Casual setting, critical thinking

BookLab podcast explores ideas from modern physics to genetic testing

Casual setting, critical thinking

By listening to BookLab, a podcast by science journalists Amanda Gefter and Dan Falk, I better understood what makes science writing engaging and how to think critically about what I read, even if the authors are experts in their field.

BookLab describes itself as a series “that puts science books under the microscope.” Though Gefter and Falk specialize in physics reporting, they don’t shy away from exploring topics from a diverse range of fields.

Their discussions include books on how medicine may drastically change due to technology, unexpected implications of modern physics, issues with genetic testing, and much more.

Gefter and Falk integrate their experiences as science journalists into their discussions, exploring how certain sections of a book relate to recent discoveries they’ve reported on, and how their personal experiences can serve as examples of a key concept.

They bring in their experiences as longform writers, exploring how writers successfully distil complex ideas into accessible forms, and how poetic language can be distinctively used to capture an idea into words.

Each episode starts off by introducing the broad theme explored by a book under review. Gefter and Falk then provide a brief overlay of the writing, discuss particular parts of the book that stood out to them, and observations about the writings and arguments of the authors.

The episodes conclude with a brief segment called “What’s on your nightstand?”, in which each journalist describes a science book they’ve been reading recently, and what they liked about it.

It’s rare to find a podcast hosted by science journalists in a casual setting, as opposed to researchers or journalists in a professional setting. BookLab fits that niche and is engaging for scientists and science enthusiasts alike.

A duel of theories: quantum mechanics, general relativity — or both?

Talks by researchers during Science Rendezvous festival illuminate theories of physics

A duel of theories: quantum mechanics, general relativity — or both?

From the Department of Physics, Professor A. W. Peet and post-doctoral fellow Aharon Brodutch delivered two related yet different talks about crucial theories of physics to a wide range of attendees of the May 11 Science Rendezvous street festival on the St. George campus.

Gravity causes black holes to exist

Even if you dozed off in high school physics lectures, there’s almost no way you haven’t heard of black holes. Just over a month ago, NASA published the first ever image of a black hole, which left the world in utter awe.

But what causes black holes to exist? To answer, Peet began by explaining the theory of gravity.

We are all familiar with the force of gravity: you drop a tennis ball, and it falls downwards. Gravity is the invisible force that is responsible for the attraction of all objects to each other. Furthermore, the strength of the force is directly related to the object’s mass. The larger the mass, the larger the force of attraction between the objects.

However, gravity not only attracts mass, but it also pulls on light — despite the fact that light is composed of massless particles.

How can gravity ever be strong enough to trap massless light?

Consider black holes: Einstein’s theory of general relativity — which provides an alternative explanation of gravity as a property of space and time — anticipated that when a massive star dies, the remnant it casts off has three times the mass of the Sun, and a black hole is produced.

Peet gave an alternative definition of the phenomenon: “an object is called a black hole if it is dense enough to be contained within its own event horizon.”

The event horizon can be thought of as the point-of-no-return: if you fall into it, escape is impossible, regardless of your rocket power. This also applies to light. Inside this radius, the gravity is so strong that not even light can escape.

Yet despite their attractive force, black holes still emit radiation

Peet mentioned that “at [a black hole’s] heart, there exists a singularity, where its curvature becomes infinite.” With an infinite radius, Einstein’s theory of general relativity fails to demonstrate any results at the singularity of a black hole, since all the equations render infinity as the solution.

Meanwhile, with the employment of quantum theory into Einstein’s theory of general relativity, physicist Stephen Hawking was able to prove that black holes actually do emit radiation — therefore they do not appear completely black after all.

Two theories that cannot exist under the same roof

Einstein’s theory of general relativity describes the physics behind very heavy objects — such as planets, stars, and moons. Quantum mechanics, on the other hand, is the physics relating to extremely small particles.

Now, considering the two, you would think that their incompatibility is not truly problematic, since nothing can be both very heavy and very small. However, when has science ever been that simple?

