Physicists Propose a Mirror Universe Where Time Moves in the Opposite Direction

The theory could solve certain stubborn physics questions such as, where’s all the antimatter.

Imagine waking up after death and living out your old age, until you grew young enough to have a career, and hoped someday to go to college. This is what life might be like in the “mirror” universe, the exact opposite of ours. According to two teams of physicists, our universe may have a twin where time moves backward.


Of course, this is all just theoretical. But the theory answers some fundamental questions physics has been wrestling with for quite some time. One is, if the universe during the Big Bang was made of equal parts matter and antimatter, where’s all the antimatter?

Paul Dirac first proposed antimatter in 1928. Since then, physicists have found a wide range of antiparticles. These are present during high energy collisions in other places in the universe and also within particle accelerators, such as the large hadron collider at CERN.

In a 1964 experiment, which won them the Nobel Prize 16 years later, James Cronin and Val Fitch proved that you cannot have an antimatter universe for the simple reason that the weak nuclear force violates this model. For a while that was that.

Then in 2004, two scientists at Caltech, Professor Sean Carroll and his graduate student Jennifer Chen, revived the mirror universe theory, by trying to address another fundamental physics question, why does time only move in one direction?

Experiments at the HLC at CERN have shown antimatter. But it’s eerily absent in nature. Getty Images.

Through the course of their investigation, they ended up creating a model of the Big Bang which shoots outward in two opposite directions. In our universe, everything is made up of matter, while in the mirror universe, its antimatter.

As time moves forward in one direction in one universe, it moves backward in the other. But from the mirror universe, time would appear to be moving backwards in ours, which begs the question, who is actually in the backwards universe, us or them?   

Generally speaking, when we talk about time, we consider the Second Law of Thermodynamics and in particular, entropy. This is the amount of disorder in a system which will eventually break it down, be it an engine, a computer, a star, or the human body. Entropy grows exponentially until sooner or later, it consumes the entire system. But instead of entropy, Carroll and Chen decided to focus on gravity.

Looking at just 1,000 particles and employing Newtonian physics, they were able to prove that this dual universe theory is possible. Their model even accounts for the weak nuclear force. Two teams of scientists have looked more deeply into this, since.

Physicists have long wondered why the universe only travels in one direction. NASA.

In 2014, one group published their findings in the journal Physical Review Letters. Three scientists collaborated on the project, Julian Barbour of Oxford, Tim Koslowski from the University of New Brunswick, and Flavio Mercati of the Perimeter Institute for Theoretical Physics. They studied a similar, self-contained, 1,000 particle system, based on gravity rather than thermodynamics.

This model showed gravity expanding in two directions, out from what’s been termed the “Janus point,” named after the two-headed Roman god. Here, entropy is how we experience time, as an ever forward motion, known in physics as the “arrow of time.” According to Barbour, if you take time as a natural phenomenon, rather than a pre-existing force, it flows in two different directions, which he contends popped up in their computer model, spontaneously.

As a result, those beings in the mirror cosmos would experience their lives as we do, but subtle differences could cause things to end up radically differently than they do in our epoch. So could you ever step into the mirror universe, should it exist? According to Mercati, no. The two epochs flow out forever from this central point and beings in one universe would never be aware of the other.

Even if there is a mirror universe, you’d never be able to cross the Janus point. Getty Images.

Dr. Carroll has built upon his theory since his groundbreaking announcement. Today, he’s at the California Institute of Technology. Carroll has teamed up with a colleague at MIT, Alan Guth. The model now is more refined, Carroll and Guth claim.

It doesn’t rely on gravity, for one thing. It works based on thermodynamics alone. It even operates smoothly when accounting for particles traveling through infinite space, rather than a self-contained system.

“We call it the two-headed arrow of time,” Guth told New Scientist, “Because the laws of physics are invariant, we see exactly the same thing in the other direction.” In this view, our universe and its mirror, may have been born out of a parent universe.

Their results haven’t been published, yet. One problem is that the model is only proven to work in terms of classical physics. Whether it’ll square with quantum mechanics or even general relativity, no one knows. Yet another issue is that it doesn’t incorporate a fundamental force of the universe, gravity. Researchers aren’t even sure of the exact structure their proposing.

“Instead of having two streams emanating from a river, it could be more like a fountain where you have lots of pairs of springs,” Carroll said. “Or just a whole host of springs flowing out of a fountain in different directions.” Perhaps our epoch is really a part of a much larger multiverse with each separate universe having its own mirror opposite, a fascinating prospect to consider.

