The Passage of Time in the LSB

I'm currently sitting at work in the IT office of the LSB. There are a million (not literally) ways that I could see the passage of time.

• Clocks. Each computer has a built-in clock that displays even when you are not logged in
• Erosion. While the wind/water erosion in this office is practically nonexistent, there is an air conditioner running. Technically, the desks, walls, and floors will slowly erode as time passes.
• Dust. The accumulation of dust in this room will increase as time moves on
• Every single night, under the cover of darkness, the custodial staff comes into this room to clean it. I could probably sit here and keep track of each day by the number of times I see the custodial staff enter
• Sunlight. While I can't see the exact position of the sun from our window (it is directly opposite another window in this building), I can see when the day changes from day to night
• Since most of the employees here are also students, I can probably tell what time of year it is by how many employees are regularly coming in for work. When it is spring/summer, there will be markedly less employees working
• Also, I could probably tell the nonspecific passage of time by the employees that are employed and then leave. Since most employees will work here for about 2 to 3 years, I could probably guess how many years go by by how long someone is employed
• There are also full-time employees who work here. I can keep track of time by how old they are. Of course, I could also just ask them what the date is

...Or I could just use my cell phone.