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Gravitational Wave Observatories Open New Era in Astronomy

Teams report detection of neutron-star merger along with optical and gamma-ray signals

Following closely the announcement of the 2017 Nobel Prize in Physics, the LIGO and Virgo collaborations reported on October 16 in Physical Review Letters that they have detected the coalescence of two neutron stars — objects of lower mass and much different in character from the black holes in the previously observed mergers. Moreover, reports from about 70 ground — and space-based observatories confirm that a variety of electromagnetic signals — from gamma rays to radio waves — was detected as well.


Map of the sky showing gravitational wave detections. GW170817 is the most recent and was correlated with electromagnetic signals observed by around 70 ground- and space-based telescopes.

The gravitational wave signal, denoted GW170817, was first observed by LIGO and Virgo on August 17. Researchers concluded that the inspiraling objects were in the range of 1.1 to 1.6 times the mass of the Sun, and thus were unlikely to be black holes. This mass range corresponds to that of neutron stars, typically formed in the aftermath of supernova explosions. The data indicated that the neutron-star merger took place some 130 million light years from Earth.

Black-hole mergers are expected to produce no electromagnetic signals, as these photons could not escape the grip of gravity. Neutron-star collisions, however, could yield bright flashes across the electromagnetic spectrum. And indeed, a gamma-ray burst was detected by NASA’s Fermi spacecraft and confirmed by the European Space Agency’s INTEGRAL space-borne detectors.

The coordinates for the origin of the signal corroborated those from the LIGO/Virgo data. Soon, follow-up observations by other telescopes revealed emissions at various wavelengths. These results helped identify the merger as located in galaxy NGC 4993 in the Hydra Constellation.

“This detection opens the window of a long-awaited ‘multi-messenger’ astronomy,” said Caltech’s David H. Reitze, executive director of the LIGO Laboratory, in a press statement. “It’s the first time that we’ve observed a cataclysmic astrophysical event in both gravitational waves and electromagnetic waves — our cosmic messengers. Gravitational-wave astronomy offers new opportunities to understand the properties of neutron stars in ways that just can’t be achieved with electromagnetic astronomy alone.”

The Other End of the Stethoscope


I receive a call from my father. His voice heavy and calm, he says my name as I pick up the phone. Am I someplace where I can talk? There is news, unfortunately. A mass. He speaks with the same quiet reserve and scientific openness to the fact that have made him a good physician. There is courage, I think, in his maintenance of this stance, even as he finds himself on the other end of the stethoscope. The surgeon has already called. His name is Master. It calms my father to know that Dr. Master advises the World Health Organization on renal cancer. They will meet tomorrow. I bite my lip through the call, not wanting to burden him with my own fear, my own sorrow at the thought of losing the man on the other end of the line.

My mother calls from the OR waiting room. She is pleased to tell me that Papa, as our family calls her father, trained the anesthesiologist. I find myself soothed by this idea as well: my grandfather, the difficult man partly responsible for my father’s decision to go into academic medicine, resurrected after an untimely death in the form of my father’s anesthesiologist. I board the plane.

The air in Atlanta is warmer than the air I left behind in New York. As I enter my father’s room, he sees me first. My mother is asleep in the chair beside him. He pulls me close, holds my head to his chest for a long time. He is still groggy, not long post-op, but he wants to show me his scars. He lifts his gown with pride to reveal three small holes, one for each trocar, and a large incision in the midline.

At 3 a.m., I awake uncomfortably in the chair beside him to the squeaky wheels of the phlebotomy cart. At its helm is a tiny woman cloaked in headscarf and accent and night. Anonymous, ageless, she is a gentle ambassador from a faraway place, destined to wander dim halls into dark rooms to draw the blood of the sick of this place. “You’ve done this before,” he tells her. I hear her smile in the darkness.

In the morning, the residents are nervous, untucked, their confidence and unquestioned authority unsettled by the presence of a senior member of the medical faculty in the bed before them. When Master arrives, he is crisp, pressed, and clean, deep blue suit pants beneath his white coat. My father is in the chair now. Master asks to sit on his bed. A foot below my father, he looks up at him to ask how he’s feeling. He proceeds to cite four articles in 5 minutes, one on the benefits of ice after abdominal surgery, another on postnephrectomy kidney function. He wants the same thing from my father that the residents did, but he is better equipped to get it. When he leaves, my father turns to me,
wants to know if I caught that — how Master sat below him on the bed, approached from below to put him at ease.

Later I return from the cafeteria to the sound of my father’s voice. He is on the phone with his nurse’s aide, calls her by name. He wonders if she’s free to take a walk, he says. Of all the people on the floor, he has connected most with her, the lowest paid member of the team, with the least training. By a twist, she is the one least afraid of him. “They told me you would be trouble because you’re a doctor,” she tells him when she reaches
his room, “but you’re OK.” They walk slowly, IV pole in tow. She insists he holds the wooden railing while she remains firmly at his other side. The first lap is enough. But he is ready again an hour later. Two laps, then four.

At first, I walk with them, but then I leave them to it. I catch snippets of their conversation as they pass his room. She hopes to go into speech pathology if she can afford the training. “You’ll be good at that,” he tells her. He begins to push himself to break his own record, a moving goalpost scrawled on the whiteboard in his room with the green erasable marker. Twenty laps to a mile. Thirty laps. Forty laps. Home.

My father is back at work. His scans are clear 3 years out. I am now in my fourth year of medical school. As I walk the halls of my hospital, I often think of those nights I spent with him in his. I think, too, about what I’m looking for in medicine. I enjoy the dynamic

Of all the people on the floor, my father
has connected most with his nurse’s aide,
the lowest-paid member of the team,
with the least training. By a twist,
she is the one least afraid of him.

strength of its methods — the double edge of its empiricism — which damns it to abandon its most sacred truths as soon as still holier evidence comes to light. But I know that I am here for something loftier than a certain methodology and the mechanisms it illuminates. I want to find, somewhere in the depth of a fluorescent light or the stillness of a linoleum day, some understanding of life and death, my own life, my own death, your life and your death. I believe I have come to medicine looking for some kind of peace and some kind of purpose. I do wonder whether it lives here. What I believe my father showed me — as he was learning to be a patient for the first time in a life full of patients — is that it does.



Disclosure forms provided by the author are available at NEJM.org.
From Columbia College of Physicians and Surgeons, New York.
DOI: 10.1056/NEJMp1707514
Copyright © 2017 Massachusetts Medical Society.