Roberto Trotta on the Big Bang sound fossil

The following extract was taken from an interview with theoretical cosmologist Roberto Trotta published in Collpase II :

C: Another line of evidence is indicated by your work on accoustic oscillations of the early universe which are 'frozen' into the fabric of matter - a sort of primordial 'sound fossil'.

RT: Yes these acoustic oscillations are, in a way, a natural fossil. The relevance of the sound waves of the early universe in general for cosmological parameters is that it's relatively simple to calculate, because the universe was fairly young, and these density fluctuations which eventually grew to galaxies were still very small - actually one part in a hundred thousand. So they were so small that we can calculate them with very high accuracy, and we can follow their evolution up to the point where the CMBR was released , very accurately. And so from this we can confidently infer several properties of the time, for instance how much dark matter there was, how much visible matter there was, what were the characteristics of the seeds, how the seeds were sprinkled with scale, whether there were more seeds on small scales, on large scales, or whether they were uniformly sprinkled on all scales and so on. These sorts of things can be inferred from sound waves in the CMBR, because we know the physics very well. And so it's a nice spot between the very high energy physics of the very beginning, which we don't fully understand, and the messy, non-linear physics of gravitational collapse and evolutionary structure that we do understand, but which gets difficult to follow because it gets very complicated, as you can see from the filamentary structures you obtain through the computer simulations we discussed.

C: How do you go about reading these 'recordings' of the Big Bang?

RT: We saw that the CMBR is very homogeneous because of its cosmological origin. But now we have very sensitive detectors, telescopes and satellites that measure the background radiation to a very high degree of accuracy. And if you look carefully enough, you will see that this CMBR is not perfectly homogeneous; it has temperature differences in it. So if you look with your telescope in this direction, we see a slightly colder spot, if we look in that direction we see a slightly hotter spot. We can build a map of the sky, showing the temperature distribution of the background radiation. In order to measure the differences between the hot and cold spots with your telescope you need a sensitivity that's equivalent to the sensitivity you'd need with an optical telescope to see a mouse walking on the moon from the earth. So it's very tough. The guys who first did it in 1992 got the Nobel prize in 2006. These fluctuations you see in this map are the sound waves from the early universe, that's exactly what they are. When you throw a pebble in a pond you've got waves that go out in all directions; if you throw many pebbles in a pond you get a nice superposition of waves. In our case the pebbles were quantum fluctuations in the early universe, and they got frozen in at the moment the image was produced, and this is what we see - we really image them with our telescopes.

C: Calling them 'sound waves' is not just a figurative way of speaking, then?

RT: No, it's a technical definition: they're compression waves. The universe at this point was a plasma, that's a hot gas of electrons and protons, seperated by the temperature because the temperature was so high. So those were really accoustic waves, just like the waves in the air now as I speak, only they were travelling in the primordial plasma. And we can see them, as we can see in this map: it's real, it's been predicted and we find this fantastic agreement with our models...

Unabashed sound

I went down to the recent collective listening event at the ICA. The idea, that a group gather (historically in a gallery but it doesn’t have to be one), sit and listen carefully to an extended audio piece at reasonably high volume and afterwards discuss the work and their responses to it, is one that has caught my imagination so I wanted to write something about it here. The event’s organiser: theorist and music critic Mark Fisher, outlines a genealogy of his thinking on collective listening here.

The piece or ‘audio essay’ as it was termed on the night was The Latecomers (1969) by Canadian pianist and radio artist Glenn Gould which is the second part of his Solitude Trilogy and focuses upon life in Newfoundland . The work begins with the overwhelming noise of crashing waves and the North Atlantic Ocean, in various degrees of agitation, is present for the duration. At the forefront are fragments of speech: at least 10 Newfoundlanders, mostly male but of differing age, discuss their lives and the place they live them. There are amusing anecdotes, fond memories, childhood songs, lucid descriptions, personal histories, and lots of ideas. Ideas on politics, economics, change, community, modernisation, urbanisation, leaving and isolation. Although these ideas are often conflicted there didn’t appear on first listening to be any dialectical ordering of the fragments. What slowly emerges is a sense of the singularity of Newfoundland as an environment, and a distant intimacy with those who live there. And despite its focus on Newfoundland at a very specific historic juncture – the period in the 1950s and 60s when the provincial government, keen to reduce the cost of providing dispersed public services, encouraged outport communities to urbanize - the piece has universal signification in its treatment of being-in-the-world. The way we relate to place; what it means to love the place you live and how we relate to the past when building a future.

