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Hi Phil,<br><br>
I have renamed the three participants in V2020 quantum mechanics debate
X, Y, and Z, and I've sent the text to three physicists for their
review. This is the first blind peer review, as far as I know, of
contents of the Vision.<br><br>
Until I hear from the referees, I'm appending the following
article. My thanks to Wayne Fox for finding this.<br><br>
The article makes an important distinction between quantum theory and
quantum mechanics. Phil, you are right that Einstein contributed to
the development of the first, but the main point I wanted to make was
that he fought to the bitter end the development of quantum mechanics
based on probability and Heisenberg's uncertainty principle.<br><br>
Philosophically, Phil, I am committed to "realism" as much as
you are. This is the common sense view that the world exists
independent from our perception of it. But as this article points
out, our common sense continues to be insulted and undermined by
discovery after discovery at the sub-atomic level. <br><br>
My apologies to those who only want to discuss local city and county
issues. The wide variety of topics and unmoderated format is what
makes me a Vision Addict.<br><br>
Happy New Year,<br><br>
Nick Gier<br><br>
The New York Times <br>
December 27, 2005<br><br>
Quantum Trickery: Testing Einstein's Strangest Theory<br><br>
By DENNIS OVERBYE<br><br>
Einstein said there would be days like this.<br><br>
This fall scientists announced that they had put a half dozen
beryllium<br>
atoms into a "cat state."<br><br>
No, they were not sprawled along a sunny windowsill. To a physicist,
a<br>
"cat state" is the condition of being two diametrically
opposed<br>
conditions at once, like black and white, up and down, or dead and
alive.<br><br>
These atoms were each spinning clockwise and counterclockwise at
the<br>
same time. Moreover, like miniature Rockettes they were all doing<br>
whatever it was they were doing together, in perfect synchrony.
Should<br>
one of them realize, like the cartoon character who runs off a cliff
and<br>
doesn't fall until he looks down, that it is in a metaphysically<br>
untenable situation and decide to spin only one way, the rest would<br>
instantly fall in line, whether they were across a test tube or
across<br>
the galaxy.<br><br>
The idea that measuring the properties of one particle could<br>
instantaneously change the properties of another one (or a whole
bunch)<br>
far away is strange to say the least - almost as strange as the
notion<br>
of particles spinning in two directions at once. The team that
pulled<br>
off the beryllium feat, led by Dietrich Leibfried at the National<br>
Institute of Standards and Technology, in Boulder, Colo., hailed it
as<br>
another step toward computers that would use quantum magic to
perform<br>
calculations.<br><br>
But it also served as another demonstration of how weird the world<br>
really is according to the rules, known as quantum mechanics.<br><br>
The joke is on Albert Einstein, who, back in 1935, dreamed up this
trick<br>
of synchronized atoms - "spooky action at a distance," as he
called it -<br>
as an example of the absurdity of quantum mechanics.<br><br>
"No reasonable definition of reality could be expected to permit
this,"<br>
he, Boris Podolsky and Nathan Rosen wrote in a paper in 1935.<br><br>
Today that paper, written when Einstein was a relatively ancient 56<br>
years old, is the most cited of Einstein's papers. But far from<br>
demolishing quantum theory, that paper wound up as the cornerstone
for<br>
the new field of quantum information.<br><br>
Nary a week goes by that does not bring news of another feat of
quantum<br>
trickery once only dreamed of in thought experiments: particles (or
at<br>
least all their properties) being teleported across the room in a<br>
microscopic version of Star Trek beaming; electrical "cat"
currents that<br>
circle a loop in opposite directions at the same time; more and
more<br>
particles farther and farther apart bound together in Einstein's
spooky<br>
embrace now known as "entanglement." At the University of
California,<br>
Santa Barbara, researchers are planning an experiment in which a
small<br>
mirror will be in two places at once.<br><br>
Niels Bohr, the Danish philosopher king of quantum theory, dismissed
any<br>
attempts to lift the quantum veil as meaningless, saying that
science<br>
was about the results of experiments, not ultimate reality. But now
that<br>
quantum weirdness is not confined to thought experiments,
physicists<br>
have begun arguing again about what this weirdness means, whether
the<br>
theory needs changing, and whether in fact there is any
problem.<br><br>
This fall two Nobel laureates, Anthony Leggett of the University of<br>
Illinois and Norman Ramsay of Harvard argued in front of several
hundred<br>
scientists at a conference in Berkeley about whether, in effect,<br>
physicists were justified in trying to change quantum theory, the
most<br>
successful theory in the history of science. Dr. Leggett said yes;
Dr.<br>
Ramsay said no.<br><br>
It has been, as Max Tegmark, a cosmologist at the Massachusetts<br>
Institute of Technology, noted, "a 75-year war." It is typical
in<br>
reporting on this subject to bounce from one expert to another, each
one<br>
shaking his or her head about how the other one just doesn't get
it.<br>
"It's a kind of funny situation," N. David Mermin of Cornell,
who has<br>
called Einstein's spooky action "the closest thing we have to
magic,"<br>
said, referring to the recent results. "These are extremely
difficult<br>
experiments that confirm elementary features of quantum mechanics."
