Explanation:
Why doesn't
matter just bunch up?
The same principle that keeps
neutron stars and
white dwarf stars
from imploding also
keeps people from imploding and makes
normal matter mostly empty space.
The observed reason is known as the
Pauli Exclusion Principle.
The principle states that identical
fermions -- one type of
fundamental matter -- cannot be in the same place
at the same time and with the same orientation.
The other type of matter, bosons, do not have this property, as
demonstrated clearly by recently created
Bose-Einstein condensates.
Earlier this decade, the
Pauli
Exclusion Principle was
demonstrated graphically in the
above picture of clouds of two
isotopes of lithium -- the left cloud composed of
bosons while the right cloud is composed of
fermions.
As temperature
drops, the bosons bunch together, while the
fermions better keep their distance.
The reason why the
Pauli Exclusion Principle is true and the physical limits
of the principle are still unknown.
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