Natural Order and Science

[robvalue]

Can you please take this discussion of actual science to a more appropriate thread!

(Just kidding!)

[Alex K]

Basic definition: two electrons interact, they exchange a photon. That photon is "virtual". It's not going to be a photon that any of my detectors  - eyes, voltmeters, or whatever apparatus I have at hand - will register. The photon goes from one electron to the other. Period. It's virtual.

Now, should a photon be emitted by an electron and not absorbed - for whatever reason, then that photon can be detected (by my eyes or any other detector). That photon is observable, so it's not a virtual photon. The reason you can see is that there are gazillions of those photons floating around, bouncing everywhere and then.

Now if you understand that basic definition, then we can talk about interactions, what are they, how are they calculated, what role does the Heisenberg Principle play, what are Feynman diagrams, what's their use, what's their limitations, what's renormalization, what's gauge theory, what role does symmetry play in QFT, what's the advantages of going through the Hamiltonian as opposed to the Lagrangian formulation, what about the Feynman path integral, what's the core idea behind QFT, and why do we need QFT instead of QM, and a dozen other topics. But if you have trouble of understanding basic definition, we're not going to get anywhere.

Look, thanks for the table of contents of a field theory textbook you just gave, I think I know the basic definition well enough, but I also think that these categories are not very useful once you get to the dirty details
( but I'm still unhappy by one point in your explanation. You say that virtual photons are those that are exchanged between electrons. And real photons are emitted but not absorbed. But then if they are supposed to be registered by a detector, they need to be absorbed by an electron or proton in the detector, and that, at the end of the day, is an exchange, right?)

But - I think you misunderstood me, my point was not that there cannot be any technical distinction between virtual particles and others (though I don't find these categories the way you use them too useful). I was merely pointing to the technical distinction and arguing that it is philosophically dubious to say based on that, that one kind "really exist" whereas the other is just an artefact of the calculation. My point always was that such an ontological distinction is not as obviously justified as was stated upthread.

[I_am_not_mafia]

Quote mining and deliberately mangled up to make it look like his own argument. I've reported him.

For example, in the electric field when two electrons approach each other, their charges create a disturbance in the electromagnetic field. This disturbance pushes them apart and their paths bent outwards. That also work if an electron and a positron approach each other however, the disturbance in this case similar in type but different in details with the result that the oppositely charged electron and positron are attracted to each other. Their paths are bent inwards.

http://profmattstrassler.com/articles-an...-are-they/

The word "particle" is a poor conceptual description that only makes any sense in the jargon of perturbative quantum field theory (pQFT). I think that people who are not trained in pQFT should consider the word "virtual" to correspond to the excitation's particle-ness. It is not really a particle in any meaningful sense of the word. But it does correspond to something that exists for some short time.

https://m.reddit.com/r/askscience/commen...ly_proven/

In fact, what we call a particle is a nice regular ripple in a field one that can travel smoothly and effortlessly through space. This so called Virtual Particle is a disturbance in a field that would never be found on its own. It does not have energy to become a well formed ripple moving through space. This kind of disturbance will decay or break apart once its cause is gone.

http://profmattstrassler.com/articles-an...-are-they/
https://www.quora.com/Why-should-ones-co...-particles

In the Quantum Field Theory view, actual particles are viewed as being detectable excitations of underlying Quantum Fields.
Virtual Particles are also viewed as excitations of the underlying fields, but appear only as forces, not as detectable particles. They are "temporary" in the sense that they appear in calculations, but are not detected as single particles. Thus, in mathematical terms, they never appear as indices to the scattering matrix, which is to say, they never appear as the observable inputs and outputs of the physical process being modelled.

https://en.wikipedia.org/wiki/Virtual_particle

The Standard Model:
Standard Model is made of all stable Fermions. If we add the excited state versions of these Fermions, we get the full view. All space is filled with matter fields. They can spawn Fermion particles as waves. This includes all Leptons and Quarks. These particles carry one or more charges. Colour Charge, Electromagnetic Charge, and Weak Hyper Charge. Particles with a charge filled space around them with a force field. They can spawn force particles when excited by particles that carry that charge.

http://howfarawayisit.com/wp-content/upl...-Boson.pdf

According to the First Law of Thermodynamics, nothing in the Universe (i.e., matter or energy) can pop into existence from nothing. All of the scientific evidence points to that conclusion.

