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“What is the meaning of it, Watson? … It must tend to some end, or else our universe is ruled by chance, which is unthinkable. But what end?” “There is the great standing perennial problem to which human reason is as far from an answer as ever.”. Sherlock Holmes, 1892. - PowerPoint PPT Presentation
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“What is the meaning of it, Watson? … It must tend to some end, or else our universe is ruled by chance, which is unthinkable. But what end?”
“There is the great standing perennial problem to which human reason is as far from an answer as ever.”
Sherlock Holmes, 1892
Peek-A-Boo, Peek-A-Boo, Quantum Slits Quantum Slits
and Rabbit Holesand Rabbit Holes
What modern physics What modern physics does (and does not) does (and does not)
say about reality.say about reality.
Everything you always wanted Everything you always wanted to know about…to know about…
The nature of science, quantum mechanics, God, peek-a-boo, free will, cupcakes, ice cream, half-dead cats, and Hamlet…
…will not be answeredduring this talk.
I will try to mention all of those things.
Apologies for formality:Apologies for formality:
According to Dr. Gerry Wheeler, former According to Dr. Gerry Wheeler, former Executive Director of the National Science Executive Director of the National Science Teachers Association…Teachers Association…
““Power corrupts,Power corrupts,
and PowerPoint corrupts absolutely.”and PowerPoint corrupts absolutely.”
Also according to Dr. Wheeler:Also according to Dr. Wheeler:
There is a new “complementarity principle”There is a new “complementarity principle”of science teaching:of science teaching:
Can you handle the truth?Can you handle the truth?
When asked (by People Magazine) to When asked (by People Magazine) to explain Quantum Electrodynamics, explain Quantum Electrodynamics, Richard Feynman replied:Richard Feynman replied:
““If I could explain it to the average personIf I could explain it to the average personit wouldn’t be worth the Nobel Prize.”it wouldn’t be worth the Nobel Prize.”
The Truth!The Truth!
Quantum Quantum Electrodynamics:Electrodynamics:
Why do scientists fear “Clarity”?Why do scientists fear “Clarity”?
Everything should be made as simple as possible,
but not simpler.
Where can we find clarity?Where can we find clarity?
Scientific knowledge is finite.
Scientific inquiry leads to more questions.
Certainty is more comfortable.
Religion can provide that.
Science and ReligionScience and Religion
Three popular works on science and Three popular works on science and religion follow.religion follow.
Ideas expressed in each of them may Ideas expressed in each of them may be right or wrong.be right or wrong.
Some ideas are outside the realm of Some ideas are outside the realm of science.science.
The distinction between science and The distinction between science and religion may be valuable.religion may be valuable.
Science and Religion IScience and Religion I
Science = PantheismScience = Pantheism
““Science says”Science says”We create the universe We create the universe just by thinking about itjust by thinking about it
A belief held by A belief held by Freeman Dyson, etc.Freeman Dyson, etc.
2004
Science and Religion IIScience and Religion II
Rationality = AtheismRationality = Atheism
““Science says” Science says” The universe is ruled The universe is ruled by chance, not Godby chance, not God
A belief held by A belief held by Richard Feynman, etc.Richard Feynman, etc.
2007
Science and Religion IIIScience and Religion IIIPhysics = TheismPhysics = Theism
(with a capital “T”)(with a capital “T”)
““Science says”Science says”There is an active There is an active conscious Godconscious God
A belief held byA belief held byStephen Barr,Stephen Barr,Quantum Field TheoristQuantum Field Theorist
2003
Is anything wrong with this?Is anything wrong with this?
Any of these Any of these religiousreligious ideas ideascould be correct.could be correct.
Confusing science and religion Confusing science and religion potentially weakens both:potentially weakens both:Science relies on skepticism.Science relies on skepticism.Religion depends on faith.Religion depends on faith.
Map of this talkMap of this talk
Pictures and conversations:Pictures and conversations:The nature of scienceThe nature of science
Inside the Rabbit Hole:Inside the Rabbit Hole:Quantum physicsQuantum physics
Through the Looking Glass:Through the Looking Glass:Quantum physics and realityQuantum physics and reality
Seeking a way out of the wood:Seeking a way out of the wood:Science and religionScience and religion
Pictures and conversations:Pictures and conversations:
SCIENCE
The nature The nature of scienceof science
"What is the use of a book," thought Alice,
"without pictures or conversations?”
The nature of scienceThe nature of science
Observation
Mental Model
Idea
ExperimentPrediction
The nature of scienceThe nature of science
Scientists make mental models:Scientists make mental models:“Pictures” of the real world.“Pictures” of the real world.
Then they test the models:Then they test the models:“Conversations” with nature.“Conversations” with nature.
What isn’t science?What isn’t science?
