The Golden Record
“To the makers of music — all world, all times.”
Hand-etched on the un-grooved portion of two phonograph records flung into deep space, carrying a heartfelt time capsule from mankind are these words. They contain (almost) everything that has been deemed dear to us: sounds of laughter, images of a mother nursing her baby, and folk music. There are no depictions of war and poverty, but there are recordings of greetings being spoken in over fifty languages, ranging from “Peace.” to “We are thinking about you all. Please come here to visit when you have time.” In essence, it sings a simple message: Hello. I hope you find this and by extension, us.
The time capsules in question are the golden records perched atop Voyager 1 and 2, launched by NASA in 1977. Their mission was a flyby of the Jovian planets and their moons, after which they were to embark on a journey into interstellar space, never to return. This made the probes the perfect vehicles to carry a message for extraterrestrials.
Mimicking the Pioneer plaques (sent with Pioneer 10 and 11) on their covers, but massively increasing the amount of information one could send, the golden records were one of their kind.
However, this was not the first time such an ambitious and far-fetched endeavour was undertaken. We have been communicating to the supposed emptiness of space since we gained the ability to do so, starting with the Arecibo Message: a frequency-modulated radio message carrying basic information about humanity and earth transmitted towards the globular cluster Messier 13 in 1974.
But what information does one convey in such messages? More importantly, how is that information conveyed to an intelligent extraterrestrial civilization which may in fact be nothing like what we have imagined aliens to be?
Carl Sagan, a planetary scientist closely involved in the creation of these messages, comments upon this in his book ‘Murmurs of Earth: The Voyager Interstellar Record’: “So if it is possible to communicate, we think we know what the first communications will be about: They will be about the one thing the two civilizations are guaranteed to share in common, and that is science. The greatest interest might be in communicating information on music, say, or social conventions; but the first successful communications will in fact be scientific.”
This forms the heart of these endeavours. They use simple scientific and mathematical facts as a means to communicate. And there is quite a lot that needs to be communicated, starting with a set of instructions describing how the subsequent information should be received and interpreted.
For example, the Arecibo Message consisted of a continous string of 1,679 binary bits which translates to the shown image (without colour) when arranged as a grid. The number 1,679 was chosen specifically because it is semiprime (the product of two prime numbers: 73 and 23), resulting in only two ways one can form a grid using the bits. Thus, working under the assumption that a knowledge of primes and factors must be possessed by any civilization intelligent enough to intercept and interpret the radio message, we have successfully conveyed our first piece of information!
Each of the two identical golden records also comes with instructions on how to play it: on the upper left-hand corner of the cover are drawings of the phonograph record and the stylus carried with it (already positioned correctly to play the record from the beginning), indicating that it should be played from the outside in. Here, we are faced with another communicative hurdle to cross, upon which rests the communication of all quantifiable information: the conveyance of units of measurement. How does one tell the aliens that we are approximately six feet tall, or more importantly, one rotation of the golden record equals 3.6 seconds, without them knowing what a foot or a second is?
Naturally, we made use of scientific knowledge again. The time period associated with the fundamental transition of the hydrogen atom is approximately 0.70 billionths of a second, and 3.6 seconds expressed in this unit of time has been inscribed in binary around the drawing on the cover. The same has been done for the time required to play one side of the record (between 53 and 54 minutes), and other informative illustrations. Hydrogen was chosen because it’s the most abundant and the simplest of elements in the universe, increasing the chances that intelligent extraterrestrials would recognize it.
A diagram depicting the two lowest states of the hydrogen atom, with dots and lines indicating the spin moments of the proton and electron, is also given on the bottom right-hand corner, solidifying the idea that the transition time from one state to the other provides the fundamental clock reference throughout the entire process of interpretation of the record.
The cover also features a diagram that cleverly conveys our location in space using pulsars: rapidly rotating remnants of stars which generate powerful beams of radiation, sweeping across the sky (like a stellar lighthouse!) Individual pulsars spin at different speeds, making them identifiable even with very simple radio receivers. Giving the location of our sun with reference to fourteen neighbouring pulsars is a diagram on the record cover. Each pulsar is connected to the sun by a solid line. The length of the line represents the pulsar’s approximate relative distance from our sun and along each of the pulsar lines is etched the precise frequency associated with that pulsar. This however, is a 2-D diagram, and to convey the 3-D positions of all pulsars and our sun, a fifteenth solid line was introduced, with a tick mark at its end, indicating the relative distance between our sun and the center of our galaxy. Tick marks in all pulsar lines similarly indicate their relative distances as well, establishing their position (and ours) in 3-D space using simple concepts of triagulation.
An important part of a time capsule is knowing how long back it was put together, and to convey this, the record cover has a two-centimeter diameter area of uranium-238 electroplated on it. The steady decay serves as a radioactive clock, and examination of the leftover uranium along with its daughter isotopes gives the time elapsed since the spacecraft was assembled and launched.
When we come to the actual data in the record itself, everything that is sent must be a precarious mix of universal scientific knowledge and information exclusive to the earth and the solar system that can be extrapolated from said knowledge.
As Carl Sagan says in his book, “In choosing pictures, we were faced with two contradictory demands: the pictures should contain as much information as possible, and they should be as easy to understand as possible. It seemed to me that one solution would be to have on board some pictures with very little information, primarily to help the recipients understand how to see pictures.” It is also rather useful to include ‘checks’ that help confirm that one is indeed interpreting things the right way. Hence, the very first image, if properly translated and calibrated, will display a circle, which is also engraved on the cover of the record. Being an engraving, it can be perceived by senses other than vision, which is meant to give the recipients a way of comparing a photograph with an object they can touch.
