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[Steve3007]

Particle (Wikipedia):

In the physical sciences, a particle is a small localized object to which can be ascribed several physical properties such as volume or mass. The word is rather general in meaning, and is refined as needed by various scientific fields.

Whether objects can be considered particles depends on the scale of the context; if an object's own size is small or negligible, or if geometrical properties and structure are irrelevant, then it can be considered a particle. For example, grains of sand on a beach can be considered particles because the size of one grain of sand (~1 mm) is negligible compared to the beach, and the features of individual grains of sand are usually irrelevant to the problem at hand. However, grains of sand would not be considered particles if compared to buckyballs (~1 nm).

The concept of particles is particularly useful when modelling nature, as the full treatment of many phenomena is complex. It can be used to make simplifying assumptions concerning the processes involved.

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I've quoted this same Wikipedia definition before in a previous attempt to discuss the way that this concept, and other models, are used in the physical sciences. It seems to me a good start. So let's try again! The particular physical science about which I am most comfortable speaking is physics, so I'll confine myself to that subject for now.

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The physical world is hugely complex and interactive. Everything has some kind of effect on everything else. And there are countless billions of "things". If I wanted to attempt to calculate the exact motion of any object then I would, in principle, have to account for the gravitational, electromagnetic and other influences on that object of every other piece of matter in the universe. Clearly this is impossible.

But, rather than give up and say that nothing is predictable at all, we use a method called "reductionism" to try to at least partially understand and predict the behaviour of nature. Reductionism means, essentially, ignoring some things. Actually, it means ignoring most things. Actually it means ignoring almost everything!.

Take, for example, the calculation of the motion of an object falling freely towards the surface of the Earth. In this calculation we typically ignore:

1. The gravitational, electromagnetic and every other force of every object in the entire Universe except the object being considered and the Earth.

2. All forces, except gravity, acting between the object and the Earth.

3. The shape and mass distribution of the Earth.

4. The shape and mass distribution of the object.

In other words, we treat the problem as one of two infinitesimally small points (particles) with, therefore, zero volume, infinite density and finite mass moving freely in a vacuum. When expressed like this, it may seem crazy. But it works! It gives an accurate enough result for many purposes. So reductionism is very useful. We literally could not live without it.

An essential feature of reductionism is the concept of "models". A model is an imaginary piece of the world which possesses only a small subset of the properties of the real thing. One such model is "particle". The most obvious piece of reality missing from the concept of a particle is physical extension. A key simplification in the particle concept is that it is used whenever we think that physical size is a small enough consideration to be ignored.

So, to answer the question. A particle is a model of some aspects of the natural world. It is very useful.

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I presume that any discussion which follows will go into the ways in which the particle concept has been used (and, some will no doubt claim, abused) in real life physics. But, in any such discussion, I think it's important to remember that this idea of a particle being a model is crucial. And it's important to remember that all physicists implicitly understand this, even if it is not reflected in their day-to-day language about particles and other models.

[Xris]

Hello Steve, I will try abide by certain scientific reasoning but excuse me if take the philosophical route on occassions.

What if a particle in scientific terms is described as having no mass, is it still considered a particle?

What if it never acts like a particle can it be still described as a particle?

My problem as you have realised by now is that I do not believe certain particles exist. As a concept that attempts to explain certain observations it can in technological terms be extremely useful if not essential. I would never doubt the flow of electrons when I was measuring the current flow in a circuit. My colleagues would have had me committed. I even accepted that current flow of electrons did not flow in the conventional manner. But is the reality of considering an electron as a particle not delaying our understanding of the quantum world. Firing electrons at two splits we are told has strange consequences but what if we are not firing electron particles? what if the concept is wrong and we are making assumptions and forming the wrong conclusions?

If matter is energy, we must at some point accept that energy can be expressed as something other than a particle. Electrons are waves or particles, we are told, but what if they are neither but some kind of electromagnetic radiation formed from the nucleus of atoms. It would explain the strange duality the supposed electron exhibits. I am not against the idea that science has to express its findings using the term particles but I am when the concept defies explaination.

Where energy is energy and where it becomes expressed as matter is the point where I accept particles exist but to form all our understanding of the quantum world as if it was constructed of these particles with or without mass is in my humble opinion a very ill conceived concept.

[Steve3007]

What if a particle in scientific terms is described as having no mass, is it still considered a particle?

