Do Virtual Particles Defy the Law of Conservation of Energy?

[hadeka]

Dear all.

My question, is about "Virtual Particles".

I've read, that they appear out of nothing, and disappear in a very short time.

How could this happen ?!

How can something come from nothing ?!
Or how can something go to nothing ?!

What is nothing then ?!

Does this violates the law of energy conservation ?!

How could energy be created or destroyed here ?!

Maybe i didnt understand the whole issue that well !
So, I am asking because i really can't understand it !

Does this issue, prove the existence of a creator ?!
How come ?!
Im not religious ... I am a naturalist .. But I am really confused about this

Please try to make the answer as much as simple


Thank you ..

Waiting for replies ..


With most respect ..



Hadeka

 

[mgb_phys]

I've read, that they appear out of nothing, and disappear in a very short time.

That's correct.

How can something come from nothing ?!
Or how can something go to nothing ?!

Thats the way the universe works.

What is nothing then ?!

A little more complicated than you were taught in school

Does this violates the law of energy conservation ?!

No
<eric idle voice>you started with nothing, you ended up with nothing, what have you lost - nothing!

How could energy be created or destroyed here ?!

It isn't the energy is just sort of borrowed for a while, it's like an overdraft.

Maybe i didnt understand the whole issue that well !
So, I am asking because i really can't understand it !

On the quantum level things aren't cut and dried as 'real world' it's just a bit fuzzy.
Things are only 'probably' in a certain position, only have an approximate speed and change when you look at them - virtual particles are about the most sensible thing!

Does this issue, prove the existence of a creator ?!
How come ?!
Im not religious ... I am a naturalist .. But I am really confused about this

Quite the opposite, as Einstein said 'God doesn't play dice'.
It could prove a slightly incompetent creater!

 

[hadeka]

Thank you for your answer ..

But excuse me ,, maybe i need more simple explanation !

What i understand from the law of energy conversation, is that energy is eternal .. it has no beginning, nor an end ... because it can't be created nor destroyed ..

so can energy come out of nothing ?!

In my opinion, if it came from nothing ,, so "nothing" exists .. and if "nothing" exists,, so it is no longer nothing !

How can nothing produce something ?!
"ZERO" + "Zero" ,, can never produce something ... we need something to produce something else ...

This idea seems like religious ideas, that god created the world out of nothing !
How could this happen ??!

And please (if possible), try to explain a little bit ,, how can this disprove the existence of a creator ?!

Thank you ..

With most respect ..

 

[strangerep]

Virtual particles are a fictitious artifact of the mathematical techniques
used to calculate stuff perturbatively in quantum field theory. They have no
physical reality, as can be seen by the fact that different perturbation
schemes involve different "virtual particles" (although all the schemes
produce the same answer for physically-observable results in the end).

Here's a trivial illustration: 2 oranges + 2 oranges = 4 oranges, right?

But 2 oranges + 5 dragons - 3 dragons + 2 oranges - 2 dragons is
also 4 oranges. Does this mean that dragons have physical reality?
No, of course not.

The math in quantum field theory is far more difficult than the above,
but the basic point is that virtual particles arise from how one is
trying to compute a result. I.e., they're "on paper" only.

 

[colorSpace]

But 2 oranges + 5 dragons - 3 dragons + 2 oranges - 2 dragons is
also 4 oranges. Does this mean that dragons have physical reality?
No, of course not.

The math in quantum field theory is far more difficult than the above,
but the basic point is that virtual particles arise from how one is
trying to compute a result. I.e., they're "on paper" only.

Nice example. But it makes me think... if they are really needed, even if just for computation, isn't that a sign that the other parts of the computation don't correspond to "reality" either, since they seem to be missing something?

