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pzkpfw

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Everything posted by pzkpfw

  1. Does Brontosaurus live on Pluto?
  2. 4. Which is one less than the number of posts you made in this thread since writing "I won't post anymore".
  3. There's a difference between "self taught" and "untaught, and making stuff up". I'd suggest starting by learning what current science thinks, and why, and go from there.
  4. Yeah, I figured as much by noting your previous thread: http://www.scienceforums.net/topic/78958-does-this-hold-true-for-all-prime-products/#entry769264 Again, what's the largest value you've tested against?
  5. Isn't the point of RSA, not that it can't be done, but that with big enough p and q it'll just take too long to be feasible? What's the largest value you've tested against?
  6. The momentum isn't conserved, because of that friction. The energy of the spinning gets changed into heat and sound.
  7. Do you think dark matter is some kind of fixed background on which the rest of space sits?
  8. Lexx, episode 1.3 explains it all.
  9. Earthquakes are caused by overuse of bold text in forum posts. It causes an imbalance.
  10. Well, er, yeah, 8 bit bytes is pretty much by definition. What I was referring to is that the thing being addressed (by a given op code, in a given addressing mode) might not be bytes, it might be words, of whatever word size the particular CPU uses. And adding to his confusion over signed offsets with wrap around makes it simpler? As Sensei belaboured, it'd seldom work the way you described.
  11. ( Assuming an addressing mode where the offset has the same magnitude as the the base address. Not always the case. )
  12. Imagine a bit of machine code that needs to jump to a different address. The equivalent of "if x = y then go to subroutine five". If the address offset jumped to could only be positive, you'd have a program that could only go forward. You'd never be able to do loops and such. (Unless you used all absolute addresses and "hard coded" the destination of jumps backwards). The Z80, for example had a relative jump that allowed an 8 bit (1 byte) address offset. That amounted to a jump of 128 bytes forwards or 127 backwards; not just 256 bytes forwards. (Note that the Z80 had a 16 bit address bus, so 8 bit offsets did not cover the full address range, from any given location). Sorry, but you tend to be very sloppy with terminology. (Not that I'm claiming infallibility). It's not 2^16 bits, it's 16 bits. (In this example). That doesn't "store" 65536 addresses, a 16 bit value can hold a number (assuming simple unsigned integer, e.g. not BCD or something) from 0 to 2^16 - 1, or 0 to 65535. That might be used to point to an address, i.e. 65536 different locations. What's at those locations might or might not be a byte - it depends on the CPU architecture. For relative or offset addressing, we need to be able to look forwards or backwards from a given location, so as a signed value, those 16 bits allows a range approximately + or - 32767. Essentially (approx) half of the 65536 forwards, half of it backwards.
  13. So again, the lack of evidence is somehow evidence.
  14. Wouldn't you be better off directly harnessing the water? (As is already done).
  15. People have had hearts replaced by machines; not just having machines pump their blood temporarily during an operation, but permanent replacement. It's still a new science, and the success has been varied. But still, it would have been very obvious very quickly if the ability of the recipient to think had changed significantly. And what about heart transplants? Has any recipient of another persons heart woken up from surgery and asked "what am I doing in this body?"? This stuff is garbage.
  16. Strange is right, that there isn't enough information there; but since I can see what you're trying to do with that, I'll just go ahead and (simplify, and) say "no". The thing is, if you're going to reject the shell theorem because it's an approximation, you can't just substitute that with another approximation. If you're going to insist on ignoring the shell theorem, you need to do something like actually calculate the effects of the individual stars outside the orbit of S2, not just talk your way into a claim that supports your idea. Go ahead.
  17. It's true the setup isn't very clear about whether the train is still accelerating or not at the time the flashes occur, but that's not really what I was commenting about in your post. You just seemed to be implying an observer outside the train as having a "special" or "absolute" rest frame. Since they were at rest with the train and clocks at the start, I can see that's why you'd see them as "having" the frame within which the clocks are "still synchronised" (and I can't say I disagree (so my post #14 may be backward)); but that wasn't clear in your post.
