Matthew Hutson, English 111, Brown University (1998)
"Analog" (analogue) and "digital" are both words that we hear a lot when talking about information, and to make things more confusing we hear them both describe technology and electronic information. There's analog music, and there's digital music, and they both sound the same. Well, almost. Despite this surface-level equality, analog and digital describe two completely different forms of media, in a way that perhaps is not obvious until one examines information closely. To put it simply, analog is continuous and digital is discrete.
An obvious example of this fundamental discrepancy lies in the distribution of popular music, i.e. records and CD's. Records are analogue recordings, their representation of sound directly analogous to or similar to the the original sound. When a record is recorded, sound waves imprint their form upon the media directly, creating grooves and bumps that resemble the shape of the sound waves themselves. The vibrations of the air induced by an instrument or voice travel toward a microphone, where they vibrate a membrane that directly influences the amount of current flowing through the microphone, and this current in turn pushes and pulls upon some kind of device that cuts a groove in the record as it spins. Following closely the depth of this one, continuous, spiraling groove that covers the entire face of a record, one would see a silhouetted "landscape" of peaks and valleys that vibrate the needle of your record player as it delicately rests within the moving groove. One could look at this groove closer and closer, and it would provide more and more detail, resembling the original sound wave in shape down to its individual atoms (depending upon the fidelity of the equipment.) Essentially infinite detail.
(To make this point more real, try this home experiment: Take a record no one cares about, and stick the point of a sharpened pencil into the hole. It should fit in about halfway up to the yellow paint. Now take a piece of construction paper and make a cone out of it. Push a needle out the tip of the cone so that it sticks most of the way out, and tape the cone so that it does not unravel. Now put the pencil, with the record hugging it firmly, vertical on a table, tip down, and spin it, while keeping the eraser end as close to vertical as you can manage. While spinning with one hand, delicately hold the paper cone with the other hand so that the tip of the needle rests delicately on the record. The shape of the groove should vibrate the needle, and the paper cone will amplify this vibration into faintly audible music.)
CD's contain digital information. This means that they hold all of their information in the form of 1's and 0's. A smooth, continuous sin wave, for example, is broken up into tiny discrete chunks along the x-axis (a CD-standard 44.1 thousand such chunks per second), and each chunk hold one constant value on the y-axis, easily expressible with a finite amount of one's and zero's. CD's are "16-bit", which means that each tiny sample of sound is expressed on the y-axis using 16 one's and zero's, providing 2^16 different choices. When looked at closely, a CD's representation of a sin wave is really a very small set of "stairs" going up and down along the shape of the perceived continuous wave. Thus while under normal conditions, one cannot tell an immediate difference in sound quality between a CD and a record (except for the record's characteristic "cracks and pops" versus the CD's maticulate cleanliness), stereophiles argue convincingly that records sound "warmer" than CD's, a result of their close relationship with the original voice or instrument recorded. Cracks and pops, usually the result of dust on the record, detract little from the very real-sounding analog audio experience. This slight background noise is a small price to pay for a much higher level of accuracy. On certain analog musical recordings, one can hear the musician breath between notes.
Now what about tapes? One's first guess would be digital, because its information can only be read with an electronic device, eh? Well, its representation of sound may be somewhat more abstract and inaccessible than the tangible peaks and valleys of a record groove, but they too have infinite resolution. They store information not in independent little boxes or discrete chunks of data on the ribbon, but rather a continuous distribution of electrons, or charge. Move a single electron, and the sound is different. Move one electron on a CD, and this matters little to the numerous surrounding electrons that help make up one flat chunk of data representing a one or a zero. Just like on records, the data on tapes changes and decreases in sound quality with each generation of dubbing.