>> This act of something creating itself out of nothing is a necessary
>> consequence of Heisenberg's uncertainty principal, as (simplistically),
if
>> the space was empty and stayed that way we would know that there was
>> "nothing" there and that the nothing had zero velocity.
>> As we are not allowed to know exactly both exactly where something is and
>> exactly what its velocity is (even if the "something" is a piece of
>> 'nothing") then
>> the vacuum MUST arbitrarily generate bits of matter/energy so we can't
>know
>> what is exactly happening.
>
>WTF??


I take it that that acronym is "an earthy Anglo Saxon expletive/
interrogative" :-)
Maybe not.

If so, are you asking what I am talking about or something else ???

I'll assume the former and go for an attempt at a "short simple statement"
of how I understand things.
Read this until your head hurts and then apologise for asking :-).
Anyone who has a good grasp of Cosmology & particle Physics 101 may wish to
correct my more glaring generalisations. Warning: Any corrections are liable
to make things weirder.

James wants course notes and working (fair enough too !) and as I seem to
have left these at home today I'll give some links instead at the end :-).

Heisenberg in his HUP (Heisenberg uncertainty Principle) established that it
was impossible to simultaneously measure both an object's position and
velocity with absolute certainty. As one measurement is made with increasing
accuracy the other result automatically becomes worse.

This is a basic tenet of quantum theory.

This can be thought of in terms of the measuring system necessarily
perturbing the item measured but this is a simplistic model and not actually
correct (even though this is how it's explained in ref 1 below) . The real
assertion is 'that's just how things are folks". You cant have velocity AND
position to 100% accuracy both at once.

For real world size objects the errors are so small as to be utterly
irrelevant.

For sub-atomic particles the limits imposed on measurements are significant.

If we observe a complete "vacuum", at a point we observe that there is
absolutely nothing there and that it is not moving at all.
We now know the exact velocity and the exact position of something (even
though it is nothing). This violates the HUP
While this may sound stupid to us, nature takes the violation very
seriously.
Nature WILL allow such violations for very short periods. (Based on
momentum, mass and Plank's constant - search for these and vacuum
fluctuations to know more (or less).

Nature's clever solution is qf - "quantum foam" - a random spontaneous
generation of particles and their antipartticles in the vacuum in such a
manner that at any stage the HUP is not violated for more than an acceptable
period. If these particles stay in existence too long they start affecting
things as if they are "real" particles (which they indeed are) so nature
arranges to have them annihilated shortly after their creation.

Spontaneous qf particles do not have to annihilate with their original
partners as long as they are back in jail before the Plank time quantum
traffic cop gets upset.

Apparently Nature (which didn't;'t exist until it had done this) contrived
to burp the universe up as a super version of such a fluctuation as an
Instanton although this does rather seem to do violence to the quantum
traffic cop who is probably desperately trying to put it back in its
non-existent bottle ever since. Whether it succeeds depends on whether the
result is "open or closed" and this nobody yet knows.

The nature of the initial burp is also rather unknown and ref 3 below gives
two theories which are incompatible with each other and to a large extent
with themselves (this is referred to in the vernacular as "bold" ). I like
the Hawking version as it has naked singularities and when you have them the
universe can be a really fun place !!!.

You don't of course have to believe any or all or most of this (or the parts
that I have got wrong) but if you don't you are liable to find yourself
taking a position of faith against received truth.

I believe some parts of it but I don't know which ones.
.

regards


        Russell McMahon

refs follow:

____________________________________________________________________

From 1st ref below. Note that he explains "why" this is so, even though it
isn't why :-)


In the Quantum Mechanical world, the idea that we can measure things exactly
breaks down. Let me state this notion more precisely. Suppose a particle has
momentum p and a position x. In a Quantum Mechanical world, I would not be
able to measure p and x precisely. There is an uncertainty associated with
each measurement, e.g., there is some dp and dx, which I can never get rid
of even in a perfect experiment!!!. This is due to the fact that whenever I
make a measurement, I must disturb the system. (In order for me to know
something is there, I must bump into it.) The size of the uncertainties are
not independent, they are related by

dp x dx > h / (2 x pi) = Planck's constant / ( 2 x pi )
______________________________________________________

Excellent simple overview

    http://zebu.uoregon.edu/~imamura/208/jan27/hup.html

Good bio

    http://www.aip.org/history/heisenberg/p01.htm

Vaguely relevant, fun and confusing.
Whose instanton do you choose from ?

    http://www.damtp.cam.ac.uk/user/gr/public/qg_qc.html

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