To learn more about this theory, click here: 

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Image: The Pudding
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Chicagoland is Obamaland

Image: The Pudding

Chicagoland's celebrity constellation: dominated by Barack, but with plenty of room for the Belushis, Brandos and Capones of this world.

Seen from among the satellites, this map of the United States is populated by a remarkably diverse bunch of athletes, entertainers, entrepreneurs and other persons of repute (and disrepute).

The multitalented Dwayne Johnson, boxing legend Muhammad Ali and Apple co-founder Steve Jobs dominate the West Coast. Right down the middle, we find actors Chris Pratt and Jason Momoa, singer Elvis Presley and basketball player Shaquille O'Neal. The East Coast crew include wrestler John Cena, whistle-blower Edward Snowden, mass murderer Ted Bundy… and Dwayne Johnson, again.

The Rock pops up in both Hayward, CA and Southwest Ranches, FL, but he's not the only one to appear twice on the map. Wild West legend Wyatt Earp makes an appearance in both Deadwood, SD and Dodge City, KS.

How is that? This 'People's Map of the United States' replaces the names of cities with those of "their most Wikipedia'ed resident: people born in, lived in, or connected to a place."

‘Cincinnati, Birthplace of Charles Manson'

Image: The Pudding

Keys to the city, or lock 'em up and throw away the key? A city's most famous sons and daughters of a city aren't always the most favoured ones.

That definition allows people to appear in more than one locality. Dwayne Johnson was born in Hayward, has one of his houses in Southwest Ranches, and is famous enough to be the 'most Wikipedia'ed resident' for both localities.

Wyatt Earp was born in Monmouth, IL, but his reputation is closely associated with both Deadwood and Dodge City – although he's most famous for the Gunfight at the O.K. Corral, which took place in Tombstone, AZ. And yes, if you zoom in on that town in southern Arizona, there's Mr Earp again.

The data for this map was collected via the Wikipedia API (application programming interface) from the English-language Wikipedia for the period from July 2015 to May 2019.

The thousands of 'Notable People' sections in Wikipedia entries for cities and other places in the U.S. were scrubbed for the person with the most pageviews. No distinction was made between places of birth, residence or death. As the developers note, "people can 'be from' multiple places".

Pageviews are an impartial indicator of interest – it doesn't matter whether your claim to fame is horrific or honorific. As a result, this map provides a non-judgmental overview of America's obsession with celebrity.

Royals and (other) mortals

Image: The Pudding

There's also a UK version of the People Map – filled with last names like Neeson, Sheeran, Darwin and Churchill – and a few first names of monarchs.

Celebrity, it is often argued, is our age's version of the Greek pantheon, populated by dozens of major gods and thousands of minor ones, each an example of behaviours to emulate or avoid. This constellation of stars, famous and infamous, is more than a map of names. It's a window into America's soul.

But don't let that put you off. Zooming in on the map is entertaining enough: celebrities floating around in the ether are suddenly tied down to a pedestrian level, and to real geography. And it's fun to see the famous and the infamous rub shoulders, as it were.

Barack Obama owns Chicago, but the suburbs to the west of the city are dotted with a panoply of personalities, ranging from the criminal (Al Capone, Cicero) and the musical (John Prine, Maywood) to figures literary (Jonathan Franzen, Western Springs) and painterly (Ivan Albright, Warrenville), actorial (Harrison Ford, Park Ridge) and political (Eugene V. Debs, Elmhurst).

Freaks and angels

Image: Dorothy

The People Map of the U.S. was inspired by the U.S.A. Song Map, substituting song titles for place names.

It would be interesting to compare 'the most Wikipedia'ed' sons and daughters of America's cities with the ones advertised at the city limits. When you're entering Aberdeen, WA, a sign invites you to 'come as you are', in homage to its most famous son, Kurt Cobain. It's a safe bet that Indian Hill, OH will make sure you know Neil Armstrong, first man on the moon, was one of theirs. But it's highly unlikely that Cincinnati, a bit further south, will make any noise about Charles Manson, local boy done bad.

Inevitably, the map also reveals some bitterly ironic neighbours, such as Ishi, the last of the Yahi tribe, captured near Oroville, CA. He died in 1916 as "the last wild Indian in North America". The most 'pageviewed' resident of nearby Colusa, CA is Byron de la Beckwith, Jr., the white supremacist convicted for the murder of Civil Rights activist Medgar Evers.

As a sampling of America's interests, this map teaches that those aiming for fame would do better to become actors, musicians or athletes rather than politicians, entrepreneurs or scientists. But also that celebrity is not limited to the big city lights of LA or New York. Even in deepest Dakota or flattest Kansas, the footlights of fame will find you. Whether that's good or bad? The pageviews don't judge...

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