Speed of Light Slowing Down?
What travels at 300,000 kilometers per second, is constant,
and travels faster than anything else in the galaxy? Did you
answer light? It seems like a reasonable answer, but recent
findings suggest that the speed of light may not be constantit
may be slowing down.
John Webb, a professor at the University
of New South Whales in Sydney, Australia has suggested that
the speed of light has changed. He based his suggestion on
data collected while studying a distant quasar. Quasars are
distant, high-energy objects that are hypothesized to be associated
with black holes. Quasars are so far away that the light they
produced billions of years ago is just now reaching Earth.
Spectra of astronomical objects are produced
by photons of certain wavelengths knocking electrons into
higher energy levels. Then, photons at other distinct wavelengths
are emitted and the electrons drop back to lower energy levels.
According to our law of physics today, only certain wavelengths
can alter the position of electrons in atoms, and the wavelengths
are different for each type of atom. The quasar that Webb
observed appeared to absorb a different wavelength than what
was expected. This meant that either the charge on an electron
has changed, thereby altering the energy level structure of
the atom, or the speed of light has changed.
Physicist Paul Davies of Sydney's Macquarie
University headed a team of scientists that tried to determine
which one of the laws might be the culprit. The team studied
black holes which have such a large gravitational pull that
light cannot escape them. They also applied other physical
laws such as the second law of thermodynamics, which essentially
states that you cannot get something from nothing. This law
would be violated if the charge on an electron had changed.
What implications would a change in the speed of light have
on the study of physics and the world? According to Davies,
many of the laws of the universe would be affected, such as
the theory of relativity and E = mc2.
Some scientists believe that a change
in the speed of light would only matter in the large scale
structure of the universe and its origins. For example, one
theory of the origin of the universe - the Big Bang - indicates
that early on, the edges of the universe were spread out further
than light could have traveled if the speed of light was constant.
The findings of Webb, which indicate that the speed of light
was once faster than it is now, seem to support this theory.
The question of whether or not the
speed of light is constant has been debated for several years,
with much of the information being presented in August of
2001. Research recent evidence for or against the speed of
light being constant and present the information to your class.
Include the possible affects that a change in this law would
have in how science is taught.