“There are two things that we care about: black holes and the Big Bang!” added Peet. They continued by saying that in order to be able to effectively and accurately analyze these two mysteries, we would need a theory that could be applied to both massive and small objects.

String theory mends the two clashing theories

String theory predicts that inside the elementary particles — irreducible particles previously thought to be point-like — are actually one-dimensional vibrating strands of energy known as strings. The fact that strings are versatile demonstrates the ease with which they can interact, and thus solves the problems arising from the theory of general relativity.

Peet also mentioned that string theory can predict possible extra dimensions of space, explaining that “the strings could wrap around those hidden dimensions.”

Multiple worlds at once?

Now that we have reached a better understanding of black holes, let us consider other realms and dimensions through our understanding of quantum theory. In 1935, physicist Erwin Schrödinger came up with a world-changing theoretical experiment known as the Schrödinger’s cat paradox.

“He placed a cat in a steel chamber with a Geiger counter, a vial of poison, a hammer, and some radioactive substance,” explained Brodutch.

This process is not one that naturally comes to mind, yet it does make physical sense. With the decay of the radioactive substance, the Geiger counter would prompt the hammer to fall on the vial, releasing the poison and consequently killing the cat. Seems pretty straight forward, right? Then, what is the paradox about?

What Schrödinger wanted to demonstrate, explained Brodutch, was that we would not know whether the cat was dead or alive until we opened the chamber. Thus, in order to be theoretically accurate, we would have to assume that while the steel box is still closed, the cat is both dead and alive simultaneously in two different worlds.

With the help of the Schrödinger’s cat paradox, we are able to somewhat understand the possibility of the existence of more than a single world at once.

The worlds can interfere

This paradox was employed in order to account for the wave function of a particle: the particle could be in any allowed position at a certain instant, yet you could not know exactly where unless you directly saw it.

Brodutch further said that “each world will be one term in the equation, and as the branched worlds keep going, the equation becomes longer and longer.”

Thus, maintaining control over these quantum systems becomes the main concern. Applying quantum theory to modern-day technological advances, Brodutch explained that it enables quantum computers “to factorize really, really fast,” and as a result, “keep [security-sensitive] transactions very secure.”

Physics has a diversity problem

An age-old issue brought back to life following Jocelyn Bell Burnell’s Breakthrough Prize award

Physics has a diversity problem

The Breakthrough Prize — a $3 million award bestowed to researchers in Life Sciences, Fundamental Physics, and Mathematics — recently recognized astrophysicist Jocelyn Bell Burnell for her discovery of pulsars.

When Bell Burnell was a researcher at the University of Cambridge in 1967, she noticed a signal that repeated every second or so through a radio telescope. Bell Burnell and her advisor Antony Hewish weren’t sure what to make of it.

These signals turned out to be pulsars, or fast spinning neutron stars that emit electromagnetic radiation. 

Though Bell Burnell was the first to discover pulsars, the Nobel Prize in Physics was awarded to Hewish and his colleague Martin Ryle in 1974.

Bell Burnell’s receipt of the Breakthrough Prize is historically significant, as women have not traditionally blazed through male-dominated fields like physics. When Bell Burnell came to Calgary on September 19, she told CBC News that the prize money would go to supporting underrepresented graduate students in science.

Though attitudes toward women in math and science have changed since the 1960s, there is still progress to be made.

According to U of T’s Professor AW Peet in the Department of Physics, one reason could be that social and cultural aspects cause participation rates in math and science to vary from country to country.

Many Eurocentric countries like Canada, the US, and the UK, have, in fact, lower participation rates of women in math and science compared to countries like Lebanon or Iran.

Eight per cent of the physics faculty in US universities with PhD-granting departments have no representation of women.

The statistics in Toronto aren’t promising either.

Of 14 faculty members who teach subjects relating to physics at UTM, only one is female.

