[ExI] Neutrino interaction web

Anders Sandberg anders at aleph.se
Fri Mar 4 10:50:41 UTC 2011

Adrian Tymes wrote:
> Simple exclusion.  Neutrinos can slip through the spaces inside ordinary
> matter, because they don't interact electromagnetically.  But they can't
> actually occupy the same space as a neutron, can they?

Sorry, particle physics doesn't behave much according to common sense.

Remember that neutrinos and quarks are as far as we know point 
particles, and the neutron is about 2*10^-16 m across. Most of it is 
empty space. Worse, if two particles have no interactions allowed my 
understanding of quantum field theory says that they will just pass 
through each other. A bit like how light gets through glass since there 
is no electrons with the right energy gap for it to react with.

Ben Zaiboc wrote:
> Creating a molecule with just 3 carbon atoms would be .. difficult .. 
You are just pessmistic. It exists: cyclopropane.

At least chemistry makes sense. But it is after all almost on our own 
size scale.

Anders Sandberg,
Future of Humanity Institute 
James Martin 21st Century School 
Philosophy Faculty 
Oxford University 

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