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Sciencing the “bazinga!” out of The Big Bang Theory

Behind the scenes: what it’s like to fact-check Sheldon Cooper

All photos courtesy of Warner Bros. Television Entertainment/Greg Gayne

David Saltzberg is science consultant behind The Big Bang Theory and Young Sheldon. He’s the one who keeps the facts tight. We asked him what’s really on the whiteboards – and he gave us an Easter Egg

The best organism for human beings to merge with is the lichen itself. That way, you’d be human, fungus and algae. Triple threat. Like three-bean salad.

‘Sheldon Cooper’, The Big Bang Theory

You can’t hear explosions in space. Or can you? When the Death Star exploded, should George Lucas have held the boom and lit a silent firework display? Should stormtroopers have quietly disintegrated? And should the Millenium Falcon have kept the racket down and glided through space without a sound?

Professor David Saltzberg, science adviser on The Big Bang Theory and Young Sheldon, isn’t convinced about the common myth that there is no sound in space, and wants us to give filmmakers a break.

“People have tried to create space flights without sound, and they’re rather dull,” he says, so he understands why noisy space scenes are the directorial go-to.

“Space is a vacuum, but it’s not a complete vacuum,” he says. “There are small amounts of particles. You can imagine there are some very, very faint sound waves travelling through because something exploded, and then someone has a microphone and they’re picking it up and amplifying it.”

Then there’s the laser beam issue. “You typically don’t see laser beams,” David says. “But it’s just not very interesting to not see them.”

This kind of quandary is now David’s world. But being a TV science consultant was never in his career plan. He’s a professor and the physics and astronomy chair at UCLA (University of California), and has spent years working at CERN (the European Organization for Nuclear Research) – what he calls a Mecca for particle physicists. Becoming the brain behind The Big Bang Theory was a big, happy accident.

“I was just working as a physicist. Living here in Los Angeles, you meet a lot of people who are in show business,” he says. “And then through a friend of a friend of a friend situation, the producers were making this show and just wanted to have someone look at the first script.”

The set decorator wanted to see some student apartments too, so the crew took a trip to see where some of David’s graduate students lived. 

This trip was a big source of inspiration for the original, unaired pilot back in 2006 – a prototype. The colours were darker; the apartment was dingier. It was set in New Jersey instead of Pasadena.

“One of the things they decided to change from one pilot to the next was to make it brighter, more colourful, a happier environment. And so I tell my grad students that their real lives were too depressing,” David says.

Since that trip, David has taken part in every taping of The Big Bang Theory.

“How this turned into a permanent 12-year relationship – that’s lost history,” he says.

The science / art equation

Every week during production, David went to The Big Bang Theory tapings and chatted to the writers, who already had a lot of science knowledge between them.

“They were thinking of a future show, or I would bring a guest who was a scientist, and they would talk to that person. I would warn my guests that the writers were going to steal their soul,” David says.

Often, visits from these scientists would inspire new storylines. It became a launching point for the creative process.

“The stories were really human stories with the specifics of science,” David says, explaining how he wasn’t often needed in the early stages of scriptwriting. There would be universal stories (like, how do I impress my girlfriend?), but David’s job was to find a piece of science that made the story work.

In one famous episode, the characters sit on the apartment roof and bounce laser beams off the moon (and yes, we see the laser beam). But until David Saltzberg got involved in the script, there was no moon laser bouncing. The writers knew the characters were on the roof, that it was nighttime, and that they were doing something. It was up to David to fill in the gap.

“I just heard a talk about people bouncing lasers off the moon – that sounds kind of fun,” David told the team, and the idea grew from there.

“Typically, I would give them three or four ideas and they would take the one they liked,” David says. But in general, they preferred simple stories. It was only a 22-minute show, and there needed to be room for jokes.

Beyond the script, David kept the science tight for the set decorators. The whiteboards in Leonard’s apartment or Sheldon’s office are anything but random – they reflect something in the script, or something topical or contemporary. Other times they’d be full of science that wasn’t in the story, but which the characters could credibly have been discussing. When the great physicist John Wheeler died, David put some of his work on whiteboards on the set. (The visionary helped invent the theory of nuclear fission, gave black holes their name and argued about the nature of reality with Albert Einstein and Niels Bohr. As you do.)

“It was plausible, because they would have been talking about him,” David says.

David Saltzberg The Big Bang Theory
The whiteboards are anything but random

All the departments worked so well together and cared so much, that the world they created just worked.

“I’ll give you a little secret,” David begins. “They would ask me whether something should be brass bolts or aluminium bolts, for example. And the real answer is – it just doesn’t matter. But that’s not the answer they want.”

David was there, he says, to help them make the science real. They wanted to get it right.

The ‘90s science solution

The Big Bang Theory wrapped up in 2019, but David is still busy fine-tuning the science in another sector of the Big Bang universe. Young Sheldon, a prequel to The Big Bang Theory, does what it says on the tin. It follows the life of a young Sheldon Cooper and his family in Texas.

