Retroactive prayer: lots of history, not much mystery, and no science
Jeffrey P Bishop and Victor J Stenger
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Many claims are made for the power of prayer, but the idea that it could work retrospectively has
caused considerable controversy. It is also beyond current scientific knowledge
Leibocivi first raised the possibility of retroactive
prayer in 2001. He reported a study that showed prayer
done for patients well after they had left the hospital,
had reduced the length of stay in hospital and duration
of fever from blood stream infections.1 In short, prayer
somehow seemed to act backward in time to shorten
patients’ stay in the hospital. The study was intended
lightheartedly to illustrate the importance of asking
research questions that fit with the scientific model of
the world.2 Olshansky and Dossey subsequently argued
that a logical explanation might be found for Leibovici’s
results.3 They point to numerous other randomised
controlled trails to support their thesis that prayer
could work at a distance of space and that it might be
plausible that prayer could act retroactively in time.We
argue that their claim is built on a confusion and lacks
a deep physical model. There is considerable fogginess
about what science means in relation to the world of
spirituality, and we wish to throw some light on the
Examining the clinical science
The latest reported clinical trial of intercessory prayer
is a three year study of 750 patients in nine hospitals
and 12 prayer groups from around the world,
including lay and monastic Christians, Sufi Muslims,
and Buddhist monks.4 Prayers were even emailed to
Jerusalem and placed in the Wailing Wall. Patients
awaiting angioplasty for coronary artery obstruction
were selected at random by computer and sent to the
12 prayer groups. The prayer groups prayed for
complete recovery of patients. The clinical trial was
double blind; neither the hospital staff nor the patients
knew who was being prayed for. The findings were
reported at the American College of Cardiology’s
second annual conference on the integration of
complementary medicine into cardiology and showed
no significant differences in the recovery and health
between the two groups. Olshansky and Dossey cite an
earlier study by this same group as supporting their
thesis. However, this also found no significant
differences between the two groups on any of the 18
outcomes.5 These results seem to conflict with the
hypothesis, not support it.
Next, consider the study by Harris et al that examined
the effects of intercessory prayer on clinical
outcomes of 466 people who were prayed for and 524
who had usual care.6 This study found a difference in
only 1 of 35 individual comparisons (P = 0.03 for that
measure) and a significant difference (weighted score
6.4 v 7.1, P = 0.04) for the primary outcome of overall
complications. No differences were found on a global
measure (Byrd score) or on length of hospital stay. The
significance for the difference on the primary outcome
was reduced (6.2 v 7.0, P = 0.05) when corrections were
made in response to letters to the editor.7
Finally, the first study that Olshansky and Dossey
reference examined the effects of distant healing,
including prayer and psychic healing, on health
outcomes over six months in patients with AIDS.8 Outcomes,
as reported in the article, were new AIDS defining
illnesses, illness severity, doctor visits, hospital
admissions, days in hospital, and mood scores. All outcomes
were marginally (but significantly) better in the
20 participants randomised to distant healing than in
the 20 control participants.
After one of the lead authors (Targ) died, however,
a reporter discovered some disturbing information
about how the study was done.9 The study was
designed to measure mortality, not AIDS related
illnesses or other cited outcomes. When the authors
broke the blinding and found no difference in mortality
(because of a low number of deaths), they scoured
the data for differences on secondary measures such as
HIV physical symptoms and quality of life. When these
analyses showed no differences between groups, they
analysed other outcomes (P values were not corrected
for these multiple comparisons). They then decided to
reblind the study and collect more data on outcomes
by conducting a chart review (targeting AIDS related
illnesses, doctors’ visits, and hospital admissions). The
chart review raises concern about bias since the two
lead authors did the chart reviews themselves and thus
failed to meet blindness criteria. The reported results
are therefore probably an artefact of sifting and resifting
of the data, unblinding and reblinding, and collecting
new data in a questionable manner after the
primary analysis until a result is found that supports
the investigators original expectations. Such a study
can hardly be set forth as exemplary.
The evidence reviewed by Olshansky and Dossey
seems weak for an even ordinary scientific claim, let
alone one that might support the extraordinary claim
that prayer works retroactively or distantly. Now we will
show that quantum physics provides no basis to expect
such a phenomenon.
The notion that human consciousness can supervene
the material principles of physics is often found in the
literature on parapsychology and complementary
medicine. Olshansky and Dossey refer to experiments
by Schmidt in which humans attempt to mentally affect
radioactive decays, which are inherently quantum
events.10 Although Schmidt claims positive results, they
are not significant and have not been replicated in the
35 years since his first experiments were reported.11 12
The claim that quantum mechanics implies that
human consciousness can control physical reality can
be traced to a misinterpretation of wave-particle duality.
