Time Before Time

Dr. Daniels explained the time before time theory to his friend. 

“Jeff, time proceeds forward at one second per second.” 

“Stop! So we travel through time just like there was no theory. We just go forward.” 

“Yes. Now, however, with this time machine and that time machine,” pointing at the two similar treadmill-looking devices, “we can alter the passage by one minute either way.” 

“Stop! So if I get on this machine, I will end up one minute ahead in time.” 

“Correct.” 

“But, if I get on that machine, I will be one minute in the past.”  

“Right again.”  

Jeff slapped the doctor on the back, jumped onto the nearest machine and walked for one minute. 

“Well, that proves nothing, Doc. I would have been here anyway. Let me try the other one.” 

Jeff got on and then off the other machine. 

“Okay, Doc. What’s this time before time theory?”