Here are some bold statements
that should surprise no one: The legacy of physics is undeniably vast, yet often goes unnoticed.
The practice of physics today has a breadth, depth, and richness that is unparalleled in history,
yet a great many people are blind to the very existence of physics. The essence of physics retains
its elegance and profundity even as its application can render it invisible.
But wait. How can physics be invisible?
Didn't physics capture the world's attention during the 2005 World Year of Physics? Aren't television
programs and popular books about string theory, cosmology, and charismatic physicists gobbled
up by a hungry and inquisitive public? Somewhere in the world, every day, doesn't a new physics-related
story appear as a news item? Of course, of course, and of course. Despite such obvious visibility,
however, I contend that physics in its broadest sense is rarely discussed and is grossly undervalued.
Nothing I say here is new,
and much of it may already be obvious to you. I claim no special insight other than that of a deeply
interested observer of the physics community. Still, perhaps these musings will add a little twist
to your thinking; perhaps they will prod one or two of you to reconsider or refresh your own views
of physics and physicists in these very messy opening years of the 21st century.
The power of "Why"
A typical scientist brings to humanity's
table a confluence of special qualities. Foremost among those are three shared by most children
older than a few months, that the scientist somehow hangs on to and develops into a full mindset.
Those three qualities are a broad curiosity about the world and the universe; an intellectual adventurism
that takes the fright out of mental risk-taking; and a deep-seated need to understand things. That
last one needs elaboration because, in my view, it was a healthy obsession with understanding that
drove most physicists into their studies, pursuits, and profession. Curiosity can be satisfied
at many levels; adventurism can be reckless. A profound need for understanding, however, can temper
and direct both of the other drives and does so for the best of scientists. Certain people find it
very difficult to take someone else's word that "this is how it is because everyone says so" or "because
I say so" or "because this or that authority says so." A certain type of person needs—not just
thinks it would be nice, but actually needs—to find out for herself or himself why something
is the way it is. And being satisfied with the robustness of the self-discovered answer, that person
can continue confidently down the intellectually adventurous path of being curious about the
world. Those of this ilk who go into science eventually come to appreciate the robustness of scientific
results, due in no small measure to the impersonal and repeatable realities of observation and
experiment. Thus, without losing an innate skepticism, scientists can come to accept others'
scientific results as true and science gains a robust authority of its own.
Of course, that person
with a deep-seated need for understanding could be a mechanic or a legislator, a librarian or a soccer
player. Scientists have no monopoly on understanding. What sets the scientist apart is the ability
to acquire and the discipline to use a specific toolkit to examine the natural, physical world in
a rational, orderly way and thereby to discover something about what makes the world tick.
In the particular case
of the physicist, the tools in the kit are arguably some of the most sophisticated ones available
to humankind, including an impressive array of deep physical concepts and principles, a multitude
of advanced mathematical and computational techniques, an ability to creatively use—and
invent—relevant instruments, and a facility to reason analytically in a carefully logical
progression. With such tools available, a measure of understanding of the physical world is certain.
And the occasional flash of intuitive insight can be capitalized on rigorously and parlayed with
some confidence into lasting results.
The physicist uses these
tools in various combinations at various times to solve a multitude of problems—from mundane
to esoteric, from technological to hypothetical, from essential to superfluous. With not only
a healthy need to understand both the problem at hand and the possible solutions, but also an active
intellectual adventurism, the physicist brings a very large toolkit to bear on that age-old question
of "Why?" and its cousin "What if?" This, in my view, sums up the value of the physicist in today's
world.
What is physics anyway?
But what is it that physicists actually
do? What problems do they tackle? Just how do we think about this science that we call physics? Such
questions are the subject of the rest of my musings here.
Readers interested in
the history of physics—or of science or of natural philosophy—should turn elsewhere.
Nor will I mention, except here in passing, the roots of engineering as practical applications
of newly found bodies of knowledge. Instead, let's look at some snapshots of physics as we find it
today.
Most current dictionaries
capture physics's essence almost trivially with words along the lines of "a science that deals
with matter and energy and their interactions." I contend that most people have no clue as to the
generality inherent in that definition. Rather, they assume that if it's physics it must deal with
only the most fundamental notions of matter and energy, notions connected with particle accelerators
or unified forces or the origin and fate of the universe. Physics certainly encompasses those and
many similarly fundamental endeavors; indeed a great many students who are drawn to physics are
excited and energized by just such notions, by the opportunity to understand and maybe even contribute
at the deepest level to humankind's knowledge of the universe.