12 Popular, non-technical literature often reports that
quantum mechanics shows that an object is either a
wave or a particle, depending on what you measure. If
you measure its wavelength, then it is a wave. If you
measure its position, then it is a particle. Since
measurement is an act of human consciousness, then
the implication is that thought processes in fact determine
reality. Human consciousness is also often
invoked as the mechanism for the so called collapse of
the wave function when a measurement is made. Again
we can find no basis for this in quantum theory, where
some formulations do not contain wave function
collapse or even wave functions.
The popular picture of particles as somehow also
being waves is an oversimplification used pedagogically
to explain interference and diffraction effects in
familiar terms. All experiments detect particles, and
our theories describe these particles as the “quanta” of
quantum fields and not as waves. This theoretical
description does not imply a dual reality in which one
form of reality is changed to another by the act of
measurement or human thought. Olshansky and Dossey
also suggest that modern quantum physics
provides a plausible mechanism for the backward causality
implied by retroactive prayer. Although the
results of some quantum experiments may be
interpreted as evidence for events in the future
affecting events in the past at the quantum level, no
theoretical basis exists for applying this notion on the
macroscopic scale of human experience.13 14
The human body and its parts, such as cells that are
normally considered microscopic, are too large and
contain too many particles to exhibit quantum effects
in their collective behaviour. For example, the motion
of the neurotransmitters that carry signals across
synapses and constitute part of the mechanism for our
thinking processes can be described without recourse
to quantum mechanics. Of course, the atoms in
biological systems are quantum in nature, as are the
atoms in rocks, but their collective behaviour does not
exhibit any quantum effects. Although multiple body
quantum systems, such as lasers and superconductors,
exist, proposals that the brain is somehow a quantum
device are not supported by any convincing evidence.
What is more, even if the brain were a quantum system,
that would not imply that it can break the laws of
physics any more than electrons or photons, which are
Olshansky and Dossey use the term “non-local.”1 15
Non-locality refers to the apparent faster than light
correlations exhibited between separated parts of
some quantum systems. It is interesting that the problem
of non-locality disappears when we allow
backward causality, exactly the phenomenon that
Olshansky and Dossey are attempting to exploit.12 16
They can’t have both. In any case, while non-locality
and backward causality remain controversial topics in
discussions on the philosophical foundations of quantum
mechanics, they have little to do with religion,
medicine, or parapsychology.
Health research using spirituality occurs in two types.
One type of research examines the effects that
religious or spiritual beliefs and practices have on
mental and physical health through psychological,
social, and physiological mechanisms that are well
established in the traditional social, behavioural, and
medical sciences.17–19 In this research, no appeal to
extraordinary mechanisms is made. We need apply
only ordinary psychological, social, or physiological
phenomena. Health benefits might reasonably result
from the comforting belief that a spiritual world exists,
even if it does not. Psychological and behavioural
factors have well established health effects, so it is not a
far step to accept that spiritual belief, or perhaps nonbelief,
also has health consequences.
Until recently, the scientific community has been
sceptical that religious and spiritual factors can be
quantified. Lately, however, methods have been
developed to assess religiosity and spiritual beliefs.
Some doubt remains on whether the methods are
adequate or whether what science means by religious
or spiritual beliefs is the same as what religious or spiritual
traditions mean by these beliefs.20 Yet, religiosity
and spirituality can be reasonably related to health
outcomes similar to other psychosocial factors. Within
a scientific framework, the benefits of prayer might also
be attributed to these factors.
The claims put forward by Olshansky and Dossey
are quite different from health outcomes research,
which might reasonably be related to religion or
spirituality. They argue that prayer might be used
instrumentally to bring about desired effects in the
world at a distance of space and time. The studies they
cite have very little or nothing to do with established
psychological, social, or behavioural pathways. Firstly,
the findings from human studies which Olshansky and
Dossey cite are hardly robust; in places, they are
clinically insignificant in terms of effect size and not
uncommonly steeped in controversy. Secondly, they
call on theoretical mechanisms that have, at best, a
questionable connection to medicine. Without plausible
mechanism, abundant data with strong significance
is necessary. That evidence does not exist.
Contributors and sources: JPB is an internist, philosopher, and
Episcopal priest. He wrote the introduction, clinical science section,
and conclusion. VJS is professor emeritus of physics at the
University of Hawaii and has published extensively on science
and religion. He wrote the physical mechanisms section and the
Competing interests: None declared.
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