The Fabric of Reality David Deutch

particular string of ten molecules, in the special niche consisting of the rest of
the gene and 
its niche, is a replicator. It embodies a small but significant
amount of knowledge. Now suppose, for the sake of argument, that we can
find a junk-DNA (non-gene) segment in the bear’s DNA which also has the
sequence TCGTCGTTTC. Nevertheless this sequence is not; worth calling a
replicator, because it contributes almost nothing to its replication, and it
embodies no knowledge. It is a random sequence. So here we have two
physical objects, both segments of the same DNA chain, one of which
embodies knowledge and the other is a random sequence. But they are
physically identical. How can knowledge be a fundamental physical quantity,
if one object has it while a physically identical object does not?
It can, because these two segments are not really identical. They only look
identical when viewed from some universes, such as ours. Let us look at
them again, as they appear in other universes. We cannot directly observe
other universes, so we must use theory.
We know that DNA in living organisms is naturally subject to random
variations — 
mutations — in the sequence of A, C, G and T molecules.
According to the theory of evolution, the adaptations in genes, and therefore
the genes’ very existence, depend on such mutations having occurred.
Because of mutations, populations of any gene contain a degree of variation,
and individuals carrying genes with higher degrees of adaptation tend to
have more offspring than other individuals. Most variations in a gene make it
unable to cause its replication, because the altered sequence no longer
instructs the cell to manufacture anything useful. Others merely make
replication less likely (that is, they narrow the gene’s niche). But some may
happen to embody new instructions that make replication 
more likely. Thus
natural selection occurs. With each generation of variation and replication
the degree of adaptation of the surviving genes tends to increase. Now, a
random mutation, caused for instance by a cosmic-ray strike, causes
variation not only within the population of the organism in one universe, but
between universes as well. A cosmic ‘ray’ is a high-energy sub-atomic