Why do astronomers believe in dark matter

For nine years, scientists from South Korea and France stared into space with a 2.5-meter telescope. Now they believe that they have discovered an astronomical sensation: In their opinion, contrary to what experts have thought for years, there is no dark energy in space. According to the findings of the researchers from Yonsei University in the South Korean capital Seoul and the University of Lyon, the previous calculations for dark energy are based on a systematic error.

For some years now, experts have considered dark energy to be the largest component of the entire universe. The visible matter, all stars, galaxies and gas clouds, therefore make up just under five percent of the cosmos. Another 25 percent consists of dark matter, the consistency of which is still unclear despite many speculations. And the rest, an incredible 70 percent of the universe, is said to consist of dark energy, an invisible force that ensures that space expands at increasing speed. So much for the scientific consensus.

The dark energy calculations are based on supernovae - but these may behave differently than expected

But when calculating the dark energy, for which the Nobel Prize was awarded in 2011, the experts have relied on an inadmissible premise, according to the now rebellious scientists. The calculations for dark energy, for which one has to look to the limits of visible space, are based on distance measurements using so-called 1a supernovae. The latter are stars that characteristically explode when their nuclear fuel runs out. Previously it was assumed that these explosions take place in the same way in all parts of space, which is why 1a supernovae are so-called standard candles with which one can carry out distance measurements in space.

Objects that are far away shine more reddish than objects close by, for a simple reason: They move away from the earth more quickly, which is why their light waves arrive at us "stretched", similar to the Doppler effect. Astronomers usually derive distances from this expansion, the so-called redshift, with the aforementioned 1a supernovae being used for calibration.

But experts have systematically ignored the fact that supernovae explosions have undergone an evolution since the beginning of the universe, say the renegades from South Korea and France. Younger supernovae explode differently than older ones. With this effect alone, the previous assumptions about dark energy are invalid, say the researchers. Their team leader, Young-Wook Lee from Yonsei University, is self-confident: The previous measurements of the dark energy of the universe "could be an artifact of a fragile and incorrect basic assumption," he says in a statement from his university.

Further research is needed, experts emphasize

The further away an object is from the earth, the shorter it was created after the Big Bang, as one increasingly looks into the past of the cosmos due to the long transit time of light. If 1a supernovae actually exploded billions of years ago with a different luminosity than they do today, and the researchers from South Korea and France are right, that would be a scientific revolution. It would seriously disrupt current assumptions about the composition of the universe.

Bruno Leibundgut, Senior Scientist at the European Southern Observatory ESO, does not currently see that the cosmological view of the world needs to be redrawn. He thinks further investigation is necessary. A possible source of error in the current publication could be the so-called peculiar speeds of the measured supernovae. In addition to the general speed of propagation of the universe, the characteristic stars also have their own direction of movement, which leads to a fluctuation of the redshift under equally distant objects. The measurements by researchers from South Korea and France also indicate the age of a crucial light source as 19 billion years. The ESO researcher emphasizes that this does not fit into any of the previous models. He also refers to the space satellite "Planck", whose measurements of dark energy are currently being analyzed and will probably be published this year.