It<br>
would be more spectacular news, he said, if they had come out
wrong.<br><br>
Anton Zeilinger of the University of Vienna said that he thought,
"The<br>
world is not as real as we think.<br><br>
"My personal opinion is that the world is even weirder than what
quantum<br>
physics tells us," he added.<br><br>
The discussion is bringing renewed attention to Einstein's role as
a<br>
founder and critic of quantum theory, an "underground history,"
that has<br>
largely been overlooked amid the celebrations of relativity in the
past<br>
Einstein year, according to David Z. Albert, a professor of
philosophy<br>
and physics at Columbia. Regarding the 1935 paper, Dr. Albert said,
"We<br>
know something about Einstein's genius we didn't know
before."<br><br>
*The Silly Theory*<br><br>
From the day 100 years ago that he breathed life into quantum theory
by<br>
deducing that light behaved like a particle as well as like a wave,<br>
Einstein never stopped warning that it was dangerous to the age-old<br>
dream of an orderly universe.<br><br>
If light was a particle, how did it know which way to go when it
was<br>
issued from an atom?<br><br>
"The more success the quantum theory has, the sillier it
seems,"<br>
Einstein once wrote to friend.<br><br>
The full extent of its silliness came in the 1920's when quantum
theory<br>
became quantum mechanics.<br><br>
In this new view of the world, as encapsulated in a famous equation
by<br>
the Austrian Erwin Schrödinger, objects are represented by waves
that<br>
extend throughout space, containing all the possible outcomes of an<br>
observation - here, there, up or down, dead or alive. The amplitude
of<br>
this wave is a measure of the probability that the object will
actually<br>
be found to be in one state or another, a suggestion that led
Einstein<br>
to grumble famously that God doesn't throw dice.<br><br>
Worst of all from Einstein's point of view was the uncertainty<br>
principle, enunciated by Werner Heisenberg in 1927.<br><br>
Certain types of knowledge, of a particle's position and velocity,
for<br>
example, are incompatible: the more precisely you measure one
property,<br>
the blurrier and more uncertain the other becomes.<br><br>
In the 1935 paper, Einstein and his colleagues, usually referred to
as<br>
E.P.R., argued that the uncertainty principle could not be the
final<br>
word about nature. There must be a deeper theory that looked behind
the<br>
quantum veil.<br><br>
Imagine that a pair of electrons are shot out from the disintegration
of<br>
some other particle, like fragments from an explosion. By law
certain<br>
properties of these two fragments should be correlated. If one goes<br>
left, the other goes right; if one spins clockwise, the other spins<br>
counterclockwise.<br><br>
That means, Einstein said, that by measuring the velocity of, say,
the<br>
left hand electron, we would know the velocity of the right hand<br>
electron without ever touching it.<br><br>
Conversely, by measuring the position of the left electron, we
would<br>
know the position of the right hand one.<br><br>
Since neither of these operations would have involved touching or<br>
disturbing the right hand electron in any way, Einstein, Podolsky
and<br>
Rosen argued that the right hand electron must have had those
properties<br>
of both velocity and position all along. That left only two<br>
possibilities, they concluded. Either quantum mechanics was<br>
"incomplete," or measuring the left hand particle somehow
disturbed the<br>
right hand one.<br><br>
But the latter alternative violated common sense. Such an influence,
or<br>
disturbance, would have to travel faster than the speed of light.
