Eddie Redmayne brilliant as Stephen Hawking (w/video)

The famed British physicist Stephen Hawking has never had small ideas or small ambitions, least of all his audacious youthful quest to find a “theory of everything” - one that would explain the entire universe in one simple equation.

He may not have found exactly that, but what Hawking has accomplished, we learn anew in James Marsh’s “The Theory of Everything,” featuring a superb Eddie Redmayne, is staggering. Diagnosed with motor neuron disease at 21, Hawking was given two years to live. A half century later, he remains very much alive at 72, and he and his ideas are known around the world; his “A Brief History of Time” has sold more than 10 million copies.

It’s a daunting task to capture such a remarkable life in one movie, and “The Theory of Everything” doesn’t totally escape the typical biopic trap of covering so much time that no one idea is explored deeply enough. Add to that the pressure of having a subject as well-known as Hawking.

On top of it all, there are the physical challenges of portraying his progressive disability, while also channeling the bold, complex and often impish spirit underneath. All this makes the performance of the youthful, freckled Redmayne, at 32 playing his first lead in a movie, so exciting .

We begin at Cambridge in 1963, with Stephen, a young graduate student in cosmology, exuberantly racing his bike around town, goofy and gangly, with huge black glasses and an oversized grin to match.

At a party, he spies the winsome Jane (Felicity Jones, thoughtful and touching here), and sets about pursuing her. Love blooms, and life’s possibilities appear as boundless as the universe - whether or not it has boundaries is a key question here - until Stephen starts experiencing marked clumsiness. He’s diagnosed with ALS, which will result in gradual muscular degeneration. Stephen falls into a deep depression, saved only by Jane’s stubborn love. Thus begins a marriage that will last a quarter-century, produce three children and test Jane’s physical and emotional endurance to the limits (the film is based on Jane Hawking’s second memoir, adapted by screenwriter Anthony McCarten.)

It will also survive Hawking’s near-death from pneumonia. A tracheotomy saves his life but deprives him of the ability to speak, leading to his famous computer-generated voice.

What shines through loud and clear, though, is the humanity in Hawking’s incredible story.

“However bad life may seem, where there is life, there is hope,” the physicist tells an audience. That line could seem hokey in some circumstances, but not here.