If it isn’t accessible toIf it isn’t accessible toObservationObservation
PredictionPrediction
ExperimentExperiment
It isn’t science.It isn’t science.
(That doesn’t mean it’s wrong.)(That doesn’t mean it’s wrong.)
Is this science?Is this science?
I drop a ball.I drop a ball.
I notice that it falls.I notice that it falls.
I hypothesize that it fell because I’m I hypothesize that it fell because I’m standing on a large massive object (the standing on a large massive object (the Earth) which pulled on the ball. Earth) which pulled on the ball.
HINT: Could we devise an experimentHINT: Could we devise an experimentto test the hypothesis?to test the hypothesis?
Is this science?Is this science?
I drop a ball.I drop a ball.
I notice that it falls.I notice that it falls.
I hypothesize that it fell because a divine I hypothesize that it fell because a divine being wanted it to fall. being wanted it to fall.
No experiment could test this hypothesisNo experiment could test this hypothesisso it isn’t science. so it isn’t science. Science can’t sayScience can’t say
anythinganything about this hypothesis. about this hypothesis.
Quantum Physics:Quantum Physics:
Inside the Inside the
Rabbit HoleRabbit Hole
Artwork by Jessie Wilcox-Smith
Quantum Physics: A HistoryQuantum Physics: A History
Max Planck (1901)Max Planck (1901)Albert Einstein (1905)Albert Einstein (1905)Niels Bohr (1913)Niels Bohr (1913)Louis de Broglie (1924)Louis de Broglie (1924)Schrodinger, Heisenberg, Dirac (1926)Schrodinger, Heisenberg, Dirac (1926)Feynman, Schwinger, Tomonaga (1940)Feynman, Schwinger, Tomonaga (1940) … … and so on…and so on…
Quantum Theory BeginsQuantum Theory Begins
Max Planck (1901)Max Planck (1901)
Light has some of the properties of
particles.
And I should care because…why?
Waves and ParticlesWaves and Particles
One particle…One particle…
… … plus another particle …plus another particle …
… … equals two particles.equals two particles.
One wave plus another wave equals ???One wave plus another wave equals ???
Waves and ParticlesWaves and Particles
Waves or particles?Waves or particles?
Isaac Newton (1675)Isaac Newton (1675)
Light is composedof particles.
Waves or particles?Waves or particles?
Christian Huygens (1678)Christian Huygens (1678)
Light is composedof waves.
Waves or particles?Waves or particles?
Thomas Young (1799)Thomas Young (1799)
Huygens was right.Light is a wave.
Young’s Double Slit ExperimentYoung’s Double Slit Experiment
Young’s Double Slit ExperimentYoung’s Double Slit Experiment
Computer simulations by U of Colorado Computer simulations by U of Colorado PhET: PhET: http://phet.colorado.edu
Demonstration with sound:Demonstration with sound:http://phet.colorado.edu/new/simulations/sims.php?sim=Sound
Demonstration with light, etc.:Demonstration with light, etc.:http://phet.colorado.edu/new/simulations/sims.php?sim=Quantum_Wave_Interference
Waves or particles?Waves or particles?
J. C. Maxwell (1861)J. C. Maxwell (1861)
(So light is a wave.)
Quantum Theory BeginsQuantum Theory Begins
Max Planck (1901)Max Planck (1901)
Light has some of the properties of
particles.
But if Young was right, that means light has properties of particles AND properties of waves.
Albert Einstein (1905)Albert Einstein (1905)
Yep.
Waves or particles?Waves or particles?
Louis de Broglie (1924)Louis de Broglie (1924)
Atoms and electrons have some properties
of waves.
Map of the atomMap of the atom
Waves or particles?Waves or particles?
Louis de Broglie (1924)Louis de Broglie (1924)
Atoms and electrons have some properties
of waves.
Waves or particles?Waves or particles?
Waves (such as light)
are PARTICLES.
Particles (such as atoms)
are WAVES.PARTICLES! WAVES!Less Filling! Tastes Great!
Waves or particles?Waves or particles?
STOP!STOP!
Niels Bohr (1925)Niels Bohr (1925)
They’re particles…
and they’re waves.
Yin… and yang..
Wave + Particle = “Quantum”
But what does a “wave-particle” or “quantum” do?
Back to the University of Colorado:http://phet.colorado.edu/new/simulations/sims.php?sim=Quantum_Wave_Interference
Wave + Particle = “Quantum”
If you don’t know which slit a particle went through…
…it will act like a wave that went through both…
… and interfere with itself.
Wave + Particle = “Quantum”
Alternate experiment:• Build a bunch of “boxes”• Trap the particle in one of them• …without knowing which one.• Release the particle• It should interfere with
itself like a bunch of waves that came from each box.
Wave + Particle = “Quantum”
Actual photos of atoms released from Ramsey traps.
