do that. So if you do work on something, you move something, you apply a force and you move it, then there was energy involved. Like I said, we're going to spend the entire lecture hashing that out because if you hear that explanation and you're like, okay, yeah, cool. You have an amazing brain that is like super mathematical and physics-ish and you're super lucky because for me, it takes way more for that to become intuitive. The first thing that we're going to talk about is the different kinds of energy. And I think that that will start to help you visualize this actual definition a little better.