# a friday question... a saturday answer

Andy Wardley abw at wardley.org
Sat Apr 4 09:30:33 BST 2009

```Paul Orrock wrote:
> If you have an event that will happen at a future point in time, say 4
> am and you move it to run at 2am that same day, have you moved the event
> forwards or backwards ?

Interesting question.  Brushing aside the obvious answer that it's just a
matter of semantics, I would say that it all depends on your chosen temporal
frame of reference. Or by spacial analogy:

Q: If you have a tortoise at a distant point in space, say 4 metres away and
it walks forward by 2 metres, has the tortoise moved closer to you or
further away?

A: It depends which way the tortoise is facing.

Time, like space, is relative. There are no absolute values, and no preferred
direction of time (although the laws of thermodynamics would like us to think
otherwise).  You can move an event "forward" in your schedule and it will
happen sooner, in the same way that a tortoise pointing towards you will come
closer when it walks forwards.  Your schedule is effectively pointing back at
you in time, so translating an event "forwards" in this temporal frame of
reference results in the event moving "backwards" in another frame of
reference (such as the one that we traditionally use to measure the "time" as
an offset from the birth of Christ/start of the Common Era)

+-----+                          +--------------------+
| You |    <------forward------  |The Tortoise of Time|
+-----+                          +--------------------+

+-----+                          +--------------------+
| You |    -------forward----->  |The Tortoise of Time|
+-----+                          +--------------------+

This raises the interesting question of whether it is possible to fly sideways
through time (silver machine optional).  It is, theoretically at least, if you
formulate time as a complex number (a + bi) and travel in the imaginary
dimension only.  Contemplating what would happen to a tortoise travelling
through imaginary time is left as a exercise for the reader.

A

PS No animals were harmed during the making of this reply
```