But I contend that that
popular perception of physics is self-limiting; as such it is misleading and does us a disservice.
Thanks to the sophistication and generality of its toolkit, physics deals comfortably with energy
and matter of all kinds, and all kinds of interactions between them, in all kinds of environments.
Metallurgy, hearing aids, sailboat hulls, and archaeology fall as much within the purview of physicists
as do galaxies, semiconductors, fiber optics, and plasma reactors.
Working physicists—those
with a degree in the subject—are as likely to find their fulfillment outside of academia as
in it, helping to solve very messy problems in a very messy world. Data from the American Institute
of Physics show that of 4000 recent physics bachelor degree recipients in the US, only half went
on to graduate school (often but not always in physics or astronomy). Of masters degree recipients,
only 30% stayed in graduate school; 60% of PhDs remained in academia one year after getting their
degrees.1
Even of those who continue
to do research within academic physics, more choose to work in areas allied with today's and tomorrow's
technology—areas like condensed matter physics, optics and photonics, and materials physics—than
to pursue answers to eternal questions. And many working physicists have found homes in other academic
departments—including the many types of engineering, as well as acoustics, materials science,
Earth science, and even departments within medical schools.
Academic physics, and
here I'm referring to the course work aimed at future physicists rather than at the general student
population, rightly focuses on passing along the tools of physics. In fact, I suggest that a working
definition of physics can be precisely that cohesive set of tools. Then the practice of physics
becomes all that is or can be done with those tools.
Hints at the generality
of those tools can be gleaned from the segmentation of physics into traditional subfields such
as acoustics, optics, mechanics, thermodynamics, electromagnetism, atomic and nuclear physics,
condensed matter physics, particle physics, and plasma physics. But I find it curious that many
physics faculty members ignore the widespread applicability of their subject beyond academe,
perhaps because they are not themselves aware of the extent to which physics has taken on a life of
its own beyond the halls of the university.
Multiple personalities
Physics faces a serious dilemma: If
it were a person, it would suffer from a severe case of multiple-personality disorder. On the one
hand, it imparts an intricate array of tools and cultivates a precious mindset of rational exploration.
To do that, it needs and revels in its splendid academic isolation. It is to that oasis that the top
students are drawn, where they have the opportunity to learn some of nature's truths for themselves,
where the thrill of seeing or discovering something for the first time will not be diminished. We
can think of this academic training ground as the core of physics, where the tools are passed from
one generation to the next. Life within that core can be both exhilarating and highly satisfying,
even as it can challenge and at times frustrate the best of minds.
On the other hand, the unity
of that core is often obscured: Academic physics is fragmented into subdisciplines that sometimes
feel a need to vie among themselves for some perceived legitimacy in the landscape of physics. Some
have spun off into new disciplines, even new departments. So we find dedicated courses in, for example,
acoustics or fluid dynamics or heat transfer are rarely available in physics departments today;
interested students must look for them elsewhere. Thus for many, physics has come to mean that particular
collection of subfields allowed into the physics department and nothing else. This is a dysfunctional
view of physics. Given the complexity of the modern physics curriculum, subfields are both necessary
and good (see figure 1); indeed, some of the most exciting research is conducted at the intersections
of two or more subfields. But isolation—whether imposed or merely perceived—of one
or another subfield from others is neither necessary nor good.
On the third hand, the actual
practice of physics is much broader than academic pursuits alone. This is physics in the real world.
It's difficult to assess the state of non-academic physics: Do physicists there have an inferiority
complex or the opposite? Have they become apathetic to or ashamed of their origins? Have they moved
on to heights of discovery in new realms that academics can only dream of? The answers to such questions
are hard to get, because many who live there ply their trade invisibly; we don't know how to see them.
Finally, many physicists
have moved out of science and technology and have gone, with their variously sized toolkits of physics,
into other human endeavors. The nature of that group is as varied as its members.
Physics entangled
Now for my entanglement metaphor, which
plays obviously on quantum mechanics: An entangled pair of objects—photons, electrons,
whatever—can propagate and evolve together as a unit, even while moving off in different
directions, but only until one member of the entangled pair is observed. At that instant the entangled
system is destroyed and a single eigenstate is detected.
