The Second Law Is...

I will sometimes see science blog posts refer to "The Second Law" as if we all knew exactly what they meant.

As far as I can tell, "The Second Law" could refer to any of:

  • F = ma
  • A line joining the planet to the Sun sweeps out equal areas in equal times
  • ΔS≥0
  • A robot must obey any orders given to it by human beings, except where such orders would conflict with the First Law.
  • The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

(And probably a number of other things.)

10 responses so far

  • Naved says:

    Somewhat off-topic, I've always wondered why Newton's Second Law (F=ma) is not his First Law. There is nothing the first law says that is not part of the second law. So really, Newton has two laws - F=ma and the action/reaction law.

  • Bau Ur says:

    or could be
    "You shall not make for yourself any graven image, or any likeness of anything that is in heaven above" which means you are in big trouble for those cool Hubble tee shirts you gave us.

    But I think it's probably the robots one.

  • rknop says:

    Naved -- this is very true. But for some nutty reason, people seem to like things in sets of three. (Maybe it's because all of these things came out of a culture heavily influenced by Christianity? Dunno.)

    Re: Kepler's laws, I never remember which is which. I always think P^3=A^2 is the Second Law, because I was programmed by Newton to think that the Second Law is where you find the handy equation.

    Bau: d'oh!

  • Thony C. says:

    that the population should remain in ignorance of the results of the application of psychohistorical analyses

  • Mary says:

    Surely the second law is "In a closed system, entropy must increase." That's the one with all of the troubling philosophical implications, after all...

  • (Gordon) Moore's Law is the observation that "the number of transistors that can be placed inexpensively on an integrated circuit has doubled approximately every two years." There's also Moore's Second Law: "The capital cost of a semiconductor fab [factory] also increases exponentially over time."

    (Theodore) Sturgeon's Second Law: "Ninety percent of everything is crud."

    Mendel's Second Law (the law of independent assortment): "During gamete formation the segregation of the alleles of one allelic pair is independent of the segregation of the alleles of another allelic pair."

    Poor Robert Hooke never got a second law named after him.

    Homework: Fick's Second Law and Paré's law (the second law of toxicology)

  • Raskolnikov says:

    Second Law of Raskolnikov: Read the First Law first, cheater!

  • Zuska says:

    I just want the robot. Send it to my house, now, because the house needs cleaning.

    In all those futuristic robot stories, the robots end up weaponized and are made over in human likeness as love objects and child replicas. I think if more women were writing the stories, the stories would be very boring, because they'd go something like this: "Hey, I just designed this awesome robot. It will clean freaking everything! And cook a nice meal too." "oh, that's great! Let's meet for drinks later!" "Okay, great!" The end.

    Sorry, this is slightly off topic. What were we talking about? Oh right, second law. Well, if you take my house as a closed system...

  • The Giant says:

    I always thought the second law as "When all else fails read the directions".

  • drugmonkey says:

    I think PalMD's second law is "the Internet is 10% bad medical advice". Or perhaps it is "The internet is 90% porn". I keep getting the order mixed up....