• Olivier5
    6.2k
    I suppose everybody knows the tale of "turtles all the way down" but here it is for the record:

    A believer in the idea that the world rests on the back of a turtle, is asked:
    - What does the turtle rest on?
    - Another turtle.
    - What does the second turtle rest on?
    - A third turtle.
    - And the third turle rests on?
    - It's turtles all the way down.

    Often, the tale is used to illustrate the falacy of the "first cause" argument for the existence of God. I want to apply it to a different topic: to modern physics and the infinitely small.

    We know, or think we know, that atoms can be broken in smaller pieces, called particles (protons, neutrons, electrons) and that these particles can be further broken down into quarks.

    The question is: could quarks be broken down in smaller pieces too? And those pieces of quarks, could they be further broken down, etc. etc. ad infinitum?

    Could there be no "bottom" to that stuff we call matter? Could it be "particles all the way down"?
  • Banno
    23.4k
    The odd thing 'bout science is, it's not just shite we make up. Imagining turtles all the way down is not enough, scientists will poke and prod the see if there are indeed tulles, and even try to show that it's not turtles all the way down.

    Chelonaut
    Chelonauts are space explorers sent under the Great A'Tuin in an attempt to discover its gender. The only known attempts were made by Krull, the only Discworld island to hang over the Rim, and were told about in The Colour of Magic. These were lowering a glass box over the rim, and the more famous voyage in The Potent Voyager, which was taken over by Rincewind and Twoflower. It is also possible that Carrot Ironfoundersson, Rincewind and Leonard da Quirm, when they traveled in the Kite in The Last Hero can by considered chelonauts, because they did go under the Disc.
    Chelonauts, according to the description, wear space costumes which look suspiciously like the ones Erich von Daniken thought he saw in prehistoric cave pictures.
    They spik a längwîdj wìth löts ðøv åccëntêd kåråcters, which gives it a distinctly Scandiwegian look.
    -https://wiki.lspace.org/mediawiki/Chelonaut
  • Olivier5
    6.2k
    scientists will poke and prod the see if there are indeed tulles, and even try to show that it's not turtles all the way down.Banno
    Okay but until they do, do you think "particles all the way down" is possible?
  • Banno
    23.4k
    ...until they do...Olivier5
    https://home.cern
  • Olivier5
    6.2k
    The good people in CERN haven't reached certainty quite yet.
  • Banno
    23.4k
    ...certainty...Olivier5

    There's your problem, right there.
  • Olivier5
    6.2k
    It's not my problem. I am fine with the idea that science will never reach certainty on much.
  • Enai De A Lukal
    211


    (that's good - but then a lack of certainty ceases to be a meaningful objection)
  • Olivier5
    6.2k
    It's a meaningful objection to the idea that CERN will find the answer to "could it be particles all the way down?" anytime soon, as Banno seemed to imply.
  • Enai De A Lukal
    211
    You can't have it both ways. Either its a realistic standard, such that its lack is a problem and therefore a meaningful objection... or its not. I think its very clearly not, since empirical/factual/scientific claims can never reach absolute certainty (even in principle), by their very nature, but I suppose YMMV.
  • tim wood
    8.7k
    Elsewhere in one of these threads one of us who knows his stuff makes clear it's a measurement problem. Can't measure but so fine, and what's finer we're not gonna know. If I find the post, I'l edit it in.

    Edit: @fdrake
    "It isn't an epistemological limit.

    In statistical modelling, there's a distinction between epistemic and aleatoric randomness. Epistemic randomness is like measurement error, aleatoric randomness is like perturbing a process by white noise. One property of epistemic randomness is that it must be arbitrarily reducible by sampling. Sample as much as you like, the uncertainty of that product is not going to go below the Gabor limit. That makes it aleatoric; IE, this uncertainty is a feature of signals that constrains possible measurements of them, rather than a feature of measurements of signals. There is no "sufficient knowledge" that could remove it (given that the principle is correct as a model)."
  • Olivier5
    6.2k

    Let's agree that a lack of certainty is not a problem.

    The experiments at CERN and other particle accelerators seem to show that the size of the pieces one can get (or observe) is a function of the amount of energy one can summon in ever larger accelerators.

    Conceptually, anything can be broken down into smaller pieces.

    So i guess it's perfectly possible that it's particles all the way down.
  • apokrisis
    6.8k
    The question is: could quarks be broken down in smaller pieces too? And those pieces of quarks, could they be further broken down, etc. etc. ad infinitum?

