A Journey in Time
A talk about time in physics, philosophy and music, given as an introduction
to a Tabla solo in Teen Taal performed by my teacher Ustad Babar Latif Khan,
accompanied by Ustad Surjeet Singh on Sarangi.

This talk and the Tabla Solo were within the first part of
a Music as Medicine event which I organised with
Damien Mahoney and Joanne Burrows, for my teacher.

The second part of the event consisted of two Ragas,
Bageshree in Jhap Taal and Mand in Dadra,
performed by Jonathan Mayer on Sitar, Surjeet Singh
on Sarangi and Babar Latif Khan on Tabla.

The event was held on the 4th of December 2019
at The Anthony Burgess Foundation in Manchester.

Sound: Damien Mahoney and Simone Walsh.
Videography: Marsha Balaeva.
Photography: Anna Joos Lindberg and Alexander Dodgson.
Musical interlude: George Duerden.

Both music and cosmology have to do with our origins.

Music is the art of time and cosmology is about the timeline of the universe.
For both, time is a central question. Today I will explore the concept of time from different perspective.

Most of the ideas I am going to present are originally from the book "The Order of Time" by Carlo Rovelli, and "Pourquoi la Musique?" by Francis Wolff. More details can be found in these two amazing books, as well as in the list of references given at the end.

Everywhere there is people, there is music. The most ancient known musical instruments are bone flutes from the Palaeolithic era. The oldest known engravings are zig zags on a shell. A 500,000 years old artefact attributed to Homo Erectus. Since Shells also serve as musical instruments, music possibly appeared at that period too.

Music touches our origins. One purpose of religious rituals, is to re-enact the stories of the gods, creators of the world, and to communicate with them. In these rituals, music and dance are essential, as a magic gateway to the gods.

For instance every Thursday nights at the tomb of Nizamundin in Delhi qawallli songs are chanted throughout the night, to connect with Allah.

Another example in India is Maha Shivratri happening once a year. At this occasion people dress as the god shiva and perform sacred dances. A large statue representing Shiva can be seen at the CERN in Switzerland. The plaque says: "Shiva symbolises 'Shakti', or life force, in the Hindu Trinity. He is the creator, the sustainer, and the destroyer. The Nataraja in Ananda Tandava shows him dancing the universe into existence, sustaining it with His rhythm and dancing it to extinction. Creation is sparked by the vibration of the drum in the right hand. The aureole represents the cosmos, the sun, moon and stars revolving in perpetual and fiery motion."

Ancient myths are based on natural cycles, such as the cycles of the seasons and celestial bodies.

The structure of Indian music is based on time cycles called Talas. Teen Taal, the cycle for the Tabla solo tonight is in 16 beats. There are four phases to the full cycle. This structure actually reflects the structure of Time in the Hindu mythology according to which the universe is created and destroyed cyclically. Each cycle being made of four subsequent phases. With a complete cycle, a Maha Yuga, lasting for 12,000 years.

In Europe and in India, philosophy emerged when people refrained from using myths and gods to explain nature and human existence. Then, science appeared when philosophy adopted the language of mathematics and the scientific method, based on measurement, falsification and reproducibility. To enter science, let me read a quote from Blaise Pascal, a contemporary of Galileo Gallilei and Isaac Newton.

"Let man then contemplate the whole of nature in her full and grand majesty, and turn his vision from the low objects which surround him. Let him gaze on that brilliant light, set like an eternal lamp to illumine the universe; let the earth appear to him a point in comparison with the vast circle described by the sun; and let him wonder at the fact that this vast circle is itself but a very fine point in comparison with that described by the stars in their revolution round the firmament. But if our view be arrested there, let our imagination pass beyond; it will sooner exhaust the power of conception than nature that of supplying material for conception. The whole visible world is only an imperceptible atom in the ample bosom of nature. No idea approaches it. We may enlarge our conceptions beyond all imaginable space; we only produce atoms in comparison with the reality of things. It is an infinite sphere, the centre of which is everywhere, the circumference nowhere."

We live in a gigantic space, which has no centre. Moreover, when we look at remote galaxies, they appear to recede. The further away they are, the faster they move away. Since the Big Bang, 13 billion years ago, the universe is expanding like a giant rubber band.

In 1998 a key observation was made which tells us the universe appears as if it is dominated by a mysterious fluid with negative pressure. A form of energy, dark energy, which makes things accelerate away from each other, instead of toward each other. If dark energy is constant or unstable, the patch of the universe to which observers will have access in the far future will be extremely diluted and cold, maybe empty. However, if dark energy slows down, the universe will become denser and denser ending in a big crunch.

