How much energy does dark matter have

astrophysics What is dark energy?

Gravitation is sometimes weaker, sometimes stronger, depending on whether a planet, a sun or a galaxy is nearby. It is probably very different with dark energy. No matter where we look, no matter in which direction of the universe, everywhere we measure the same speeds depending on the distance. And that's why scientists believe that dark energy is something completely different. Dark energy seems to be everywhere and equally strong everywhere. "Dark energy in central Germany has the same value as dark energy in the Ruhr area. It has the same value in my body, in your body. There is dark energy everywhere," says Hildebrandt

Bound objects: where the dark energy is too weak

Is there dark energy everywhere? Something doesn't seem right. Galaxies drift apart in three million light years, but my coffee machine is still in the same place every morning - how can that be explained? "That's because the earth, our solar system and even our galaxy are so-called bound objects. The dark energy is simply far too weak on these scales because there are other, much stronger forces that hold the bodies together, ours Hold together the solar system that hold our galaxy together, hold your desk or your place of residence together, "says Hildebrandt.

That means: first of all, the distances are too small here. Dark energy is so weak that it obviously needs unimaginable widths to unfold and, on the other hand, her hands are tied here. Here gravity is the queen. Here the dark energy crouches quietly, helplessly in the corner and has nothing to report. But the further we look, the weaker the gravity becomes, the more noticeable the dark energy becomes. But it only gets stronger out there. According to Hildebrandt, the theory sees this apparent increase in dark energy as follows:

In the early universe it has exactly the same value - the energy density - as in the late universe. However, the universe expands, that is, all other substances thin out over time. Ordinary matter simply thins out as the universe expands. That doesn't happen with dark energy. Since it is constant, it becomes more and more important in relative terms.

Prof. Hendrik Hildebrandt

The standard model of the universe wobbles

So there are already a few ideas about dark energy, at least what it is not, or what properties it could have.

Astrophysicists like to use mathematics to describe the universe, and in these equations dark energy, the mysterious unknown, presents itself as something with negative pressure. We do not know this property of matter on earth. Each atom moves, thus exerting a certain pressure on its surroundings and has an attractive effect due to its mass. This state of dark energy seems to be most comparable to the state of vacuum. But it is much, much weaker, so that a relationship is hardly likely.

So what is it, the dark energy? Is it just another natural constant, for example for the property of space? Scientists would be disappointed if that were the case. They hope for more, namely that behind this observation that space is expanding ever faster, perhaps new forms of matter or unknown properties of atoms are hidden. The more precisely we measure, the more shaky the so-called standard model that we have of the universe, the more puzzling the universe becomes.

New fundamental truths about the universe

We want to change that. We want to understand more of this universe. We gave it all nice names: dark energy, dark matter. But in principle it's just a job for us. Namely, to fill these names with life and to understand what these mysterious substances are all about. That is, on the basis of these cosmological observations, we could find out something new about the most fundamental laws of nature.

Hendrik Hildebrandt

So it's about more than just finding out how the universe might end, whether it will fly apart faster and faster and whether the last atom will be torn apart by dark energy in the so-called Big Rip sometime in 20 or 40 billion years - or whether this expansion will someday times stop. There is probably more to dark energy than that. It is an indication that the world may function differently than we previously thought. A new theory of the universe is in the starting blocks.