I mean a bit of information (data). Some say (do not know exactly who) everything on its smallest level consists of information. What does the information consist of?
closed as unclear what you're asking by Swami Vishwananda, Dan Hicks, Jordan S, Tim B II, Conifold Dec 28 '17 at 1:25
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If by bit we mean a mathematical 1 or 0, then there is no smaller unit of information.
But if we are talking about implementations of bits, then a bit has smaller constituent parts. An electrical engineer can calculate the number of atoms that make up a bit in a particular semiconductor material. Read world bits are made of atoms. Same as if you used a sequence of coins showing heads or tails to represent a bitstring. Each coin is made of atoms, quarks, strings, whatever level of discourse you prefer.
Another interesting fact about the implementation of bits in a digital computer is that they are not absolute. If you have a particular electronic element representing one bit, that element has at any moment some particular voltage that rapidly transitions between high and low states to represent a 1 or a 0.
In theory, the transition is represented by a perfect square wave. But in practice, there are no perfect square waves. So the designers of the circuit never examine the bit during its transition state. They use the system clock to measure the bit only in the middle of the square-ish wave so as to avoid the transition period in which the state of the bit is indeterminate.
In other words we know the state of the bit only because we agree to measure its voltage during the stable part of its cycle, and never during the unstable transition. During the transition interval, the state of the bit can not be determined. It's not zero and it's not one.
In short, the answer to your question is that in theory, a bit is the smallest unit of information. But in practice, it takes a lot of electrical engineering to pretend that there is any such thing as a bit with an exact value. Bits are made of atoms; and their value is deterministic only by choosing to measure them during intervals of electrical stability.