When he arrived at Brown University in August 2015, it was the first time Babak Hemmatian had ever left Iran. But he felt as comfortable among the school's brick buildings, tree-lined walks and lively students as anywhere he'd been.

“You can be totally yourself here,” he said. “You don’t have to lie about any of your beliefs, you don’t have to lie about any aspect of your lifestyle, and people will accept you nonetheless.”

Hemmatian, 25, is a PhD student in cognitive science, a beloved only son and a self-confessed nerd. But he's also gay. In Iran, his sexuality could get him jailed or even killed, so he kept it hidden. The visa that allowed him to travel to the United States for graduate school was a ticket to a different kind of life — an opportunity to be open about who he was.

But now it could all vanish. Under the executive order signed by President Trump last Friday, citizens of Iran and six other majority-Muslim countries are barred from entering the United States for at least 90 days. This includes people like Hemmatian who hold visas to study or work here.

As news of the ban broke, Hemmatian felt sick. The country that, for him, represented acceptance would now turn people like him away. Making matters worse, Hemmatian's father is battling stage four colon cancer and has only a slim chance of surviving until Hemmatian's graduation in three years. If the young man travels home to see his father one last time, he may not be allowed back to finish his degree.

Yet part of Hemmatian, the part that sees the world through a scientist's critical eye, knows the ban also illustrates why he is here.

Hemmatian came to the United States to study reasoning. He is interested in how categories are created, what makes beliefs take hold, why people are willing to accept stereotypes as fact. After graduating from the University of Tehran with a degree in clinical psychology, he couldn't find any Iranian researchers doing this work, so he applied for the PhD program at Brown.

“Think of when someone says something like, 'Why is he acting like this?' and someone else responds, 'Because he's a Republican,' or 'because he's a Muslim,'” Hemmatian said. “Those kinds of explanations can provide no information at all, and still, as long as those labels are used in the community, and the community considers those labels related to those qualities … people think they are perfectly good explanations.”

The text of the president's order says that its intent is to keep out visitors who might hold “hostile attitudes” toward this country or engage in “acts of bigotry” like oppression of people based on their religion, race, gender or sexual orientation. The impetus for the new policy is said to be recent terrorist attacks committed by foreign nationals, such as the 2015 shooting at a community center in San Bernardino, Calif.

But that description of visitors with “hostile attitudes” doesn't fit Hemmatian or, he said, most of the Iranians he knows. And based on the countries targeted — Iran, Iraq, Syria, Sudan, Libya, Yemen and Somalia — the ban itself wouldn't have prevented any of the deadly attacks by Islamic terrorists on U.S. soil in the past 16 years.

To Hemmatian, the immigration order is an example of labels — in this case, seven nationalities — being invoked without evidence that they're really relevant.

Research by Hemmatian and his adviser has shown that people use stereotypes to interpret situations about which they have only a shallow understanding. Asking them to explain their reasoning can begin to change attitudes.

“That's when most people realize they do not know as much as they thought they did,” he said. “And that leads to less extremism in their beliefs.”

Here is what Hemmatian wishes strangers knew about him.

He's in a serious relationship with a fellow graduate student, Graham. They met online, and from their very first date Hemmatian knew that this was someone he wanted to be with. Graham is serious, smart and sophisticated, Hemmatian said, laughing that “he has an even higher bar for movies than I do.” And his eyes don't glaze over when Hemmatian launches into one of his long-winded monologues about politics.

In Iran, same-sex relationships are cloaked in secrecy and burdened by the anxiety of being found out. Yet when Hemmatian visited Tehran last month and told his family he had found a partner, they were immediately accepting.

“What did you think? I realized you were dating him because you were talking with him nonstop every day,” his mother said. Hemmatian's sister wanted to buy Graham gifts. His father, a postal service employee who spends his free time translating Charles Dickens novels into Persian, wanted to talk with Graham about books.

“He told me I should invite Graham to Iran to come stay for a couple weeks,” Hemmatian said. “We also talked about plans for the opposite, for my parents to maybe visit in the summer and see Graham and see the East coast. … That doesn't seem like an option anymore.”

The travel ban comes as time is running out for his father. Hemmatian talks with his parents daily, trying to figure out what he will do if his father's condition worsens. And he's started calling his sister for updates as well, not trusting that his parents will keep him informed about their health.

“They think that I just shouldn’t risk my studies here,” he said. “That if I have to chose between visiting and finishing my studies, I should just stay here. But I don't think I can do that.”

Like thousands of other students from the seven countries who currently are in the United States, Hemmatian has spent much of the past few days talking with administrators at his school, trying to figure out what he will do if the ban persists.

Because of his sexuality, Hemmatian won't return to Iran permanently if he were to be denied reentry here. Perhaps he will finish his degree at a university in Canada or Europe. But the thought of losing his community at Brown is hard to stomach.

“I've pretty much set up my life here,” he said. “I would just have to leave it all behind.”

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