Stephen Hawking is, simply and complexly, a paragon of inspiration and tragedy. How ironic and cruel that a man with extreme intelligence is afflicted with a disease that shuts down his muscles but doesn’t affect his mind, leaving him a prisoner inside himself.

In The Theory of Everything we first meet Stephen (Eddie Redmayne) at Cambridge University in 1963, where he’s a doctoral candidate in physics. He’s racing to class on his bike with his friend Brian (Harry Lloyd) — both are youthful, vibrant, alive. Later they go to a party and Stephen meets Jane (Felicity Jones), a fellow Cambridge student studying medieval Spanish poetry. They click, but soon Stephen learns he has motor neuron disease and is given two years to live. Jane chooses to stick by him; they get married and have children.

If there’s a weak section in director James Marsh’s film it’s the opening, which is slow-moving and doesn’t develop Stephen and Jane’s love enough for us to believe she’s become so enamored that she wants to spend the rest of her life taking care of him. Any doubts we have of their love, however, are quickly allayed by her fierce commitment to his care. If you walk out of this movie questioning if you would’ve been able to do the same things Jane does, you are not alone. Presuming what we see is true, that woman is a saint. Thankfully the film has confirmable authenticity: Jane Hawking’s book Travelling to Infinity: My Life with Stephen.

Although the occasional blue hues and oversaturated lighting do the picture no favors, Marsh (an Oscar winner for the 2008 doc Man on Wire) studied archival images to ensure the costumes, production design, and stages of Stephen’s disease looked genuine. He also shot parts of the film on location in and around Cambridge, correctly believing that a school that’s been around since the 1200s isn’t going to change too much in 50 years.

One thing Marsh wasn’t sure about initially was casting Redmayne. The My Week with Marilyn (2011) and Les Miserables (2012) star had to call Marsh to ask for the role and convince the director that he could pull off the renowned astrophysicist.

And thank goodness he did. This sounds harsh but is true: The more Stephen’s disease progresses the better the movie gets, largely because of Redmayne’s Oscar-worthy performance. The distorted face, slurred speech, buckled ankles, warped fingers, and contorted mannerisms all feel devastatingly real — and should given the amount of study Redmayne reportedly did, including meeting the real Stephen and Jane. Redmayne spent so much time contorting his facial muscles that, after a few weeks, the makeup designer said the right side of his face grew more lined and muscular. This is a lived-in, physical, remarkable performance from a relative newcomer who is about to find himself on the awards circuit headed toward Oscar night. Yes, he’s that good.

As for the loving and endearing Jane, Jones plays her with sweetness and candor. We adore her because she’s a good soul, and Jones gives her the proper strength, conviction, and sadness to do what is right at all times. Even when temptations enter the picture — for her in caretaker Jonathan (Charlie Cox), for him in caretaker Elaine (Maxine Peake) — Jones’ Jane remains stoic and loving toward Stephen, bless her heart.

A good biopic is hard to pull off, especially one about a well-known, still-living public figure. There’s so much room for error, doubt, and scrutiny that the challenge could be insurmountable. And yet here we are with The Theory of Everything, a genuinely heartwarming and earnest film that’s going to be part of our cultural lexicon from now through (at least) the Oscars.