 

[morbidwork]

A photon has four options when traveling through space it either keeps on moving, hits an electron and has all of its energy absorbed (photoelectric effect), part of its energy absorbed (Compton effect), or form pair production where the energy of the photon is converted into mass. These masses are an electron and a positron. The two opposite charged masses then come together and annihilate. The energy required to form these two masses is 0.51 MeV each and any excess energy results in the two particles having a velocity according to K = 1/2 mv^2. Once the annihilation has occurred 2 gamma rays are formed which directions must be able to follow conservation of both energy and momentum. Therefore the two photons could now be traveling in different directions which can be observed. As well Hawking believes that if this event occurs around a black hole one of the particles may fall into the event horizon while the other one escapes making it appear that the black hole is in fact emitting particles.

 

[hadeka]

thank u all ..

Well .. i mean here by "nothing", the philosophical "Absolute nothing" ..

But i found out that this is doesn't exist ,, it is just a philosophical concept

And the "Nothing", that physics is talking about, is the Zero-Point Energy in the vacuum ...
So it has been created from that energy ..

So, did i get it ?!
Is this right ?!

There is nothing called nothing (Philosophical absolute nothing)

waiting for replies and confirmations !

 

[strangerep]

... if [virtual particles] are really needed, even if just for
computation, isn't that a sign that the other parts of the computation don't
correspond to "reality" either, since they seem to be missing something?

I'm not sure what you're alluding to. Large amounts of the QFT machinery of
renormalization are devoted to extracting finite results from a mathematically
ill-defined theory. The Higgs field was invented to get a renormalizable
theory of massive vector bosons. It will be really interesting during the
next few years to see whether the Higgs is found experimentally -- or not.
Either result will suggest something important about whether renormalizability
should be regarded as a guiding theoretical principle (like gauge invariance),
or just as a mathematical artifice (like ghost fields).

 

[strangerep]

[...] the "Nothing", that physics is talking about, is the
Zero-Point Energy in the vacuum ...

More precisely, the vacuum is a state of lowest energy.

So it has been created from that energy ..

No, you can't "create" things from "that energy" - because that would
require the vacuum to have less energy afterwards, which is
impossible because the vacuum is already the state of
lowest energy.

So, did i get it ?! Is this right ?!
There is nothing called nothing (Philosophical absolute nothing)

Well, you can't interact (non-trivially) with nothing, so this is like the
time-wasting philosophical question of whether a tree falling in the
forest makes a sound even when there's no one to hear it.

 

[colorSpace]

I'm not sure what you're alluding to. Large amounts of the QFT machinery of
renormalization are devoted to extracting finite results from a mathematically
ill-defined theory. The Higgs field was invented to get a renormalizable
theory of massive vector bosons. It will be really interesting during the
next few years to see whether the Higgs is found experimentally -- or not.
Either result will suggest something important about whether renormalizability
should be regarded as a guiding theoretical principle (like gauge invariance),
or just as a mathematical artifice (like ghost fields).

Well, the question is abstractly, whether the other components of the computation are out of balance without the virtual particles, or whether the virtual particles balance each other out, so that the remaining components are in balance and could be consider a complete representation of reality, even without the virtual particles.

Your example suggests the latter, but I was wondering whether perhaps the remaining components need the virtual particles to give a balanced picture. So that without the virtual particles, the picture would be too incomplete to be a representation of reality.

But perhaps the whole mathematical picture is too "ill-defined" anyway to be considered a representation of reality. If you know what I mean.

 

[RandallB]

excuse me ,, maybe i need more simple explanation !

What i understand from the law of energy conversation, is that energy is eternal .. it has no beginning, nor an end ... because it can't be created nor destroyed ..
so can energy come out of nothing ?!

And please (if possible), try to explain a little bit ,, how can this disprove the existence of a creator ?!

For a very simple one, image a test enclosed inside a beach ball; where you are able to measure the total energy contained.
An object moves against friction resistance on board form one spot to another. Mathematically you might explain that with energy from “magic Virtual Particles” but with a rule.
When you go to re-measure the total energy inside your beach ball (including the HEAT that must have been created by that friction the total) energy has not changed. Using “energy” from a virtual particles comes with rules that such energy must immediately be lost back to them. And immediate means the extra energy is never measureable as having ever existed in the total system inside your beach ball.

