Technocrat

Sub-atomic particles: turtles all the way down?

N. Dan Smith
Tue Jul 29 12:48:00 -0700 2008
Physics.
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Scientists at the Large Hadron Collider are hoping to prove the existence of the Higgs boson, the particle which theoretically accounts for the phenomenon of mass.  It is one of a growing list of observed and predicted particles which are the constituent elements of atoms and forces.  Since the discovery of the atom, it seems these constituent particles have become all the more numerous, small, and hard to detect.  Will there be an end to this trend?  That is, will we find a base-level particle which is subject to no others?  Or will we continue finding smaller and smaller constituent particles - in other words, will it be "turtles all the way down?"

The film Men In Black, if I remember it correctly, ends with a gag wherein the entire universe we occupy ends up being a mere marble in a bag of marbles of some alien child.  It was a throw-away gag, but it was quite thought-provoking nonetheless.  Likewise, the matter of the immensity of space and the infinitesimal smallness of sub-atomic particles is as much a philosophical paradox as a scientific inquiry.  I suspect theoretical physics can provide an answer to my question.  That being said, the popular models of physics are being amended and replaced by new discoveries at an alarming rate of late.  At any rate, I am excited to see where the new discoveries take us.

Current theory

wowbagger
Tue Jul 29 13:11:20 -0700 2008
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Our current understanding of things would prevent "turtles all the way down".

The smallest a thing can be and have any hope of being measured is the Planck length. Putting it imprecisely, to resolve the position of a particle to smaller than this length, the energy would have to be so great that it would exceed the mass needed to form a black hole, so this is the fundamental quantum of length in the universe.

For a smaller particle to exist would require much of what we currently understand of how things work to be wrong. Not just "incomplete", like the difference between Newtonian gravity and Einsteinian gravity, but demonstrably dead wrong, like thinking the area of a circle is 2πR rather than πr2.

Of course, between what we have "seen" in the lab (quarks, gluons, leptons) and the Planck length there is a LOT of places for new "things" to be found, but the does seem to be an end to it.

Unless we find out that we *are* just a simulation in a virtual machine, and we find a way to "jailbreak" that VM....

Current theory
President4242
Tue Jul 29 18:04:40 -0700 2008
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If Planck Length can be measured, then what unit is it measured in?

And couldn't you have a fraction of that unit?

Don't confuse "unmeasurable in our model of the universe" with "unmeasurable forever".

Current theory
wowbagger
Tue Jul 29 18:48:54 -0700 2008
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You confuse "measuring" with "existing". Sure, I can talk about a half a Planck length, in the same way I can talk about the sound of one hand clapping. However, there is no way a particle can exist which is "half a Planck length" long (to be precise, which has a Compton wavelength of one half Planck length). In order to "be a half a Planck length" long, the particle would be so dense that it would a black hole with with an event horizon of one Planck length.

Current theory
President4242
Tue Jul 29 19:27:21 -0700 2008
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You confuse "measuring" with "existing". Sure, I can talk about a half a Planck length, in the same way I can talk about the sound of one hand clapping. However, there is no way a particle can exist which is "half a Planck length" long (to be precise, which has a Compton wavelength of one half Planck length). In order to "be a half a Planck length" long, the particle would be so dense that it would a black hole with with an event horizon of one Planck length.

And while I'll admit in our current MODEL of the universe, no such thing could exist, that doesn't mean that something like that doesn't exist outside of our model of the universe.

I'm always amazed at the amount of religious faith in science supposedly anti-religious science has.  There's a lot of assumption and presumption out there.

Would make a lot of seeable things

mrjk
Tue Jul 29 13:51:36 -0700 2008
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If the Standard Model is correct in the energies that we can see (and it has been confirmed many times in many ways) then it can't be turtles all the way down as you've described. For example there would effects from virtual particles that made up the electrons and quarks that would have an effect on things like the magnetic moment of an electron. Any charged particle would have these effects - and we would see them. We have calculated the electrons Magnetic Moment to 10+ decimal places and it matches measurements.

Quarks were found when electrons where smashed into protons ( and other hadrons) at high enough energy so that people could see that the proton and neutron had internal structure. But nothing has ever indicated that any lepton particle (electron, muon, tau) is composite, nor any quarks. Due to the nature of the strong force when you smash quarks in hadrons (protons, neutrons, pions, etc.) together hard enough, the energy simply produces more hadrons and hasn't shown any structure.

There could be something underneath current particles (e.g. superstrings) but it won't be anything like the subatomic particles we know. The rules will be totally different. Uncertainty relations preclude anything really really small, (by the energy issues in #1) so unless these rules are emergent (they could be) there won't be anything there. Plus many string models have a weird feature where small high (well let us say) energy modes are indistinguishable from larger low energy modes - they correspond to each other so would provide a lowest layer if these scenarios are accurate in any way.

Holographic Principle considerations would preclude lower levels also if it is correct since more levels would mean more information than could be expressed on the surface of a volume. Of course no one knows if the Holographic Principle holds.

Basically what I'm saying is this. If current physical models are true within their bounds then there can't be many lower layers. This is different than saying they just don't predict things in that area - it means if they are wrong then a new model has to contain all the correct predictions they give as well as an explanation of the new effects.

Of course we could all be simulations in a giant computer also. 

Sub-atomic particles: turtles all the way down?
James Tankersley Jr
Wed Jul 30 23:45:18 -0700 2008
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We are entering very unknown territory with the LHC.  I don't have a good clue as to how many "turtles" might exist, but I do know that the safety arguments are weak and shakey at best.

Professor Otto Rossler proposes that if the Large Hadron Collider creates a micro black hole it may likely destroy Earth.

A Rational and Moral and Spiritual Dilemma

 

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