What symmetry means in science

6:03flip around. So you can imagine if I were to take that photo of the Taj Mahal and then flip it >> right along the middle, I would get the same exact Taj Mahal. >> That means that it's symmetric. >> Does that mean does that make sense? It's symmetric upon reflection of that central axis. Yes. Now there's other kinds of symmetry and and we're used to it. Like for example, there's shapes that we can do. And what we can do is not just reflect along the central line. We can reflect along many lines. For example, the heart, the heart shape, you can reflect along the central line. The butterfly you can reflect along the central line and the and the the wings will go from one to the other. A square you can reflect along the central line on both axes and also along

6:45the diagonals and the square is going to come back to be the same square. Okay. There's another way to do symmetry not just with reflections. You can also do rotations of objects. If you look at like the red cross, the cross of the red cross or the thing that's in the middle of the Swiss flag, >> right? You can rotate that cross 90 degrees >> and it'll be the same cross, right? But if you take an arrow and you rotate it, it's going to point the other direction, right? It's going to point from up to left or whatever, however, however you do the the 90° rotation. So [snorts] in that sense we kind of know what symmetry means for um objects >> like thingies right um 2D things 3D

7:27things you can even think about a sphere right you can rotate a sphere in any direction and it's a continuous symmetry because no matter how you rotate the sphere it's still going to be a sphere >> and you can do similarly with a cube but only not in any direction but in certain explicit yes >> degrees of rotation. >> Yeah. And actually the five platonic solids that are our logo, you can you can rotate them in three dimensions and you'll come back with the same exact platonic solid. Right? So >> we're used to objects being symmetric, but in the early 1900s there was talk about maybe there's symmetry in the physical laws themselves. >> Okay. >> Okay. There's stuff you can do to

8:09physics laws that leave the physics laws exactly the same. >> Okay. >> Okay. >> Okay. I hear what you're saying. >> Yeah. So, let let's let's [laughter] dig into that. This was actually first um first sort of codified by um someone by