Wave + Particle = “Quantum”
Photos of atoms interfering after release from a two dimensional grid of slits.
Wave + Particle = “Quantum”
A porphyrin ring: a large quantum “particle”.
Wave + Particle = “Quantum”
Porphyrin rings fired at detectorthrough arrays of slits.
Wave + Particle = “Quantum”
Interference pattern appears as changes in the number of rings detected.
Quanta and Quantum MechanicsQuanta and Quantum Mechanics
For many experiments, Quantum Mechanics For many experiments, Quantum Mechanics only only predicts the predicts the probabilityprobability of any outcome.of any outcome.
What What kindkind of probability is this? of probability is this?
Two gamesTwo games
1.1. A deck of cards (no jokers) has been shuffled. A deck of cards (no jokers) has been shuffled. Is the top card red (Is the top card red (or or ) or black () or black ( or or ) ?) ?
2.2. A single die will be thrown. Will the outcome A single die will be thrown. Will the outcome be odd or even?be odd or even?
Two gamesTwo games1.1. A deck of cards has been shuffled…A deck of cards has been shuffled…
2.2. A single die will be thrown…A single die will be thrown…
Game #1: Outcome is predetermined but unknown. Game #1: Outcome is predetermined but unknown.
Game #2: Outcome is undetermined (unknowable?).Game #2: Outcome is undetermined (unknowable?).
InterpretationsInterpretations of Q. Mechanics of Q. Mechanics
Copenhagen Interpretation:Cards are not secretly shuffled in advance.
There is no pre-determination. Probability is all there is.
No dice.
Hidden Variables Interpretation:Quantum Mechanics is not complete. There is more information, but we don’t know it.
God does not play games with dice.
Stop telling God what to do.
““Interpretations”Interpretations”
We use the word “interpretation” for ideas We use the word “interpretation” for ideas that are beyond the reach of experiments.that are beyond the reach of experiments.
Is there a difference between a religion Is there a difference between a religion and an interpretation? and an interpretation?
There are other interpretations:There are other interpretations: Many Worlds (Hugh Everett)Many Worlds (Hugh Everett) ““Time waves” or Transactions (Emil Wolf) Time waves” or Transactions (Emil Wolf)
Not always.Not always.
Mysteries of CopenhagenMysteries of Copenhagen
“Observation”, “measurement”, or “experiment” occurs.
Before observation, only “mixtures of probability” exist. Physical properties (to be measured) are undefined.
After observation, measured physical properties are defined.
“Observer”
Mysteries of CopenhagenMysteries of Copenhagen
How can a coin be a “superposition” of How can a coin be a “superposition” of heads heads andand tails? tails?
How does it “snap” into one state or the How does it “snap” into one state or the other upon observation?other upon observation?
So maybe it’s all wrong?So maybe it’s all wrong?
1940:1940:Quantum MechanicsQuantum Mechanics+ Special Relativity+ Special Relativity
= Quantum Field Theory= Quantum Field Theory
Quantum Field TheoryQuantum Field Theory
Remember me?Remember me?
Quantum ElectrodynamicsQuantum Electrodynamics
Quantum Field TheoryQuantum Field Theory
Quantum Electrodynamics:Quantum Electrodynamics:The magnetic moment of an electron is…The magnetic moment of an electron is…
Theory: Theory: 1.00115965214 1.00115965214 0.00000000004 0.00000000004
Experiment:Experiment: 1.001159652181 1.001159652181 0.000000000001 0.000000000001
Quantum ElectrodynamicsQuantum ElectrodynamicsThe magnetic moment of an electron is…The magnetic moment of an electron is…
Theory: Theory: 1.0011596521 1.0011596521
Experiment:Experiment: 1.0011596521 1.0011596521
Quantum Field TheoryQuantum Field Theory
Theory: 1.00115965214 Theory: 1.00115965214 0.00000000004 0.00000000004
How accurate is that?How accurate is that?
So maybe it’s all wrong?So maybe it’s all wrong?
Wave function “collapse” and reformation has been observed.
Through the looking glass:Through the looking glass:
Quantum Physics and Reality
Through the looking glass:Through the looking glass:
1.1. Peek-A-BooPeek-A-Boo
2.2. FingerprintsFingerprints
3.3. TravelTravel
4.4. RestaurantsRestaurants
(they might all be wrong)
Four principles of “reality” that we believe in:
Principle #1: Peek-A-BooPrinciple #1: Peek-A-Boo
Peek-A-Boo LogicPeek-A-Boo Logic
Object Permanence: Object Permanence:
““Mommy comes back”Mommy comes back”
Things that disappear Things that disappear from sight are still there.from sight are still there.
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Watch this Watch this experiment.experiment.
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Watch this Watch this experiment.experiment.
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Watch again.Watch again.
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Watch again.Watch again.
