How does exchange of elementary particles result in a force?

[vcsharp2003]

Homework Statement:: I came across the following in an online article. I am unable to understand how these elementary particles cause a force to exist.

"Each of the four forces results from the exchange of force-carrier particles.".

Above statement is taken from https://www.livescience.com/49254-weak-force.html
Relevant Equations:: None

In Physics, we have four fundamental types of forces, namely Gravitational, Electromagnetic, Strong Nuclear and Weak Nuclear forces. Also, we have indivisible particles like quarks and bosons within an atom. Bosons are considered force carrier particles that are mentioned as the root cause of each of the fundamental forces in Physics.

I cannot understand what a force carrier particle means. How can a particle carry force? Probably, a particle that carries energy is considered a force carrier particle in Quantum Physics. Also, I have no clue as to what it means to say "exchange of force carrier particles". For example, how does exchange of boson particles occur for a block resting on the floor so that a normal reaction force comes into existence?

 

[Drakkith]

From Theoretical Physicist Matt Strassler in this article: https://profmattstrassler.com/artic...ysics-basics/virtual-particles-what-are-they/

(Regarding the interaction of two electrons passing near to each other)
Physicists often say, and laypersons’ books repeat, that the two electrons exchange virtual photons. But those are just words, and they lead to many confusions if you start imagining this word “exchange” as meaning that the electrons are tossing photons back and forth as two children might toss a ball. It’s not hard to imagine that throwing balls back and forth might generate a repulsion, but how could it generate an attractive force? The problem here is that the intuition that arises from the word “exchange” simply has too many flaws. To really understand this you need a small amount of math, but zero math is unfortunately not enough. It is better, I think, for the layperson to understand that the electromagnetic field is disturbed in some way, ignore the term “virtual photons” which actually is more confusing than enlightening, and trust that a calculation has to be done to figure out how the disturbance produced by the two electrons leads to their being repelled from one another, while the disturbance between an electron and a positron is different enough to cause attraction.

In short, this 'exchange' is not like throwing balls back and forth to each other. It's an unfortunate consequence that the details of the math can, kind of, if you look at it squinty-eyed and tilt your head sideways, be translated to layman's terms as an 'exchange' of a 'virtual particle'.

The details are very complicated since you would need to learn the actual math used to do QED (quantum electrodynamics) calculations to understand exactly what is meant by 'exchange' and 'virtual particle', but suffice to say that they are not like the everyday definition we use.

 

[vcsharp2003]

From Theoretical Physicist Matt Strassler in this article: https://profmattstrassler.com/artic...ysics-basics/virtual-particles-what-are-they/

(Regarding the interaction of two electrons passing near to each other)
Physicists often say, and laypersons’ books repeat, that the two electrons exchange virtual photons. But those are just words, and they lead to many confusions if you start imagining this word “exchange” as meaning that the electrons are tossing photons back and forth as two children might toss a ball. It’s not hard to imagine that throwing balls back and forth might generate a repulsion, but how could it generate an attractive force? The problem here is that the intuition that arises from the word “exchange” simply has too many flaws. To really understand this you need a small amount of math, but zero math is unfortunately not enough. It is better, I think, for the layperson to understand that the electromagnetic field is disturbed in some way, ignore the term “virtual photons” which actually is more confusing than enlightening, and trust that a calculation has to be done to figure out how the disturbance produced by the two electrons leads to their being repelled from one another, while the disturbance between an electron and a positron is different enough to cause attraction.

In short, this 'exchange' is not like throwing balls back and forth to each other. It's an unfortunate consequence that the details of the math can, kind of, if you look at it squinty-eyed and tilt your head sideways, be translated to layman's terms as an 'exchange' of a 'virtual particle'.

The details are very complicated since you would need to learn the actual math used to do QED (quantum electrodynamics) calculations to understand exactly what is meant by 'exchange' and 'virtual particle', but suffice to say that they are not like the everyday definition we use.

For a layman like me, exchange of boson particles could mean the electromagnetic field in the vicinity of interacting objects gets disturbed and this disturbance manifests as a physical force that we identify at a macro level. The manifestation part it seems has a mathematical basis. So, we cannot explain manifesting of a force using our macro reasoning concepts of Physics, but need to use some special Math to explain it.
Does that sound ok from a layman's perspective?

 

[Drakkith]

So, we cannot explain manifesting of a force using our macro reasoning concepts of Physics, but need to use some special Math to explain it.
Does that sound ok from a layman's perspective?

I'd say that you can't use your everyday intuitive understanding of nature to understand how things work at the quantum level (or the cosmological level either for that matter). The mathematics involved are only 'special' because the average person doesn't learn enough math to understand them. The basic kinematic equations of motion are as 'special' to someone who can only do simple arithmetic as the QED equations are to people who know math only up to algebra.

 

[malawi_glenn]

This is a good article about virtual particle exchange https://www.physicsforums.com/insights/physics-virtual-particles/ and its follow up https://www.physicsforums.com/insights/misconceptions-virtual-particles/

 

[vcsharp2003]

I'd say that you can't use your everyday intuitive understanding of nature to understand how things work at the quantum level (or the cosmological level either for that matter). The mathematics involved are only 'special' because the average person doesn't learn enough math to understand them. The basic kinematic equations of motion are as 'special' to someone who can only do simple arithmetic as the QED equations are to people who know math only up to algebra.