The next set of photographs are rich in arithmetic, providing a kind of dictionary of simple mathematical and chemical symbols that have been used in subsequent images to convey information such as the size of a human being, the size of planets, the elements most abundantly found on earth etc. There are anatomical pictures of the human body, simplistic diagrams of DNA with its constituent elements listed out, highlighting its double-helical structure.
Silhouettes were also utilised, sometimes following a photograph of the same scene, as the high contrast made it easier to isolate different objects in a photograph and bring attention to some of them. There are multiple images of the natural world: seashells, dolphins leaping in the air, insects pollinating flowers, geographical features like islands and riversides, sunsets, and earth as seen from space.
There is a photograph of Andromeda, a galaxy which may also be visible to the extra-terrestrials, placed with a segment of the pulsar map from the cover, to hint towards the fact that it is another one of our stellar neighbours. As pointed out by Jon Lomberg, part of the team which designed the image and sound sequence on the record, “ it may be the only object in the whole package of pictures that both we and the recipients have seen firsthand.” (This image also provides a check to the “handedness” of all pictures—the recipients can compare it to Andromeda as observed by them to ensure that reconstructed images are not laterally inverted.)
There are numerous images which focus on the lived experience of humans, showcasing complex but important actions like parenting, shopping, teaching, hunting and gathering, eating, researching, driving, manufacturing, painting, walking, spacewalking and playing the violin. Of course, it is unlikely that these complicated images will be interpreted in their entirety, but a complete communication of the essence of humanity would have been incomplete without their inclusion.
By sending the same image thrice, indicating the amount of red, blue, and green in each picture, one can send coloured pictures as well. Around 20 such images were sent, the first of which is the solar spectrum. Every star has a distinctive spectrum: a continuous band of colour broken by a series of dark lines, which correspond to wavelengths absorbed by elements in the star. This tells us a great deal about the temperature of the stellar surface, the “colour” of the star, and an extensive knowledge of these spectras provides much of the observational basis for studying the universe.
Extraterrestrials with basic knowledge of stellar astronomy should be able to identify the sun as a G2 star from its spectrum (even if seen in black and white!), and from there reconstruct what the spectrum of such a star should look like in colour (and by colour, of course, we mean the portion of electromagnetic radiation visible to humans, but the absorption lines should convey that we wish to indicate something about this particular portion of the spectrum.) Using this, they can understand the concept of colour separation, and then they’ll be able to see flowers, coral reefs, jungles, deserts, snow-studded trees, illuminated buildings, and skin tones in their original colours.
As is evident from many of the images, unlike earlier messages, the information stored in the golden records is not purely scientific. The audio segment of the record features natural sounds like that of thunder, volcanoes, rain, birds, wild dogs, and crickets. It also includes the sound of the human heartbeat, footsteps, laughter (Carl Sagan’s), heartfelt greetings in over 55 languages, and a compressed version of an hour-long recording of a woman’s brainwaves as she thought about topics like love, death and civilization.
And what is a record without music in it? An eclectic 90-minute selection of music from many cultures was included, ranging from western classics to indigenous folk music.
All in all, the golden records were as complete a time capsule as we could hope to create as a species, made under near-impossible time, budget, and administrative constraints by a group of highly motivated people. The Voyager crafts are currently the farthest man-made objects, and they only move farther every second. The records secured safely upon the spacecrafts are estimated to survive for billions of years (gold being considerably non-reactive), possibly outliving all of mankind, and earth itself. If intelligent extraterrestrials ever come across them, they will witness the sombre echoes of lives that lived long ago, reaching through time with warm hands.
Of course, this hinges on the assumption that extraterrestrial civilizations are scientific creatures, given that we are using “the language of science”, but the downside of developing any language, even out of science, risks it becoming too well-tailored for us. Even if scientific knowledge is universal, who is to say that the specific set of scientific knowledge discovered and developed by us is universal? What if it is possible to build an intelligent civilization without discovering hydrogen at all?
A far more absurd assumption, however, is that these extraterrestrial creatures will be somewhat similar to us in terms of how they receive and interpret sensory input. We have transmitted images and sounds, but what if they have nothing akin to eyes or ears? It is perfectly plausible for them to navigate their world using magnetic fields, have smell as their primary sense, or have other sensory mechanisms unimaginable to us. Our attempt at communication will have been futile, in that case.
This makes the occurrence of reception and interpretation of these messages by intelligent extra-terrestrials which also share a similar notion of science and sensory input, laughably unlikely.
What then, is the real purpose of the golden records?
A contributor to the project, B. M. Oliver, said it aptly, “There is only an infinitesimal chance that the plaque will ever be seen by a single extraterrestrial, but it will certainly be seen by billions of terrestrials. Its real function, therefore, is to appeal to and expand the human spirit.” More than an exercise in communication with unknown beings, it served as an exercise in communication with our collective conscience. It allowed us to make note of what is unique to our planet: the sound of earthquakes, birds flying in the sky, a baby held dearly by her mother.
Through the golden record, we saw ourselves in a different light: not as conquerors of planet earth, but as children of it. We saw ourselves as a civilization built upon scientific knowledge, social bonds and music; a species with no companion but themselves, hurtling through darkness wielding lights of our own. Even if the gaze of no strange eyes falls upon the golden records, their creation will not have been in vain. They have already achieved what they set out to.