Professor Sampler’s Notes: Analog

Topics covered:

  • Definition of a continuous system
  • Definition of Analog Systems

An object is the same as itself – Aristotle’s law of Identity

All physical messages (or things, or signals) are analog in nature. The key feature of anything analog is that it is continuous. Our vision is an example of an analog signal. The imagery reproduced by our brain occurs to us as a continuous stream of visual information. We don’t sense breaks in our vision.

Zeno's Paradox
Zeno’s Paradox

This property of continuity is exploited by Zeno’s dichotomy paradox. To cover a certain distance, one has to first travel halfway there. To reach the halfway point, one has to first cover one fourth the distance and so on, ad infinitum. It would seem that there are an infinite number of steps to any point, and therefore the paradox concludes that one can’t even begin! The point is: the continuous nature of all things is tied up inextricably with our brain. A non-continuous space-time is inconceivable to man.

This continuity without boundaries is the reason we can ask the question ‘Why?’ ad infinitum in our quest to find the ‘first mover’ of any event.

Think about this: You are soaring above the desert like a bird. You literally have a bird’s eye view of the land. There should be a small mouse that roams somewhere on the sand, but you can’t see it from where you are. But you are hungry, and you descend to look closer. Soon you spot a speck – maybe it’s your meal, but you aren’t sure. You descend further, all the way down – you have to commit based on your instincts. If your instinct is wrong, you have lost valuable time. Make sufficient mistakes, and you will be left hungry. After all, the mouse isn’t going to stick around for you all day. Luckily for you, this particular speck turns out to be a mouse.

Now think about the mouse. It is running over the desert in search of its meal – a tiny insect perhaps? The insect is searching for its meal – smaller insects that in turn are hunting for micro organisms. A micro organism can see what the bird can never see. Reality exists as far as you want to go – either deep into smaller realms or beyond the edges of the universe. Our reality is without boundaries in either space or time. The signals we have found ready-made for our purposes are all around us. We just happen to call them analog signals. We are analog signals too. What do you think actors or dancers are doing when they use their bodies to communicate? They are signalling.

You see, defining continuity is probably a fool’s errand. It is good enough just to understand what it is, and then be at peace with it.

Any system or device that exclusively uses continuous analog signals is said to be an Analog system or device. However, one may often find ‘hybrid’ systems that use both analog and digital signals. An important question to ponder over is: Can a digital system exist without analog signals?


  • Analog signals are continuous
  • A non-continuous space-time is inconceivable to man
  • Any system that exclusively uses continuous analog signals is said to be an analog system

Links for further study:

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