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
What happened?What happened?
Was it this?Was it this?
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
What happened?What happened?
Was it this?Was it this?
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Or was it this??Or was it this??
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Or was it this??Or was it this??
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Or was it this???Or was it this???
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
Or was it this???Or was it this???
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
The only wayThe only wayfor sciencefor scienceto answer theto answer thequestion is toquestion is torepeat therepeat theexperiment…experiment…
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
The only wayThe only wayfor sciencefor scienceto answer theto answer thequestion is toquestion is torepeat therepeat theexperiment…experiment…
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
……and repeatand repeatit again…it again…
The Peek-A-Boo PrincipleThe Peek-A-Boo Principle
……and again.and again.
Peek-A-Boo LogicPeek-A-Boo Logic
Scientific inquiry does not allow us to Scientific inquiry does not allow us to assumeassume the nature of phenomena that the nature of phenomena that
are not observed.are not observed.
Example…Example…
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
Tunneling: Somehow quanta get from one Tunneling: Somehow quanta get from one place to another when it is impossible for place to another when it is impossible for them to be in between.them to be in between.
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
Tunneling: Somehow quanta get from one Tunneling: Somehow quanta get from one place to another when it is impossible for place to another when it is impossible for them to be in between.them to be in between.
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
We never see the particle We never see the particle insideinside the place the place where it is impossible to be (the barrier).where it is impossible to be (the barrier).
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
We never see the particle We never see the particle insideinside the place the place where it is impossible to be (the barrier).where it is impossible to be (the barrier).
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
We might want to get a snapshot like this…We might want to get a snapshot like this…
… … but nature doesn’tbut nature doesn’t
care what we want.care what we want.
Peek-A-Boo and PhysicsPeek-A-Boo and Physics
Artist’s conception of tunneling:Artist’s conception of tunneling:
Peek-A-Boo LogicPeek-A-Boo Logic
Scientific inquiry does not allow us to Scientific inquiry does not allow us to assumeassume the nature of phenomena that the nature of phenomena that
are not observed.are not observed.
“ “Hidden variables” supposes these Hidden variables” supposes these phenomena are there but does not phenomena are there but does not
suggest what they are.suggest what they are.
“ “Copenhagen” and Peek-A-BooCopenhagen” and Peek-A-Boohave a more complicated relationship.have a more complicated relationship.
Peek-A-Boo and CopenhagenPeek-A-Boo and Copenhagen
A radioactive atom “decays” when it emits radiation.
The leftover atom is physically changed.
Peek-A-Boo and CopenhagenPeek-A-Boo and Copenhagen
Erwin Schrödinger (1935)
What if we put the atom in a box without an observer?
When it is in a box, I can’t tell whether it has decayed or not.
It hasn’t been observed, so “Copenhagen” says it exists
in a superposition state.
A superposition of “decayed” and
“un-decayed” states.
Peek-A-Boo and CopenhagenPeek-A-Boo and Copenhagen
Erwin Schrödinger (1935)
Now add one cat.Problem: If the cat hasn’t
been observed, then isn’t the cat also in a superposition
state of dead and alive?
How can a cat be half dead?
The Afshar ExperimentThe Afshar Experiment
Shahriar Afshar (2004)Shahriar Afshar (2004)
Peek-A-BooPeek-A-Boowithwith
photonsphotons
The Afshar ExperimentThe Afshar Experiment
Lens focuses light.Lens focuses light.
One detector is aligned with each slit.One detector is aligned with each slit.
Double slits with lens and mirrors:Double slits with lens and mirrors:
The Afshar ExperimentThe Afshar Experiment
Photons show up atPhotons show up atdetectors anyway.detectors anyway.
Insert opaque wires Insert opaque wires where dark patches where dark patches would be expected would be expected
from a wave.from a wave.
The Afshar ConclusionsThe Afshar Conclusions
A photon can be a particle A photon can be a particle andand a wave a wave at at the same time.the same time.
Wave interference happens Wave interference happens afterafter the the photon path is identified, so the photon path is identified, so the Copenhagen interpretation is wrong.Copenhagen interpretation is wrong.
Both conclusions are flawed,Both conclusions are flawed,but they but they mightmight be correct. be correct.
The Afshar’s ConclusionsThe Afshar’s Conclusions
A photon can be a particle A photon can be a particle andand a wave a wave at the same time.at the same time.
But the photon is notin these two places
at the same time.
The Afshar’s ConclusionsThe Afshar’s Conclusions
Wave interference happens Wave interference happens afterafter the the photon path is identified, so the photon path is identified, so the Copenhagen interpretation is wrong.Copenhagen interpretation is wrong.
Afshar observes:If the photon travelsthrough pinhole #1,then it winds up at
detector #1.
Afshar concludes:If the photon arrived
at detector #1then it came
through pinhole #1.