The image I wish to convey
is of two or more "things" with distinct identities coming together in such a way that a synergistic
effect of some sort ensues, yet focusing on any one of the constituent elements destroys the synergy.
The rest of my title draws a more fanciful analogy to a choreographed dance troupe or a skilled couple
on the dance floor. The smooth execution of the various maneuvers presents a picture that can be
marvelous to behold. As with entanglement, focusing on just one of the dancers can reveal that individual's
skill and talent, but the bigger effect is lost. I don't want to push the analogy too far, just far
enough for you to see where my musings are headed.
Consider the case of Bose–Einstein
condensates (figure 2), existing at the intersection of atomic, condensed matter, and statistical
physics, belonging to all those fields and to none of them alone. In addition, BECs could not have
been produced, let alone studied, without the tools of optical physics, without manipulating
electric and magnetic fields, without understanding gas and fluid dynamics, or without innovations
in low-temperature physics. The experts will no doubt tell me what else I failed to mention. The
point is that BEC research depends critically on the synergistic entanglement of all these sometimes
separate fields of study. Take the contributions of one away and the program to make BECs collapses.
It's more than interdisciplinary physics coming together to solve a problem. It's a deep entanglement
of fields that gives rise to something qualitatively different, the emergence of an entirely new
field.
Science splintered and sintered
There is no shortage of examples of physics
entangled with itself, from soft condensed matter to plasma astrophysics. You no doubt have your
own favorites. Thus, even as the core of physics might get obscured by an academic splintering into
subfields, that powerful core allows physicists to continue to explore new connections and thereby
sinter elements of subfields back together in new ways.
The same holds for all of
science. Today, not a single branch of science remains isolated; at a minimim, the branches borrow
ideas and techniques from each other. Thus, for example, knowledge of botany is needed to identify
pollen found in radioactive-isotope-dated sedimentary cores drilled from the ocean's floor
to study Earth's ancient climate. To be sure, each branch of science and engineering—physics,
chemistry, biology, geology, hydraulics, oceanography, and the rest—has its own core from
which it draws its identity and which gets imparted to students. But Science with a capital S
is reaching adulthood as it must: Nature does not easily give up her answers to today's complex questions.
That we carve her up into separate disciplines is a demonstration not of her essential nature but
of our human limitations.
Such entanglements have
been with us since the days of the natural philosopher. But the current scale and number of multidisciplinary
projects is unprecedented.
Since the 2001 federal
budget, the poster child for multidisciplinary efforts in the US has been the National Nanotechnology
Initiative. With research funding in 13 federal agencies, the NNI "plays a key role in fostering
cross-disciplinary networks and partnerships."2 In November 2006 the NNI website
offered the following as some recent achievements in nanotechnology:
Use
of the bright fluorescence of semiconductor nanocrystals (quantum dots) for dynamic angiography
in capillaries hundreds of micrometers below the skin of living mice—about twice the depth
of conventional angiographic materials and obtained with one-fifth the irradiation power.
Nanoelectromechanical
sensors that can detect and identify a single molecule of a chemical warfare agent; an essential
step toward realizing practical field sensors.
Nanocomposite
energetic materials for propellants and explosives that have more than twice the energy output
of typical high explosives.
Prototype
data-storage devices based on molecular electronics, with data densities more than 100 times
those of today's highest-density commercial devices.
Field
demonstration that iron nanoparticles can remove up to 96% of a major contaminant (trichloroethylene)
from groundwater at an industrial site.
The NNI is just one multidisciplinary
research effort in the US. The NSF currently has 53 active "crosscutting and NSF-wide" funding
opportunities. A typical example is the Materials Research Science and Engineering Centers program.
The first MRSECs were established at 11 universities in 1994; today there are 29. According to the
NSF, each MRSEC is to "undertake materials research of a scope and complexity that would not be feasible
under traditional funding of individual research projects" and must take "an interactive, interdisciplinary
approach to materials research."3 Even a small MRSEC can have nearly a dozen participating
faculty members representing four or more departments.