Science did not find chess pieces moving by themselves, but it can build useful mathematical models using virtual particles that do not create or change total energy to work with otherwise difficult to understand yet now more predictable events observed at small scales.

Do not assume or draw greater conclusions than just that much; or you are jumping to a philosophical conclusion (such as is or is not a creator “real” or "disproved") which has nothing to do with the success of using Virtual Particle tools to predict particle behavior.

 

[Tom Delacour]

...My question, is about "Virtual Particles".
I've read, that they appear out of nothing, and disappear in a very short time.
How could this happen ?!...Thank you ..With most respect ..Hadeka

Heisenberg's Uncertainty Principle. ( HUP )

Virtual particles are a fictitious artifact of the mathematical techniques... I.e., they're "on paper" only.

Not true, virtual particles are a consequence of HUP and explain the well-documented Cassimir Effect which is otherwise difficult to explain and also are part of Hawking Radiation.

Heisenberg's Uncertainty Principle dictates that there are certain pairs of properties of a quantum entity e.g. the position ( one property ) and velocity ( the other property in the pair ) of an electron.
These pairs of properties are such that neither property exists, that is, neither property is defined, even in principle, until a measurement is made ( a measurement means the quantum entity somehow interfaces or interacts with the environment, such as an electron arriving at a detector ).
The greater the accuracy of one property being defined ( measured ), the less accuracy is defined to the paired property.
In our example, if you measure roughly the electrons position, you can also roughly measure ( or calculate ) it's velocity ( speed and direction ), but if you measure very accurately its position, then it is not possible, even in principle, to measure or calculate its velocity.
This means that if you know where it is now, you have no idea where it will be the next moment you look. It's not a shortcoming of our measuring devices or of the mathematics. The mathematics shows that the velocity isn't even defined!

Now, another pair of values are the energy of a quantum system and the time duration of it having that energy.
Again, as described by HUP, the more accurately one of these pairs is defined, the less accurately defined is the other paired property.
A piece of space smaller than the Planck length may be considered as a quantum entity.
Essentially, a true vacuum is empty. Of everything. Thus if there is truly nothing there, not even energy, then the energy is precisely ( infinite accuracy ) defined as exactly zero.
But the duration of that space having zero energy is simply not defined because of the energy/duration pair of properties thus energy 'must' appear (in the form of virtual particle pairs ). The energy is borrowed from the rest of the Universe and then repaid within the Planck time by the particles anihilating each other. It's as if the law of energy conservation is violated, but only in local spacetime, the average energy within the entire Universe is still conserved.
These particles are usually too short lived to interact with the environment hence are not 'real' remember 'reality' from human perspective is what we can somehow measure but because they disappear before they can be measured, virtual particles are not real in the normal sense but they exist unobservably, hence their name, Virtual particles.

Hawking ( know the Mind of God ) Radiation is supposedly when one of the virtual particles is sucked into black hole and the other escapes so they can not anihilate each other back to energy to repay. The escaped particle becomes real and keeps it's enerygy.
Personally, I don't buy it but I'll have to write my reasons elsewhere on that.

Another thing:

...Quite the opposite, as Einstein said 'God doesn't play dice'...

Why quote a great scientist for one of the most stupid things ever said aloud?
Please quote the genius on the stunning science he did and not his inane religious babblings--are all you popular science book authors taking notes??
If Hawking can know the Mind Of God ( his own words ), perhaps he could confirm that ? Genius got to their heads in more ways than one!

 

[strangerep]

Virtual particles are a fictitious artifact of the mathematical techniques...
... I.e., they're "on paper" only.

Not true, virtual particles are a consequence of HUP and explain the well-documented
Cassimir Effect which is otherwise difficult to explain and also are part of
Hawking Radiation.

(Sigh.) It always seems to offend some portion of the population when virtual
particles are explained as having no physical reality.

