The science refresher you need before diving into Netflix's hit sci-fi series '3 Body Problem'

  • Netflix's "3 Body Problem" is based on a science-fiction trilogy and follows a group of physicists.

  • We asked an astronomer and an aerospace engineer to explain some of the show's scientific concepts.

  • It might help to have a bit of background on the Fermi paradox and the Wow! signal before you watch.

The upcoming Netflix show "3 Body Problem" is a sci-fi story about a group of physicists grappling with the discovery of an alien civilization.

Taking its name from a tricky bit of orbital mechanics — three celestial bodies moving around each other — the show is based on the science-fiction trilogy "Remembrance of Earth's Past" by Liu Cixin.

In the show, several of the main characters studied physics at Oxford University. Luckily, you don't need to have the same background to enjoy the show.

However, there are a few scientific concepts that might be helpful to know before you tune in on March 21.

The three-body problem is unsolvable and chaotic

Some of the show's action takes place in a virtual world that's orbited by three suns. The celestial mechanics of such a planet have long perplexed scientists in the real world.

"This is a centuries-old problem," Shane Ross, an aerospace and ocean engineering professor at Virginia Tech, told Business Insider.

Isaac Newton was able to figure out the two-body problem, how a pair of massive objects like stars or planets move when affected by each other's gravity.

"The two-body problem is sort of the paradigm of stability," Ross said. Adding in a third body, though, makes everything topsy-turvy.

isaac newton
Isaac Newton.Georgios Kollidas/Shutterstock

From a mathematical perspective, "it's unsolvable," Ross said of the three-body problem. "You can't write out the solution for all time as some algebraic formula."

It's a bit like the butterfly effect: a small change can vastly alter the outcome. "Any uncertainty we have in the initial conditions grows exponentially, to the point where the future state of the system is essentially unpredictable."

Alpha Centauri is the closest star system to Earth

The three-body system in the story is based on a real neighboring star system called Alpha Centauri.

At about 4 light-years from Earth, it's the closest star system to our own and contains three stars: Alpha Centauri A, Alpha Centauri B, and Proxima Centauri, which has two planets orbiting around it.

"We're talking about something super close to us," Franck Marchis, a senior planetary astronomer with the SETI Institute, said. "It's like looking at the backyard of neighbors, basically."

Alpha Centauri.
A view of the bright triple-star system Alpha Centauri.ESO/Digitized Sky Survey 2 Acknowledgement: Davide De Martin

However, it would take special conditions for life, at least as we know it, to survive, on either planet around Proxima Centauri. "The conditions for life are extremely rare," Ross said. "I think the Earth is a very special planet," adding that "there could be life that takes some other form that we don't know about."

If a civilization from Alpha Centauri evolved at a similar pace to our own, then "they're probably more advanced than us," Marchis said because the system is estimated to be between 5 and 7 billion years old whereas Earth's solar system formed 4.5 billion years ago.

The Fermi paradox poses the question, where are all the aliens?

If there are highly evolved beings on other planets, why haven't they gotten in touch? That's the question astrophysicist Ye Wenjie is asking when she brings up the Fermi paradox in the show.

In 1950, Nobel prize-winning physicist Enrico Fermi wondered where all the extraterrestrials were. Decades later, other scientists picked up the question. If other civilizations existed, they must have left some evidence.

Enrico Fermi at a lab at Columbia University
1954: Italian atomic physicist and Nobel Prize winner Professor Enrico Fermi (1901 - 1954), inspecting equipment at the laboratory of Columbia University, USA, where he will teach.Keystone/Getty Images

To Marchis, what became known as the Fermi paradox is an outdated way of thinking. "The idea is that because we are a civilization that's become technologically advanced, the first thing that we do is to travel through the galaxy, 'Star Trek'-like," he said.

Instead, he prefers the "zoo hypothesis."

If they are truly advanced, he said, "they probably reached a certain level of sentientness or consciousness that makes them more respectful of other civilizations which are progressing."

In short, they're purposefully avoiding contact with our planet.

Aliens could have communicated through the Wow! signal

One of the most mysterious potential alien communications is known as the Wow! signal. In the show, Clarence (Benedict Wong) describes how the strange signal was picked up in Ohio and China.

