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Astronomie - Secrets of our universe live in a big blue cylinder

19.01.2019

There isn’t much on Earth but you can find it just about everywhere else — how a type of helium might tell us how everything we know got its start.

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It doesn’t look like much. It’s about two meters tall, the width of an old tree, and the shade of a blue Lego block. But inside the metal cylinder, under intense pressure at bone-chilling conditions, a special form of helium is providing clues to the oldest question: how did the universe come to be?

The universe in a droplet

Found at the very core of our planet and in the expanses of outer space, helium-3 has special properties, especially when cooled to a temperature 2 000 000 times smaller than that of any normal room. That’s when things get exciting.

To the untrained eye, the substance seems to do strange things in its super-chilled, superfluid state. If you mix it, the resulting whirlpool will spin forever. It seems to defy basic principles as it appears to drip through glass.

While it behaves strangely in Earth terms, helium-3 actually shares a lot in common with the elementary particles that formed after the Big Bang, the universe’s initial expansion. What’s more, it mirrors the structure of empty space, what scientists call the quantum vacuum.

 

Vladimir Eltsov, Senior Scientist at Aalto’s Low Temperature Laboratory, says it comes down to its intrinsic properties. ‘Let’s look at a donut: your eyes see something twisted and that has a hole. When you look at space or a superfluid in a glass, you don’t automatically see that there is some donut-like shape, but in fact that twist and hole—called topical properties—are hidden there.’

With helium-3 researchers get to investigate the ‘donuts’ up close, which in turn gives clues on how pieces of the universe emerged.

Helium-3 tells us about the foundations of our world, why the universe is built the way it is.

Grigori Volovik, Professor Emeritus

 
 

‘Helium-3 tells us about the foundations of our world, why the universe is built the way it is,’ says Grigori Volovik, Professor Emeritus at Aalto University.

A global pioneer in the study of connections between cosmology, high-energy physics and condensed matter, Grigori has spent the last four decades working with the substance, carefully unravelling some of the most abstract and confusing concepts out there. He is a proponent of its power to explain many kinds of phenomena, even questions others see as still open.

Big question, simple answer

Scientists have hotly debated the energy density of space, or cosmological constant, since it became clear that the universe is expanding at an accelerating rate. Theory placed the number at 120 orders of magnitude larger than what was being observed, a mismatch is so big and so significant that some have called it science’s biggest blunder.

‘From the point of view of Helium-3, the answer is simple—absolutely,’ Grigori says. In scientific terms, his work has shown that deviations from perfect equilibrium would induce a nonzero cosmological constant, an explanation in line with what astronomers have observed in recent years.

And when we know the basics of how the universe came to be, what comes next?

‘We want to move forward. We want to know how vacuum energy, the universe, approaches an equilibrium state,’ states Grigori. With enough time, about 2 trillion years, theory says the universe should reach a state where energy is equally distributed, a stage where no life could exist. Helium-3 may provide a way to see this happen in a miniature, Earth-bound scale.

In the meantime, researchers are gathering lessons from helium-3 to make technological advancements with the potential to touch us all. New topological materials that make use of hidden ‘twist-and-hole’ properties could be the key to reliable quantum computing or room-temperature superconductors, which have only been theorised—for now. 

Quelle: Aalto University

 
 
 
 
 
 
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