I've been watching a lot of old TV on Netflix lately and thought I'd post some reviews. If Marcel can review old movies
, I can review old TV.
is a series from 2002. I never saw it when new but I had heard a lot about it from other SF fans and now I know why --it was a tremendous series. If there were any justice in the universe, this show would still be running. The casting was perfect, the acting was excellent, the stories were great and it was hilarious as well as dramatic. The plots were credible, tight and fairly original. The motivations of the characters were plausible for the given characters and villains were interesting and entertaining.
The science was a little strained and implausible. Supposedly all of humanity migrated to another solar system and terraformed a bunch of planets and moons. Terraforming was so easy that they overdid it and ended up with a bunch of sparsely-inhabited planets. Yet with the tremendous levels of technology that required, many of the planets can't afford even 20th-century technology and they are riding around on horses. Then there is the problem that the "outer" planets aren't any colder than the "inner planets" and that whenever they want to go to another planet it is only a few hours away. It all adds up to the need for a competent technical consultant.
But overall, this is one of my favorite TV series ever. If you get Netflix, I'd recommend adding the two seasons of Firefly to your "instant queue" first thing.
is an SF series from 1993. You can really see the age of the film in the way that they handle technology. For example, station personnel have small personal communicators, but most people --even VIPs-- do not have anything like a mobile phone. The plots are pretty good except that there is a tendency for supposedly smart and experienced military people to make ridiculous security mistakes. At least these mistakes are only used to heighten the suspense and not to create artificial plot points. In other words, they do stupid things, but usually nothing bad happens because of it.
My biggest complaint is that all of the main characters come off as self-indulgent drama queens. For example, a group of people who are supposed to be experienced leaders and military people are on a very time-critical mission to save the galaxy from being destroyed. One of them disappears from the ship. They have no idea how to get him back or even if it is possible to get him back, but there is still a huge amount of drama over whether they can bear to complete the mission after the loss or will abandon the universe to total annihilation while they stop and grieve. When they decide to go on with the mission it is played up like a great act of courage, sacrifice and dedication that they aren't going to let everything they have ever known be destroyed by sentimentality.
Despite the hyperdrama, the show is still entertaining and I'd recommend adding it to your instant queue, but not among the first selections.
mechanics, thermodynamics, and gravity
Apparently there is a new physical theory that gravity arises out of entropy
(link from instapundit
A few month's ago, Erik Verlinde at the the University of Amsterdam put forward one such idea which has taken the world of physics by storm. Verlinde suggested that gravity is merely a manifestation of entropy in the Universe. His idea is based on the second law of thermodynamics, that entropy always increases over time. It suggests that differences in entropy between parts of the Universe generates a force that redistributes matter in a way that maximises entropy. This is the force we call gravity.
This is interesting because I've always thought physics should concentrate more on thermodynamic-style theories rather than mechanical-style theories, and up to now mechanical-style theories have been far more dominant.
Consider a box divided into two
chambers, A and B. Chamber A has high-pressure air and chamber B is a
vacuum. You can extract useful work from this system by putting a fan
between the two chambers and allowing air to run through the fan from
chamber A to B. The moving air turns the fan and you can use a belt
attached to the fan to turn something else. This system does work.
I'm going to be a bit coy about how “work” is defined
here, but think of it as doing something like running a car or
generating electricity or cooling a house.
This two-chamber system will do work
until the pressure in the two chambers is equalized. After that,
there is no longer any organized motion of air from one chamber to
another to turn the fan (there may be random microscopic motions of
air, but these cannot be used to perform work). As the two chambers
become more equal in pressure the system loses some of its potential
to do work.
There are many other examples of
two-chamber setups that can do work. For example, you can have a
chamber with hot water in one side and cold water in the other. You
can put a heat engine between the two sides and extract energy from
it until the temperature of the two sides is the same. You can also
get work from a system where there is fresh water on one side and
salt water in the other. It will do work until the salinity
equalizes. You can get work from a system having one side full of
oxygen and the other full of nitrogen at the same temperature and
pressure. You can extract work until the two sides have the same
Now the reason that you can extract
work from these systems is that in each case, there is some sort of
force or tendency that tries to change the state of the two chambers
until the two chambers are the same, are uniform. We call this
tendency potential energy. By controlling the tendency of the two
chambers to become uniform, we release potential energy and get work.