These are not the same statement!These are not the same statement!
Peek-A-Boo logic is at work.Peek-A-Boo logic is at work.
The Afshar ExperimentThe Afshar Experiment
Key Question: Key Question: What does the Copenhagen interpretation What does the Copenhagen interpretation predict will happen?predict will happen?
Surprising Answer:Surprising Answer:
Afshar illustrates new Afshar illustrates new physics physics andand the fallacy the fallacy of Peek-A-Boo logic.of Peek-A-Boo logic.
ThisThis
Lessons from AfsharLessons from Afshar
Peek-A-Boo Logic infects even Peek-A-Boo Logic infects even expert minds.expert minds.
Peek-A-Boo logic is unreliable.Peek-A-Boo logic is unreliable.
But the Copenhagen interpretation But the Copenhagen interpretation just mightjust might be wrong. be wrong.
Principle #2: FingerprintsPrinciple #2: Fingerprints
Fingerprints, Cupcakes, and Reality
The Cupcake Problem:The Cupcake Problem:
Alice and the Rabbit had six Alice and the Rabbit had six cupcakes all together.cupcakes all together.
They split the cupcakes evenly They split the cupcakes evenly between them.between them.
Create a Create a representationrepresentation to show to show how the cupcakes were split.how the cupcakes were split.
The Cupcake Problem:The Cupcake Problem:
Alice Rabbit
Cupcake Logic:Cupcake Logic:
Alice Rabbit
Q: How many cupcakes did Alice get?
A: Three.
Easy question #1:
Cupcake Logic:Cupcake Logic:
Q: Which three did Alice get?
A: The yellow, pink, and green ones.
Alice Rabbit
Easy question #2:
Cupcake Logic:Cupcake Logic:
2 =
More easy questions:
Q: What is six divided by two?A: Three.
Q: Which three???
Cupcake Logic:Cupcake Logic:
We call this “reality”…
but not this…
2 =
Why Not?
The Myth of Fingerprints:The Myth of Fingerprints:
Distinguishability Distinguishability Objects are different and Objects are different and
we can distinguish them.we can distinguish them. I recognize my mom.I recognize my mom.
Fingerprints and PhysicsFingerprints and Physics
All protons are alike.All protons are alike.
All electrons are alike.All electrons are alike.
Not just similar as with identical twins.But completely indistinguishable.Even THEY can’t tell them apart.
Fingerprints and PhysicsFingerprints and Physics
All protons are alike.All protons are alike.
All electrons are alike.All electrons are alike.
Evidence!
The Mandel ExperimentThe Mandel Experiment
Leonard Mandel (1995)Leonard Mandel (1995)
DistinguishedDistinguishedphotonsphotons
The Mandel ExperimentThe Mandel Experiment
Shoot identical photons (or electrons) through two slits. Will we get…
INTERFERENCE
NO INTERFERENCE?
The Mandel ExperimentThe Mandel Experiment
Now block Left slit. Photons only go through Right slit. Will we get…
INTERFERENCE
NO INTERFERENCE?
The Mandel ExperimentThe Mandel Experiment
Shoot distinguishable photons from two lasers. Will we get…
INTERFERENCE
NO INTERFERENCE?
The Mandel ExperimentThe Mandel Experiment
Shoot identical photons but put a detector over one slit. Will we get…
INTERFERENCE
NO INTERFERENCE?
The Mandel ExperimentThe Mandel Experiment
Same experiment, but turn the detector OFF (no human observer). Will we get…
INTERFERENCE
NO INTERFERENCE?!!!
The Mandel ExperimentThe Mandel Experiment
Human observation is not necessary for Human observation is not necessary for quantum measurement effects!quantum measurement effects!
The issue is not whether or not The issue is not whether or not humanshumans have information from a measurement.have information from a measurement.
The issue isThe issue is whether or not the whether or not the information exists!information exists!
Mandel and Schrödinger’s CatMandel and Schrödinger’s Cat
Erwin Schrödinger (1935)
Schrodinger does not need to observe the cat for it to be
definitely dead or definitely alive. The presence of the cat is enough!
Thanks to Mandel,the paradox of Schrodinger’s cat is …
Mandel and Schrödinger’s CatMandel and Schrödinger’s Cat
Erwin Schrödinger (1935)
Thanks to Mandel, the paradox of Schrodinger’s cat is GONE!
Mandel and Schrödinger’s CatMandel and Schrödinger’s Cat
Erwin Schrödinger (1935)
Thanks to Mandel, the paradox of Schrodinger’s cat is GONE!
You saw that coming,
Didn’t you?
The smile of Schrödinger’s cat:
What does it mean for information to “exist”?
The Mandel ExperimentThe Mandel Experiment
Put detectors on BOTH slits. Will we get…
INTERFERENCE
NO INTERFERENCE?
