Outside of special relativity, having particles travelling faster than the background speed of light doesn't necessarily introduce causality violations, if the local /velocity/ of light, at that location and moment, in that same direction, is even greater.

Consider the case of a drifting particle falling into a black hole from null infinity. The inward velocity of the particle would be expected to hit v=c at the event horizon, and to continue increasing (unobserved) as the particle continued to fall, to an arbitrarily high multiple of background lightspeed. But the particle doesn't illegally time-reverse, because it never overtakes its own signals (which are falling inwards even faster). So gravitational event horizons provide an example of predicted (censored) super-fast motion, without involving exotica like negative energy-densities. Like Newcomb's old argument against heavier-than-air people-carrying craft, general disproofs of superfast motion are mathematically tidy, but not necessarily physically reliable.

Outside of black hole problems, super-fast motion can be legal if you use a relativistic acoustic metric instead of the Minkowski metric (in an r.a.m., the motion of a particle is associated with a local offset in nearby light-velocities, allowing the particle to move faster than background c without ever exceeding local c).

Relativistic acoustic metrics are fun, and seem to reconcile quantum mechanics with several key aspects of general relativity - they're tentatively used by some people exploring "quantum gravity" options, when modelling Hawking radiation.
... The reason why we don't use relativistic acoustic metrics seems to be partly historical/social: Special relativity got there first and established the Minkowski metric as a standard, and some relationships come out differently with an r.a.m. than they do with special relativity, so we tend to say that unless someone has convincing evidence that says otherwise, the SR version of events is considered to be "canon". And it's difficult for evidence to be considered convincing if it runs counter to one of the best-known scientific theories, so there's a kind of positive-feedback loop in operation.

Mainstream relativity guys tend not to study r.a.m.'s, not because anyone's come up with a logical reason why they shouldn't work, but because they're told that SR-compliance is mandatory for any credible relativistic field theory, and it's generally thought that violations of SR (like particles moving faster than background c) simply don't happen. So other than the quantum gravity guys, almost nobody's been looking at this class of relativity theory, and the QG guys tend to stop at the point where the thing starts to diverge from special relativity.

Short Answer: Yes, if this thing is right, it probably involves rewriting the physics rulebook, and probably junking special relativity, but ... no, the requirement for special relativity was never really as strong as many people seemed to believe. Yes, losing special relativity would be major from a theoretical and social point of view, but no, it's not too difficult to construct a relativistic alternative, if you're prepared to lose the simplifying assumption of flat spacetime.

(So yes, it might simply be a duff experiment. But it's not yet safe or sensible to assume that that's the case).

Have a Cool Day,
Eric 0955706831

31/5 -inch desktop PC harddrives are mounted with screws that are pre-metric. Newer laptop-size (" 2.5" ") harddrives have mounting screws that are metric (3 mm, I think).

There was also a nice piece on the subject in the Journal of the Franklin Institute. Apparently the US officially went metric by Act of Congress way back in 18-something, but the individual States were a little slow in ratifying and implementing it. :)

Some of the older systems also embedded a "baker's dozen" of 13 rather than the more common modern dozen of 12 (eg they used thirteen inches to the foot, and 39 inches to the yard).

Yeah, and before one publishes a paper quoting rainfall in gallons per square yard, they have to decide whether they'll be using the Imperial gallons or US gallons, because the two are significantly different. Apparently the Imperial gallon was 4.54609 litres, and the US gallon is 3.785411784 litres, making the US gallon very close to 5/6 of the Imperial measure with the same name. If someone doesn't realise that there's no single internationally-agreed definition of a "gallon" -- it's not an international unit -- then if they're unlucky, their calculations can be off by 20%

Actually, the Imperial hundredweight is 112lb, but the US hundredweight is 100lb. That's why there's a different number of pounds to the US ton and the Imperial ton, and why commodity traders talk about "long tons" and "short tons". The metric tonne is conveniently in middle. And talking of commodities, the US gallon is different to the Imperial gallon, and the US oil barrel //I think// corresponds to the eel-barrel rather than the wine-barrel? The trouble with these "natural" measures that everybody supposedly understands is that they were different all over the world. Imperial and American inches were different sizes before they both got standardised on 2.54 millimetres, and this made US and Imperial feet and miles slightly different, too. It was a nightmare for engineering work if you bought in a load of foreign machine tools and they were marked up in the wrong sort of inches. Even basic cookery measurements are locally different: a cup of sugar in the US is different to a cup of sugar in the UK. And don't get me started on pounds and ounces ... an ounce was a different weight depending on whether you were measuring liquid, grain, solid, wine, spirits, gold ... and as for feet, there might have been, what, ten different local definitions of a foot, with some using twelve inches and some using thirteen? Before the metric system, international weights and measures were a disaster. After it was introduced, people could at least define their local measures in terms of a single universally understood reference, rather than have a bookshelf of arbitrary and approximate third-party conversion tables and almanacs comparing different quantities with the same names using different materials in different countries. And often these conversions weren't officially sanctioned by anyone, because there simply wasn't an official conversion factor for the same nominal unit in Country X and Country Y. We could say that the Imperial and US inches seemed to be different by a factor of ... something ... but the US inch wasn't going to be //officially// defined as X Imperial inches, and vice versa, so the conversions were always measured approximations rather than strict engineering definitions.

To be fair, the Government guys managed to remove the first nine pounds of explosives by hand before they gave up and threw in the towel. Apparently the place is so packed with explosives-related equipment (half-built fragmentation grenades and the like) that they felt that taking anything else out would be too dangerous. Robots aren't an answer if you're dealing with a junkyard of explosive gear stacked high, where a robot fumble is liable to knock things over. Sure, if the robot gets blown up, nobody's dead ... but it could blow up the whole remaining stash. Which means that all the expensive protection work they're doing now to try to protect the surrounding neighbourhood would have to be done anyway.

Hey, don't diss thermite! For genuinely nasty explosive chemicals, try hydrazine.

When I was a kid, my chemistry book warned that hydrazine had a tendency to explode unexpectedly in response to vibration. Or heat. Or light. Or cold. Or sound. Or electrical charge. Or chemical reaction with contaminants on the surface of the holding vessel. Or roughness on the surface of the holding vessel.

Or ... basically, if you looked at it kinda funny.

And on top of all that, it's supposed to be horribly toxic.

Some explosives can become more unstable with time. Depending on the range of materials he was playing with, the fact that he might have safely put something away in a box ten years earlier wouldn't necessarily mean that it'd be safe to attempt to move that box now.

So are we allowed to shout "Bear!" in a crowded cinema?