While the University of Toronto has seen a significant improvement in female representation in physics, the number of female graduate and undergraduate students still remains low compared to women in biology or chemistry.

In 2012, 24 per cent of undergraduate students enrolled in Applied Science & Engineering, which includes studies in physics, were female. Of graduate students in the faculty, 26 per cent were female. 

These statistics have improved after five years. In 2017, 33 per cent of undergraduate students enrolled in Applied Science & Engineering programs were female; of graduate students, 27 per cent were female.

In contrast, 65 per cent of students pursuing undergraduate Biological Sciences and 57 per cent of students pursuing graduate studies in Biological Sciences were female in 2017.

These statistics do not account for students who identify as nonbinary, and though they reflect an improvement in female participation in the sciences, particularly physics, they are still worrisome.

Organizations like the International Union of Pure and Applied Physics have brought  delegations from different countries together to compare representation in physics and become more cognizant of representation in physics.

Moreover, in Canada, the Canadian Association of Physicists (CAP) has taken initiatives to narrow the gap.

One of its initiatives, according to Peet, who is also the former Chair of CAP, is an annual conference for women in physics known as the Canadian Conference for Undergraduate Women in Physics.

However, if real progress is to be made in the sciences, changes at the institutional level, like promoting women into roles such as Canada Research Chairs, and at societal levels, like providing better support for women on maternity leave, are crucial.

Farewell, Professor Hawking

U of T remembers the renowned astrophysicist

Farewell, Professor Hawking

I first learned of Dr. Stephen Hawking from Star Trek: The Next Generation. The episode originally aired in 1993, this brief foray on screen saw Hawking playing poker with Einstein, Newton, and android Lieutenant Commander Data. Physics jokes were made, Hawking won the hand, and the cameo was over.

Given the endless index of extraordinary events that made up Hawking’s incredible life, which came to a sombre end this March 14, I could have easily chosen a more important event to begin this tribute, but I chose this memory because I remembered my precise childhood reaction to that scene: ‘I have no idea who this person is, but if he’s next to Einstein and Newton, he must be awesome.’

I strongly believe that that cameo will prove prophetic, and that Hawking will be remembered with the likes of Einstein and Newton.

An extraordinary mind, he made great strides working on the fundamental problem of physics: finding a unified theory to reconcile the vastly differing physics of the small, quantum mechanics, with the physics of the large, relativity. Along the way, he revolutionized astrophysics and cosmology with a plethora of theories, including the much-lauded Hawking radiation.

“Stephen combined Einstein’s general relativity of spacetime with quantum mechanics, two of the biggest developments in physics in the first half of the 20th century, to investigate the basic laws which govern the universe,” wrote Dr. AW Peet, a professor in the Department of Physics and a 25-year acquaintance of Hawking, in an email to The Varsity.

“He discovered Hawking Radiation, showing that black holes are not completely black: they can emit weak radiation and eventually evaporate completely. His Black Hole Information Paradox posed over forty years ago is still a very active field of research today,” continued Peet.

Dr. J. Richard Bond, a professor at the Canadian Institute for Theoretical Astrophysics, also noted Hawking’s ubiquity in cosmology.

“Everything I have been working on lately on sabbatical at Stanford has had Hawking discussion arising about it: Hawking temperature, Gibbons-Hawking entropy, black hole evaporation, [and] wave function of the universe,” said Bond.

It is clear that Hawking’s brilliance cannot be overstated. Yet it wasn’t just his brilliance that netted his multiple television cameos, and it likewise is not only for his astrophysical acuity that the world mourns him today. Of equal measure to his mind was his incredible capacity to convey the most complex of ideas to a general audience in a humourous, straightforward, and engaging way.

“People whom I clearly recall coming up to me at cocktail parties to explain, with satisfaction, that they never could do chemistry, decided, instead, that their lives would be incomplete if they did not encounter Stephen Hawking. They were right,” said Nobel laureate Dr. John Polanyi, University Professor in U of T’s Department of Chemistry.

