Question

In Einstein's original thought experiment involving a (very long) train running along a [straight] railway embankment, of essential importance appears the prescription that

[E]very event which takes place along the [railway track] line also takes place at a particular point of the train.

The constituents of the train are surely distinct from the constituents of the railway embankment and track (especially since they are supposed to have moved wrt. each other; each constituent of the train and each constituent of the track segment under consideration have separately met each other in passing).

Is it consequently correct to say that each separate event involving train and embankment/track has one particular constituent of the train and one particular constituent of the track as participants in this event, such that this particular pair uniquely identifies the event ?,

and that each such event has two distinct parts, namely

one distinctive part attributable to the participating train constituent (which is characterized by the train constituent indicating being met, in passing, by the track constituent; perhaps with additional characterizations), and

another distinctive part attributable to the participating embankment/track constituent (being vice versa foremost characterized by the track constituent indicating being met, in passing, by the train cconstituent)?

Note that the event-parts in question are not presumed to be separate from each other, or resolvable, in a geometric (spatial) sense. My question is not whether and how certain sets of (finely-resolved) distinct events may be considered and addressed as one (coarsely-resolved) event; nor whether any one actual particle (or even several) may be considered fully contained in any spacetime region of finite spatial extent.

My question is rather conceptually:

Whether (at all) and (if so) How to reconcile

speaking of an event as having distinguishable parts, as described above, while also

speaking of an event as a point in spacetime, or a point of spacetime with the understanding that: A point has no part(s).

Answer 1

In Einstein's thought experiment, each event involving the train and the track is considered to have one particular constituent from the train and one from the track, which uniquely identifies the event. These events can be conceptually divided into parts attributable to the train and track constituents, although they do not have spatial parts.

Step-by-step explanation:

In Einstein's original thought experiment, the train and the railway track are considered as two separate entities.

However, each event that takes place along the railway track is also considered to take place at a particular point on the train.

This means that each event involving the train and the track has one particular constituent from the train and one particular constituent from the track as participants.

These specific pairs of constituents uniquely identify each event.

Each event has two distinct parts: one part attributable to the train constituent and another part attributable to the track constituent.

Although the event-parts are not separate or resolvable in a geometric (spatial) sense, they can be conceptually distinguished.

It is important to note that an event is considered a point in spacetime and does not have spatial parts.

owever, when discussing the constituents involved in the event, we can conceptually think of them as having distinct parts.