It is literally a thin wire, but it has created a wide chasm that is splitting Williamsburg's Hasidic community.

The wire, known as an eruv, is strung from poles along the perimeter of a portion of the ultra-Orthodox Jewish northern Brooklyn neighborhood.

Although it weighs practically nothing, it is heavy with symbolism: once inside its boundaries, Hasidim can, for example, carry a prayer shawl, lean on a cane or push a baby stroller on the Sabbath.

According to Judaic law that has stood for thousands of years, unless an eruv is in place, it is forbidden to carry anything outdoors on that day of rest.

But the Hasidic community in Williamsburg has become so divided over whether an eruv should be put up that doctrinal debates have erupted into fistfights. A recent series of brawls led to arrests.

Opponents of the eruv and the "walls" it creates see it as an affront to their faith and a sin. Its supporters counter that when properly sanctioned by a rabbi, the eruv makes their lives easier.

"It's a perfect thing," said a 43-year-old Hasidic mother, waiting on a local street last week to pick up her young daughter after school. "Disabled children and older people in wheelchairs can go to synagogue. Mothers with little babies, they wouldn't have to hire a baby-sitter."

But just across the street, a 32-year-old mother of five children said simply, "We're against it because our rabbi said so."

The women - like most others interviewed, they declined to give their names - aren't alone in their divided opinions about the wire.

In the week after Passover this year - around the time a communitywide eruv was erected - screaming matches erupted between men carrying, rather than wearing, fur hats on the Sabbath and those who opposed the practice. At times, the verbal confrontations escalated into violent shoving matches.

Five arrests

When fighting broke out on the streets on Saturday, April 26, police moved in and arrested five Hasidic men on disorderly conduct charges.

"We have to make sure we protect everyone's religious beliefs," said Deputy Inspector Larry Nikunen, commander of the 90th Precinct in Williamsburg. But, he added, "It's a safety issue when you're dealing with a large crowd."

Police have beefed up area patrols.

The exact location of the eruv is known only to those who put it up. They say it generally runs along Kent Ave., east on Broadway to Flushing Ave., south on Warsoff Place to Willoughby Ave. and up Taaffe Place. One 23-year-old man who lives in the neighborhood says the wire's precise location is a closely guarded secret.

"They don't give out where it is," he said. "That way no one will break it."