This is a guest post by my friend Pinkesh Patel, a data scientist at Facebook. Pinkesh has a PhD in physics from Caltech during which he worked on LIGO, the gravitational wave detector. He then did research in computational biology at Stanford after which he moved to Facebook. Pinkesh is thus ideally poised to think about the whole spectrum of scientific domains and cultures, from hard physics to “soft” sociology.

The post was sparked by a conversation we had in which I lamented the gaping chasm I felt existed between the discovery of inflation and our inability to design even simple drugs against diseases like cancer or Alzheimer's. Pinkesh reminded me that this is because even a supposedly overarching science like physics actually has a very limited set of domains of applicability and that science is really all about “domain expertise”; as Pinkesh puts it, we have to distinguish the scale of a science from its reach. Most importantly, he underscores the sense of wonder that all of us should feel about any scientific discovery, no matter what field it is in. Great discoveries are not about specific fields; they are about a convergence of everything that humanity has achieved since its beginnings, and of this we should all be proud. I agree.

“How are you feeling, mom?” asked Eric, a thirty something chemist who wasn’t sure how exactly he would answer that question himself after having spent a large portion of his day modeling the ATP binding pocket of an obscure protein. He was visiting his sixty five year old mother who was convalescing after a particularly brutal course of chemotherapy that the doctors had hoped would deliver the coup de grace to her breast cancer.

“I haven’t felt better in ages!” said Helga, clearly grimacing as she turned to face her son. Given his puzzled look, she corrected herself “Oh, the chemo is terrible, especially the constant nausea, however its quite something to think that we can answer questions about the possibility that we live in a multiverse and that gravity is a quantum phenomenon after all.” “Been surfing the old Internet have we?” quipped Eric. “Oh the news just keeps rolling in and this whole Internet thing has been quite a hoot for somewhat amateur followers of science like myself. Take this Sean Carroll fellow and his wonderful writing for instance…” said Helga, her enthusiasm only interrupted by a thirty second bout of coughing.

“I am glad that this news has piqued your curiosity and taken your mind off of this awful ‘treatment’ regimen,” said Eric, while straightening his ailing mother’s hair. He continued “But why does this stuff interest you so? You are an experimental condensed matter physicist and have always been interested in esoteric things like two-dimensional electron gases and their ilk.” “You see my son, when you get to my age, or perhaps once you are wise enough to realize that you are not special, you start looking for grandeur elsewhere and what is more special than …” said Helga, interrupted by another bout of coughing.

“See, this is what I don’t get. How can we, the ape that looked forward, the only intelligent thing in the known universe, understand concepts such as what happened a few trillionth of a second after the big bang and yet not cure this awful illness?” asked Eric. “How come I cannot even make my simulation code not run for more than a few nano-seconds, with only a few hundred atoms to deal with, whilst we can simulate the impact of quantum fluctuations of space and time and detect their impact on light 400,000 years later, that too after 13.8 billion years of travel?” A smile appeared over Helga’s face. She had obviously pondered along similar lines countless times, mostly driven by the ostensibly innocent questions of her students.

“Eric, it's because you are giving too little credit to the other sciences and because you are confusing the scale of an idea with its reach. When the Bohr model of the atom could explain the Balmer emission spectra, he had not explained everything that was to be known about electrons and protons. Far from it, he had barely scratched the surface. Dig a little deeper and you see the Zeeman effect of the fine splitting of these spectral lines and oh boy, you have a decade more of work and new concepts such as the exclusion principle that need to be invented. And that was just the hydrogen atom. You think that just because the scale of physics is large, that its reach is also large. I am a physicist and I know some of the limitations of my field. It works wonderfully in small boxes of the universe or if we consider the universe itself as a big box, where we abstract away all the things that we, the ape that looked forward, hold dear” said Helga.

“That’s all well and good and I applaud the work done by physicists, but in my own little corner of science it feels like we are savages who cannot even understand the basic tenets of our endeavor,” lamented Eric. “That is because you think that the ideas that are needed to make progress in your field are a subset of the ideas about the entire universe, but nothing could be farther from the truth. Yes your piece of the universe is a subset of the universe as a whole, however in that case we have abstracted things like galaxies and human beings away as what we call ‘higher order terms’. Zoomed out, pesky things like human beings don’t impact the universe, and it is not the scale of your pursuit that determines its difficulty. So in essence physics is the first order approximation of the universe, but we all live in the world of second, third, … fifty-fifth order approximations and the first order sheds no light on these ‘higher orders’“ replied Helga.

“Yes, yes I have heard all that. Physics is the easiest of the sciences as it is the most controlled, limited in scope etc. But these seem to be bedtime stories that we biologists tell ourselves to sleep soundly” said Eric. “We cannot even understand what is making your cells grow wildly and kill you in the very same organ that nourished me in my first moments, whilst we know what nourished the universe in its first moments. How do I reconcile with these facts?” continued Eric. “It is again because you think that physics discovered this and that you biologists didn’t have anything to do with it” replied Helga.

Noticing his puzzled look, she carried on “See, think about the chain of events that make us think that the inflationary theory is true: We have a representation of space and time in our heads and a representation of the known facts about the universe such as its flatness, homogeneity etc. We make a leap of faith from this representation and reconcile it with other known facts about the universe to predict that if such and such is true, then these fluctuations ought to leave a signature in the cosmic microwave background photons. We then use our knowledge of the Earth and decide to put up our observatory to detect these photons, which happen to be in the microwave band and are readily absorbed by moisture, in the driest place on the planet. Leave alone the fact that we have not evolved to live or work there, but we manage to do it regardless and transport this machine there. We use the latest in condensed matter physics and our understanding of quantum mechanics to make the most sensitive possible instruments. We store the data we collect using other fields of knowledge such as the giant magneto resistance and then we use error correcting codes to transmit this data without errors from objects we set up orbiting the planet to our homes. This data is then processed using other wonderful instruments known as computers, which I admit to not understanding fully. We then display it using liquid crystal display technology using a medium of scientific representation such as graphs. Then comes the crazy part, we jump across these umpteen series of representations to the bare fact that the universe underwent inflation. Try explaining how this is “Physics” and not hundreds of other human endeavors to an alien.”

“And why stop there, what made it possible for us to have the free time to ponder such questions in the first place? Inventions such as agriculture, law and order, money to name just a few. The tapestry of science is woven using all the threads of all fields of human endeavor. You cannot just disentangle one and say that that one is advanced and the others are lagging behind. The victories and defeats of all of these fields belong to all of us.

Yes, I wish we could cure this accursed disease and many others like it, but we will get there my son. The same evolutionary process that accidentally made me joyful due to some abstract coarse grained simulation of the universe in my head, also makes me not care for my own well being, but of humanity’s as a whole. I will die, but we will solve these and other problems together, not as physicists, chemists, barbers and politicians, but as human beings” said Helga, as another bout of coughing made it impossible to continue the conversation any further that evening.