Fleas on fleas: our gunky universe?Haveyou ever wondered what the smallest thing is in the Universe?

Fleas on fleas: our gunky universe?Haveyou ever wondered what the smallest thing is in the Universe? Maybe there is no such thing.We’reused to observing objects that match us in size, like tables and chairs; and wecan visually make out small’sh and big’sh objects, like grains of sand and mountains,at least with some perspective. But we have to notionalise things on an extremescale, beyond our perception—the cosmos and its fundamental parts, quarks andneutrinos and all. We use numbers with plenty of zeros to characterise them; weinfer their existences; but we don’t see them.Wemight, then, dare to imagine that the Universe is stacked infinitely: a flea ona flea’s back on a flea’s back … divided and divided with no smallest part.And so goes this wonderful poem, Siphonaptera, by Augustus DeMorgan:Great fleas have littlefleas upon their backs to bite ‘em,And little fleas havelesser fleas, and so adinfinitum.And the great fleasthemselves, in turn, have greater fleas to go on;While these again havegreater still, and greater still, and so on.Isthis possible? Some philosophers and physicists think so. The Universe, theysay, is ‘gunky’. There is no largest part either: planets and stars andgalaxies are perhaps smaller particles of an even bigger universe.Afractured universe is already commonly accepted in quantum mechanics: fields underly ‘particles’ with no defined locations. Conversely, classical physicistssee a grained universe: electrons are fundamental, indivisible particles, ~ 10^-15m in size. But this is a false move, say quantum physicists, since the Universeis funkier than that: electrons are point particles of no spatial extents.However,while quantum physicists like funk, they don’t necessarily like gunk! Their theoriesoften entail indivisible building blocks (e.g. ‘ground states’ and properties).This is also true for string theory, whose building blocks are ‘vibratingstrings’. A world that can be infinitely carved up threatens both worlds.Trueor not, a gunky universe is fantastically different to the one we think we inhabit:no smallest or largest thing, just never-ending division. -- source link

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