Why does gravity bend space

100 years of general relativity : Mattress for heavenly bodies

Albert Einstein superstar. These days there is another reason to celebrate. 100 years ago, on November 25, 1915, he presented his general theory of relativity to the public in Berlin. It is a collection of formulas from the essence of the world that was so ingenious and at the same time so inexorable towards earlier theories that it must be considered a revolution in physics. It swept away supposed certainties radically. Space and time have been fixed values ​​since time immemorial. They formed the coordinate system in which every individual, every act, even every thought can be located: with a clear place at a clear time. In a sense, an address that everyone can read and find.

Space and time were no longer a rigid grid

Not exactly! Einstein had shown this in 1905 with his special theory of relativity. She explains that intervals and time spans are not constant, but depend on the observer. That a clock in a fast spaceship, for example, runs a tiny bit slower than it does on Earth. Ten years later he added gravity. Space and time were no longer a rigid grid that could be placed in the universe for orientation. They were brought together to form “space-time”.

You can imagine it like a checkered mattress into which heavenly bodies sink. The more mass they have, the deeper the dent, the more clearly the originally even checkered pattern of spacetime is curved. This means, for example: On earth, clocks run a tiny touch slower than on a probe that flies out in space far from earthly gravity.

Culture of skepticism

Space and time and gravity have to be thought together, that was Einstein's central message. But could you believe him? With every astronomical observation that confirmed his theory, the doubts diminished and the respect for the researcher grew. His concept has been around for a hundred years. In modern physics, with its extensive possibilities for experimentation and a culture of skepticism, this is a respectable time and thus a strong indication that Einstein's theory of relativity is really true.

Today it is regarded as a kind of world formula, at least for the macroscopic one - it can describe how the universe works on a large scale. That the universe began with a big bang and continues to expand, which was only proven much later. But it also helps us in everyday life by providing corrections for GPS measurements, for example, without which satellite navigation would arrive at a deviation of eleven kilometers within 24 hours.

Einstein, rock star of science

Of course, the theory of relativity also owes its fame to its spiritual father, the greatest rock star in science. Einstein was a provocateur who didn't give a damn about the venerable Newton and other giants in his field. Why not? After all, he had developed a number of groundbreaking theories that advanced physics significantly, which distinguishes him from Stephen Hawking, for example. He had a tolerably exhausting and wild life, which made it easier to identify with him, and politically and morally he was almost always on the right side.

Above all, however, he is considered to be the last great universal genius: someone who really still had an overview and was still able to immerse himself in a wide variety of topics. It wasn't that easy for Einstein after all, according to recent research. So he begged a young mathematician for his theory of relativity: “Help me, Grossmann, or I'll go crazy!” He helped, like many others. Einstein survived alone in the collective memory.

One or one alone will not find the solution

Today the contributions of fellow researchers are more visible in science. That may diminish the team leader's shine a bit, but it is more in line with reality. Regardless of whether it is about the discovery of the Higgs particle, which thousands of researchers succeeded in at the LHC particle accelerator, or the measurement of neutrinos in deep mine tunnels or the ice in the Antarctic - the major research questions of this time are so complex and require so much technical effort, that great progress can only be achieved with many people who put their hearts and minds into the cause.

This gives hope for an expansion of Einstein's theory of relativity. It is necessary in any case, because it can only explain one of four basic physical forces, gravity. The electromagnetic, strong and weak interactions, which take place primarily on the micro level, are left out. A solution is not yet in sight. But one thing is clear: one or the other alone will not find it.

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