Do each app need to manually integrate with another app to be considered federated or is any app using ActivityPub automatically integrated to your app?
ActivityPub provides the framework, but a platform also has to be designed to support another platform. It’s not automatic.
Also why the seemingly arbitrary graduations, 24 hours, 60 minutes, 60 seconds. If it was say 10 hours in a day, 100 minutes in an hour, 100 seconds in a minute, seconds would be close to the same amount of time. Same with latitude and longitude, why 360 degrees in a circle with 60 minutes in a degree and 60 seconds in a minute.