Good question!
The Mandel ExperimentThe Mandel Experiment
Important details:
White boxes are crystals.
When original photons go through, the crystals send extra photons “sideways” to waiting detectors.
Left Detector
Right Detector
The Mandel ExperimentThe Mandel Experiment
As shown here...
Left Detector
Right Detector
INTERFERENCE
NO INTERFERENCE?
The Mandel ExperimentThe Mandel Experiment
But what if we mix the “sideways” photons together?
Does the behavior of the “forwards” photons change?
Lonely Detector
“Both” Detector
The Mandel ExperimentThe Mandel Experiment
Lonely Detector
As shown here...
INTERFERENCE
NO INTERFERENCE?
“Both” Detector
How does the fate of these photons…
What is “information”?
… influence these photons?
Lessons from MandelLessons from Mandel
Human observation does not Human observation does not create the universe.create the universe.
Distinguishability rules quantum Distinguishability rules quantum mechanics.mechanics.
Meaning of the word “information” Meaning of the word “information” is important, but not obvious.is important, but not obvious.
The Travel Principle:The Travel Principle:
Are we there yet? No.
The Travel Principle:The Travel Principle:
We can’t experience “there” unlessWe can’t experience “there” unless
A) We go “there”, orA) We go “there”, or
B) Something from “there” comes “here”.B) Something from “there” comes “here”.
The fastest anything can travel isThe fastest anything can travel isc = 700 million mphc = 700 million mph
The Travel Principle:The Travel Principle:
Nothing that happens Nothing that happens on the moon can on the moon can influence us for…influence us for…
one second.one second.
The Travel Principle:The Travel Principle:
No influence or information from the No influence or information from the sun can reach us for…sun can reach us for…
eight minutes.eight minutes.
The Travel Principle:The Travel Principle:
Scientists call this idea Scientists call this idea ““LocalityLocality.”.”
Without “locality” someWithout “locality” somephysicists fear for “causality.”physicists fear for “causality.”
The Aspect ExperimentThe Aspect Experiment
Alain Aspect (1982)Alain Aspect (1982)
PhotonsPhotonsfar flungfar flung
The Aspect ExperimentThe Aspect Experiment
But first a word from Einstein…But first a word from Einstein…Some radioactive atoms emit Some radioactive atoms emit pairspairs of of
particles with opposite properties.particles with opposite properties.
Einstein (1935)Einstein (1935)
The Aspect ExperimentThe Aspect Experiment
Einstein (1935)Einstein (1935)
Measure a property of
this guy.
This guy willhave the opposite
property.
The Aspect ExperimentThe Aspect Experiment
Einstein (1935)Einstein (1935)
“Copenhagen” says this guy’s properties are undefined until measurement happens here.
But that measurement would have an instant
effect here.
Instant action at a distance isn’tpossible, so quantum mechanics
must not be “complete.”
There is more information(aka “hidden variables”).
All physics is local.
The Aspect ExperimentThe Aspect Experiment
John Bell (1966)John Bell (1966)
Einstein’s locality and quantum mechanics are distinct. An experiment could distinguish them.
The Aspect ExperimentThe Aspect Experiment
Goal #1: Explore Bell’s Inequalities.Goal #1: Explore Bell’s Inequalities.Goal #2: measure the Goal #2: measure the LEFTLEFT photon before a photon before a signal from the signal from the RIGHTRIGHT photon could reach it. photon could reach it.
Alain Aspect’s experiment, 1982.
The Aspect ExperimentThe Aspect Experiment
Some said Aspect’s labSome said Aspect’s labwasn’t big enough. wasn’t big enough.
Aspect’s resultsAspect’s resultssupported non-locality supported non-locality
(99% confidence level)(99% confidence level)
The Aspect ExperimentThe Aspect Experiment
CERN took care of that in 1998. CERN took care of that in 1998.
7 miles!
The Aspect ExperimentThe Aspect Experiment
And the work has been repeated… And the work has been repeated…
Calgary, 2001Calgary, 2001 Harvard, 1998Harvard, 1998
Lessons from AspectLessons from Aspect
Did Bell’s Theorem and the Did Bell’s Theorem and the Aspect Experiments Aspect Experiments killkill locality? locality?
““No. Locality met it’s own demise.”No. Locality met it’s own demise.”John Bell John Bell ..
The Restaurant PrincipleThe Restaurant Principle
Welcome to the Welcome to the Quantum CaféQuantum Café
How about How about dessert?dessert?
Quantum CaféQuantum Café
Dessert MenuYou may order:
Cake
Ice Cream
Something Chocolate
Something Vanilla
Your order will be delivered instantaneously.
Just ask your waiter.
On other people’s tablesOn other people’s tables
Looks pretty good, so…Looks pretty good, so…
I want something chocolate.
