[FOM] John Baez on David Corfield's book
Stephen G Simpson
simpson at math.psu.edu
Sat Oct 4 19:32:57 EDT 2003
Alexander M Lemberg Sat, 4 Oct 2003 16:07:01 -0600 writes:
> exotic R^4, a differentiable manifold which is homeomorphic but not
> diffeomorphic to the usual R^4. This phenomenon is unique to 4
> dimensions.
OK, good. Corfield and others asserted many times that there is lots
of philosophically interesting mathematics other than f.o.m. I kept
asking for examples, but none was forthcoming. I am glad to finally
have an example on the table.
However, I don't find this example completely convincing.
What do you see as the philosophical interest of exotic R^4? Have
philosophers used exotic R^4 in a serious way to address serious
philosophical issues? Perhaps you are going to say something about
our 4-dimensional world being possibly homeomorphic or diffeomorphic
to R^4 or exotic R^4. I don't see that this is a philosophical
question, but maybe you do, and I am willing to be persuaded.
---
Stephen G. Simpson
Professor of Mathematics
Penn State University
http://www.math.psu.edu/simpson/
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