A fundamental law of nature may govern the growth of brain networks, social
networks, and the expansion of the Universe, a new computer simulation suggests.
The results, published Nov.16 in the journal Nature's Scientific Reports,
suggest that some undiscovered, fundamental laws may govern the growth of
systems large and small, from the electrical firing between brain cells and
growth of social networks to the expansion of galaxies.
Past studies showed brain circuits and the Internet look a lot alike. But
despite finding this functional similarity, nobody had developed equations to
perfectly predict how computer networks, brain circuits or social networks grow
over time, Krioukov said.
Using Einstein's equations of relativity, which explain how matter warps the
fabric of space-time, physicists can retrace the universe's explosive birth in
the Big Bang roughly 14 billion years ago and how it has expanded outward in
the eons since.
So Krioukov's team wondered whether the universe's accelerating growth could
provide insight into the ways social networks or brain circuits expand.
The team created a computer simulation that broke the early universe into the
tiniest possible units quanta of space-time more miniscule than subatomic
particles. The simulation linked any quanta, or nodes in a massive celestial
network, that were causally related. (Nothing travels faster than light, so if
a person hits a baseball on Earth, the ripple effects of that event could never
reach an alien in a distant galaxy in a reasonable amount of time, meaning
those two regions of space-time aren't causally related.)
As the simulation progressed, it added more and more space-time to the history
of the universe, and so its "network" connections between matter in galaxies,
grew as well, Krioukov said.
When the team compared the universe's history with growth of social networks
and brain circuits, they found all the networks expanded in similar ways: They
balanced links between similar nodes with ones that already had many
connections. For instance, a cat lover surfing the Internet may visit
mega-sites such as Google or Yahoo, but will also browse cat fancier websites
or YouTube kitten videos. In the same way, neighboring brain cells like to
connect, but neurons also link to such "Google brain cells" that are hooked up
to loads of other brain cells.
The eerie similarity between networks large and small is unlikely to be a
coincidence, Krioukov said.
"For a physicist it's an immediate signal that there is some missing
understanding of how nature works," Krioukov said.
It's more likely that some unknown law governs the way networks grow and
change, from the smallest brain cells to the growth of mega-galaxies, Krioukov
said.
"This result suggests that maybe we should start looking for it," Krioukov told
LiveScience.
http://www.space.com/18630-universe-grows-like-brain.html