  18. That's from the point of view of an outside observer, which is no better opinion than that of an observer on the train who (while it isn't accelerating) is entitled to consider themselves as at rest. The relativity of simulatenity doesn't say one special observer can consider events to be simultaneous and others can't, it says events simultaneous for one observer won't be simultaneous for an observer moving in relation to that observer. (Or vice versa).
  19. David, imagine you are floating in space with a mass in front, and another five equal masses the same distances behind, left, right, above and below you. That is, you are exactly in the middle of these six equal masses. Clearly all their effects will cancel out. e.g. The mass in front "pulls you" forwards, but the mass behind "pulls you" equally backwards. Now, using rockets move yourself towards the front mass, and then reverse to stop. You might think that now you are closer to the front mass (and further from the rear mass), it's "force" would be stronger and you'd be pulled towards it - that you'd begin to drift forwards. But that doesn't happen; because the masses that were left, right, above and below you are now also a bit behind you. Their "force" in the rearwards direction adds to that of the "force" from the rear mass. Newton, who could do calculus, figured out (proved mathematically) that inside a shell of equal density, these "forces" all cancel each other out. e.g. if Earth was a thin shell of ultra dense material, so that it's surface gravity was exactly the same as it is now, but it was hollow - you could be anywhere inside that shell and you'd feel no "force" of gravity in any direction. That's the Shell Theorem. And it's why, as we can treat the Galaxy as homogenous (all the stars more or less evenly spread), S2 can pretty much ignore the stars further out than it. It's the masses (such as the black hole) inside its orbit that matter most.
  20. I would expect (but am very happy to be shown wrong) that the end clocks would remain synchronised in the frame of the train, as they're both experiencing the same acceleration on that train. So they'd both fire at their pre arranged time, with the flashes reaching the centre clock at the same time, and that clock does stop as expected. The outside observer, considering themselves as at rest and the train moving, would also see that centre clock stop (it can't both stop and not stop). From their point of view that clock was moving towards the light from the front clock and away from the light from the rear clock, so for the flashes to have reached that clock at the same time, the rear clock must have (considered in the frame of the outside observer) flashed before the front clock. Well, that's the relativity of simultaneity, as Einstein showed, observers in relative motion can't agree on whether events happen at "the same time". The only paradox is if one demands that simultaneity must be the same for all observers, which creates a centre clock stops and doesn't stop situation. But that's getting it all upside down.
  21. Can a sacrificial metal be used to protect the electrodes?
  22. See: http://en.wikipedia.org/wiki/Lunar_meteorite (A form of communication, very slow (compared to light), telling us about our Moon).
  23. That's the standard idea. There's one cat (in my back yard). It changes position, e.g. BBQ table to birdbath. It also changes time, e.g. it was somewhere at 1 p.m. and it was somewhere at 2 p.m. If it was very lazy, it might stay in the same position, but be there at those two times. Who says that? We all change coordinates in time. I woke up at 6:30 a.m. this morning, now here I am at my PC at 7:23 a.m. My position in time and space has changed. I do note your earlier comment on the size of the cat (30 cm). Position (and physical extent) is measured in 3 dimensions, so the cat (an assembly of atoms, and what they're made of) has extent in height, width and depth. But time has a single dimension, so there's no equivalent "time extent" for the cat. It's somewhere at some time. A nanosecond later, that one cat may be in the "same" place (depending on what measured against) or it might have moved. Its space and time coordinates can have changed. But it's still one cat.
  24. If I look out my window at 1 p.m. and see my cat on the BBQ table, then I look out again at 2 p.m. and see it on the bird bath, that simply means it's location (time and space has changed). It doesn't imply there's a bunch of other cats outside that I just haven't seen. (And any cat so far away that light from it hasn't reached me "yet", will have had no other effect on me.)
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