Polanyi made that statement 20 years ago, addressing a packed Convocation Hall, when Hawking came to visit U of T in April 1998. It carries no flippant embellishment.

With his popular science book A Brief History of Time selling more than 10 million copies since its publication in 1988, it is no exaggeration to say that Hawking has inspired generations of scientists.

At one end of the spectrum are long-time physicists like Peet.

“I first met Stephen in 1992 when I was a baby Ph.D. student, at a dinner party of theoretical physicists at Stanford,” wrote Peet. “I was inspired to work on the research topics I investigate partly by his deep theoretical physics insights.”

Hawking’s following only grew in the twenty-first century, rousing another wave of young scientists to explore the universe.

“I remember reading A Brief History of Time during my days as an undergrad,” recalled Matt Young, a PhD student in the Dunlap Institute for Astronomy & Astrophysics. “Instead of coming across as a dry lecture, the book told the story of the universe and all its fascinating physics at a level that was accessible by everyone.”

Even after his death, Hawking’s mammoth influence in the field continues to generate enthusiasm in the next generation of physicists.

“I still have my own well-worn copy of A Brief History of Time on my bookshelf from days of old,” said second-year Physics and Philosophy student Patrick Fraser. “It was arguably that introduction to physics that inspired my own journey, hoping to one day be a physicist myself.”

Although a physicist and cosmologist, Hawking always sought to promote not just a single field, but the attitude and spirit of science in general. Having worked tirelessly in his promotion of rational thought and public involvement in research, it is not only students of physics who answered his call.

“[He was] truly an inspiration,” said second-year Electrical and Computer Engineering student Tobias Rozario. “A Brief History of Time helped develop my passion in physics and engineering.”

Second-year Molecular Genetics and Biochemistry student Matthew Gene expressed similar sentiments. “Stephen Hawking was an inspiration to all — not just in his work, but also in the way he lived. Despite being diagnosed with a terminal disease, Hawking fought on, continuing to be… one of the most recognisable public faces in science. As a student in the Life Sciences, it’s the resolve of men like Hawking that makes me dream of a better future for medicine and humanity.”

Yet among the multitude of thoughtful sentiments, there is one fact that remains to be mentioned: the inevitable image of Hawking speaking in the familiar programmed voice of his omnipresent wheelchair. Fraser succinctly addresses this elephant in the room.

“It is true that he was a great scientist despite his physical limitations. However, what many people perhaps fail to realize is that he was a great scientist, period,” said Fraser.

Although iconic, Hawking’s amyotrophic lateral sclerosis is not what society should focus on when remembering him. Instead, we should remember one of the greatest minds of the twentieth and twenty-first centuries, who grappled with problems about the very underpinnings of the universe and left an academic legacy for the aeons.

We should remember a brilliant writer and unmistakable orator, who used his astonishing talent for communication to promote a better future for all of humankind.

We should remember, perhaps above all, an unbreakable human spirit, who once, in the words of Peet, “unexpectedly sped off down the steep driveway… for fun, with a huge grin on his face, enjoying the apparent consternation on the faces of non-disabled folks around him.”

Hawking — a Companion of Honour, Commander of the Order of the British Empire, Fellow of the Royal Society, Fellow of the Royal Society of Arts, and former Lucasian Professor of Mathematics — is an essential contradiction in the world. He was unable to physically perform and partake in so much that society fundamentally associates with humanity, yet one would be hard-pressed to find someone who lived a fuller life than Stephen Hawking.


“To have been on the leading edge of physics with such a disease over so many decades has to be one of the greatest triumphs of human will in the history of humankind. His life was a celebration of human spirit.”

— Dr. J. Richard Bond, Canadian Institute for Theoretical Astrophysics

“Always he insisted [that] mankind stop its pursuit of insane weaponry, hinting that our imaginations had become paralyzed. He will be remembered for centuries.”

