Roundup of missed stories – May 23, 2015

I’ve missed writing/commenting on so many science papers/articles in the two weeks following the launch of The Wire. The concepts in many of them would’ve made fun explainers, some required a takedown or two, and one had surprising ethical and philosophical implications. I think it might be a bit late to write about them myself (read: too tired), so I’m going to lay those I think are the best among them out here for you to take on in ways you see fit.

  1. Disrupting the subscription journals’ business model for the necessary large-scale transformation to open access – An OA whitepaper from a big proponent of OA, the Max Planck Digital Library. Has data to support argument that money locked in the currently dominant publishing paradigm needs to be repurposed for OA, which the whitepaper reasons is very viable. Finally, suggests that for OA to become the dominant paradigm, it must happen en masse instead of in piecemeal fashion.
  2. Self-assembling Sierpinski triangles – Sierpinski triangles are a prominent kind of fractal. So, “Defect-free Sierpiński triangles can be self-assembled on a silver surface through a combination of molecular design and thermal annealing” suggests some interesting chemical and physical reactions at play.
  3. The moral challenge of invisibility – A new optical technique allows people to look at their bodies and see nothing, thanks to an apparatus developed by a team of researchers from the Karolinska Institute in Sweden. Cool as it is, physicist Philip Ball writes that users of the technique felt their social anxieties reduce. This appears to be a curious axiom of VS Ramachandran’s mirror-box technique to reduce phantom-limb pain in amputees.
  4. Open Science decoded – “Granting access to publications and data may be a step towards open science, but it’s not enough to ensure reproducibility. Making computer code available is also necessary — but the emphasis must be on the quality of the programming.” Given the role computing and statistics are playing in validating or invalidating scientific results, I wholeheartedly agree.
  5. EPR Paradox: Nonlocal legacy – I haven’t read this article yet but it already sounds interesting.
  6. In the beginning – A long piece in Aeon discusses if cosmology is suffering a drought of creativity these days. The piece’s peg is on the BICEP2 fiasco so maybe there are some juicy inside-stories there. It also ends on a well-crafted note of hopelessness (that’s one thing I’ve noticed about longform – the graf is often the last para).

We might be trapped in this snow globe of photons forever. The expansion of the Universe is pulling light away from us at a furious pace. And even if it weren’t, not everything that exists can be observed. There are more things in Heaven and Earth than are dreamt of in our philosophies. There always will be. Science has limits. One day, we might feel ourselves pressing up against those limits, and at that point, it might be necessary to retreat into the realm of ideas. It might be necessary to ‘dispense with the starry heavens’, as Plato suggested. It might be necessary to settle for untestable theories. But not yet. Not when we have just begun to build telescopes. Not when we have just awakened into this cosmos, as from a dream.

Last: I foresee I’ll continue to miss writing on these pieces in the future, so maybe these roundups could become a regular feature.

As the ripples in space-time blow through dust…

The last time a big announcement in science was followed by an at least partly successful furor to invalidate it was when physicists at the Gran Sasso National Laboratory, Italy, claimed to have recorded a few neutrinos travelling at faster than the speed of light. In this case, most if not all scientists know something had to be wrong. That nothing can clock such speeds except electromagnetic radiation is set in stone for all practical purposes.


Although astronomers from Harvard University’s Center for Astrophysics (CfA) made a more plausible claim on March 17 on having found evidence of primordial gravitational waves, they do have something in common with the superluminal-neutrinos announcement: prematurity. Since the announcement, it has emerged that the CfA team didn’t account for some observations that would’ve seriously disputed their claims even though, presumably, they were aware that such observations existed. Something like willful negligence…

Imagine receiving a tight slap to the right side of face. If there was good enough contact, the slapper’s fingers should be visible for some time on your right cheek before fading away. Your left cheek should bear mostly no signs of you having just been slapped. The CfA astronomers were trying to look for a similar fingerprint in a sea of energy found throughout the universe. If they found the fingerprint, they’d know the energy was polarized, or ‘slapped’, by primordial gravitational waves more than 13 billion years ago. To be specific, the gravitational waves – which are ripples in space-time – would only have polarized one of two components the energy contains: the B-mode (‘right cheek’), the other being the E-mode (‘left cheek’).

