Interstellar Record Album

golden recordOne of the cool things that happened in 2013 is that Voyager 1 has left our solar system. This time it was really, for sure, no kidding! There have been some previous occasions where it left, but this time we really mean it.  (Truth is, it’s still way inside the Oort cloud, so in some sense it’s merely left the city for the ‘burbs.)

Say rather that Voyager 1 no longer flies in skies affected by the sun. The heliosphere, the giant fart bubble around our solar system, is filled with our sun’s gassy emissions. Outside that bubble is the galactic ass gas of a billion other suns. Voyager 1, for the first time in human history, samples farts not our own.

It got me thinking about our interstellar golden record: Earth’s Greatest Hits!


Voyager: our message bottle.

This is not a one-million-sold golden record for the wall. This platter is our message to the stars, our message in a bottle tossed into an unimaginably vast sea. One thing I find very cool about our record is that it is an analog recording. Even the images on it are laid down in analog.

Voyager 1 & 2 both carry a 12-inch metal phonograph record complete with instructions and a stylus to play them. A committee chaired by Carl Sagan selected 115 images, a variety of Earth sounds (natural and man-made), greetings in 55 languages and a selection of music.

The thing about an analog recording is that it’s a physical chain of links directly connecting you back to the original source. That’s not true with a digital recording.

Let’s consider a recording of a singer, starting with the singer’s vocal chords. The physical (analog) vibrations cause matching physical vibrations in the air column of the singer’s mouth and throat (and nasal passages).

singer and microphone

From throat to air to mike to electrical waves.

Importantly, there is a physical and proportional connection between the singer’s body and the air. The forces applied by the singer affect the air directly and proportionally. It’s as if you grabbed someone’s hand and shook it. You can shake fast, slow or any speed in between. You can shake with little movements or large ones (or anywhere in between).

Assuming the other person goes along with all this shaking, their hand follows yours in the exact motion. Thus, you transmit the vibrations to the other person. (In the audio world, shaking faster would be like higher pitched sound. Larger movements back and forth would be like louder sound.)

So the singer physically “pushes” on the air. The air vibrations travel like waves in water to the microphone where they physically push on some element in the mike that converts the physical force to electrical force. This transformation is also proportional. Faster air vibrations result in faster electrical vibrations; larger (louder) air vibrations result in larger electrical vibrations.


Visible sound waves!

If we were able to see the electrical signal (say on an oscilloscope), it would look like the sound we were hearing. We would be able to see the direct correlation between the electrical vibrations and the sound vibrations.

Ignoring deliberate alterations done to the electrical signal by audio engineers (adjusting bass versus treble, for example, or adding reverb), the next key transformation occurs when the electrical vibrations are converted to magnetic variations on tape. Again the changes are proportional, and again, if we could see the magnetic patterns, they would match the sound vibrations.

So in a very real sense, the singer’s voice pushes the air, the air pushes the microphone, the microphone pushes the electricity, and the electricity pushes the magnetic tape. The singer directly affects the tape recording, somewhat as if you stuck your palm in some freshly poured  concrete.

studio tape deck

Studio tape deck.

As the journey progresses, the original tape recordings are “mixed down” to a “master” that will be the source of the published recording. In this case, let’s say that will be a vinyl record album.

During the mixing process the magnetic vibrations are converted back into electrical ones, deliberately altered in various ways, mixed with other signals, and then put back to tape. In all cases, the physical chain of proportional effect remains. The final master still, in some sense, is still directly connected to the singer.

Ultimately the magnetic vibrations in the final mix drive a machine that cuts grooves in a master record. The sound vibrations become physical vibrations cut into those grooves. For the first time in the process, the sound waves are actually visible. You can (with a microscope) view the waves cut into the sides of the groove (in a stereo recording, each side is one channel).

record cutter

Cutting a record.

The record master is pressed to a physical negative with ridges instead of grooves. This is pressed to a positive, which is used to make multiple negatives, which are used to press the actual vinyl records.

The intent is to preserve the original master cutting, but also to make final vinyls that are as close to perfect copies as possible.

As some point someone plays the record. The stylus riding along the grooves reacts to the frozen physical sound waves and converts them into electrical signals (ideally identical to the final mix signals). These electrical vibrations generate magnetic vibrations in the speaker coils, which results in the speaker “cone” moving back and forth.

Extreme close up (200x) of three record grooves. You can see the sound vibrations in the groove walls!

Extreme close up (200x) of three record grooves. You can actually see the sound vibrations in the groove walls!

