When Black Holes Leak: Einstein, Hawking, and the Universe

On March 14th, 1879, Albert Einstein was born. On March 14th, 2018, exactly 139 years later, Steven Hawking died. The calendar offers these coincidences, and we assign them meaning. In this case, there's actual substance to connect them: Einstein's theory of relativity created the framework that Hawking used to revolutionize our understanding of black holes.

The documentary from Wonder traces this intellectual inheritance across decades, from Einstein's early work on spacetime to Hawking's 1974 discovery that black holes aren't quite as black as we thought. It's a familiar story in outline—two famous physicists, their greatest hits—but the details matter because they reveal how science actually progresses. Not through lone geniuses having eureka moments, but through theories that create tools for the next generation.

The Event Horizon Problem

Black holes emerged from Einstein's equations before anyone knew what to do with them. The mathematics predicted regions of spacetime where gravity becomes so intense that nothing, not even light, can escape once it crosses a boundary called the event horizon. As one physicist in the documentary puts it: "Falling through the event horizon, it's a bit like going over Niagara Falls in a canoe. If you are above the falls, you can get away if you paddle fast enough, but once you are over the edge, you are lost."

By the 1960s, radio telescopes started picking up signals from neutron stars—extraordinarily dense objects that Einstein's theory had predicted. If neutron stars existed, maybe black holes did too. A young group of physicists, including Hawking, began working through the mathematics of what these objects would actually be like.

The assumption was straightforward: black holes consume everything, retain nothing but mass and rotation, and that's the end of the story. Information, matter, light—all permanently removed from the universe.

Then in 1974, Hawking published calculations showing something unexpected. By incorporating quantum mechanics into Einstein's framework, he demonstrated that black holes could actually emit particles. Virtual particle pairs that constantly materialize and annihilate throughout space could be separated at the event horizon, with one particle falling in and the other escaping. The black hole would gradually lose mass and eventually evaporate entirely.

"Up to 1974, everyone, including me, thought that nothing could get out of a black hole," Hawking explained. "Then I discovered that the uncertainty principle of quantum mechanics allowed particles to leak out."

The discovery was counterintuitive enough that physicists checked the calculations repeatedly. They held up. Black holes leak. Slowly, microscopically, but they leak.

The Bomb In The Equation

Einstein's theories had a less theoretical application that arrived much faster than anyone expected. E=mc² is famous enough to appear on t-shirts, but few people work through what it actually means: a small amount of matter contains an enormous amount of energy, with the conversion rate being the speed of light squared.

In the early 1920s, Arthur Eddington realized this equation explained how stars shine. Deep in their cores, hydrogen nuclei fuse into helium, and a tiny amount of mass converts to energy in the process. Our sun has been doing this for billions of years.

The same process could theoretically be induced on Earth. When Einstein fled Nazi Germany in 1933 and settled at Princeton, he was a lifelong pacifist confronting the possibility that his work would be weaponized. Worried that Germany was already developing nuclear weapons, Einstein and physicist Leo Szilard wrote to President Roosevelt urging him to start a program. Roosevelt authorized the Manhattan Project.

On July 16th, 1945, at the Trinity site in New Mexico, 0.9 grams of matter converted to energy. Three weeks later, on August 6th, 0.6 grams of matter became energy over Hiroshima, incinerating 70,000 people instantly.

As one physicist notes in the documentary: "It's always been a mixed legacy for the history of physics, right? Like we like to think of ourselves as discovering secrets of the universe, not as blowing things up."

Einstein spent the rest of his life campaigning for nuclear disarmament, but the connection was permanent. The same theories that revealed how stars work had given humanity the capacity for species-level destruction.

Machines That Use Relativity

The Large Hadron Collider, buried beneath the Swiss-French border, accelerates protons to 99.9999991% of the speed of light and smashes them together 11,000 times per second. The particles created in these collisions are similar to those that existed moments after the Big Bang, allowing physicists to study the early universe.

Time dilation makes this possible. Some particles created in the collisions have lifetimes measured in millionths of a millionth of a second. At rest, they would decay essentially at their creation point, too quickly to study. But traveling near light speed, their internal clocks run slower from our perspective. They survive long enough to travel measurable distances through the detector before decaying.

Scientist Sudan Paramesvaran explains: "Because it's traveling close to the speed of light, its clock is running a little bit slower. This means that it's actually able to travel this distance before decaying. And so the fact that it undergoes time dilation gives us an avenue of physics to explore which we otherwise wouldn't be able to do."

The LHC is Einstein's theory operationalized. Not as an abstract concept but as the foundation for a 17-mile underground ring that recreates conditions from the first moments of the universe.

Photographing Shadows

Until 2019, we had never seen a black hole. We had excellent mathematical reasons to believe they existed, observations of stars orbiting invisible massive objects, and decades of theoretical work. But no image.

Dan Marrone and colleagues set out to photograph one using the Event Horizon Telescope—not a single instrument but a network of radio telescopes scattered across the planet from Arizona to Hawaii to Chile to the South Pole. When the data from all of them is combined, it creates a telescope effectively the size of Earth.

They targeted two black holes: Sagittarius A*, the supermassive black hole at the center of our galaxy, and a larger one in galaxy M87, 50 million light years away. The challenge was photographing not the black hole itself—which emits no light—but the event horizon, the boundary where light curves into oblivion.

In April 2019, they released the first image: a ring of light around a dark center in M87. The darkest objects in the universe, when feeding, become the brightest beacons. Matter spiraling into a black hole heats to extreme temperatures, glowing intensely just before it crosses the point of no return.

What they photographed was a shadow. A hole in the visible universe where light doesn't reflect or emit but simply ends. It was exactly what Einstein's equations predicted and what Hawking spent his career studying, made visible through an instrument that required coordinating observations across multiple continents simultaneously.

Einstein worried gravitational waves would be too small to ever detect. In 1916, he calculated that moving masses should create ripples in spacetime, but he doubted we'd develop instruments sensitive enough to measure them. In 1967, MIT physicist Rainer Weiss—"Rai" to his friends—thought we could. The documentary shows him in his cluttered emeritus office, remembering when his mentor told him, "You're not as dumb as you look. That was very important. You need somebody in your life to tell you that."

Weiss designed a system using laser interferometry that could detect movements in mirrors of a few trillionths of a meter—the sort of displacement that would be caused by gravitational waves from colliding black holes. Kip Thorne, a theoretical physicist and Hawking's friend, calculated whether any cosmic events would produce detectable signals. His colleague admitted: "I heard about the idea. I did some numbers and it was obvious that Rai had gone crazy or something. I could just couldn't believe that anyone could really pull this off. And then I spent the rest of my career eating crow and trying to help him pull it off."

They pulled it off. LIGO detected gravitational waves in 2015. Weiss won the Nobel Prize.

Two physicists born and died on the same calendar date, separated by 139 years and connected by theories that predicted invisible waves in spacetime, particles leaking from regions where nothing should escape, and the power to either understand creation or end civilization. The coincidence of dates is just that—a coincidence. The connection in their work is mathematics, observation, and the patient accumulation of evidence that the universe is stranger than we assumed.

—Bob Reynolds