It depends if the concept of a particle is useful in describing it. Photons have no mass, but have some particle-like properties. For example, they have intrinsic angular momentum, or "spin". (That is to say, it is useful to think of them as having something analagous to what we think of as spin for the purpose of describing certain aspects of their behaviour and the way in which that behaviour seems to have similarities, or symmetries, with other types of particles, which also seem to have spin). The higher the frequency/shorter the wavelength of the EM radiations, the more particle-like they seem to be. Gamma photons are much more particle-like than radio wave photons. In other words, the particle model is more useful for describing the observed behaviour of gamma photons than it is for radio waves. So much so that we rarely talk about "radio photons" at all. Radio waves can generally be described quite accurately using only classical electromagnetic theory - Maxwell's equations.

What if it never acts like a particle can it be still described as a particle?

No. The whole point of a model is that it possesses some of the properties of the set of observations that it is designed to describe. If it possesses none of those properties then it's no good as a model!

My problem as you have realised by now is that I do not believe certain particles exist.

Do you mean that there are some phenomena in physics that are often described using particle models that you consider to be wholly inappropriate? Where other models can be used to make more accurate predictions of observations? If so, which ones?

Or is it that there are certain symmetries in the standard model of particle physics that lead to the predicted existence of some particle-like objects which have not yet been discovered and that you believe, for reasons of your own, will never be discovered?

I even accepted that current flow of electrons did not flow in the conventional manner.

That's not surprising as there's nothing mysterious about it. The phenomenon of electric current was discovered before the mechanism for that current, the electron, was discovered. The person who arbitrarily decided on the direction of electric current had a 50/50 chance of getting it right. He got it wrong! C'est la vie. It's just one of those historical curiosities. Maybe it would have been better, on discovering the electrical properties of electrons, to reverse the conventional direction of electric current to fall into line with the direction of electron flow. But it was too late. It would have caused too much short-term confusion and inconvenience. So, like the QWERTY keyboard and driving on the left, it remains.

Firing electrons at two splits we are told has strange consequences but what if we are not firing electron particles?

I think you're still thinking in the mindset that an electron "is" or "is not" a particle. We are firing electrons. Whether we assume ourselves to be firing particles is entirely dependent and whether the consequences of that assumption are useful in making predictions about the observed behaviour of those electrons.

what if the concept is wrong and we are making assumptions and forming the wrong conclusions?

This question has been considered over and over again from every possible angle. I really don't think anyone is hung up on the idea of electrons "being" particles to the extent that they ignore evidence.

If matter is energy, we must at some point accept that energy can be expressed as something other than a particle.

It already can, if such an alternative model is useful for predicting observations. Energy is frequently described without recourse to the particle concept. The kinetic energy of a moving object, for example, is not usually described using any reference to the particle model.

Electrons are waves or particles, we are told

Not quite. You're still using that "are/is" word! Electrons appear to behave in such a way that two of the possible chunks of mathematics that can be usefully used to describe some aspects of that behaviour are the particle model and the wave model. Electrons are electrons.

but what if they are neither but some kind of electromagnetic radiation formed from the nucleus of atoms.

If you think you can construct a model like that which predicts observations better than current models then by all means describe or publish it. But it doesn't seem likely that electrons are EM waves emitted from atomic nucei because they don't have any of the properties of such waves. Both EM waves and electrons are in fact emitted by atomic nuclei, along with other things like helium nuclei (alpha particles). Gamma rays/particles are EM photons emitted by atomic nuclei. Beta rays/particles are electrons emitted by atomic nuclei. They appear to have completely different properties. For example, beta particles, being electrically charged, are deflected by a magnetic field, they have different intrinsic spin (see the Stern Gerlach experiment) and they travel at different speeds.

But if you can think of some other model, perhaps involving waves or something else, which you think more accurately describes the observed properties of electrons and other things than current models, then describe it!

I am not against the idea that science has to express its findings using the term particles but I am when the concept defies explaination.

I don't really see how the particle concept "defies explanation". The Wikipedia article I quoted in the OP seems pretty good. Perhaps you could try to define what exactly it is that you think defies explanation? Is it the observed behaviour of things like electrons?

Where energy is energy and where it becomes expressed as matter is the point where I accept particles exist but to form all our understanding of the quantum world as if it was constructed of these particles with or without mass is in my humble opinion a very ill conceived concept.

Again, all I can say is that if you can think of a concept that is more well-conceived; that better describes the evidence, then go for it.

