easier to scramble an egg than to unscramble it. Entropy is a measure
of the scrambledness of the energy, and because there are more ways
to be scrambled than to be unscrambled, the scrambledness of the energy
tends to increase. The entropy tends to go up.
is simply the nature of the underlying existence showing through
in space and time, and its amount remains constant. It is only the
quality of the energy, its usefulness, that gets degraded. And entropy
is a measure of this degradation."Die Energie der Welt
bleibt konstant; die Entropie strebt einem Maximum zu."
(The energy of the world remains constant the entropy strives to
a maximum.) -- Rudolf Clausius (1822-1888).
This is a statement of the first and second laws of thermodynamics.
And the term laws doesn't mean edicts, but ally statements about
how matter behaves. Physics is about how matter behaves, and these
are statements about that. This is simply a statement that although
the energy in the Universe remains constant, the entropy tends to
entropy is a measure of the usefulness of the energy. Gravitational
energy and the kinetic energy of large moving objects is completely
usable. Heat energy is not, because the directions of the motions
of the particles have been scrambled. That's what we call heat.
And temperature is a measure of the mean kinetic energy of the molecules.
When you panic stop on the freeway, the kinetic energy of your large
moving vehicle gets scrambled to heat by friction in the brake drums
and the brake shoes, the tire and the road. If you could unscramble
it, it would once again be the kinetic energy of your large moving
vehicle. Now if, instead of being scrambled by friction in the brakes,
the energy had been run into a flywheel (which is a large moving
object), you could have used it to restart your car. That's how
they restart the mail trucks and the milk trucks in Europe.
all living organisms must find and use a source of energy less scrambled
at the start, life is impossible except in a world that is going
from bad to worse. All living organisms live in this cascade of
increasing entropy by directing streams of the increase through
their forms. For all living organisms, negative entropy is food.
When you eat it, it's cake; when you're through with it, you push
last century, and in the early days of this century, it was usually
taken for granted that the mix of the chemical elements in the Universe
was given at the time of creation, if there was a creation, or had
been around forever, if there was a forever. (It was not known then
that the other chemical elements are fashioned from hydrogen in
the bellies of the stars.) And it was thought that if you just shuffled
the mix long enough, it might come out in the present configuration
again. But there was the problem of entropy. It was already known
that entropy tends to a maximum and would surely go up. (In those
days the expansion of the Universe had not been noted, nor its extent.)
Then, considering the consequences of the continuously increasing
entropy, it was thought that the Universe would eventually reach
a "heat death." It was thought that eventually every chemical
reaction that could have taken place would have taken place, and
that everything that could have fallen would have fallen. And it
was thought that when all these other energies had gone to heat,
the Universe would be just a little warmer and life would be muffed
turns out that, like life, the formation of galaxies and stars would
also be impossible except in this cascade of increasing entropy.
A galaxy could not be formed by stars falling together because the
stars would be too lonely to collide. The entropy would not go up
because the stars would not collide and therefore the energy of
falling would not be scrambled to heat. Galaxies are formed when
clouds of hydrogen fall together because the clouds are big enough
to collide. The clouds, unlike the stars, are large with respect
to the spaces between them. So the particles of each cloud collide
with the particles of the other cloud and thus scramble their motions
to heat. (Stars like the Sun have a density of more than a pound
per pint, whereas the density of the interstellar clouds is closer
to a pound per billion cubic miles.) It is because of their large
sizes that the clouds collide, and the energy of falling is transformed
to heat. We say that the entropy has gone up.
stars are formed when clouds of gas and dust collide because the
entropy goes up as the energy of falling is transformed to heat.
(Stars are not hot because of nuclear fusion at the core. They are
hot because the energy of falling has been transformed to heat.
The heat released by fusion simply keeps them from collapsing farther
and thus getting too hot. But it's only temporary.)
within the Universe, the entropy goes up. However, for the Universe
as a whole, the entropy may not go up. The observable Universe has
a border, some fifteen billion light years distant in all directions,
imposed on us by what is called "the expansion." It is
imposed on the observer by the fact that all the distant objects
appear to be moving away. At some fifteen billion light years from
us (at the present apparent rate of expansion), they are estimated
to be receding at the speed of light. It is this apparent"
expansion" that imposes a border to the observable Universe
because things receding faster than the speed of light are not observable.
And if the rate of expansion were increased, the border would of
course be closer.
when we consider matter near the border, its radiation, as seen
by us, would be red-shifted (lowered in frequency) much as the pitch
of the fire engine's bell is lowered where the fire engine has passed
us and is going away. But if the energy of the radiation of the
distant particles is lowered, so too is the energy of the panicles
themselves, and therefore also their mass. (We know from Einstein's
1905 equations that what we see as matter is just potential energy.
Swami Vivekananda had suggested this to Nikola Tesla some ten years
earlier. But Tesla had failed to show it.) Now there are two very
interesting consequences of this apparent lowering of the mass.
First, radiation running through a field of low-mass particles would
be so often picked up and reradiated that it would be thermalized
to 3° Kelvin and would appear as the background radiation discovered
by Penzias and Wilson in 1965. Second, if the mass of the particles
approaches zero, their momentum must also approach zero (because
the momentum is the mass times the velocity, and the velocity approaches
a constant). But if the momentum approaches zero, so does our uncertainty
in that momentum. Then, by Heisenberg's uncertainty principle, our
uncertainty in where they are must approach totality. (According
to Heisenberg's uncertainty principle, if we can know where a particle
is, we cannot know its momentum. Likewise, if we can know its momentum,
we cannot know where it is. So if we can know the momentum of a
particle at the border, we cannot know that it's at the border.
We cannot know both its momentum and its position.) Now if the particles
thus recycle by "tunneling" back into the observable Universe
as hydrogen (with its gravitational energy thus restored) then the
entropy of the whole Universe might not increase.