p1t1o

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  1. I second what @steve_v said. If you are unsure of what is causing the problem, salvage as much data as poss, format and reset to factory. Reinstalling windows is a pain in the B, but its less of a pain than trawling through your entire harddisk multiple times with various software tools that may not work, may make things worse, and will just generally take ages because of said lag. I think MalwareBytes is pretty good, if it doesnt find anything, best to go for the nuclear reformat option. When recovering your salvaged data, scan it for suspect stuff, naturally. However, I wouldn't rule out a hardware failure of some kind, do you get any beeps from the motherboard on startup? Vaguely plausible culprits are a burned out RAM unit or a harddisk close to failure - could explain the lag that comes without anything noticable in TaskManager. How old is your harddisk?
  2. Its probably almost as impossible, but how would things change if the mission remit was manned, but without landing the astronauts on the martian surface?
  3. That does give a good description of cavitation, but - and I am at risk of suffering from an over-inflated ego here, for sure - it doesnt explain how a slower, non-cavitating ship would produce a frothy wake. Everything about cavitation says the bubbles collapse rather rapidly, even the included explanation of cavitation damage supports that. And you can see in images of ships, frothy foam is generated at the bow as well, thats not cavitation. Theres plenty I dont know about the subject though. "These cavitation bubbles have effects in addition to forming a bubble trail behind the ship. First of all, each mini implosion makes a loud noise." These two sentences seem incompatible with each other?
  4. Oh of course, I think those special propellers are quite niche. I just mentioned it for completeness/interest.
  5. I would have a hard time believing that the paperwork could be done in 3 years, let alone anything else. I work in international regulatory affairs for the chemical industry and I am completely serious. Yes, its possible in a "going faster than light is impossible" kind of way, but so is a lot of things. Like converting the Moon into a ring system for Earth.
  6. I do know that some propellers for high-speed applications are specifically designed to operate whilst cavitating, whilst others are designed to operate only half-submerged, to obtain the same effect by entraining atmospheric air. https://en.wikipedia.org/wiki/Supercavitating_propeller
  7. ho-HO! I see what you did there SCIENCE JOKE!!
  8. The density re-asserts itself quite readily though, hence the froth is on the surface where you can see it. If a large volume of water had its density lowered drastically for any length of time, it would float to the surface and spread out across it like an oil slick, which you can see, it kinda does. Bubbles caused by cavitation - I recently said they collapse rapidly. By "rapidly" I meant "whilst still in contact with, or very near to, the surface causing them." - they can only exist in the regions of lowered pressure caused by the passage of the propeller blades (or whatever caused it). Occasionally, there may be some slightly longer lived areas of lowered pressure in vortices and the like, where some bubbles may last for a few seconds, but it wont be a great volume. The frothing you see is caused by air entrained from the atmosphere by a turbulent surface, the propellers, and possibly effects caused by the passage of the vessel.
  9. I shoulda said something more like "within the same order of magnitude" but hey-ho! Well what I shoulda done is actually look it up. But I was nearly right
  10. If your object were stationary relative to the sun at 1AU, it has Gravitational Potential Energy of approx 0.9GJ/kg, which would, if dropped, be all converted to kinetic energy, giving a final velocity (at zero distance, ie: at the centre-of-mass of the Sun) of around 42km/s. (Ahh! Ahh! 42! 42!) Naturally, the speed would be somewhat less upon reaching the surface of the sun, some distance from the CoM, but you get the idea. Your "push" would have to be on the order of km/s to even be noticeable upon contact with the Sun. There is no "normal" matter that would not be vaporised upon "contact" with the sun in a short space of time. Naturally "contact with the sun" is a hazy concept because being gaseous, its "edge" is ill-defined, and it gets pretty danged hot on approach as well. Gravitationally bound object like neutron stars would survive, but in that case you are throwing an object with nearly the same amount of with a mass of the same order of magnitude as the sun, which is a bit like throwing a 20-ton boulder into a pond to see what kind of splash it makes - it will make an interesting splash, but you wont be left with the same pond afterwards.
  11. Then they most likely dont survive...
  12. Very hard to seperate from politics, but Mars in 3 years? Seems like an incredibly tight schedule [to do it with a hint of a care for safety and with a realistic budget]. And thats not even taking into account the 6 month journey to get there. Unless we dont need to bring the astronauts back, in which case its probably doable. And if they dont have to be alive when they land, then its probably even trivial. *** I dont imagine the lifespan of topics with "trump" literally in the title to be very long though
  13. So it seems it strongly depends on the size and speed of the vessel, but it could happen (extreme in-and-of-itself risk of being overboard notwithstanding). Cavitation bubbles collapse rapidly, but air entrained from the surface could have a similar effect.
  14. So the common wisdom is that if you fall off a moving ship, you are in dire risk of being "sucked" under the water by the turbulence of its passing, or possibly drawn into the propellers. Does anyone know if this is true?