Gintis Reviews Lawrence Krauss, A Universe from Nothing:
Why There is Something Rather Than Nothing
Atria (2012)
Herbert Gintis
This book is a very engaging and highly enlightening introduction to modern cosmology, with
forays into quantum mechanics and general relativity thrown in. Indeed, I have never seen better.
Krauss's ploy to get you to read this book is to add some half-baked theology/metaphysics that
will draw in those interested in the debate as to whether science can replace faith in interpreting
our world. Krauss's argument is that modern cosmology shows that we have a universe without
the need for positing a Creator. He is not at all convincing (which no doubt motivates most of his
one-star detractors in the Amazon reviews of this book).
The story starts with the discovery that Cepheid variable stars exhibited a regular relationship
between brightness and period of variation. In 1913, the distance to a known Cepheid was
accurately measured, making it possible to use the brightness of a Cepheid in any part of the
visible universe to measure its distance. Hubble used this fact to show that there were galaxies
outside our own, and that the universe is expanding.
Another advance allowing us to measure distances in the universe was the fact that Type 1a
supernovas, which occur only once per hundred years per universe, have a tight relationship
between brightness and the length of time they shine before winking out. We can measure the
time, and then infer the distance to the galaxy containing the supernova. Because there a billions
of galaxies, Type 1a supernova are actually quite common in the night sky.
By observing the spectral lines from stars, astronomers long ago determined that stars and
intranebular gasses are made from the same stuff as the physical matter on Earth. Indeed, helium
was first discovered from analyzing starlight, and only afterwards discovered on Earth. Because
we know what the matter in the universe is made of, we can estimate the composition of the
matter in the universe. If we know how much matter there is, we can use simple physics to
determine how stars should attract one another, and hence determine the speed of various stars
and even galaxies. When this was done, it was found that stars far from the center of our galaxies
are moving much faster than predicted by the known mass of the stars in the universe. This is the
origin of "dark matter."
What is dark matter made of? If we measure the initial density of protons and neutrons arising
from the Big Bang (there was too much energy for the first 300,000 years of the universe to
support anything but a plasma of neutrons and protons), which we can do by measuring the
current abundance of very light atoms (hydrogen, helium, lithium), which were the first atoms to
appear after the universe cooled a bit, we find that the we are missing about half of the matter
that we should see. The other half presumably is part of the "dark matter." However this accounts
for only about 20% of what the amount of dark matter must be. What is the rest? No one knows.
The amount of dark matter is important because this amount determines whether our universe is
open, closed or flat. However, we don't know how much dark matter there is. So Krauss takes
another tack. The light from a star shows us what the star was like at the time the light was
emitted from the star. If we look at very far-away stars, we can peer far into the universe's past.
However, before age 300,000 years, the universe' matter was a hadron plasma that absorbed all
photons, so it is impossible to peer back farther than that. However, the 300,000 year surface of
the universe is "last scattering surface," and by measuring the density of matter on this surface,
we can tell whether the universe is open, closed, or flat. Why? Because gravitational clumping is
subject to the laws of gravity, and gravitational forces move at the speed of light. Therefore, we
can determine the actual maximum width of a clump, as measured on the last scattering surface.
If the universe is flat, we will observe exactly what we calculated. If the universe is open, light
rays will "fan out" from the last scattering surface, so clumps will look bigger. Similarly, if the
universe is close, lumps will look smaller. What we observe is compatible only with a flat
universe. Krauss's exposition here is just superb.
Given that the universe is flat, we can calculate that 70% of the energy is missing, being neither
visible matter nor dark matter. This is essentially Einstein's "cosmological constant," although
astronomers move this from the right side of the equation (curvature) to the left (energy). Krauss
argues that this "dark energy" is actually the energy of empty space (this is the "nothing" in the
title of the book).
Krauss here takes a long and beautiful detour into quantum mechanics explaining how the
uncertainty principle predicts that empty space is really a frothing turmoil of particle coming into
and out of existence, and reality of virtual particles is proved by their use in predicting the
spectral lines of hydrogen with an accuracy of one part in 100 billion.
If we calculate the energy in empty space, we get a figure that is 120 orders of magnitude larger
than all the energy in the universe. So this calculation is wrong, but no one knows why. Krauss
calls this the Cosmological Constant Problem. He makes a rather lame argument that the energy
of empty space must be zero after the frothiness cancels out (although perhaps it does).
Cryptically, a few pages later, he asserts that the missing energy must be not in the form of any
matter but empty space (p. 75), so I will disregard his lame argument.
Krauss explains why the universe is flat using Guth's inflation theory, which says that very early
in its existence, the universe underwent a phase transition that led it to increase a trillion-fold in
size in almost time (space can expand faster than the speed of light, although nothing in a give
space can travel faster than the speed of light). Whatever small amounts of curvature were
present at the inflation point would be obliterated by the inflation process. Therefore the universe
is flat.
Here is Krauss's main point: "Including the effects of gravity in thinking about the universe
allows objects to have... "negative" as well as "positive" energy....gravity can start out with an
empty universe---and end up with a filled one." (p.99) This is because the conservation of energy
allows for offsetting positive and negative energy. This seems like nothing new to me, and
hardly a revelation. Electron-positron pairs are created from nothing and can go their own ways,
so matter can be created from nothing.
This is where Krauss's theology/metaphysics comes in. Because the universe could have been
created from nothing (quantum fluctuation, empty space),there is no need to posit a Creator. But,
the theologian will ask, who created the rules according to which the Big Bang was regulated?
Krauss has no answer, except to say (a) there might be lots of different rules for different
universes, and (b) if you are going to posit an eternal preexisting Creator, you are no better off
that simply positing the eternal and preexisting laws of physics. But Krauss is wrong. When one
posits a Creator, one is admitting that one's knowledge has limits, and there are higher orders of
knowledge that are inaccessible to mere human intellect. We do not know anything about the
realms of being of the Creator or Creators, but we believe they must exist beyond the limits of
our understanding. Our reason for believing this is that we experience possessing forms of
knowledge inaccessible to other species (amoebae, mushrooms, field mice, Capuchin monkeys,
German Shepherds, chimpanzees, and such). It would be completely arbitrary to claim there is
no realm of intellect beyond ours. Simply positing the eternality of the laws of physics is, in
comparison, an unsatisfying alternative.
Here is Krauss's faith: "Without science, everything is a miracle. With science, there remains the
possibility that nothing is." (p. 183) I maintain that this is very likely incorrect, and hardly the
basis for a firm metaphysics.