{Hawking [(1)][continued (3)]}[19th July 1988]

[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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