534 research outputs found
ADM mass in warp drive spacetimes
What happens when a warp bubble has mass? This seemingly innocent question
forces one to carefully formalize exactly what one means by a warp bubble,
exactly what one means by having the warp bubble "move" with respect to the
fixed stars, and forces one to more carefully examine the notion of mass in
warp-drive spacetimes. This is the goal of the present article. In this
process, we will see that often-made throw-away comments regarding "payloads"
are even simpler than commonly assumed, while there are two further, distinct
yet subtle ways in which a mass can appear in connection with a warp drive
space-time: One, that the warp bubble (not its payload) has the mass; two, that
the mass is a background feature in front of which the warp drive moves. For
simplicity, we consider generic Nat\'ario warp drives with zero-vorticity flow
field. The resulting spacetimes are sufficiently simple to allow an exact and
fully explicit computation of all of the stress-energy components, and verify
that (as expected) the null energy condition (NEC) is violated. Likewise the
weak, strong, and dominant energy conditions (WEC, SEC, DEC) are violated.
Indeed, this confirms the community's folk wisdom, and recent (fully general,
but implicit) results of the present authors which closed previous gaps in the
argument. However, folk wisdom should be carefully and critically examined
before being believed, and the present examples for general results will
greatly aid physical intuition.Comment: V1:19 pages; V2: 22 pages. Authors re-ordered, abstract rewritten; 4
references added; improved presentation and discussion; calculations
unaltered; physics conclusions unaltere
- …