Mathematics in the underground, 2016

By on 19/10/2016

In the proseminar “Mathematics for the general public” at Freie Universität Berlin (by Professor Behrends, summer term 2016) activities for July 18 and 19, 2016 were prepared. These were the first two days of the European congress of mathematicians 7ECM that took place in Berlin for the first time, and at this occasion some interesting aspects of mathematics should be explained to as many as possible contemporaries.

Several themes that could be suitable for this purpose were discussed in the proseminar. Always there was a mathematical part and a “popular extract”. For example, after a talk on cardinal numbers “Hilbert’s hotel” was extracted.

We concentrated on the following aspects:

  • “mathematics inside”: mathematics a places, where most people would not have expected it (mathematics and art, mathematics and music, cryptography, …)
  • Unexpected phenomena (birthday paradox, surprises when inverting conditional probabilities, Hilbert’s hotel, …)
  • Recreational mathematics (mathematical magic tricks, …)

Our actions were planned to take place between 10 am and 4 pm at these two days in the underground stations Wittenbergplatz, Potsdamer Platz and Alexanderplatz in Berlin. It was surprisingly easy to get the permission of the authorities.

In the week before our activity there was a press release of Freie Universität, and really there were some radio reports and newspaper articles announcing the event.

Now we could start. Some colleagues from Berlin and some European countries collaborated with us, and all preparations were done in time. Each of the three teams had special T-shirts, a roll-up poster, a flip chart and printed material with some background information on the themes to be discussed.


The roll-up poster with some invitations: magical mathematics, exponenential growth on the chess board, cryptography, art, Hilberts hotel, lotto, music.

Here are some pictures:











We start! Our preparations at Wittenbergplatz










Mathematics and music … and mathmagic …










The birthday paradox demonstrated with the 23 participants of some games of the European championship 2016.

The birthday paradox demonstrated with the 23 participants of some games of the European championship 2016.


Afterwards in the restaurant "Luise":

Afterwards in the restaurant “Luise”:

Our summary: We met really a lot of people, and many of these meetings were very interesting. As a rather sad fact it turned out, that many contemporaries can hardly be transformed to enthusiasts of mathematics. (The situation was rather different with other public awareness experiences. For example, when being active at the “Long night of science” one has a bigger chance to meet people open for mathematics.)

Nevertheless it was very interesting to leave the “ivory tower”, in particular since most of the participants of this proseminar will be teachers in their professional life.

E. Behrends

About Ehrhard Behrends

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