Synchronization: The Coupling of Two Or More Systems

If you pick up your dictionary and check the meaning of this word, you would probable find synonyms such as synergy, simultaneously, harmonious etc. this is the concept I want to discuss with respect to physical systems.

Synchronization has find application in various fields and continues to gain interest from scientists and engineers alike.

Theoretical physicist have used the concept of synchronization to achieve coupling of two or more system in schemes such as complete synchronization, phase synchronization, lag synchronization, generalized synchronization and time-scale synchronization.

Synchronization schemes has also been used in electronic circuit used to generate radio-frequency power, lasers and many other oscillating chemical reactions, pacemaker (Sino-atrial nodes) of human hearts as well as artificial pacemakers used in cardiac pathologies.

Synchronization can also be seen in nature. Nature has implemented synchronization schemes in various ways such as the adjustment of biological clock (since all living systems are made of such clock) which regulates the daily or circadian and seasonal rhythm of living system. This schemes controls phenomenon such as aging, development, and other natural activities living systems undergoes.

This synchronization scheme can be viewed as a unidirectional scheme in that living system has no influence on the movement (rotation/revolution)of planets and celestial bodies (if you believe on the influence of the latter on living system) and yet they influence living systems.

My earliest contact with synchronization was about a decade ago. A friend back then in school was working on master-slave synchronization of two systems. In this scheme, a system is considered as the master which is then used to “drive” the slave. I later realized that this can also be done for more than two systems in which the master set the pace for the slave and they move together while each still retains its individual properties. He asked that I helped him with some of the mathematical operations which I gladly obliged. Although I never did any research on the scheme myself. I find it enthralling.

What then is Synchronization?

The word synchronous is gotten from Greek word [synkhronizein] which means time and common. Therefore, synchronization means sharing common time or occurring at the same time. Are you thinking about such events that occur at the same time?

One of the earliest scientist to talk about synchronization was [Christian Huygen], in 1665. Huygen discovered that two clocks placed side by side and hanging on weak beam after some time starts to exhibit synchronous movement. These clocks are said to exhibit mutual synchronization and in modern terminology, the two clocks were in anti-phase synchronization which is as a result of the coupling through the common beam holding them in place.

Synchronization phenomenon has gained adverse application in so many areas. Notably, the triode generator which has become fundamental to radio communication systems is synchronized by allowing frequency of a powerful generator to be driven with the help of a weak one but very precise one.

Let’s talk about synchronization in biological systems. Yes I mean living systems. Like I mentioned in my introduction in this article, biological systems are made up of internal clocks that ensures the systems goes through day and night, and the organism can be aware of the changes going on. Changes like aging, blood flow, heart activities, and lungs activities and so on. Biological systems go through these changes day and night. You might also want to link this internal clock to the life span of living system. Even though there are no natural disasters, there are not accident, selection by nature and any other thing that might cause a living thing to die, be sure that eventually the internal clock will wear out or “run out of battery” and eventually shut down. You might think that not all living things die a natural death, but eventually they die one way or the other.

Synchronization can therefore be viewed as the regulation of rhythms of an oscillating object as a result of their interaction with another.

It is important to know that for synchronization to be achieved between two systems, they must have certain properties in common.

What Synchronization is not

It may be tempting to think of synchronization as a form of resonance. Well, I want you to know that synchronization is not merely resonance in any way. Let me explain this. Resonance can occur in any oscillating system where another system is used to sustain its oscillation. That means the system is not self-sustained.

Synchronous variation should not also be confused with synchronization. Synchronization is mainly applicable to systems that are decomposable and not applicable the ones that are not. An example of non-decomposable system is [hare and lynx population data] for predator-prey system.

Also, synchronous motion should not be confused with synchronization. These two can sometimes be different form each other. For example, consider a situation where two pendulum clocks are connected mechanically via a rigid link, one which establishes a strong coupling between the clocks. If eventually one of the clocks stops or the pendula moves synchronously, it will not be regarded as synchronization due to the existence of the strong coupling which place a restriction on the motion of the system thereby can be regarded as non-decomposable.

Vaguely, what I am saying in essence is that the coupling of the two systems should not be such that it has the ability to change the behavior of the systems involved or deprive them of their properties which makes them individual and not a single system.

In summary, synchronization of two systems is said to be achieved if the two systems are self-sustaining oscillators such that they are capable of existing on their own and generating their own rhythm. The system adjusts their individual rhythm due to weak coupling and not strong coupling which may enforce a restriction on their individuality.

It is also important to note that synchronization is to be seen a process (a complex dynamical process) and not a state of systems.