| 2761/
According to the classical theory of Diffraction,
light from any distant object, when passed through a circular
aperture, will produce an image consisting of a series of
light and dark rings surrounding a bright central spot - what
is called a diffraction pattern.
2762/ Radiometric dating
of the Turin Shroud carried out in 1988 shows the cloth to
have been made no earlier than 1260.
2763/ Folklore has it
that Albert Einstein is supposed to have had his momentous
insight about relativity while riding on a streetcar in Bern,
Switzerland. He is supposed to have looked at a clockface
on one of the city's towers and realized that if his streetcar
were to accelerate to the speed of light, it would appear
to him that the clock had stopped - that time had ceased to
pass. This led him to one of the central insights of relativity
- the notion that different observers will see events differently
and will disagree even on such fundamentals as time and distance.
2764/ The masses of objects
increases as their velocities approach the speed of light.
At 260,000 km per second (87% of the speed of light), the
mass of an object seen by an outside observer will have doubled.
2765/ Isaac Asimov's
Three Laws of Robotics - Taken from the Handbook of Robotics
published in 2058 - 1/ A robot may not injure a human being
or, through inaction, allow a human being to come to harm
- 2/ A robot must obey the orders given it by human beings,
except where such orders would conflict with the First Law
- 3/ A robot must protect its own existence as long as such
protection does not conflict with the First or Second Law.
2766/ Sodium is an atom
that radiates primarily at a couple of wavelengths corresponding
to yellow light.
2767/ An airplane moving
at the speed of sound is said to be travelling at Mach 1.
2768/ The ratio of the
speed of light in a vacuum to the speed of light in a material
is called the refractive index of that material. The refractive
index of glass, for example, is about 1.5 (depending on the
type of glass), which makes the speed of light about a third
slower in glass than in a vacuum.
2769/ Have you ever stood
at the side of a swimming pool and noticed that your friends
legs seem very short when he's standing in the water? The
light beam that comes to your eye from your friend's foot
is bent when it leaves the water and enters the air. Consequently,
it comes to your eye at a flatter angle than it would have
done had the water not been there. Your eye traces back along
the direction of the beam and tells your brain that your friend's
feet are higher up than they actually are.
2770/ The viper's venom
is harmless as long as it does not mingle with the blood.
Courageous experimenters have tasted, swallowed it, and yet
afterward were no worse off than before.
2771/ When objects are
heated, they radiate energy. When we describe something as
'red-hot'. It is because is is hot enough to radiate visible
light, mostly in the red region of the spectrum.
2772/ The Sun has been
burning hydrogen for about 5 billion years, and has enough
hydrogen reserves in its core to keep on doing so for another
5.5 billion years or so.
2773/ Symbiosis (from
the Latin for 'living together') is the close-association
of organisms of different species. If the relationship benefits
both parties, it is called mutualism. If it benefits
one party and neither benefits nor harms the other, it is
called commensalism. If it harms one party while
benefiting the other, it is called parasitism.
2774/ An important link
in the nitrogen cycle depends on a symbiotic relationship
between plants such as legumes and soil bacteria known as
Rhizobium. These bacteria live in the roots of the plants
and have the ability to 'fix' nitrogen - that is to break
the strong bonds that bind nitrogen atoms into molecules in
the atmosphere so that the nitrogen can be incorporated in
molecules, such as ammonia, that the plant can use. In this
case the mutual benefits (mutualism) is obvious -
the roots provide a home for the bacteria, whilst the bacteria
suplly an essential nutrient for the plant.
2775/ The human gut offers
an example of commensal relationships, because it
is host to many bacteria whose presence does not harm us.
2776/ Mistletoe is a
parasite that feeds on the trees onto which it fastens,
draining nutrients from the host without providing any compensatory
benefit.
2777/ Skydivers reach
a terminal velocity of about 120 miles per hour (190 km/hr)
if they spread eagle themselves to maximise their air resistance,
but a velocity of 150 mph (240 km/hr) if they assume a head-down
position like a high-board diver about to enter the water.
2778/ Julia Roberts does
not own a TV or a land line. She does have a mobile, but she
insists that it is rarely switched on.
2779/ 2% of mobile owners
had their phones stolen last year - a theft every three minutes.
The Metropolitan Police claim that mobile thefts account for
1/3 of all street robberies in London.
2780/ In March 2003 a
study in the International Journal of Oncology suggested that
mobile phone users had a 30% increased risk of brain tumours
- mainly accoustic neuromas - which occurred close to the
ear used for mobile phone listening.
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