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Hey guys! So much in the same way that we started the last series by asking some questions about what is light. We're gonna start this series by asking some questions about what is anything. So let's say for example you say what is the difference between the skin on my arm and a rockthat may seeminitially （乍看）obvious. You say why a rock is a rock and the skin on my arm is skin. But what does that statement actually mean? What if we have metals? What's the difference between metals and a rock? We know that you have a metal likecopper（铜）oraluminum （铝）.You canbend （使弯曲）it. You can if you are strong enoughstretch it （延展它）twist it （扭曲它）and it wouldn't break. But if you did that with arock it's gonnashatter （碎裂）. Maybe I don't know if everyone's done this. But I remember as a kid throwing rocks off of a bridge into a lake sometimes they would hit other rocks and they would just shatter but the break would always beclean. So what then differentiates for example our skin from an elephant's skin? Because clearly we know that that would be very different. They would feel very very different. But they're both still kind of skin. So this is kind of where we're gonna start things. Let's say let's try athought experiment （假想实验）. Let's say for example you have a piece of chalk and you break this piece of chalk into two. You still have two pieces of chalk now just smaller. So then youtake that chalk and you break it again you break it again and again until it'sso small that you can't quite break it.Your fingers are too big. So then you get a powerfulmicroscope （显微镜）and you get littletweezers （镊子）you continue to do it break it apart again and again and again. Is it still gonna be chalk? I mean you might think well I know that an eraser for a chalk board when Iclap （拍打）it clap two of them together I getchalk dust （粉笔灰尘）. It seems to have the same white color the chalk does. Or you know if you were using colored chalk it would be red or green or whatever color. So then that means that our chalk is still chalk as we break it into smaller and smaller pieces. But is there a limit to this? What if everything was made up of one one thingjust the same thing? Well interestingly enough this was this is a concept that's existed since all the way back to theancient Greeks（古希腊）. And what we're just going to do right now is we're going to skip ahead a little bit to about the 1700s when chemists or scientists at the time were finally starting to see that there were certainchemicals （化学品）that they couldn't break down further. And they were calling these chemicals elements. And the idea being that these elements were actually what made up everything else. And at the same time that this was happening there were somescientists who were investigatingstatic electricity （静电）. They knew that if theyrubbed （摩擦）two materials together they woulddevelop charge（起电）. They would attract each otherorrepel each other （互相排斥）. But it wasn't clear how this was happening. Was it an exchange of something? Was there some sort ofdeficit （减损）on one material and asurplus （增加）of something on the other one? What was happening? Interestingly enough all these questions are gonna kind of come together to create a basis for on which we're gonna learn and understand how nuclear physics came to be. And then we'll tieit together with some of the stuff we talked about inquantum （量子力学）last time. And that'll be hopefully very informative. So see you guys next time.
There were some scientists who were investigating static electricity. They knew that if they rubbed two materials together they would develop charge.They would attract each other or repel each other.
There were some scientists ∧who were investigatingstatic electricity.〡Theyknewthat if they rubbedtwomaterials together∧they would developcharge.〡They wouldattracteach other∧orrepeleach other.
失去爆破：rubbed two would develop
连读：static electricity that if would attract attract each each other repel each