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Quantum Mechanics, Reality, & You
 

Quantum Mechanics, Reality, & You

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Weird, true, & out of control

Weird, true, & out of control

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  • Request by Miriam: what is your next talk?\nA problem?\nNext day shipped off a wonderful title (you can see it here)\nNew problem. OK, we have the title, now what?\nAnswer here.\n\nStart with phenomenology\n
  • Collapse into the selected one\n\n\n
  • Cordelia Chase put it, behold the weird\n
  • And entanglement\n\nDefine wave function. For now, a mathematical object that tells us how a particle moves. Later, much discussion.\n
  • And quanta\n\nClassical physics has limits as well, but in quantum mechanics, like a glob of mercury\n\nEssential for atoms, no uncertainty no atoms\n\n10-8 seconds classically to get down to center\n
  • Copenhagen interpretation clearest in the Stern-Gerlach experiment: the poster child for the Copenhagen interpretation\n\nhttp://www.pci.uzh.ch/static/documents/Stern-Gerlach-Experiment.jpg\n
  • This is crazy\n\nKübler-Ross five stages of grieving:\nDenial\nAnger - objections in our case\nBargaining\nResignation - shut up & calculate\nAcceptance\n
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  • “there are only two avenues through which experimentation can proceed to obtain information about [1]: observation of infants where we may be able to sense the progress of the awakening of consciousness, and by discovering phenomena postulated by [2], in which the consciousness modifies the usual laws of physics.\n\nVery scientific. Hard to get naive babies however\n\nhttp://jwsokol.com/scc/wp-content/uploads/2011/07/holden-andrew-portrait-of-a-surprised-baby.jpg\n\n\n\n
  • Good example of scientific method\n\nEliminates special role since it uses a potential that does all the dirty work\n\nNon-linear, stochastic, & depends on surround actually sounds a lot like decoherence, below.\n\nA bit of a long shot.\n\nMore interesting for the principle. Did kick off a lot of variations! Dickson wrote a book on the whole class of such theories.\n\nNever seen\n\n\n
  • Tiny mirror should lose coherence from gravity, if weight of grain of dust.\n\nFirst - hard part - calibrate your system. Normal Mach-Zehnder interferometer would see effects of phase. Instead, set up two cavities so that the photon oscillates for a long period of time, perhaps a second, between the two sides, thus never getting to the detector.\n\nIf the mirror is decohered by gravity, then the photon will be detected.\n\nShows up in Verlinde’s entropic gravity\n
  • Get cat, turn into picture\n\nhttp://scrappinoutloud.blogspot.com/2009/08/black-cat-svg-just-in-time-for.html\n\nhttp://www.halloweenclipart.com/halloween_clipart_images/angry_scared_black_cat_hissing_with_its_back_arched_0071-0810-2316-0831.html\n\nhttp://2e6vizille.wikispaces.com/file/view/1197122845337673748paulshannon_Old_Timey_Radio.svg.med.png/112448403/1197122845337673748paulshannon_Old_Timey_Radio.svg.med.png\n
  • Picture appropriate to hidden variables, tunneling under the castle\n\nQuantum mechanical statistics a problem for hidden variables\n\n
  • Bohr’s response; you are only allowed to speak of what you can measure. Feynman: you are only required to speak of what you can measure.\n\n
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  • If you know that when sock A is red, sock B is green 99% of the time, and when sock B is green sock C is blue 99% of the time, then when sock A is red, sock C has to be blue 98% of the time.\n\nInformation distance is a more format, precise way to characterize this.\n
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  • Nice pictures\n\nSee also consistent histories\n
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  • Benefits:\nNo collapse\nObserver included\n
  • Experimental tests:\n\nQuantum suicide: control the gun via a radioactive decay. But keep the decay from happening using the quantum zeno effect. Now the decay doesn’t happen so the gun doesn’t go off.\n\nAlternative, have a plethora of observers, in MWI in some versions, \n
  • Quantum suicide\n\nRivers, neurons, branches of timelines\n\nIf the statistics depend on the \n
  • Pencils & thinking, einstein; sometimes the pencil thinks for me!\n\nModel testing\n\nDefeatist/resignation\n\nAnd keeps you from pushing the boundaries\n
  • Hidden variables\n\nQuantum mechanics wave functions complete, or so it seems. Statistics alone would indicate this. \n\nhttp://www.forizslaszlo.com/tudomany/wheeler_law_without_law.html \n
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  • Conan quoting Nietzsche, in an unexpected burst of erudition. And time travel. Also, basis of a currently popular song, Stronger.\n\n\n
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  • Last week in nature physics\n\nPrepare two quantum states so cleverly that they will cancel when they intersect. Canceling not something that comes naturally to hidden variable theories. The precise nature of the cancellations lets us infer the original quantum states. Therefore they are real.\n
  • Venus & the half shell\n\nBack to the crime scene\n\nHow to get some numbers out\n\nhttp://www.armee.gc.ca/35rgc/images/sape.jpg\n\n
  • A set of harmonic oscillators in a heat bath\n\n
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  • Entropic Gravity - & the collapse?\nOrigin of the universe\nWhispering gallery of the multiverse\n
  • Quantum mechanics interesting & important, rich source of metaphors. Our successes in understanding it very encouraging, ability to transcend own limitations, even if sometimes we have to let the pencil do the thinking!\n\nBut the stuff we care about exists at a level of abstraction well above that of the quantum. Problems of free will & determinism not a function of classical/quantum: both are deterministic in their own way, but both are incalculable.\n\n\n

