-2

I've recently delved back into some alternative interpretations of quantum field theory.

While Richard Feynman often emphasized that calculations were sufficient and discouraged fixation on the "true" nature of events, his Nobel Lecture suggested exploring diverse avenues for advancing theoretical physics. It's pertinent to note that Feynman Diagrams, known for their utility in calculations and visualization, are isomorphic to the rigorous Schwinger-Tomonaga formulation, as established by Dyson.

My familiarity with QFT extends to the Lehmann–Symanzik–Zimmerman (LSZ) reduction formula derived from Lagrangian formalism, as well as the equivalent results obtained via the path integral formalism.

The proposed reinterpretation below predominantly abandons the particle-centric view and instead focuses solely on fields which must be in line with the rigorous Schwinger-Tomonaga formulation, with which I am not familiar.

I'm particularly curious whether Schwinger-Tomonaga- Dyson's rigorous formulation serves merely as another way of calculating amplitudes or if it indeed imparts insights into the physical processes underlying particle scattering—specifically, the moments before, during, and after.

The proposed reinterpretation posits that, during particle scattering, the energy-momentum of incoming fields interacts with quantum fields existing in the vacuum.

Unlike the traditional view involving virtual particle exchange seen in Feynman Diagrams, this interpretation posits that the interaction primarily occurs between the energy of incoming fields and vacuum quantum fields in a localized spacetime region.

This energy transfer excites the lowest energy fields in the vacuum into becoming real observed outgoing particles.

Does this reinterpretation, which deviates from the conventional portrayal through Feynman diagrams, offer a better comprehension of the physical process?

Could it prompt a reevaluation of long standing assumptions? Despite being rooted in the same QFT framework, does this reinterpretation indicate a promising path to fresh insights into the fundamental physical processes?

In summary, this question aims to determine the compatibility of the presented reinterpretation with established QFT interpretations which use virtual particles and the potential implications for advancing our understanding of fields interactions. The traditional concept of virtual particles is sidelined, with a focus on fields, rather than virtual and real particles as the primary entities driving interactions.

References:

Feynman, R. P. (1965). The Character of Physical Law. MIT Press.

Dyson, F. J. (1949). The radiation theories of Tomonaga, Schwinger, and Feynman. Physical Review, 75(3), 486.

Lehmann, H., Symanzik, K., & Zimmermann, W. (1955). On the formulation of quantized field theories. Il Nuovo Cimento, 1(2), 205-225.

VVM
  • 413
  • You might well be writing an ode to Schwinger’s original QFT formulation without the turgid math. Dyson liberated us from this “deeper understanding” in 1949, no? – Cosmas Zachos Aug 21 '23 at 10:50
  • 9
    A Feynman diagram is a graphical representation of a term of a perturbation expansion. Nothing more, nothing less. – my2cts Aug 21 '23 at 10:58
  • 1
    The history of said liberation. Our world has hardly ever looked back, for evident reasons… – Cosmas Zachos Aug 21 '23 at 11:08
  • Didn't know that, very helpful, thanks, but the question is not about mathematics or calculations, but about the actual sequence of physical events. – VVM Aug 21 '23 at 12:04
  • 3
    Feynman diagrams are indeed mathematical calculations though, a graphic representation of them. – freude Aug 21 '23 at 13:02
  • This really sounds like natural philosophy (the defunct ancient way of discussing nature). Feynman diagrams aren't the result of physicists going "what if particles bounced off each other by creating virtual particles". There is a very simple set of assumptions (that the universe has quantum fields) that mathematically leads to calculating physical observables. Feynman diagrams are just a step in the calculation. So there's no sense in going "what if actually the energy interacts with blah blah blah..." Just learn quantum field theory and not just the qualitative statements written about it. – AXensen Aug 21 '23 at 16:20
  • What if saying that "virtual particles are mediating energy or momentum exchange between incoming particles", an insight often shown in or obtained from a Feynman diagram, is blah blah blah... – VVM Aug 21 '23 at 18:05
  • the actual sequence of physical events There is no “actual sequence of physical events”. Just like a quantum particle does not have a trajectory, because it can’t have a well-defined position and velocity, a quantum field does not have an evolution, because its values at different points in space and the rate of change of those values cannot both be well-defined. In the Feynman path integral approach the field evolves in all possible ways simultaneously. It is impossible to apply classical ideas like an “actual sequence of events”. – Ghoster Aug 21 '23 at 18:05
  • Agreed, removed, but what about understanding the underlying physical process, assuming the same mathematical framework, yet without thinking of a virtual particle exchanging energy momentum between incoming particles and noting that incoming particles only interact with the fields of the vacuum. – VVM Aug 21 '23 at 18:20
  • Words like “particle” and “field” don’t matter. A quantum field has particle-like characteristics, so you are making a false dichotomy between fields and particles. And why would you want to think of the incoming and outgoing stuff as particles but the intermediate stuff as fields? There is only one kind of “thing” in quantum field theory: quantum fields. And only the equations matter, not the words or the mental images. – Ghoster Aug 21 '23 at 18:55
  • 1
    Feynman diagrams … might not fully capture the underlying physical processes at play. Since they are graphical representations of terms in a perturbative expansion, they can’t represent non-perturbative effects. – Ghoster Aug 21 '23 at 19:18
  • "only the equations matter", exactly, and already said it above: "this viewpoint emphasizes the nature of the theory itself—it's not just particle theory; it's a field theory. Even the concept of virtual particles becomes secondary and not required" – VVM Aug 21 '23 at 19:29
  • @VVM I think you'd enjoy Virtual Particles: What are they? by Matt Strassler, but also see https://physics.stackexchange.com/q/230113/123208 especially the answer by A Curious Mind. – PM 2Ring Aug 22 '23 at 01:31
  • Excellent, so far it seems that many agree that the exchange of virtual particles between incoming particles doesn't make sense physically although they are useful fictions for easy quick calculations – VVM Aug 22 '23 at 11:06
  • 2
    "These fields aren't mere backdrops; they teem with potential. According to this perspective, all potential outgoing particles preexist as virtual particles within the vacuum, waiting for an infusion of energy to become observable." is not a possible interpretation. First of all "they teem with potential" is too vague even for theoretical physics. Secondly, if they preexist and are just awaiting incoming high energy particle to liberate, then lepton-lepton scattering should behave like hadronic showers, and experiment shows they do not. Voting to leave closed. – naturallyInconsistent Aug 22 '23 at 18:09
  • Shut up and calculate. – RC_23 Aug 24 '23 at 02:40
  • I can take the renowned quote on shut up and calculate as an acceptable answer. – VVM Aug 24 '23 at 19:29