    Could there be no "bottom" to that stuff we call matter? Could it be "particles all the way down"?
    Olivier5

    Physics has shown that material particles only "break down" as far as their simplest possible symmetry states. So quarks exist as a mathematical limit on material symmetry breaking - the SU3 symmetry in their case. Electrons and neutrinos are the result of there being an even simpler accessible symmetry state - the U1 of electromagneticism (although the mechanism to get there is a little messy as you need this other things of the Higgs mechanism to break the intermediate step of the SU2 electroweak symmetry).

    So putting aside the technicalities, physics has flipped the whole issue. The mathematics of symmetry tell us what is the simplest possible ground state of material being. The nearest to a vanilla nothingness. A cosmic sea of U1 photons. The problem becomes more about how any complexity in the forms of higher level crud, such as quarks, or Higgs fields, manages to survive, and thus give us a materiality that needs describing in the fashion of turtles stacked high.

    At this point, the conversation has to shift from a classical metaphysics to a quantum one. And here the floor of reality becomes the very possibility of being able to break a symmetry with a question.

    You want to know the simplest formally complementary pair of facts about the nature of something that might exist - like its location AND its momentum. Well sorry. Those are the logical opposites as measurements, so that is certainly the ground floor when it comes to asking something concrete and definite. You can't logically get simpler, or more binary. But because they are opposites, not both can be measured with precision simultaneously. Exactness in one direction becomes complete uncertainty in the other.

    So again, we know in a mathematical way what constitutes the "smallest possible fragment of reality". A countable quantum degree of freedom.

    The mystery is more about how nature would begin the business of smashing its way down through a whole series of higher symmetry states - like SU10 or whatever else counts as the grand unified theory describing the Big Bang state - to arrive at its simplest achievable arrangement.

    That is the practical task before particle physics now. Recovering the story of when things were messy and complicated before they got reduced towards an idealised simplicity.

    It's a meaningful objection to the idea that CERN will find the answer to the OP anytime soonOlivier5

    CERN is all about recreating those earlier times when things were hot and messy. The everyday world around us has evolved to be about as primitive as it gets. Electrons can't decay because there is no simpler state they could achieve. But go back and higher symmetry states of matter can fragment in a vast variety of short-lived ways - short-lived as they too will want to reduce towards the simplest achievable state of being, like a U1 photon.
  • SophistiCat
    2.2k
    Conceptually, anything can be broken down into smaller pieces.Olivier5

    "Breaking things down into smaller pieces" is not a good way of describing fundamental physics research. Simple mereology works decently well with everyday objects and materials: if you know that something is made of wood, for example, then you know a lot of things about it, such as its hardness, heat capacity, conductivity, etc. So when we want to know more about a thing, we naturally tend to ask: "What is it made of?" If object O is made of A, B and C, and we know some properties of A, B and C, then we will add A, B and C properties together (perhaps accounting for some minimal interaction) and have O properties as a result.

    This doesn't work perfectly even with everyday objects, because isolated objects often behave very differently than when they are part of some whole. And when physics goes beyond everyday size and energy scales, the very notion of an "object" with a boundary and and a set of properties that are all its own begins to break down. Subatomic particles behave like "particles" only in a very limited sense. By the time you get to quarks, saying that something is "made of" quarks means very little.
  • Wayfarer
    20.7k
    It does well to remember the historic roots of atomism. The original atomists were addressing a particular philosophical problem - Why has everything in the world not yet decayed, and how can exactly some of the same materials, plants, and animals be recreated again and again? One solution to explain how indivisible properties can be conveyed in a way not easily visible to human senses, is to hypothesize the existence of atoms which are imperishable particles that never decay, but only recombine in an endless variety of forms.

    There was a famous Roman prose-poem, Lucretius' De Rerum Natura, which expressed this idea, and it's taught to this day. Lucretius underwent something of a revival in the French Enlightenment and was a favourite of the French materialists, such as D'Holbach ('all I see is bodies in motion'). And also Galilleo's science, and Descartes' philosophy, strongly suggested something like atomism, as 'atoms' could plausibly be interpreted as the ultimate bearers of Galileo's 'primary qualities' (hence, you could argue, the naming of atomic physics as 'quantum mechanics'.)

    That was where the appeal of atomism lay - the idea that these were the ultimate constituents of everything. And I think a lot of people, maybe even the majority, would still believe this to be the case.

    But it's worth bearing in mind that atomism was only one of many competing theories of matter. Plato and Aristotle didn't accept it, for different reasons, although whether one believes it or not, the atomic theory of matter has been extraordinarily fruitful from a scientific perspective.