Remember, "particle" is just a word. The real language of physics is mathematics because mathematics is the most precise and logically consistent way that anyone has so far found of describing physical things. The so called "standard model of particle physics" which essentially incorporates everything except gravity, obviously uses the word particle a lot. But it's really just a convenient label for a whole set of mathematical rules. The standard model unites the strong and weak nuclear forces and the electromagnetic force into one framework. As is required by any superceding scientific theory, it contains previous correct theories as special cases. So it contains Newtonian mechanics, Special Relativity and Maxwell's equations - the pillars of classical physics, as special cases. i.e. it reduces down to those theories in particular circumstances. So far, in terms of predicting observations, it has been very successful.

But, as I said, it doesn't include gravity (i.e. General Relativity) so it's most certainly not complete. If you can think of a better, more complete, model then that would be great, whether or not your model uses the particle concept or any other concept.

[Xris]

Thanks Steve It will take a while to digest and make a reasoned response.

-- Updated Wed Apr 11, 2012 2:30 pm to add the following --

Steve I recently found a cranky guy called Bill Gaede. I am not sure if I can fully agree with his arogant representation of his theory but he has put some interesting thoughts into my head. I must be cranky also because a lot of what he is saying rings familiar bells. If you find him, try looking past his strange representation. Electrons, photons, light, he describes as EM ropes of varying frequency, connecting atoms. I must admit since talking to you last I have watched more of videos. I am a little confused but amazed. I would be interested in your views of his proclaimed theories as I am not in position to actually question all he has to offer.

[Wayne92587]

A single grain of sand on the beach would be a particle of sand, relatively speaking, has no quantity, no Mass.

A piece of gravel in gravel pit would be a particle of gravel in a a gravel pit, relatively speaking, has no quantity, no Mass.

A Piece of gravel on the beach, relatively speaking has quantity, mass.

The Particle you speak of is relative in quantity, mass, to the Whole of the Universe, the Whole of the Reality of Everything.

If the particle you are speaking of is subject to the Reality of Physical Universe, Physical Science, you must be speaking of the Most Minute Particle in existence, in the Universe.

The minutest particle in the universe being an individuality, an Infinitely Finite Indivisible Singularity having no relative, numerical value, said Singularity not being accurately measurable as to Location and momentum in Time and Space; the Motion of said Singularity being meaningless, existing without displacement, being liken to a Vibration and Oscillation, resulting in a Singularity alone in the Emptiness of Time and Space making a Humming Sound.

[Xris]

When is a particle not a particle?

[Wayne92587]

Particle; 1.a minute portion, piece, fragment, or amount; a tiny or very small bit: a particle of dust; not a particle of supporting evidence.

2.Physics. a. one of the extremely small constituents of matter, as an atom or nucleus. b. an elementary particle, quark, or gluon. c. a body in which the internal motion is negligible.

The word paticle is to generic to say when a particle is not a paticle.

As far a I see it the term particle should be limited to being defined to be the minutest object in the universe, an infingitely finite inidivisible Singularity, having no relative, numerical, value, having a numerical Value of Zero--O, Nada, Zip.

[Xris]

Particle; 1.a minute portion, piece, fragment, or amount; a tiny or very small bit: a particle of dust; not a particle of supporting evidence.

2.Physics. a. one of the extremely small constituents of matter, as an atom or nucleus. b. an elementary particle, quark, or gluon. c. a body in which the internal motion is negligible.

The word paticle is to generic to say when a particle is not a paticle.

As far a I see it the term particle should be limited to being defined to be the minutest object in the universe, an infingitely finite inidivisible Singularity, having no relative, numerical, value, having a numerical Value of Zero--O, Nada, Zip.

So does it require mass? I am constantly told that if a particle exhibits a value equal to a particle it is a particle but it does not necessarily is a particle. Quantum has a serious problem in defining what constitutes a particle.Photons have no mass and can be created moving at the speed of light with no apparent direction. They are only presumed to exist simply because nothing else fits the description. Electrons are even faster than photons but they have mass. Now that is amazing. Gravitons, those mysterious particles that no one has found but must exist, must they?

Do you really believe this minute world is filled with little atoms surrounded by little pesky electrons buzzing round them? That these strange ever smaller particles are made of smaller and smaller particles where we can constantly divide them. But mass is energy and energy is mass so when is energy expressed as mass? What is energy? What is pure energy? How can pure energy be expressed as mass and give us something to touch and smell? We need to reexamine our views, listen to sages and mad men and not to look dogmatically at what we have previously accepted.

