may explain dark matter, dark energy and the black holes at the
core of many galaxies.
Andrzej Wojcicki / Science Photo Library / Getty
A new theory proposes that
faster-than-light particles known as
tachyons could answer a lot of questions about the universe.
Here are six big questions about
our universe that current physics can't answer:
1. What is
dark energy, the mysterious energy that appears to be
accelerating the expansion of the universe?
2. What is dark matter, the
invisible substance we can only detect by its gravitational effect
on stars and galaxies?
3. What caused inflation,
the blindingly fast expansion of the universe immediately after
the Big Bang?
4. For that matter, what caused the
5. Are there many possible Big Bangs
6. Is there a telltale characteristic
associated with the death
of a universe?
Despite the efforts of some of
the world's brightest brains,
the Standard Model of particle
physics, our current best theory of how the universe works at
a fundamental level, has no solution to these
A compelling new theory claims
to solve all six in a single sweep.
The answer, according to a paper published in
European Physical Journal C by
Herb Fried from Brown University
and Yves Gabellini
from INLN-Université de Nice,
may be a kind of particle called a
are hypothetical particles
that travel faster than light. According to
Einstein's special theory of relativity, and according
to experiment so far, in our 'real'
world, particles can never travel faster than light.
Which is just as well: if they did, our ideas about
cause and effect would be
thrown out the window, because it would be possible to
see an effect manifest before its
Although it is elegantly simple
in conception, Fried and
Gabellini's model is controversial because it requires
the existence of these tachyons:
specifically electrically charged,
fermionic tachyons and anti-tachyons,
fluctuating as virtual particles
in the quantum vacuum (QV).
(The idea of virtual particles
per se is nothing new: in the
Standard Model, forces like
electromagnetism are regarded as fields of
virtual particles constantly
ducking in and out of existence. Taken together, all
these virtual particles make
up the quantum vacuum.)
special relativity, though it
bars faster-than-light travel for
ordinary matter and photons,
does not entirely preclude the existence of
tachyons. As Fried
explains, "In the presence of
a huge-energy event, such as a supernova explosion or the Big
Bang itself, perhaps these virtual tachyons can be torn out of
the QV and sent flying into the real vacuum (RV) of our everyday
world, as real particles that have yet to be measured."
tachyons do cross the speed-of-light
boundary, the researchers believe that their high masses
and small distances of interaction would introduce into our world
an immeasurably small amount of 'a-causality'.
and Gabellini arrived
at their tachyon-based model
while trying to find an explanation for the
dark energy throughout space that appears to fuel the
accelerating expansion of the universe.
They first proposed that dark
energy is produced by fluctuations of
virtual pairs of electrons
However, this model ran into
mathematical difficulties with unexpected
imaginary numbers. In special
relativity, however, the rest mass of a
tachyon is an imaginary number,
unlike the rest mass of ordinary particles. While the
equations and imaginary numbers
in the new model involve far more than simple masses, the idea
is suggestive: Gabellini realized
that by including fluctuating pairs
of tachyons and
anti-tachyons he and Fried
could cancel and remove the unwanted
imaginary numbers from their calculations. What is more,
a huge bonus followed from this creative response to mathematical
necessity: Gabellini and
Fried realized that by adding their
tachyons to the model, they could explain
assumption [of fluctuating tachyon-anti-tachyon pairs] cannot
be negated by any experimental test," says
Fried, and the model fits beautifully with existing experimental
data on dark energy and
Of course, both
Fried and Gabellini
recognize that many physicists are wary of theories based on
such radical assumptions.
But, taken as a whole, their
model suggests the possibility of a unifying mechanism that gives
rise not only to inflation
and dark energy, but also
to dark matter. Calculations
suggest that these high-energy tachyons
would re-absorb almost
all of the photons they emit
and hence be invisible.
And there is more: as
Fried explains, "If a
very high-energy tachyon flung into the real vacuum (RV) were
then to meet and annihilate with an anti-tachyon of the same
species, this tiny quantum 'explosion' of energy could be the
seed of another Big Bang, giving rise to a new universe. That
'seed' would be an energy density, at that spot of annihilation,
which is so great that a 'tear' occurs in the surface separating
the Quantum Vacuum from the RV, and the huge energies stored
in the QV are able to blast their way into the RV, producing
the Big Bang of a new universe. And over the course of multiple
eons, this situation could happen multiple times."
This model, like any model of
such non-replicable phenomena
as the creation of the universe,
may be simply characterized as a tantalizing set of speculations.
Nevertheless, it not only fits with data on
inflation and dark energy,
but also offers a possible solution to yet another observed
Within the last few years, astronomers
have realized that the black hole
at the centre of our Milky
Way galaxy is 'supermassive',
containing the mass of a million
or more suns. And the same sort of
supermassive black hole (SMBH) may be seen at the centres
of many other galaxies in our current universe.
Exactly how such objects form
is still an open question. The energy stored in the
QV is normally large enough to counteract the gravitational
tendency of galaxies to collapse in on themselves. In the theory
of Fried and
Gabellini, however, when a
new universe forms, a huge amount of the
QV energy from the old universe escapes through the
'tear' made by the tachyon-anti-tachyon
annihilation (the new Big Bang). Eventually, even far
away parts of the old universe
will be affected, as the old universe's
QV energy leaks into the new universe like air escaping through
a hole in a balloon. The decrease in this
QV-energy buffer against gravity in the
old universe suggests that as the
old universe dies, many of its galaxies will form
SMBHs in the new universe,
each containing the mass of the
old galaxy's former suns and planets. Some of these new
SMBHs may form the centres
of new galaxies in the
may not be a very pleasant picture," says
Fried, speaking of the possible fate of our own universe.
"But it is at least scientifically
And in the weird, untestable
world of Big Bangs and
multiple universes, consistency may be the best we can
faster-than-light particles explain dark matter, dark energy,
and the Big Bang?
Robyn Arianrhod - 30 June 2017
About the Author: Robyn Arianrhod
is a senior adjunct research
fellow at the School of Mathematical
Sciences at Monash University.
Her research fields are general
relativity and the history
of mathematical science.