"The idea
that quantum/
measurement
involves an
almost magical
transformation
is now dea\ "l
\
Where does that leawourundentanding
ofhowphysicalrealityasweknowitemerges
frmnthequantumrealm?ForHansMooij,a
specialist In quantum electronics at the Delft
UDiwnltyofTechnologylnthe Netherlands,
aperiments that reveal the fine details of
measurement "will.inevitably lead to a
:reintezpretationof quantum physics~
evenifitisn'tyetclearwhatwillemerge.
For starters, says Mooij, theworkrequiles "a
complete overhaul of the Copenhagen-related
inte!pretation with collapsing wave functions"
-neither Bohr's •c1on't ask" mantra norvon
Neumann's unexplained collapse seems
needed anymon!!. The idea that measurement
involves some instantaneous, almost magical
transformation is now dead, says cabeDo.
Just add ignarance1
RemcMngthephenomenon previously known
as collapse also seems to remove the key
motivation for the many worlds interpretation
of quantum theory, which seeks to avoid the
need for collapse at the cost of proliferating
worlds. "Mypenonal view is thatauchan
interpretation is :redundant," says cannichael.
but he admits "there is always wriggle room".
ID Csrmichael's view, what seems to be
emergingissometbingnotfarremovedfrom
the objedive-collapse pictUie, with the twist
being that the random kick that forces a
quantum system to decide on its state emerges
natunllyfrom the environment, rather than
being added by hand as some putative, ad hoc
mathematialextensionof standardquantum
theory. The equation of the most popular
objec:tiv&collapse model, he says, His formally
equivalent to the version ofQ'.lT we used to
model the Yale aperiment" -wtth the random
"collapse"tennnowc:omh1gfrom the
inclusion of quantum baclc-adion.
Alguably, tbatwouldremovethecommon
objection to objective collapse-that
bolting-on a new term to the ScluOdinger
equation is makeshift. But it isn't that simple.
Forsomesupportenofthismodel, the add-on
is essential and can't be n!placed simply with
the Inscrutably random Influence of the
environment Without objective collapse,
"there is nothing really random, but only
ignorance about the enct state of the
enviro~ aaysDanielSwmntyatthe
UniversidadNadonalAut6nomaofMexico.
"And adding ignorance into the pictme can't
possibly provide a better account of the state of
affairs than not adding igncmmc:e:•
Ultimately. says Sudarsky, making the
environment the sole agent of collapse just
postpones its origin to everspanding
deflnlttonsofthesystem:ifyouaccepttbat
the entire universe can be considered one big
quantumsystemgovernedbytheScluOdinger
equation, there's nothing left to collapse it.
Given the long history of argument over the
right way to interpret quantum mechanics, it is
too much to expect the debate to be settled
easily. Theorist Roderich Tumulb at theUDiversityofTiibingeninGermanypointsout
that Ql'l'itself is agnostic aboutinterpmations,
which suggests itmay be possible to fonnulate
versions ofBohmian:mechanic:s or many
worlds that don't conflict with these new
observations. Indeed, some researchers insist
that the new results have no consequenc:es for
the various ways to understand the meaning of
quantum mechanics. For Levvaidma.u at Tel
AvivUDive:rsityinlsrael,along-termadvocate
of the many worlds idea, the Yale eqieriments
"confirm that standard quantum mechanics
and theequipmentworkwellbuthavezero
bearing onintezpretations~
Even if you aren't partial to any of the exotic
alternatives to Copenhagen. one thing at least
is certain: Bohr's insistence that the emergence
of physical reality from the quantum:malm
is something that just happens, with no
questions asked, is no longer an option. We
cannowwatchmeasmementunfold.anclwe
don't need collapse to descn'be it
The challenge now is to see ifthese new
insights an be used to replace the magic
wandofcollapsewitbafulltheoryofqwmtum
measurement. "I wish I was not retired and still
in full aperimentalnow:• says Moolj, "because
this will be extremelyemt:ing." IPhmip BaU is the author of
~Weird:Why~ng
you ff'loughtyou knew about
_ _ _ _, Quantum physics Is... dlffelent