014 HowIt Works http://www.howitworksdaily.com
IN ASSOCIATION WITHSpace-time ripples
could explain the universe
Words by Yasemin Saplakoglu0
ne of the universe’s biggest mysteries -
why there is more matter than
antimatter - may be a step closer to
being answered. That answer, in turn, could
explain why everything from atoms to black
holes exist.
Billions of years ago, soon after the Big
Bang, cosmic inflation stretched the tiny seed
of our universe and transformed energy into
matter. Physicists think inflation initially
created the same amount of matter and
antimatter, which annihilate each other on
contact. But then something happened that
tipped the scales in favour of matter, allowing
everything we can see and touch to come into
existence – and a new study suggests that the
explanation is hidden in very slight ripples in
space-time.
“If you just start off with an equal
component of matter and antimatter, you
would just end up with having nothing”
because antimatter and matter have equal
but opposite charge, said Jeff Dror, the lead
researcher at the University of California,
© AlamyBerkeley. “Everything would just annihilate.”
A new study may help answer one
of the universe’s biggest mysteriesObviously everything did not annihilate,
but researchers are unsure why. The answer
might involve very strange elementary
particles known as neutrinos, which don’t
have electrical charge and can thus act as
either matter or antimatter.
One idea is that about a million years after
the Big Bang, the universe cooled and
underwent a phase transition, an event
similar to how boiling water turns liquid into
gas. This phase change prompted decaying
neutrinos to create more matter than
antimatter by some “small, small amount,”
Dror said. But “there are no very simple ways- or almost any ways – to probe [this theory]
and understand if it actually occurred in the
early universe”.
But Dror and his team, through theoretical
models and calculations, figured out a way
we might be able to see this phase transition.
They proposed that the change would have
created extremely long and extremely thin
threads of energy called ‘cosmic strings’ that
still pervade the universe. Dror and his team
realised that these cosmic strings would most
likely create very slight ripples in space-time
called gravitational waves. Detect these
gravitational waves and we can discover
whether this theory is true.
The strongest gravitational waves in our
universe occur when a supernova, or star
explosion, happens; when two large stars
orbit each other or when two black holes
merge, according to NASA. But the proposed
gravitational waves caused by cosmic strings
would be much tinier than the ones our
instruments have detected before.
However, when the team modelled this
hypothetical phase transition under various
temperature conditions that could have
occurred during this phase transition, they
made an encouraging discovery. In all cases
cosmic strings would create gravitational
waves that would be detectable by future
observatories, such as the European Space
Agency’s Laser Interferometer Space Antenna
(LISA), the proposed Big Bang Observer and
the Japan Aerospace Exploration Agency’s
Deci-hertz Interferometer Gravitational wave
Observatory (DECIGO).SPACE