Transcript Quantum Weirdness

An Epic Poem...
Dear Cecil:
Cecil, you're my final hope
Of finding out the true Straight Dope
For I have been reading of Schroedinger's cat
But none of my cats are at all like that.
This unusual animal (so it is said)
Is simultaneously live and dead!
What I don't understand is just why he
Can't be one or other, unquestionably.
My future now hangs in between eigenstates.
In one I'm enlightened, the other I ain't.
If you understand, Cecil, then show me the way
And rescue my psyche from quantum decay.
But if this queer thing has perplexed even you,
Then I will and won't see you in Schroedinger's zoo.
--Randy F., Chicago
An Epic Reply...
Dear Randy:
Schroedinger, Erwin! Professor of physics!
Wrote daring equations! Confounded his critics!
(Not bad, eh? Don't worry. This part of the verse
Starts off pretty good, but it gets a lot worse.)
When saw that the theory that Newton'd invented
By Einstein's discov'ries had been badly dented.
What now? wailed his colleagues. Said Erwin, "Don't panic,
No grease monkey I, but a quantum mechanic.
Consider electrons. Now, these teeny articles
Are sometimes like waves, and then sometimes like particles.
If that's not confusing, the nuclear dance
Of electrons and suchlike is governed by chance!
No sweat, though--my theory permits us to judge
Where some of 'em is and the rest of 'em was."
Not everyone bought this. It threatened to wreck
The comforting linkage of cause and effect.
E'en Einstein had doubts, and so Schroedinger tried
To tell him what quantum mechanics implied.
Said Win to Al, "Brother, suppose we've a cat,
And inside a tube we have put that cat at-Along with a solitaire deck and some Fritos,
A bottle of Night Train, a couple mosquitoes
(Or something else rhyming) and, oh, if you got 'em,
One vial prussic acid, one decaying ottom
Or atom--whatever--but when it emits,
A trigger device blasts the vial into bits
Which snuffs our poor kitty. The odds of this crime
Are 50 to 50 per hour each time.
The cylinder's sealed. The hour's passed away. Is
Our pussy still purring--or pushing up daisies?
Now, you'd say the cat either lives or it don't
But quantum mechanics is stubborn and won't.
Statistically speaking, the cat (goes the joke),
Is half a cat breathing and half a cat croaked.
To some this may seem a ridiculous split,
But quantum mechanics must answer, "Tough @#&!
We may not know much, but one thing's fo' sho':
There's things in the cosmos that we cannot know.
Shine light on electrons--you'll cause them to swerve.
The act of observing disturbs the observed-Which ruins your test. But then if there's no testing
To see if a particle's moving or resting
Why try to conjecture? Pure useless endeavor!
We know probability--certainty, never.'
The effect of this notion? I very much fear
'Twill make doubtful all things that were formerly clear.
Till soon the cat doctors will say in reports,
"We've just flipped a coin and we've learned he's a corpse."'
So saith Herr Erwin. Quoth Albert, "You're nuts.
God doesn't play dice with the universe, putz.
I'll prove it!" he said, and the Lord knows he tried-In vain--until fin'ly he more or less died.
Win spoke at the funeral: "Listen, dear friends,
Sweet Al was my buddy. I must make amends.
Though he doubted my theory, I'll say of this saint:
Ten-to-one he's in heaven--but five bucks says he ain't."
--CECIL ADAMS
Is the World What it Seems?
• The classical world (prior to 1900)
consisted of:
•waves
•particles
•forces
• Let’s tour this familiar terrain...
A place for everything and
everything in its ...
• Light - an enduring mystery revealed! (go to
applet on slit-interference)
• Atoms - small but “true”!
• May the force(s) be with you!
The physical universe - understandable in
terms of waves, particles and forces!
Just when Physicists thought they
had it made!
• Lord Kelvin’s Two Dark Clouds!
– The Michelson-Morley expt
– BlackBody Radiation
hey - now that you mention it...
other strange findings...
• photoelectric effect
• atomic spectra
• Compton scattering
The Great Heresy!
• A wave “is a particle”
• A particle “is a wave”
The Schroedinger Equation and Heisenberg’s
Matrix Mechanics...
...a fundamental blurring of the universe
It looks like Heisenberg - I think,
I’m pretty sure, I’m not certain...
The Uncertainty
Principle
The Copenhagen Interpretation...
• QM is a complete theory
that tells us that the world,
at the quantum level, is
governed by statistical law.
It rules out “classical” or
“naïve” realist views of
nature. As an example,
consider the following
applet demonstrating the
Hydrogen atom.
The EPR Effect, Bell’s Theorem
and Quantum Weirdness
• GOD does not play dice!
• Hidden Variable Theories and Bell’s
Theorem
• The Death of classical (perhaps even
critical?) realism
• Anti-realism and other interpretations of
QM
And the Winner Is ...
• The majority (by far) of physicists subscribe to the
Copenhagen interpretation(s) of QM. This is the
dominant paradigm for physics and it is difficult
(butnot impossible) for other views to be put
forward.
Ironic isn’t it...
• In Kuhnian terms, with the entrenchment of a paradigm,
foundational questions are pushed aside and most
physicists spend their time elaborating the paradigm. The
irony is that QM is the most successful theory ever devised
and, as it is daily confirmed, it further entrenches the
paradigm that assures us that there is no deep reality. It will
only be questioned when anomolies begin to emerge and
so far none have! When pushed, most physicists adopt an
intrumentalist position - QM is just a tool for predicting not explaining.
Some Questions ...
• QM - regardless of the interpretation that you
choose - radically alters our conception of what
"physical reality" entails. If you adopt the stance
that Theology also speaks about reality (including
the physical) does QM pose any challenges for
Theology?
• if the world is indeterministic (or has that built in at some
level) does this constrain "god" - does this "push" in the
direction of Process Theology?
Some Questions ...
• Could "god" operate within the indeterminism of QM?
(Instead of many worlds - perhaps "god selects" which
wavefunction will be promoted etc)