It won't be just the balloons, marching bands and floats on display in the annual Macy's Thanksgiving Day Parade. The laws of physics will also be on parade.

For the first time in its more than 80-year history, the parade route is bypassing Broadway, which cuts a diagonal slice through Manhattan, as it makes its way south from the Upper West Side to the finish at Macy's flagship store in Herald Square.

Instead, participants will use a new route _ one that traverses the grid of the city's streets and avenues, includes turns around five corners, and is slightly longer than in previous years.

The demands of the new route will challenge the marching bands and handlers of the parade's signature balloons, for whom precision is key, said Brian Schwartz, physics professor at the Graduate Center of the City University of New York.

"There really is a lot of science" to it, he said.

"If they're taking a new route, they're going to have to be really careful in the turning of the corners," he said.

The new 2.65-mile route came about because parts of Broadway have been closed to vehicular traffic, making it off limits to floats this year.

Macy's giant balloons, featuring Buzz Lightyear, Spider-Man, and Ronald McDonald this year, among others, measure several stories tall and wide and are filled with thousands of cubic feet of helium. Each balloon is tethered to several human handlers _ the number depends on the size and shape of the balloon _ who are responsible for guiding it down the route on foot.

The physics involved with moving a balloon down a straight path are different from what's needed for a corner, Schwartz said.

"If you're doing a turn, then the people on the inside of the turn have to walk slower than the people on the outside of the turn," he said. "It has to be very well-coordinated."

The handlers also have to know when to start their turning motion and how wide a turn to take, he said, likening it to trying to turn a car into a narrow parking space. If the driver turns too sharply or too widely, the car won't fit into the space properly.

Wind could also be an issue, Schwartz said, with changes in the direction of the route meaning changes in how the wind hits the balloons and what handlers have to do to compensate.

"The tension on the ropes will be changing, and people have to adjust for that in real time," he said.

The effect of the wind on the balloons is something that Macy's is mindful of, and city guidelines are in place to ground the balloons if the winds are too high.