The main focus of our research group in Manchester is the study of the relic light, called the CMB.

The CMB is the most important observable in cosmology. It tells us about the content and the history of the universe. The current picture is that standard matter is only a small fraction of the universe, amounting to no more than 5%. 95% is in the form of dark energy and a dark matter, a yet unknown form of matter. So, we are still mostly in the dark.

Nevertheless, the last couple of years have seen two promising major breakthroughs.

These breakthroughs are the first measurement by the LIGO interferometer of gravitational waves emitted by merging pairs of black holes. And the second breakthrough is the first picture of matter falling into a black hole at the centre of the galaxy M87.

The first time the existence of objects such as black Holes was proposed was in 1799 by the French mathematician and astronomer Pierre-Simon Laplace. The idea is simple. Given a massive body there exist a minimal velocity that allows to escape from the gravitational field. People already knew that the speed of light was finite and even had a quantitative estimate. Laplace then computed the size and density of an object for which the escape velocity would be the speed of light, using Newtonian mechanics.

For Newton, space and time are absolute, in the sense that they exist without event and without things. When Laplace was thinking about black holes, he was thinking within this framework of space and time.

But in 1905, Einstein understood that it is the speed of light that is absolute, not space and not time.

This was a revolution and the birth of the theory of relativity. Suddenly, "universal time has shattered into a myriad of proper time" (Rovelli).

If I set on a long journey in a fast space shuttle and you stay here, i will be younger than you when I come back. In addition to my journey in space, I will have travelled in time, into your future.

Can I travel into the past?

No, because a future event can not be the cause of a past event, this is the principle of causality. The only way I can travel to the past is with my mind.

Our brains, with our memory, is a time machine to return to the past. This is the Madeleine of Marcel Proust or the perfumes of Andy Warhol who once wrote: "I switch perfumes all the time. If I've been wearing one perfume for three months, I force myself to give it up, even if I still feel like wearing it, so whenever I smell it again it will always remind me of those three months."

Aside from psychological time travel, traveling into the past is impossible.

Following the discovery of special relativity, Einstein discovered General Relativity. General Relativity combines space, time and matter into one equation. According to this equation, gravity is the curvature of space-time caused by matter. Space and time are distorted by the presence of matter.

Hence, Laplace could not have had the correct full picture of a black hole. There is indeed a special distance from the centre of the black hole called the event horizon, and at the event horizon the escape velocity becomes larger than the speed of light. But there is more to a black hole.

To put it in a dramatic way, space-time itself is falling into the black hole at a rate that can not be beaten by light. A black hole is like a waterfall of space-time.

So what happens to time near a black hole?

Say you stay here and i go to the black hole. First, because of special relativity, your time will pass faster than mine. And on top of this there is the effect of gravity near the black hole.

Gravity too slows down my time with respect to yours. In fact you will see me slow down and finally you will have the illusion that I am stuck at the event horizon forever.

While, in reality, I have continued progressing towards the centre of the black hole, faster and faster.

"how long is forever?" asks Alice, "sometimes just one second" replies the White Rabbit.*

Although Galileo, Newton and Einstein have shown us how we should think about the passing of time, modern science is still unable to answer what is the source of time. To understand Time, we need thermodynamics.

All the physical laws that we have found so far are time reversal invariant. They say that everything that happened from Monday to Wednesday could also have happened reversely, from Wednesday to Monday.

There is only one law that makes a difference between the past and the future, It is the second law of thermodynamics. It says that entropy increases.

Entropy is the physical quantity that measures disorder. So, nature always evolves towards more disorder.

Thermodynamics is the science of heat, and the theory of heat, was established based on the study of steam engines which were at the centre of Manchester socio-economical fabric. The city of Manchester remembers this history with a statue of the father of modern steam engines, James Watt on Piccadilly square.

And today, we also have a special opportunity to remember this history. We are now in the same room that was hosting some of Watt's steam engines during the industrial era, surrounded by the same red bricks.

What does it mean that entropy must increase?

Throw fifty dice and say you can only tell whether the number you get are the same or different.

Fifty dice showing only the same number, like just ones. Or fifty dice showing different combinations of numbers. But the exact numbers do not matter.

There are many more configurations with different numbers, than configurations with same number. Because of this, we say that the entropy of the dice showing different numbers is greater than the entropy of the dice showing the same numbers.

So here is how time passes: if we start in the configuration with the same numbers, the low entropy state, then at the next throw we will end up with the configuration with different numbers, the large entropy state. When we went from the same numbers to different numbers, time has passed.

