If they are not elementary, it is probably at a scale where they are revealed to be a string theory excitation, a quantum black hole. Light is not made of anything else, neither is gravity. In my eyes, there is indeed no throwback (although I wrote it) because I'm convinced the theory is on the right track. Protons + neutrons composes an atom core, aka. They bear the name of the great Italian physicist Enrico Fermi who made a first theory of them around 1930. Should we leave technical astronomy questions to Astronomy SE? They have no electrical charge, very little mass, and they are very hard to find. String theory considers them as vibrating strings, again with no internal constituents. How do we know atoms are formed from protons and neutrons? The study of the interaction products organized the particles and resonances into what is now called the standard model, a grouping in families that have a one to one correspondence with the hypothesis that the hadrons (protons neutrons resonances) are composed out of quarks. We have the results from painstaking experiments that showed us once more that deep inelastic scattering shows a hard core inside the protons and neutrons. Electrons and positrons are *not* made up of quarks. Quarks are probably not made of anything more fundamental. Last, you have the non-standard theories. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why was the name of Discovery's most recent episode "Unification III"? I think my wording has been careful enough, but do the word "stablished" really induces such confusion, even with an "arguably" and a "not mainstream" remark in the same parragraph? Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. With only two elementary fields, the T-rishon, and the V-rishon, a preon theory can't get more economical (it's impossible to construct the until now known elementary fields out of just one field). “Question closed” notifications experiment results and graduation, MAINTENANCE WARNING: Possible downtime early morning Dec 2/4/9 UTC (8:30PM…. Do you think that the answer is not useful? The standard mode considers quarks and leptons as elementary point particles with no constituents. It maybe we will simply have to wait for further technological ingenuity before we can properly address physics beyond the SM, and this by the looks of it, could be some wait. Without preons, string theory could be also an answer but not in the line of your question; quarks and leptons would be equivalent to some string states, so not "made of", but "same as". At any rate, the question isn't exactly deep. The standard mainstream answer is to consider them as fundamentals. @FrankH, yep I say "not mainstream". What are Quarks made of and will they ever decay to this? Quarks and leptons. That atoms had internal stuff going on was obvious, because they are electrically neutral, and yet scatter light at definite magic frequencies. Leptons do … The Standard Model > What is the world made of? Leptons do not … Like I wrote in the comment below: To me, the Higgs-mechanism is a rather artificial construct and therefore I'm inclined to say that the evidence for the Higgs is contaminated. Both rishons are massless, but when they form bound states (the only state they can be in), then maybe the force (the one conveyed by hyper color gluons) between them is thát big that they can (despite the velocity of light they travel with) stay together and form massive fields. The LHC is scattering protons on protons, i.e. The quarks, on the other hand, along with the electrons, light, gravity, and the gluons and W and Z bosons, are perfectly elementary, in the sense that their interactions are described well by a renormalizable quantum field theory. So atoms are formed from protons and neutrons, which are formed from quarks. We don't know what quarks are made up of, it maybe that we've touched bottom here, or that further structure is yet to be uncovered. A very plausible guess though is contained in Harari's Rishon theory (which already has been mentioned in a previous answer), which can account for all reactions between elementary fields (except the ones that involve the Higgs field). Can someone be saved if they willingly live in sin? The code that I write in the Arduino IDE does not work, My strands of LED Christmas lights are not polarized, and I don't understand how that works, How can I label staffs with the parts' purpose. Feynman I think had said: "to see what a watch is made of one does not throw one watch on another watch and count the gears flying off. Like beads in a chain, you may design their interactions so that their bound states will be physically equivalent to strings when you're finished. Neutrons and protons betrayed their non-elementary structure because of their magnetic moments and too-strong scattering at short distances. quarks; electron-like particles called leptons. These theories usually worry a lot about gravity. What makes them? How do we know that protons and neutrons are formed from quarks? Quarks behave differently than leptons, and for each kind of matter particle there is a corresponding antimatter particle. Due to the gluon exchanges it is hard to see how a hard core might appear in quark quark scattering to take the onion one level lower, i.e. Has the Higgs interaction been observed perhaps or the vacuum expectation value directly measured?