Why Is the Anti Gravity Path Necessary?

Q. Why is the antigravity path necessary? To keep the hunters from getting lost.

What is the purpose of the anti-gravity path in a sound of thunder?

One direct way of keeping a low profile is the use of an antigravity path (simply called "the Path", the capital denoting its importance) which allows the hunters to walk through the ancient environment without directly stepping on anything.

What does the path symbolize in a sound of thunder?

The path is the symbol for the written destiny. Since the crew insist that Eckels doesn't step off, the path that doesn't alter the already occurred future, then that path would be the route that would take them back to their normal lives.