The Casimir effect (only one 's', btw) arises because one is imposing spatial
restrictions upon the EM vacuum. The (unrestricted) vacuum has zero energy
and momentum - and therefore its position is completely indeterminate (by
the HUP). When one imposes spatial restrictions, as occurs with the Casimir
effect, the HUP implies that this must induce a corresponding indeterminacy
in energy-momentum. This can be analyzed more quantitatively by figuring
out how many modes are possible in the spatially-restricted region, and
the Casimir force can be calculated by figuring out whether there's more
or fewer modes when a slight change is made to the restriction boundaries.
So... there is no question that the HUP is a physically verifiable principle.

But that was not the point. That virtual particles in Feynman diagrams are
somehow physically real,-- that cannot be so -- for the reasons I mentioned
in earlier posts.

Regarding the Hawking-Unruh effect, those (theoretical) effects arise
because we are taking a Poincare-invariant theory (QFT) and placing
it into a larger context (curved spacetime with general diffeomorphisms
in the Hawking effect, and accelerated observers in Rindler space for
the Unruh effect). Both the effects arise because different observers
cannot agree in general on what the "vacuum" is. One observer's
empty vacuum is another observer's seething thermal ocean. In such
situations, the whole notion of "particle" becomes dubious (regardless
of whether they're "virtual" or "real").

 

[reilly]

Heisenberg's Uncertainty Principle. ( HUP )These particles are usually too short lived to interact with the environment hence are not 'real' remember 'reality' from human perspective is what we can somehow measure but because they disappear before they can be measured, virtual particles are not real in the normal sense but they exist unobservably, hence their name, Virtual particles.

Why quote a great scientist for one of the most stupid things ever said aloud?
Please quote the genius on the stunning science he did and not his inane religious babblings--onfirm that ? Genius got to their heads in more ways than one!

If these virtual particles cannot be observed, how do you know they exist? strangerep has got it right. As in, do Coulomb scattering in a perturbative scheme, vs. exactly in parabolic coordinates. Why don't the virtual particles of approach 1 show up in approach 2 -- or do they?

Indeed there are resonances, some of which are extremely short lived, but are known by means of their decay products. And.they are virtually never fully described by a few orders of perturbation theory -- cf. Wigner-Weiskopf and Breit-Wigner approaches.

You are not in the same league as Einstein; calling him or something he's done stupid. is demeaning to him, and especially to you.

Regards,
Reilly Atkinson

 

[Tom Delacour]

...
You are not in the same league as Einstein; calling him or something he's done stupid. is demeaning to him, and especially to you.
...

I didn't call him or anything he did stupid-- please read above I called him a genius. However, his talking of God in scientific context is entirely silly. Remember, he said that as he could not accept the 'random' nature of quantum physics. To appeal to any religion or theology when discussing science is not only silly, it is dangerous. I also found Hawking's writing of knowing the Mind of God as equally silly. All people are silly sometimes--yes, even me!-- to imply someone is beyond criticism for certain specific points because of otherwise great works or deeds isn't logical.

 

[DaveC426913]

However, his talking of God in scientific context is entirely silly. Remember, he said that as he could not accept the 'random' nature of quantum physics. To appeal to any religion or theology when discussing science is not only silly, it is dangerous. I also found Hawking's writing of knowing the Mind of God as equally silly.

I think you're overreacting.

There's nothing wrong with viewing science as a subset of the understanding of God. This is a human belief. (Any scientist who believes in God does this implicitly)

The problem is when someone attempts to view God as a subset of science. That's invalid.

Einstein and Hawking are apparently believers. That does not mean they're unscientific.

I think you're exhibiting a knee-jerk reaction to the usual case of someone trying to analyze God with science. But that's not what they're doing.

 

[Tom Delacour]

Thank you for your thoughtful comments, Dave.
What you say is true. Oops.

 

[lightarrow]

Coming back to virtual particles, even on this forum (don't remember the name of the thread) recently it was said that, actually, all particles, in a sense, are virtual. Someone knows the meaning of this?