I want some cake.
I want some ice cream.
The Restaurant PrincipleThe Restaurant Principle
Maybe this guy only has Maybe this guy only has two things.two things.
He could have those He could have those two things two things hidden, hidden,
Maybe this guy only has Maybe this guy only has two things.two things.
He could have those He could have those two things two things hidden, hidden, and then he pulls and then he pulls
out whicheverout whicheverone works.one works.
Let’s check…Let’s check…
I want vanilla ice cream.
Ah ha!
Watch this!I want vanilla
ice cream.
Um…
I want vanilla ice cream???
One more time…I want vanilla
ice cream.
You’re messing with me, aren’t you?
The Restaurant PrincipleThe Restaurant Principle
I should get what I order.I should get what I order.
What’s in the kitchen should What’s in the kitchen should determine what I determine what I cancan order. order.
Stuff in the kitchen shouldn’t Stuff in the kitchen shouldn’t change when I change when I dodo order. order.
Scientists call thisScientists call this“Determinism”“Determinism”
The Restaurant PrincipleThe Restaurant Principle
At the quantum café, At the quantum café, only half of our requests are granted.only half of our requests are granted.
The other half are The other half are completelycompletely random. random.
What would the ingredients
look like?
The Restaurant PrincipleThe Restaurant Principle
Some pairs of properties Some pairs of properties cannot be specified at the cannot be specified at the same time.same time.
Mother Nature herself can’t Mother Nature herself can’t control them in advance.control them in advance.
Werner Heisenberg Werner Heisenberg (1927)(1927)
Uncertainty
The Zeilinger ExperimentThe Zeilinger Experiment
Uncertainty Uncertainty vs. vs.
DeterminismDeterminism
Anton Zeilinger (2000)Anton Zeilinger (2000)
The Zeilinger ExperimentThe Zeilinger Experiment
““Entangle” Entangle” threethree photons “anti-symmetrically” photons “anti-symmetrically” Force one value of “polarization”Force one value of “polarization” Check the polarization of the other twoCheck the polarization of the other two
These two are forced to point down.
Force this one to
“point up”
• Deterministic Picture:
The Zeilinger ExperimentThe Zeilinger Experiment
““Entangle” Entangle” threethree photons “anti-symmetrically” photons “anti-symmetrically” Force one value of “polarization”Force one value of “polarization” Check the polarization of the other twoCheck the polarization of the other two
• Anti-symmetric QM:
Force this one to
“point up”These two are forced into an anti-symmetric
superposition state.
Observation “collapses” the superposition with one vector
“up” and one “down”
The Zeilinger ExperimentThe Zeilinger Experiment
The results are “0 up”, “1 up”, “2 up”, or “3 up”The results are “0 up”, “1 up”, “2 up”, or “3 up” No fuzzy statistical uncertainties!No fuzzy statistical uncertainties! The predictions are…The predictions are…
Local determinism:Local determinism:None of the others agreeNone of the others agree
Uncertain quantum physics:Uncertain quantum physics:One photon agrees with the 1stOne photon agrees with the 1st
The Zeilinger ExperimentThe Zeilinger Experiment
Zeilinger’s results:Zeilinger’s results: Quantum Mechanics wins out…Quantum Mechanics wins out…
… …every timeevery time
Local determinism:Local determinism:None of the others agreeNone of the others agree
Uncertain quantum physics:Uncertain quantum physics:One photon agrees with the 1stOne photon agrees with the 1st
Other variations have all favored quantum uncertainty
Lessons from ZeilingerLessons from Zeilinger
Locality and Determinism can’t both be correct.
It doesn’t look good for determinism.
But the flip side of determinism is…
Free WillFree Will
What is free will?What is free will?
Presence of conscious intentPresence of conscious intent“I want to do something.”“I want to do something.”
Absence of predeterminationAbsence of predetermination“My future includes choices.”“My future includes choices.”
Free Will made simple:Free Will made simple:
Free WillFree Will
John Conway (2006)John Conway (2006)
If quantum states are uncertain, then humans and
particles have free will.
If not, particle behavior is predetermined,
and so is ours.
But…But…
Conway’s argument depends Conway’s argument depends on our ability to work at long on our ability to work at long distance at infinite speed.distance at infinite speed.
He He assumesassumes non-locality. non-locality.
John Conway’s “Free Will Theorem”John Conway’s “Free Will Theorem”
The Reality Roster:The Reality Roster:
1.1. Object permanenceObject permanence (Peek-A-Boo)(Peek-A-Boo) On the injured list
2.2. Distinguishability Distinguishability (Fingerprints) (Fingerprints) Dead
3.3. LocalityLocality (Travel) (Travel) Critical condition
4.4. Determinism Determinism (Restaurants) (Restaurants) Breathing on life support
(Note: (Note: LocalityLocality and and DeterminismDeterminism share one kidney between them.)share one kidney between them.)
