Time, Bodies And Binary Stars
As part of the development of We are all made of stars we had the opportunity to consult with Dr Sheila Gilheany, policy adviser with the Institute of Physics in Ireland, who has a background in astrophysics. Finding a way to share interests between artists and scientists is a process of exchange of ideas, of finding the right questions and indeed of investigating language itself. The email conversation points to Dr Gilheany’s generosity and her skill in communicating , very poetically, difficult ideas around time and space in her field.
MZ : What has amazed me in my research is the extent to which the evolution of quantum theory is written into the development of the arts, particularly in relation to ideas about bodies. I wondered how you think about the body or in fact if concepts of other kinds of bodies feature in your work?
SG: I'm not quite sure how to answer you about bodies and my work but I know I often find myself thinking about the journey that the molecules in my body have made, from atoms of hydrogen, carbon, oxygen and nitrogen formed in stars via nuclear fusion at different stages in the evolution of the star. Later these atoms were scattered as the star died and enriched the local interstellar medium, became part of our solar system. They made their way through plant life and animals into the food chain and finally ended up in my body as I ate the fruit of the earth. Eventually they will move on from my body, back into the earth and to another destination, maybe in trees, or seas and in another few billion years perhaps to a whole new planetary system and some other life form.
I have a gold ring which I wear and I love thinking that the gold atoms were formed in a supernova explosion, as a star collapsed catastrophically and were then flung widely across the universe before ending up deep underground on earth, being mined perhaps in horrible working conditions. Perhaps made into bullion, or other jewellery, re-smelted and ending up on my finger.
MZ: I love how you've answered my question, both in how you describe possibilities of corporeal connections to many kinds of matter at different stages, and in the narratives that are contained in your gold ring that point simultaneously to stories of astrophysics, politics, exploitation and intimacy - I want to make that film. The narrative you describe is spatially complex, there is a narrative structure in experimental film (and poetry) called a vertical narrative. Vertical narratives work through associations and in a film with a vertical narrative an image will lead a viewer through imagery that invites her to subjectively consider many possible tracks of thought, she can move around in time. This is very different to linear narratives which drive a viewer forward on a horizontal axis through linear time.
In developing we are all made of stars as an installation and in playing with the 360 VR content it's been interesting to try to think in terms of a spatial form or narrative structure that speaks to the kind of narratives you describe. That is, narratives that suggest different kinds of time and space. This where I become both excited and frustrated at my own inability to 'speak physics' - I wondered if you had thoughts of spatial forms that speak to telling the story of your gold ring?
SG: The timescales around the formation of gold and the other heavy elements are both incredibly long and short and it connects with other strange relativistic concepts.
Time is a very interesting concept/quantity when thought about in physics. In Newtownian physics we are used to time marching forward in a precisely clockwork way. This works fine for me when riding my bike at very moderate speeds carrying my somewhat moderate weight. My fit bit clock tells me accurately how far I have travelled during the admittedly short time that I have been cycling. However at very high speeds such as approaching the speed of light, 300,000 km/s, strange things start to happen. My fit bit clock would start running slow. I would feel immensely heavy and my height would be severely contracted.
Einstein is the person who worked out the general relativity physics to describe all of this. He came up with the concept of space-time, which takes the normal 3 dimensions with which we are familiar and fuses them with the dimension of time to produce a continuum, space-time. The smoothness of Space-time is affected by heavy objects in it such as stars leading to curves in it, causing light to bend when it passes nearby and other tricky things happening to time.
I know when I fall off my bike, I hit the earth. We think of this as my smallish mass being greatly affected by the large mass of the earth. We call this the force of gravity. Einstein, though, saw that all bodies exist in space-time with large objects causing very large curves in space-time. So the curves are really an expression of gravity.
Ripples can occur in space-time when exciting things such as supernovae happen leading to these ripples or gravitational waves. These were predicted. by Einstein in 1916 but only reported as observed very recently in 2016 for the first time using the massive LIGO detector in the USA.
So back to the gold.