"My<br>
physical instincts bristle at that suggestion," Einstein later
wrote.<br><br>
Bohr responded with a six-page essay in Physical Review that
contained<br>
but one simple equation, Heisenberg's uncertainty relation. In
essence,<br>
he said, it all depends on what you mean by
"reality."<br><br>
*Enjoy the Magic*<br><br>
Most physicists agreed with Bohr, and they went off to use quantum<br>
mechanics to build atomic bombs and reinvent the world.<br><br>
The consensus was that Einstein was a stubborn old man who "didn't
get"<br>
quantum physics. All this began to change in 1964 when John S. Bell,
a<br>
particle physicist at the European Center for Nuclear Research near<br>
Geneva, who had his own doubts about quantum theory, took up the
1935<br>
E.P.R. argument. Somewhat to his dismay, Bell, who died in 1990,
wound<br>
up proving that no deeper theory could reproduce the predictions of<br>
quantum mechanics. Bell went on to outline a simple set of
experiments<br>
that could settle the argument and decide who was right, Einstein or
Bohr.<br><br>
When the experiments were finally performed in 1982, by Alain Aspect
and<br>
his colleagues at the University of Orsay in France, they agreed
with<br>
quantum mechanics and not reality as Einstein had always presumed
it<br>
should be. Apparently a particle in one place could be affected by
what<br>
you do somewhere else.<br><br>
"That's really weird," Dr. Albert said, calling it "a
profoundly deep<br>
violation of an intuition that we've been walking with since caveman
days."<br><br>
Physicists and philosophers are still fighting about what this
means.<br>
Many of those who care to think about these issues (and many prefer
not<br>
to), concluded that Einstein's presumption of locality - the idea
that<br>
physically separated objects are really separate - is wrong.<br><br>
Dr. Albert said, "The experiments show locality is false, end of
story."<br>
But for others, it is the notion of realism, that things exist<br>
independent of being perceived, that must be scuttled. In fact,<br>
physicists don't even seem to agree on the definitions of things
like<br>
"locality" and "realism."<br><br>
"I would say we have to be careful saying what's real," Dr.
Mermin said.<br>
"Properties cannot be said to be there until they are revealed by
an<br>
actual experiment."<br><br>
What everybody does seem to agree on is that the use of this effect
is<br>
limited. You can't use it to send a message, for example.<br><br>
Leonard Susskind, a Stanford theoretical physicist, who called
these<br>
entanglement experiments "beautiful and surprising," said the
term<br>
"spooky action at a distance," was misleading because it
implied the<br>
instantaneous sending of signals. "No competent physicist thinks
that<br>
entanglement allows this kind of nonlocality."<br><br>
Indeed the effects of spooky action, or "entanglement," as
Schrödinger<br>
called it, only show up in retrospect when the two participants in
a<br>
Bell-type experiment compare notes. Beforehand, neither has seen
any<br>
violation of business as usual; each sees the results of his<br>
measurements of, say, whether a spinning particle is pointing up or<br>
down, as random.<br><br>
In short, as Brian Greene, the Columbia theorist wrote in "The
Fabric of<br>
the Cosmos," Einstein's special relativity, which sets the speed
of<br>
light as the cosmic speed limit, "survives by the skin of its
teeth."<br><br>
In an essay in 1985, Dr. Mermin said that "if there is spooky action
at<br>
a distance, then, like other spooks, it is absolutely useless except
for<br>
its effect, benign or otherwise, on our state of mind."<br><br>
He added, "The E.P.R. experiment is as close to magic as any
physical<br>
phenomenon I know of, and magic should be enjoyed." In a
recent<br>
interview, he said he still stood by the latter part of that
statement.<br>
But while spooky action remained useless for sending a direct
message,<br>
it had turned out to have potential uses, he admitted, in
cryptography<br>
and quantum computing.<br><br>
*Nine Ways of Killing a Cat*<br><br>
Another debate, closely related to the issues of entanglement and<br>
reality, concerns what happens at the magic moment when a particle
is<br>
measured or observed.<br><br>
Before a measurement is made, so the traditional story goes, the<br>
electron exists in a superposition of all possible answers, which
can<br>
combine, adding and interfering with one another.<br><br>
Then, upon measurement, the wave function "collapses" to one
particular<br>
value. Schrödinger himself thought this was so absurd that he dreamed
up<br>
a counterexample. What is true for electrons, he said, should be true
as<br>
well for cats.<br><br>
In his famous thought experiment, a cat is locked in a box where
the<br>
decay of a radioactive particle will cause the release of poison
that<br>
will kill it. If the particle has a 50-50 chance of decaying, then<br>
according to quantum mechanics the cat is both alive and dead before
we<br>
look in the box, something the cat itself, not to mention cat
lovers,<br>
might take issue with.<br><br>
But cats are always dead or alive, as Dr. Leggett of Illinois said
in<br>
his Berkeley talk. "The problem with quantum mechanics," he
said in an<br>
interview, "is how it explains definite outcomes to
experiments."<br><br>
If quantum mechanics is only about information and a way of
predicting<br>
the results of measurements, these questions don't matter, most
quantum<br>
physicists say.<br><br>
"But," Dr. Leggett said, "if you take the view that the
formalism is<br>
reflecting something out there in real world, it matters immensely."