[DanLanglois]

Remember, "particle" is just a word. The real language of physics is mathematics because mathematics is the most precise and logically consistent way that anyone has so far found of describing physical things

I don't think this grapples with why the real language of physics is mathematics. The real language of all science is mathematics. I suppose it sounds plausible to say that mathematics is logically consistent, but actually, being logically consistent is not hard, I don't think this demarcates mathematics. 'Precise'. What is precise about it? That 9.9999 is greater than 9.999 in mathematics, perhaps. But if we have numbers at all, we're doing mathematics already. What are numbers, really? Precise and logically consistent, that doesn't seem to me to really capture it. I'd get into how numbers are constructed by us, using time and space. They have no, as is said, 'extensional' existence.

So does it require mass? I am constantly told that if a particle exhibits a value equal to a particle it is a particle but it does not necessarily is a particle.

Well, obviously, this is a bit garbled.

Quantum has a serious problem in defining what constitutes a particle.

Quantum has a definition of what constitutes a particle, and there's no debate about it, I would have said, which is the opposite of your point.

Photons have no mass and can be created moving at the speed of light with no apparent direction. They are only presumed to exist simply because nothing else fits the description.

'Presumed to exist'. Postulated, shall we say? Sure, and why not?

Electrons are even faster than photons but they have mass.

I must have lost the thread. Photons travel at the speed of light. So, there is nothing faster.

Now that is amazing.

It would be. Might be. I think you're mistaken?

Gravitons, those mysterious particles that no one has found but must exist, must they?

There's room for serious doubt about gravitons, they haven't been observed. Fastidious reminders that this is just a theory sometimes are skipped, but the big picture is that it is known that there are serious, crippling problems with quantum theory.

Do you really believe this minute world is filled with little atoms surrounded by little pesky electrons buzzing round them? That these strange ever smaller particles are made of smaller and smaller particles where we can constantly divide them. But mass is energy and energy is mass so when is energy expressed as mass? What is energy? What is pure energy?

Energy is made of energy. It's defined operationally. It's measured. The same could be said of heat. Heat is made of heat. The point that these are geometrical constructs is rather profound, I think, but I'm not sure that it's your point here.

How can pure energy be expressed as mass and give us something to touch and smell? We need to reexamine our views, listen to sages and mad men and not to look dogmatically at what we have previously accepted.

You can't touch and smell mass, you touch and smell matter. I think you'd like more of an answer than that, but it's something to consider.

[Stormy]

A gathering. Like all gatherings, they come and go, and leave traces of where they have been. I guess.

-- Updated August 6th, 2012, 9:12 pm to add the following --

Usually when we find a reason to something, we gain insight; and low and behold we have a new tool or toy in which to play with. For some this can benefit mankind, not all gatherings result in idle gossip, some actually make a difference. Unlike a lot of gatherings, particles make all the difference. Maybe we are not so different, one person can change many...I guess.

[Wayne92587]

Xris wrote;

I am constantly told that if a particle exhibits a value equal to a particle it is a particle but it does not necessarily is a particle.

Interpreted by Wayne; I am constantly told that if a particle exhibits a value equal to a particle it is a particle but it is not necessarily a particle.



The problem with Particles is greater than you can imagine.

A Particle is Particle; however, the innate motion of a Singular Particle alone in the Emptiness of Time and Space, although fully random, boundless, is so negligible as to be meaningless; a Singular Particle existing without displacement, without angular momentum, without velocity of speed and direction, not being measurable as to location and momentum in Time and Space, having no relative, numerical value, having a numerical value of Zero-O; the existence or non-existence of a Singular Particle having a numerical value of Zero-O being being eternally uncertain.

The existence or non-existence of a Singular Particle exhibiting a numerical value equal to a particle having no relative value, having a numical value of Zero-O, is a Particle but not necessarily a particle; at least not if it can be shown that a Singularity Particle having no relative, numerical value, having a numerical value of Zero-O does not exist.

[DanLanglois]

Supposing that atoms and sub-atomic particles are not small balls that bounce around, or behave like anything you see in the everyday world. Is this a great problem? Suppose that we stipulate, that our everyday intuition will not help us on that tiny scale. Nevertheless, the standard model theory can mathematically describe all the characteristics and interactions that you see for these particles.

While I'm referring to the standard model, here's a bit of a summary. It is a simple and comprehensive theory that explains all the hundreds of particles and complex interactions with only: 6 quarks. 6 leptons. Force carrier particles, like the photon. All the known matter particles are composites of quarks and leptons, and they interact by exchanging force carrier particles.

