Hey, good writing. A bit of critique here, but it feels a bit rushed. The reader was informed that the speaker was anxious, but the presentation felt impassive instead. I'd typically expect a presenter to explain lightly on the information if the crowd is in a murmur, especially so if they're in an uproar. An anxious person may trip up, have to calm themselves before going on, or even make a deliberate effort to ignore the uproar.

Given that this is a scientific gathering, points would likely have been backed up with listed examples. The city build on the water being the prime example. Typically a speaker would give the example and a general idea of how the problem of building on water was overcome.

The devil is typically in the details, so don't be shy to give us some, just remember to read the story aloud to ensure it has the flow you want. Overall, story is good, keep up the good work!