The explanation of the world with that certain extra

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The explanation of the world with that certain extra
The explanation of the world with that certain extra

Explaining the world with that extra something

"Kaluza Klein Particles… can be compared to the pants of today's teenage boys, which need to be as baggy as possible without riding down." Who writes so interesting and flippant at the same time? And why should particles postulated by theoretical physicists have anything to do with teenage fashion?

If you want to know, we recommend Lisa Randall's book "Hidden Universes". The title sounds just like the countless books that promise to unravel the secrets of the cosmos, time or the theory of relativity and then don't keep the promise. But far from it: Harvard physicist Lisa Randal presents decent physics, and her world models are seriously discussed in the scientific community.

Your "extradimensional theories" are very attractive to particle physicists; for perhaps one day they will be able to explain why the masses of the elementary particles have the measured values. Gravity can also be included in the theory - which is difficult since gravity is much weaker than the other three fundamental forces of the Standard Model of physics. Roughly speaking, extradimensional theories allow gravity to act in more dimensions than the other forces. It is then about as strong as its three sisters, but is distributed over more dimensions and therefore looks very weak in our three-dimensional subspace.

Whereas it was previously assumed that additional spatial dimensions had to be very small and, in a sense, rolled up, Randall's work proved the opposite. Extra dimensions could be big.

The author particularly emphasizes that her theories can be tested empirically, as befits a scientific theory. And in contrast to previous string theories, the verification of which would require utopian high energies, this verifiability is not only of a theoretical nature. If the idea of the large extra dimensions is correct, the Large Hadron Collider (LHC), which will soon be operational in Geneva, should find signs of it. Because of this, Randall's ideas are hotly debated. As is so often the case with popular science books, the journey into extradimensional space begins with an introduction to relativity and quantum mechanics.

The statement "just like a centimeter can represent different distances" has to be interpreted correctly as saying that units of measurement are established conventions. A comparison of the quantum statistics with the counting of the votes in Florida for the US presidential election is similarly useless, because the real point disappears into polemics. The comparison of a black hole with the travel opportunities for women in Saudi Arabia is rather tasteless.

Lisa Randall also finds very clear explanations, for example when masses are given in electron volts and units are implicitly converted. She correctly notes that this is basically nothing more than saying the train station is ten minutes away. This example is taken from the middle chapters of the book, where the author explains the Standard Model of particle physics. This part is a readable summary of the current research, with a view to the following chapters on extra dimensions. String theories, Higgs particles and Grand Unification are cleverly introduced and presented as promising concepts. By the end of these chapters, the reader will be convinced of the importance of building the LHC.

Lisa Randall then dedicates the last 120 pages of the 550-page work to the additional dimensions. It introduces many models, whirls around the recently introduced terms and should leave most readers behind. It would probably have been better to simply discuss fewer world designs. Of course, not all of the ideas in these chapters can be relevant to the real world at the same time, and when the LHC gets going it will soon become clear whether any of the author's suggestions describe the world correctly.

The translation of the English physicist's language into German isn't particularly well done. So the expression "weak brane" (in the original "weak brane") sounds really strange for the low-dimensional subspace in which the electroweak forces act. And what does "Tuhdieland" mean? First weres pronounce and heard with English ears ("2-D-Land"), comes behind.

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