Tag: LIGO India

“Why has no Indian won a science Nobel this year?”

For all their flaws, the science Nobel Prizes – at the time they’re announced, in the first week of October every year – provide a good opportunity to learn about some obscure part of the scientific endeavour with far-reaching consequences for humankind. This year, for example, we learnt about attosecond physics, quantum dots, and in–vitro transcribed mRNA. The respective laureates had roots in Austria, France, Hungary, Russia, Tunisia, and the U.S. Among the many readers that consume articles about these individuals’ work with any zest, the science Nobel Prizes’ announcement is also occasion for a recurring question: how come no scientist from India – such a large country, of so many people with diverse skills, and such heavy investments in research – has won a prize? I thought I’d jot down my version of the answer in this post. There are four factors:

1. Missing the forest for the trees – To believe that there’s a legitimate question in “why has no Indian won a science Nobel Prize of late?” is to suggest that we don’t consider what we read in the news everyday to be connected to our scientific enterprise. Pseudoscience and misinformation are almost everywhere you look. We’re underfunding education, most schools are short-staffed, and teachers are underpaid. R&D allocations by the national government have stagnated. Academic freedom is often stifled in the name of “national interest”. Students and teachers from the so-called ‘non-upper-castes’ are harassed even in higher education centres. Procedural inefficiencies and red tape constantly delay funding to young scholars. Pettiness and politicking rule many universities’ roosts. There are ill-conceived limits on the use, import, and export of biological specimens (and uncertainty about the state’s attitude to it). Political leaders frequently mock scientific literacy. In this milieu, it’s as much about having the resources to do good science as being able to prioritise science.

2. Historical backlog – This year’s science Nobel Prizes have been awarded for work that was conducted in the 1980s and 1990s. This is partly because the winning work has to have demonstrated that it’s of widespread benefit, which takes time (the medicine prize was a notable exception this year because the pandemic accelerated the work’s adoption), and partly because each prize most often – but not always – recognises one particular topic. Given that there are several thousand instances of excellent scientific work, it’s possible, on paper, for the Nobel Prizes to spend several decades awarding scientific work conducted in the 20th century alone. Recall that this was a boom time for science, with the advent of quantum mechanics and the theories of relativity, considerable war-time investment and government support, followed by revolutions in electronics, materials science, spaceflight, genetics, and pharmaceuticals, and then came the internet. It was also the time when India was finding its feet, especially until economic liberalisation in the early 1990s.

3. Lack of visibility of research – Visibility is a unifying theme of the Nobel laureates and their work. That is, you need to do good work as well as be seen to be doing that work. If you come up with a great idea but publish it in an obscure journal with no international readership, you will lose out to someone who came up with the same idea but later, and published it in one of the most-read journals in the world. Scientists don’t willingly opt for obscure journals, of course: publishing in better-read journals isn’t easy because you’re competing with other papers for space, the journals’ editors often have a preference for more sensational work (or sensationalisable work, such as a paper co-authored by an older Nobel laureate; see here), and publishing fees can be prohibitively high. The story of Meghnad Saha, who was nominated for a Nobel Prize but didn’t win, offers an archetypal example. How journals have affected the composition of the scientific literature is a vast and therefore separate topic, but in short, they’ve played a big part to skew it in favour of some kinds of results over others – even if they’re all equally valuable as scientific contributions – and to favour authors from some parts of the world over others. Journals’ biases sit on top of those of universities and research groups.