    The problem becomes more about how any complexity in the forms of higher level crud, such as quarks, or Higgs fields, manages to survive.apokrisis

    CERN physicists recently declared that according to their best estimates, the Universe ought not to exist at all, as the matter and antimatter really should have cancelled each other out.

    The standard model predicts the Big Bang should have produced equal amounts of matter and antimatter – but that’s a combustive mixture that would have annihilated itself, leaving nothing behind to make galaxies or planets or people.

    To explain the mystery, physicists have been playing spot the difference between matter and antimatter – searching for some discrepancy that might explain why matter came to dominate.

    So far they’ve performed extremely precise measurements for all sort of properties: mass, electric charge and so on, but no difference has yet been found 1 .

    Don't know what conclusion to draw from that, other than, perhaps, there might be a problem with the theory.
  • apokrisis
    6.8k
    CERN physicists recently declared that according to their best estimates, the Universe ought not to exist at all, as the matter and antimatter really should have cancelled each other out.Wayfarer

    Yep. Almost all the matter and anti-matter - as mirror image states - did cancel each other away to leave the blazing sizzle of a cooling and expanding bath of photon radiation, the simplest possible form of being. But if you google CP violation, you will see that theory can predict a symmetry-breaking source of an underlying asymmetry that preserves a small fraction of matter. It has been observed with quarks. It just isn’t enough as yet. Other particles, like neutrinos, would have to contribute too.

    Early results have given physicists confidence skewed neutrinos can supply the missing amount of asymmetry. They just need more public money and a next generation detector to demonstrate that, natch. :wink:
  • Wayfarer
    20.7k
    Oh good. (Although had to read it twice, I thought you said 'stewed'.)

    //ps// although something tells me, if there's an even bigger accelerator, there will be even bigger questions more than answers.//
  • TheMadFool
    13.8k
    A small problem with the analogy.

    In the story of the infinite stack of turtles, it's as you say, turtles all the way down and the issue with this kind of infinite regress is that the same explanation repeats infinitely.

    In physics, the particles aren't the same particles: it's not protons/neutrons/electrons all the way down, different kinds of particles appear as we make our way from the small to the very small. In other words, it isn't turtles all the way down in physics.

    The error is in thinking the particles are the same particles. They're not. I wonder what CERN scientists would think if, for instance, they smash quarks and get quarks and nothing else. Would they think quarks are made of quarks and that these quarks are made of more quarks a al turtles all the way down OR would they hold a press conference and announce to the world they've finally discovered the fundamental particle of matter? :chin:
  • Asif
    241
    It's most definitely Interpretations all the way down.
    Though scientists and platonists have their own Interpretations of my Fact.
  • 3017amen
    3.1k
    The question is: could quarks be broken down in smaller pieces too? And those pieces of quarks, could they be further broken down, etc. etc. ad infinitum?Olivier5

    Sure! There also could exist multiple universes. In multiverse theory, there could be universes that use entirely different laws of physics. Cosmologically, whether it turtles or multiverse theories, perhaps the one common theme to all of them is that it they all require some form of belief, or leap of faith. Really not much different than scientific beliefs about causation.
  • EnPassant
    665
    - What does the second turtle rest on?Olivier5

    Something I wrote some time ago...

    One of the most intractable questions in philosophy is Why is there something rather than nothing? Very little progress has been made in answering this question. But we know there is something; 'I think therefore I am'. So, at least Descartes exists, or at the very least, 'there is thought' (Bertrand Russell). At any rate, we can begin with the assumption that there is something rather than nothing.
    The something that is, is existence. Existence is not a verb, it is a noun. It is the substance that is and always has been. Existence is God and is not contingent upon any previous state. Existence is not a property of anything, rather, existence has properties. To show that existence is not a property assume X has the property 'existence'. In this respect we consider X and existence to be distinct entities (otherwise X is equivalent to existence and there is nothing to prove). We now ask the question; Does X exist (as a distinct entity)? There are two answers;

    1. X exists.
    If this is the case existence, as a property of X, is superfluous since X exists anyhow. Therefore X is equivalent to existence.
    2. X does not exist.

    It is incoherent to say a non existent X has properties, let alone the property existence.
    This means that if existence is not a property, it is not contingent. That is, not dependent on any previous state. All other realities are properties of existence. The universe is a set of properties of existence. Properties of existence 'inherit' their existence. We can say 'This milk bottle exists'. By this we mean that the milk bottle is a property of existence and the substance of it is existence, because existence is the only substance that is.