During the 1970s, researchers at Ohio State University really were involved in the Search for Extraterrestrial Intelligence, or SETI. They used a radio observatory nicknamed "Big Ear" to try and pick up extraterrestrial communications.

In 1977, volunteer Jerry Ehman was looking at a computer printout of a signal Big Ear had picked up three days earlier. He circled the numbers and wrote "Wow!" alongside them. The 72-second signal was strong and located at a frequency known as the hydrogen line.

Wow! signal alien
The famous—or infamous—”Wow!” signal detected in 1977.Big Ear Radio Observatory and North American AstroPhysical Observatory

At the time, researchers thought aliens would communicate via that frequency "because it's the easiest way to send signals through the galaxy," Marchis said.

The signal has never repeated or been detected again Marchis said. (And no other observatories reported picking up the signal, in China or anywhere else.)

Since the signal itself wasn't saved, there's no way of knowing if it contained a message, Marchis said. Some more mundane explanations for the signal have been suggested, like the radio transmission reflecting off a passing comet.

SETI has come a long way since the '70s, with many researchers using newer technology and a broader range of signals, Marchis said. "We assume that if aliens will communicate with us," he said, "they're slightly more advanced than the people from the 1970s."

Occam's razor suggests simple explanations are often better

Like many other sci-fi movies and shows before it, including "Contact" and "Fringe," "3 Body Problem" makes a reference to Occam's razor.

In 1852, philosopher Sir William Hamilton coined the term "Occam's razor," attributing the idea to 14th-century theologian William of Ockham.

William of Ockham had written, "Numquam ponenda est pluralitas sine necessitate," or "Plurality must never be posited without necessity." It's an idea that Aristotle and Ptolemy also stated.

Today, the well-known concept is usually stated as "the simplest solution is usually correct." The often-cited example is, if you hear the sound of hoofbeats, think horses, not zebras (provided you're not on the savanna).

Particle accelerators move particles at almost the speed of light

The bizarre, illogical behavior of subatomic particles inside particle accelerator experiments spurs a major plot point in the show.

Often located in large facilities, particle accelerators like the Large Hadron Collider have been used in lots of different ways, from medical research to industrial applications like sealing chip bags.

physics female scientist particle accelerator
Scientists use particle accelerators in a variety of ways, for experiments and industrial and medical applications.Monty Rakusen/Getty Images

Many of these devices use magnets and magnetic fields to speed up and collide charged particles, which then release energy. Particles move at almost the speed of light. In this unique environment, scientists can try to solve some of the biggest questions in physics.

For example, in 2012, the LHC helped researchers observe the Higgs boson, the "God particle" that helps explain why our universe has mass.

Neutrino detectors are built deep underground

The trailer for the show includes a dramatic shot of one of the characters stepping into what looks like a neutrino detector and falling, presumably to her death.

Neutrinos, also known as ghost particles, are subatomic particles that the sun and supernovae create. Billions pass through your body at any given time.

A person in a hard hat stands in a gold room that's the protoDUNE experiment
A prototype detector, part of the protoDUNE experiment, at CERN.Maximilien Brice/CERN

Much like particle accelerators, the devices may help unlock some of the universe's secrets. They're often built underground to shield them from cosmic rays that can interfere with the data.

Three celestial bodies lined up is known as syzygy

During the show's third episode, the three suns in the virtual world all line up in a triple eclipse.

Ross pointed out that the show debuts around a "cosmically significant day," the vernal equinox. "That's the day when all across the world it's equal daylight and nighttime," he said.

Total solar eclipse
The 2017 total solar eclipse at 100% totality.John Finney photography / Getty Images

It's also close to the upcoming solar eclipse that has a path of totality through a large portion of North America.

"That's the sun, moon, and Earth all in a line," Ross said. "It's called syzygy, when three celestial bodies are exactly in a line."

Protons are subatomic particles

Protons exist inside an atomic nucleus.YouTube/MonkeySee

In one of the show's more science-fiction moments, tiny supercomputers called sophons cause all sorts of unusual activity.

A sophon is completely fiction. However, it's described as a proton that the aliens have transformed into a sentient supercomputer. And protons, at least, are real.

In real life, protons are positively charged particles found in atomic nuclei, usually alongside neutrons.

The periodic table is arranged by increasing atomic number, which is equal to the number of protons in an element's nucleus.

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