As<br>
a result, theorists have come up with a menu of alternative<br>
interpretations and explanations. According to one popular notion,
known<br>
as decoherence, quantum waves are very fragile and collapse from
bumping<br>
into the environment. Another theory, by the late David Bohm,
restores<br>
determinism by postulating a "pilot wave" that acts behind the
scenes to<br>
guide particles.<br><br>
In yet another theory, called "many worlds," the universe
continually<br>
branches so that every possibility is realized: the Red Sox win and
lose<br>
and it rains; Schrödinger's cat lives, dies, has kittens and
scratches<br>
her master when he tries to put her into the box.<br><br>
Recently, as Dr. Leggett pointed out, some physicists have tinkered
with<br>
Schrödinger's equation, the source of much of the misery,
itself.<br><br>
A modification proposed by the Italian physicists Giancarlo Ghirardi
and<br>
Tullio Weber, both of the University of Trieste, and Alberto Rimini
of<br>
the University of Pavia, makes the wave function unstable so that
it<br>
will collapse in a time depending on how big a system it
represents.<br><br>
In his standoff with Dr. Ramsay of Harvard last fall, Dr. Leggett<br>
suggested that his colleagues should consider the merits of the
latter<br>
theory. "Why should we think of an electron as being in two states
at<br>
once but not a cat, when the theory is ostensibly the same in both<br>
cases?" Dr. Leggett asked.<br><br>
Dr. Ramsay said that Dr. Leggett had missed the point. How the wave<br>
function mutates is not what you calculate. "What you calculate is
the<br>
prediction of a measurement," he said.<br><br>
"If it's a cat, I can guarantee you will get that it's alive or
dead,"<br>
Dr. Ramsay said.<br><br>
David Gross, a recent Nobel winner and director of the Kavli
Institute<br>
for Theoretical Physics in Santa Barbara, leapt into the
free-for-all,<br>
saying that 80 years had not been enough time for the new concepts
to<br>
sink in. "We're just too young. We should wait until 2200 when
quantum<br>
mechanics is taught in kindergarten."<br><br>
*The Joy of Randomness*<br><br>
One of the most extreme points of view belongs to Dr. Zeilinger of<br>
Vienna, a bearded, avuncular physicist whose laboratory regularly
hosts<br>
every sort of quantum weirdness.<br><br>
In an essay recently in Nature, Dr. Zeilinger sought to find meaning
in<br>
the very randomness that plagued Einstein.<br><br>
"The discovery that individual events are irreducibly random is
probably<br>
one of the most significant findings of the 20th century," Dr.
Zeilinger<br>
wrote.<br><br>
Dr. Zeilinger suggested that reality and information are, in a deep<br>
sense, indistinguishable, a concept that Dr. Wheeler, the Princeton<br>
physicist, called "it from bit."<br><br>
In information, the basic unit is the bit, but one bit, he says, is
not<br>
enough to specify both the spin and the trajectory of a particle. So
one<br>
quality remains unknown, irreducibly random.<br><br>
As a result of the finiteness of information, he explained, the
universe<br>
is fundamentally unpredictable.<br><br>
"I suggest that this randomness of the individual event is the
strongest<br>
indication we have of a reality 'out there' existing independently
of<br>
us," Dr. Zeilinger wrote in Nature.<br><br>
He added, "Maybe Einstein would have liked this idea after
all."<br>
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