Had we started with different numbers, we would generally end up again with different numbers. Since we are not sensitive to the particular numbers on the dice, we find that nothing has happened. Time hasn't passed, because entropy can not increase anymore.

What make things happen is the low entropy of the past. For things to happen, we need sources of low entropy. Entropy is disorder, and disorder is caused by heat, so, heat sources are sources of low entropy. The sun is a source of low entropy.
Each hot photons the sun sends us is absorbed by the earth and turned into ten, or many, colder photons. There is only a few ways for one hot photon to be hot, while there are plenty of ways for ten cold photons to be cold, so entropy increases, plants grow, animals evolve.**

If entropy is low in the past, then the universe should evolve towards a state of maximum entropy, the state of thermal equilibrium. There will be no more sources of low entropy to make things happen. Technically time can stop.

So we must appreciate that we now live in a very particular and ephemeral stage in the history of the universe.

Quantum fluctuations in the early universe have created large potential wells, in which clouds of hydrogen and helium have collapsed and formed stars. Our sky is now full of galaxies, stars and planets.

But galaxies, stars and planets do not keep forming again and again. The giant clouds of primordial hydrogen and helium can only collapse once.

In the far future, only black holes, photons and electrons may be left in the universe. Eventually, black holes will evaporate, leaving the universe in a homogenous, thermal bath of elementary particles, in a state of heat death.

To not leave this discussion on a pessimistic note. Let me add something fun to think about.

If i throw fifty dice, i am sure I will get different numbers on the dice. But this is true only in a statistical sense, as some very rare times, I will get the same number on the fifty dice.

Even if the universe is in thermal equilibrium, there are inevitable thermal fluctuations, which always occur, all the time. Thermal fluctuation are like throwing the fifty dice again and again.

So, over very long time scales, thermal equilibrium should still allow for special configurations. For instance, the configuration where space-time finds itself in a singular state, like the big bang. And from such a low entropy state, a new interesting story can unravel.

A long time ago, Ludwig Boltzmann also thought about this sort of ideas. He asked himself questions similar to the following: "what is the most likely way to explain reality, assuming the world started from the heat death state?" The answer is that the universe contains one single brain who is dreaming our reality.

This type of ideas are obtained by extrapolating current theories and do not belong to the realm of experimental science. I think they are only interesting from a philosophical view point because they make us reflect on the nature of reality, a fun thing to do.

The multiverse conjecture is in the same class of ideas, as well as another lesser known idea called the simulation hypothesis, which also tells something interesting about the future. It was proposed in 2003 by Nick Bostrom.

He says that one of the following assertion is true:

1) Almost all civilisations go extinct before they reach technological maturity.

2) All civilisation that reach technological maturity lose interest in running simulation about their past.

3) We are almost certain of living in a simulation.

Later, I can tell you why if one and two are false, then three must be true.

We have seen that the passing of time is directly linked to the increase of entropy, to more disorder.
The notion of order depends on what I am paying attention to, for instance just seeing the same number on the dice.

So it means that it depends on what I ignore, on a particular blurring determined by how I interact with the world. Hence, the notion of entropy is also relative. According to Carlo Rovelli: "causality, memory, traces, the history of the happening of the world itself can only be an effect of perspective. [...] inexorably, then, the study of time does nothing but returns us to ourselves." end of quote.

We generally feel well in an environment that we can understand, which is ordered and relies on commonly accepted rules and beliefs. Laws, religions, science and arts all serve the purpose of attempting to create such an environment, the illusion of a tamed world.

What is the world made of?

"The world as we see it, seems to be made of things and events. [...] the difference between things and event is that things persist in time; events have a limited duration. A stone is a prototypical 'thing': we can ask ourselves where it will be tomorrow. Conversely, a kiss is an event. it makes no sense to ask where the kiss will be tomorrow." (Rovelli)

For the rest of the talk I now turn to music and try to summarise the ideas of Francis Wolff.

Music gives us access to a world of events without things. A world of sounds. It represents the world within a temporal order, without space. (Wolff)

No space, no things, just events.

In music this is possible without the need of further sense experience than hearing.

And even without our hears, we can hear music in our head, like Beethoven who by the age of 44 was almost completely deaf and went one composing some of his master pieces entirely based on sounds from his imagination. Music, the art of sounds, is the only art that needs only time and nothing else.

Thus we say that music is the art of time.

So, what does music do to time?

When I listen to a melody, if I could be in the present, by focusing mind like an experienced buddhist nun, I would not hear music. Music in the present can not be music.

