system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] In Iron Man 2, what exactly does Tony do to create the new core for the arc reactor and how did he get that information from his dad’s old stuff from the World’s Fair?

I know it has something to do with rearranging the pavilions into a model of something but what exactly did he do?
gpt
Howard Stark's study of the Tesseract led him to theorize the existence of a new element that could serve as an exotic power source. At the time, however, there was no technology with which he could synthesize this theoretical element. What he hid in the pavilion was a model of the atom so that Tony could synthesize it in the future when the tech was available. 

edit: He creates the new element by throwing together a makeshift particle accelerator in his basement.