The Berry phase of Kancha Gachibowli
There’s a concept in quantum mechanics, and also in parts of classical mechanics, called the Berry phase. Say you’re walking around a mountain. You start off along a path and follow it all the way until you’re back to the point where you started. You’re at the same point, sure, but you’re probably facing a different direction now. The Berry phase works something like this. Say you’ve got a bunch of electrons that you’re manipulating using a magnetic field. As you vary the field in continuous increments, the electrons will respond continuously in some way. But as you vary the field through a cycle of changes and bring it back to the original setting, the electrons won’t exactly be at their original configuration as well. Or they will be in addition to some change. This ‘additional change’ is called the Berry phase.
Reading about the Kancha Gachibowli forest brought the Berry phase to mind. Yesterday, India’s new Chief Justice, B.R. Gavai, faced Telangana state with a choice: “between restoring the forest or having the Chief Secretary and [half a dozen] officials in prison,” per The Hindu. The latter people are being held responsible for attempting to divert mostly moderately and densely forested land to a planned campus for information technology companies. The court had no sympathy for Telangana counsel Abhishek Manu Singhvi’s argument that the state’s efforts had been good-intentioned. The principle reason: the state hasn’t been able to explain the fact that it organised a phalanx of bulldozers to bring down 104 acres of old trees during an extended weekend, when the courts were closed, leaving the felling’s opponents without access to legal recourse. A few telling passages from The Hindu:
The State had previously denied the land was a forest. The claim, it said, that the area was forest land had sprung up only after developmental activities commenced following the allotment of the land to the Telangana Industrial Infrastructure Corporation. Mr. Singhvi submitted that the processes regarding the allotment had been on since March 2024. He said the intention of the State was bona fide.
…
Mr. Singhvi maintained that “thousands” of trees were not cut. “We have seen the photographs,” Chief Justice Gavai responded.
Mr. Singhvi submitted that not a leaf has been moved on the site after the apex court ordered everything to be stopped on April 16. The State was complying with the court’s direction in letter and spirit. A huge afforestation programme was underway in the area.
Amicus curiae, senior advocate K. Parameshwar, drew the attention of the court to a finding in a Forest Survey of India report, which was forwarded to the Central Empowered Committee, that out of the 104 acres cut in two nights, over 60% had been moderately and heavily dense forest.
It’s worthwhile these days to treat the concept of afforestation as a yellow flag at best and a despicable idea at worst. In the last decade it has evolved regressively into a sort of olive branch offered up alongside casual excuses to divert forested land for non-forest uses, often in open defiance of India’s existing forest protection laws — which sadly have been increasingly enfeebled by the environment ministry. That the state is now afforesting the area is little consolation because the trees that have already been cut represent a greater ecological loss than that can be recouped by young plants anytime in the near future. We may have come full circle since the state first felled the trees but we bear the burden of an additional change as well.
In fact, this could be more like magnetic hysteresis than the Berry phase depending on the mode of afforestation. Quantum systems are said to have acquired a Berry phase when they undergo a reversible process in which entropy doesn’t increase*. But entropy, the amount of disorder, has indeed increased. We’ve lost energy. We’ve lost old trees and their ecosystem services. We’ve lost a sustainable carbon store. We’ve learnt that the Telangana government is willing to act in bad faith. We’ve learnt that our forest protection laws continue to not work. Why, we’ve been reminded that the Supreme Court remains the country’s last democratic institution, perhaps short of Parliamentary majority, prepared to measure the loss of green cover by the precepts of sustainable development. Every Supreme Court decision to stall a project that entails deforestation has been met with cheers in the conservation and environmental justice communities but each such verdict also serves a reminder that we remain at the mercy of the last line of defence. If someday the Supreme Court also yields, or is let down by Parliament passing a law that makes a mockery of protecting trees, we are only left with protest — like the brave students of the University of Hyderabad mounted to bring the Kancha Gachibowli issue to the whole country’s attention.
When you apply a magnetic field over a ferromagnet, like a block of iron, it becomes magnetised. If you remove the magnetic field, the block stays magnetised to some degree. This phenomenon is called remanence. Future attempts to magnetise and demagnetise the block will have to work against the remanence, causing the block to lose energy over time as heat. This macroscopic feature is called magnetic hysteresis**: it’s irreversible, dissipative, disorderly, and vexatious. Much like the state of Telangana, it claims to find value in the context of computers (disk drives in particular), and much like the trees of Kancha Gachibowli, there’s nothing a ferromagnet can do about it.
* I’ve used entropy here with reference to a quantum adiabatic process. In a thermodynamic adiabatic process, entropy isn’t produced only if the process is also reversible.
** The term ‘hysteresis’ comes from the Greek ‘hústeros’, meaning ‘later’. This is a reference to the shape of the curve on a graph with the strength of the magnetic field H on one axis and the magnetisation M on the other. As the H curve rises and falls, the M curve starts to fall behind. The seemingly closely related ‘hysteria’ comes from the Greek ‘hustéra’, for ‘womb’, and is thus unrelated. However, the well-known Cornell University physicist James P. Sethna wrote sometime before 1995:
There seems to be no etymological link between hysteresis and either hysterical (fr. L hystericus of the womb) or history (fr. Gk, inquiry, history, fr. histor, istor knowing, learned). This is too bad, as there are scientific connections to both words. (There is no link, scientific or etymological, to histolysis, the breakdown of bodily tissues, or to blood.) … Many hysteretic systems make screeching noises as they respond to their external load (hence, the natural connection with hysteria).
‘Hysteria’ has of course rightly fallen out of favour both within and without clinical contexts.
