# What is a subatomic particle?

Kenneth Boon Faker
A subatomic particle can either be a wave or a particle.

When it is a particle, what actually is it? is it literally like a tiny physical ball rattling around? (If not, then what is it?)

And when it is a wave, what is it?

From my understanding, when a particle behaves like a wave, the physical particle loses its matter and position in space. It makes a transition into a non-empirical part of the world?

Your help would be much appreciated,

Thanks,
kenny

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A subatomic particle can either be a wave or a particle.
This is not correct and just something that you will often read in popularised texts. A particle is not "either a wave or a particle", what we deal with and call "particle" in particle physics are objects that have some properties that are reminiscent of those of a classical particle and some that are reminiscent of a classical wave. Which ones are most clearly seen in a given experiment depends on the experimental setup. The "wave particle duality" has been obsolete for ages.

When it is a particle, what actually is it? is it literally like a tiny physical ball rattling around? (If not, then what is it?)
As I already stated, it "is" not a particle or a wave. It has some particle properties, such that its energy and interactions can be in the form of localised quanta.

And when it is a wave, what is it?

From my understanding, when a particle behaves like a wave, the physical particle loses its matter and position in space. It makes a transition into a non-empirical part of the world?
Fundamentally the question "what is it" is rather philosophical and not really scientific. The wave properties that a particle relate to wavelength, interference patterns, etc. The "wave" describes the probabilities of the energy quanta of being delivered at different positions and in different ways.

transition into a non-empirical part of the world?
What do you mean by "non-emprirical"? Quantum mechanics has been used very successfully to do empirical science. Is "non-deterministic" the word you were looking for?

sophiecentaur and Dale
Mentor
A subatomic particle can either be a wave or a particle.
It is always a quantum particle, but a quantum particle is not a little ball zipping around.

sophiecentaur
rootone
Particles are features of quantum fields.
The field is always everywhere.
Particles exist with some amount of probability at different locations in the field.

sophiecentaur
Kenneth Boon Faker
This is not correct and just something that you will often read in popularised texts. A particle is not "either a wave or a particle", what we deal with and call "particle" in particle physics are objects that have some properties that are reminiscent of those of a classical particle and some that are reminiscent of a classical wave. Which ones are most clearly seen in a given experiment depends on the experimental setup.

Good stuff. I follow this so far.

The "wave particle duality" has been obsolete for ages.

What do you mean by this? Could you expand please?

As I already stated, it "is" not a particle or a wave. It has some particle properties, such that its energy and interactions can be in the form of localised quanta.

Yes, I can follow that. Thanks.

Fundamentally the question "what is it" is rather philosophical and not really scientific.

You're right, it is rather philosophical. But physics is under the umbrella of science, and one of science's aims is to understand the essential nature of all things. From my understanding, quantum theory deals with the fundamental building blocks of nature - perhaps the 'bottom layer' of reality - so at some point physicists must entertain the question "what is it?" From this, I'd conclude that the question is scientific.

The wave properties that a particle relate to wavelength, interference patterns, etc. The "wave" describes the probabilities of the energy quanta of being delivered at different positions and in different ways.

To me, this sounds like the particle enters a realm of information and mathematics. Is this not a dimension of non-material forms? Please correct me if you think I'm off the ball, or if you have a clearer way of describing it.

What do you mean by "non-empirical"? Quantum mechanics has been used very successfully to do empirical science. Is "non-deterministic" the word you were looking for?

Non-deterministic is one way of describing it. But it appears to me that the building blocks of everything that exists only have 'tendencies' or 'probabilities' to exist as physical matter with a position in space? These building blocks seem to have their roots in a non-physical field of some kind?

Kenneth Boon Faker
It is always a quantum particle, but a quantum particle is not a little ball zipping around.

What is it then? I am off the ball concluding that it is "energy"?

Particles are features of quantum fields.
The field is always everywhere.
Particles exist with some amount of probability at different locations in the field.

I can't help thinking of this field consisting of pure energy, or some kind of realm of information and mathematics?

rootone
...some kind of realm of information and mathematics?
Statistics.

Mentor
The "wave particle duality" has been obsolete for ages.
What do you mean by this? Could you expand please?
"Wave particle duality" was one of the ideas that were introduced very early last century when quantum phenomena were first observed and we had no satisfactory theory for explaining them. It turned out not to be especially helpful, and was abandoned in the 1920s when the modern theory of quantum mechanics was developed. You won't find it (except as a historical footnote) in any serious explanation of QM.

