Colloquia, seminars and talks by

Stephen W. Morris


I have various talks, which I evolve, mix and match.  The following are some examples.

 


Go to the Nonlinear Physics Group home page



The Experimental Nonlinear Physics Group, Dept. of Physics, University of Toronto

60 St. George St. Toronto, Ontario, Canada, M5S 1A7. Phone (416) 978 - 6810

 


Art, Outreach and Pattern Formation


For the past several years, I have been experimenting with the boundary between art and science. I have repurposed my scientific images of pattern formation experiments and pattern-forming natural phenomena by presenting them as art. I have exhibiting images and videos in art galleries and juried art shows. I have brought artists into my research lab for several hands-on workshops. I am the co-organizer of the "ArtSci Salon", an evening meet-up group at the Fields Institute of Mathematical Science in Toronto. I have released a trove of icicle shape data for free use under the Creative Commons. I have collaborated with sound artists and composers to use pattern formation images and videos as input to their creative processes. All these activities can be viewed equally as art-making or as scientific outreach.


The scientific field of pattern formation has developed a distinct aesthetic sensibility, informed by mathematics and physics, but inherently visual and dynamic. This aesthetic is an essential motivation for this work.


This talk describes my experiences in this "application" of pattern formation to making, exhibiting and discussing art. My experience shows that unmodified scientific images can be well received as art and generate wide-ranging conversations across traditionally separate disciplines. The art world offers an interesting venue for science outreach activities, as well as being a lot of fun to explore.


Here is a video of this talk at the Isaac Newton Institute

Links:  The ArtSci SalonThe Icicle AtlasFlickr stream



Consider the Icicle


Icicles are harmless and picturesque winter phenomena, familiar to anyone who lives in a cold climate.  The shape of an icicle emerges from a subtle feedback between ice formation, which is controlled by the release of latent heat, and the flow of water over the evolving shape.  The water flow, in turn, determines how the heat flows.  The air around the icicle is also flowing, and all forms of heat transfer are active in the air.  Ideal icicles are predicted to have a universal "platonic" shape, independent of growing conditions.  In addition, many natural icicles exhibit a ripply shape, which is the result of a morphological instability.  The wavelength of the ripples is also remarkably independent of the growing conditions.  Similar shape and ripple phenomena are also observed on stalactites, although certain details of their formation differ.  We built a laboratory icicle growing machine to explore icicle physics. We learned what it takes to make a platonic icicle and the surprising origin of the ripples.


Work done with Antony Szu-Han Chen.  Relevant publications on this work.

Here is an online version of this talk, given at Georgia Tech, Feb.4 2013.

See also The Icicle Atlas, an open source data project.


A Supernova in a Jar


This talk will describe chemical experiments in which an autocatalytic reaction is used to generate rising plumes in a fluid under gravity.  The reaction front is very thin, something like a flame front, and the reaction produces buoyancy both by releasing heat and by compositional change.  The result is a self-stirred solution in which a small “flame bubble” evolves into a plume with a complex morphology.  I will present both experiments and numerical simulations of the evolution of these plumes and “flame” balls.  They have some resemblance to the initial stages of the deflagration of type Ia supernovae.


Work done with Michael C. Rogers, Abdelfattah Zebib, Anne De Wit, Mick Mantle and Andrew Sederman,

Relevant publications on this work.


A talk for the Canadian Institute for Theoretical Astrophysics. Talk available online here.



Cracking the Giant's Causeway,

or how to solve a 300 year old geology problem using kitchen materials


Columnar joints are three-dimensional fracture networks that form in cooling lava flows. The network breaks the solid lava into an array of nearly hexagonal columns with an uncanny degree of order. Famous examples include the Giant's Causeway in Northern Ireland, Fingal's cave in Scotland and The Devil's Postpile in California. The same pattern can be observed on a smaller scale in drying corn starch, and in some other materials. We have made the first three dimensional study of the evolution of the network in corn starch and relate these observations to the mature patterns observed in field studies of lava flows. Starch columns are 1000 times smaller than their lava counterparts. We have solved a 300 year old geology problem by figuring out what sets the scale of the columns in both cases.


