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Q: virtual particles - are they part of the missing mass ( Answered 5 out of 5 stars,   2 Comments )
Question  
Subject: virtual particles - are they part of the missing mass
Category: Science > Physics
Asked by: doug22-ga
List Price: $10.00
Posted: 29 Mar 2003 14:12 PST
Expires: 28 Apr 2003 15:12 PDT
Question ID: 182950
I've read that particles are popping into existence and then being
annailated again everywhere in space. I have 3 quesions about this.
1. How fast does this happen, i.e., what is the cycle time of the
popping in and out?
2. Is it happening in my body right now or just in the vacuum of
space?
3. Do they exert a gravitation effect on the rest of the universe? My
thinking if these "quantum foam" particles are everywhere and if they
exert a gravitational effect could this be part of the dark matter
they are looking for?
Answer  
Subject: Re: virtual particles - are they part of the missing mass
Answered By: lmnop-ga on 29 Mar 2003 16:27 PST
Rated:5 out of 5 stars
 
Hi, your question is really great and made me deal with ideas I’ve
wondered about myself. So it was a pleasure to make some headway
below. The one thing to keep in mind is that theories and even data in
this field are always open to change and revision, though the decades
have solidified some aspects pretty well. There is a little wiggle
room in some of the terminology, and even in the accuracy of some
statements taken at face value. But I think I’ve narrowed down to the
truth as understood for now!

At “The Particle Adventure” site they make the statement that
production and annihilation of particle pairs happens so quickly they
can’t be observed. This implies that the particles do exist but are
extremely fleeting. I think studying the Heisenberg Uncertainty
Principal will yield different times for different kinds of particles
and masses, but that's a big issue in itself.

http://particleadventure.org/particleadventure/frameless/virtual.html

Other sites emphasize the existential aspect that the virtual
particles simply can’t be observed due to their nature (if they were
observed, they wouldn’t exist, or something to that effect). Or that
they are a theoretical constuct based on a statistical probabiliy of
their existence. One example is here at a Stanford Linear Accelerator
site:

http://www2.slac.stanford.edu/vvc/theory/virtual.html

A site that approaches the issues but in a rather deeper way (over my
head frankly) is the Matt McIrvin discussion here:

http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html

The answer to the second part of your question is that yes, pair
production and annihilation is happening everywhere, and a simple
example from a Fermilab scientist is here:

http://www.fnal.gov/pub/inquiring/questions/virtual_particles.html

Finally, the answer to the third part of your question is that the law
of energy conservation (which accounts for mass and energy over time)
is upheld by the theories currently used to describe virtual particle
actions. That means that even though some of the virtual particles
exist, they are the result of the decay of other particles, or are
created from energy such as gamma rays (which is a form of mass,
loosely speaking). Nearly all of the sites make some reference to this
conservation issue. They do suggest that the particles can briefly
have MORE mass than their parents, but this is explained away by the
extremely brief duration of the particle’s existence.

The most readable explanation I found came from a U of Oregon physics
lecture notes on line, which says quite clearly that even a pure
vacuum, pairs of particles can appear and disappear spontaneously.
This is taught by Jim Imamura and can be found here:

http://zebu.uoregon.edu/~imamura/209/apr14/virtual.html

You might then conclude that huge numbers of particles are coming and
going in the deep vacuum of space, as you speculated. But that doesn’t
seem to be true.

A clarifying explanation at this Cornell site makes the point that
particle pair production occurs in a vacuum when higher energies are
applied (and the implication is that this isn’t a pure vacuum any
more). They go on to very clearly say that most of empty space really
is empty. Here it is:

http://www.lns.cornell.edu/spr/2002-10/msg0044603.html

Another article approaching your last idea directly is this question
and answer forum at a Cornell site, which deals in a more complex way
with the gravity of the tiny pairs during their brief existence, but
it sounds like it is still a hypothetical discussion.

http://www.lns.cornell.edu/spr/2002-01/msg0038426.html

You don’t really seem to ask for detailed math (luckily for me) and so
I hope these answers will suit you. This cutting edge of physics will
always have room for doubts, and I think the third part to your
question is potentially unresolved, but it seems that the conventional
conservation of energy limitations keep you from explaining away the
mysterious hidden mass of the universe.

But you never know, sometimes the most brilliant ideas just take some
persistance (and that dreaded math) to make someone believe. That
surely goes beyond us here today. I hope that doesn’t disqualify this
answer!

Please ask for clarification on anything before rating this answer.
I'm not sure how much more definite I can be, but I want to make sure
you are satisfied! Thanks.

Search Strategy:
virtual particle
particle pair production
particle pair production mass gravity

LMNOP-ga
doug22-ga rated this answer:5 out of 5 stars
He opened up the subject for me to furthur explore and got that I
didn't want the math.  A great first experience.  Can I request that
person for a crack at my next question?

Comments  
Subject: Re: virtual particles - are they part of the missing mass
From: neilzero-ga on 30 Mar 2003 05:32 PST
 
I suspect some of this is techno-babble which will eventually
disappear from mainstream science. In the meantime it is helping get
grant money. (1) Your ideas are in line with the popular media
understanding. (2) it is happening inside your body, perhaps more than
in space.  (3) Virtual particles probably account for less than 1% of
the mass of the universe at any instant. Zero percent if this is
nonsense.   Neil
Subject: Re: virtual particles - are they part of the missing mass
From: hummer-ga on 23 Apr 2003 07:01 PDT
 
Hi doug22,

"Can I request that person for a crack at my next question?"

Yes you can, no problem - simply put "FOR LMNOP-ga ONLY" in the
subject field of your next question.

hummer

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