The Laboratory Environment
For some reason, the idea of an astronomer working in the daytime
seems a bit strange. I mean, after all, isn't the business of
astronomy to look at stars, and don't stars only come out at
night? Even though the answers to both of these questions are a
resounding 'Yes!", thanks to such inventions as photography and
computers, the practice of astronomy is no longer restricted to
nighttime observations. In astronomy, a photograph of the sky
really can be worth a thousand words, but by and large, those
words are written in the privacy of your office in broad
daylight, and not on a cold, dark mountain.
Astronomy is a rather complex web of many activities which change
as your research evolves. If I were to try to describe this
chain of events, I would be tempted to say that it consists of
about eight stages. But in reality, you are actually quite
oblivious to this kind of division of labor because the various
stages may often occur at the same time and may not always be
taken in chronological order. You usually begin a program of
research by reading lots of research papers in order to come up
with a list of ideas, issues, or objects you want to study. As
you mature as an astronomer, ideas come more and more of their
own volition. With your idea in mind, you then obtain the data
or assemble the equations needed to form a mathematical model.
The third stage involves refining the data to obtain a collection
of physical quantities such as the intensity of the radiation
measurable at a particular point on a distant luminous cloud; or
it might include writing and debugging computer programs to
perform the calculations required by your mathematical model.
Having done this, you need to take a giant step into the realm of
abstract ideas, deriving new quantities from your 'raw' data or
computer model. This is usually the point at which controversies
and disagreements can creep in because you have to advocate some
particular scheme for going from the raw data to the extraction
of meaningful 'hidden' quantities such as mass, luminosity,
temperature, or magnetic field strength. I'm going to call them
hidden quantities because they are not directly measurable with a
ruler or stop watch, but have to be logically inferred from the
direct observations.
If you look a little bit closer at the make-up of a program of
research, the hardest part of the whole process is, believe it or
not, finding a new problem to work on that is both interesting to
you, of significance astronomically, and within your ability to
carry to fruition. By the word 'problem' I mean quite a lot of
different things. Usually a problem can take the form of a
question like " What is the optical appearance of the object
associated with the radio source 3C 326.1?" or " What are the
dynamical stages leading to a carbon detonation supernova?" There
are an unlimited number of questions one might think to ask, but
the answers to many of them are either beyond our technology to
gather data, or else trivial and irrelevant. A professional
learns through experience how to ask profitable questions.
Given that you are proficient in a particular area, your choice
of a research topic can involve something as simple as exercising
a whim, or as complex as a systematic study of a class of
objects. Sometimes the data itself can suggest an exciting avenue
of work for you to pursue. Modern astronomical databases can
consist of specially made photographs of selected regions of the
sky, magnetic tapes filled with measurements of the light levels
detected by your instrument as it scanned across the sky, or
perhaps a collection of spectrograms of peculiar stars or
galaxies.
A good deal of the time we spend at work entails meticulously
combing though the data and extracting from it more meaningful
information about the physical properties of an object. This is
detective work of the highest order because you don't have a
smoking gun, a corpse, or even a trail of bad checks to examine.
What you do have are, say, an assortment of photographs of the
scene of the crime, the shoe size of one of the assailants, and
perhaps a few eyewitness accounts of what happened. From this
indirect information, you try to deduce in what city the crime
occurred, the type of crime committed, and the identities of the
people involved. Although for detective work in the human sphere
it's almost impossible to learn all of this information from the
few data provided, we 'celestial detectives' are, luckily, much
better off. To offset the dearth of clues, we have the regularity
of the physical laws of nature which can form a sturdy bridge
between scanty evidence and interpretation.
Once you have decided on a particular problem to study, and have
obtained the necessary observations, you then have to put your
data in a form suitable for extracting the information you need.
In particular, you have to thoroughly understand the relationship
between the data you have and the physical attributes of the
phenomenon you are trying to study. For example, if you are using
an infrared device called a bolometer, you have to be able to
relate the output voltage level from the bolometer, suitably
amplified, to the amount of infrared radiation that it absorbed
from the distant object you were studying. Just like a
thermometer, a bolometer heats up in proportion to the amount of
radiation it absorbs. This causes a change in the current passing
through it. By measuring the resulting voltage change, you can
work backwards to find out how much radiation struck the device
and from this, just how bright the object in the sky is. To go
from a voltage scale to an energy scale meaningful to astronomers
is analogous to going from the volume of the mercury in a
thermometer to a temperature scale -- only the latter would be of
interest to you on a hot day! In practical terms, this means
converting your data from units of voltage (volts) to units of
irradiance ( Watts per square meter per Hertz per steradian). It
is only the amount of irradiance you have detected that tells you
something about the astronomical object. To convert from one
system of measure to another is not quite as difficult to do as
it might seem since you can determine from lab experiments how
much voltage corresponds to how much irradiance.
Astronomy is, of course, more than just doing basic
research in your office or laboratory. In addition to all these
activities, you have weekly or monthly colloquia and seminars to
attend, travel arrangements to make for your next observing run,
or observing proposals to submit to get data on a new area of
research. There may also be other diversions like keeping up
with current research in other areas of science that interest
you, or even working out at the gym during lunchtime three days a
week. Well, there you have it: Some of the nuts and bolts of
what astronomers do on a daily basis. Sounds pretty cut and dry
doesn't it? I bet for some of you it even reinforces your image
of astronomers that they are rather colorless individuals in
white coats mindlessly and slavishly persuing the answers to some
equations. No creative people here, right? No Shakespeare's, Da
Vincis, Beethovens or Nurieves among them, right? You might even
feel that Walt Whitman's sentiments about astronomers are pretty
much on the mark. Walt Whitman lived at a time when astronomy
was a young science involved in the rather mechanical but
necessary chores of classifying phenomena and measuring them. In
Whitman's poem, "When I Heard the Learned Astronomer" he wrote,
"When I heard the learned astronomer When the proofs, the figures
were ranged in columns before me, When I was shown the charts and
diagrams, to add, divide and measure them, When I sitting heard
the astronomer where he lectured with much applause in the
lecture-room, How soon unaccountable I became tired and sick Till
rising and gliding out I wandered off by myself In the mystical
moist night air, and from time to time, Looked up in perfect
silence at the stars."
Were Whitman alive today, it's certain that not only would he
have encountered much more skilled lecturers in popularizing
astronomy (I hope!), but the content of those very lectures would
have astounded him. Today's issues are far more mature and
sublime than those of the 19th century. Even the mechanistic,
gear and clockwork physics of that age have been replaced by the
'free will' indeterminacy of 20th century quantum mechanics.
Invisible but potent 'fields of force and matter' now steer and
define all known elements of physical reality, and the 'mystical
moist night air' is no less so for our greater understanding of
it.