“Wednesday” is entirely a social construct. Which is to say that Wednesday doesn’t exist except in the sense that we say it exists (along with weeks, weekends, and months). So in that sense, it’s Wednesday (or…now Thursday as of this writing) because we all agree it is. There are plenty of calendars that don’t have the concept of Wednesday and therefore it is never Wednesday: bit.ly/AltCalendars. Other time concepts (such as seconds, years, etc.) are derived from the natural world around us and proof for them is a bit more complex.