Quantum Mechanics, Reality, & You Quantum Mechanics, Reality, & You Presentation Transcript

  • Quantum mechanics, Reality, & You John Ashmead
  • QM-RAY •“Behold the weird” •The collapse of the collapse of the wave function •Existential quantum mechanicsQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • “Behold the weird” •Double slit experiment •Uncertainty principle •Checkpoint Copenhagen •Schrödinger’s CatQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Double slitQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Uncertainty principleQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Copenhagen interpretationQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Schrödingers Cat One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following diabolical device (which must be secured against direct interference by the cat)…QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • The collapse of the collapse of the wave function •Collapse real •Hidden variables •Multiverse •Shut-up-and-calculate •“That which does not destroy you…”QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Objective collapse •Wigner’s Calibrated Panel of Infants •The all collapse all the time channel •Penrose finds decoherence in a grain of sand •The case of the highly charged catQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Wigner’s Panel of infants 1. Perception counts as consciousness. 2. Consciousness induces deviations from laws of physics.QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Unified dynamics for microscopic & macroscopic systems (1986) - Ghirardi, Rimini, Weber •Eliminate special role of observer •Posit an interaction which is non-linear, stochastic, & depends on surround •Get a GRW collapse perhaps every 100 million yearsQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • The road to reality • Tiny mirror in two states at once • With gravity involved, this costs energy • Forcing it to pick one of the two states. • And causing the beam to lose coherenceQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Highly charged cat Charge up your Let its wave function diffuse cat Observe your cat Accelerated charges radiate Tune your radioQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Hidden variables •Statistic interpretation •Einstein- Podolsky- Rosen: elements of reality •Bell’s theorem •Bohmian mechanicsQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Einstein podolsky rosen You can’t know both x-spin & z-spin at the same time, & yet you can.QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Bell’s Theorem Measure along x, or along z, or along their bisector, but only one measurement (of each spin) per round One poke per measurementQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Information Distance Information distance Information distance from A to B is the obeys the triangle uncertainty left in B inequality when A is known. d ( A,C ) ≤ d ( A, B ) + d ( B,C ) B d ( A, B ) d ( B,C ) A C d ( A,C )QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Information ZigZag 1.0 θ left θ right 0.8 0° 0.6 0.4 .020 .0 0.2 10° 50 100 150 .020 .064 ( ) ( ) d (θ ) = − lg cos 2 (θ 2 ) cos 2 (θ 2 ) − lg sin 2 (θ 2 ) sin 2 (θ 2 ) p ≡ cos 2 (θ 2 ) 20° θ = 10° → p (θ ) ≈ 99%, d ≈ .020 θ = 20° → p (θ ) ≈ 96%, d ≈ .064 .064 > .020 + .020 Violates triangle inequality!!!QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • The right way to get it wrong Nick Herbert’s Faster-Than- Light Telegraph June 2012, Scientific AmericanQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Bohmian Mechanics • Well-defined particles • Guided by a pilot wave that obeys Schrödinger equation • Problems with many particles, high energies • Popular, if weirdQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Multiverse •Many worlds, many minds, many words •Quantum suicide/a plethora of observers •Splitting headachesQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Universes Fork Observers fork tooQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Experimental tests • Quantum suicide • Count of observers (many minds) has implications • Leakage between universesQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Splitting headaches • Why this set of alternatives & not that? • When does split happen? • How does split happen? • That’s rather a lot of "I am glad of all details," universes, isn’t it? remarked my friend, "whether they seem to • What counts as an observer? you to be relevant or not." • Can different universes chat?QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Shut-up-&-calculate •Arguably most popular •Let the pencil do the thinking. Or Mathematica. •Pencils a bit short on imagination sometimes.QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • “What we call `reality’ consists of an elaborate papier-maché construction of imagination and theory fitted in between a few iron posts of observation.” - John A. WheelerQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Many Interpretations • Deterministic • Wave function real • Hidden variables • Collapse real • Observer part of interpretation • Local/non-local • Time symmetricQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • “That which does not destroy you makes you strong” • 27+ rival interpretations •Critics such as Wigner, Bell, Einstein, … •300+ foundational experiments (Auletta)QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Existential Quantum mechanics •The wave function needs no interpretation •Decoherence •Radical conservatism •At the edge of the known •A game of chessQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Pusey, Barrett, & Rudolph •The quantum state of a system can be inferred uniquely from the physical state •Provided the predictions of quantum mechanics are correct. (They are.)QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Decoherence How does classical definiteness emerge from the quantum sea?QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Decoherence still cohering •Toy cases •Bound states •Quantum Zeno effect •Stochastic resonanceQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • Radical conservatism Be conservative by sticking to well- •Cat states established physical •Long range entanglement principles, but probe them by exposing •Phonons their most radical conclusions. •Bose-Einstein condensates - J. A. Wheeler •Majorana fermionsQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • At the edge of the known •Entropic gravity •Origin of the universe •Dark flow •Whispering gallery of the multiverseQM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959
  • A game of chess •Multiple levels of analysis •Appropriate mathematics http://research.cs.queensu.ca/Parallel/ QuantumChess/QuantumChess.html •Your move!QM, Reality, & You - John Ashmead - May 27th, 2012 - Balticon http://timeandquantummechanics.com/?p=959