It may still be possible to understand what happened, even
when our science reaches its limit.
The evidence for the Big Bang is overwhelming, yet we cannot
truly describe what happens in that event. We cannot even call it a moment
because time as we know it did not exist. Our science stops making sense a
fraction of a second after it begins. The equations simply fail. But what if
there were a way to push them not only to their limits but beyond? That is what
researchers are now trying to do.
A team at the Foundational Questions Institute is using
complex computer simulations to solve Einstein’s equations numerically. This
method is often used to solve equations and problems that have no generalized
solution, such as the famous three-body problem. While relativity has exact
solutions in a variety of environments and situations, it breaks down at the
extreme. This is why it might be the crucial tool to push beyond the limits
science is currently struggling with.
Numerical relativity was first developed in the 1960s and
70s to solve the question of how black holes merge, and in particular, the
emission of gravitational waves. While relativity predicted the existence of
gravitational waves, showing what form those waves will take cannot be done on
paper and pen alone, no matter how well we know Einstein’s equations.
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Illustration of the Big Bang. |
It had already been ten years since the first detection of
gravitational waves, which showed that this approach to relativity could
successfully predict results even when we could not solve the equations
exactly. So why not apply the same approach to other problems?
“I am most excited about using numerical relativity to
explore how the Big Bang began, and how it can be used to solve some
long-standing problems in string theories,” co-author Professor Eugene Lim,
from King’s College London, told.
The work, which is almost entirely done with funding from
the UK Research Councils and Leverhulme Trust, is set to tackle the Big Bang
and the period known as Cosmic Inflation, which took place for a fraction of a
second after the beginning of the universe. The whole cosmos expanded at an
incredible rate.
The existence of this inflationary period is necessary to
explain how the universe is roughly the same everywhere we look. Without it, a
lot of other things fall apart in our understanding of the universe. The
problem is that we do not know what caused this inflation. That’s where
numerical relativity comes into play.
“[B]ecause inflation itself is not a full theory, but a
theory that must be derived from something more fundamental (in technical
terms, we call inflation an "effective theory"),” Lim explained to
IFLScience.
The approach has potential, and in the case of gravitational
waves, it delivered. Numerical solutions of cosmic inflation might reveal
conditions or requirements that could indicate fields, interactions, or
properties that transcend the expected confines of our universe. Several
theories, such as the cyclical universe (Big Bounce) and several multiverse
hypotheses, go beyond both the space and time of our universe. If these
hypotheses are correct, evidence might appear in these solutions.
That said, numerical relativity is not an easy task. We
would have already done it otherwise. Still, computational breakthroughs allow
for supercomputers to be up to the task, and the work to solve these problems
is now going full steam ahead.
The study was published in the journal Living Reviews inRelativity.