The Latecomers is a challenging listen: the immutable ocean often masks the spoken content and at times, when the voices are contrapuntally posed, a practice pioneered by Gould, it’s nigh-on impossible to make out what’s being said. In addition, as Fisher says in the piece linked to above, simply “being asked to concentrate on something for such a sustained length of time poses a challenge.”

Listening together helps overcome this challenge in a number of ways. First, and simply, the fact that someone else has chosen this work, considers it worthy of close listening, and has been troubled to organise, promote and deliver an event to present it, coupled with the presence of numerous others, leads to nervous anticipation, a build up towards something assumed special. Even before the playback, you’re ready to listen. Second, the social rules associated with public consumption help create conditions commodious to concentrated listening. For example, there were no rude disruptions from mobile phones, how many people turn their phones off when listening at home? Third, listening with others aids concentration: although Gould’s work was the dominant stimulus in the room, there were extraneous sounds, audible responses to the piece: chuckles, deep inhalations and so on. When not affected in the same way I found myself, determined not to miss out again, return to the work with increased concentration. In this way listening with others increased my individual receptivity.

Finally, listening together means you can talk about it afterwards. Feelings and ideas insinuated can be collaboratively teased out, elaborated and examined. As Lena points out in her review , the day’s discussion floundered a bit on the meaning and emotional import of Gould’s work. Lena’s suspicion that people were inattentively hearing as opposed to actively listening is well founded - listening is an acquired skill and our culture ill-equips us for it. Future collective listening events will give attendees a chance to develop and hone listening skills on challenging material, with practice we’ll get better at listening and better at talking about the wealth that it brings.

Listening to listening

In her book Deep Listening Pauline Oliveros provides a simple and useful distinction with which to begin thinking about listening:



"To hear is the physical means that enables perception. To listen is to give attention to what is perceived both acoustically and psychologically."



Here, rather than being synonymous terms, hearing and listening differ markedly. The first describes an automatic response to external stimuli: the conversion of physical sound waves into the neural signals that result in raw sensation. As such it's continuous, unconscious and occurrs whether awake, drowsy or in deep slumber. The second involves actively directing conscious attention towards sound, its acoustic properties, and the meanings, ideas and emotions embedded there-in.



This distinction finds a metaphysics in Bergson's subtractive model of perception, which is expertly elucidated by Meillassoux during the course of his essay on Deleuze for Collapse III. Here matter is thought as a vast collection of images whose interaction is governed by the constant laws of nature. Accordingly perception is the relation between an image or set of images and the unusual image that is the human body. The relation is one of impoverishment, as Meillassoux puts it:


"The living is not primarily the emergence of the power of interested choice, but the emergence of the power of a massive disinterest in the real to the profit of certain rare segments of the latter, which constitutes the whole of perception."



Perception reduces the infinite complexity of the material world to a few 'rare segments' via two radically discriminatory selections, the first made by the body, the second by the mind. In audition, the body effectively 'chooses' to hear certain sounds - those of a particular amplitude and frequency, and not others - those that fall outside the perceptible ranges. The 'physical means' that comprise hearing for Oliveros omit more sounds than they permit.


But what happens to those sounds we do hear? Heard sound provides the material for a second subtractive selection. This choice is made by consciously attending to a specific sound or group of sounds, again at the cost of others. The 'Cocktail Party Effect' theorised by researchers organised around CRESSON is an everyday example of these choices. A soiree attendee's attention is drawn to a voluble exchange occurring on the room's other side; they actively choose this conversation as the object of listening and the general clamour remains just heard. The example speaks of the localising power of concentrated listening, the observable fact that it can ignore so much sound.


The 'Profit' accrued by the diminutive bit of reality listened to is, for Bergson, generated by the labour of memory. It's memory that guides our decision on what to listen to. Let's say for example that the conversation our lonely socialite tunes-in to involves his ex-girlfriend. She's openly expounding her theory of 'where it all went wrong'. Here it is the listener's personal history that has drawn him to these sounds in the first place and furthermore it is his memory that enables him to understand the language of what is being said. So where the first choice, that of hearing, is biologically determined and as equally distributed as the human body, the second, that of listening, is socio-culturally determined and as diverse as world cultures are. Cross-cultural Listening practices differ in two ways: firstly, by the listened to sounds: different peoples consider different sounds significant; and secondly by the meanings attributed to those sounds.