The particle physicist was sitting at a cafe in Tel Aviv when a young waitress rushed over, gushing at her in admiration. An older couple, a husband and wife, at the next table looked over at her with tears in their eyes.
“You are our hope,” the wife said. Later, the physicist stopped to chat with the couple on her way out, and hugged the woman.
“She’s an honest, brave and genuine leader,” said the husband, Natan Sitner, a retiree. “She didn’t come to this out of personal interest,” Mr. Sitner said. “When she gets up onstage, everyone listens and believes what she says.”
For years, the physicist, Shikma Bressler, devoted herself to the lab she runs at a science institute near Tel Aviv, a job she describes as her passion, and to the raising of her five daughters in a small village in northern Israel, staying far away from politics.
But she has also become the face of the protests that have rocked Israel for months, marching on the streets of Tel Aviv on Saturday nights, exhorting crowds of protesters with speeches echoing with revolutionary ardor, and amplifying her message in a steady stream of social media posts. She was arrested, briefly, in March after she encouraged protesters to block a highway.
Dr. Bressler sealed her status as a symbol of the protest movement last month when she led a miles-long column of demonstrators on a multiday march to the hills of Jerusalem from coastal Tel Aviv. It evoked a biblical pilgrimage, and they picked up tens of thousands of supporters during the journey.
The march, Dr. Bressler said, was “almost a spiritual experience,” attracting Israelis angered by the government’s contentious plans to reduce the influence of the Supreme Court, a move that prompted perhaps the deepest internal crisis since the foundation of the state 75 years ago. People along the way contributed huge quantities of food for the marchers. Somebody noticed that one of Dr. Bressler’s shoes was torn and asked for her shoe size. She soon had seven pairs to choose from.
“It’s rare that you recognize you are in a real-time historical moment,” Dr. Bressler said during an interview in the cafe, reflecting on the events of the past few months. “It’s amazing to be living it as it happens and to be taking on some responsibility for this story.”
After the march from Tel Aviv, many of the demonstrators camped out near Parliament until lawmakers passed the first law last week in a package of legislation intended to rein in the Supreme Court and give more power to the government.
While the far-right and religiously conservative governing coalition that campaigned for the changes argues that they are a much-needed move to bolster the authority of elected governments, critics like Dr. Bressler see them as an effort to erode Israel’s democracy and worry that they could lead to a dictatorship.
“We are at a historical crossroads,” Dr. Bressler said in the interview, which was conducted a few days after the vote. “From here, there is no going back; we can only take one of two ways forward,” she added.
“We can either fall into a very dark, extreme, racist place where the Israel that we know, in all its social and economic aspects, will be destroyed,” she said, touching on another issue that has struck a nerve with liberal Israelis — the presence of ultranationalist ministers in the government with a history of anti-Arab incitement and homophobia. “Or we can build a new stronger, better democracy for the good of all the people.”
Dr. Bressler is a professor and runs a lab at the Weizmann Institute of Science in Rehovot, south of Tel Aviv. She is an active member of an international team experimenting with particle detectors at the Large Hadron Collider at CERN, near Geneva — an effort, she said, to understand “the other 95 percent of the universe beyond what we already know.”
She said she never planned to become a leader of the protests, and had no political ambitions.
“If I had wanted to be a politician, I’d have gone into politics,” she said.
Dr. Bressler said she first became concerned about where Israel was headed in March 2020, when Benjamin Netanyahu, then the prime minister, as he is now, ordered a shutdown of the courts at the start of a coronavirus-related lockdown. Mr. Netanyahu cited health concerns for the move, but it also postponed the opening of his corruption trial, angering many Israelis.
Dr. Bressler said she and two of her three brothers decided they had to do something.
They devised a plan to lead a convoy of cars driving to Parliament in Jerusalem, and made video clips calling on people to join them. Dr. Bressler’s clip circulated widely online, and scores of people turned up with their cars for the protest.
Encouraged by their success, Dr. Bressler and her siblings founded a group called Black Flags, one of the early anti-Netanyahu protest groups, and became actively involved in later protests that sought to oust the prime minister.
During the subsequent period when Mr. Netanyahu was out of office, from June 2021 until the end of 2022, Dr. Bressler settled back into her routine at the lab and at home — her elder daughter is now 17; the youngest, age 5, is still in kindergarten.
But she returned to the streets for a huge protest in Tel Aviv on Jan. 14, days after the justice minister, Yariv Levin, introduced his plan to overhaul the country’s judiciary.
The next Saturday night, the coordinating committee for a protest in Tel Aviv was seeking a presenter to go onstage and, after failing to recruit an actor or prominent journalist in time, decided to ask Dr. Bressler.
“Things evolved from week to week. It evolved until she became the face of the struggle,” Nadav Galon, a spokesman for the committee, said of Dr. Bressler.
She stays on message in her speeches and frequent appearances in the Israeli news media, using plain language to convey what she calls the urgent mission to “save the country.”
Today, Dr. Bressler is not associated with any particular protest group.
The antigovernment protest camp embraces a broad section of mainstream Israelis who want to preserve a more pluralist and liberal society. It has no hierarchical or formal leadership; a highly organized coordinating committee is made up mostly of volunteers. Financing comes from contributions from Israel’s business and tech communities and from crowdfunding.
Dr. Bressler said it was the nature of Israelis to respond when “called to the flag,” echoing the views of many Israelis that the protests are a patriotic struggle to protect a democracy at risk. A former basketball player, she spent her period of obligatory military service in a special track for outstanding athletes and lost several high school peers in the war between the Iran-backed Lebanese militant group Hezbollah and Israel in 2006. Now, she said, it was her turn on the front lines.
As well as celebrity, her activism has put her in the cross hairs of Mr. Netanyahu’s loyalists, who have branded the protesters as anarchists.
May Golan, the conservative minister for the advancement of the status of women, described Dr. Bressler as an agent of chaos. Tally Gotliv, an outspoken lawmaker from Mr. Netanyahu’s Likud party, said Dr. Bressler enjoyed “delusional fame based on lies.” She added that protest organizers who disrupt the lives of lawmakers “should be investigated by the police on suspicion of incitement.”
A self-described political centrist, Dr. Bressler acknowledges that the protest movement cannot solve all of Israel’s problems.
After the setback in Parliament last week, the organizing committee is focused on trying to maintain the momentum of the main Saturday night protests while Parliament is in a recess until October. Dr. Bressler said she found it “magical” that so many people kept showing up.
She was back on the stage at the big weekly protest in Tel Aviv on Saturday night, dressed in a T-shirt with a logo of a raised fist and the words, “We must resist.”
Addressing the crowd, she read her speech from her phone in one hand while holding a large Israeli flag in the other. Then she roared out the signature chant of the protest, “De-mo-cra-tia! De-mo-cra-tia!” A rapt audience of tens of thousands chanted back.