A good theory, but gravity is not included. *For Example*. It does not explain everything.

[Xris]

Particles are fine if they answer all the questions and anomalies their concept invites but they don't.Particles have bred an indeterminate universe, Big Bangs, dark matter,multi universes, black holes. They all are dependant on the concepts of a particle. I will ask again, when is particle not a particle?

[Wayne92587]

Particle is a catch all term, a Particle being the minutest indivisible singular particle that is measurable as to location within a particular State or Condition of a Whole, of a Mass, of a quantity of whatever substance; a grain of sand relative to a mass, a quantity of sand would be a particle of sand, the relativity of a grain of sand, a particle of sand, to a mass, a quantity of sand being taken for granted, being a universal truth; a grain of sand having no relative value has a numerical value of Zero-O.

A Singular Particle having a relative, numerical value of Zero-O, unless it is the first in a series, is exists as part in part of a greater whole, the first in a series; as the beginning of a continuum, a Singular Particle then having a relative, numerical value of One-1.

A particle relative to the particular state or condition in which Whole of Reality, the Heavens and the Earth, the Physical Universe, the Material Reality of Everything that exists within the Infinite Emptiness of Infinite, Immeasurable Space, relatively speaking would be an Infinitely, an Immeasurable, Finite Indivisible Singularity; a Particle existing without being relative, having numerical value of Nothing, Nada, Zip, Zero-O within the Reality of a Steady, Static, Quantum State of Singularity.

The existence or non-existence of a Particle is however uncertain due to the fact that an Infinitely Finite Indivisible Particle is not measurable as to location in the Emptiness of Time and Space, a Singular Particle not being subject to the relativity of Time and Space, cause and effect

The negligible innate Motion of a Singular Particle alone in the emptiness is meaningless, the existence of a Singular Particle having a relative, numerical value of Nothing, Nada, Zip, of Zero-O.

The existence or non-existence a Singular Particle being uncertain because the motion there of, not being relative, having a numerical value of Zero-O, exists without displacement, without angular momentum, without velocity of speed and direction is not measurable as to location and momentum in Time and Space, is not readily apparent.

The Innate Motion of a Singular Particle alone in Emptiness of Infinite, Immeasurable, Space, being so negligible that both a Singular Particle and its Motion, even though being Fully Random, Boundless is Meaningless; the definition of Singular Particle to include both the negligible Innate Motion and the Infinitely, immeasurable, Finite Indivisible Particle itself.

Because Singular Particle exists without displacement, without angular momentum, without velocity of speed and direction, neither the negligible motion nor the Singular Particle itself having relative, numerical value, the Relative and the Numerical value of both the Singular Particle and the negligible innate motion there of having relative, numerical value of Zero-O.

[Dr Jonathan Osterman PhD]

So, to answer the question. A particle is a model of some aspects of the natural world.

So, the question is: What are these aspects of the natural world, which we try to model?


WHAT IS A PARTICLE ?

Prof. Netta Engelhardt, a physicist at MIT who won a New Horizons in Physics Prize for calculating the quantum information content of black holes, admits with all honesty that the short answer is:

“We don’t know.”

www .quantamagazine. org/what-is-a-particle-20201112/

Because, as you can read below, particle physicists are far from any clear consensus:

“At the moment that I detect it, it collapses the wave and becomes a particle. The particle is the collapsed wave function.” — Dimitri Nanopoulos

“What is a particle from a physicist’s point of view? It’s a quantum excitation of a field. We write particle physics in a math called quantum field theory. In that, there are a bunch of different fields; each field has different properties and excitations, and they are different depending on the properties, and those excitations we can think of as a particle.” — Helen Quinn

“Particles are at a very minimum described by irreducible representations of the Poincaré group.” — Sheldon Glashow

“Ever since the fundamental paper of Wigner on the irreducible representations of the Poincaré group, it has been a (perhaps implicit) definition in physics that an elementary particle ‘is’ an irreducible representation of the group, G, of ‘symmetries of nature’.” — Yuval Ne’eman and Shlomo Sternberg

“What we think of as elementary particles, instead they might be vibrating strings.” — Mary Gaillard

“Every particle is a quantized wave. The wave is a deformation of the qubit ocean.” — Xiao-Gang Wen

“ ‘Particles’ are what we detect in detectors. We start slipping into the language of saying that it’s the quantum fields that are real, and particles are excitations, but it does not go click, click, in anyone’s detector.” — Nima Arkani-Hamed


www. quantumantigravity.wordpress. com/hopfotrino/