Very good but
you should really acknowledge that the quote is from Hitchhikers
2677 publicly visible posts • joined 24 Mar 2010
but space is BIG, VERY BIG.
Consider if there were 1 million advanced civilizations in the galaxy willing to send probes - they've got a choice of ~4e11 stars to send a probe to. OK they could rule out quite a lot but it's still one very large number of which we are 1. Plus the distance. So we'd be dependant on a civilization developing in our neighbourhood, wanting to send missions, choosing us amongst many, and the probe arriving, not malfunctioning and us spotting it.
Far fetched
It's going to need some mechanism to steer it just to keep to the earth's curvature unless the ballistic arc just happens to match.
OK if it hits something solid like a building or tank but a thin-walled, unarmoured warship - it will punch a hole clean through unless it hits something with significant resistance/mass.
I think you need to check your figures - at ~9 kW I make it 111 cars/MW - I think you might have divided by the six hour charge time which isn't relevant.
The power they require is ~1MW for 111 cars. The energy consumption is ~1MW.h for 19 cars if the charge time is 6 hrs
Well on my OpenSuse installations neither Firefox or Thunderbird will allow executables to run by just clicking and even if you save the file it's set as non-executable so you really have to have a death wish to run an unknown binary. It doesn't matter at all what the extension is.
It is possible to have FF etc set to run interpreted files if you really, really want to.
Correct if that's the speed of sound in whatever medium.
That answers both questions.
(should be easy enough try with string - not sure about the neutron star rod)
"What if I pulled on the string at faster than the speed of sound in the string?" - I think you might snap the string.
Common sense or "gut feeling" is not always a good guide to reality. To some extent that's why we need mathematics. Try reading about chaos theory which doesn't deal with the very small like QM or the very fast/large like relativity but still provides some really weird and wonderful effects in the everyday world.
Depends on how much you are buying but ~£4/L - this stuff is used all the time with superconducting magnets. Chemistry NMR instruments hold ~~ 100L
Incidently the LHC uses ~120000 kg or ~~ 650000L I believe.
On another point (although I wouldn't recommend trying this) a stream of liquid nitrogen droplets will bounce readily off the skin without harm due to the boiling liquid being insulated by a layer of gas. As the skin cools however then the problems start. We used to use these types of materials without gloves as any finding its way down a glove could easily produce a nasty burn.