Multidisciplinary programs
are now commonplace, necessitated by the complexity of the problems tackled and the recognition
that no single discipline, no matter how rapidly advancing or sophisticated, is adequate to the
task. The problems cover aspects of vital issues of the day like energy supply and delivery, climate
and environmental change, and technological innovation. What's more, the programs of individual
nations are often entangled with each other in our globalized world. One of the earliest may have
been CERN, the European particle-physics center. (See I. I. Rabi and the Birth of CERN,
by John Krige, PHYSICS TODAY, September 2004, page 44.)
Within any one of those
multidisciplinary and globalized efforts, physics may or may not play an explicit role. When it
does, it is but one entangled element that calls for certain personality traits in the physicists
involved: Give and take is essential to work effectively with others, and humility is needed to
learn from them. Even when not explicitly identified, physics is never far from any scientific
endeavor. One is hard pressed to find a multidisciplinary effort that makes no use of the tools and
instruments of physics, even if the roots of those tools and instruments are lost to the participants.
Impressive as the government-funded
programs are, in a sense they just mimic what the private sector has done for well over a century—entangle
people and tools and ideas from different backgrounds to synergistically create innovative new
products and drive economic growth.
Dancing with the world
I recently went to a conference attended
by users of a particular commercial software package developed to model physical systems. The
software allowed users to exploit various pieces of physical science—electromagnetics,
acoustics, structural mechanics, chemical reactions, properties of materials, and others—either
separately or in concert. The very existence of such a package is testimony to the entanglement
of science needed to address real-world problems.
On one side of me at dinner
sat a fellow whose job is to optimize the use of equipment and machinery for the manufacture of polymer-based
diapers; he works to achieve high throughput without tearing, melting, or otherwise damaging
the product, while minimizing waste. His employer is a large corporation well known to American
householders; his background is physics. Sitting on my other side was the director of research
and development for a company in upstate New York that makes electromagnetic sensors of all kinds.
One of his favorites measures the dielectric properties of asphalt to determine when it is optimally
compressed to make the best possible road surface. His background, too, is physics.
Curiously, the two physicists
see themselves as engineers. The software company sees everyone as engineers. Its product incorporates
sophisticated algorithms to solve a dizzying variety of physics-related partial differential
equations and even has "physics" in its name. Yet the physics and the physicists with whom the software
company deals are so thoroughly entangled, both with the set of problems to be solved and with the
companies and other entities working on solutions, that they have become invisible. The pervasiveness
of physics, indeed its very existence, is not always apparent even to those who work with it every
day (figure 3).
Here is an observation
that I find as relevant today as it was when made 50 years ago by Mervin Kelly, then the president of
the Bell Telephone Laboratories: "The ivory-towered existence is no more and, like it or not, the
physicist is in the midst of the fast moving currents of the day in our society." (See Kelly's article
in PHYSICS TODAY, April 1957, page 26, available online to subscribers.)
Many physicists no longer
do science at all. Enriched with their toolkit, they've moved on to other fields, perhaps law or
public service, or maybe they've become business entrepreneurs or consultants. Or any of a hundred
other possibilities. They might philosophize about religion, truth, and different ways of knowing.
Some even become editors. Those pursuits, as with physics itself, are not undertaken in isolation
but rather are the product of the practitioner's training and mindset and of the state of the world
as seen at the time. Even if the world-entangled physicists eventually lose their identity with
physics and swell the ranks of the invisible, nevertheless they remain physicists by temperament
and training, bringing a much-needed rationality to non-science-related matters that far too
often devolve into seemingly irrational behaviors.
Does it matter that a large
subculture of physics is invisible? It depends on who asks the question, on who wants the answer.
Those concerned with the essential and exhilarating work of advancing the core of physics must
answer, "Yes, it matters greatly." For them, the value of physics is in physics itself; its visibility
can never be high enough to attract all the bright students that could contribute. But for those
who are more entangled in broader pursuits, the answer is "Not necessarily." For them, the value
of physics is in what it brings to the table; the end result is what matters. That physics might not
get due credit for the part it plays is immaterial to the success of an invisible physicist. In any
case, those driven to acquire the tools of physics, driven by curiosity, intellectual adventurism,
and a compelling need to understand, will continue to make lasting contributions.
Steve Benka is the editor-in-chief of PHYSICS
TODAY.
References
1. See [LINK] for the various "One Year Later" trend reports.
2. See the website for the National Nanotechnology Initiative at [LINK].
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