    In principle we can deconstruct the bottle into glass crystals and we can deconstruct the crystals into molecules, atoms and so on until even the atoms are deconstructed into energy because energy is the substance of matter. It may even be possible to deconstruct energy into a deeper form of energy but this deconstruction cannot go on indefinitely; it cannot be 'turtles all the way down'. We must come to some ultimate substance that supports the properties 'atom', 'molecule', 'crystal' 'bottle'. This substance is that which is from the beginning, existence.
    Even though philosophy cannot say why existence is or what it is, there are a number of things we can say about it;

    1. Existence is.
    2. Existence has vast creative potential because it has emerged into a universe and everything in that universe.
    3. It has the potential to become life, because life is found in the universe.

    The way in which existence made manifest a physical and mental/spiritual universe is very special. It did not just spew out an amorphous blob of matter. It created the universe in a way that optimized the creative potential of matter. Matter, because of the precise way it is made, is capable of great creative transformations. It can become a planet, a crow, a city, an oak tree. If matter had been just a primitive blob it would not have the immense combinatorial possibilities it has. It is the precise balance within matter and energy that gives the universe its vast creative potential. This is the Fine Tuning Argument.
    Arguably, the highest point in the creative evolution of matter is the physical image of life and being; physical creatures. But the physical image is just that, an image. Life and being are of the mind which is non physical.

    Existence simply is. Being is concerned with life and consciousness; a milk bottle exists, a creature is alive and conscious. Life is plurality and unity. A single mind in isolation is hardly alive. Life is a discourse between minds, between self and not self. When existence becomes manifest as a myriad of minds it emerges into life and being. Life is the union of God and creation. Through creation existence/God emerge into being and God becomes the living God. Egoism is the severance of unity. The mind's consciousness turns inward and the bonds of life are broken. Egoism is counterfeit being and ultimately, spiritual death.

    ***

    It has been suggested that reality can be nothing more than a circular chain of properties or contingencies supporting each other in a never ending circle with no supporting substance. This is an absurdity as it tries to dispose of any real substance in reality.
    A property or contingency is perfectly identified with its supporting substance and cannot be divorced from it. Take for example a bronze sphere. Bronze is the supporting substance, and its sphericity is its property which is contingent upon the existence of the bronze. It is also perfectly identified with the bronze.

    Now, suppose you try to separate the bronze substance from its property, its contingent sphericity. You could try melting the bronze in the hope that you would end up with pure, abstract sphericity. But all that would happen is the bronze would turn into a molten puddle and the property, sphericity, would vanish. This shows how the property is perfectly identified with its substance; the property sphericity, in terms of substance, is the bronze.

    The idea that there can be a circle of mutually supporting contingencies or properties without substance is suspect.

    Let P1, P2,...Pn be a circle of properties. It is asserted that P1 is effectively the supporting 'substance' of P2 and P2 supports P3 and so on until we get to Pn which is the supporting substance of P1, completing the circle. So it goes round in a self supporting circle without any central supporting substance.
    But Pn is perfectly identified with Pn-1 in terms of 'substance' (although the substance in this case is not supposed to be actual, it is still assumed to play the part of the supporting substance). Pn-1 is perfectly identified with Pn-2 and so on until we get to-

    P2 is perfectly identified with P1.

    What this means is that any separation between P1 and P2 is purely conceptual and there is no separation in actuality. Likewise with P2 and P3 etc. In short, P1, P2...Pn all telescope into a single complex property. That is, there can only be primary, not secondary, properties in actuality. That there seems to be secondary properties is only an effect of the abstract conceptual model we make in our minds.

    Here is a simple illustration.

    Energy is the substance of atoms. P1 = a set of atoms.
    Molecules are made of atoms. P2 = a set of molecules.
    The cell is made of molecules. P3 = the cell.

    Energy is the substance of the whole system because it is the substance of Property 1, a set of atoms. Conceptually we have three levels of properties but working backwards we can see that the cell is a set of molecules. Molecules are a set of atoms. Atoms are energy.
    So P1, P2, and P3 can be collapsed into a single complex property, P3, the cell. In real terms P3 is a primary property of energy because the substance of the cell is energy, just as it is the substance of the atom. So, all the in between properties, as such, are just conceptual categories, not actualities. The error in the concept of a circle of a self supporting set of contingencies, without any supporting substance, is that there can be a property without any supporting substance. In other words, the universe is an abstraction, a property, of nothing. But even an abstraction needs a mind to conceive it and keep it in existence.
  • Olivier5
    6.2k
    Physics has shown that material particles only "break down" as far as their simplest possible symmetry states.apokrisis
    Until it proves otherwise, of course.

