What happens to milliseconds since epoch when daylight savings time begins/ends?

Question

Milliseconds since epoch represents the number of milliseconds that have elapsed since 1970. At the instant before daylight savings time ends, or when we set the clocks back to 1:00 from 2:00, do the milliseconds since epoch fall back as well, or do they continue?

Another question: If I live in California, US, which is on Pacific (Daylight/Standard) Time, is the milliseconds since epoch the same there as it is in, say, New York, on Eastern (Daylight/Standard) Time?

Answer 1

Milliseconds since the UNIX epoch (January 1, 1970 00:00:00 UTC) aren't affected by daylight savings and timezones as J. van Dijk mentioned.

To answer your 2nd question explicitly, which i think is important to understand UTC itself: if 2 people call System.currentTimeMillis() in Java or new Date().getTime() in Javascript at the same time, one of them being in California and one of them being in New York they should get the same number of milliseconds.

Answer 2

The milliseconds since epoch are not influenced by timezones and daylight saving time (daylight saving time just changed the timezone with -1 / +1).

The milliseconds/seconds since epoch are (always?) in UTC (or GMT + 0).