Science and ReligionScience and Religion
““I do believe,” said Alice at I do believe,” said Alice at last… “I’ll just call and say last… “I’ll just call and say
‘How do you do?’ and ‘How do you do?’ and ask them the way ask them the way
out of the wood.”out of the wood.”
Artwork by John Tenniel
The Red King’s DreamThe Red King’s Dream
The Red King is sleeping. The Red King is sleeping.
Tweedledee: “You’re only a thing in his dream.”Tweedledee: “You’re only a thing in his dream.”
Tweedledum: “If that there King was to wake, you'd Tweedledum: “If that there King was to wake, you'd go out -- bang! -- just like a candle!”go out -- bang! -- just like a candle!”
The Red King’s DreamThe Red King’s Dream
Alice wakes to find that Alice wakes to find that sheshe had been dreaming. had been dreaming.
Lewis Carroll asks: “Which dreamed it?”Lewis Carroll asks: “Which dreamed it?”Was Wonderland Was Wonderland reallyreally created by Alice’s dream? created by Alice’s dream?Was Alice’s world created by the King’s dream?Was Alice’s world created by the King’s dream?Or was none of it real at all?Or was none of it real at all?
Wonderland created by Alice:Wonderland created by Alice:
We are all observers.We are all observers.
The universe snaps The universe snaps into existence as we into existence as we observe it.observe it.
Everyone and Everyone and everything is God.everything is God. 2004
(And we influence the outcomes.)
Reality created by the Red King:Reality created by the Red King:Quantum mechanics Quantum mechanics
requires an observer.requires an observer.
There must have been There must have been an observer before there an observer before there were humans.were humans.
Therefore God exists.Therefore God exists.
2003
Or none of it is real:Or none of it is real:Wonderland and the Wonderland and the
Red King are imaginary.Red King are imaginary.
Our physical universe is Our physical universe is governed by chance.governed by chance.
Quantum physics is Quantum physics is absurd.absurd.
Only a lunatic would Only a lunatic would create this universe.create this universe. 2007
The Great The Great MisinterpretationMisinterpretation::
Many interpret the Copenhagen model Many interpret the Copenhagen model of quantum mechanics to mean:of quantum mechanics to mean:
Quantum mechanics requiresQuantum mechanics requires conscious observationconscious observation in order in orderfor reality to take definite shape.for reality to take definite shape.
Mandel, Aspect, and Zeilinger have all Mandel, Aspect, and Zeilinger have all shown this is not necessarily true.shown this is not necessarily true.
Room for Room for InterpretationInterpretation::
The misinterpretation is that:The misinterpretation is that:
Quantum mechanics Quantum mechanics requiresconscious observationconscious observation in order in orderfor reality to take definite shape.for reality to take definite shape.
The correct reading should be...The correct reading should be...
allows
The Great The Great MisinterpretationMisinterpretation::
Science and ReligionScience and Religion
All 3 are possible interpretations of modern physics.All 3 lie outside of the realm of science.
Why worry about the confusion?Why worry about the confusion?
What’s wrong with What’s wrong with injecting religion injecting religion
into science?into science?
“I think you should be more explicit here in step two.”
The fine lineThe fine line
Where doesWhere does
injecting religion into science endinjecting religion into science end
and rejecting science begin?and rejecting science begin?
Artwork by Julie Inman
If our religion doesn’t fit If our religion doesn’t fit in the rabbit hole…in the rabbit hole…
Do we simply kill Do we simply kill the rabbit?the rabbit?
The fine lineThe fine line
How do we combine How do we combine science science andand religion? religion?
Do we have to Do we have to make a choice?make a choice?
Artwork by Ken Wong
“The net of science covers the empirical realm…The net of religion extends over questions of moral meaning and value. These two magisteria do not overlap, nor do they encompass all inquiry.”
Stephen Jay Gould
Albert Einstein “Imagination is moreimportant than knowledge, for … imagination embraces … all there ever will be to know.”
“If something is in me which can be called religious then it is an unbounded admiration for the structure of the world so far as our science can reveal it.”
“Religion, Art, and Science are branches of the same tree.”
Artwork by Julian Voss-Andrae
“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”
Hamlet, Act I, Scene V
“What we need is imagination, but imagination in a terrible strait-jacket. We have to find a view of the world but that view has to agree with nature.”
Richard Feynman
“Nothing is too wonderful to be consistent with the laws of nature.”
Michael Faraday
Artwork by Julian Voss-AndraeExperiment by Jennifer Sebby-Strabley
The EndThe End
Lingering in the golden gleam,
Life, what is it but a dream?”
Lewis Carroll
“Still she haunts me, phantomwise,
Alice moving under skies…