Time Bubbles at Nanten

Ever watch one of those science fiction movies where the protagonists get trapped in time bubbles, in which the flow of time moves at different rates?  Well sometimes observing at Nanten is just like that!  We use several VNC’s to control the telescope and instrument.  These are virtual terminals – remote screens from the computers at the telescope that get mirrored onto our local computers.  We type in these and the telescope then does what we tell it.  Moreover, users from all over the world can participate together, and see what is happening.  It makes it possible to run the telescope without having to be there or to stay awake for 24 hours at a time.  This is how Mopra works too, and is the secret behind the success of the Galactic Plane survey we’re undertaking with it.

However at Nanten2 we have an additional problem.  The internet comes in through a satellite link, and the transmission speed is rather slow.  Furthermore, at our base facility in San Pedro de Atacama we also have a slow internet connection.  The result: there is a time lag between the computer screen at the telescope and what we are seeing in San Pedro.  However this time lag can be different for different VNC sessions.  See the picture below:
timebubblesatnanten

The two screens you can see are for two different VNC sessions, running  different systems on the telescope.  Look at the times on the bottom right of each.  One says 18:00:15, i.e. 15s after 6pm.  The other says 5:59:08, i.e. 52s before 6pm.  They are over a minute different.  Yet at the telescope they will be reading identical times!  We’re in a time bubble!  This can makes it very trying to control the telescope, as anything you type has to wait until the session has caught up with real time before its accepted by the terminal and enacted upon by the telescope.  Even stranger is that a colleague might have the same VNC open on their terminal beside you, or in our case in Cologne in Germany, and they are reading a different time.  And of course seeing a different display relevant to that time on their clock!!  We can be chatting via Skype, but they are seeing a terminal further ahead in time than the one you are watching.  Today we had time shifts of up to 2 minutes between Chile and Germany when trying to diagnose a problem.  Can make for some interesting conversations!  Their present is your future, as well as the telescope’s past, all at the same time.  Get that?!

Just to add further to the confusion, these times are actually UT (Universal Time).  Chilean local time is shown on the top right hand corner of the screen: 17s after 3pm in this case.  But in fact Chile is running on summer time, despite it being in the middle of winter.  Most computers cannot actually cope with this as they synchronise their time from an external server, and most of these still think that Chile is on standard time.  So people everywhere in Chile are going around with the wrong time on their clocks and smartphones unless they know how to manually set these to the correct time!

Time travel comes to Nanten!  You don’t have to be in Star Trek to experience it!

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