system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do eggs become solid when we cook them?

Why do eggs become solid when being cooked?
gpt
Eggs contain a lot of proteins. Proteins in normal states have a very precise structure and there are 4 levels of that structure. While proteins have their structure intact, they look like a ball of tangled string. If you heat up these proteins, they start to unwind, destroying this tangled webs of bonds and unwinding. Now, proteins are really long, while tangled they occupy a little space but when untangled they are super long and act like interlaced book pages and its harder for them to move. They change from a gel-like substance to a solid. Internal structure of these proteins lets light go trough it but once they are untangled they stop light, thats why they change from a transparent gel to a white solid.

EDIT:
The process in known as denaturation and occurs not only due to heat, read about it on wiki, theres a lot of info about how the process works.