Energy could not have popped into existence without violating the First Law of Thermodynamics. So in reality, when scientists argue that quantum mechanics creates something from nothing, they do not really mean “nothing.” The problem of how everything got here is still present. The matter generated in quantum theory is from a vacuum that is not void.

http://www.apologeticspress.org/apconten...ticle=4584

But what if quantum theory could allow for spontaneous generation at the quantum level? What if the First Law of Thermodynamics does not apply at the unobservable molecular world of quantum mechanics but only to the macroscopic world that we can actually see? Even if that were the case (and there is no conclusive evidence to support the contention that there are any exceptions whatsoever to the First Law of Thermodynamics, according to the Big Bang model) the quantum level cosmic egg eventually became macroscopic through expansion or inflation. Such an event would have been the equivalent of a breach of the First Law, even under such a speculative definition.

But is not it true that one usually assumes that the current laws of physics did not apply at the beginning? Assumptions must be reasonable. What evidence could be used to back such a grandiose assumption? And again, who would have written the laws at the moment they became viable? And further, if the laws of physics broke down at the beginning, one cannot use quantum law to bring about matter, which is precisely what the quantum fluctuation theory attempts to do.

Conclusion
Can quantum mechanics create Universes from nothing? No!

Quantum particle generation requires pre-existing energy—a far cry from nothing.

Tiny quantum particles fluctuating—bouncing around—is one thing. The creation of the entire Universe through a quantum fluctuation? That’s another.

One who wishes to avoid acknowledging the existence of God should be expected to do almost anything to deny it. Reason will be thrown aside, and acceptance of far-fetched theories—theories that are so speculative that they belong in the fiction section of the library along with the The Wizard of Oz—will be latched onto as fact.

http://www.apologeticspress.org/apconten...ticle=4584

[little_monkey]

Look, thanks for the table of contents of a field theory textbook you just gave, I think I know the basic definition well enough, but I also think that these categories are not very useful once you get to the dirty details
( but I'm still unhappy by one point in your explanation. You say that virtual photons are those that are exchanged between electrons. And real photons are emitted but not absorbed. But then if they are supposed to be registered by a detector, they need to be absorbed by an electron or proton in the detector, and that, at the end of the day, is an exchange, right?)

Yes, of course the photons are absorbed by the electrons in your eyes, but if you understand the definition, those electrons in your eyes are part of the detector. So by definition, those electrons are not VIRTUAL. You think you understand the basic definition, but you don't. BTW, that table of contents, I can teach you every single topic in that table of content. I'm not bragging, I'm just stating a fact.

But - I think you misunderstood me, my point was not that there cannot be any technical distinction between virtual particles and others (though I don't find these categories the way you use them too useful). I was merely pointing to the technical distinction and arguing that it is philosophically dubious to say based on that, that one kind "really exist" whereas the other is just an artefact of the calculation. My point always was that such an ontological distinction is not as obviously justified as was stated upthread.

 Before discussing any topic or the validity of any theory, it would help if you can understand basic definitions, otherwise we will pass each other and never get anywhere. Secondly, I've never made the claim that one photon is "more real" than the other. Go back to my earlier post where I stated, "For the record: virtual particles are particles you can't see. Not that they are not real or some kind of illusion." 

Just to elaborate on this topic. From classical physics, we would look at these interactions in the following way: two electrons are closed to each other, and we would see that they get off their initial position. We would conclude that there was a force between them, in this case an electric repulsive force. In QFT, the language changes to: two electrons interact by exchanging virtual photons, and so they go off their initial position. We don't get to "see" the virtual photons, how could we,  but by making that assumption, QFT gives results that agree with lab confirmation to the tune of one part in 10-8. So far, there isn't any other theory that can best that result. 

But you could argue, how do I know this is taking place - this exchange of virtual particles? It's no more different than Einstein postulating that molecules are in motion, and then explaining Brownian motion on the basis of that hypothesis. Do we really see those molecules in motion? Not really. And so this is science in action: you make an hypothesis that gives a theory in the mathematical form of an equation, you make calculations, then you check your (theoretical) results against what's observed in the lab. If you get confirmation, then it's a green light for your hypothesis/theory/equations. No confirmation means go back back to square one, and start all over.

