What was Einstein's approach to problem solving

general theory of relativityBeyond Einstein

"The general theory of relativity is now a hundred years old. Everything we can measure and see over great distances can be explained with it."

In fact, Einstein's formulas have almost visionary qualities. They proved this for the first time at the end of the twenties. The US astronomer Edwin Hubble measured the speed and distance of the galaxies in the sky. It turned out that the further away the objects are, the faster they race away from us. Cosmologist Jim Peebles teaches at Princeton University:

"This suggests that the universe is expanding - and that it once had a very dense, hot origin: the Big Bang. We can understand very well how the universe has developed since then. We use general relativity for this.

Albert Einstein originally developed his formulas with a few observational findings and a lot of philosophy. The theory had passed all the tests in our solar system perfectly - and then even in the depths of the universe a lot fit the model very well. That was amazing! "

When Einstein formulated his theory, the astronomers were still living in the cosmic idyll. Much more than the Milky Way was not known - and so Einstein also assumed that the universe would be the same forever. Edwin Hubble's observations shattered this notion, just as Galileo Galilei's discovery of the mountains of the moon and Jupiter's satellites shattered ancient ideas about the structure of the world. But while Galileo brought the old geocentric world model to its knees, the expanding universe was not the death knell for the theory of relativity, but its accolade, explains Joachim Wambsganß, director at the Center for Astronomy at Heidelberg University:

"It is amazing how this young man Albert Einstein managed at that time to describe the phenomena of nature, which were not even known, so magnificently."

"Why can't you be satisfied with this state of affairs?"

A universe that is expanding and thinning itself further and further. Einstein's equations predicted just that. Only Einstein himself hadn't wanted to believe in it. Completely absurd, he said and artificially settled his theory, expanded the equations in such a way that the universe became static as desired.

"That was the biggest donkey of my life ..."

... the great physicist is said to have growled when he heard Hubble's observations and restored his theory to its original form. The rules of gravity had even outstripped its creator. In the decades that followed, many more observations of very different phenomena in the cosmos were made, all of which fitted perfectly with the relativistic predictions. And yet in retrospect it is clear that the discovery of the Big Bang and the expanding cosmos was the beginning of the very slow end of the theory.

In the twenties - only shortly after general relativity - physicists also formulated quantum theory. While Einstein's set of rules described the cosmos, i.e. the world of the very big, quantum mechanics started in the world of the very small, with the atoms. Both theories are based on completely different approaches. Worse still, they contradict each other on certain points.

"God does not play dice!"

... once scolded Albert Einstein. He didn't like the fact that quantum theory doesn't allow exact predictions, unlike its relativity. The contradictions hardly bothered anyone at first - the theories literally avoided each other. It was only over with the Big Bang.

"At first there is no compelling necessity, one would think, because general relativity is responsible for the vastness of the cosmos, and quantum theory is responsible for the microcosm. In their areas, both theories work very well, extremely well, you can even say Quantum theory is certainly the best-tested theory in natural science. One can then ask the question: Why cannot one be satisfied with this state of affairs? "

Hermann Nicolai, one of the leading theoretical physicists of our time, is director at the Albert Einstein Institute, the Max Planck Institute for Gravitational Physics in Golm near Potsdam.

"Physically, it is already suggested by the fact that we know that the universe is expanding. If we calculate the whole thing back, we arrive at a point where everything was compressed into an extremely small volume, where space and time themselves were only created . And if you want to understand that, then you have to understand how quantum theory and relativity theory fit together. "

At the very beginning, in the first ludicrously small fraction of a second after the Big Bang, the entire cosmos was so small that only quantum effects shaped what happened. At this point in time, gravity did not play a role, but a short time later it was determining the fate of the universe. Hermann Nicolai and his colleagues all over the world try to explain how our modern world full of planets, stars and galaxies grew from a hot, tiny initial state using string theory. This model, which combines quantum mechanics and relativity theory, could almost become a "world formula". But the guild of researchers grit their teeth on the chunk.