Work done with graduate student Lucas Goehring and L. Mahadevan.

Relevant publications on this work.


A very old Newton Institute version of this talk is here.

Another old version is a Physics colloquium at Berkeley, is online here.


Icicles, washboard road and meandering syrup

This talk will describe three recent experiments on emergent patterns in three diverse physical systems. The overall shape and subsequent rippling instability of icicles is an interesting free-boundary growth problem. It has been linked theoretically to similar phenomena in stalactites. We attempted (with limited success) to grow icicles and determine the motion of their ripples. Washboard road is the result of the instability of a flat granular surface under the action of rolling wheels. The rippling of the road, which is a major annoyance to drivers, sets in above a threshold speed and leads to waves which travel down the road. We studied these waves, which have their own interesting dynamics, both in the laboratory and using 2D molecular dynamics simulation. A viscous fluid, like syrup, falling onto a moving belt creates a novel device called a “fluid mechanical sewing machine.” The belt breaks the rotational symmetry of the rope-coiling instability, leading to a rich zoo of states as a function of the belt speed and nozzle height.


Work done with Stuart Dalziel, Nicolas Taberlet, Jim McElwaine, Jon Dawes, John Lister, Sunny Chiu-Webster and various other people at DAMTP, Cambridge University, and Neil Ribe of FAST, Paris.


Relevant publications on this work: [icicles][washboard road] [meandering syrup].

See also S. Chiu-Webster and J. Lister, J. Fluid Mech., vol. 569, p. 89-111 (2006).




That warm feeling: the evolution of electronic design from tubes to nanotechnology


No technology in the history of humanity has undergone such sweeping transformations as electronics. As part of the celebration of the Clairtone stereo exhibit, this talk will examine the physics and design of audio electronics from the 1930’s to the present day.


A DXphysics talk at the Design Exchange, part of the exhibition “The Art of Clairtone: The making of a design icon”.

Online versions of this talk: [Quicktime HiRes: 310MB] [Quicktime LoRes: 48MB] [Flash: 116MB].




Smectic film convection: A tempest in a soap bubble


Smectic liquid crystals are slimy organic liquids that form submicron thick suspended films, rather like soap bubbles.  These films are nearly perfect two-dimensional liquids, with uniform thickness down to the molecular scale.  I will describe fluid mechanical convection experiments carried out in smectic films which are forced electrically. With gentle forcing and an applied shear, we can produce a pattern of vortices that exhibits interesting nonlinear dynamics.  With strong forcing, we can study the scaling behaviour of turbulent convection.


Work done by graduate student Peichun Tsai, former student Zahir Daya and postdoc Vatche Deyirmenjian.

Relevant publications on this work.


An old Newton Institute version of this talk is here.





Sand Waves: Oscillations and Subdiffusion in Granular Segregation



Unlike fluids, dry granular materials often stubbornly refuse to mix when shaken or stirred. Instead, they sort themselves by size or shape. These "segregation" effects are common in many industrial processes involving grains from cake mixes to gunpowder, but are only rather poorly understood.  In this talk, I will describe experiments on granular mixtures that segregate when tumbled in a partially filled, horizontal rotating drum. I will attempt a live demonstration of this counterintuitive phenomenon. The dynamical evolution of segregation can, under certain conditions, be oscillatory. Continuum models of this process posit two coupled fields which oscillate out of phase with one another. We examined several candidate fields and find that all are in phase, in contradiction to a recent order parameter model. We also studied the axial transport in the tube using narrow pulses as initial conditions. Surprizingly, we find that the process is subdiffusive, rather than diffusive as assumed in the models. 



Work done by former graduate students Zeina Khan, Kiam Choo and Mike Baker.

Relevant publications on this work.


An old Newton Institute version of this talk is here.