1 Answers1

2

all possible outgoing particles are actually pre-existing as virtual particles, matter and anti matter, within the vacuum.

Consider the Higgs particle with a mass-energy of 125 GeV. If you have a virtual Higgs just sitting there in what you refered to as a "vacuum", it's going to have this energy. Energy fluctuations in the vacuum are possible, but they are constrained by the Heisenberg uncertainty principle:

$$\Delta E \cdot \Delta t \sim h$$

where $\Delta E$ is the uncertainty in energy, $\Delta t$ is the uncertainty in time and $h$ is the planck constant. This means, if a Higgs particle would suddenly appear, the energy would shift by $\Delta E = 125$ GeV, so the time before it decays again would be at most

$$\Delta t \sim \frac{h}{\Delta E} \sim 10^{-26} \text{ s}$$

The Higgs can't exist for longer, because this would violate the uncertainty principle. The same is true for all other virtual particles (lighter ones can exist for a little longer).

So in my mind, this idea of virtual particles just "sitting" in the vacuum awaiting energy to turn into real particles doesn't work, because the mass-energy is always there.

Also note that Feynman diagrams were never meant to provide any deep insight into the nature of quantum interactions. They are just a useful tool for calculations, nothing more.

Lenard Kasselmann
  • 949
  • You said, "because the mass-energy is always there", please explain a little more, also please note that "Even the concept of virtual particles becomes secondary and not required" in this interpretation. – VVM Aug 21 '23 at 12:05
  • @VVM Well, each elementary particle has a certain mass $m$. When the particle is at rest, i.e. has no momentum, its energy is given by $E = mc^2$. This is whats's meant by mass-energy or rest energy. If you want to create a real particle of mass $m$, the amount of energy you have to provide at minimum is $E = mc^2$. So you can't have a massive particle sitting inside the vacuum without any energy. – Lenard Kasselmann Aug 21 '23 at 13:11
  • 1
    @VVM However, it's totally correct to think about particles as excitations of the underlying Quantum fields. This is precisely what the math shows. Each particle species is associated with a Quantum field which streches through all of space. If you provide some energy, you create a local "ripple" in the field, which we then call a particle. – Lenard Kasselmann Aug 21 '23 at 13:20
  • @VVM In my opinion, "particle physics" is a bad name, because it makes you think that particles are the fundamental objects we are studying, when in fact, the fundamental objects are fields. – Lenard Kasselmann Aug 21 '23 at 13:27
  • So basically, you are supporting this interpretation where I say "localized energy alone, (without any need for virtual particles), can breathe life into the vacuum fields and cause the emergence of real particles." – VVM Aug 21 '23 at 13:33