"String theory has been around since 1970. But the theory is so complicated that even today we don't know whether it actually fits nature or not."

A mistake in Einstein's theory?

Scientists are in a most uncomfortable position. They know that quantum and relativity theory cannot be the ultimate answer. But these theories have proven extremely robust in all tests. There are still no observations that apparently contradict them. In 2002, Luciano Iess from the Roman University of La Sapienza participated in the most accurate test of the theory of relativity to date. His measurements matched the predictions with an accuracy of 0.02 per thousand. Iess could have been disappointed.

"I was relieved! Just imagine if we had measured a deviation from the theory of relativity. That would have been a huge deal, but we would have had great problems getting our work published. Because of course another research group should have confirmed this. We would have had but at first nobody believed. "

That is almost absurd: the physicists know that Albert Einstein's conceptual structure needs at least one addition - but the researchers are afraid of the discovery and are happy if the big coup does not succeed. It is only a matter of time before the monument falls.

"There are no absolute truths in physics. One can only approach the truth gradually."

Before Isaac Newton, many scholars believed that celestial bodies moved because of magnetic effects. Newton, on the other hand, postulated: Matter attracts and forces act between bodies. His law of gravity ruled for more than two centuries. Until Albert Einstein came up with the idea that space and time are not an immutable framework of the cosmos. Instead, matter should change space-time itself, which in turn had to influence the movement of bodies. What will the next radical change be?

"Obviously something is still missing in our worldview."

"We'll probably have to think from scratch to discover it."

An observation that clearly contradicts the predictions of the theory of relativity would be an important clue. It is forcing physicists to finally leave the beaten track. This observation may long have been made - for more than eighty years.

"In the 1930s it was noticed that stars in galaxies and galaxies in galaxy clusters move at a greater speed than should actually be the case according to the theories of Newton or Einstein."

A mistake in Einstein's theory? The excessive speeds allowed a second conclusion: Perhaps there was dark matter out there, in other words, matter that does not shine, but only attracts.

"Fritz Zwicky, a Swiss-American astronomer, called it the missing matter or missing mass."

To this day, almost all astrophysicists support Zwicky's explanatory approach. Michael Turner, a cosmologist at the University of Chicago, is now also dealing with a universe full of mysterious dark matter that cannot be seen in any telescope in the world - but is apparently directing powerfully behind the scenes.

Those who deal with alternatives are less likely to be invited to conferences

"Dark matter is a whole new form of matter. Most of the material universe consists of something other than the atoms we are familiar with."

The invisible masses are not supposed to be made up of extinct stars, black planets or cold dust clouds, but hitherto unknown particles. At least that's what the theory demands.

For decades now, particle physicists have been trying to find any trace of dark matter in their detectors - so far in vain. And with each unsuccessful experiment, the alternative explanation becomes more likely:

Einstein's theory is wrong.

In fact, there is a small group of scientists who are concerned with other theories of gravity than just Einstein's general relativity. The most intense discussion is an approach called MOND. MOON says goodbye to the idea that gravity is the same everywhere. Where the forces of attraction are small, today's law of gravitation could no longer apply.

"The Modified Newtonian Dynamics, MOON for short, goes back to Moti Milgrom in 1983. I came across this theory when my galaxy models no longer worked. MOND predicted exactly what I was observing within the framework of traditional theory but couldn't explain. "

Stacy McGaugh of Case Western Reserve University in Cleveland, USA, has worked with the standard cosmological model for years, but is now also investigating alternatives. With that he goes on smooth parquet. Many researchers find the MOON approach too artificial, because there is no fundamental physical reason why gravity should suddenly change - but there is also nobody who would argue against it. There are only a few dozen researchers in the world who do MOND research - and whoever does this has to put on a rather thick skin when contacting colleagues.

"Many, but not all, react very negatively. I can understand that well, because in the past I didn't want to believe that the MOON model could work either. I also grew up with the idea of ​​dark matter. It was completely clear to me that that this stuff exists. "

Anyone who deals more intensively with alternatives to Einstein's theory and its dark matter is invited to conferences less often and is sometimes considered a "weirdo". So far, only one researcher with MOND experience has received a professorship. Usually, Stacy McGaugh complains, younger colleagues are advised not to take this idea too seriously if they do not want to jeopardize their careers.