[Alex K]

Yes, of course the photons are absorbed by the electrons in your eyes, but if you understand the definition, those electrons in your eyes are part of the detector. So by definition, those electrons are not VIRTUAL. You think you understand the basic definition, but you don't.

Oh, so your definition of virtual particles is / contains that they don't interact with the detector? Can you point me to a textbook source or so where this definition is introduced?

BTW, that table of contents, I can teach you every single topic in that table of content. I'm not bragging, I'm just stating a fact.

I will gladly learn something new about quantum field theory from you, but your pompous tone is a bit off-putting. For example, you suddenly elaborated on an entire (and irrelevant) course outline on the topic when the discussion was about what we consider virtual particles. To what end, intimidate me? If you can do what you claim you can do, you have no need for this kind of posturing. Show, don't tell.

[Alex K]

Quote mining and deliberately mangled up to make it look like his own argument. I've reported him.

I suspected as much.

[Fidel_Castronaut]

I have dealt with him. Reprehensible.

Harris, as an academic and a moderator I say apox on you for making me do all that work checking those fucking sources to see just how despicable your quote mining was.

Kudos to Mathilda for making my job easier.

[Neo-Scholastic]

Merely taking the world as intelligible is a leap of faith. Believing that we can know anything is a leap of faith. There are no 'purely' rational positions.

There are leaps of faith which occur in the absence of rational support and those that occur with the presence of rational support.  Just because there are no purely rational positions does not mean that we can't rank positions according to their reasonableness.  Some leaps of faith are larger than others.  The leap to belief in an entity unlike any that has been observed to occur in our everyday world is surely one of the largest.

I do not disagree. I was thinking of the fundamental approaches people can take when confronted with their own existence and also have a sense of something(s) other than themselves. Your example reveals the unavoidable circularity of first principles. One must first take a "leap of faith" affirming the efficacy of reason before one can say whether that leap is reasonable. Most participants of AF do accept the efficacy of reason, but I have noticed a sharp division between those who take the stance that reality is actually intelligible versus those who consider it apparently so.

[Alex K]

Chad, an honest question - while I acknowledge that the efficacy of reason is not obviously a given and more like a working assumption which appears to yield consistent results, I still wonder, is there a coherent notion of the alternative? Could reality be unintelligible or might such a sentence be meaningless.

[little_monkey]

Yes, of course the photons are absorbed by the electrons in your eyes, but if you understand the definition, those electrons in your eyes are part of the detector. So by definition, those electrons are not VIRTUAL. You think you understand the basic definition, but you don't.

Oh, so your definition of virtual particles is / contains that they don't interact with the detector? Can you point me to a textbook source or so where this definition is introduced?

  You keep repeating the same mistake. I'm not saying that they don't interact, I'm saying those photons who do interact with you, the detector,  via the electrons in your eyes are not called VIRTUAL. These are the observable ones. So last time,

(1) Particles interacting between themselves through the exchange of photons: those photons are VIRTUAL. One particle emitted the photon, the other particle absorbed it. That photon never passed through your eyes, or any other detector. They are not observable, you cannot see them, they are called VIRTUAL.

(2) Photons interacting with any part of a detector: your eyes, your voltmeter, your Geiger counter, whatever, these are observable, hence they are NOT virtual. 

I will gladly learn something new about quantum field theory from you, but your pompous tone is a bit off-putting. For example, you suddenly elaborated on an entire (and irrelevant) course outline on the topic when the discussion was about what we consider virtual particles. To what end, intimidate me? If you can do what you claim you can do, you have no need for this kind of posturing. Show, don't tell.

I have no need to intimidate you. My first posting in this thread was addressed to all who were posting in this thread. That's why I started that post with: "For the record..." If you took that as a personal attack, that is your interpretation, I had no such intention. If I failed to convince you on the strength of my arguments, then that's my fault. But I sense from this post from you that you seem to be not in any mood to dialogue. So I will terminate this conversation.