Recent content by LTP

  1. L

    Find (a,b) for a system of linear equations given

    Ok, so I found that (a^2+a)x_4 = ab+b (ignore #3, I made a miscalculation). a^2+a = 0 => a=0 or a=-1 No solution: a^2+a=0 and ab+b != 0 a=0, b \in R except 0 One solution: ab+b != 0 <=> ab != -b a \in R except -1 and b \in R or the opposite. No unique solution: a^2+a=0 and ab+b = 0 a=0 and...
  2. L

    Find (a,b) for a system of linear equations given

    No, the picture just shows the system of equations. This is it: http://peecee.dk/uploads/042009/Screenshot-1.png Should I reduce it even further to the "reduced row echelon form", if I want to use your suggestion?
  3. L

    Find (a,b) for a system of linear equations given

    http://peecee.dk/uploads/042009/Screenshot4.png I have to find (a,b) \in R when the system of linear equations a) have no solution b) have one solution c) have infinitely mane solutions. I've converted the equations so they're on a row echelon form. My question is, what do I do from here?
  4. L

    Time and the 2nd law of thermodynamics

    There are a lot of different formulations of the 2LT (2nd law of thermodynamics). I think the arrow of time is derived from the macroscopic, phenomenological 2LT: "In an isolated system, the entropy has a tendency to increase." The "has a tendency"-part accounts for fluctuations. I think this...
  5. L

    Time and the 2nd law of thermodynamics

    Time, or rather the arrow of time, is defined within the 2nd law of thermodynamics: The future is in a higher entropy state than the present, which in turn is in a higher entopy state than the past. But when the universe, our isolated system, reaches the maximum entropy state - heat death -...
  6. L

    Is the Cosmological Arrow of Time Linked to the Thermodynamic Arrow of Time?

    Is the cosmological arrow of time just a special case of the thermodynamic arrow of time, where the universe is the isolated system?
  7. L

    Karl Popper on brownian motion and the 2. law of thermodynamics

    I'm reading an old, maybe outdated, paper by Karl Popper about the 2. law of thermodynamics, brownian motion and perpetual motion. Popper writes: Before that, Popper has described Planck's law as: So, my question is: Is brownian motion considered to be a violation to the 2. law of...
  8. L

    Reversibility and Carnot cycle

    I have two short questions: 1) Is the Carnot cycle completely reversible? 2) \Delta S = 0 for a reversible process, right?
  9. L

    Diffraction effects and wavelengths

    Just in general; is there any diffraction effects for light coming from a normal light bulb? What about Young's double-slit experiment?
  10. L

    Entropy and information: Do physicists still believe so?

    I agree. Really? - How? AFAIK "normal" computers don't come anywhere near that lower limit. More likely 40 years, Landauer published his paper in 1961, Bennett published his solution to MS in the same decade.
  11. L

    Entropy and information: Do physicists still believe so?

    But also in "classical" entropy? So what is preventing us from being such a demon? Do you imply that the act of information acquisition increases the entropy?
  12. L

    Diffraction effects and wavelengths

    Do higher wavelength radiation have more pronounced diffraction effects than low wavelength radiation, and why is that?
  13. L

    Entropy and information: Do physicists still believe so?

    The entropy of a system is S = k*ln W If we obtain some information about the microstates, e.g. know the location and velocities of some of the molecules, then W is decreased by a amount w, so S1 = k*ln(W-w) That is an decrease in entropy, i.e. S1 < S. Do physicists still "believe" so?
  14. L

    Does Removing a Partition Increase Entropy in a Gas Box?

    That is way over my knowledge of the subject, but I may have to look into it. Thanks anyway. Thanks for the search term, I was not aware that I had already been adressed by Gibbs.
  15. L

    Does Removing a Partition Increase Entropy in a Gas Box?

    Yes, the two side are at the same T. They are perfectly symmetrical. The real problem is when the two gases in each side is of two different kinds. In that case, there is an entropy increase. Do I need elaborate #3 a bit more?
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