The hunt for dark matter is about to get a lot cooler. Scientists are developing super-cool quantum technology to hunt for the most elusive and mysterious things in the universe, currently one of science’s greatest mysteries.
Despite the fact that dark matter exceeds the amount of ordinary matter in our universe by about six times, scientists do not know what it is. This is at least in part because no human-designed experiment has ever been able to detect it.
To tackle this conundrum, scientists from several universities across the UK have come together as a team to build two of the most sensitive dark matter detectors ever envisioned. Each experiment will hunt for a different hypothetical particle that could make up dark matter. Although they have some of the same qualities, the particles also have some radically different characteristics, thus requiring different detection techniques.
The equipment used in both experiments is so sensitive that the components must be cooled to one-thousandth of a degree above absolute zero, the theoretical and unattainable temperature at which all atomic motion would cease. This cooling must occur to prevent interference, or “noise” from corrupt world measurements.
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“We are using quantum technology at ultra-low temperatures to build the most sensitive detectors to date,” team member Samuli Autti of Lancaster University said in a statement. “The goal is to observe this mysterious matter directly in the laboratory and solve one of the biggest puzzles in science.”
How dark matter has left scientists out in the cold
Dark matter poses a major problem for scientists because, despite making up about 80% to 85% of the universe, it remains effectively invisible to us. This is because dark matter does not interact with light or “everyday” matter – and, if it does, those interactions are rare or very weak. Or maybe both. We just don’t know.
However, because of these characteristics, scientists know that dark matter cannot consist of electrons, protons and neutrons – all part of the baryon family of particles that make up everyday matter in things like stars, planets, moons, bodies ours, the ice cream. and the cat next door. All the “normal” things we can see.
The only reason we think dark matter exists at all, in fact, is that this mysterious substance has mass. Thus, it interacts with gravity. Dark matter can affect the dynamics of ordinary matter and light through that interaction, allowing its presence to be inferred.
Astronomer Vera Rubin discovered the presence of dark matter, previously theorized by scientist Fritz Zwicky, because she saw some galaxies spinning so fast that if their only gravitational influence came from visible, baryonic matter, they would drift apart. What scientists really want, however, is not a conclusion, but a positive detection of dark matter particles.
One of the hypothetical particles currently put forward as a prime suspect for dark matter is the very light “action”. Scientists also theorize that dark matter may consist of new, more massive particles (as yet unknown) with interactions so weak that we have not yet observed them.
Both actions and these unknown particles would exhibit extremely weak interactions with matter, which could theoretically be detected with sufficiently sensitive equipment. But two prime suspects mean two investigations and two experiments. This is necessary because current dark matter searches typically focus on particle masses between 5 and 1,000 times the mass of a hydrogen atom. That is, if dark matter particles are lighter, they can be lost.
The Quantum Enhanced Superfluid Technologies for Dark Matter and Cosmology (QUEST-DMC) experiment is designed to detect ordinary matter colliding with dark matter particles in the form of unknown new weakly interacting particles that have masses between 1% and a few times more than one hydrogen atom. QUEST-DMC uses superfluid helium-3, a light and stable isotope of helium with a nucleus of two protons and one neutron, cooled to a macroscopic quantum state to achieve record sensitivity in detecting extremely weak interactions.
QUEST-DMC would not be able to detect extremely light particles, however, which are theorized to have masses billions of times lighter than a hydrogen atom. This also means that such shares would not be detected by their interaction with particles of ordinary matter.
However, what they lack in mass, stocks are predicted to make up for in numbers, with these hypothetical particles being suggested to be extremely abundant. That means it’s better to search for these dark matter suspects using another signature: the tiny electrical signal that results from the decay of stocks in a magnetic field.
If such a signal exists, detecting it would require stretching the detectors to the maximum level of sensitivity allowed by the rules of quantum physics. The team hopes that their Quantum Sensors for the Hidden Sector The quantum amplifier (QSHS) would be able to do just that.
If you’re in the UK, the public can view the QSHS and QUEST-DMC experiments at Lancaster University’s Summer Science Exhibition. Visitors will also be able to see how scientists infer the presence of dark matter in galaxies using a gyroscope in a box that moves strangely due to invisible angular momentum.
Additionally, the exhibit features a light-dilution refrigerator to demonstrate the ultra-low temperatures required by quantum technology, while the model dark matter particle collision detector shows how our universe would behave if dark matter were to exist. it interacted with matter and light just like everyday matter.
The team’s papers detailing the QSHS and QUEST-DMC experiments were published in The European Physical Journal C and on the arXiv papers repository.