[Redbook5:212-214][19880719:0000c]{Hawking
[(1)][continued
(3)]}[19th
July 1988]
(19880719. )
[continued]
[…]
*’What we think of as “empty” space cannot be completely empty
because that would mean that all the fields, such as the
gravitational and electromagnetic fields, would have to be exactly
zero. However, the value of a field and its rate of change with time
are like the position and velocity of a particle: the uncertainty
principle implies that the more accurately one knows one of these
quantities, the less accurately one can know the other. So in empty
space the field cannot be fixed at exactly zero, because then it
would have both a precise value (zero) and a precise rate of change
(also zero). There must be a certain minimum amount of uncertainty,
or quantum fluctuations, in the value of the field. One can think of
these fluctuations as pairs of particles of light or gravity that
appear together at some time, move apart, and then come together
again and annihilate each other. These particles are virtual
particles…: unlike real particles, they cannot be observed directly
with a particle detector. However, their indirect effects, such as
small changes in the energy of electron orbits in atoms, can be
measured and agree with the theoretical predictions to a remarkable
degree of accuracy.' (He then goes on to show how pairs of matter
particles may appear, and while one may fall into the black hole, the
other may escape and appear as if emitted from the black hole.)**
This
seems to be a classic example of the Scientists' tendency to take
limits on observation as limits on possibility, going on from there
in this case to build a whole explanation*** of theoretically
predicted and/or empirically observed phenomena on this basis.
Hawking is honest enough casually to discuss the possibility of a
supernatural observer,**** without apparently appreciating its
significance; the actual existence of the supernatural observer is
not required (Berkeley notwithstanding):# only the possibility of his
existence – even the possibility of considering
the possibility of his existence, is sufficient. Once you have
considered the possibility of observation not affecting the outcome,
the potential independence of the outcome irrespective of your
observation or inability to observe it is established, and the
explanation given for the particles in empty space falls.
*[Stephen
Hawking, 'A Brief history of Time', Bantam, 1988]
p105[-106]
[Chapter
7: Black Holes ain’t so black]
**[–
as
follows: 'Because
energy cannot be created out of nothing, one of the partners in a
particle/antiparticle pair will have positive energy, and the other
partner negative energy. The one with negative energy is condemned to
be a short-lived virtual particle because real particles always have
positive energy in normal situations. It must therefore seek out its
partner and annihilate with it. However, a real particle close to a
massive body has less energy than if it were far away, because it
would take energy to lift it far away against the gravitational
attraction of the body. Normally, the energy of
the
particle is still positive, but the gravitational field inside a
black hole is so strong that even a real particle can have negative
energy there. It is therefore possible, if a black hole is present,
for the virtual particle with negative energy to fall into the black
hole and become a real particle or antiparticle. In this case it no
longer has to annihilate with its partner. Its forsaken partner may
fall into the black hole as well. Or, having positive energy, it
might also escape from the vicinity of the black hole as a real
particle or antiparticle' (Ibid, [p106] [Chapter 7: Black Holes ain’t
so black])]
***(or
was the theory the explanation?)
****[See
last previous entry]
#[Presumably
a reference to the theory of Immaterialism propounded by Bishop
George Berkeley (1685-1753), and/or the summary attributed to Ronald
Knox (1888-1957):
'There
was a young man who said "God
Must
find it exceedingly odd
To
see that this tree
Still
continues to be
When
there's no-one about in the quad".
Dear
Sir, Your astonishment's odd;
I
am always about in the quad;
And
that's why the tree
Still
continues to be
Since
observed by, Yours faithfully, God.'
]
[continues]
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