Through the mirror world, scientists want to detect parallel universes & exotic matter

Scientists are setting up relatively cheap experiments that just might give concrete evidence for a strange notion known as the mirror world.

Representational Image | Wikimedia Commons

There’s been a recent pattern in science in which the most astonishing ideas stand the farthest out of reach of empirical tests. We hear of parallel universes and exotic matter that may or may not be real, and can’t be detected in any case. And so it was refreshing to see small groups of scientists setting up relatively cheap experiments that just might give concrete evidence for a strange notion known as the mirror world.
The mirror world, as postulated, would exist not in some inaccessible dimension or faraway exurb of space, but right here. It would mingle with our universe, but would consist of a kind of matter that ghosts through our matter, unseen and unfelt. The mirror particles might form a relatively boring, uniform haze, or something more exciting, with mirror-image versions of all our known particles assembling themselves into mirror molecules, stars and planets.

Looking for the stuff is the remotest of long shots. The physicists embarking on the search say they expect to disprove mirror matter exists rather than prove it. That’s the right approach. Though in other fields, disproving something that doesn’t exist is considered a “failure,” in physics it’s understood that finding the truth is a success, even if the truth isn’t what you want it to be.

So why bother if it’s more likely not to exist? Such long shots are the only way to uncover more of our reality. We know we can’t live in a universe of what-you-see-is-what-you-get. There are too many anomalies. Things don’t add up. Something funny is going on.

To start with, experiments done in the 1950s show that sub-atomic particles do not behave exactly the same way when their orientations are flipped into their mirror images. Theoretically they should, obeying what’s called mirror or “parity” symmetry. One explanation for the experimental results is that mirror symmetry only appears to break down, because we’re seeing only part of a bigger picture. The symmetry might be completed by mirror image particles that have been invisible to us.

And from astronomy we have strong hints that invisible matter is out there. In the mid- and late 20th century, astronomers discovered that stars and even whole galaxies are moving around as if under the influence of the gravitational pull of huge amounts of invisible matter. They dubbed it “dark” matter, mapped out its approximate distribution and estimated its total weight as five times that of visible matter. But they have not been able to figure out what it’s made of.

If it is some kind of invisible form of matter, it isn’t just out there, but is all around us. People have proposed and searched for various so-called dark matter candidates. Mirror matter is one such candidate, though so far it hasn’t gotten that many votes; as candidates go, it’s more of a Marianne Williamson than a Joe Biden. Soon, that could change.

There’s also a closer-to-home observation that hints of the possibility of mirror matter. That comes from a discrepancy in the behavior of subatomic particles called neutrons. Neutrons, when isolated from atoms, are unstable, and over time decay into other particles, but it’s been hard to measure their lifetimes.

Experiments that trap neutrons in a magnetic field – a “bottle,” as the physicists call it – measure a shorter lifetime than do experiments that measure the lifetime of neutrons in a beam created from a nuclear reactor.

Something is up. One possibility is that neutrons are capable of transforming themselves back and forth from their normal form to an invisible mirror form, and that the magnetic field in the bottle increases the probability of such transformations. That prospect, while it sounds a little wild, is testable.

At Oak Ridge National Laboratory in Tennessee, physicist Leah Broussard and her colleagues have built an experiment that uses a 50-foot tunnel and a thick wall that ordinary neutrons couldn’t possibly breach, but mirror ones (if they exist) could ghost through.

Meanwhile, a team at the Paul Scherrer Institute in Switzerland is planning a different kind of experiment – further probing the way neutrons decay in magnetic bottles – changing the magnetic field to see whether that alters the decay rate. That complementary approach could help the Oak Ridge group figure out what to look for.

Quoted in a recent piece in New Scientist, physicist Zurab Berezhiani at the University of L’Aquila in Italy expounded on the possibility that if there are mirror neutrons, there might also be invisible mirror protons and electrons making up mirror atoms, molecules, planets and even people, all co-existing with us.

Broussard said she’s not so sure this would follow from finding mirror neutrons. She prefers not to get too far ahead of the evidence. But finding any sign of mirror matter would be an astonishing thing in any case, and might stimulate searches for wonders not yet imagined.