Working on this show, David says, is completely different from The Big Bang Theory, not least because of the production and its young cast.

The Big Bang Theory was filmed in front of a live audience, in chronological order, and with an air of going to see a show. The theatre was filled with multiple cameras to help it run smoothly, and the TV audience only ever sees three sides of a room – the missing wall is where the audience sits. When you hear laughter, it’s real. If Nigel in seat D15 has a honking laugh, it’ll be on the tape.

There’s no laugh track on Young Sheldon, no live audience, and no theatrical spectacle. Everything is filmed out of sequence with a single camera, across a longer period of time. It’s a different mood. 

“People might think Hollywood is exciting, but to go see a single camera comedy being made is really just like counting grains of rice. It’s really slow,” David says.

David goes to one production meeting, and that’s it. But it doesn’t mean there aren’t interesting challenges.

“Because it takes place in the early 1990s, I have to choose science from that time that makes sense,” David says. 

He works with the propmaster to find books that existed at the time. If a professor abandons their office, he rummages through their shelves to find old textbooks and magazines that can be used on the show. He’s borrowed books from the library to use as props.

“Some of my personal books now say Medford High School Library on them,” David says, thinking about how one day someone might look through his own book collection and see the stamp from the fictional library.

The public science critics were different too. After new Big Bang episodes, Twitter would often light up with analysis, dissecting what the show got right and wrong. But for whatever reason, David says, the same isn’t usually true of Young Sheldon.

In one episode, Sheldon says, “Did you know that if gravity were slightly more powerful, the universe would collapse into a ball?”

This, David says, is an accurate statement. We have a best guess for the fate of the universe, but we don’t yet know all the laws of physics.

“We’ve known the universe was expanding for a long time, but it was unclear if that expansion would be slowing,” he says. “If you think about all the matter in the universe, eventually it’s going to pull on itself, you would think, and maybe bring it all back together.”

“On the other hand, since I’ve been a professional scientist in that period, we’ve discovered that expansion’s actually accelerated. So the best guess now is that the universe will continue to expand forever.”

The Nobel Prize conundrum

When it comes to The Big Bang Theory challenges, winning a fictional Nobel Prize for Sheldon and Amy might top David’s list.

“If I could come up with a topic that’s going to win a Nobel Prize, I would probably just do it,” David says. When he asked theoretical friends, they weren’t willing to divulge ideas either.

The solution was super asymmetry. The characters never presented the theory itself, never chalked up fully-fledged equations on the blackboard, and left the audience to fill in the blanks.

“There’s this theory that’s been around since I was a graduate student called supersymmetry. It’s been a big buzzword in physics for decades. And somehow the word came to me after thinking about this for weeks or months – super asymmetry, which is kind of nonsense in many ways,” David says.

He thought somebody would have used the term already, but when he checked, he found over 20,000 papers on supersymmetry, and not a single one on super asymmetry. Which is exactly what Leonard did in the show.

“It isn’t a real theory that’s going to win a Nobel Prize anytime soon. But it’s plausible,” David says.

This plausibility was key. Making the science accurate was ultimately a creative choice for both shows, David says.

“You can imagine, if on Back to the Future they had a science consultant say, ‘Well, you can do this movie, but you can’t go back in time, because that’s not scientific,’ that would be a bit of a constraint on the movie,” he says.

For David, making things feel real, including the science, helps immerse the audience into the world of the story.

And life has imitated art. In what could be a scene from the show, David Saltzberg is now an asteroid. As are some of the other writers and actors from the show.

“There’s an astronomer named Bobby Bus and he discovered these asteroids. He’s allowed to name a certain number of them per year, and what a wonderful, pleasant surprise, he named them after us,” David says.

A friend with an infrared telescope in space found the asteroid 8628 Davidsaltzberg in his data, so now David has a picture of a little red dot hanging on his office door.

“I just hope it doesn’t come and hit the Earth and destroy life as we know it.”


Easter Egg icon

In the final episode of The Big Bang Theory, as Leonard and Sheldon finish a long job of fixing a DNA model in the apartment, Leonard says, “It may be the glue talking, but that was a very pleasurable 139 and a half hours.” If you add up the running time of the 279 episodes at around half an hour each, you’ll get the inside joke.


What’s so good about this?

For those of us that aren’t astrophysicists or microbiologists, media might be the best way to infuse our brains with some scientific content. The work of science consultants like David Saltzberg is likely to come into our lives at some point, and it just might spark an interest in the wider universe. That’s a pretty good side-dish to your comedy main course.

Katie Dancey-Downs writer profile

Meet the writer

When she’s not pretending to be a beaver holding back the rivers, Katie Dancey-Downs is a freelance writer and journalist with a passion for human stories, nature and culture. She’s travelled the world to report on issues such as vegan activism in Toronto, regenerative farming in India, and the destruction of Sacred Natural Sites in Kenya. She can usually be found with her head in a book, stomping through the forest, or wishing she looked cool on a surfboard. Follow @Katie_Dancey.

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