Abstract: The talk will describe the production of Copenhagen at the Betty Nansen Theatre, Copenhagen, including the development from rehearsal to performance.

Rehearsing 'COPENHAGEN' at the Betty Nansen Theatre was a very demanding and very exciting journey into a world where none of us had been before.

The closest I had been was when I met Margrethe Bohr in the sixties, and I still remember the kind atmosphere surrounding her, her poise and her smile.

The rehearsals began in the usual way - we had a fabulous play, a very good translation - and we were sitting around a table for some days, going through the text and asking questions.

The theatre had in advance provided us with some books on the subject, and one of them was especially useful: Abraham Pais's book 'NIELS BOHR'S TIMES IN PHYSICS, PHILOSOPHY AND POLITY'. This book gave us much information of the warm relationship between Margrethe and Niels Bohr and told about the terrible accident when they lost their eldest son. We also got some knowledge of many of the physicists we where talking about in the play, first of all WERNER HEISENBERG of course.

After a few days we moved onto the stage where the director had created a dining room area and a sitting room area - very nicely. The dinner table was decorated with candles and flowers and in the sitting room there was even a piano. The director's idea was that before moving into the set, which consisted of only 3 chairs, we should experience the feeling of a real home.

We worked there for some time, moving around in different positions. We then had to move back into the rehearsing room. The director had decided that it was very important that the audience was sitting as close to us as possible, so they created a new stage floor on the level of the lower edge of the balcony, above the space where the audience would normally sit - they made a second balcony in the empty stage room, facing the other one, and from balcony to balcony on each side two rows of seats were built. Under the ceiling was placed a huge semi-globular lamp - the atomic explosion in the end took place there - and there were tiny lights in the floor all the way round the stage.

Well, we knew something about the Bohr family, Heisenberg and some other physicists, but what about QUANTUM MECHANICS, the uncertainty principle and the relativity theory?

We decided to visit the Danish Museum of Electricity where there was an exhibition about Niels Bohr and his work. We caught a train for Jutland, had our own compartment so we were able to work during the 5-hour journey.

Being there our kind and patient guide, who was also a physicist showed us around in the Museum, we saw funny little lights circling and many other things, and asked him how and why. Sometimes we got an answer, but sometimes he said: 'Yes, there we have a problem.'

Concerning the historical aspects: Two of us had lived through the German occupation of Denmark in world war two. We knew how difficult it would have been if a German friend had knocked on our door.

Another thing I remember is that the director asked me to look at Heisenberg from the very beginning of the play. And for a long period I refused. I can't do it, I said, he is on the stage, but he hasn't come to us yet. I can't look at him when he isn't there? But the director repeated, 'try! try!'. And then a moment came when I said to myself - the director is sitting in the audience, he might observe something which I am unable to feel from here, and so I looked at Heisenberg, although I didn't agree.

But then, during the first previews before an audience, I felt it was right - that Margrethe Bohr, with her look in a way introduced the reservation she felt against Heisenberg and his visit - it emphasized the dramatic tension. This was what the director intuitively sensed without being able to express it precisely.

In this way - I believe - both actors and scientists, in some cases, work intuitively without being able to put it into words. They come later on, along with the results.

Two nights I remember with a special feeling. Michael Frayn and his wife had planned to be there at the premiere, but we had to postpone it a few days and Michael and his wife couldn't stay that long. So we did a performance for them alone. That was very special. Another night I clearly remember was when Niels and Margrethe Bohr's son Hans Bohr was there with some members of his family.

Being in this play was a beautiful task and a wonderful experience - maybe one of the best in my life in the theatre.

Lily Weiding, SEP. 2001