|
 Fundamental physics research is the genesis to which virtually
all scientific knowledge and technological advancements can be traced. Without
a robust research program designed to study the basic laws that govern how
nature operates, progress is hopeless. The microgravity research program
in fundamental physics studies these basic processes on scales ranging from
the subatomic to the systems as large as the universe itself. |
The Building Blocks of Scientific Progress
Depending on when you ask the question "What is Fundamental Physics?" you'll get a different answer. For example, in the mid 1860's James Clerk Maxwell, the famous British Physicist, deduced a series of four basic equations in electromagnetism. These are the so-called "Maxwell's Equations" which govern the fundamental behavior of electromagnetic radiation. At that time, Maxwell's research was considered "Fundamental Physics," and in fact, his work was accepted only slowly by researchers of his day, despite its simplicity, elegance, and power. Today, these same four equations are used in the design of nearly every piece of communications equipment, radar antennae, radio telescopes, cellular phones, satellite transmitters and thousands of other products. They were the first indications that light was actually an electromagnetic wave. The actual reality of such electromagnetic waves was later proven by Hertz. Maxwell's equations also hinted in the mid 1860's at the nature of the theory of relativity to be developed roughly 50 years later.
As another example, consider the "Fundamental Physics Research" of Isaac Newton, who figured out the mathematical relationship between the gravitational force felt between two objects, their masses, and their separation. His fundamental research indicated that if an object were thrown with enough velocity, it would continue to circle the Earth, without hitting the ground. In his time, the actual realization of such a feat would have been considered pure fiction. Today, we have over 700 satellites orbiting the Earth, doing just as Newton's theory predicted. We have used his fundamental research to guide men to the moon, and spacecraft to every planet in the solar-system with the exception of Pluto.
As the 20th century draws to a close, our technology is far beyond that of Maxwell's time, but the reservoir of fundamental physics knowledge is far from running dry. Our experiments today involve studies of the General Theory of Relativity, exotic states of matter called "Bose-Einstein Condensates," high resolution tests of theories of gravity, and the study of materials at extremely low temperatures. These elegant and precise experiments require highly controlled laboratory conditions free from the influence of gravity's perturbing effects, such as can be provided aboard the space shuttle.
Studying
the Fundamental Properties of Helium
Helium
is the second most abundant element in the Universe, and one of the original
elements to form in the Big-Bang, along with hydrogen and small amounts
of lithium. In fact, Helium was discovered as an element in the Sun before
its discovery on Earth. The goal of the CHeX experiment is to explore the fundamental physical
properties of helium at extremely low temperatures, where the behavior of
helium is quite different from the gas-like state that we are familiar with
when we observe it in balloons at birthday parties or in airships circling
above sporting events. The fundamental physical nature of helium - what
we're trying to understand with the CHeX experiment - plays an important
role in a phenomenal number of areas; from generating energy in stars at
high temperatures and pressures, to performing critical low-temperature
functions in the health care industry, and helping scientists study the
process of superconductivity.
At extremely low temperatures, helium will not only liquefy, but will enter into what is called the superfluid state, which is characterized by the ability of the liquid to flow virtually without the presence of friction. This unusual state of matter is noted only in liquid helium when it is cooled to nearly absolute zero, or approximately -459 degrees Fahrenheit. Among other things, the CHeX experiment will perform measurements of the specific heat, or the amount of energy required to raise one gram of the material by one degree. The emphasis will be to explore the region where liquid helium "crosses over" from its normal three dimensional behavior to the two-dimensional regime.
When liquid helium in the superfluid state is spatially confined, it enters into what scientists call the "two-dimensional regime," where a substance can exhibit behavior uniquely distinct from its three-dimensional state. Theoretical predictions have been developed that describe the behavior of liquid helium's heat capacity in a temperature range around its superfluid, or lambda, transition when confined to a two-dimensional state.
To
date, the experimental results are in apparent conflict with these predictions,
however the accuracy of the experimental data is not quite sufficient to
provide a detailed check of the theory. An experiment of higher accuracy
- like CHeX - should be able to clarify the apparent conflict.
CHeX is an experiment that builds on our fundamental physical knowledge obtained from previous experimentation aboard the space shuttle. The Lambda-Point Experiment (LPE), which was performed on the space shuttle in 1992, demonstrated that high-accuracy heat capacity data for liquid helium at its lambda transition could indeed be made. Temperature measurements with a resolution of around one nanokelvin (one-billionth of a degree) were obtained. LPE took advantage of the microgravity environment of the shuttle to overcome hydrostatic pressure effects - pressures generated within the liquid helium due to the weight of the liquid helium itself - that distort temperature measurements made on Earth. CHeX will also make use of this environment to obtain data with an accuracy not available in Earth-based experiments.
Go to the
USMP-4 Science Home Page
Authors: Dr.
John Horack
Curator: Linda
Porter
NASA Official: Dr. Greg
Wilson