Why did you modify the constant delta_t?

[kawa-work]

Dear Mr. Kreiss,
thank you very much for your great implementation.
I'm a master's student, studying pedestrian simulation.
I read Helbing's thesis "Social force model for pedestrian dynamics" and then this repository recently. I am very much interested in your works.
I have just a short question about.......(Helbing's uses 2s for delta_t, and your repository uses 0.4s??).
it would be very helpful if you could answer the above questions for me.
Thank you very much in advance.
Kind regards,
Kenta Kawakami