Music only makes sense if I have the traces of the past sounds that are still present in my memory. So, music is a fusion of musical notes, which have appeared and continue to appear, in a certain order and are all present at the same time inside my mind.

What about the future?

When we listen to music, we anticipate what is going to happen.
Take the sense of rhythm. We do not have an organ in our body that plays the role of a clock, nevertheless musicians are able to keep the beats just as well as our electronic metronomes. This implies that Listening to music is also taking a bit of the future into the present.

"Music makes the fusion of the past and the future into an elongated present." (Wolff)

My final point is that in music, our relationship to time emerges in a similar way as it does for an historian or a cosmologist.
All the events that have happened explain the events that are happening. Moreover, we are able anticipate the events, the sounds, that are going to happen, and once they have happened they appear to us as necessary.

Music rationalises our experience of time, relying on three aspects: permanence, causality, and interaction.

To understand something that is happening, I need first to be able to recognise the object throughout the processes that are affecting it. In this talk, I need to make sure that whatever I am saying, you can relate it to our subject, "Time" and Indian Music. There is a guiding thread. I do not suddenly talk about why I would want to become a cat.

We need guiding threads to understand the world, some form of permanence. Without them, we are lost.
In music, an example of a guiding thread, is what Francis Wolff calls the the "master sound". This is a sound that occurs either constantly or that keeps coming back. All the other sounds in the composition relate to the master sound, interacting with it. In Indian classical this is for instance the sound of the Tanpura.

The second aspect of rationalisation by music is causality.

To understand a series of events happening, I need to know which one has caused the other. Causality is created between sounds due to several processes.
Rhythm is one of them. I hear this sound now, because I heard that other sound exactly two beats earlier. That sound is the cause of this sound.
There is also the musical scale. A musical scale is a set of sounds that go well in a sequence, which we feel a related to each other in a causal way.

Finally the third aspect of rationalisation is the interactions between simultaneous sounds.

As Francis Wolff says: "When the three notes of a chord are played together, we do not hear them simultaneously, but their mutual interactions in a unified way, according to the laws of harmony."

Through permanence, causality and interaction, music, makes us understand a possible world, a world made of events without things, a purely temporal world, replacing for a moment the chaos of the real world, by a tamed world of sounds.

In the philosophy of Carlo Rovelli, relations between things are more important than the things themselves. Events, Relations and interactions maybe seen as more real than the things that are interacting.
"The world is made of events, not things. The world is made of network of kisses, not stones." (Rovelli)

Then, music must bring us closer to reality.

"A song, as Augustine observed is the awareness of time. It is time. It is the hymn of the Vedas that is itself the flowering of time. In the Benedictus of Beethoven's Missa Solemnis, the song of the violin is pure beauty, pure desperation, pure joy. We are suspended, holding our breath, feeling mysteriously that this must be the source of meaning. That this is the source of Time. Then the song fades and ceases.

'The silver thread is broken, the gold lantern is shattered, the amphora at the fountains breaks, the bucket falls into the well, the earth returns to dust.'

And it is fine like this. We can close our eyes, rest. This all seems fair and beautiful to me. This is time." (Rovelli)

Boris Bolliet

* A Lewis Caroll quote used by Carlo Rovelli in The Order of Time.

** This example is developped in more details in Penrose's and Rovelli's books.

References and further readings:

- Pensées, Blaise Pascal, 1670.

- Physics and Reality, Albert Einstein, 1937.

- Images and Symbols, studies in Religious symbolism, Mircea Eliade, Princeton University Press, 1991.

- A Comparative History of Ideas, Hajime Nakamura, Motilal Banarsidass Publishers, Delhi, First Indian Edition, 1992.

- The Shape of Ancient Thoughts, Comparative Studies in Greek and Indian Philosophies, Thomas Mc Evilley, Allworth Press, New York, 2002.

- Revue de métaphysique et de morale, 72, 2011/4, Francis Wolff.

- Music and the ineffable, Vladimir Jankélévitch, Princeton University Press, 2003. (First publication in French 1961.)

- Pourquoi la musique? Francis Wolff, Fayard, 2015.

- Seven Brief Lessons On Physics, Carlo Rovelli, Allen Lane, Penguin Books, 2014.

- The Order of Time, Carlo Rovelli, Allen Lane, Penguin Books, 2018.

- The Emperor's new mind: Concerning Computers, Minds and The Laws of Physics, Roger Penrose, Oxford University Press, 1989.

- The five ages of the universe, Fred Adams, Gregory Laughlin, Free Press Publishers, 1999.