Fifty Years of Sphere Eversions
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Transcript of Fifty Years of Sphere Eversions
50 years of sphere eversions
Tony Phillips
Stony Brook, 2016
Second edition, augmented
Stephen Smale - 1959
TAMS 90 281-290
Stephen Smale - 1959
TAMS 90 281-290
Arnold Shapiro - 1960
Shapiro’s eversion was only generally known much later. Hedied in 1962, but had told his construction to Bernard Morin.Morin published it with George Francis in 1980. “Arnold Shapiro’s eversion of the sphere.” Math Intell 2 200-203
drawing by George Francis
Nicolaas Kuiper -1961
Kuiper in 1961 – Photo by Paul Halmos
CMH 35 85-92
May, 1966
Marcel Froissart, Bernard Morin 1967
One of the clay models Morin used to communicate his mental pictures.
Marcel Froissart, Bernard Morin 1967
http://www.lutecium.fr/mirror/www.jp-petit.com/science/maths_f/Retournement_sphere/PLS_79.pdf.
These pictures were published much later (1979) by Morin and Jean-Pierre Petit.
“Turning a Sphere Inside-Out” - 1976
Nelson Max
“Turning a Sphere Inside-Out” - 1976
Nelson Max
Stephen Smale
“Turning a Sphere Inside-Out” - 1976
Nelson Max
Charles Pugh
“Turning a Sphere Inside-Out” - 1976
Nelson Max
Nelson Max
Interactive: John Hughes -1984
George Francis: A Topological Picturebook - 1987
Francis observed that Morin’seversion is one of a family of“tobacco pouch” eversions.The central stage can have 2, 3, 4, 5, …-fold symmetry.
3: Boy’s Surface 4: Morin’s Surface
from George Francis’ illustrations of Morin’s eversion.
Thurston’s “Outside-In” - 1994
The Optiverse - 1996
Iain Aitchison - 2010
http://arxiv.org/abs/1008.0916The `Holiverse': holistic eversion of the 2-sphere in R3
Arnaud Chéritat- 2014
http://arxiv.org/abs/1410.4417“Yet another sphere eversion”
What happens to the rest of the surface?
Greenhemisphere
Greenhemisphere
Yellowhemisphere
Yellowhemisphere
Greenhemisphere
Greenhemisphereattached here
Greenhemisphereattached here
Greenhemisphereattached here
Greenhemisphereattached here
Greenhemisphereattached here
Greenhemisphere
Yellowhemisphere
Yellowhemisphere
Greenhemisphere
Greenhemisphere
What happens to the hemispheres during the eversion?
We trace the attaching surface ofone of the hemispheres.
Upper green hemisphereattached here.
One of the fourhemisphere-attachingsurfaces, tracedthrough the eversion.