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Science questions not worth a thread I: I'm a moron!

Discussion in 'Science & Technology' started by The Imp, May 4, 2010.

  1. Leoreth

    Leoreth Knight of Time Moderator

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    What you're saying doesn't mean that our physical theories are wrong, just that they're incomplete. In physics we use models that include abstractions - even in dimensions where, say, Newtonian physics holds true (i.e. within resting reference frames), we don't calculate the behavior of every atom of an object, we consider the abstracted objects themselves. This is called an effective model. When an effective model is applicable, i.e. going to produce correct results, is usually included in its formulation. So it's not wrong in that regard: it can do everything it claims. It's just not applicable everywhere.

    In a similar vein, general relativity and quantum physics are effective models of the world we live in. On the other hand, we don't even know for sure if a universal theory or model for the entire world is even possible.

    Theories that are "wrong" in your words may be all we'll ever have.
     
  2. Blue Emu

    Blue Emu GroFAZ

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    Or, even if possible, whether it would be useful for anything.

    It might give us exact equations for solving any conceivable situation... but the equations themselves might be too complex for us to solve.
     
  3. Leoreth

    Leoreth Knight of Time Moderator

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    I guess the main drive behind it is to resolve situations Elephantium already alluded to: where both general relativity and quantum physics ought to apply, but contradict each other, i.e. quantum gravitation. The most interesting case there is probably the very early universe that had only a quantum scale size.

    Another point is definitely the popular notion that different models for different situations seems to be an artificial approach chosen out of necessity, that can be circumvented if one looks "deeper". There isn't really anything that says this must be the case. After all, the idea of using models itself is an artificial approach chosen out of necessity.
     
  4. uppi

    uppi Chieftain

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    Oh, we're well beyond that point already. In quantum mechanics, for example, we will never be able to solve a 200 particle system exactly (on a classical computer). We will always need to go for simplifications and effective theories for larger systems.

    A more general theory will most likely have to be more complex, as it has to replicate the behavior of quantum mechanics, that we see. So finding a universal theory and then calculating everything with it is never going to happen.
     
  5. Narz

    Narz keeping it real

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    Thanks contre, Yeekim. I've read about those Soviet foxes before. The article on wiki on neoteny was interesting too (though it sounds like a hard concept to measure as it's somewhat subjective). I feel a little neotenous (word?) myself, in spirit anyway, not in looks & it's nice to know it's mostly a positive & correlated with intelligence (generally).
     
  6. Blue Emu

    Blue Emu GroFAZ

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    Stupid question:

    What acceleration (in g's) is required in order to accelerate from zero to 2,000 kilometers per second within 200 meters?
     
  7. Narnia

    Narnia Chieftain

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    Assuming that acceleration is constant, the formula you need is:
    v_f^2=v_i^2+2a∆d
    Also, we need to convert km to m, so 2,000km/s becomes 2,000,000m/s
    therefore:

    ((2*〖10〗^6 )*m/s)^2=(0m/s)^2+2*a*200m
    4*〖10〗^12*m^2/s^2 =a*4*〖10〗^2*m
    (4*〖10〗^12*m^2/s^2 )/(4*〖10〗^2*m)=a
    1*〖10〗^10*m/s^2 =a
    a=〖10〗^10*m/s^2
    a=〖10〗^7*km/s^2
    a=10,000,000*km/s^2

    Gravity is ~9.8m/s^2. For simplicity's sake, 10m/s. I think that this means that it is about 10^9 times the strength of gravity. (that's a 1 with 9 zeros after it)
    Btw, this figure seems a little high, I may have made a mistake. However, I'm not used to working with high figures so...
     
  8. sanabas

    sanabas Psycho Bunny Hall of Fame Staff

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    No mistake, it is 1 billion g.
     
  9. peter grimes

    peter grimes ... Moderator

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    As apes go, we are definitely neotenous.

    Dawkins has a wonderful chapter on Neoteny in Ancestor's Tale. As he says, once you know what to look for you start seeing it all over the place.

    EDIT: just tracked it down - it's the Axolotl's Tale. I really can't recommend this book enough. I've read it 4 or 5 times now, and it's always still informative. It might be my favorite book on evolution.
     
  10. emzie

    emzie wicked witch of the North

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    It really is an awesome book.
     
  11. Narz

    Narz keeping it real

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    I'll check it out, I find evolution & it's implications fascinating. :)
     
  12. Phrossack

    Phrossack Armored Fish and Armored Men

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    Sorry to sound stupid, but suppose you have a magnetic piece of metal. Then you melt said piece down and pour it into a mold. Will it still be magnetic when hardened (I'm pretty sure it wouldn't)? If not, would it be possible to re-magnetize it?
     
  13. madviking

    madviking north american scum

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    Magnetism is about the electric dipoles lining up. So when you melt something the dipoles get scrambled, making the material lose magnetism.

    If you wanted to remagnitize it, it depends on the material. For iron, I think if you let it cool in an external magnetic field you'll get it back to magnetic.
     
  14. uppi

    uppi Chieftain

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    There is a temperature above which the metal loses its magnetization. This is called the Cuire temperature. For all ferromagnetic metals, this is below the melting temperature, so for all metals the melt is not (ferro-)magnetic anymore.

    If you then slowly cool down the metal to a temperature lower than the Curie temperature and apply an homogeneous external magnetic field (the magnetic field of the earth can suffice), it will become magnetized again.

    edit:
    No, it is about the magnetic dipoles lining up
     
  15. Narnia

    Narnia Chieftain

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    Speaking of magnetism, can you make a permanent magnet with an electromagnet?
     
  16. uppi

    uppi Chieftain

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    Yes, you can use an electromagnet to magnetize a ferromagnetic material so that it becomes a permanent magnet.
     
  17. emzie

    emzie wicked witch of the North

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    What would happen if a hypervelocity star smacked into another star? Ignore that such an event would be exceedingly rare :)
     
  18. Quackers

    Quackers The Frog

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    I got a hypothetical.

    Me and Uppi are in deep space far away from any strong gravitiational pull and we are alive in our space suits. Suddenly I get an urge to kill Uppi, so in my murderous rage I push Uppi with all my strength. What the hell happens?
     
  19. peter grimes

    peter grimes ... Moderator

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    you move away from the point of contact with speeds proportionate to your masses. If you are both 75kg then you'll both have equal both opposite velocity
     
  20. Quackers

    Quackers The Frog

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    Does the velocity last forever or untill we reach some gravity?
     

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