4. Award fixation – The Nobel Prizes aren’t interested in interrogating the histories and social circumstances in which science (that it considers to be prize-worthy) happens; they simply fete what is. It’s we who must grapple with the consequences of our histories of science, particularly science’s relationship with colonialism, and make reparations. Fixating on winning a science Nobel Prize could also lock our research enterprise – and the public perception of that enterprise – into a paradigm that prefers individual winners. The large international collaboration is a good example: When physicists working with the LHC found the Higgs boson in 2012, two physicists who predicted the particle’s existence in 1964 won the corresponding Nobel Prize. Similarly, when scientists at the LIGO detectors in the US first observed gravitational waves in 2016, three physicists who conceived of LIGO in the 1970s won the prize. Yet the LHC and the LIGOs, and other similar instruments continue to make important contributions to science – directly, by probing reality, and indirectly by supporting research that can be adapted for other fields. One 2007 paper also found that Nobel Prizes have been awarded to inventions only 23% of the time. Does that mean we should just focus on discoveries? That’s a silly way of doing science.

The Nobel Prizes began as the testament of a wealthy Swedish man who was worried about his legacy. He started a foundation that put together a committee to select winners of some prizes every year, with some cash from the man’s considerable fortunes. Over the years, the committee made a habit of looking for and selecting some of the greatest accomplishments of science (but not all), so much so that the laureates’ standing in the scientific community created an aspiration to win the prize. Many prizes begin like the Nobel Prizes did but become irrelevant because they don’t pay enough attention to the relationship between the laureate-selecting process and the prize’s public reputation (note that the Nobel Prizes acquired their reputation in a different era). The Infosys Prize has elevated itself in this way whereas the Indian Science Congress’s prize has undermined itself. India or any Indian for that matter can institute an award that chooses its winners more carefully, and gives them lots of money (which I’m opposed to vis-à-vis senior scientists) to draw popular attention.

There are many reasons an Indian hasn’t won a science Nobel Prize in a while but it’s not the only prize worth winning. Let’s aspire to other, even better, ones.

Feeling the pulse of the space-time continuum

The Copernican
April 17, 2014

Haaaaaave you met PSR B1913+16? The first three letters of its name indicate it’s a pulsating radio source, an object in the universe that gives off energy as radio waves at very specific periods. More commonly, such sources are known as pulsars, a portmanteau of pulsating stars.

When heavy stars run out of hydrogen to fuse into helium, they undergo a series of processes that sees them stripped off their once-splendid upper layers, leaving behind a core of matter called a neutron star. It is extremely dense, extremely hot, and spinning very fast. When it emits electromagnetic radiation in flashes, it is called a pulsar. PSR B1913+16 is one such pulsar, discovered in 1974, located in the constellation Aquila some 21,000 light-years from Earth.

Finding PSR B1913+16 earned its discoverers the Nobel Prize for physics in 1993 because this was no ordinary pulsar, and it was the first to be discovered of its kind: of binary stars. As the ‘B’ in its name indicates, it is locked in an epic pirouette with a nearby neutron star, the two spinning around each other with the orbit’s total diameter spanning one to five times that of our Sun.

Losing energy but how?

The discoverers were Americans Russell Alan Hulse and Joseph Hooton Taylor, Jr., of the University of Massachusetts Amherst, and their prize-winning discovery didn’t culminate with just spotting the binary pulsar that has come to be named after them. Further, they found that the pulsar’s orbit was shrinking, meaning the system as a whole was losing energy. They found that they could also predict the rate at which the orbit was shrinking using the general theory of relativity.

In other words, PSR B1913+16 was losing energy as gravitational energy while proving a direct (natural) experiment to verify Albert Einstein’s monumental theory from a century ago. (That a human was able to intuit how two neutron stars orbiting each other trillions of miles away could lose energy is homage to the uniformity of the laws of physics. Through the vast darkness of space, we can strip away with our minds any strangeness of its farthest reaches because what is available on a speck of blue is what is available there, too.)

While gravitational energy, and gravitational waves with it, might seem like an esoteric concept, it is easily intuited as the gravitational analogue of electromagnetic energy (and electromagnetic waves). Electromagnetism and gravitation are the two most accessible of the four fundamental forces of nature. When a system of charged particles moves, it lets off electromagnetic energy and so becomes less energetic over time. Similarly, when a system of massive objects moves, it lets off gravitational energy… right?

