objects on the floor because the other robot is not ready to catch them. Once these two robots agree on that zero time, they are phase synchronized. Now when you see video of robots working together to assemble a car in an automobile factory, you'll understand that they need phase synchronization to ensure not only that they get the job done but that they don't crash into each other. You might detect a slight flaw in this scenario, because the sender robot is dropping the object at 0.400 and the receiver robot is opening its hand at the same time. If our robots are only phase synchronized to a low degree of precision (for example, only 50 ms), the sender robot could be 50 ms ahead of the receiver in time. There- fore, the sender robot could drop the object up to 50 ms before the receiver has its hand in place, and the object could drop on the floor. The solution would be either to reduce the allowable time difference between the ro- bots or to put an extended wait time in the program in case one robot gets too far ahead of the other. The resulting slowdown in production would be money wasted. So, the closer the alignment, the faster the pro- cess can be made to go, as you can remove extra wait times. You will see that the same issue arises in commu- nications systems in "Chapter 2. Usage of Synchronization and Timing". You can see that there are many processes in our modern world where groups of devices, although separated by distance, need to agree on phase and to be phase synchronized or phase aligned to a high degree of accuracy. This alignment accuracy is commonly expressed in terms of the phase off- set between the two devices and represented by the Greek letter theta (0). For the robot scenario to work, the robots might need to be phase aligned to within about 5 ms to eliminate the risk of objects falling on the floor. This degree of alignment might not seem too diffi- cult, because the robots are very close to each other and connected to a high-speed local-area net- work (LAN) infrastructure. In a modern 5