Edit. The thread was this:
https://www.physicsforums.com/showthread.php?t=195429&highlight=virtual

 

[reilly]

That you wish to criticize Einstein's ideas or statements; no problem. It's how you choose to do it. Damning with faint praise is almost always a vastly more powerful way to criticize than is the use of red-flag words like, stupid and silly. Words like that turn people away, and neutralize your argument. And, hey, if you object to the imposition of religion into science, why read the offending work?

I'm a hard-core empiricist and reductionist, and Darwinist. But. religion and science? Who am I to say? There are people of great eloquence on both sides of the issue.
Regards,
Reilly Atkinson

I didn't call him or anything he did stupid-- please read above I called him a genius. However, his talking of God in scientific context is entirely silly. Remember, he said that as he could not accept the 'random' nature of quantum physics. To appeal to any religion or theology when discussing science is not only silly, it is dangerous. I also found Hawking's writing of knowing the Mind of God as equally silly. All people are silly sometimes--yes, even me!-- to imply someone is beyond criticism for certain specific points because of otherwise great works or deeds isn't logical.

 

[DaveC426913]

I'm a hard-core empiricist and reductionist, and Darwinist. But. religion and science? Who am I to say? There are people of great eloquence on both sides of the issue.

You know, he has a point that I think may give pause for thought to a great many of us here.

Seems to me "we skeptical atheistic types" (forgive the generalized labelling, maybe we can refine that) as a group stand by a couple of principles:

1] We consider ourselves rational, scientific and logically-minded people
2] We all pretty much agree (nay, insist) that God and religious matters are outside the purview of science.

It seems to be that this leads to the virtually inescapable conclusion that each of us must recuse ourselves from a discussion on the matter.

It sort of forces us to - rather than say "(insert your favourite derisive comment here such as 'religious faith is ridiculous') - to say "this is a matter of which I cannot speak".

How can any of us atheists who live by the scientific method justify having any opinion at all?

 

[strangerep]

Coming back to virtual particles, even on this forum (don't remember the name of the thread) recently it was said that, actually, all particles, in a sense, are virtual. Someone knows the meaning of this?

Edit. The thread was this:
https://www.physicsforums.com/showthread.php?t=195429&highlight=virtual

IMHO, it was just a bit of confusion or misunderstanding between the participants in
that thread.

The standard meaning of "real" and "virtual" in this context is that "real" particles are
"on-shell", (ie they satisfy the SR equation relating invariant rest mass to energy-momentum),
whereas virtual particles are "off-shell" - meaning that they don't satisfy that equation.
Somewhere in Zee's QFT book he talks about this under a heading "the cost of not
being real".

 

[gullapalli]

Hello, may be I am a little helpful to you...?
The first point you put in your doubt is 'nothing'.
But you shouldn't be surprised that there is no Vaccum (nothing), according to Quantum Mechanics. There is always a field. This universe is all made up of different quantum fields; the trees, the earth, yourself, myself and even the Vaccum !
So when you come to know that there is no 'nothing' in your question,half of your boubt is cleared.
The second part is that, whether the creation of the virtual particles violates the law of conservation of energy. I expect that you know about Einstein and his 'mass energy equivalance' [ E = mc^2 ].
So from the above equation we understand that there are no separate conservation laws for mass and energy, but there is only a single conservation law and that law states that the total amount of mass and energy must be a constant.
I think that this had made your mind easy, isn't it ?

 

[gullapalli]

Hello, may be I am a little helpful to you.
The first point you put in your doubt is 'nothing'.
But you shouldn't be surprised that there is no Vaccum (nothing), according to Quantum Mechanics. There is always a field. This universe is all made up of different quantum fields; the trees, the earth, yourself and myself !
So when you come to know that there is no 'nothing' in your question,half of your boubt is cleared.
The second part is that, whether the creation of the virtual particles violates the law of conservation of energy. I expect that you know about Einstein and his 'mass energy equivalance' [ E = mc^2 ].
So from the above equation we understand that there are no separate conservation laws for mass and energy, but there is only a single conservation law and that law states that the total amount of mass and energy must be a constant.
I think that this had made your mind easy, isn't it ?