A physicist in the sandbox



The behaviour of dry granular matter, like sand, is a continuing source of fascination.  How does a heap of sand support itself?  The answer is surprising and subtle.  Shaken grains self-organize into spectacular lattice patterns and granular gases cool into galaxy-like clusters.  Why? Unlike fluids, dry granular materials often stubbornly refuse to mix when shaken or stirred. Instead, they sort themselves by size or shape. These "segregation" effects are common in many industrial processes involving grains from cake mixes to gunpowder, but are only rather poorly understood.  In this talk, I will show many examples of the behaviour of grains, discuss some of the new ideas about them and attempt some live demonstrations of these counterintuitive phenomena.



This is a general “colloquium style” talk featuring the work of many people.

Here is a short version of this talk, given to the Tree House Group in Toronto.





Why is the Universe not Boring?  Pattern Formation in Nature


The universe is not a rigid clockwork, but neither is it formless and random. Instead, it is filled with highly organized, evolved structures that have somehow emerged from the simple rules of physics. Many natural systems spontaneously self-organize into surprisingly ordered structures, even though they are driven far from thermodynamic equilibrium. Regular spatial patterns emerge, for example, as ripples on wind blown sand, convection cells in heated fluids and columnar fracture patterns in basalt flows. These phenomena exist in spite of the universal tendency towards disorder. How is this possible? In this talk, I will explore the physics of lab-scale nonlinear patterns, and attempt a live demonstration.


This is a general “colloquium style” talk featuring the work of many people.

Here is an online version of this talk, given at Georgia Tech, Feb. 4 2013.





Dirty water, chemical plumes and cracking mud


In this talk, I will present an overview of some geophysically flavoured experiments that have been going on in the Toronto Nonlinear Physics lab in the last few years.  Under "dirty  water", we studied the front morphology of a turbidity current as it intruded into clean water. The front was unstable to a "lobe and cleft" pattern, which we were able to compare to recent theory and simulations.  In the "chemical plume" experiment, we are studying rising plumes of buoyant solution in which the density change derives from a chemical reaction.  The reaction occurs at a sharp, propagating front that converts the ambient solution into a lighter product without much temperature change. These plumes may have some analogy to chemically differentiated mantle plumes.   Finally, under "cracking mud", we have been studying shrinkage fracture patterns in drying cornstarch slurries.  These cracks mature into a roughly hexagonal columnar pattern that is closely analogous to the columnar joints observed in basalts.


This is a review talk covering several topics, including work by Jerome Neufeld, Michael Rogers and Lucas Goehring.





Images of sound relating physics and design


This presentation, given jointly by the physicist, Dr. Stephen Morris, and the artist designer, Dr. Lydia Sharman, connects their respective research into patterns created on vibrating plates, and by audio frequencies in a fluid medium, particularly the experiments of Ernst Chladni and Hans Jenny.


In the 1970's, Hans Jenny, a Swiss doctor, researcher and artist, undertook a series of experiments, in which simple audio frequencies are used to excite a liquid medium and so revealed the visual characteristics of vibrational effects and wave phenomena. The images have geometric structures and progressions similar to the mandalas, patterns and tessellations found in the art of many cultures. Dr. Sharman will show a video of patterns created by audio frequencies in a liquid medium, their relationship to the geometry of traditional Morocco zillij patterns, and the influence of these connections in her own art practice.


Hans Jenny's experiments both postdated and predated a large body of work in physics. The idea of visualizing vibration in this way goes back to Robert Hooke, who wrote about the same effect in 1680. In 1786, Ernst Chladni invented a method of visualizing the vibration of plates by sprinkling powder on them that lead to several advances in both mathematics and acoustics. Experiments on the vibration of plates with powder or fluid covering them, were taken up by Michael Faraday in the 1830's. These phenomena have only recently become the subject of scientific scrutiny. All these effects are reproduced in Jenny's experiments, including some that have been rediscovered by physicists in recent years. Dr. Morris will discuss the history and recent developments in the physics of such patterns.


This talk was presented at Subtle Technologies 2005, and was a collaboration with artist and designer Lydia Sharman.


Subtle Technologies 2005: Symposium

Here is an article based on this talk from Idea&s, the Faculty of Arts and Science magazine