But, we can say that the manifestation of a fundamental force starts with electromagnetic disturbance around the objects interacting through a physical force?

 

[malawi_glenn]

But, we can say that the manifestation of a fundamental force starts with electromagnetic disturbance around the objects interacting through a physical force?

No

 

[vcsharp2003]

No

Ok. That's what I thought after reading the first answer. So, it would be more correct to say the it all starts with exchange of boson particles?

 

[vcsharp2003]

From Theoretical Physicist Matt Strassler in this article: https://profmattstrassler.com/artic...ysics-basics/virtual-particles-what-are-they/

The above article is really awesome in explaining it to a classical Physics student. The author has done an excellent job of giving a single explanation of Quantum interactions between two real objects.
Searching my question online gives search results with different explanations for this question and it becomes very difficult for a high school student to understand what exactly is the fact. But the article you gave offers a very good explanation.

 

[malawi_glenn]

I think that article just replace the "virtual particle exchange" with a somewhat muddy concept of "disturbance". The part highlighted by Drakkith is the message you should take home.

you would need to learn the actual math used to do QED (quantum electrodynamics) calculations to understand exactly what is meant by 'exchange' and 'virtual particle

Interacting scalar QFT is enough :-) For instance interaction terms like $\lambda \phi^3$ is enough to construct a toymodel where you can compute tree-level scattering matrixelements and cross sections (sure you would encounter problems like renormalization etc beyond tree level)
No need to invoke fermion and gauge fields :-)

 

[MRMMRM]

The forces we experience is gravity and electromagnetic force, specifically of just the negative electrons repelling each other and the potential energy well created by the gigantic mass of the earth. They both work over extremely far distances. They cancel each other out based on their strength at distance.
The only force carriers you can sense are photons, the carriers of the electromagnetic force. Our eyes are narrowband detectors for them. You can also say we feel heat as photons at frequencys out side of that band, but that is like saying you feel gravity by not being weightless, its not as direct, and more of just the potential energy side of the force, not observing the force being carried/ transported like reflections and refractions.

This is where it starts to get less intuitive and more statistical/ probable.
If you get into chemistry, you get more into the electromagnetic force, with the balance of the positive and negative sides of it. The periodic table being a collection of elemental stable systems, and molecules storing stable potential energy that can also be released as kinetic energy.

Then this is where imagination, math, and a large collider is needed. Related to the article you were reading.
Inside of the protons and neutrons, you can think of Quarks that have an intense attraction to one another. That is the strong force that's carried by gluons.
Quarks are 2/3 or -1/3 charge, and come in three's. Two will be the same and one will be different. The weak force, carried by the respective +/-W and Z bosons, and work to swap one of the two identical quarks. This creates the two states one balanced(2/3,-1/3,-1/3 sum =0) and the other unbalanced(2/3,2/3,-1/3 sum=1). Balanced is the nuetron, unbalanced state is the proton. This is where the positive charge of the proton and electromagnetic force comes from. This is why it was combined and called the electroweak force.

 

[vcsharp2003]

I think that article just replace the "virtual particle exchange" with a somewhat muddy concept of "disturbance". The part highlighted by Drakkith is the message you should take home.Interacting scalar QFT is enough :-) For instance interaction terms like $\lambda \phi^3$ is enough to construct a toymodel where you can compute tree-level scattering matrixelements and cross sections (sure you would encounter problems like renormalization etc beyond tree level)
No need to invoke fermion and gauge fields :-)

But, wouldn't the Math in Quantum Physics that you have mentioned, be a bit too advanced for a high school student in Grade 11 or 12? Maybe the disturbance analogy might give some idea to such a student.

Also, what does the acronym QFT stand for?

 

[malawi_glenn]

But, wouldn't the Math in Quantum Physics that you have mentioned, be a bit too advanced for a high school student in Grade 11 or 12? Maybe the disturbance analogy might give some idea to such a student.

Also, what does the acronym QFT stand for?

QFT: Quantum Field Theory

Yeah the math is too advanced.
Problem is, that if some of these analogies are taken too literally, one can become severely hindered later on when it is time to learn these things "for real". Also it is why it is hard to distinguish crackpot "theories" (which seldom has some math in them). And they pop up here on a weekly basis: https://www.physicsforums.com/threads/disturbance-of-fields-creates-particles.1044615/#post-6789029 I bet that "idea" came from reading this thread.

This is one of the best intro QFT "visualizations"
it does not deal with interactions though.

 

[MRMMRM]

Before and after a scattering event in a dilute gas or a particle collider ring, particles can be
considered as being essentially free. During the very short interaction time itself, the scattering
process cannot be described by a particle picture. This is what I meant by it gets statistical/ probable,
because its ok to think of these things as particles as they approach each other. Its just defining when
the collision starts and ends that you need to do in QFT or quantum statistical mechanics.
Thats what Feynman diagrams imply by having time as one of the axis. They don't actually predict anything, just show that the collisions are not like billiard balls at all. When particles collide the paths they take appear random, but are actually highly probablistic when pre-collision conditions are defined. So "force" carrying particles like photons simplify thinking about these collisions.