| This weeks
FactFile is taken from 'Cassell's Laws of Nature'
by James Trefil! See details of the book at Amazon.com
or Amazon.co.uk
2641/ The Andromeda Galaxy
is 2.3 million light years away.
2642/ Edwin Hubble (1889-1953)
is responsible for 'Hubble's Law' which is that the farther
away from us a Galaxy is, the faster it is receding from us.
In equation form it is v=Hr - Where v is the velocity of the
galaxy, r is its distance from us, and H is a number known
as the Hubble Constant. The currently accepted value
of the Hubble Constant is about 70km per second per megaparsec
(a megaparsec is about 3.3 million light years). This means
that a galaxy 10 megaparsecs away will be receding from us
at 700km per second, a galaxy 100 megaparsecs away will be
moving away from us at 7000km per second and so on.
2643/ Hubbles Law implies
two extraordinary things about the Universe. Firstly that
it is expanding; and secondly that it must have had a beginning
in time.
2644/ In 1995, the Institute
for Genomic Research in Rockville, Maryland, published the
first complete DNA sequence of a living organism - the bacterium
Haemophilus influenzae.
2645/ The first genome
of a eukaryotic cell ( i.e a complex cell whose DNA is housed
in a nucleus), from the yeast Saccharomyces cerevisiae was
sequenced in 1996.
2646/ In 1998, the first
DNA sequence for a multicellular organism - the flatworm Caenorhabditis
elegans - was published.
2647/ DNA in the human
genome is arranged into 24 distinct chromosomes--physically
separate molecules that range in length from about 50 million
to 250 million base pairs. A few types of major chromosomal
abnormalities, including missing or extra copies or gross
breaks and rejoinings (translocations), can be detected by
microscopic examination. Most changes in DNA, however, are
more subtle and require a closer analysis of the DNA molecule
to find perhaps single-base differences.
2648/ Each chromosome
contains many genes, the basic physical and functional units
of heredity. Genes are specific sequences of bases that encode
instructions on how to make proteins. Genes comprise only
about 2% of the human genome; the remainder consists of noncoding
regions, whose functions may include providing chromosomal
structural integrity and regulating where, when, and in what
quantity proteins are made. The human genome is estimated
to contain 30,000 to 40,000 genes.
2649/ In a matter of
about 10 to the minus 32 seconds the universe went from something
smaller than a single proton to something the size of a grapefruit
- an increase in size of 50 orders of magnitude. In comparison,
the volume of water increases by only about 10% when it freezes.
2650/ When particles
are being forged in the maelstrom of the early universe, about
100,000,000 antiparticles are created for every 100,000,001
ordinary particles. Over the next fraction of a second, the
particles and antiparticles pair up and annihilate each other
in a burst of energy - essentialy converting their mass into
radiation. When this winnowing process is over, all that remains
is the lone, leftover bit of ordinary matter. And from this
bit of cosmic refuse and its fellows, the entire known universe
is made.
2651/ Because of the
way that reproduction takes place in honeybees, each female
bee shares all of the genes of its father and half of the
genes of its mother. This means that worker bees share 75%
of their genes (as opposed to the 50% shared by similarly
related mammals). So working to sustain a sister as a queen
bee will actually get more of the individual worker's genes
into the next generation than will having daughters of her
own.
2652/ Carbohydrates are
combinations of oxygen, hydrogen and carbon in the ratio of
1:2:1. These molecules serve as the energy source for many
living systems.
2653/ There are about
4 million billion tons of nitrogen in the atmosphere, and
about 20,000 billion tons in the Earth's oceans. A very small
fraction of this - about 100 billion tons - is fixed and incorporated
into living things each year. Of the 100 billion tons of fixed
nitrogen, only about 4 billion tons is found in living plants
and animals - the rest is stored in decomposing organisms
and will eventually be returned to the atmosphere.
2654/ Lightning strikes
are actually quite common. There are about one-hundred lightning
strikes worldwide every second. That is 6000 strikes a minute.
360,000 in one hour and 8,640,000 every single day!
2655/ In the mid-twentieth
century the US Patent Office was harassed by a flood of patent
applications for perpetual motion machines - a machine that
will run forever, or, better still, provide a limitless source
of energy. The Office declared that in future any such application
would have to be accompanied by a working model. Since then
they have not been bothered with applicants.
2656/ Green plants -
what biologists call autotrophs - are the basis for
all life on our planet, at the beginning of nearly all food
chains. They convert the energy that falls on them in the
form of sunlight into energy stored in carbohydrates, most
importantly the six-carbon sugar known as glucose. This conversion
process is known as photosynthesis. Other organisms then eat
the plants to gain access to this stored energy, therby creating
the food chain that supports the global ecosystem. Photosynthesis
begins when photons from the Sun strike specific kinds of
pigment molecules, known as chlorophyll, in a leaf.
The chlorophyll is contained within the leaf cells in the
membranes of special structures known as chloroplasts (they
are what gives leaves a green colour).
2657/ Photosynthesis
is also the process that supplies the oxygen in the air we
breathe. The general reaction is:
water + carbon dioxide
+ light —> carbohydrate + oxygen
so that plants take in
the carbon dioxide that is the result of respiration and give
off oxygen as a waste product.
2658/ The word "quantum"
comes from the Latin for "so much", or "bundle".
"Mechanics" is the old-fashioned word for the science
of motion. Quantum Mechanics, then, is the study of the motion
of things which come in bundles (or, to use the modern term,
which are quantized). "Quantum" was first
used by the German physicist Max Planck to describe the interaction
of light with atoms.
2659/ The isotope
uranium-238 (92 protons, 146 neutrons) has a half-life of
about 4.5 billion years. This is the same age as the Earth,
so the entire history of our planet has been only one half-life
of this isotope (which means that half of the uranium-238
that was here when the Earth formed is still around). Uranium-238
decays into thorium-234 (90 protons, 144 neutrons) which has
a half-life of 24 days. The thorium-234 decays into palladium-234
(91 protons, 143 neutrons), which has a half-life of about
6 hours ... and so on. The process goes through about a dozen
decays until it reaches the stable isotope lead-206.
2660/ Roughly speaking,
in living things about one carbon atom in a million is carbon-14.
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facts...
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