Group items matching

in title, tags, annotations or url

I would be very very skeptic on this results and am actually ready to take bets that they are victims of something else than "new physics" ... some measurement error e.g.

Assuming that this system is feasible, and taking the results of Chinese team (Thrust of 720 mN http://www.wired.co.uk/news/archive/2013-02/06/emdrive-and-cold-fusion), I wonder whether this would allow for some actual trajectory maneuvers (and to which degree). If so, can we simulate some possible trajectories, e.g. compare the current solutions to this one ? For example, Shawyer (original author) claims that this system would be capable of stabilizing ISS without need for refueling. Other article on the same topic: http://www.theverge.com/2014/8/1/5959637/nasa-cannae-drive-tests-have-promising-results

To be exact, the chinese reported 720mN and the americans found ~50microN. The first one I simply do not believe and the second one seems more credible, yet it has to be said that measuring such low thrust levels on a thrust-stand is very difficult and prone to measurement errors. @Krzys, the thrust level of 720mN is within the same range of other electric propulsion systems which are considered - and even used in some cases - for station keeping, also for the ISS actually (for which there are also ideas to use a high power system delivering several Newtons of thrust). Then on the idea, I do not rule out that an interaction between the EM waves and 'vacuum' could be possible, however if this would be true then this surely would be detectable in any particle accelerator as it would produce background events/noise. The energy densities involved and the conversion to thrust via some form of interaction with the vacuum surely could not provide thrusts in the range reported by the chinese, nor the americans. The laws of momentum conservation would still need to apply. Finally, 'quantum vacuum virtual plasma'.. really?

How sure is the information that a human body would not completely burn / ablate during atmospheric re-entry? I am not aware of any material ground tests in a plasma wind tunnel confirming that human tissue would survive re-entry from LEO.

Since a steak would not even be cooked by dropping it from very high altitudes (http://what-if.xkcd.com/28/) I would doubt that a space tourists body would desintegrate by atmospheric re-entry.

Funny link, however, some things are not clear enough: 1. Ablation rate is unknown 2. What are the entry conditions? The link suggests that the steak is just dropped (no initial velocity). 3. What about the ballistic coefficient? 4. How would the entry body orientation? It would be a quite non-steady state configuration I guess with heavy accelerations. 5. How would vacuum exposure impact on the water in the body/steak and what would be the consequence for ablation behaviour? 6. Does surface chemistry play a role (not ablation, but catalysis)? My conclusion: the example with the steak is a funny and not so bad exercise, not more.

Nice article, actually! It summarizes in "human readable format" why and how too many cosmologists and string theorists just went bozo...

really ! this article should go for the ignobels ! http://arxiv.org/abs/0808.3778 I wonder which substance theorists are taking... I will avoid...! but really this is very preoccupating: "complex structures will occasionally emerge from the vacuum as quantum fluctuations, at a small but nonzero rate per unit spacetime volume. An intelligent observer, like a human, could be one such structure." Is this a new alternative to Darwinism...??? a support to creationism ?? How can a physicist can write such non-sense ?

and this is published in PRD !!!