"Unfortunately, the dispute already has a religious connotation, almost like it once did in the fight for the geocentric or heliocentric universe. They were completely different approaches. A lot of observational data matched both of them. But they were fundamentally in contradiction - and the followers fought each other Deviants even burned. "

Stacy McGaugh and colleagues rightly point out the weaknesses in the Standard Model. But it is by no means certain that their new theory is more than messing around. In any case, the MOON approach crashes through many tests, explains Michael Kramer from the Max Planck Institute for Radio Astronomy in Bonn. He tests Einstein's theory and its competitors with pulsars, compact star corpses:

The universe is diverging faster and faster

"It is very important to check other theories as well. ... Often these alternative theories are set up for very special purposes, for example to explain dark matter and dark energy and very often people do not think of other areas where the theory Of course, it also has to apply. If the theory explains dark matter, for example by changing the law of gravity, does this theory then also correctly describe the motion of pulsars? "

As if the mystery of dark matter wasn't big enough, there is pressure from another side. In the 1990s, astronomers wanted to measure how the mutual attraction of matter in space slowly slows down the expansion of the cosmos, just as a stone thrown upwards is slowed down by gravity until it falls back again. Once again, the experts were completely surprised: there was no question of a slowdown.

"In the last few years there have been a number of discoveries that indicate that the expansion is not only not slowing down, but is even accelerating, that all matter in space is repelled from one another by a kind of negative pressure. This will be done summarized under the term dark energy. That may not be physically correct, but it is a catchy name, and the astronomical community immediately adopted it. "

The universe is diverging faster and faster, driven by an ominous dark energy. Your nature: unknown. Then there is the dark matter, which, despite an intensive search, has still not gone online. A catastrophic result: 95 percent of the content of the universe is misunderstood.

"These are the two outstanding puzzles in cosmology or in general in physics: If dark matter really exists, what particles does it consist of? And which processes are responsible for dark energy?"

Dragan Huterer comes from Sarajevo, studied with Michael Turner in Chicago and is now researching the nature of dark energy at the University of Michigan. The theorists cheered at first that the universe should expand at an accelerated rate - because the "cosmological constant" is experiencing a grandiose comeback due to the dark energy. The size with which Albert Einstein once trimmed his general theory of relativity to a universe at rest and which he had considered to be the biggest mistake of his life.

"At the moment, the dark energy looks like a cosmological constant. This Einsteinian addition now ensures the ever faster expansion that we observe in space. The cosmological constant corresponds to the vacuum energy in the universe."

This also brings quantum mechanics back into play. Quantum theorists have long known that the vacuum, literally nothing, has an energy. Now the traditional antagonist of relativity is giving cosmologists a crushing defeat. Dragan Huterer:

"We can calculate the vacuum energy with the help of quantum mechanics. This is the most successful theory of our day. It provides a value for this dark energy in the cosmos that is over 100 orders of magnitude higher than the value observed in space. That is an insanely large number: a one." with 100 zeros. "

The worst prediction in all of physics

Theory surpasses reality by this unimaginably large factor: It is the worst prediction in all of physics. Now the researchers are feverishly looking for a way out of the confused situation.

"One of our goals is to find any deviations from the scenario of cosmological constants. We measure how quickly galaxies are formed, what large-scale structures they form, how rapidly the cosmos is expanding, whether it slowed down in the past and then accelerated again, and so on . By comparing as many different observations as possible, something can be said about dark energy and dark matter. Of course we don't know what nature will bring us. "

The young cosmologist wants to provide facts that will finally cause major cracks in Einstein's ideas. He considers the fact that it cannot explain 95 percent of the cosmos to be completely unacceptable.

