Although our galaxy, the Milky Way, is
truly enormous by Earthly standards, it is quite insignificant compared to the entire
Universe. It takes light about 60,000 years to flash across the Milky Way, but this is
only a brief instant compared to the it time it takes it to flash across the visible
universe, 30 billion years.
Our galaxy, of course, is only one among many billions. Studies of
large-scale structure of the universe shows that there is definite structure in the
universe as far as we can possibly observe. Galaxies; the building blocks of universe, are
not simply distributed randomly here and there, as in so many marbles in a bag, nor do
they resemble a disorganized swarm of dust particles floating aimlessly in space.
Independent of each other, but vast majority of them are organized into large orderly
collections, clusters and super clusters, consisting of thousands, moving in unison, as it
were. They are then gathered in regular patterns that look almost foam-like or sponge-like
in appearance. Latest studies of the large scale structure, both in the northern and
southern hemisphere confirm that galaxies are distributed on sheets, bubbles or filaments
with huge voids in between. These voids, as large as 400 million light years across, are
not rare but are in fact a common feature of the universe.
One of the biggest of these voids, hole in space, is the so-called
"Hole in Boots" with a volume of 10 trillion cubic light years and with hardly
any galaxy in it. To give you an idea of the vastness of this gigantic hole, it is big
enough to contain well over a billion galaxies the size of our own Milky Way.
One of the biggest of the structures is the Virgo Supercluster,
containing thousands of galaxies, including our own Local Group, which in turn includes
the Milky Way. All moving at 600 km/second toward what appears to be a vast aggregation of
matter, dubbed "Great Attractor", located 150 million light years from the Milky
Way and containing the equivalent of, tens of thousands of galaxies, more than a
quadrillion times the mass of the Sun.
Virgo Supercluster measurements now confirm that the average mass per
galaxy is several trillion solar mass and not just a 100 billion or so previously thought.
Our own Milky Way, for example, has at least 100 billion Solar sized star but weighing at
least one trillion Solar mass. The rest of the mass being invisible, the so-called Dark
matter, nature and identity of which is yet to be determined, one of the many unsolved
puzzles of Cosmology.
These numbers are stunning in a variety of ways. They show the
magnificent hierarchical structure of the Universe, as well as the enormity of the
structures and mass. They also show the vastness of the universe. As massive as these
galaxies and structures are, the universe is so vast that when visible mass of all objects
in the Universe are added up we obtain an average density of only 10^-31 gm/cm^3. An
earth-sized balloon of it would weigh no more than one flea. Of course, there is
tremendous amount of Dark matter, add all that up and we have at least a tenfold increase,
a mind boggling amount of mass of various forms, yet an Earth sized volume of it would
now, weigh about ten fleas!!
As tremendous as these numbers are we need not go into the deepest
space or farthest corner of the Universe to appreciate the Majesty and power of God and to
praise His Glory. All around us, in our bodies, wherever we look we have one of the
densest objects in the entire universe, the nucleus of the atom and we have some of the
emptiest regions (without getting too technical), anywhere in the universe, the atom
itself. The volume of a typical atom is10^15 times larger than the volume of its nucleus.
For comparison, if we enlarge the atom to the size of Empire State Building, its nucleus
would be no larger than a grain of sand at the center comprising over 99% of the weight of
the atom. So keep in mind , your body , this paper you are reading, the chair you are
sitting are all nothing but vast regions of virtually empty space surrounding an
infinitesimally small nucleus.
The proceeding also explains why, for example, a neutron star weighs so
tremendously, a tablespoon of it weighing many billions of tons. Stars with about 8-30
solar mass do not die a calm and peaceful death when they reach the end of their lives. At
that point the force of Gravity is so tremendous and the star so defenseless, that gravity
totally crushes all the atoms all the way to the nucleus leaving only the nucleus which
now consists primarily of neutrons (thus the name neutron star). This process will reduce
the size of a once mighty and giant star, many times bigger than sun, to only 10-20
kilometers.
