Could Light Reveal Mirror-Image Life Before Anyone Builds It?

Scientists in the United Kingdom say they have worked out what they believe is the first way to detect “mirror life,” a hypothetical form of life built from reversed versions of the molecules found in living things on Earth. According to ScienceDaily, which published the University of Strathclyde's summary of the work, the idea is to use special glowing molecules and a kind of polarized light, the same family of technology behind 3D movie glasses.

Mirror life does not exist. The researchers stress that their method is a precaution, not a response to any present threat, and so far it is a proposal rather than a tested tool.

What exactly is mirror life?

Many molecules come in two forms that are mirror images of each other, much like a left hand and a right hand. Both versions contain the same atoms linked in the same order, but their three-dimensional shapes differ. This property is called chirality, or molecular “handedness.”

Mirror life would be an artificial organism assembled from the opposite-handed building blocks. Nothing like it has been created.

Why do some experts worry about it?

Small differences in shape can matter a great deal in biology. The report notes that the human body can respond very differently to the two mirror versions of the same molecule, so that one form of a drug might treat a disease while its mirror twin does nothing or causes harm.

Some experts fear that an organism built from reversed molecules could behave unpredictably around natural life and might slip past some of the defenses that protect people, animals and plants. The chance of it appearing is considered low, but the possible consequences are seen as serious enough to prepare in advance.

The concern has led scientists to recommend limits on research aimed at producing organisms that reproduce using mirror-image molecules. It has also drawn attention from the UK Government Office for Science and the United Nations Secretary General's Scientific Advisory Board, according to the report.

How would the detection method work?

The approach relies on a phenomenon called circularly polarized luminescence, or CPL. Light can be polarized in patterns that rotate in opposite directions, and reading those patterns reveals the three-dimensional arrangement, and therefore the handedness, of certain molecules and biological structures.

The team suggests using fluorescent probes that attach to particular structures inside cells. Once attached, the probes would give off characteristic CPL signals. Analyzing them could show whether a sample carries the handedness of ordinary life or the reverse. The researchers describe the signals as a kind of molecular fingerprint.

A single probe could give misleading readings, so the team proposes combining several probes that recognize different cellular structures. Looking at multiple signals together is meant to make the results more dependable and cut the risk of false readings.

Who did the research?

The work was led by Dr. Lewis MacKenzie of the University of Strathclyde and carried out with Professor Robert Pal of Durham University. It was published in the journal Royal Society Open Science.

MacKenzie said mirror life is not expected to appear tomorrow, but that developing detection methods before they are needed makes sense. He added that he and Pal had been working on CPL technologies before the recent concerns became prominent, and that guarding against mirror life was a natural fit for their research.

Why it matters

For most readers, nothing changes today. There is no mirror organism to worry about, and the method has not been shown to work on one. What the proposal offers is groundwork: a way for scientists to be ready if such an organism were ever made, whether on purpose or by accident.

One practical advantage, the researchers say, is that the technique could be studied and refined using ordinary biological samples. That means nobody would have to build a mirror organism just to test whether the detection idea works. The team also believes the method could eventually be built into several kinds of scientific equipment, which could allow screening for mirror life in different settings.

As with any single study, the finding should be treated as an early step. The detection approach is proposed, not proven, and the broader debate over how to handle research on mirror-image organisms continues among scientists and government advisers.

Around Prague, based on reporting by ScienceDaily