For nuclear physics graduate student Chelsea Bartram, White House adviser Kellyanne Conway's "alternative facts" were the last straw.
President Donald Trump had disputed photographic evidence of the size of his inauguration crowd. Reporters challenged him. Conway's response — that the administration gave "alternative facts" — has become a widely used hashtag for anything demonstrably untrue.
"A lot of us do care about this notion of an objective reality,"said Bartram, who is pursuing a doctorate at the University of North Carolina at Chapel Hill.
"Many scientists I know, myself included, spend so many hours in the lab sacrificing enormous amounts of their life for this abstract idea" that understanding reality can benefit human civilization, she said. "And then to have someone say, 'Well, that's not important anymore,' it's so devastating."
So on Saturday, Bartram plans to join the March for Science, a protest in Washington and more than 500 other cities around the world supporting science's role in government decisions on health, safety, the economy and more.
The march has more than 200 co-sponsors, including many major scientific and professional societies, zoos, aquaria and advocacy groups. Organizers have not released crowd size estimates.
"This is pretty remarkable and unprecedented," said geochemist Eric Davidson, president of the 60,000-member American Geophysical Union, one of the march co-sponsors. Many of the group's members did the climate research that the Trump administration disavows.
"I can't think of another example where scientists have organized themselves in as many cities with an event as big as this," he said.
The dispute over crowd sizes was just one small example of what scientists see as a larger pattern. During the campaign, Trump dismissed the scientific consensus about the dangers of human-induced climate change. His appointee to lead the Environmental Protection Agency, Scott Pruitt, also does not accept climate science. He has repeatedly clashed with the agency he now heads.
But scientists say their frustration has been building for decades.
"We might have reached a tipping point now, but acting as though this is a new thing is giving too much credit to the current administration," said march co-organizer and public health expert Caroline Weinberg. "It's letting people who have been there for a very long time off the hook."
And it goes far beyond climate change, Weinberg added. "It's about not paying attention to the best research on things like food stamps. It's about cutting things like Head Start and after-school programs," to name a few. "And that all affects health, because that's a time to set kids on the right path."
Critics say a public protest risks further politicizing science, turning scientists into just another interest group.
Bartram sums up a widespread response: on hot-button issues like climate change, opponents have already done it. "I don't think anything we do is going to further politicize it," she said.
But if the goal is to get policymakers to listen, "a march isn't going to change anything. That's the problem," said Rob Young, head of coastal research at Western Carolina University.
Young said much of the problem stems from the growing disconnect between scientists and voters, especially the rural and working-class people who voted for Trump. He said most probably have never met a scientist.
"It's easy to demonize us if those folks don't know who we are," he added.
Scientists need to get out of the lab more, he said, and explain how their work affects people's health and livelihoods.
"I hope that when they're done marching in Washington, that they will come home and that they will march into their local planning board or local town council," he concluded.
That's what march organizers hope, too. Many scientists accept much of the blame for the disconnect with voters.
The American Geophysical Union's Davidson said a major post-march goal is more public engagement. "I think the day is gone when scientists can stay in their ivory towers and assume that everyone is going to recognize their value," he added.