Biophysics in a chicken’s eye

This article (and news story) is great for many reasons. Mostly, it shows why the melding of physics and biology is so fruitful. Without physics, it is hard to explain why we should get so excited (a “new phase of matter”!) but without biology, we probably would not have guessed that something so weird would (or could)  evolve in the first place. In other words, physics helps us describe the world, but it is a little too unbounded… life comes and reminds us where the limits really are, and sometimes, they are beyond what we thought was possible. It is also pretty neat that there are still many mysteries to explore, even in familiar farm animals.

Phases of matter depend on the interactions between particles. Gasses are basically collections or atoms or molecules that bounce off each other randomly. Interparticle attraction is required for solids to form a crystal lattice.

Physicists find a new 'state of matter' in the eyes of chickens

Magnets can also be thought of as having phases. The interaction between dipoles allows for the possibility of long range ordering. In the chicken eye, cones of the same type “repel” each other, solving an evolutionary problem of efficient packing. The end result is somewhere between a solid and a liquid:

Physicists find a new 'state of matter' in the eyes of chickens

“At one level, it’s like a crystal that greatly suppresses differences in the density of particles across large spatial distances. But at another scale, it’s liquid-like in that it exhibits similar physical properties in all directions.”

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Book Review: Sleights of Mind

I just finished reading Sleights of Mind, a fascinating book by two neuroscientists about what magic can teach us about how the mind works. The main premise is that the human brain can be fooled by magical illusions because of the shortcuts it takes in order to work efficiently under everyday situations. Conjurers have intuited how to hack these heuristics, and science can learn a great deal from them.

Among the most exploitable brain mechanisms is what the authors call the “spotlight of attention.” Consciousness is far from a faithful representation of reality. In order to make sense of the world, the brain is constantly enhancing nerve signals from objects you are focusing on, and suppressing nearby impulses. This automatic filter is why misdirection is so effective. As a big Penn and Teller fan, my interest was piqued by the participation of Teller in the book. Here he is performing the famous Cups and Balls trick, with transparent cups. Even knowing that you are being fooled does not prevent the illusion.


Although silent during their acts and television show, Teller is happy to share his insights about the deeper meaning of magic.

Among the other famous magicians is Apollo Robbins, “the world’s greatest pickpocket.”

From Nature Reviews Neuroscience:

“Just as vision scientists study visual art and illusions to elucidate the workings of the visual system, so too can cognitive scientists study cognitive illusions to elucidate the underpinnings of cognition. Magic shows are a manifestation of accomplished magic performers’ deep intuition for and understanding of human attention and awareness. By studying magicians and their techniques, neuroscientists can learn powerful methods to manipulate attention and awareness in the laboratory. Such methods could be exploited to directly study the behavioural and neural basis of consciousness itself, for instance through the use of brain imaging and other neural recording techniques.”