The
great enemy of truth is very often not the lie, deliberate, contrived and
dishonest; but the myth, persistent, persuasive and unrealistic. Too often (…) we enjoy
the comfort of opinion without the discomfort of thought.
John F Kennedy
Prologue
I and two other fellow academicians had spent Doomsday [See
my earlier blog post: 60) Waiting for the world to end – What will (not) happen on
21st December 2012 (Dec 12)] on an official visit to an educational institution in Kanyakumari
district of Tamilnadu where we had spent most of the day at work indoors,
occasionally peering out and checking to see if the earth was still intact… and
it was! By all predictions of the
doomsayers mother Earth ought to have come to a cataclysmic end that day but
disappointed them all by refusing to budge even an inch.
The incident that spurred me to write this blog post happened
in a casual manner on the following day.
The conversation among a group of us somehow veered to one of the
wonders of the world, the Great Wall of China, when I made an off-the-cuff
remark that I had climbed and walked along it three years ago. One of my fellow academicians, who has an
exceptionally fine and spontaneous sense of humor, asked me if I had walked
along all of it. Realizing what he
implied (the Great Wall is well over 8,000 km long) my other fellow academician
made the remark that I had heard any number of times before, mostly from people
of similar backgrounds – that the Wall is the only physical structure on the
earth’s surface that is visible from the Moon.
I spontaneously told him that it was certainly not true and was just one
of those popular myths. Before I could
elaborate on this, the conversation suddenly changed track, but I had decided
to write about this and a random sample of several other popular myths and
misconceptions in my blog very soon.
Here is what I had promised myself.
The Great Wall from the
Moon myth
It is not very clear when and how this myth took root but it
is so widespread among all categories of people (I don’t know what fraction of
such population is Chinese) as to have become a sort of truism. People who accept it don’t ponder to question
how any construction no more than about ten meters wide, however long it may
be, and blending with the surroundings almost everywhere along its length, can
be visible to the naked eye from as far away as four hundred thousand
kilometers. The human eye is indeed a
remarkably adaptive and versatile sensor, still the small aperture of its pupil
(only about 8 mm in diameter) means a very low light gathering power, and hence
the inability to make out fine detail in distant objects.
One person to whom I put this question argued that the Wall
could have been visible from such a distance through a telescope. Apart from the obvious fact that such a
telescope has to be quite big, he was speechless when I pointed out that no
telescope has ever been placed on the Moon or in space at comparable distances,
let alone anybody looking through it.
Here is what former NASA astronaut Jeffrey Hoffman, who flew
on five space shuttle missions, says about this myth: “I have spent a lot of
time looking at the Earth from space, including numerous flights over China,
and never saw the Wall.” When I made a
casual reference to this question in one of my travelogues on China [See: 04)
China Diary Part 1 – The Great Wall & Forbidden City (Mar 10)], this is what I had to say: “Contrary to popular belief, it
is not visible to the unaided eye even from any earth
satellite, let alone from the Moon.”
Bloated Sun & Moon
– the Moon Illusion
I wonder if anyone has not
seen the Sun or the full Moon appear
much bigger at the time of sunset or sunrise (or moonset or moonrise as the
case may be) than it normally is. Since
it happens invariably if the horizon is clear, one cannot fail to have seen the
phenomenon at least during evening sunset.
From certain vantage points and depending on the nature and type of
terrestrial objects in the field of view, the sight can be spectacularly awesome,
especially the rising full Moon pockmarked with its visible features as the
following picture suggests. Not only do the
Sun and the Moon but also any stellar constellation appears to be blown out of
proportion at such times, while resuming normalcy at others. I pose this question frequently to groups of
students and teachers, many of them from elite urban institutions, when I
address them on astronomical topics. I
am yet to find anyone unaware of the phenomenon, but the overwhelming majority
of them simply don’t know why.
One very common and rather vague answer I get is that some
refraction effects are responsible. When
I probe into this deeper and ask for a detailed explanation, they get into a
hopeless tangle and end up in a mess. I
have seen two or three Ph Ds in physics do this! When I said the observation is just an
optical illusion (often called the Moon Illusion)
and had no physical basis whatsoever, at least one of them was utterly confounded
and totally unwilling to accept this explanation. He said there must be some physical reason, perhaps not yet discovered! I wonder if they are convinced even now that
there is really none.
The most common as well as the most bizarre answer I get is
that objects at the horizon are closer to the earth than when they are
elsewhere! – why else would they look
bigger? In their minds the apparent
paths of the Sun and the Moon (as well as the constellations) around the earth
are such as to bring the object closest to the earth twice a day and keep them
farther away the rest of the day. Considering how big the objects seem to
appear on the horizon, this change in distance should be quite
considerable. If so why are the mornings
and evenings not much hotter than the
rest of the day? This reasoning not only
runs counter to all common sense but also contradicts all observational
evidence. Within a span of about 6 hours
between high noon and sunset, the Earth would have hardly changed its distance
from the Sun as astronomical measurements show. Such changes are noticeable only over a period
of months or at least weeks and even then not significant enough to explain the
observations.
