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Standing an
egg on its head – only on the spring equinox?
This is the
kind of logic question, which needs to be asked carefully: can you stand an egg
on its head on the vernal equinox? Yes, given the proper practice. Can you
stand the egg on its head on any other day of the year? Yes, given the proper
practice.
There are
some urban myths and stories that can
stand a little digging, but this is not one of them in my not very humble
opinion. The equinox and by extension the seasons all depend on the tilt of the
earth, relative to the sun, twice a year, (spring and autumn equinoxes) the
tilt of the Earth on its axis is perpendicular to the sun and so equal
distribution of day and night.
Of course historically
the vernal equinox has had a great cultural significance for many people’s,
being of equal length day and night , the days following would be longer, it is
a time of rebirth, of new light , of new beginnings. It is likely that eggs
have played an important part in these celebrations over different cultures and
generations. We only have to look at the Easter Egg traditions which now
accompany the Easter festival. It is thought that the traditions regarding eggs
predate the Christian festival, there are of course Christian traditions which
have grown up associated with eggs, such as the analogue between Christ’s birth out of the Sacred Womb and the painting
of the eggs symbolises using a food to
celebrate to celebrate which was banned during the Lenten period.
It is not
beyond logic that the standing at the spring equinox story would gain momentum,
after all it is the time of year most associated with eggs. There is a suggestion that the Chinese first
started the association of egg standing and Spring equinox (note; there is some discussion around this as the
Chinese festival upon which the observation occurs is actually a few weeks away
from the vernal equinox, Also by-and-large, Chinese festivals follow the lunar calendar). This period is seen
as a time of balance, equal day and night dark and light. The egg with its life
giving associations was in balance when stood, this is a good omen for the year
ahead.
What are
the factors which could influence the standing of an egg?
Gravity, we
know that the lower the centre of gravity, the more stable an item is (usually),
so using the flatter end can help this.
There is nothing in the spring equinox to alter the gravitational pull
on the egg. The egg is one of two bodies and as Newton wrote (translated): Every point mass attracts every single other
point mass by a force pointing along the line intersecting both points. The
force is proportional to the product of the two masses and inversely proportional
to the square of the distance between
them[1].
so all you need to do is have the intersection line at the right angle relative
to the egg and planet. The actual angle of the planet is not of any consequence
because the centre of gravity in the same (give or take, but not enough to
influence the egg). Slight aside: again using logic, if the Earth’s angle had
an influence, then surely the geo-location used to attempt the egg standing
would be crucial. If the Earths angle is so important, then surely the only
place to do it would be at the appropriate north pole (true north as against
the other 5 or so north poles)[2],
after all if done anywhere else is that angle off set? If there is an
offsetting, can that be built in to the equation (so to speak) for when the earth is not
located at the vernal equinox.
This of
course brings me to the one of the basic objections to the theory: why is it
only on the vernal equinox, there is nothing gravitationally different between
the two. Not only that but are we saying that the premise does not hold in the opposite
hemisphere? Again I can see no difference between either hemisphere. Given that
the Earth is more-or-less a sphere – we will ignore the slight flattening
effect between the poles – should there be a influence on where we are East or
West, left or right. We need to remember markers such as the Greenwich meridian
are human constructs, the meridian could very easily have been Paris, save for
political influence.
The
difficulty of standing an egg is, as we know, balance. Let’s have a look at
that. The oval egg is made up of the thick white of the egg, in which sits the
dense yoke. This raises the centre of gravity. Also the yoke is often non-symmetrical
in its location or resting in the egg. The steady hand is needed to “feel-for”
where the actual centre of gravity is for a specific egg. One of the
areas that have been looked at, is the nature of the shell. An egg with a
rougher texture to its shell will grip a surface better than a smooth egg and
so will be more likely to remain in position. Which end you try to stand also
influences. As mentioned above, balancing on the narrow end (pole) of the egg is
what takes the greatest skill given the limit surface area with which to work.
Given the
relatively small surface areas involved (the end tip) and the corresponding
points on the object the egg is standing on, it is easy to see how an outside
influence like a vibration, air current or other factor could prevent standing,
but a stable environment with no drafts will quickly overcome this.
Oh and
by-the-way, for any of you wise-asses, we are talking about a raw egg. To show
the complexity of egg balancing, take two eggs one hard boiled, the other raw. Spin
both and then hold to stop, take your hand away and the boiled on will fall
over while the raw egg will likely restart spinning (if you did it right)
because the inside of the egg did not stop and the inertia of its spin starts
the process again for the whole egg. Even
better, take the hard-boiled egg, lay it on its side and start it spinning as
quickly as you can, once the egg is rotating quickly enough it will rise up and
rotate like a spinning top. This seems counter intuitive but Keith Muffatt and Yutake Shimomura have studied
this area and explain that it’s because of friction. Friction destabalises the spinning
of the egg and causes a shift in position. Essentially an amount of the kinetic
energy generated by the spinis converted to potential energy, this is the energy
that is stored in an object that has a distance to fall. For a few seconds the
egg when standing on end has more potential energy and less kinetic energy, at
least for a few seconds.[3]
[1] · - Proposition 75, Theorem 35: p.956 - I.Bernard Cohen and
Anne Whitman, translators: Isaac Newton, The Principia: Mathematical Principles
of Natural Philosophy. Preceded by A Guide to Newton's Principia, by
I.Bernard Cohen. University of California Press 1999 ISBN
0-520-08816-6 ISBN
0-520-08817-4
[2] http://www.scientificamerican.com/article/the-earth-has-more-than-one-north-pole/
[3]http://cel.webofknowledge.com/InboundService.do?product=CEL&SID=Z1ElMR2LEuwatdYo3Q6&UT=000174607800032&SrcApp=Nature&action=retrieve&Init=Yes&Func=Frame&SrcAuth=Nature&customersID=Nature&IsProductCode=Yes&mode=FullRecord
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