|MadSci Network: Physics|
Thank you Kol for your question. And a good question it is! Nuclear science is pretty recent. In the early 1900s, scientists began to discover the inner workings of the atom - the smallest component of matter. Protons & neutron in a very dense core with a cloud of electrons well outside the core. But that simple explanation was not adequate to explain all the data they were observing through experiments. Currently, the "smallest thing discovered" is wrapped up in a theory called "The Standard Model". This model flows from quantum mechanics. Max Planck (around 1900) was the first to theorize that, on the microscopic scale, energy was not continuous but rather was made of individual packets called "quanta".Anyway the Standard Model places the smallest things are quarks & leptons. Quarks make up the protons and neutrons. The electron is one of the leptons. But are these the smallest things? We're not sure. A new field of physics speculates that matter and energy may be strings -- very, very, very small 1-dimensional objects. The trouble is that the size of these strings is so small - it doesn't appear that we can actually see them. You see another part of quantum mechanics involves a contribution by physicist Werner Heisenberg who finds that on small scales - things are not too certain. In fact the Heisenberg Uncertainty Principle says that you cannot know a particle's position and momentum exactly. These strings are on the order of a Planck length (that is a decimal followed by 32 zeros and a 1). We certainly have no way to observe such a particle today and being able to even theoretically see such a particle is questionable. Is it real? Time will tell. Perhaps circumstantial evidence would point to its existance. http://superstringtheory.com/ So the smallests things: quarks which compose protons and neutrons - for the particles we can observe. Theoretically, strings - but so small we have no hope of directly observing at present.
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