“Yeah. Think of mass as charge,” says Tarun Souradeep, a professor at the Inter-University Centre for Astronomy and Astrophysics, Pune, India. “Electromagnetic waves come with two charges that can make up a dipole. But the conservation of momentum prevents gravitational radiation from having dipoles.”

According to Albert Einstein and his general theory of relativity, gravitation is a force born due to the curvature, or roundedness, of the space-time continuum: space-time bends around massive objects (an effect very noticeable during gravitational lensing). When massive objects accelerate through the continuum, they set off waves in it that travel at the speed of light. These are called gravitational waves.

“The efficiency of energy conversion – from the bodies into gravitational waves – is very high,” Prof. Souradeep clarifies. “But they’re difficult to detect because they don’t interact with matter.”

Albie’s still got it

In 2004, Joseph Taylor, Jr., and Joel Weisberg published a paper analysing 30 years of observations of PSR B1913+16, and found that general relativity was able to explain the rate of orbit contraction within an error of 0.2 per cent. Should you argue that the binary system could be losing its energy in many different ways, that the theory of general relativity is able to so accurately explain it means that the theory is involved, and in the form of gravitational waves.

Prof. Souradeep says, “According to Newtonian gravity, the gravitational pull of the Sun on Earth was instantaneous action at a distance. But now we know light takes eight minutes to come from the Sun to Earth, which means the star’s gravitational pull must also take eight minutes to affect Earth. This is why we have causality, with gravitational waves in a radiative mode.”

And this is proof that the waves exist, at least definitely in theory. They provide a simple, coherent explanation for a well-defined problem – like a hole in a giant jigsaw puzzle that we know only a certain kind of piece can fill. The fundamental particles called neutrinos were discovered through a similar process.

These particles, like gravitational waves, hardly interact with matter and are tenaciously elusive. Their discovery was predicted by the physicist Wolfgang Pauli in 1930. He needed such a particle to explain how the heavier neutron could decay into the lighter proton, the remaining mass (or energy) being carried away by an electron and a neutrino antiparticle. And the team that first observed neutrinos in an experiment, in 1942, did find it under these circumstances.

Waiting for a direct detection

On March 17, radio-astronomers from the Harvard-Smithsonian Centre for Astrophysics (CfA) announced a more recent finding that points to the existence of gravitational waves, albeit in a more powerful and ancient avatar. Using a telescope called BICEP2 located at the South Pole, they found the waves’ unique signature imprinted on the cosmic microwave background, a dim field of energy leftover from the Big Bang and visible to this day.

At the time, Chao-Lin Kuo, a co-leader of the BICEP2 collaboration, had said, “We have made the first direct image of gravitational waves, or ripples in space-time across the primordial sky, and verified a theory about the creation of the whole universe.”

Spotting the waves themselves, directly, in our human form is impossible. This is why the CfA discovery and the orbital characteristics of PSR B1913+16 are as direct detections as they get. In fact, finding one concise theory to explain actions and events in varied settings is a good way to surmise that such a theory could exist.

For instance, there is another experiment whose sole purpose has been to find gravitational waves, using laser. Its name is LIGO (Laser Interferometer Gravitational-wave Observatory). Its first phase operated from 2002 to 2010, and found no conclusive evidence of gravitational waves to report. Its second phase is due to start this year, in 2014, in an advanced form. On April 16, the LIGO collaboration put out a 20-minute documentary titled Passion for Understanding, about the “raw enthusiasm and excitement of those scientists and researchers who have dedicated their professional careers to this immense undertaking”.

The laser pendula

LIGO works like a pendulum to try and detect gravitational waves. With a pendulum, there is a suspended bob that goes back and forth between two points with a constant rhythm. Now, imagine there are two pendulums swinging parallel to each other but slightly out of phase, between two parallel lines 1 and 2. So when pendulum A reaches line 1, pendulum B hasn’t got there just yet, but it will soon enough.