— Dr. John Polanyi, Nobel Chemistry laureate, Department of Chemistry

“Stephen was a brilliant mind, a phenomenal researcher, a truly extraordinary scientist. He also had a magnificent sense of humour. For example, he once famously drove over Prince Charles’s foot while showing him some wheelchair tricks. Don’t refer to Stephen as “wheelchair bound” or “suffering from” ALS/motor neurone disease or other pity-based words to describe disability. His wheelchair and robot voice system didn’t constrain him – instead, they liberated him.”

— Dr. AW Peet, Department of Physics

“I think Stephen Hawking will be remembered with the likes of Newton [and] Einstein, people that revolutionised their fields and dedicated their lives to understanding the world around us. Much of [today’s] research on topics such as black holes is directly building on Hawking’s contribution to science.”

— Matt Young, PhD student, Dunlap Institute for Astronomy & Astrophysics

“The sheer magnitude of his accomplishments in the field was astounding, entirely irrespective of the difficulties of his daily life… In the history of science, [his] academic achievements have been matched by few… He will be missed, but his legacy will live on.”

— Patrick Fraser, Physics and Philosophy specialist student

“His death caught me off guard. I never really expected him to die. Much like the Queen, I saw him as a staple of culture that just ‘exists.’”

— Daniel Wardzinski, Computer Science major, Mathematics and Philosophy double minor student

“He showed me that success comes from how you think and not what people think of you. I guess a lot of people measure how successful they are by how people look at them, but Hawking didn’t care about that.”

— Jenoshan Sivakumar, Astrophysics specialist student

“His collaborations with his daughter Lucy Hawking to write children’s books on space and science were incredibly influential on my childhood. They played a part in why I decided to learn physics.”

— Abhinav Bhargava, Physics and Philosophy specialist student

“Great scientists are rare, and great explainers are possibly even rarer. But in [A Brief History of Time], Stephen Hawking wrote about complicated concepts so well that they seemed almost intuitive.”

— Cameron Davies, Mathematics specialist, Ethics, Society, and Law major student

“Dr. Hawking was a genius and a pioneer in physics, but what was most inspiring about him was his pursuit of passion and of life in the face of adversity.”

— Hansen Jiang, Astrophysics specialist, Computer Science minor student

“It’s safe to say that Stephen Hawking is half the reason we’re here. He inspired an entire generation to look to the stars and imagine the unimaginable. To say he’ll be missed would be a drastic understatement.”

— U of T Astronomy & Space Exploration Society

Ripples in spacetime found to be physical

Smashing ‘gravitational waves’ detection turns 100-year-old theory into fact

Exactly 100 years ago this month, Albert Einstein first proposed his theory of general relativity. Just over a week ago physicists announced that the theory has finally been confirmed.

Einstein’s ground-breaking theory predicted, amongst other things, that the acceleration of massive objects would cause ripples, called gravitational waves, which move through the fundamental backdrop of the universe, much in the same way that regular water waves may ripple in a cup of coffee. Whereas the ripples in your drink may be caused by the act of dropping a cube of sugar into your mug, these gravitational waves were successfully detected from the merging of two black holes over a billion light-years away.

Physicist David Reitze began the announcement bluntly, “Ladies and gentlemen, we have detected gravitational waves.” His words were met with jubilance at the Washington D.C. press conference, as he paused to let the significance of a century’s worth of painstaking effort to resonate among the audience.

At the University of Toronto’s Canadian Institute for Theoretical Astrophysics’ (CITA) webcast viewing event, which took place at the Burton Tower of the McLennan Physical Laboratories, the applause was only outdone by the radiant smiles that were shared among members of our own physics department.

“It’s momentous,” said Luis Lehner of the Perimeter Institute for Theoretical Physics in Waterloo. “It marks the beginning of our ability to peek at the universe through a completely new window.”