The Dark Sector Lab (DSL), located 3/4 of a mile from the Geographic South Pole, houses the BICEP2 telescope (left) and the South Pole Telescope (right).
The Dark Sector Lab (DSL), located 3/4 of a mile from the Geographic South Pole, houses the BICEP2 telescope (left) and the South Pole Telescope (right). Image:

On March 17, CfA astronomers made the announcement that they’d found evidence of B-mode polarization using a telescope situated at the South Pole called BICEP2, hallelujah! Everyone was excited. Many journalists wrote articles without exercising sufficient caution, including me. Then, just the next day I found an astronomy blog that basically said, “Hold on right there…” The author’s contention was that CfA had looked only at certain parts of the sea of energy to come to their conclusion. The rest of the ‘cheek’ was still unexplored, and the blogger believed that if they checked out those areas, the fingerprints actually might not be there (for the life of me I can’t find the blog right now).

“Right from the time of BICEP2 announcement, some important lacunae have been nagging the serious-minded,” N.D. Hari Dass, an adjunct professor at Chennai Mathematical Institute told me. From the instrumental side, he said, there was the possibility of cross-talk between measurements of polarization and of temperature, and between measurements on the E-mode and on the B-mode. On the observational front, CfA simply hadn’t studied all parts of the sky – just one patch above the South Pole where B-mode polarization seemed significant. And they had studied that one patch by filtering for one specific temperature, not a range of temperatures.

“The effect should be frequency-independent if it were truly galactic,” Prof. Dass said.

The Milky Way galaxy’s magnetic fingerprint according to observations by the Planck space telescope. Image: ESA

But the biggest challenge came from quarters that questioned how CfA could confirm the ‘slappers’ were indeed primordial gravitational waves and not something else. Subir Sarkar, a physicist at Oxford University, and his colleagues were able to show that what BICEP2 saw to be B-mode polarization could actually have been from diffuse radio emissions from the Milky Way and magnetized dust. The pot was stirred further when the Planck space telescope team released a newly composed map of magnetic fields across the sky but blanked out the region where BICEP2 had made its observations.

There was reasonable, and it persists… More Planck data is expected by the end of the year and that might lay some contentions to rest.

On June 3, physicist Paul Steinhardt made a provocative claim in Nature: “The inflationary paradigm” – which accounts for B-mode polarization due to gravitational waves – “is fundamentally untestable, and hence scientifically meaningless”. Steinhardt was saying that the theory supposed to back the CfA quest was more like a tautology and that it would be true no matter the outcome. I asked Prof. Dass about this and he agreed.

A tautology at work.
A tautology at work.

“Inflation is a very big saga with various dimensions and consequences. One of Steinhardt’s
points is that the multiverse aspect” – which it allows for – “can never be falsified as every conceivable value predict will manifest,” he explained. “In other words, there are no predictions.” Turns out the Nature claim wasn’t provocative at all, implying CfA did not set itself well-defined goals to overcome these ‘axiomatic’ pitfalls or that it did but fell prey to sampling bias. At this point, Prof. Dass said, “current debates have reached some startling professional lows with each side blowing their own trumpets.

It wasn’t as if BICEP2 was the only telescope making these observations. Even in the week leading up to March 17, in fact, another South Pole telescope named Polarbear announced that it had found some evidence for B-mode polarization in the sky (see tweet below). The right thing to do now, then, would be to do what we’re starting to find very hard: be patient and be critical.

The magnetic sky

On May 6, the team behind the now-inoperative Planck space telescope released a map of the magnetic field pervading the Milky Way galaxy.


Titled ‘Milky Way’s Magnetic Fingerprint’, the map incorporates two textures to visualize the magnetic field’s dual qualities: striations for direction and shading for intensity.

Planck was able to measure the polarization by studying light. Light is a wave (apart from being a particle, too). As a wave, it is composed of electric and magnetic fields vibrating perpendicular to each other. Overall, however, the two fields could vibrate in any direction. So when they choose to vibrate in a particular direction, the light is said to be polarized.

Such light is emitted by dust grains strewn in the space between Milky Way’s stars. As Dr. Chris Tibbs, an astrophysicist from Caltech, told me over Twitter, “Dust grains absorb light from stars, which heats up the grains, and [they] then radiate away this heat producing the emission.”

The grains are oriented along the Milky Way’s magnetic field, so the light they emit is polarized along the magnetic field. Because the grains are so small, the light they emit is of very low intensity (i.e. very long wavelength), so it takes a powerful telescope like Planck, perched on its orbit around the Sun, to study it.

It used a technique that’s the opposite of polarized sunglasses, which use filters to eliminate polarized light and reduce glare. The telescope, on the other hand, used filters to eliminate all but the polarized light, and then studied it to construct the map shown above.

As the astrophysicist Katie Mack pointed out on her Facebook page, the Planck team that released this image has carefully left out showing the magnetic fields in the region of the sky studied by the BICEP2 telescope at the South Pole which, on March 17, announced the discovery of evidence pointing to cosmic inflation. According to Katie,

The amount of polarized dust emission in the region where BICEP2 made its observation is unknown, but if it turns out to be a lot, it could mean that the signal BICEP2 saw was not entirely primordial.

