This seems to be the Year of the Third Reich for Yale’s Dramat: The fall mainstage was about Hitler’s rise, and the upcoming “Mother Courage” was written by Brecht in exile from Germany during WWII.

But at first blush, World War II doesn’t appear to be the best setting for Michael Frayn’s “Copenhagen”: The development of nuclear weapons for Hitler seems bizarre for a play that’s supposed to illustrate the ambiguity of morality.

“Heisenberg, we weren’t supplying the bomb to Hitler!” Niels Bohr (Joshua Odsess-Rubin ’08) retorts to Werner Heisenberg’s (Christopher Grobe ’05) accusations.

“You weren’t dropping it on Hitler, either,” Grobe shoots back.

In this play, it turns out, there is more than enough culpability to go around.

In 1941 Heisenberg, Nobel laureate, conceiver of the revolutionary “Uncertainty Principle” and head of Nazi Germany’s nuclear energy program, risked everything to pay a visit to his mentor, half-Jewish “father of quantum physics” Niels Bohr, and his wife Margrethe Bohr (Megan Stern ’06).

We know the end result of their conversation — Hitler never got a weapon of mass destruction — but we don’t have a clue what they talked about or what prompted Heisenberg to make such a dangerous visit.

Frayn would argue that Heisenberg didn’t really know either — as with molecular particles, there’s a limit to the probing of human motivation. But that meeting functions as the pebble in Frayn’s labyrinthine, walled-in pond, whose effects ripple outward and bounce back, overlapping and amplifying each other in this cerebral three-person drama about redemption, memory and, of course, physics.

Director Caroline Van Zile’s ’06 rendition of “Copenhagen” is appropriately minimalist. The entire set consists of three chairs sponged the same gray and white as the floor, and the only sound effects are the repeated motifs of a bellpull (signaling the start of the meeting), the sound of waves crashing, and one other auditory effect that is put to such good use it’d be a shame to spoil it here.

The show plays beautifully to the round: The actors move from reunion to conference to impromptu tribunal, pacing inscribed triangles and minor arcs around the circular stage as they haggle over recreating that fateful September (or was it October?) meeting.

Heisenberg is a slightly different figure in each character’s memory of the meeting, but Grobe plays him with such depth that we recognize his cocktail of arrogance, shyness, self-importance and anxiety to be loved/exonerated through all the script’s permutations.

His chemistry with Odsess-Rubin, who plays Bohr as the father-confessor who embraces contradiction in a way Heisenberg can’t, lets us believe in the two as both son and surrogate father and as rivals so diametrically opposed that their best work was done apart from one another.

Stern is slightly weaker than her counterparts. Her character is the one who should add dimension to the play — she is the observer, and as Heisenberg’s “Uncertainty Principle” tells us, we cannot add an observer without introducing new elements into the system.

Margarethe reads jealousy and confusion into an otherwise heroically abstract story; she must be the layman who was brilliant enough to glean the precepts of quantum mechanics from typing up her husband’s numerous drafts and bitter enough to hold Heisenberg’s German nationality against him when avuncular Niels would rather forgive and forget.

But as portrayed by Stern, Margarethe is more sassy than sage — we are convinced she loves Bohr, but her accusations that Heisenberg “didn’t understand physics” seem drawn not from reservoirs of perceptiveness but from spite.

A quibble with all three actors: “Copenhagen” is ultimately a play about a place — a place in time, a place delineated by its relevance to politics and physics, certainly, but a place nonetheless. Odsess-Rubin, Stern and Grobe seem to have little affection for the place, delivering lines about its natural beauty perfunctorily at best, when Copenhagen itself ought to be the most dramatically evoked locale in the play. (That distinction, incidentally, belongs to a post-war Berlin suburb, brought to mind by Grobe’s passionate soliloquy that references, among other things, incandescent dog muck.)

However, all three actors acquit themselves nicely given what is a very challenging script. For one thing, it takes panache to convincingly deliver such clunkers as, “I don’t think anyone has yet discovered a way you can use theoretical physics to kill people.”

As Oppenheimer famously said after Hiroshima, “The physicists have known sin, and this is a knowledge they cannot lose.” And it’s not clear, ultimately, where Heisenberg fits into this milieu. Was he the blindly loyal patriot who was one miscalculation away from developing the A-bomb for the Nazis? The sly tactician who adroitly kept nuclear fission off Fuhrer’s mind? The ultimate dissembler, so in denial he fools himself?

Whatever the answer, Frayn’s conviction that people can’t be measured by observable quantities means that Copenhagen plays out a bit like “The Usual Suspects,” but in this precise meditation on guilt and the fallibility of memory, the stakes are, to quote Bohr, no less than “our children and our children’s children.”

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