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Did scientists at some point believe that everything is made out of atoms? Or were atoms always accompanied by other "elementary particles"?

I myself did not realize that there existed other "elementary particles" besides atoms until quite recently. I assumed that both solid objects, liquids, the wind blowing, fog, and light was all made out of atoms.

Apparently, at least light is not made from atoms, but "photons". While trying to determine what wind and fog is made of, I opened a metaphorical "can of worms" which caused my head to start spinning from all the cryptic and complicated Wikipedia articles, talking about numerous "elementary particles" to the point where I lost all ability to make any sense of the whole situation, as so often is the case when I try to "simply look something up".

Would appreciate if this were straightened out once and for all, both in historical and current understanding.

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  • $\begingroup$ Wind is an event, not an object - it's what happens when air moves. You could also ask what an eclipse or "going to the store" is made of, but those likewise are not things. When trying to figure out what something is made of, be sure that it's actually a thing, and not a process. $\endgroup$ – Nuclear Wang Mar 6 at 17:30
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    $\begingroup$ Three books, if you really want to dive into this topic, are: Brownian Movement and Molecular Reality (another copy) by Jean Perrin (1910; 2005 Dover reprint) AND Atoms by Jean Perrin (1916) AND especially Molecular Reality by Mary Jo Nye (1972). $\endgroup$ – Dave L Renfro Mar 7 at 9:08
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There was a time in the late 1800's-to-early 1900's when it became fairly clear that all substances in the material world were made of atoms. This "atomic theory" was not adopted by all scientists, however; there were significant holdouts for years after, and all the while the question of what an atom was actually made of was still unsettled.

Then, in the first 35 years of the 20th century it became fairly clear (again) that atoms were made of three types of subatomic particle: protons, neutrons and electrons. These are the constituents of all ordinary atoms we encounter in our everyday lives. The so-called "zoo" of other subatomic particles discovered since then in laboratory experiments are not found in ordinary matter because their lifetimes are very short, and the conditions needed to create them (extremely high temperatures & energies) don't exist except in exotic places like particle accelerators and the central core of the sun.

Photons are indeed not atoms- they are bundles of energy that have no mass and always travel at the speed of light. The interactions between photons and electrons (which are the outermost constituents of atoms) give rise to most of the ordinary properties of matter that we experience in our daily lives.

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  • $\begingroup$ While electrons play a crucial role in most interactions of matter with EM field, the nuclei shouldn't be skipped as if they only take part in nuclear reactions. Lattice absorption, for one, is an important mechanism for absorption of IR radiation. $\endgroup$ – Ruslan Feb 22 at 13:13
  • $\begingroup$ Photons have no rest mass. They do have non-rest mass. $\endgroup$ – PyRulez Feb 22 at 14:44
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    $\begingroup$ @PyRulez "non-rest mass" (dynamic mass) is a controversial interpretation and generally discouraged in current times. $\endgroup$ – electronpusher Feb 22 at 20:32
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I’ll supplement Niels’ answer by answering some of your questions that he didn’t.

Wind is mostly made of nitrogen and oxygen molecules, which make up most of the atmosphere. Nitrogen molecules have two nitrogen atoms joined together and oxygen molecules have two oxygen atoms similarly joined.

The part of fog that looks white or grey is mainly made of water molecules, which have two hydrogen atoms and one oxygen atom joined together. The water molecules are mixed in with the nitrogen and oxygen molecules that make up most of the colorless air.

The protons and neutrons in the nuclei of atoms are actually made of even more fundamental particles called quarks, held together by gluons. Specifically a proton has two “up” quarks and one “down” quark, while a neutron is the opposite. As far as we can tell today, quarks, gluons, electrons, and photons are not made of anything even more fundamental.

There is a detailed and very successful mathematical theory of elementary particles called the Standard Model. It actually has seventeen different kinds of particles, by one popular way of counting them which you can see in the diagram with 17 boxes here.

Some of the particles are fundamental but unstable and quickly decay into stable fundamental particles. Decaying into other particles does not mean that those other particles were “inside” the unstable ones. Instead, the unstable particles are able to mutate into other kinds of particles according to certain rules.

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Historically, the concept of "atoms" (from the Greek atomos, indivisible) just denoted the smallest particles of matter. Democritus and followers argued that the only things that existed were atoms and the void. The idea of subatomic particles would not have made sense to them - atoms were simply the smallest indivisible parts.

When physics in the 19th century started to discover the elementary parts of matter they often talked about them as "corpuscles" ("small bodies"). The term atom became attached to the smallest constituent of chemical elements, and then people found the electron and other particles, so the terminology got confused.

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Well, Richard feynman, did write in his first volume in his lectures on physics:

If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.

He neglected to say that such a theory had been discovered over two millenia ago, and in two places - Buddhist India and Ancient Greece. No cataclysm occured. Its merely that these were understood as the esoteric musing of so called natural philosophers, and perhaps not to be taken too seriously by the ordinary man. Thus they have led a kind of secret and underground life known only to specialists of ancient and medieval philosophy; until the rennaisance where they burst again into new life. Newton notion of a corpuscule would have been unthinkable without this prior discovery.

Moreover, these two ancient conceptions, which on the face of it are similar are also dis-similar; for example, the Greek atoms are permanent elements of reality; whereas the buddhist conception, given their notion of Pratītyasamutpāda (dependent origin or arising), is not; according to Noa Ronkin, this kind of atomism was developed in the Sarvastivada and Sautrantika schools for whom material reality can be:

reduced to discrete momentary atoms, namely, the four primary elements. These momentary atoms, through their spatial arrangement and by their concatenation with prior and posterior atoms of the same type, create the illusion of persisting things as they appear in our everyday experience. Atomic reality is thus understood first and foremost as change, though not in the sense of a thing x transforming into y.

and

That is, change itself is the very nature of atomic reality rather than its being made of enduring substances the qualities of which undergo change. Atoms that appear to endure are, in fact, a series of momentary events that ascend and fall in rapid succession and in accordance with causal relations. Unlike the atoms of the Vaifesika, the atoms of the Sarvastivada-Vaibhasika and the Sautrantika are not permanent: they come into being and cease from one moment to the next going through a process of birth, continuance, decay and destruction. Yet the material compounds that consist of these atoms are real, if only in the minimal, phenomenological sense

Thus the buddhist atoms, as described in popular book, the Tao of Physics, is much closer to the modern conception.

Moreover, it ought to be understood that atoms aren't the whole story. Aristotle certainly didn't think so, and nor did Thales and Parmenides. One might consider this the otherside of the story, the story of continua, and the way that continua carry motion is through waves.

Again, it is only in the last century that they have been understood as two sides of the same question - the question of what constitutes ontological change, that is physical.

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