From New Atlas, May 2:
Renowned physicist Stephen Hawking
passed away earlier this year, but his legacy to science will live on.
His final theory on the origin of the universe has now been published,
and it offers an interesting departure from earlier ideas about the
nature of the "multiverse."
Ideas about how the universe came to
exist the way we see it today have been adapted and built on for
decades. The new paper, authored by Hawking and Professor Thomas Hertog,
adds to the literature with a new understanding of a theory known as
eternal inflation.
After the Big Bang kickstarted
the universe, it expanded exponentially for a brief fraction of a
fraction of a second. When that inflationary period ended, the universe
continued to expand at a much slower rate. But according to the eternal
inflation model, quantum fluctuations mean that in some regions of the
universe, that rapid inflation never stopped. That results in a gigantic
"background" universe full of an infinite number of smaller pocket
universes – including the one we live in.
"The usual theory of
eternal inflation predicts that globally our universe is like an
infinite fractal, with a mosaic of different pocket universes, separated
by an inflating ocean," Hawking has previously said. "The local laws of
physics and chemistry can differ from one pocket universe to another,
which together would form a multiverse. But I have never been a fan of
the multiverse. If the scale of different universes in the multiverse is
large or infinite the theory can't be tested."
For
an idea to be considered scientifically sound, it needs to make
predictions that are testable, so experiments can either prove or
disprove it. Otherwise, science starts to sound a whole lot like
religion – after all, the notion that God created everything in seven
days is also elegant and answers all the questions about our existence,
but is inherently untestable.
With that in mind, some
scientists, including Hawking and Hertog, take that to mean the eternal
inflation theory can't be considered without some modification. And that
modification is the focus of the new paper....MUCH MORE
