Biomedical Engineering Reference
In-Depth Information
They have studied gravity, magnetism and electricity and have learned laws
which govern each. Using this knowledge, we can predict eclipses, build bridges,
and put a man on the moon. But where did these laws come from? We know how
the laws work, but what do we know about why they work? It has long been a tenet
of science that it only deals with finding laws that describe how things work so that
we can have a better world by applying them in inventions and technology. Science
has no way to discover the ultimate cause behind the laws. It makes little difference
to how your cell phone works to know whether the governing laws were written by
a Creator, or whether they are self-existent truths. We mostly just want our high-tech
devices to work, and the low-tech varieties also.
Thus, science has been
content to adopt the equations that came from some
scientist
'
s mind as explaining things
. Sir Isaac Newton discovered and articulated
some of the best known laws of all time, including his
three laws of motion
, and
law of gravity
[
1
]. Maxwell later wrote the equations of
electricity and magne-
tism
, and Schrödinger defined an
equation for quantum wave mechanics
(
applied
in NMR spectra determination
). It is rarely asked
why these equations work
, we
are just glad that someone discovered that they do indeed work. When a scientist
does ask “why” an equation works, the only answer allowed in science is to explain
it with
an even more fundamental law
. For example, Johannes Kepler
defined
three laws describing the motion of planets around the sun
. He gave no reason
why they should work, but only claimed that they do. Then Sir Isaac Newton came
up with his laws of motion and gravity, and was able to derive all of Kepler's laws
from them. Thus, Newton's appear to be
more fundamental
,
while Kepler
'
s are
now an exercise for the student
[
1
].
Many laws about
how light travels and behaves have been discovered
. At first
there was a major debate about whether light was
a particle
(like a little bullet)
that could travel through a vacuum or a wave (like sound) that required a medium
(like air) for transport.
Newton proposed that it was a particle
, because it didn't
seem to go around corners like waves do. But then a host of wave properties of light
were discovered, such as
interference
(when wave crests add), and
diffraction
(it does indeed go around corners) [
1
] (see Fig.
15.1
).
When
Maxwell
showed that light could be explained as
an electromagnetic
wave
that seemed to end the debate once and for all. Light was a wave [
1
].
