Toggle light / dark theme

Physicist Ronald Mallett believes that a spinning laser loop can bend time, leading to time travel. He even has a prototype to test the idea.

Ronald Mallett is on a mission to develop a real-life working time machine.

But it will be hard because, according to what we know about physics now, time travel is impossible, even though it is often shown in science fiction.

Scientists have discovered how to reverse time inside a quantum system. From a teenager taking a stylish Delorean 88 miles per hour to two-hearted alien creatures flying a blue police box, our fiction has been filled with fun stories about time travel. However, it looks like time travel is now no longer a matter of science fiction but science fact.

In the physical world, time marches in one direction, but things aren’t so straight forward in the quantum realm. Researchers have discovered that it’s possible to speed up, slow down, or reverse the flow of time in a quantum system. This isn’t exactly time travel, but is instead implementing or reverting to different quantum states from different points in time.

How the Big Bang gave us time, explained by theoretical physicist Sean Carroll.

Up next, The Universe in 90 minutes: Time, free will, God, & more ► https://youtu.be/tM4sLmt1Ui8

In this Big Think interview, theoretical physicist Sean Carroll discusses the concept of time and the mysteries surrounding its properties. He notes that while we use the word “time” frequently in everyday language, the real puzzles arise when we consider the properties of time, such as the past, present, and future, and the fact that we can affect the future but not the past.

Carroll also discusses the concept of entropy, which is a measure of how disorganized or random a system is, and the second law of thermodynamics, which states that there is a natural tendency for things in the universe to go from a state of low entropy to high entropy. He explains that the arrow of time, or the perceived difference between the past and the future, arises due to the influence of the Big Bang and the fact that the universe began in a state of low entropy.

The trouble starts when they attempt to beam up from a planet during an ion storm. Something goes wrong. They appear aboard the Enterprise, but things are askew: Crew members greet the captain with Nazi-style salutes, and First Officer Spock sports a goatee. Observing these small but significant differences, Kirk muses that the crew has materialized in “a parallel universe coexisting with ours on another dimensional plane.”

These days, one parallel universe is hardly enough for science fiction. Instead, it seems the entire multiverse is having its Hollywood moment. Films like Doctor Strange in the Multiverse of Madness and Everything Everywhere All at Once entice the viewer with multiple versions of various characters and a dizzying array of alternate realities. Though they’re not particularly heavy on the physics, these films are definitely latching onto something. The idea of the multiverse — the provocative notion that our universe is just one of many— has fully cemented itself in mainstream pop culture. (Or, at least, in the current phase of the Marvel Cinematic Universe.) Its appeal as a storytelling device is obvious. Just as time travel allowed Marty McFly to experience different timelines in the Back to the Future series, multiverse tales allow characters to explore a multitude of worlds with varying degrees of similarity to our own, as well as altered versions of themselves.

While Hollywood can’t seem to get enough of the multiverse, it remains deeply controversial among scientists. Ask a prominent physicist whether they believe in a multitude of universes beyond our own, and you’ll get either a resounding yes or a vehement no, depending on whom you encounter. Advocates on the two sides show no mercy toward each other in their books, on their blogs, and, of course, on Twitter. But physicists didn’t pull the idea out of thin air — rather, several distinct lines of reasoning seem to point to the multiverse’s existence, bolstering the idea’s merit. Sabine Hossenfelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies, has called the multiverse “the most controversial idea in physics.”

From creator Brad Wright, who honed his expertise writing on three Stargate shows for 14 years, Travelers is a departure from traditional sci-fi tropes. It’s the kind of modern, grounded sci-fi that funnels its wriggling ball of time travel strands through the lenses of empathetic, endearing characters.

This team of time-traveling agents, called “travelers,” inhabit the bodies of people who are close to death. With the help of GPS coordinates, historical records and social media, the consciousnesses of the future travelers are inserted into the bodies of 21st century civilians. It’s the cleanest way for the travelers to go back in time and complete their mission, utilizing the lives of those who were going to die anyway.