How can we show that this whole phenomenon is an illusion,
just a trick played on our minds? The
best way would be to take pictures of the Sun (through a small telescope using
safe filters) or the full Moon with a camera at regular intervals over several hours
without changing the instrumental settings other than exposure times. A composite picture will show a series of
images whose size remains exactly the same all through. Can there be anything more convincing? Here is such a picture:
Once we realize that there is no physical basis for the ‘Moon
Illusion’ the explanation is outside the realm of traditional science and has
to look into psychological factors, especially those related to human
perception. I shall only refer readers
to a lengthy article on this phenomenon discussed at: http://www.lhup.edu/~dsimanek/3d/moonillu.htm
Hot summers and cool
winters
As everyone has experienced, summer days are significantly
hotter than winter days almost anywhere on earth. Why is this so? Very simple, according to most people! The Sun gets closer to the earth in summer
than in winter. This is simply not true
and often it is just the opposite. For
example, even as I write these sentences the Sun is at one of its closest
approaches to the earth and still the whole of north India is shivering! So it has hardly anything to do with the
distance between the two objects. The
real reason is that because the earth’s axis of rotation is inclined at an angle
of 23.5 degrees to the ecliptic (plane of the apparent path of the earth around
the Sun), any point on the northern hemisphere of the earth receives sunlight
at a steeper angle than a similar point in the southern hemisphere and
therefore the overall energy density of solar radiation is significantly lower
as the following illustration shows:
The Big Myth about the
Big Temple
After reading my travelogue on the Big Temple of Thanjavur
[See: 56) The Big Temple of Thanjavur a glorious heritage –
Personal Photo Album Part 17 (Sep 12)] one of my regular readers appeared to have been surprised
that I had made no reference to the widely popular and glaringly unscientific
myth that the shadow of the great pyramidal temple tower (vimanam) never falls on the ground. Referring to this myth in a
newspaper story at http://www.hindu.com/lf/2004/03/30/stories/2004033001340200.htm, a research scholar wrote, “It is a falsehood repeatedly told to students, historians, tourists and
all visiting the temple, which has been declared as world heritage by the
United Nations Educational, Scientific and Scientific Organization''. To prove the obvious fallacy of this he has
published a photograph showing a shadow of the structure on the ground. The moot question is does such an outrageous
claim, flying in the face of all common sense, require any kind of contradictory
‘proof’ at all, even a photographic one.
How can anyone even entertain such a claim? If there is any object standing on the ground
under a bright Sun, how can there be no shadow of it cast on the ground? I don’t know of any law of nature that
exempts any temple structure from casting shadows on the ground. It is almost as absurd as saying that the
temple tower is invisible for that is the only way it cannot cast a shadow.
Myths and irrational beliefs associated with temples are so
numerous and so widespread that they merit a separate psychological study. I shall not attempt it here even in respect
of this big myth about the Big Temple of Thanjavur.
When Lightning Strikes
Among natural phenomena, lightning is both amazingly
beautiful to watch and deadly dangerous to experience. It is a massive discharge of high voltage
electricity in the atmosphere and can cause serious physical injury or death if
one is caught unprotected during thunderstorms that are often accompanied by
lightning strikes of varying severity. Travelers
outdoors in their cars or other vehicles often tend to rush out instinctively
towards covered places or large trees for protection. This is the result of a misconception that
outdoor structures provide a better protection than inside a vehicle like a
car. In actual fact the greatest
protection they get is by staying put inside their vehicles with all doors
closed. This is because of a well-known
property of electric charges discovered by the great nineteenth century British
scientist Michael Faraday.
Being inside a car during a lightning strike is like being
inside a fully enclosed protective metal cage called the Faraday cage. The
electrical charges induced by the lightning on the cage are confined to the
metal surface and flow around it and then into the ground without penetrating
inside. The occupants are perfectly safe
even if what they see outside may be highly unnerving.
Seeking protection under a tree may be inviting danger since
the generally damp trees are good conductors of electricity, with no Faraday cage like safety offered. Sometimes the
trees themselves may catch fire because of intense heating of its parts.
Venus, Earth Satellites
and UFOs
Human fascination for UFOs (Unidentified Flying Objects) is
so strong that anything moving in the sky often ignites interest and promptly gets
dubbed as a UFO if the viewer has no idea of what it is. At times planet Venus is seen as a
spectacularly bright evening object low on the evening horizon and people
unaware of its identity frequently mistake it for a UFO, often speak of it as
such and some media even report it as such.
