Does matter really exist?

The unsolved mystery of existence : Of nothingness and the origin of everything

For the philosopher Martin Heidegger it was the most radical of all questions: “Why is there actually being and not rather nothing?” The answer of the natural scientist is: “Because there was the big bang.” But strictly speaking, the “big bang theory” does not explain that Origin of the cosmos itself. Rather, it describes its development after the Big Bang.

But why this story could even begin, why a “universe” emerged from a “nothing” in a big bang bang - astronomers are still puzzling over this birth secret of the cosmos.

How can "something" arise from "nothing"?

And the next riddle follows immediately: Why could the history of the cosmos go on at all after its mysterious beginning? Because whatever happened back then, an emergence from “nothing” could only have set a material zero-sum game in motion according to the conservation laws of nature: with every elementary particle its anti-particle had to have formed at the same time - an anti for every proton -Proton, for every electron an anti-electron, etc.

The particles of matter and anti-matter essentially only differ from one another in that their electrical charges are polarized in opposite directions. However, if a particle and its anti-particle meet, they annihilate each other and annihilate. Not only is the layman astonished, the astronomer is also amazed: If the cosmos had actually buzzed as many particles as anti-particles through the cosmos after its birth, his story would have come to an end quickly.

Matter and antimatter would have annihilated each other again. What would have remained is a boring universe full of radiation, but without any matter. Undoubtedly, however, there are stars and planets and living beings of flesh and blood today. But couldn't part of this matter actually be anti-matter? Perhaps anti-stars also shine in the cosmos, around which anti-planets revolve, on which anti-extraterrestrials may even live?

It only exists because the cosmos initially violated symmetries

Good stuff for science fiction stories - but so far there is no evidence that there is any significant amount of anti-matter anywhere in space. So why is there apparently only matter left in the universe while the anti-matter, which was initially present in equal quantities, has been extinguished?

The Soviet nuclear physicist, human rights activist and Nobel Peace Prize laureate Andrei Sakharov was the first to provide a possible answer in 1967: The quantum world of elementary particles is perhaps not completely symmetrical after all. For example, some particles and their anti-particles could, contrary to all expectations, obey different laws if you look at their behavior in a mirror.

Such symmetry violations would have quickly ended the original equality of matter and anti-matter in the young universe. In the particle chaos of disintegrating, mutually transforming and newly forming particles and anti-particles, the bottom line would have been a little more particles of the “baryon” variety than particles of the “anti-baryon” variety.

But that would have sealed the fate of the numerically inferior anti-baryons: All anti-baryons and the corresponding subset of baryons would have mutually destroyed each other and converted into radiation. This radiation should still flood the cosmos today.

And indeed: in 1964 such radiation was discovered by chance by the two American physicists Arno Penzias and Robert Wilson. As “cosmic background radiation”, it still fills every cubic centimeter of the huge universe with around 400 photons. This abundance of photons gives an idea of ​​the extent to which all anti-matter and almost all matter except for its small excess must have been extinguished shortly after their formation.

Mesons hold the secret to the origin of the universe

The symmetry violations of the particle processes during the first fractions of a second of the cosmos had apparently only led to a tiny majority of baryons; among billions of baryons and anti-baryons that annihilated each other, only very few surplus baryons could escape annihilation. But this small remnant became the building material for the further development of the cosmos, for stars, planets, living beings.

So do we owe our material existence to symmetry violations in the strange quantum world of elementary particles during the very first moments of the cosmos? Already possible: the quantum physicists have actually already been able to track down some particles whose anti-particles do not behave like exact mirror images. The most famous of such symmetry breakers are the mesons.

Mesons are subatomic particles that can be generated in particle accelerators and quickly decay again. As early as 1964, the US physicists James Cronin and Val Fitch discovered an unexpected irregularity in the decay of K mesons. According to the theory, certain K mesons should decay into three lighter particles, pions. But in experiments at the National Laboratory in Brookhaven, some of these K mesons only disintegrated into two pions.

This surprising decay result, however, indicated exactly one of those symmetry violations in which, according to Andrei Sakharov, more matter could arise than anti-matter. In the meantime, the elementary particle physicists have found similar symmetry violations in the decays of B mesons and D mesons. Nevertheless, the symmetry breaks found up to now are far from sufficient to explain the excess of matter that escaped its extinction by anti-matter. The amounts of matter that are found in space today, condensed in stars and planets and loosely distributed in clouds of gas and dust, are far too large for that.

In addition to this unsolved riddle of the victory of matter over anti-matter, physicists are faced with another matter riddle. It's called "Dark Matter". The name corresponds to the current state of knowledge: Nobody has seen dark matter directly until now. It only reveals itself through its force of attraction, its gravitation. In order to be able to explain all the movements observed in the cosmos - for example the movements of stars in galaxies -, in addition to "normal" matter, five times more dark matter has to drift through the cosmos and develop its gravitation.

At CERN, particles are locked in traps for years

And this is where the experimental physicist Stefan Ulmer comes into play. Perhaps - so his surprising idea - the mystery of the vanished anti-matter has something to do with dark matter. Ulmer heads the “BASE” project, the baryon-antibaryon symmetry experiment at CERN near Geneva, the world's largest research institution for particle physics. His research group includes scientists from the Helmholtz Institute at the University of Mainz.

The objects of their curiosity are the atomic nuclei of hydrogen and their anti-particles; in technical terms they are called "protons" and "anti-protons". Since it is in our world - fortunately! - apparently there are no more anti-protons, they have to be generated artificially. In the “anti-matter factory” at CERN, this has become almost everyday business these days. Once the anti-protons have been generated there with the help of a particle accelerator, they then have to be slowed down again to around a tenth of the speed of light. This happens in the magnetic and electric fields of a particle decelerator.

Then they can be directed to the individual experiments. For example in the “Penning traps” of the BASE project, named after the Dutch physicist Frans Penning, who described the principle of the traps as early as 1936: They use a clever combination of electric and magnetic fields to prevent charged particles from escaping.

Stefan Ulmer and his research colleagues lock anti-protons in Penning traps and measure their properties. For years if need be. A world record. Time enough to “take a look with innocent curiosity where no one has looked”, as Ulmer explained to Tagesspiegel: Are anti-protons antennas that can pick up signals from dark matter? Most physicists suspect that dark matter consists of as yet unknown elementary particles.

Does a hypothetical particle reveal the existence of anti-matter?

One of the most promising particle candidates is a hypothetical particle named "Axion". If these particles actually exist, then maybe - maybe! - interact with anti-protons. Axions could stagger the rotating anti-protons a bit. Similar to how a toy spinning top stumbles when you bump it. And how did the anti-protons actually behave in the Penning traps? Did you see any irregularities in its rotation, its so-called "spin"?

Ulmer and his colleagues have published the results of their experiments in the journal “Nature”. For the Tagesspiegel, the researcher sums it up as follows: “We looked for such signatures, but found no surprises.” It would have been “a great thing”. Because a positive test result might have solved two of the greatest current puzzles in modern physics: There are actually axions as particles of dark matter. In addition, an unexpectedly large interaction of the axions with anti-matter could perhaps have explained why our world today consists of matter.

But Stefan Ulmer and his colleagues are not giving up: “We are currently developing an experiment that will measure 10 times more precisely and with a larger detection bandwidth.” At least the researchers could uncover the mystery of our existence. Because we still don't know why the history of the cosmos fortunately turned out differently than Mephistopheles wished for in Goethe's Faust: “Because everything that arises is worth it to perish; so it would be better if nothing was created. "

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