If a new theory turns out to be true, the
universe may not have started with a bang.
In the new formulation, the universe was never
a singularity, or an infinitely small and infinitely
dense point of matter. In fact, the universe may
have no beginning at all.
"Our theory suggests that the age of the
universe could be infinite," said study co-author
Saurya Das, a theoretical physicist at the
University of Lethbridge in Alberta, Canada.
The new concept could also explain what dark
matter — the mysterious, invisible substance
that makes up most of the matter in the
universe — is actually made of, Das added. [ The
Big Bang to Civilization: 10 Amazing Origin
Events ]
Big Bang under fire
According to the Big Bang theory , the universe
was born about 13.8 billion years ago. All the
matter that exists today was once squished into
an infinitely dense, infinitely tiny, ultra-hot point
called a singularity. This tiny fireball then
exploded and gave rise to the early universe.
The singularity comes out of the math of
Einstein's theory of general relativity, which
describes how mass warps space-time, and
another equation (called Raychaudhuri's
equation) that predicts whether the trajectory of
something will converge or diverge over time.
Going backward in time, according to these
equations, all matter in the universe was once
in a single point — the Big Bang singularity.
But that's not quite true. In Einstein's
formulation, the laws of physics actually break
before the singularity is reached. But scientists
extrapolate backward as if the physics equations
still hold, said Robert Brandenberger, a
theoretical cosmologist at McGill University in
Montreal, who was not involved in the study.
"So when we say that the universe begins with
a big bang, we really have no right to say
that," Brandenberger told Live Science.
There are other problems brewing in physics —
namely, that the two most dominant theories,
quantum mechanics and general relativity, can't
be reconciled.
Quantum mechanics says that the behavior of
tiny subatomic particles is fundamentally
uncertain. This is at odds with Einstein's general
relativity, which is deterministic, meaning that
once all the natural laws are known, the future
is completely predetermined by the past, Das
said.
And neither theory explains what dark matter ,
an invisible form of matter that exerts a
gravitational pull on ordinary matter but cannot
be detected by most telescopes, is made of.
Quantum correction
Das and his colleagues wanted a way to resolve
at least some of these problems. To do so, they
looked at an older way of visualizing quantum
mechanics, called Bohmian mechanics. In it, a
hidden variable governs the bizarre behavior of
subatomic particles. Unlike other formulations of
quantum mechanics, it provides a way to
calculate the trajectory of a particle.
Using this old-fashioned form of quantum
theory, the researchers calculated a small
correction term that could be included in
Einstein's theory of general relativity. Then,
they figured out what would happen in deep
time. [ 8 Ways You Can See Einstein's Theory of
Relativity in Real Life ]
The upshot? In the new formulation, there is no
singularity, and the universe is infinitely old.
A way to test the theory
One way of interpreting the quantum correction
term in their equation is that it is related to the
density of dark matter, Das said.
If so, the universe could be filled with a
superfluid made of hypothetical particles, such
as the gravity-carrying particles known as
gravitons, or ultra-cold, ghostlike particles
known as axions, Das said.
One way to test the theory is to look at how
dark matter is distributed in the universe and
see if it matches the properties of the proposed
superfluid, Das said.
"If our results match with those, even
approximately, that's great," Das told Live
Science.
However, the new equations are just one way
to reconcile quantum mechanics and general
relativity. For instance, a part of string theory
known as string gas cosmology predicts that the
universe once had a long-lasting static phase,
while other theories predict there was once a
cosmic "bounce," where the universe first
contracted until it reached a very small size,
then began expanding, Brandenberg said.
Either way, the universe was once very, very
small and hot.
"The fact that there's a hot fireball at very early
times: that is confirmed," Brandenberg told Live
Science. "When you try to go back all the way
to the singularity, that's when the problems
arise."
The new theory was explained in a paper
published Feb. 4 in the journal Physical Letters B,
and another paper that is currently under peer
review, which was published in the preprint
journal arXiv .
Follow Tia Ghose on Twitter and Google
+ . Follow LiveScience @livescience , Facebook &
Google+ .