# Minimum Amount of Negative Energy required in Warp Drive Spacetimes

In the pioneering work of Alcubierre, to power a warp drive-like geometry it is necessary to employ an amount of negative energy larger (in absolute value) than the whole observable universe mass. A later refinement by Den Broeck brings the requirements down to few solar masses.

What is the current minimum amount of negative energy required to build a warp drive-like spacetime? (with link to the reference please)

• The Wikipedia article discusses the various exotic mass requirements. A common figure given these days is around Jupiter's mass. – PM 2Ring May 5 at 20:47
• @PM2Ring Are there any compelling reasons to think that any exotic mass suitable for an Alcubierre drive could be created, or is it just wishful thinking that such a thing could exist? If it is just wishful thinking, then I will vote to close this question as non-mainstream physics. – G. Smith May 5 at 20:53
• @G.Smith Personally, I'm extremely sceptical that negative mass exotic matter can exist. But there are quite a few unclosed questions in the warp-drive & exotic-matter tags, so I guess it's considered borderline, rather than definitely non-mainstream. – PM 2Ring May 5 at 21:08
• @G.Smith: Are there any compelling reasons to think that any exotic mass suitable for an Alcubierre drive could be created, or is it just wishful thinking that such a thing could exist? There isn't a simple answer to your question. Relativists don't really talk about negative energy, they talk about energy conditions, and there are a bunch of different energy conditions. We pretty much know that none of the energy conditions are universally valid, but we also expect them to hold in bulk matter. A nice summary is Barcelo and Visser, arxiv.org/abs/gr-qc/0205066 – Ben Crowell May 5 at 21:58
• @PM2Ring Thanks for your link, but I'm not able to locate the details of the calculations yet. – Rexcirus May 6 at 8:53

According to this paper by Krasnikov, the energy requirement can be brought down to approximately $$10^{-3} g$$ for a human-usable warp drive: