the people didn’t begin to jump until after they were already inside the train

[diamondcutter]

Because "in" does not itself express or evoke an image of a boundary being crossed, (9a) could mean that the people didn’t begin to jump until after they were already inside the train (as in We jumped for joy on the platform and they jumped for joy in the train). In contrast, example (9b) is unambiguous about movement from the outside to the inside.
(9) a. They jumped in the train.
b. They jumped into the train.

Source: English Prepositions Explained Revised Edition by Seth Lindstromberg

...the people didn’t begin to jump until after they were already inside the train...

Is the word “after” in this sentence used correctly? I mean whether we should remove it because the conjunction "until" here means "before".

 

[emsr2d2]

"After" is redundant, as is "already".

The people didn't begin to jump until they were inside the train. (It would be more natural to say "on the train".)

9a means they were on the train and then they jumped (up and down).
9b means that they jumped from the platform onto the train. (Note that "onto" is more natural than "into" there.)

 

[jutfrank]

The use of after is for emphasis. The writer wants to make the meaning very clear.

 

[Phaedrus]

...the people didn’t begin to jump until after they were already inside the train...

Is the word “after” in this sentence used correctly? I mean whether we should remove it because the conjunction "until" here means "before".

The people didn't begin to jump until they were inside the train. --> Once they were inside the train, they began to jump.

The people didn't begin to jump until after they were inside the train. --> They got inside the train, and some time may have elapsed before they began to jump.

Compare: The people didn't begin to jump until well after they were inside the train. --> A substantial amount of time elapsed between the entering and the jumping.

 

[jutfrank]

The point is simply that the jumping can be interpreted to take place entirely in the train as opposed to into the train from the platform.

The use of after is just a way of making that clear. It doesn't matter how much time elapsed.

 

[Phaedrus]

The point is simply that the jumping can be interpreted to take place entirely in the train as opposed to into the train from the platform.

The use of after is just a way of making that clear. It doesn't matter how much time elapsed.

Be that as it may, "after" is not only grammatical in "until after" but contributes meaning, as the construction "until well after" demonstrates.

He didn't do X until Y indicates that Y led to X fairly immediately.

He didn't do X until after Y indicates that Y and X were separated in time.

He didn't do X until well after Y indicates that Y and X were substantially separated in time.

 

[jutfrank]

Be that as it may, "after" is not only grammatical in "until after" but contributes meaning, as the construction "until well after" demonstrates.

Sure.

He didn't do X until Y indicates that Y led to X fairly immediately.

I say that there isn't any time between X and Y, psychologically speaking. Psychologically, they both represent identical points in time.

However, when we say things like:

They didn't have sex until they got married.

we don't mean that they had sex exactly at the moment they kissed in the church. But my view is that psychologically, both events coincided. I believe you can see this more clearly when the point in time is dilated. Consider:

He didn't start walking until last year.

The time phrase last year here is a point in time psychologically and linguistically speaking although it's obviously a measurable period of time, physically speaking. We don't mean he started walking on the first day of the year. The time frame that frames an action or state expressed by a verb phrase Y in a clause preceding until leads right the way up to the point in time where action/state X takes place.

The phrase until now is a good example that shows 'now' to be represented in the mind as a 'dilated' point in time. The idea of 'now' is represented as a point in psychological time even though we use it to refer to what is measurably a passage of time . I'm convinced the distinction between psychological time and physical time is absolutely crucial in understanding how linguistic aspect works. Not only that, I think it has confused many a philosopher, too, but that's another story ...

 

[Phaedrus]

I say that there isn't any time between X and Y, psychologically speaking. Psychologically, they both represent identical points in time.

However, when we say things like:

They didn't have sex until they got married.

we don't mean that they had sex exactly at the moment they kissed in the church. But my view is that psychologically, both events coincided.

I agree with you, Jutfrank. What an excellent and hilarious example you have used to illustrate the point!

It is interesting to think about durative (non-punctual) situations in the "until"-clause. Consider these sentences:

(i) He didn't take calculus until he took trigonometry.
(ii) He didn't take calculus until after he took trigonometry.
(iii) He didn't take calculus until he had taken trigonometry.
(iv) He didn't take calculus until after he had taken trigonometry.

I'd say that (i) implies that he took (and started) calculus and trigonometry simultaneously, whereas (ii), (iii), and (iv) indicate that he took trigonometry first and calculus second. Sentence (ii) indicates this by means of "until after," and (iii) by means of the past perfect in the "until"-clause. Sentence (iv) uses both indicators, redundandly. We could make it even more redundant by adding "already": "He didn't take calculus until after he had already taken trigonometry." What I find interesting, though, is that neither (ii) nor (iii) contain any redundancy: "until after" signals the same thing that the past perfect does.