Alcubierre's goose is roasted by Hawking's radiation

[marcus]

http://www.technologyreview.com/blog/arxiv/23292/
http://arxiv.org/abs/0904.0141
Thx to Swans on Tea

 

[Coin]

Bad news I'm afraid -- it looks as if faster-than-light travel isn't possible after all.

*sighs, cancels summer travel plans*

 

[scibuff]

*sighs, cancels summer travel plans*

Alcubierre's drive does NOT allow velocities greater than c. What it does (in a nutshell) is it affects the space-time so that the distances are (much much much) shorter. But locally, within the warp-bubble, you don't travel faster than light. In fact, a traveler inside the warp bubble experiences a free fall (feels no acceleration) it is the space-time itself that affects your world line, effectively changing your position. Great advantage of this design is that there is no need for "inertia dampeners" since you feel no acceleration.

 

[marcus]

*sighs, cancels summer travel plans*

Alcubierre's drive does NOT allow velocities greater than c. What it does (in a nutshell) is it affects the space-time so that the distances are (much much much) shorter. But locally, within the warp-bubble, you don't travel faster than light.

What is your point, Buff? Your post does not seem to be connected or relevant to the MIT Technology Review article, or to the piece by Stefano Liberati.

What the article appears to show is that the particular type of "warp-bubble" (assuming it could be produced) would be unstable and/or would kill any traveler inside it. The present authors claim earlier analyses of the "bubble" were inadequate and to have made a more realistic analysis. They found that the problem was with the bubble itself (e.g. it would fill up with Hawking radiation.)

In fact, a traveler inside the warp bubble experiences a free fall (feels no acceleration) it is the space-time itself that affects your world line, effectively changing your position.

What the traveler experiences or does not experience inertia-wise is irrelevant if it is unstable, as the authors suggest, or he is being roasted alive with radiation from the "bubble" walls.

I should say that "bubble" space-travel ideas are not an interest of mine. I just posted this for comedy. And in case others, like Coin, might be interested. It seems to have affected his vacation plans .

 

[scibuff]

I was really replying to the

"Bad news I'm afraid -- it looks as if faster-than-light travel isn't possible after all."

, but quoted the wrong part of the post :D, my bad

 

[marcus]

I see. The lead sentence of the MIT Technology Review popularization of the scientific article by Stefano Liberati et al.
Well in the sense you interpret it, that is not what is being discussed.

Stefano et al article is about the structure of the "warp-bubble". This might be a good time to put Liberati and the INTERNATIONAL SCHOOL OF ADVANCED STUDIES (sissa) on the map for anyone not familiar with them.

Here is a list of Liberati's professional publications (80 so far):
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+LIBERATI%2CS&FORMAT=WWW&SEQUENCE=

Here is the same list ranked by numbers of citations
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+LIBERATI%2CS&FORMAT=www&SEQUENCE=citecount%28d%29
One sees that 7 of his papers have received 100 or more citations
and you see the kind of people he has co-authored with.

The SISSA is one of Europe's top research institutions for theoretical physics. It is located at Trieste. The acronym is Italian for "international super-school of advanced studies".
http://www.sissa.it/main/?p=SECTOR
They list their main research sectors as:

Astrophysics
Cognitive Neuroscience
Condensed Matter Theory
Elementary Particle Theory
Functional Analysis and Applications
Mathematical Physics
Neurobiology
Statistical and Biological Physics

I know of them primarily through the connection with astrophysics, cosmology, general relativity, quantum gravity, unified theories. They trade postdocs back and forth with the Max Planck Institutes in Germany, the AEI-Potsdam in particular. I know they are good in the areas I watch---I don't know how they are in the other areas they list.

Liberati is 38. He was born December 1970. He has co-authored a lot with Ted Jacobson. Also with Matt Visser and Bruce Bassett. World-class in other words. Lots of honors etc. Here's Stefano's homepage.
http://people.sissa.it/~liberati/

BTW another person at sissa whose work I watch is Roberto Percacci. He wrote the chapter on asymptotic safety in the new book, Approaches to Quantum Gravity, that just came out.

Anyway this is all just general information to help put SISSA and Stefano Liberati on the map. Worth knowing about if you follow "beyond the standard" physics.

 

[junglebeast]

I believe the alcubierre drive concept has an even more fundamental problem. Matter travels through spacetime, so when a bubble of spacetime moves, by compressing spacetime in front, this really only brings you closer to the target on a non-geodesic path traveling outside the manifold of spacetime. For an object embedded within spacetime, it would be the exact same distance..