CAMBRIDGE, Massachusetts — On the last day of Harvard astronomy professor Avi Loeb’s course for first-year students, he posed two questions to the class.
If a spaceship landed on Earth and some friendly aliens offered you a one-way ticket to join them into outer space, would you take them up on it? And if you had a chance to travel into a black hole with no prospects for survival, would you accept?
The black hole question received few takers among students “unless it was their final hour,” said Loeb, who is the chair of the Harvard astronomy department.
But to his surprise, many in the class would “take the ride with the aliens as long as they could share it on social media with friends,” he recalled.
“It was very strange,” he said. “Who cares about social media when you’re surrounded by aliens?”
These may seem like hypothetical questions, but Loeb is working to bring the scenarios closer to reality. A globally recognized and respected scientist who grew up on a small moshav (communal village) near Tel Aviv, Loeb says that two interstellar objects have entered our solar system in the last five years — a meteor in 2014 and a much larger, pancake-shaped object termed ‘Oumuamua, (Hawaiian for “traveler”) in 2017. These represent the first two times humanity has ever recorded interstellar objects, he claims, adding that similar objects could act as vessels transporting life from other solar systems to ours.
“Maybe the most important scientific question that can be asked is, ‘Are we alone?’” he told The Times of Israel during an interview at his campus office.
Were life to be discovered elsewhere in the universe, either primitive or intelligent, Loeb said, “I think the effect on our civilization would be dramatic. It would change our perception of our place in the world and lead to new areas of study and research in almost everything we do.”
Maybe the most important scientific question that can be asked is, ‘Are we alone?’
When he’s not jolting science with his personal research, Loeb leads and participates in groundbreaking group endeavors such as the Harvard-based Black Hole Initiative, of which he is the founding director. In April, scientists from the initiative participated in the analysis of the first recorded images of a black hole, captured by the Event Horizon Telescope and featured on the front page of newspapers worldwide.
These are heady days for Loeb, yet he describes himself as the same outside-the-box thinker he’s always been, going back to his days as an Israeli youth collecting eggs on a farm and considering a career in philosophy. Yet even back then, there was another constant to Loeb’s life: He could not stop looking up at the sky.
Looking up, right out of the box
The sky was hardly visible on an overcast afternoon in May when Loeb sat down for a chat at the Harvard-Smithsonian Center for Astrophysics.
Formerly known as the Harvard College Observatory, the center’s past visitors include Albert Einstein, who posited the existence of black holes in his 1916 theory of relativity. The Einstein Tea Room commemorates the famed scientist’s visit.
One of the center’s current projects is digitizing the research of female volunteers who researched vital astronomical data there in the 19th and 20th centuries. They included Cecilia Payne-Gaposchkin, who became the first individual to receive a PhD in astronomy from Harvard for finding that the sun’s atmosphere is composed largely of hydrogen, contradicting the era’s mainstream view.
In general, scientists must be unafraid to challenge mainstream thinking, Loeb said, even if it generates criticism.
“People should be open-minded,” he said. “It took me a while [to develop] a thick enough skin… I have some leadership roles, but I don’t need that assurance. I trust my gut instinct. I’ve never had too much backlash.”
Yet sometimes Loeb’s research sparks debates as intense as any tennis match on the courts outside his office. When he postulated that the 100-meter-long (328 feet) ‘Oumuamua might be an alien probe, or space debris from an extraterrestrial civilization, colleagues countered that it could be a comet instead. A new paper published July 1 in the prestigious journal Nature Astronomy hypothesizes that ‘Oumuamua is a purely natural phenomenon. Similar to the idea that Jupiter created the Oort cloud on the edge of our solar system, the interstellar asteroid was in a system with a gas giant planet orbiting a star and the orbit could have ejected ‘Oumuamua.
“As the first interstellar visitor to our Solar System, ‘Oumuamua has challenged many of our assumptions about how small bodies from another star system would look. While ‘Oumuamua presents a number of compelling questions, we have shown that each can be answered by assuming ‘Oumuamua to be a natural object,” wrote the article’s authors.
In a response email to The Times of Israel, Loeb wrote that there is “no new scientific evidence in this paper,” calling it “an opinion essay” whose conclusions were refuted by his previous publications on ‘Oumuamua as well as by a Cornell University paper by Zdènek Sekanina published in May.
A separate back-and-forth volley with mainstream scientific opinion involved another possible interstellar object. This time, things went all the way to the White House and Los Alamos before being resolved to Loeb’s satisfaction.
It began earlier this year, when Loeb and his Harvard undergraduate assistant, Amir Siraj, were examining public data from the United States military regarding worldwide meteor impacts over the past 30 years. One in particular caught their attention — a meter-length (3.28 feet) object that burned up over Papua New Guinea on January 8, 2014.
At 60 kilometers per second (37 miles), it was traveling fast enough to have originated outside our solar system, Loeb said. It would represent the first interstellar object ever recorded, predating ‘Oumuamua by almost four years.
Just where exactly the meteor originated from intrigues Loeb. He posits that there are “habitable regions around deep space,” planets with liquid water where life might develop, and is fascinated by the theory of panspermia, which hypothesizes that life can be transferred by meteors from one solar system to another.
Loeb notes that for life within a meteor to survive, “you need a bigger object.” However, larger meteors are rarer, “one per series of gigayears, billions of years,” he said. Yet such a meteor could “seed Earth with life everywhere,” according to Loeb.
As for the smaller meteor tracked by the US military, there was a problem: Its data had not been fully declassified. Notably, Loeb said, the military did not disclose error bars, or measurements of uncertainty. While recognizing the national security considerations involved, he issued a plea for more information from “people that might know, just for this object, at least the minimum, whether it was bound or unbound to the sun.”
Several weeks after speaking with The Times of Israel, Loeb ended up finding the information he sought thanks to two officials at Los Alamos: Alan Hurd of the laboratory’s National Security Information Center, and Matt Heavner, the data science program manager of Los Alamos’s Global Security, Intelligence & Emerging Threats division. Further aided by the White House’s Office of Science and Technology Policy, Loeb ultimately learned the degree of uncertainty in calculating the meteor’s speed from the individual who had analyzed it in 2014.
“[The] declassified error bar implied that the meteor arrived from interstellar space with a statistical confidence of 99.999 [percent],” Loeb wrote in a paper dated June 4, adding that this vindicated him from the criticism of colleagues whose experience was “that novel results are rare and that conservatism is a safe approach for avoiding mistakes and maintaining a good reputation.”
Holistic look into black holes
Loeb is not always a lone wolf battling the pack. He says that teams can work well in science. As an example, he cites the Black Hole Initiative, which he describes as unique in two ways — it is the only research center dedicated to the study of black holes, and it does so through a multidisciplinary approach incorporating philosophy and mathematics in addition to astronomy and physics. He calls its work crucial to the international effort to record the first-ever image of a black hole from the Messier 87 (M87) galaxy. The Event Horizon Telescope achieved the undertaking in April.
When Loeb started his career in science 30 years ago, “most astronomers worked on their own, or on very small teams,” he said, whereas the EHT now represents “hundreds of people… around the globe, using the entire Earth as a big telescope, with aperture stations on different continents.”
“It’s a new era,” he said.
Yet Loeb recalls a previous team effort that inspired him as a 7-year-old: the moon landing of Apollo 11 on July 20, 1969, which will mark its 50th anniversary this month. Loeb’s family was the first in their village to have a TV set and he remembers the excitement of that day.
While he never wanted to become an astronaut himself (and while he dislikes sci-fi for its defiance of the laws of physics), an interest in science stayed with him and brought him to the IDF’s prestigious Talpiyot program, then to faculty positions in the US, first at Princeton and now at Harvard. He has also become a husband and father.
The world is marking a half-century since the moon landings that fascinated Loeb as a youth. He laments the missed opportunities of the past decades — “over the past 50 years, there has not been another visionary space project,” he said. “I think the public is really hungry for that.”
Today there is a smorgasbord of such initiatives. Some are led by state governments, including the US and China. Others are privately-funded ventures such as the separate projects of billionaires Jeff Bezos and Elon Musk. Loeb followed the Israeli effort to land the satellite Beresheet on the moon earlier this year. Although Beresheet exploded after reaching the moon, Loeb praised the project in a televised Hebrew-media interview.
“I commented about it immediately after Bibi spoke,” he said, referring to Prime Minister Benjamin Netanyahu. “It’s a source of great pride in Israel, one of four nations to get to the moon and the first that’s done it through the private sector… I think it’s a great milestone, an important milestone, that Israel has done. It has the intellect, power and innovation to be a leader in space technology. I very much hope there will be a continuation of the project in this form. I’ll do my best to help them.”
Fifty years ago, when Neil Armstrong first set foot on the moon, he said, “That’s one small step for man, one giant leap for mankind.” Loeb is poised to help humanity make future giant leaps — including through the Breakthrough Starshot initiative, which hopes to take the “first step out of the solar system for our civilization,” he said.
He added, “I hope once we leave, we find a lot of traffic, and hear back from a solar system, ‘Welcome to the interstellar club.’”