A number of physicists in the 20th Century promoted the idea that beauty is a useful criterion of truth in fundamental physics? Also, intuition is sometimes mentioned as a good guiding light in research. Do you agree?
Sir Richard Feynman once said, “You can always recognize the truth by its beauty and
simplicity”. ‘Feynman diagrams’ bear witness to this statement as they greatly simplify the
representation of otherwise complicated interparticle interactions taking place at less than one
femtometer scale. One of the greatest and most famous theories- The General Theory of
Relativity which reduces gravity from being a force to being a feeling is at heart a huge
simplification. Last but not least, any hard-core theorist working on fundamental problems in
physics would agree that ‘The principle of Least action’ is the simplest description of our
Universe! But truly is it that simple? Are physicists romanticizing the idea of two rather ugly
equations precisely demonstrating how a cylinder rolls down an incline? Einstein himself
remarked, “Make everything as simple as possible, but not simpler”. It all begins quite intimately
with one proton and one neutron approaching each other to ‘interact’ then all of a sudden they
produce a bunch of offspring using up all the Greek alphabets! However, if we want to elaborate
on ‘interact’, it certainly is not simple anymore. At Least not at face value (looks). Only when we
start to delve deeper do we realize that the way a particle (person) behaves is deeply connected
to some fundamental (internal) properties (traits) such as charge (say e.g. confidence), mass
(introverted), and spin (openness). At this point, some would stop digging deeper but a quantum
field theorist (or a psychotherapist) would love to know the origin of these characteristics. Thus
they find out about sub-particles like quarks and Higgs-bosons which are more fundamental
(like someone’s past experiences or upbringing) using which an entire macroscopic description
of neutron-proton collision (behavior) is possible! The journey from top to bottom and then back
to the top is a one-way journey and is factually the same for everyone. For example, it is a fact
that light always takes the shortest path between two points. This is a very deep concept, still, it
can be interpolated to a more common and straightforward fact- Light travels in a straight line (in
plane geometry). This fact is a result of Fermat's principle postulated in the mid-17th century
and remains valid in all geometries. This is what makes it appealing. The flexibility to
disintegrate it from complicated mathematics to simple terms is what makes a theory beautiful.
“Nature conceals her secrets because she is sublime, not because she is a trickster”-Einstein.
Hence, the truth lies in simplicity, flexibility, and transparency. Conversely, a theory with
exceptions (detours along that journey) ends up being ‘truly’ complicated and too incredible to
believe.
Of course, as the old saying goes, “beauty is in the eye of the beholder” (Molly Bawn by
Margaret Wolfe Hungerford, published in 1878), everything boils down to the group of people
(beholders) to judge whether a theory can be labeled as truly beautiful or oversimplified or
unnecessarily complicated. But ‘facts’ or in some cases ‘universally agreed upon notions’ are
common to any arbitrary group of investigators and should be a natural consequence of that
theory (when verified in independent ways). The word ‘simple’ or ‘beautiful’ when used without
caution can become a misnomer. In reality, all ideas or concepts can be complicated. But what
makes some of them truly beautiful is their internal self-consistency! Beautiful theories are built
from first principles, they are mathematically sound and they can properly explain a certain
physical phenomenon across all scales! Such lofty expectations which come with truly ‘beautiful’
theories often end up describing fundamental physics because she (nature) is sublime. And
such beauty and simplicity are evident at any stage the enthusiast decides to stop along the
round-trip journey.
Intuition, in my opinion, paves the pathway for developing ideas. Without intuition, it is
hard to begin working on a fundamental problem. Since genuine intuition originates only from a
mind which is whole-heartedly immersed in specific thoughts, we can safely say it can be a
guiding light for research. As rightfully stated by Einstein, “The only real valuable thing is
intuition; The intellect has little to do on the road to discovery. There comes a leap in
consciousness, call it Intuition or what you will, the solution comes to you and you don't know
how or why”. While the science of molecular bonds was comparatively well known in the early
19th century, it was the dream of a ‘snake’ catching its tail that allowed Kekule to carry forward
the known facts of chemistry to discover the structure of benzene! Newton’s mind was entirely
into Galileo's works on dynamics when he happened to notice the fruit fall. This stimulated his
mind to attach the idea of an invisible force pulling everything towards itself. Of course, it was
followed by mathematical rigor which justified everything. Taking things a little further, Einstein
famously said that the greatest feeling of his life was witnessing a man falling from his roof! His
intuition took him from being an external observer of falling objects to actually being the falling
object. This very idea is now the fundamental building block of the General Theory of Relativity,
that is, gravity switches off for a body under constant acceleration! Hence, I strongly believe in
the notion that all the greatest ideas or theories are a result of small eureka moments. At every
stage of formulating an idea or theory, those eureka moments get validated by already-known
facts. ‘Intuition’ is what stitches two sets of (sometimes unrelated) facts. But oftentimes, our
‘sixth sense’ could be fooling us and everyone else. Borrowing from Wikipedia the Monty Hall
problem states, “Suppose you're on a game show, and you're given the choice of three doors:
Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host,
who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then
says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice?”.
Even Though our gut might be telling us, “Stick with your choice”, mathematics has shown that
it's always worth switching which has the higher probability to win! The problem is
counter-intuitive when we extend from three doors to say one-hundred doors. When the host
reveals 98 doors that have a goat behind them, our gut will be telling us to switch from our initial
choice. Hence to examine whether our ‘sixth sense’ is not fooling us or others, it must be
followed by a proper examination. Without proper testing, intuition must not be promoted as true
science.
I am currently working on accretion around supermassive black holes called Active Galactic
Nuclei (AGNs). I study them in the X-ray energy range. There is a lot of room for intuitive ideas
in this field especially because it is very model dependent as of now. The X-ray observational
community still doesn't have access to good-quality data because it is difficult to observe X-rays
from an engineering point of view. Hence, we look forward to innovative ideas which can better
explain not just in X-rays but also in the full electromagnetic spectrum, since AGNs shine across
all wavebands. We know very little about the space near black holes. Existing theories provide
the foundation for building intuition which can then be mathematically modeled and fitted to
data. Light rays get bent near the blackhole and focussed on the accretion disk which then gets
reflected. This was an initial guess back in the 70s. Reflection changes the polarization state of
a wave (whose theory was already known for a century) and this simple fact has been
confirmed today with the help of state-of-the-art telescopes. This is one of the very many ideas
which is taking the field forward despite its shortcomings. However, it is worth mentioning that
our results are true only if we believe the data being received by highly sophisticated machinery
located thousands of kilometers from us and operated by space agencies is correct! If not, we
must like science fiction! But fundamentally speaking, the world operates on our faith. Without a
certain amount of faith, existence is meaningless. I have faith in the structural engineer who
designed my building. I take it for granted that NASA is not hiding from us the fact that an
asteroid is going to decimate our city by the next dawn. A certain amount of (blind) faith is what
keeps me going in this field of research.
To sum up, despite its limitations, intuition appears to be a crucial part of human thinking,
according to research. The ability to link seemingly unrelated events is said to aid us in
understanding the chaos of the outside world, while others contend that it is essential to our
ability to perceive events immediately.