Unfortunately by then the idea had captured the popular imagination so it survives to this day as a sort of urban legend, one of those things that everyone has heard and repeats as fact.
To me, this sounds like the particle enters a realm of information and mathematics. Is this not a dimension of non-material forms?...Non-deterministic is one way of describing it. But it appears to me that the building blocks of everything that exists only have 'tendencies' or 'probabilities' to exist as physical matter with a position in space? These building blocks seem to have their roots in a non-physical field of some kind?
It is a historical accident that we use the word "particle" for quantum objects even though they do not behave at all like little bullets or very small objects or anything else that the word seems to suggest. Nonetheless, we have a satisfactory and rigorous theory for them, and learning it is a necessary first step towards understanding what they are.

Mentor
What is it then? I am off the ball concluding that it is "energy"?
Again, it is a quantum particle. It isn’t anything else. It has energy, but it also has other properties, such as spin, charge, etc.

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You're right, it is rather philosophical. But physics is under the umbrella of science, and one of science's aims is to understand the essential nature of all things. From my understanding, quantum theory deals with the fundamental building blocks of nature - perhaps the 'bottom layer' of reality - so at some point physicists must entertain the question "what is it?" From this, I'd conclude that the question is scientific.

The other parts have been answered by others so let me just reply to this as it is a misconception of what "scientific" means. Empirical science is an endeavour directed towards describing how the world works. There is no deeper pursuit and philosophical questions such as what things "really are" do not belong. A scientific statement must be falsifiable. In other words, you must be able to rule it out with observations. All science can tell you is what the "best description we have at the moment" is.

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one of science's aims is to understand the essential nature of all things
I don't think any true Scientist actually thinks in terms of 'getting to the absolute truth' of things. Science is more of a process of continual improvement with no actual aim in view.
It is a historical accident that we use the word "particle" for quantum objects even though they do not behave at all like little bullets
I think Feynman has to take his share of the blame for this 'accident'. I am sure that he knew exactly what he meant when he was so liberal in his use of the P word when talking about Photons but he was such an engaging and convincing teacher that he left several generations of students with a far more literal picture than he intended, of the things he called "Particles".
Even his Feynman Diagram is taken way beyond it's symbolic purpose and that also gives many students problems. But I guess someone with a brain the size of a planet cannot always be expected to second guess how his statements will be taken by us mere mortals.

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Kenneth Boon Faker

To me, the following quote is valid and apt in the field of quantum theory. Would you agree, or can you see any flaws in the statement? :
In 1856, inventor Nikola Tesla said, "If you want to find the secrets of the universe, think in terms of energy, frequency, and vibration."

Greg Bernhardt
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so at some point physicists must entertain the question "what is it?" From this, I'd conclude that the question is scientific
Yes, but the answer is “it is a quantum particle”. And a more detailed answer would be “quantum particles are things that are measured to behave according to the predictions of the equations of QFT”. The scientific answer would not involve any analogies or shortcuts but a reference to the theory and experiments.

sophiecentaur
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To me, the following quote is valid and apt in the field of quantum theory. Would you agree, or can you see any flaws in the statement? :
In 1856, inventor Nikola Tesla said, "If you want to find the secrets of the universe, think in terms of energy, frequency, and vibration."
That's not how I learned about quantum field theory, nor can I imagine that advice helping anyone else trying to understand it. There's no substitute for studying the theory, math and all.

(Small point as well: 1942, not 1856)

Dale
Mentor
I thing Feynman has to take his share of the blame for this 'accident'
I think you overstate Feynman's influence. The P-word was being applied to subatomic particles before he was born, and was solidly entrenched in the professional vocabulary by the time he began his studies.

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I think you overstate Feynman's influence. The P-word was being applied to subatomic particles before he was born, and was solidly entrenched in the professional vocabulary by the time he began his studies.
I think his contribution to 'general knowledge' was as lot greater than you give him credit for. I think the word moved from "professional vocabulary" (where its meaning was understood) to 'general vocabulary' due to Feynman's entertaining and otherwise excellent presentation. Talk to most people who have a fair knowledge of elementary Modern Physics and they will be sure to quote Feynman as a source of their knowledge. I think he will soon be back up there with Hawking as a source of popular Science knowledge.
He doesn't need to be defended as the net gain in education from him is not in doubt.