This means we’ve to wait until the end of the year to know if the BICEP2 announcements were all they were made out to be.

The Big Bang did bang

The Hindu
March 19, 2014

On March 17, the most important day for cosmology in over a decade, the Harvard-Smithsonian Centre for Astrophysics made an announcement that swept even physicists off their feet. Scientists published the first pieces of evidence that a popular but untested theory called cosmic inflation is right. This has significant implications for the field of cosmology.

The results also highlight a deep connection between the force of gravitation and quantum mechanics. This has been the subject of one of the most enduring quests in physics.

Marc Kamionkowski, professor of physics and astronomy at Johns Hopkins University, said the results were a “smoking gun for inflation,” at a news conference. Avi Loeb, a theoretical physicist from Harvard University, added that “the results also tell us when inflation took place and how powerful the process was.” Neither was involved in the project.

Rapid expansion

Cosmic inflation was first hypothesized by American physicist Alan Guth. He was trying to answer the question why distant parts of the universe were similar even though they couldn’t have shared a common history. In 1980, he proposed a radical solution. He theorized that 10-36 seconds after the Big Bang happened, all matter and radiation was uniformly packed into a volume the size of a proton.

In the next few instants, its volume increased by 1078 times – a period called the inflationary epoch. After this event, the universe was almost as big as a grapefruit, expanding to this day but at a slower pace. While this theory was poised to resolve many cosmological issues, it was difficult to prove. To get this far, scientists from the Centre used the BICEP2 telescope stationed at the South Pole.

BICEP (Background Imaging of Cosmic Extragalactic Polarization) 2 studies some residual energy of the Big Bang called the cosmic microwave background (CMB). This is a field of microwave radiation that permeates the universe. Its temperature is about 3 Kelvin. The CMB consists of electric (E) and magnetic (B) fields, called modes.

Polarized radiation

Before proceeding further, consider this analogy. When sunlight strikes a smooth, non-metallic surface, like a lake, the particles of light start vibrating parallel to the lake’s surface, becoming polarized. This is what we see as glare. Similarly, the E-mode and B-mode of the CMB are also polarized in certain ways.

The E-mode is polarized because of interactions with scattered photons and electrons in the universe. It is the easier to detect than the B-mode, and was studied in great detail until 2012 by the Planck space telescope. The B-mode, on the other hand, can be polarized only under the effect of gravitational waves. These are waves of purely gravitational energy capable of stretching or squeezing the space-time continuum.

The inflationary epoch is thought to have set off gravitational waves rippling through the continuum, in the process polarizing the B-mode.

To find this, a team of scientists led by John Kovac from Harvard University used the BICEP2 telescope from 2010 to 2012. It was equipped with a lens of aperture 26 cm, and devices called bolometers to detect the power of the CMB section being studied.

The telescope’s camera is actually a jumble of electronics. “The circuit board included an antenna to focus and filter polarized light, a micro-machined detector that turns the radiation into heat, and a superconducting thermometer to measure this heat,” explained Jamie Bock, a physics professor at the California Institute of Technology and project co-leader.

It scanned an effective area of two to 10 times the width of the Moon. The signal denoting effects of gravitational waves on the B-mode was confirmed with a statistical significance of over 5σ, sufficient to claim evidence.

Prof. Kovac said in a statement, “Detecting this signal is one of the most important goals in cosmology today.”

Unified theory

Despite many physicists calling the BICEP2 results as the first direct evidence of gravitational waves, theoretical physicist Carlo Rovelli advised caution. “The first direct detection is not here yet,” he tweeted, alluding to the scientists only having found the waves’ signatures.

Scientists are also looking for the value of a parameter called r, which describes the level of impact that gravitational waves could have had on galaxy formation. That value has been found to be particularly high: 0.20 (+0.07 –0.05). This helps explain why galaxies formed so rapidly, how powerful inflation was and why the universe is so large.

Now, astrophysicists from other observatories around the world will try to replicate BICEP2’s results. Also, data from the Planck telescope on the B-mode is due in 2015.

It is notable that gravitational waves are a feature of theories of gravitation, and cosmic inflation is a feature of quantum mechanics. Thus, the BICEP2 results show that the two previously exclusive theories can be combined at a fundamental level. This throws open the door for theoretical physicists and string theorists to explore a unified theory of nature in new light.

Liam McAllister, a physicist from Cornell University, proclaimed, “In terms of impact on fundamental physics, particularly as a tool for testing ideas about quantum gravity, the detection of primordial gravitational waves is completely unprecedented.”