# Meaning of a remark by Heisenberg: Die “Bahn” entsteht erst dadurch, dass wir sie beobachten

In a paper by Joos and Zeh, Z Phys B 59 (1985) 223, they say:

This 'coming into being of classical properties' appears related to what Heisenberg may have meant by his famous remark [7]: 'Die "Bahn" entsteht erst dadurch, dass wir sie beobachten.'

Google Translate says this means something like 'The "train" is only created when we observe it.' Is "train" really the right translation of "Bahn" here? Should it instead be something like "trajectory?" Can anyone explain what this aphorism means, or provide a reliable translation?

• Let's continue our discussion about the on-topicness of this question in chat or on Physics Meta. – rob Dec 7 '17 at 18:08

• @Qmechanic Yeah, that's kind of what I was trying to get at. Google translate will turn e.g. "mit dem Bahn reisen" into "travel by train", where "train" refers to the railway transportation system and not the vehicle. The naive interpretation of the machine translation Bahn$\to$train is the primary meaning of the latter, i.e. as the vehicle, but in German, as ACuriousMind has confirmed, the link to the vehicle is only via totum pro parte. This confusion over which meaning of "train" is to be used seems to be close to the core of OP's confusion. – Emilio Pisanty Dec 8 '17 at 18:15