In my opinion, the wave-particle duality is a very useful tool in quantum mechanics if used correctly, which is what I will attempt to explain in this post. As noted many times in this thread, the wave-particle duality is incorrect if we are talking about what the particle “is” as a quantum particle is not classical in any way. Describing a quantum particle as “being” a combination of two classical things, i.e. a classical wave and a classical particle, is thus completely incorrect. We logically, of course, name these things “particles” seemingly in an attempt to confuse people trying to learn physics (as has been noted many times, this name is a historical mistake).

What, I would argue, should keep this wave-particle duality notion around is when talking about properties. We can connect many properties of a quantum particle to classical particles or to classical waves. Note that these are just merely analogies to allow us to wrap our heads around quantum mechanics. It is true that quantum particles share many properties with different classical objects, but this is not to say that are a combination of those objects. Sometimes, though, depending on the problem we are trying to solve, the wave-like properties or the particle-like will become very important, to the point that mathematically, we can treat it much like one of those classical particles. This, again, is not to say it is one or the other at that time, just that in our problem or experimental setup, we are trying to bring out one of these properties. The quantum particle still retains all of its quantum properties, and does not “become” either a particle or a wave, it merely acts like it because we are, in a way, manipulating it to do that. Still, in no way, is it a classical ball bouncing around everywhere, or a classical wave (though it may act like it). Hopefully you understand here that we are not talking about what it is, but what it acts like in certain situations.

This kind of labeling, unfortunately, appears more than once in quantum mechanics. For example, we like to say that an electron has something called spin. Though, in a way, the electron acts as though it is a little spinning ball, very few people actually think the electron is spinning like the Earth. This is, again, a historical mistake. Although, I should point out, we can’t say for sure that it’s not really spinning, just that we don’t think it is. Naturally, we label that property as spin ;).

Kenneth Boon Faker
depending on the problem we are trying to solve, the wave-like properties or the particle-like will become very important, to the point that mathematically, we can treat it much like one of those classical particles. This, again, is not to say it is one or the other at that time, just that in our problem or experimental setup, we are trying to bring out one of these properties. The quantum particle still retains all of its quantum properties, and does not “become” either a particle or a wave, it merely acts like it because we are, in a way, manipulating it to do that.

But this makes the definition of a particle even more blurred. To say that a subatomic particle is both a wave and a particle at the same time doesn't make a great deal of sense?

But this makes the definition of a particle even more blurred. To say that a subatomic particle is both a wave and a particle at the same time doesn't make a great deal of sense?
Precisely, which is why I said it is not both a wave and a particle at the same time. It merely acts like it. A quantum particle is NOT a classical particle, a classical wave, or some combination of the two. It is it’s own thing. The wave-particle duality, in my opinion, just points out that sometimes it works to think about it as some combination of the two, as in certain situations, it acts like it is.

Kenneth Boon Faker
rootone
But this makes the definition of a particle even more blurred. To say that a subatomic particle is both a wave and a particle at the same time doesn't make a great deal of sense?
Because a subatomic particle is a quantum object, it is neither a wave or a particle in the classical sense.
When measuring quantum particles they can exhibit wavelike properties or particle-like properties depending on the measuring method.
There is no measurement method in which they display both wavelike and point like behavior simultaneously.

Kenneth Boon Faker
Mentor
To say that a subatomic particle is both a wave and a particle at the same time doesn't make a great deal of sense?
Note that @Isaac0427 never said that "a subatomic particle is both a wave and a particle at the same time" nor anything similar.

Gold Member
When it is a particle, what actually is it? is it literally like a tiny physical ball rattling around? (If not, then what is it?)
And when it is a wave, what is it?
The problem with this thread is in the first paragraph of the OP. (above)
There is no answer to "what actually is it"? that involves it being near enough "like" anything. Why should it? Our Science is littered with analogies that are stumbling blocks for students because they are taken too literally. This is one of the worst.
Quantum Particles can only be described adequately in terms of the Physics that was invented specially for them: Quantum Mechanics, Quantum Electrodynamics etc..
It's too late to change now but the term 'Particle' should never have been used in this context because it carries too much baggage.

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