Gravitational waves are created by powerful events, like a binary black hole merging. Black holes are some of the densest and heaviest objects in the universe, with some having masses four million times greater than our sun. When these massive objects collide, they release a large burst of energy in a short amount of time. This energy is dispersed via ripples that travel throughout the entire universe. As gravitational waves travel, they compress space in one direction while stretching it in the other, a phenomena that scientists believed they could identify.

Over large distances however, gravitational waves usually fade as their energy dissipates, turning into no more than a whisper, leading scientists to fear that they would never be able to detect their existence. In this case, however, the energy released by the black hole collision was so great that its gravitational waves were able to remain detectable after travelling over a billion light-years to Earth.

Determined to detect gravitational waves, the U.S. National Science Foundation (NSF) invested more than $1.1 billion (US) into the construction of the Laser Interferometer Gravitational-wave Observatory (LIGO), which is described as “the most precise measuring device ever built.”

LIGO is comprised of two separate detectors, one in Livingston, Louisiana and one in Hanford, Washington. The detectors were designed around the concept of gravitational waves compressing space in one direction and expanding it in the other.

LIGO’s first observational run began in 2002 and ended in 2010 without having detected any gravitational waves. The NSF remained confident however, and a major upgrade was made to the detectors, making LIGO more sensitive. As it turns out this was a brilliant decision because the signal was only just quiet enough to have evaded detection before LIGO’s recent upgrade.

Each detector is made of two four-kilometre long perpendicular arms that have ultrapure glass mirrors at their ends. A beam of light is split into two and shot down both tubes, bouncing off the mirrors and returning to the starting point. LIGO is able to detect gravitational waves by measuring miniscule differences between the journeys of the two beams — if nothing interferes with the beams, their recombining will cancel each other out.

A light sensor is waiting in case something changes. Because of the perpendicular arms, the single dimension compression and stretching caused by gravitational waves will compress only one arm and stretch the other. So if a gravitational wave warps the path of one of the lasers, the two beams will be marginally misaligned, and the laser will hit the photodetector, alerting scientists to the deformity.

1.3 billion years ago, in a galaxy far far away, a pair of black holes were circling each other, slowly spiraling inwards, until they merged into one massive black hole. The two black holes had the equivalent weight of 36 and 29 times that of our sun respectively — much larger than most black holes, which typically have a mass equal to about ten times our sun. At the time of the collision, scientists estimate that they orbited each other at an astounding rate of 75 orbits per second.

The resulting black hole, however, was not the 65 solar masses one would expect from addition, but rather 62. This collision resulted in the mass of about three suns being converted to energy and released in a fraction of a second, which gave rise to particularly turbulent gravitational waves.

That wave first reached the LIGO facility in Louisiana, followed by the one in Washington state just seven milliseconds later. This allowed physicists to locate the black-hole collision as having occurred somewhere in the southern sky. The tiny time delay in itself proved that gravitational waves move at the speed of light.

As well as confirming a century-old theory, the detection of gravity waves may also have a practical application that can help us uncover more secrets of the universe. Until now scientists have relied on light to observe the cosmos, but if we can find a way to design telescopes that use gravitational waves, we may be able to probe into parts of the universe where even light cannot reach and drastically increase our observational field.

Such ‘Einstein telescopes’ could potentially track black-hole mergers, identify the collisions of ultra-dense neutron stars, investigate exploding stars and unearth theoretical “cosmic strings” left over from the big bang. Gravitational waves will give scientists an identifiable marker for when objects don’t emit visible light.

Scientists from the California Institute of Technology and the Massachusetts Institute of Technology have led the project, supported by a variety of international scientists and institutions. In fact, the scientific paper published names 1,004 individual authors.

The members of the LIGO Scientific Collaboration based at the University of Toronto include Harald Pfeiffer, Prayush Kumar, Kipp Cannon and Heather Fong, a physics graduate student. CITA researchers contributed to the search pipelines that identified the black hole merging and the theoretical waveforms that established the black hole masses and spins.

With this new discovery, we are one step closer to peering further into the final frontier and understanding where our universe came from.