Entropy is sort of the opposite of
potential energy. Entropy is at a minimum at the beginning when the
two chambers have the greatest difference. This is also when
potential energy is at a maximum. Once the two chambers are uniform,
the entropy is at a maximum and the potential energy is zero.
The systems I've talked about up to now
are classical thermodynamic systems. Now lets think about a different
kind of system, what would be considered a classical mechanical
system. Consider a two-chamber system of astronomical proportions.
There is an entire planet sitting in chamber A and a chunk of space
rock sitting in chamber B. The rock will want to fall towards the
planet and you can extract work from the falling rock.
Classical mechanics is about masses and
forces and acceleration. Classical thermodynamics is about heat and
energy. You can talk about masses and forces in thermodynamic system
by bringing in a very complex theory called statistical mechanics. Or
you can go the other way and use the notions of heat and energy to
talk about mechanical systems. In this way of talking, we don't talk
about the force of gravity, instead we talk about the potential
energy that exists between the rock and the planet. This potential
energy can be extracted as work, much like the potential energy of
the other systems can be extracted as work. Once the rock is sitting
on the planet, there is no potential energy left.
Throughout most of modern physics,
there has been a strong preference for the mechanical type of theory
over the thermodynamic type of theory. This is because there has been
a strong tendency to view mechanical-type theories as being
explanatory while thermodynamic-type theories were merely
descriptive. For example, in the two-chamber experiment with high
pressure air in one chamber and a vacuum in the other chamber,
physicists have felt that what is really
happening, the real
explanation goes something like this: the chamber with high
pressure has a lot of gas molecules bouncing around in it. Once you
open a hole in the wall, the molecules that are headed in the right
direction to hit that part of the wall will now pass through and hit
the fan blades instead. Each molecule that hits the fan blade will
bounce off of the blade, imparting a tiny bit of momentum. The sum of
all of those molecule-sized momentum changes add up to enough to
cause the fan to turn.
This is plausible as an explanation,
but now consider applying the same idea to the planet/rock example.
By similar reasoning we might say that the reason
rock falls is because there is a gravitational force between the rock
and the planet and that potential energy is just a mathematical
fiction. Is that plausible? Why not say that the potential energy is
real and the force is just a mathematical fiction? What makes one of
these descriptions more real, more explanatory than the other?
Frankly, I don't think that there is any rational basis to choose.
Both force and potential energy are theoretical entities, as are
molecules and momentum changes.
Now, as I said above, potential energy
is sort of the opposite of entropy, so when you apply the
thermodynamic theories to the mechanical system, it amounts to the
statement that the planet/rock system has low entropy when the planet
and rock are distant, and that once the rock is resting on the planet
the system has maximum entropy. This notion seems to be incompatible
with the statistical notion of entropy.
Recall from my original examples with
thermodynamics that high entropy is always associated with uniformity
–a state where the contents of both chambers have the same
uniform contents. This has led physicists to associate entropy with
just this state. They say that entropy is equivalent to
disorganization and by their theories uniformity is equivalent to
disorganization (I know that isn't entirely intuitive, but that's how
it is defined).
Now consider the planet/rock system
again. In this system the lowest entropy was when there was matter in
both boxes. The highest entropy is when there is matter in only one
box (which contains both the planet and the rock once all of the
potential energy has been expended). This seems to contradict the
theory that identifies entropy with disorganization unless you define
disorganization as just that state of matter that has less potential
energy. In other words, you could make a definition like this: A
state S1 is more organized than a state S2 if and only if state S1
has higher potential energy than state S2
. However, if you define
it that way, then your definition is not an independent theory –it
is just a set of code words to talk about potential energy. It hasn't
added anything to our knowledge.
An independent theory of entropy (or
potential energy) in terms of disorder would let you decide how
ordered or disordered a system is before you know anything at all
about how potential energy works in that kind of system. That would
be exciting because it would show a genuine mathematical relationship
between energy and organization. I don't know if such a thing exists
or not since I never studied that area, but I find this new theory of
gravitation interesting because it seems to imply that there is a
genuinely independent definition of entropy that applies not only to
traditional thermodynamic systems, but also to mechanical systems
UPDATE: after doing some more reading, it seems that I had the basic idea wrong. This new theory is about microscopic events, statistical mechanics, rather than macroscopic thermodynamics.