That pushes the air, creating sound waves of the singer’s voice. Those sound waves move through the air to your ear where they become physical movements inside your ear. Your brain interprets these movements as sound.

You hear the singer’s voice.

And you hear it at the end of a chain of forces, some links physical, some electrical, some magnetic, that directly connects you back to the singer. In some very real sense, the push the singer gave the air is the push you feel in your ear.

None of that is true with a digital recording. There sound vibrations are converted to numbers. In the extreme case, a digital microphone might turn air vibrations into electrical vibrations just long enough to turn those into numbers.

Modern digital recording is so advanced now that all mixing and editing can be done digitally without ever converting the sound back into analog vibrations. Even the tape recording can be digital, just numbers on tape.

The "grooves" just contain digital data: ones and zeros!

The “grooves” on a CD just contain digital data: ones and zeros. Not visible sound!

If the recording is put to a CD, it remains a stream of numbers until the final stage in the CD player where it’s converted back into electrical vibration to drive the speakers or headphones (or ear buds).

While this insures no conversion losses all during the recording and publishing process, it does effectively disconnect the listener from the singer.

In our highly digital world, some may not be familiar with the term or concept of “generations” when copying a recording. One issue with analog recordings is that each link in the chain, each conversion, alters the recording, even if only very slightly. Think of what a photocopy of a photocopy of a photocopy looks like.

On the other hand, once something is digital, all copies are exact, nothing is altered. Think of a sheet of paper with a set of numbers on it. That sheet can be stained and creased, but if you copy the numbers to a new sheet of paper, you have a pristine copy that is absolutely identical to the original.


Bon Voyage, Voyagers!

Think of it! We little earthlings used our hands and throats to push on our air to make music and greetings. We used our technology to freeze those sound waves on a metal disk we put on our tiny craft, a wee voyager sent off on a journey to a deep, dark, unimaginably huge sea.

Now,  after almost four decades, our hopeful message reaches the last wisps of home — the first time our grasp has reached this far. Looking back, all the world is just a single bluish pixel, a handful of the sun’s photons reflected from our surface. It took them over 17 hours to make the trip!

Our sounds, our greetings, our music, our images: tiny waves, our timorous and bold hello to the universe!

About Wyrd Smythe

The canonical fool on the hill watching the sunset and the rotation of the planet and thinking what he imagines are large thoughts. View all posts by Wyrd Smythe

8 responses to “Interstellar Record Album

  • reocochran

    I am very glad that you gave us the details of the message that Carl Sagan and his team of wonderful scientists and researchers compiled! I also am so happy that our Voyager left this solar system. I had noticed a short news report on this and was pleased. We are not the center of the universe and I believe we are not alone! (Well, I HOPE we are not alone!) Smiles, Robin

    • Wyrd Smythe

      I hadn’t realized how interesting that Record Album To The Stars was until I started reading the details at the NASA/JPL website. I’d always wondered about some things, such as how any aliens would be able to understand how to play the record. Turns out they included, not just detailed symbolic instructions, but even included a stylus for playing the thing!

      And as my post points out, the thing about an analog recording is they’d be able to see the physically scribed data in the record grooves. That, plus the visual instructions, should make it a snap for them.

      I, likewise, hope we’re not alone:

      There is some thought recently that life might be extremely rare, and it’s possible we’re alone in this galaxy. If that’s so, we’re effectively alone, since the space between galaxies is just too vast (and increasing every moment). I did a piece about this if you want more details:

  • The Color of Lila

    Huh. I wonder if advanced aliens who come across Voyager could somehow use this tech to get even more info than we ever imagined:

    Certainly… they could find Earth… or what’s left of it….

    • Wyrd Smythe

      From the article, it sounds like it’s a technique for effectively reversing a broadcast signal based on analysis of its wavefront. If it can be done in real-world conditions (assuming I’m understanding what the article suggests), you could send a narrow-beam signal back to the source (without having to know the exact position of that source — that’s the part that’s kind of interesting).

      As for the Voyager record, our position in the galaxy is clearly indicated by the “drawing in the lower left-hand corner of the cover [which] is the pulsar map previously sent as part of the plaques on Pioneers 10 and 11. It shows the location of the solar system with respect to 14 pulsars, whose precise periods are given.”

      Several science fictions authors have suggested announcing our position in a possibly hostile galaxy may not be the smartest move, but for good or ill, we’ve given “them” a good map right to us. Whether they show up to find a long-dead civilization is an open question!

  • Causal Systems | Logos con carne

    […] second causal system is similar, and I’ve discussed it in detail before — analog music recording, from musical instruments and voices to reproduced sound coming from […]

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