Strange Universe Where Time Runs Backwards

A new unusual idea suggests that at the moment of the Big Bang,
a “mirror” Universe appeared along with ours, rushing along the
time axis in the opposite direction. Although in principle, it is
impossible to get into this anti-Universe, its existence should
manifest itself in the Universe in the form of a yet undiscovered
variety of neutrinos. Clusters of such neutrinos can create the
very dark matter whose particles cannot be found, despite all the
efforts of physicists (https://bit.ly/3tofCCt).
The hypothesis of the existence of a “mirror” universe was put
forward a few years ago by a team of scientists led by the famous
South African astrophysicist Neil Turok, who now works at the
University of Manchester (UK). Their new paper has been accepted
for publication in the Annals of Physics and made available in
the open online preprint library arXiv.org. It considers some of
the implications of this unusual idea, including dark matter.
The most fundamental symmetry in physics – CPT invariance - speaks
of the invariance of physical laws with simultaneous inversion of
charges (C), coordinates (P), and time (T). Science knows various
exceptions – violations of P- and C-symmetries, as well as their
various combinations.
For example, violation of CP invariance can lead to the dominance
of particles and the almost complete absence of antiparticles in the
Universe. However, no simultaneous violation of the CPT symmetry
has yet been discovered: if the charges, coordinates, and time are
reversed in the system, in principle, nothing will change for it.
Neil Turok and his co-authors have applied CPT invariance to the
universe itself. In such a hypothetical picture, our world turns out
to be only half of a binary system. Its CPT reverse twin travels
through time in the opposite direction, with opposite charges and
mirrored coordinates.
Calculations have shown that the existence of an anti-universe in
a “double” Universe makes it possible to quite simply explain the
existence of dark matter. This mysterious substance is not visible
to any scientific instrument, since it is able to interact with
ordinary matter only through gravity.
Dark matter can only be seen by the attraction of ordinary matter:
for example, along the trajectories of stars around an invisible
gravitating cluster. This makes it possible to map clumps of dark
matter on the scale of entire galaxies but does not make it possible
to capture and study the particles that make it up.
Until now, there are only hypothetical ideas about these particles.
And if we start from the fact that we live only in half of the
integral “double” CPT-invariant Universe, then one hypothesis
becomes more. Neil Turok and his colleagues showed that in this
case, new types of neutrinos should appear.
Today there are six of them (electron, muon, and tau neutrinos plus
their antiparticles with opposite charges), they all have a positive
spin, although the rest of the fundamental particles are both
positive and negative. But with the existence of a second
anti-universe, neutrinos with reverse spin must also exist.
They practically do not interact with ordinary matter in any way
and can only appear in very massive clusters, due to their gravity
- just like a hypothetical dark matter. According to the calculations
of Neil Turok and his colleagues, the number of such neutrinos
should be enough to observe all the necessary effects of dark matter.
The unusual hypothesis allows us to draw several testable conclusions
about the fundamental properties of neutrinos. In particular, it
predicts that at least one type of these particles must be massless.
So far, this question remains open: the experiments allowed us to
establish only the upper limit of neutrino masses. Perhaps new work
will help to clarify them completely – and we will receive the first
evidence in favor of the existence of a twin anti-Universe of our
own.