Particle physics experiments

Can we see the dark energy of the Earth? New experiences offer hope.

Paul M. Sutter is an astrophysicist at Ohio State University, host of Ask an astronaut and “Space radio, “and author of”Your place in the universe. ”Sutter contributed this article to The expert voices of Space.com: Op-Ed & Insights.

The true nature of dark energy continues to elude our comprehension, despite two decades of investigation. Frustratingly, most attempts to explain dark energy fail extremely rigorous particle physics tests.

But new research shows how a hypothetical form of dark energy could be fabricated inside the sun and could be detected here on Earth. In fact, we may have seen it before.

A secret in the dark

In 1997, astronomers surprised themselves and the world with the discovery that the the expansion of the universe is accelerating. They gave this accelerated expansion a cool name – dark energy – because they didn’t understand what was causing this strange cosmological effect.

The simplest explanation for dark energy is that it is a “cosmological constant,” an additional number thrown into Einstein’s equation. general relativity theory. In other words, according to this view, the expansion of the universe is accelerating because … the expansion of the universe is accelerating – which is not exactly a satisfactory explanation. Physicists have tried to relate this cosmological constant to the quantum vacuum energy found throughout space-time, but their calculations estimate a force for accelerated expansion of about 120 orders of magnitude too large.

So maybe dark energy is not directly integrated into space-time itself. Perhaps there is a new force, a new field, or a new particle at work in the universe – something previously unknown to the Standard model of particle physics. This entity would explain the accelerated expansion, but theoretical models also run into problems here.

The problem is that once you introduce a new force, a new field or a new particle into the mixture of the ingredients of the cosmos, that force, that field or that particle will start to interact with all the other known forces, fields and particles. in physics. And because we don’t have any hints of any new physics in any of our high-energy (let alone low-energy) physics experiments, this doesn’t seem like a viable option.

Behind the screen

Maybe dark energy has one more trick up its sleeve. Perhaps there is an entity that is generating the accelerated expansion at large cosmological scales, and something within that entity is preventing it from interacting with known physics at small scales of the solar system.

This is a bit of a stretch, but since we have no idea what creates dark energy, it’s worth investigating. But how do we find something in our experiences that is designed to be hidden from our experiences?

Some theorists have proposed that dark energy could be caused by a new type of particle. This hypothetical particle would not be able to interact with other particles in the Standard Model (like electrons and top quarks), because it would have been produced in large quantities in the center of the sun, where the densities and temperatures are high enough. for interactions between dark energy and the Standard Model occur. The production of dark energy particles inside the sun would disrupt its thermal balance, altering its luminous flux, temperature and lifespan. And because the sun’s behavior is exactly what we’d expect from the Standard Model, it can’t produce dark energy particles in its nucleus, according to these theories.

But a recent article published on the arXiv.org preprint database offers another possibility: maybe dark energy doesn’t connect directly to Standard Model particles but connects to photons.

Deep in the sun, there is an area known as the tachocline, where the sun’s magnetic field is extremely strong. Magnetic fields are carried by photons, so tons of photons are produced in the tachocline. If dark energy somehow connects to photons, then dark energy particles could be produced as well.

Now you see it

The upshot is that there might indeed be a way for the sun to spit out dark energy particles. These dark energy particles would then pass through the rest of the solar mass, empty space, and pass through you right now.

There is another entity in the universe that could pass through you silently at this time: black matter. Dark matter is the invisible form of matter that makes up over 80% of the mass of the universe. Like this hypothetical form of dark energy, dark matter likely consists of a particle currently unknown to the Standard Model of particle physics and fluxes through the universe. And that too is completely mysterious.

Several experiments scattered across Earth are looking for elusive dark matter particles, as scientists hope to spot an extremely rare interaction. Recently one of these experiences, XENON1T, witnessed a signal he couldn’t fully explain – the first slight hint of such a detection.

And there is a chance, based on the latest research, that what the experiment detected was not dark matter, but dark energy. This is not a very strong detection, and it is far from a confirmation of the nature of dark energy. But a clue is a clue. It has been more than two decades since the original discovery of dark energy, and theory and experience have not managed to make much headway.

Scientists hope that future dark matter detection experiments, like XENONnT and PandaX-4T, will provide more data and finally give us our first glimpse of the dark universe.

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