While challenging the Platonic dream of theoretical physicists, the
multiverse idea does explain one aspect of our universe that has
unsettled some scientists for years: according to various calculations,
if the values of some of the fundamental parameters of our universe were
a little larger or a little smaller, life could not have arisen. For
example, if the nuclear force were a few percentage points stronger than
it actually is, then all the hydrogen atoms in the infant universe
would have fused with other hydrogen atoms to make helium, and there
would be no hydrogen left. No hydrogen means no water. Although we are
far from certain about what conditions are necessary for life, most
biologists believe that water is necessary. On the other hand, if the
nuclear force were substantially weaker than what it actually is, then
the complex atoms needed for biology could not hold together. As another
example, if the relationship between the strengths of the gravitational
force and the electromagnetic force were not close to what it is, then
the cosmos would not harbor any stars that explode and spew out
life-supporting chemical elements into space or any other stars that
form planets. Both kinds of stars are required for the emergence of
life. The strengths of the basic forces and certain other fundamental
parameters in our universe appear to be “fine-tuned” to allow the
existence of life. The recognition of this finetuning led British
physicist Brandon Carter to articulate what he called the anthropic
principle, which states that the universe must have the parameters it
does because we are here to observe it. Actually, the word anthropic,
from the Greek for “man,” is a misnomer: if these fundamental
parameters were much different from what they are, it is not only human
beings who would not exist. No life of any kind would exist.
...
On one thing most physicists agree: If the amount of dark
energy in our universe were only a little bit different than what it
actually is, then life could never have emerged. A little more and the
universe would accelerate so rapidly that the matter in the young cosmos
could never pull itself together to form stars and thence form the
complex atoms made in stars. And, going into negative values of dark
energy, a little less and the universe would decelerate so rapidly that
it would recollapse before there was time to form even the simplest
atoms.
Here we have a clear example of fine-tuning: out of all the
possible amounts of dark energy that our universe might have, the actual
amount lies in the tiny sliver of the range that allows life. There is
little argument on this point. It does not depend on assumptions about
whether we need liquid water for life or oxygen or particular
biochemistries. As before, one is compelled to ask the question: Why
does such fine-tuning occur? And the answer many physicists now believe:
The multiverse. A vast number of universes may exist, with many
different values of the amount of dark energy. Our particular universe
is one of the universes with a small value, permitting the emergence of
life. We are here, so our universe must be such a universe. We are an
accident. From the cosmic lottery hat containing zillions of universes,
we happened to draw a universe that allowed life. But then again, if we
had not drawn such a ticket, we would not be here to ponder the odds.
...
Not only must we accept that basic properties of our
universe are accidental and uncalculable. In addition, we must believe
in the existence of many other universes. But we have no conceivable way
of observing these other universes and cannot prove their existence.
Thus, to explain what we see in the world and in our mental deductions,
we must believe in what we cannot prove.
Sound familiar? Theologians are accustomed to taking some
beliefs on faith. Scientists are not. All we can do is hope that the
same theories that predict the multiverse also produce many other
predictions that we can test here in our own universe. But the other
universes themselves will almost certainly remain a conjecture.
It's amazing how people with such smarts can appear to be so stupidly myopic. Thank God I'm not an atheist. Read the rest here.
12/22/2011
More to wrap your brain around
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