As a star evolves it fuels itself by converting the simplest element, hydrogen to helium via nuclear fusion. This fusing of the hydrogen to the slightly more complex helium, gives out energy, the light which we see from the stars. Over a long period of time, billions of years, eventually the hydrogen runs out and with an increase in temperature and pressure the helium ignites and through the nuclear fusion process the even more complex element carbon is formed. The process continues with carbon fusing to form still heavier elements. This continues until the point that iron is being produced and suddenly there is a catastrophic problem, the fusing of iron will not give out energy, instead it will absorb energy and with that the star will suddenly collapse under its own weight, i.e. A situation of extreme gravity. In a fraction of a second the star collapses with the outer material falling in at huge speeds (around 20% of the speed of light). It hits the iron core of the star and a massive shock wave travels out. Over the course of a couple of hours the wave creates very extreme conditions in the star leading to the production of gold (and silver, platinum, uranium and all the other exotic heavy elements). These are then flung with massive speeds across the interstellar medium.
If this was being observed from earth, we would not see the explosion for several hours after it happened because any light being produced is obscured. However a gravitational wave is produced and we now think that we could detect this on earth at the moment of the supernova formation using the LIGO detector.
I know I'm rambling here about lots of things. There is both the extremely long timescales involved in the production of all elements which we find on earth (several billions of years), the very fast production of the gold during the supernova, seconds to hours, and the distortions in the spacetime continuum which the supernova produces. Then on the earth there are the more human like timescales of years from mining of the gold to the making of the jewellery. I know it is a bit headwrecking but I like to think that my interaction with the gold, which will last maybe a few decades is a part of the space-time continuum.
I don’t think this answers your question at all.......
MW: Thanks for clearing something up I had misunderstood! For some reason I had been under the impression that heavier elements beyond iron were the result of multiple supernova (first one creates up to iron, then the iron explodes and is scattered to be sucked up by another forming star. The second star eventually collapses and the iron within fuses into more exotic elements to be repeated). But your explanation makes much more sense and how the elements are created much more violent and faster than I had understood or imagined before!
Are binary stars usually the same size and so burn out at the same rate or is one bigger than the other? If one is bigger than the other how does that change the process?
I've always loved the image of the other end of the life of a star, the ignition. Is there a single point where a star ignites or is it a very gradual process? Kind of like the difference between dousing a BBQ with lighter fluid and getting the "womph" when the match comes into the vicinity compared to using fire lighting blocks that gradually smoulder.
I understand the process of the accretion of material gradually coming together under gravity until the star and surrounding planets are formed but just not the process of ignition.
SH: Astronomy is full of drama!
Binary stars are often highly non-identical in terms of their size. Think Arnold Schwarzenegger and Danny de Vito. Sometimes one star strips material from the other. This happens when the gravitational pull from the more massive star is greater than that of the smaller partner. So because they have different masses they will evolve at different rates. It can even lead to situations where one star becomes a black hole.
With helium fusion there can be quite an exciting phase known as the helium flash - which takes place over a few seconds. This happens in stars round about the mass of our own sun.
While the star has been burning hydrogen, the outward pressure of fusion has balanced against the inward pressure of gravity. However once the star runs out of hydrogen to burn gravity takes the lead and compresses the star smaller and tighter.
Temperatures increase with the contraction, eventually reaching levels where helium is able to fuse into carbon. Depending on the mass of the star, the helium burning might be gradual or might begin with an explosive flash. The energy produced by the helium fusion causes the star to expand outward to many times its original size.
During the helium flash there is runaway reaction with the helium fusing very rapidly to form carbon giving out about 100 billion times the star's normal energy production (for a few seconds) until the temperature increases to the point that thermal pressure again becomes dominant, exceeding the gravitational pressure. The core can then expand and cool down and a stable burning of helium will continue. This is known as the red giant phase.
MZ: Sheila, You trace a story through a small item of jewellery that takes us into a story of astronomy very immediately. I had never thought about the material of jewellery as placing us within the space time continuum, although it must have been in my thinking somewhere you will see from the images taken from the first rehearsal phase of WAAMOS. The thing that fascinates me about your responses to both Matthew and I is you are also leading me to think of astronomy as a choreographic drama where the stakes are very high, where bodies are colliding, crashing, collapsing, causing massive shocks and disturbances.
So, you both did and didn't answer my question which I guess makes it both the right and wrong question!
The research for we are all made of stars over the past six months has demanded that we enter into many kinds of dialogues. Outside of studio time many of these conversations have happened remotely and all of them have revealed different knowledges situated across film, music, choreography, astrophysics and theatre. The process has produced more questions than we could possibly follow in one project.
We are looking forward to talking again with Dr Gilheany but until then we want to thank her for giving permission to share some of our correspondence