On the other hand, others make themselves comfortable in the absurd world and cultivate the inflation theory. According to her, the cosmos expanded explosively a fraction of a second after the Big Bang - later the expansion continued at a normal pace. This rather arbitrary approach elegantly explained more than thirty years ago that the universe looks roughly the same everywhere, which could not be understood with Einstein alone. With a little mathematical effort, inflation brings relativity and the mysterious 95 percent of the cosmos under one roof - but its creators fare like the sorcerer's apprentice. They can no longer get rid of the spirits who called them:

"Inflation theory does not predict just one universe. The same mechanism that gave birth to our universe should produce many more universes - infinitely many. In this multiverse there would be every single type of dark energy. But people who have Thinking about dark energy only arises when the energy is very small. "

Alan Guth from the Massachusetts Institute of Technology, one of the inventors of inflation, uses a nifty argument: If the dark energy were significantly larger, space would fly apart much faster - galaxies could not have formed in the first place, and thus also no astronomers who are overlapping today who wonder so tiny little dark energy. Paul Steinhardt from Princeton University, once involved in the development of this theory himself, can only shake his head:

"My biggest objection is that inflation is extremely flexible. It can explain practically all kinds of observations. Because it is extremely sensitive to pre-inflation conditions - if you change them a little, very different things come out immediately. There are none Test that could refute inflation. In doing so, we are crossing the line from natural science to metaphysics - and that makes it scientifically meaningless. "

Scientific knowledge as a democratic process

What a crazy situation: The theory of relativity drives the researchers to despair because it passes all the tests with flying colors. Many cosmologists cheer about the inflation theory because it predicts everything - and therefore nothing. But Alan Guth is extremely sensitive to this accusation:

"I believe that anyone who takes a serious look at the history of science realizes that Karl Popper's old idea of ​​rebuttable theories is obsolete. Then you should test a theory, test it and test it again and again until you find an experiment that does not fit the theory and thus excludes it, but science no longer works that way today.

Rather, science today is an arena of competing ideas. And right now, inflation is by far the most widely accepted theory in cosmology. Maybe someday you will find something better. There are, of course, many variations on this theory, but the simplest models of inflation fit the data so nicely that I don't think we can go wrong with them. "

Scientific knowledge as a democratic process - an absurd attitude. For millennia, almost all scholars have agreed that the earth is at the center of the world and is orbited by the sun. But, as is well known, this had nothing to do with reality ... When it comes to inflation, some are already talking about the epicycles of modern times - that grandiose construct of nested circular orbits that the ancient Greeks used to describe the movement of the planets around the Justify earth in the center. Mathematically very elegant, physically worthless.

Cosmologists are often wrong, but they never have doubts, the Russian astrophysicist Jakov Zeldovich once sneered at his craft. Joachim Wambsganß does not find the current situation frustrating, but rather inspiring:

Cosmology needs someone like Johannes Kepler again

"I have no problem with the fact that we don't understand everything yet. Perhaps in 50 years time people will laugh at our ideas of dark matter and dark energy just as we smile at the physicists who talked about the world ether at the end of the 19th century, which according to the ideas of the time should flood the world. It should be transparent like a vacuum, but at the same time have mechanical properties like steel. That was not solvable. Einstein solved this problem with his general theory of relativity in one fell swoop. "

Once again, cosmology needs someone like Johannes Kepler - or Albert Einstein. One of them sent the planets on elliptical orbits, which was just as revolutionary then as Einstein's new theory of gravitation a hundred years ago. Who will now manage to lead physicists out of the impasse? And what will our picture of the world look like then?

In Newton's theory of gravity, which seemed beyond doubt for more than two centuries, for a long time there was only one harmless little thing that contradicted the theory: the orbit of the planet Mercury, the closest to the sun. This disagreement cleared up in a way no one expected:

"The theory that explained the motion of Mercury wasn't just Newtons and something more. It was something completely new - Einstein's theory of relativity! I am personally convinced of the existence of dark matter and dark energy. But we may be with the Big Bang and Inflation on the wrong track. We finally have to somehow understand what's going on out there. Perhaps a much bigger revolution awaits us than we imagine today. "