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GU 2007 Quantum Illusions and Time 1 Quantum Illusions and Time Joan Vaccaro KK

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 2 Quantum States Photons (particles of light) polarisation of E (electric field): two orthogonal directions x y z E x y z E

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 3 arbitrary polarisation superpositions placement of “one thing on top of another” x y z E x y z E x y z E x y z E PBS 50% measurement

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 4 superposition of two positions x y z E verifying the superposition x y z E opaque absorber with 2 slits upper lower interference pattern photons pile up here one at a time but NOT here need many photons for verification d

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 5 Experiments photons 1802 Young electrons 1926 Davisson, Germer & Thomson atoms 1930 Estermann & Stern neutrons1945 Wollan & Shull bucky balls2002 Zeilinger virus? bacteria? flea? cat? people? Thomson Young Shull Zeilinger

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 6 …first a bit of history… 1920’s: treatment of radioactive decay paths Pa( ) of single particle cloud chamber radioactive atom possible tracks Tr( ) & but only one track per particle is seen Many Worlds Tr( 1 ), Pa( 1 )Tr( 2 ), Pa( 2 )Tr( 3 ), Pa( 3 )Tr( 4 ), Pa( 4 )

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 7 Copenhagen Interpretation: 1927: Bohr and Heisenberg in Copenhagen when experimenter looks at cloud chamber its state collapses see only one track Tr( 3 ), Pa( 3 )Tr( 4 ), Pa( 4 )Tr( 1 ), Pa( 1 )Tr( 2 ), Pa( 2 )

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 8 radioactive atom + Geiger detector :00 Schrödinger’s Cat

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 9 radioactive atom + Geiger detector hammer trips and breaks vial of poison cat dies Schrödinger’s Cat :30

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 10 Schrödinger’s Cat Partial decay leads to superposition state radioactive atom + Geiger detector hammer trips and breaks vial of poison :15 cat dies until experimenter looks inside box and state collapses hi kittyoh no… OR 50% chance

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 11 hi kittyoh no… OR 50% chance I don’t like it and I’m sorry I ever had anything to do with it. Schrödinger collapse is not described by any dynamical process (with forces, potentials etc.)

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 12 Everett 1957 (50 th anniversary year) applying quantum mechanics to universe (cosmology) no external observers (experimenters) to collapse state We need new toy example don’t know how to treat “no life process” (dead) and “life process” (alive) as physical states

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 13 The cat that may (or may not) be fed :00 3

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 14 The cat that may (or may not) be fed :30 3

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 15 The cat that may (or may not) be fed :15 Why don’t we see this superposition?

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 16 This is what happens when we look… here kitty-kitty…

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 17 This is what happens when we look… there you are you’re so hungry you’ve over eaten …so how do we see superpositions

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 18 The dropped cat experiment (with catchers) - how to “see” a superposition interference probability

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 19 The dropped cat experiment (with catchers) - how to “see” a superposition interference probability

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 20 The dropped cat experiment (with catchers) - how to “see” a superposition probability d xx L interference Parameters d = 0.1m x = 1m m = 10 kg L = m t = y

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 21 we never even try to do this kind of experiment - need control (& disentangle atom… from cat etc.) - but, importantly, need to repeat it many times to build up interference pattern separate “worlds” evolve… here’s food you’ve fat! the poor but happy worldthe rich but sad world the perception of “one single world” is an illusion $$$$

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 22 Many Times Pegg, J.Phys. A 24, 3031 (1991). David Pegg’s quantum theory of time canonical approach to quantising gravity Wheeler-deWitt - equation: - universe is in a stationary state - no motion – frozen dynamics - energy is well known (zero) Heisenberg uncertainty principle if you know position X well, momentum P is uncertain “ “ energy E “ time T “ “ time in the universe must be uncertain XP prob. XX PP

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 23 use new set of axes – each axis represents a different time axes chosen to make projections all equal state of the universe 11 22 33 44 55 11 22 33 History vector – totality of reality – state at all times

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 24 divide universe into 2 parts: Clock + Rest clock must have equally spaced energy levels C R orthogonal clock states find interval where Clock and Rest are separate and non-interacting rewrite interval in terms of orthogonal clock states 11 MM M+1 PP

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 25 C R1R1 R2R2 R3R3 RPRP the dynamics of Rest can be written in terms of the time parameter t defined by Clock: t = Schrödinger’s equation for dynamics MM M+1 PP R R n+1 RnRn tt RnRn RnRn tt RnRn

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 26 C R R1R1 R2R2 R3R3 RPRP we live at these different times the perception of “one present” is an illusion this illusion is on par with the single world illusion

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 27 Puzzle: how does our perception of travelling in time arise? R1R1 R2R2 R3R3 RPRP R m-1 RmRm R m+1 R these states of Rest are non-orthogonal so can’t be sure which one we are in this gives a connection between different states of Rest but the connection is the same in both directions!

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 28 space time gamma ray photons electron e anti- electron e + electron e Puzzle: why do we travel in one direction in time? anti-particles are the time reversed versions of particles all anti-particle and particle pairs are time symmetric except for Kaons (K mesons)

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 29 (more likely) equal number of K 0 and are found to yield different numbers of e + and e violation of CP & T symmetry (CERN 1998) K0K0 matter K0K0 e+e+ K0K0 + ee antimatter matter antimatter positron pion neutrino electron pion antineutrino Neutral kaons K 0 have a lifetime of less than 10 6 s. Decay paths: K 0 e + + + e + + + R1R1 R2R2 R3R3 RPRP K0K0 K0K0 long lifetime time asymmetric K0K0 short lifetime t

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 30 R1R1 R2R2 R3R3 RPRP R m-1 RmRm R m+1 only unsure of which state in the “future” we are in K0K0 t K0K0 long lifetime short lifetime Kaons appear to be responsible for us travelling through time!!!

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GU 2007 Quantum Illusions and Time Contents Quantum States Many Worlds Many Times 31 Many worlds: we exist in many worlds but have the illusion (and pleasures) of only one - but somewhere we are having a really good time Many times: we exist at many times but have the illusion of only one present which marches steadily toward to our demise! - but consoled by knowing we still exist at earlier times Free will: even our perception of free will is an illusion – we cant change the future because we already exist there (hopefully) - but we can enjoy the illusion Conclusion RIP

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