[itisus (OP)]

The BB begat real particles, and some of those begat other real particles, etc.  Real particle are accompanied by swarms of virtual particles.  Occasionally virtual particles mate with real particles to beget different real particles.  Yet virtual particles never beget real particles on their own.  At least not in polite company.  What is the mysterious force that passes on the quality of being "real"?  Yeah, I know the uncertainty routine, but what passes on the "real" property?

[Ethos]

Someone else here at Naked may have a proper answer for you, nevertheless, I will offer my own opinion about this peculiar property of matter. As we all understand, virtual particles are constantly coming in and out of existence everywhere around us. So why don't they stick around long enough to get aquainted with their new surroundings? BTW, this question is a very good one and I have also pondered it at length. I can only rationalize one explanation: Virtual particles are only comfortable when occupying extradimensional space. By this I mean, our 4 dimensional space is not sufficient or compatable with virtual particles. I believe if this could be proved, it would also prove the existence for parallel universes. In another universe parallel to our own, the atoms that make up our existence may be viewed by it's occupants as only virtual particles also. 

[lightarrow]

The BB begat real particles, and some of those begat other real particles, etc.  Real particle are accompanied by swarms of virtual particles.  Occasionally virtual particles mate with real particles to beget different real particles.  Yet virtual particles never beget real particles on their own.  At least not in polite company.  What is the mysterious force that passes on the quality of being "real"?  Yeah, I know the uncertainty routine, but what passes on the "real" property?

For real particles the following relation holds:

E² = (cp)² + (mc²)²

E = particle's total energy
p = particle's momentum
m = particle's mass

For virtual particles that relation doesn't hold. Energy is still conserved, momentum is still conserved, but they are not linked by that relation, which is also known as "mass shell" relation; so virtual particles are "out of shell". For example, they can have imaginary mass, virtual photons can have a non-zero mass, ecc.

[Vern]

I might add to lightarrow's very accurate post that virtual particles can be virtual only so long as they are not detectable. If they can be detected then they are real. Some say that when they are detected they become real.

Virtual particles replaced the field concept. The idea of field is that a varying amplitude of force may extend outward from a source and impart action to something anywhere within the field. But physicists didn't like that idea because it implied a spooky action-at-a-distance concept. So, we invented virtual particles that may pop into existence and act within an area to impart action to something within that area.

So we replaced a spooky action-at-a-distance concept with a spooky particle concept. [] The particle is more spooky than the field to me.

In both cases the amount of action that may be imparted is the gauge of the field, so we call the concepts, gauge theories. I like to think of the field the old way. I don't mind action at a distance; but if it helps ease the mind, they're okay; gauge theories work either way.   

[yor_on]

It's a lovely question.
What defines a particle, sort of.

Virtual particles is only known by their interactions.
http://en.wikipedia.org/wiki/Vacuum_fluctuation#Manifestations
http://www2.slac.stanford.edu/vvc/theory/virtual.html

So 'something' exists, and we call it 'virtual particles'.
It seems to be a 'property' of what we call vacuum.

--
Here is a interesting article about "zero point energy" (ZPE), even if a little old.
http://users.erols.com/iri/ZPEpaper.html Reading this paper you will see some talk about "Grigg's Hydrosonic Pump"
I tried to goggle on it but found no proof for it being used as of the last years. I'm interested though, so if someone knows how that 'worked out'?

----
As well as this recent one.
http://byzipp.com/energy/
And for those of you curious (like me:) if this is just another scam.
http://venturebeat.com/2008/05/30/blacklight-power-claims-nearly-free-energy-from-water-is-this-for-real/

But ZPE is a extremly strange subject:)

Here is another paper on it.
http://www.calphysics.org/articles/merc2000b.html

--------------------------

We will see when the LHC starts up:)
http://www.symmetrymagazine.org/breaking/2009/02/13/high-energy-physics-beyond-emc2/

"Scientists hope to find particles like the Higgs boson, which physicists theorize gives mass to matter. They also hope to find supersymmetrical particles, partner particles that mirror known particles but have much greater mass. But should the particles that physicists seek prove too massive for even the LHC to pry from the vacuum, physicists have another crack at them at the intensity frontier."

And at this 'intensity frontier' they have hope of catching the interactions of 'virtual particles' with kaons and muons.

[Vern]

The ZPE concept is very interesting but it seems that it is being allowed to die a natural death. Zero Point Energy is a take off of the vacuum fluctuations that are observable. I suspect, and this is just my own speculation, that vacuum fluctuations are the result of random electromagnetic energy that moves through all of space.

[itisus (OP)]

The ZPE concept is very interesting but it seems that it is being allowed to die a natural death. Zero Point Energy is a take off of the vacuum fluctuations that are observable. I suspect, and this is just my own speculation, that vacuum fluctuations are the result of random electromagnetic energy that moves through all of space.

ZPE is only speculative if you define it as something one can extract work from.  I am rather Put off by that idea, but the Casimir Force is real enough and does bounce very small things around.  What is the difference between observing a little lever bounce and observing the thing (wave, particle) that bounces it?  Do we observe real electrons or their effects on instruments?

I have been curious about "mass-shell," and this is the first time I have seen a definition.  P^2+ M^2 = E^2 for real particles, so what is the relation for virtual particles?

[lightarrow]

I have been curious about "mass-shell," and this is the first time I have seen a definition.  P^2+ M^2 = E^2 for real particles, so what is the relation for virtual particles?

P^2+ M^2 ≠ E^2

[yor_on]

Vern.
Did you look at http://www.calphysics.org/articles/merc2000b.html ?
They also discuss electromagnetism.

[itisus (OP)]

I have been curious about "mass-shell," and this is the first time I have seen a definition.  P^2+ M^2 = E^2 for real particles, so what is the relation for virtual particles?

P^2+ M^2 ≠ E^2

Well, that is about as explanatory as the Wikipedia entry.

[Vern]

Vern.
Did you look at http://www.calphysics.org/articles/merc2000b.html ?
They also discuss electromagnetism.

Very interesting paper yor_on; I especially liked the section that attempted to link gravity and the Zero Point Energy field.

[lightarrow]

I have been curious about "mass-shell," and this is the first time I have seen a definition.  P^2+ M^2 = E^2 for real particles, so what is the relation for virtual particles?

P^2+ M^2 ≠ E^2

Well, that is about as explanatory as the Wikipedia entry.

You mean that it's not explicatory? If I say that the characteristic of all the body "A" is their spherical shape, while all the body "B" don't have, which means that they can be of any other shape, what else do you need to know?

[Raghavendra]

When light falls on the object, the object is real...Otherwise no,.

[lightarrow]

When light falls on the object, the object is real...Otherwise no,.

So light cannot be real...  []

[techmatt]

When light falls on the object, the object is real...Otherwise no,.

Does that mean a black hole is not real?