When gravitational waves, comprising peaks and valleys of gravitational energy, surf through the space-time continuum, they induce corresponding crests and troughs that distort the metrics of space and passage of time in that area. When the two super-dense neutron stars that comprise PSR B1913+16 move around each other, they must be letting off gravitational waves in a similar manner, too.

When such a wave passes through the area where we are performing our pendulums experiment, they are likely to distort their arrival times to lines 1 and 2. Such a delay can be observed and recorded by sensitive instruments.

Analogously, LIGO uses beams of light generated by a laser at one point to bounce back and forth between mirrors for some time, and reconvene at a point. And instead of relying on the relatively clumsy mechanisms of swinging pendulums, scientists leverage the wave properties of light to make the measurement of a delay more precise.

At the beach, you’ll remember having seen waves forming in the distance, building up in height as they reach shallower depths, and then crashing in a spray of water on the shore. You might also have seen waves becoming bigger by combining. That is, when the crests of waves combine, they form a much bigger crest; when a crest and a trough combine, the effect is to cancel each other. (Of course this is an exaggeration. Matters are far less exact and pronounced on the beach.)

Similarly, the waves of laser light in LIGO are tuned such that, in the absence of a gravitational wave, what reaches the detector – an interferometer – is one crest and one trough, cancelling each other out and leaving no signal. In the presence of a gravitational wave, there is likely to be one crest and another crest, too, leaving behind a signal.

A blind spot

In an eight-year hunt for this signal, LIGO hasn’t found it. However, this isn’t the end because, like all waves, gravitational waves should also have a frequency, and it can be anywhere in a ginormous band if theoretical physicists are to be believed (and they are to be): between 10-7 and 1011 hertz. LIGO will help humankind figure out which frequency ranges can be ruled out.

In 2014, the observatory will also reawaken after four-years of being dormant and receiving upgrades to improve its sensitivity and accuracy. According to Prof. Souradeep, the latter now stands at 10-20 m. One more way in which LIGO is being equipped to find gravitational waves is by created a network of LIGO detectors around Earth. There are already two in the US, one in Europe, and one in Japan (although the Japanese LIGO uses a different technique).

But though the network improves our ability to detect gravitational waves, it presents another problem. “These detectors are on a single plane, making them blind to a few hundred degrees of the sky,” Prof. Souradeep says. This means the detectors will experience the effects of a gravitational wave but if it originated from a blind spot, they won’t be able to get a fix on its source: “It will be like trying to find MH370!” Fortunately, since 2010, there have been many ways proposed to solve this problem, and work on some of them is under way.

One of them is called eLISA, for Evolved Laser Interferometer Space Antenna. It will attempt to detect and measure gravitational waves by monitoring the locations of three spacecraft arranged in an equilateral triangle moving in a Sun-centric orbit. eLISA is expected to be launched only two decades from now, although a proof-of-concept mission has been planned by the European Space Agency for 2015.

Another solution is to install a LIGO detector on ground and outside the plane of the other three – such as in India. According to Prof. Souradeep, LIGO-India will reduce the size of the blind spot to a few tens of degrees – an order of magnitude improvement. The country’s Planning Commission has given its go-ahead for the project as a ‘mega-science project’ in the 12th Five Year Plan, and the Department of Atomic Energy, which is spearheading the project, has submitted a note to the Union Cabinet for approval. With the general elections going on in the country, physicists will have to wait until at least June or July to expect to get this final clearance.

Once cleared, of course, it will prove a big step forward not just for the Indian scientific community but also for the global one, marking the next big step – and possibly a more definitive one – in a journey that started with a strange pulsar 21,000 light-years away. As we get better at studying these waves, we have access to a universe visible not just in visible light, radio-waves, X-rays or neutrinos but also through its gravitational susurration – like feeling the pulse of the space-time continuum itself.