SUMMER 2011

It’s All Relative
Our Expanding Universe: Part 2
by Jeff Burkett, Mathematics & Natural Sciences Instructor
P
erhaps the single most important consequence of the European
Renaissance was that great thinkers like Copernicus, Galileo,
and Newton shattered previous notions of a geocentric universe.
Science, religion, and philosophy were thrown into upheaval by
the new reality that Earth was not the central object of creation. This was a
mere prelude, however, to the dawn of our understanding of the true vastness
of the cosmos.
As early as approximately 400BC, Democritus had proposed that stars were
actually distant suns, and in 1600 Giordano Bruno was burned at the stake
for suggesting this heretical idea. Nevertheless, Isaac Newton, and others,
soon adopted the notion. Then, in 1838, Friedrich Bessel successfully
measured the first interstellar distance using the technique of trigonometric
parallax 1 . He calculated the star 61 Cygni to be about 10.4 light years 2
distant, an error of only about nine percent from the modern accepted value
of 11.4 light years. Other measurements soon followed, and it was quickly
established that Alpha Centauri was our closest stellar neighbor, 4.2 light
years away. That’s roughly 24,000,000,000,000 (24 trillion) miles!
circumference of the actual Earth 3 . As incomprehensible as these distances
may have seemed to early scientists, the story became even stranger.
In the 1920’s, Edwin Hubble proved that not only were the billions of visible
stars in our night sky, all part of the same Milky Way galaxy, but also that the
Milky Way itself was only one of billions of galaxies in the universe. More
astoundingly, all of these galaxies seemed to be rushing out at incredible
speed from a singular point in space: the universe itself was expanding!
Later, in 1949, Fred Hoyle coined the term “Big Bang” to describe this
phenomenon. The term stuck, and after nearly a century of observation,
experiment, and accumulated evidence, the Big Bang theory 4 remains the
most complete and comprehensive explanation of the early development of
the known universe.
Such vast distances defy human comprehension and are best understood
through analogy. If the Earth were represented by a standard-size marble,
the moon would be the size of a BB placed 17 inches away; the sun would
be represented by a sphere 5 feet in diameter, placed 180 yards (about
two football fields) from our model Earth. On this same scale, Alpha
Centauri would be about 27,000 miles distant, or slightly further than the
1. For an explanation of this technique, take my physics class or
stop by my office.
2. Note that the modern unit of light years is used here for
convenience. Accurate measurements of the speed of light
would not be realized until the following century.
3. This model is based on that of Dr. James Pierce, Professor of Astronomy at
Minnesota State University, Mankato.
4. It is worth noting that the Big Bang theory deals with the behavior of the
universe after its moment of inception. It is not a ‘creation’ theory and does not
attempt to explain the actual causation of the universe.