The sight can be eerie (and even scary for believers in UFOs) if a
crescent Moon is also visible nearby as is the case sometimes (see picture
below). The most preferred
interpretation is that it is an alien ship on a visit to planet earth. Some decades ago one such newspaper report
caused so much stir that it forced the attention of the Indian meteorological
service who promptly promised a thorough investigation! I do not know if the
investigators discovered the simple truth and publicized it.
Nowadays one can often see in the post sunset sky a number of
bright man-made earth satellites in rapid motion and act as UFO ‘candidates’
among the uninitiated. The huge
International Space Station (ISS) and the rather frequent ‘Iridium flares’
(these are communication satellites, about 80 of them in low earth orbit,
flaring up momentarily as a very bright flash of light when its reflective
solar panel comes in the line of sight of the observer) are nowadays seen so
frequently that they have even lost some of their sheen as possible alien UFOs.
Incidentally, one can obtain advance
information about the visibility and path/location of such man-made earth
satellites at any place on earth from popular websites such as http://www.heavens-above.com/.
Mobile myths
Nowadays it is rare to find anybody without a mobile phone
handset that gives the power of instant communication with anyone
anywhere. With such widespread use, it
is no wonder that the mobile handset is at the heart (no pun intended) of
numerous myths and misconceptions associated with the fact that they receive or
transmit electromagnetic radiation at very low frequencies. Let me refer to just two of them here – that
their use can cause cancer or affect the heart, the latter when kept in shirt
pockets for too long. There is no
evidence for either though such evidence has been available only for the short
duration of time the devices have been in use since their invention. While any such prognosis has to wait years
and even decades of regular future use, any possibility of harmful consequences
will have to be weighed in the light of the following facts.
The human body is being bombarded all the time by a variety
of electromagnetic radiations, ranging from the very energetic and harmful
ultraviolet rays to low-energy harmless radio waves that we use for all types
of communication all the time. Though
an ozone layer high above the earth’s atmosphere provides a blanket of safety
against the ionizing ultraviolet radiation, there is always some residual high
energy radiation (and cosmic ray particles) from which the body is never
immune. Compared to the total energy the
human body absorbs relentlessly from such sources the additional contribution
from mobile transmitters and receivers is negligibly small and cannot possibly
pose any significant additional long-range threat to the human body.
Navagrahas (Nine Planets)
Despite all that we know about our (heliocentric) planetary
system in modern Astronomy, the extraordinary and widespread myth persists
about the existence of navagrahas
(nine planets) that are supposed to influence human affairs in mysterious ways depending
on their relative positions, especially at the time of birth of the person
concerned. These nine planets are not the ones we are familiar with in
Astronomy – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and
Pluto, the last of which was incidentally demoted some years ago from the list
of planets for perfectly sensible scientific reasons. These Navagrahas
know from ancient Indian Vedic times are: Surya
(Sun), Chandra (Moon), Mangala (Mars), Budha (Mercury), Brihaspati
(Jupiter), Shukra (Venus), Shani (Saturn), Rahu and Ketu. While the first two are indeed objects of the
solar system, though not planets, the last two are not even material objects of
any kind; they are just imaginary points
in space - the points of
intersection of the paths of the Sun and the Moon as they move around the
celestial sphere (see figure below).
Compounding the myth of the navagrahas is the utterly irrational and widely practiced belief
that a certain period of time each day, related in some ways to the concept of Rahu, is inauspicious for performance of
any important human activity. This is one
of the most astoundingly superstitious and blind beliefs prevalent in the
Indian society, and large numbers of people from all walks of life refuse to do
anything that they consider important during this period called rahukaalam. I once had the mortification of having to
wait a considerable time for the staff and students of a reputed academic
institution to turn up for the day’s work because their institution’s head
didn’t want my visit to begin during such a rahukaalam!
On another similar occasion when I was being hurried to begin my work before
the dreaded rahukaalam set in, I
deliberately stalled the proceedings and started work only after the period
began, much to the chagrin of the man in charge! It didn’t make any difference to the eventual
outcome of my assignment.
Epilogue
Some years ago I was a resource person at a short term course
for teachers and used to engage the pre-lunch session each day, followed by
joining the participants for lunch arranged at the venue. A long duration partial
eclipse of the Sun took place on one of those days and, at the organizers’
request, I had made a multimedia presentation relating to the event and showed
the eclipse itself live with a small telescope I had taken along. Curiously, I observed that some of the
participants were not interested in watching the eclipse show though they had
all attended my classroom presentation. It
was only at the usual lunch time I realized why. No lunch was being served that day because,
as the organizers explained to me, most of the participants had indicated that
they would not be eating lunch that day!
They were dutifully obeying centuries of superstitious tradition that
forbade them from eating anything during an eclipse. I had no doubt they would all take a bath
after the eclipse ended and eat anything only thereafter.
Well,
even after this experience, my belief in the long-term transformative potential
of education is neither a myth nor a misconception.