    So putting aside the technicalities, physics has flipped the whole issue. The mathematics of symmetry tell us what is the simplest possible ground state of material being. The nearest to a vanilla nothingness. A cosmic sea of U1 photons. The problem becomes more about how any complexity in the forms of higher level crud, such as quarks, or Higgs fields, manages to survive, and thus give us a materiality that needs describing in the fashion of turtles stacked high.apokrisis
    Okay, I get it. But what are the pathways and "steps" from a cosmic sea of U1 photons to, say, a quark, a proton, or an atom (or several)? Do we have all the "steps" plotted? Or does it look more like an infinite series of intermediary states between the U1 photon sea and an atom?
  • Olivier5
    6.2k
    Fair enough, there is a slight difference, but you get the point of the metaphor nevetheless.
  • Olivier5
    6.2k
    By the time you get to quarks, saying that something is "made of" quarks means very little.SophistiCat
    I'm not saying something is "made of quarks". Only that something can be broken down into quarks. There's a difference.
  • TheMadFool
    13.8k
    Fair enough, there is a slight difference, but you get the point of the metaphor nevetheless.Olivier5

    The story of the turtles ( ) is to expose the inadequacy of an explanation because it sets off an infinite regress consisting of the same explanation being repeated over and over again. As far as I can tell, the atomic theory of matter isn't like that. In the atomic theory there's an heirarchy of different particles each level forming the substratum of the next higher one and, most importantly, there's a sense of a limit where this will go - I suppose an ultimate final level of particulate matter is expected beyond which it doesn't make sense to ask what that particle is made up of?
  • Gnomon
    3.5k
    Could there be no "bottom" to that stuff we call matter? Could it be "particles all the way down"?Olivier5
    Most quantum physicists have reluctantly abandoned the ancient theory of Atomism : self-existent particles at the bottom --- the rest is all Void. Instead they have devised a Field Theory to describe fundamental Reality. But a "field" is essentially an empty space (void) where statistically possible Virtual particles could suddenly-and-without-warning become Actual particles. In that case, you could say that reality is Ghost particles all the way down. But I prefer a less spooky theory. :joke:

    Field Theory : "QFT treats particles as excited states (also called quanta) of their underlying fields, which are more fundamental than the particles."
    https://en.wikipedia.org/wiki/Quantum_field_theory
  • Olivier5
    6.2k
    most importantly, there's a sense of a limit where this will go - I suppose an ultimate final level of particulate matter is expected beyond which it doesn't make sense to ask what that particle is made up of?TheMadFool

    That's exactly the point of the thread: is there a limit to how fine we can "grind" matter?
  • TheMadFool
    13.8k
    That's exactly the point of the thread: is there a limit to how fine we can "grind" matter?Olivier5

    I think we need to draw a distinction between theoretical and practical limits. In the former case, any non-zero size is divisible but in the latter case we may not be able to actually subdivide particles of extremely small size.
  • Olivier5
    6.2k
    [in practice,] we may not be able to actually subdivide particles of extremely small size.TheMadFool
    Given our current technology we can only go so far, but technology can and does evolve.

    As others have pointed out, I’m talking about atomism, and how it served us well to assume that matter was « made of » some basic elements called « atoms ». The word means « unbreakable » and yet once we discovered what we now call “atoms », we also discovered they could be broken down in « sub-atomic particules » which themselves can be broken down (or up) into quarks... So the basic premisse of atomism is false: matter is not technically made of some basic elements. Instead, some forms of matter are stable in certain conditions, and break down in other conditions.

    Matter has no “bottom”, no “foundation”. It’s turtles all the way down.
  • TheMadFool
    13.8k
    Matter has no “bottom”, no “foundation”. It’s turtles all the way down.Olivier5

    Ok. There's a sense in which there's no end in sight to splitting particles - there always is a smaller particle to be cleaved off of a larger one - but, a partlcle can't have zero size i.e. there's a limiting boundary to particle size. Of course you could go Zeno on me and say there are an infinite number of possible fractional sizes for a particle and then, yes, it's turtles all the way down.
  • 3017amen
    3.1k


    TMF!

    Simple question (well maybe not so simple), could an interminable amount of regressive turtle power suggest infinity and/or eternity of time exists?
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