Godless
By
Steven Weinberg The New York Review of Books, September 25, 2008
Edited by Andy Ross
A tension between science and religion has been gradually weakening
serious religious belief, especially in the West, where science has been
most advanced. There are at least four sources of tension:
1 Religion originally gained
much of its strength from the observation of mysterious phenomena that
seemed to require the intervention of some divine being. But as time
passed more and more of these mysteries have been explained in purely
natural ways. We have not observed anything that seems to require
supernatural intervention for its explanation. There are some today who
cling to a God of the gaps. But as the gaps are filled in, their
position gives an impression of desperation.
2 These explanations have cast
increasing doubt on the special role of man as created by God to play a
starring part in a great cosmic drama. The discovery that humans arose
from earlier animals through natural selection acting on random
heritable variations is the one that continues most to disturb religious
conservatives. Both brain activity and behavior are in the same world of
objective phenomena, and I know of no obstacle to their being integrated
in a scientific theory.
3 Around 1100 CE, the Sufi
philosopher Abu Hamid al-Ghazzali argued against the very idea of laws
of nature, on the grounds that any such law would put God's hands in
chains. I wish I knew enough to judge how great was the impact on Islam
of his rejection of science. At any rate, science in Muslim countries
went into a decline in the century or two later. A recent survey found
just three areas in which the Islamic world produced excellent science:
desalination, falconry, and camel breeding.
4 Traditional religions
generally rely on authority, such as a prophet or a pope or an imam, or
a body of sacred writings. Scientists rely on authorities of a very
different sort. If I want to understand some fine point about the
general theory of relativity, I probably would not look up the original
papers of Einstein, because today any good graduate student understands
general relativity better than Einstein did. Heroes in science are not
infallible prophets.
Religious belief is only one aspect of the religious life. For many
people, the important thing about their religion is not a set of beliefs
but a host of other things. But I wonder how long religion can last
without its metaphysical beliefs.
For a physicist, it is a joy to
learn how we can use mathematics to understand the world. But we need
not worry that giving up religion will lead to a moral decline. Belief
in an omnipotent omniscient creator has no moral implications.
Physics
By
Steven Weinberg The New York Review of Books, November 7, 2013
Edited by Andy Ross
Cosmology first became a science when it was found that galaxies are all
rushing away from us and from each other. So once they were all crunched
together. The early universe must have been very hot and would have radiated
light that survived to the present as radiation cooled by expansion.
The cosmic microwave background radiation has a present temperature of 2.725
K. Calculations of the formation of the nuclei of atoms in the first three
minutes after the big bang predict a present abundance of light elements in
agreement with observation. Heavier elements are produced in stars.
There are small ripples in the temperature of the microwave radiation. These
ripples are due to chaotic sound waves in the early universe. When the
universe cooled to 3 kK it became transparent. The radiation bears the
imprint of the sound waves that filled the universe before it became
transparent.
The universe became transparent some 12 Ts after the
creation of atomic nuclei. The particles known to us are not enough to
account for the mass of the hot matter in which the sound waves must have
propagated. Five sixths of the matter of the universe seems to be dark
matter.
The dark matter had already been inferred from the fact that
clusters of galaxies hold together gravitationally. But the expansion of the
universe is speeding up. In the general theory of relativity, this is
explained by a dark energy that now makes up about three quarters of the
total energy of the universe.
The universe has been expanding for
13.8 billion years since it became transparent. In the standard cosmological
model, our expanding universe is mostly dark energy and dark matter. A few
percent of it consists of the ordinary matter that makes up the stars and
planets and us.
Elementary particle physics emerged from a deluge of
data. Quantum electrodynamics is a quantum field theory. The quantities
appearing in the fundamental equations are fields. Elementary particles are
the quanta of the fields. Photons are the quanta of the electromagnetic
field.
The quantum field theory of the weak nuclear force worked well
for previous data but gave nonsense at first when used to calculate the
rates of exotic processes. The electroweak theory says the weak nuclear
force is transmitted by the exchange of W and Z particles.
In the
electroweak theory there is an exact symmetry between weak and
electromagnetic forces, but the symmetry is broken by four proposed scalar
fields that permeate the universe, from which particles get masses. The
recently discovered Higgs particle is the quantum of one of these fields.
The strong nuclear force that holds protons and neutrons together inside
atomic nuclei suggests that three quarks combine to make up each proton and
neutron in an atomic nucleus. In quantum chromodynamics, the strong forces
between quarks are produced by the exchange of eight kinds of gluons.
The standard model of elementary particles includes quantum fields and
the various elementary particles that are the quanta of those fields: the
photon, three W and Z particles, eight gluons, six types of quarks, the
electron and two types of similar particles, and three kinds of neutrinos.
The standard model is not the final theory. Its equations involve a
score of numbers that have to be taken from experiment without our
understanding why they are what they are. It does not include gravitation.
We commonly describe gravitation using the general theory of relativity, but
this is not a quantum theory.
In the 13.8 billion years since the
universe became transparent there has not been time for radiation to have
connected and homogenized all the parts we see. So we think the universe
inflated exponentially at first. Tiny uniform regions would have inflated to
become larger than our present observed universe.
Inflation is
naturally chaotic. Quantum fluctuations during inflation would trigger just
the sort of chaotic sound waves we find in the cosmic radiation background.
Bubbles form in the expanding universe, each developing into a big or small
bang. The ocean of all these bubbles is the multiverse.
String theory
incorporates gravitation, it contains no infinities, and its structure is
tightly constrained by mathematics. But the equations of string theory have
a vast number of solutions. Different bubbles may realize all the different
solutions. We live in a bubble allowing the evolution of life and
intelligence.
AR This is a masterful summary, as one would
expect.
|