You have possibly heard of the Higgs boson. This indefinable
particle was expected to exist long ago and helped clarify why the Universe
works the way it does, but it took years for us to discover. Well, there is
another indefinable particle that has also been expected by quantum physics,
and it has been absent for an even longer time. In fact, we still have not
discovered one, and not through lack of trying. It is known as the magnetic
monopole, and it has a little unique property that makes it pretty special.
Those with curiosity in physics are possibly already
familiar with an electric monopole, though you may know it by its more famous
name: electric charge. Opposite electric charges attract and similar electric
charges repel through the interaction of electric fields, which are
well-defined as moving from positive to negative. These are the somewhat random
labels for the two opposite electric charges. Electric monopoles occur in the
form of particles that have a positive or negative electric charge, just like
protons or electrons.
At first glimpse, magnetism looks somewhat comparable to
electricity, as there exists a magnetic field with a direction defined as
moving from north to south. Though, the similarity breaks down when we try to
discover the magnetic matching part for the electric charge. Although we can
find electric monopoles in the form of charged particles, we have never
witnessed magnetic monopoles.
As an alternative, magnets are present only in the form of
dipoles with a north and a south end. When a bar magnet is divided into two
pieces, you do not get a discrete north part and a south part. In fact, you get
two new, smaller magnets, both with a north and south end. Even if you divided
that magnet down into single particles, you still develop a magnetic dipole.
When we look at magnetism in the world, what we see is completely stable with
Maxwell’s equations, which define the alliance of electric and magnetic field
theory into traditional electromagnetism.
They were originally published by James Maxwell throughout
1861 and 1862 and are still used every day on a practical level in engineering,
telecommunications, and medical uses, to name just a few. But one of these
equations, Gauss’s law for magnetism, says that there are no magnetic monopoles.
The magnetism we detect on a day-to-day basis can all be
ascribed to the movement of electric charges. When an electrically charged
particle moves along a track, just like as an electron moving down a wire, this
is an electrical current. This makes a magnetic field that wraps all over the
place, in the direction of the current. The second reason of magnetism includes
a property from quantum mechanics called 'spin'. This can be supposed of in
terms of an electrically charged particle revolving on an axis rather than
moving in a specific direction. This produces an angular momentum in the
particle, making the electron to act as a magnetic dipole (which is a small bar
magnet). This means we can explain magnetic spectacles without the need for
magnetic monopoles. But just for the reason that our classical electromagnetic
theories are reliable with our explanations, that does not indicate that there
are any magnetic monopoles.
Once we begin to explore the gloomy depths of theory, we
start to find some attractive arguments for their existence in the Universe. In
1894, Nobel Laureate Pierre Curie debated the possibility of such an
undiscovered particle and could find no cause to markdown its existence. Later,
in 1931, Nobel Laureate Paul Dirac presented that when Maxwell’s equations are
stretched to contain a magnetic monopole, electric charge can occur only in
discrete values. This 'quantisation' of electric charge is one of the
necessities of quantum mechanics. So Dirac’s effort went towards presenting
that classical electromagnetism and quantum electrodynamics were well-matched
theories in this logic.
Finally, there are few scientists who can struggle the
beauty of regularity in nature. And because the reality of a magnetic monopole
would indicate a duality between electricity and magnetism, the theory
signifying magnetic monopoles turn into almost intoxicating.
Duality, in the physical sense, is when two dissimilar
theories can be connected in such a way that one system is parallel to the
other. If it were the situation that the electric force was totally similar to
the magnetic force, then possibly other forces would also be similar to one
another. Perhaps then there would be some method to relate the strong nuclear
force to the weak nuclear force, paving the way to an outstanding alliance of
all physical forces. Just because a theory has an interesting regularity does
not make it correct.
An
individual magnetic monopole might be hiding out there somewhere. Credit:
CERN/MoEDAL
Researchers have come close to seeing magnetic monopoles by
creating monopole-like structures in the laboratory using difficult arrangements
of magnetic fields in Bose-Einstein condensates and super-fluids. But, though
these indicate that a magnetic monopole is not a physical impossibility, they
are not the similar as finding out one in nature. Particle physics researchers
have, on occasion, declared possible monopole candidates, but so far no one of
these discoveries has been revealed to be undisputable or reproducible.
The Monopole and Exotics Detector at the Large Hadron
Collider (MoEDAL) has taken up the exploration but has found no monopoles to
date. As a result, magnetic monopole devotees have turned their visions to
explaining why we have not discovered any monopoles. If the current generation
of particle accelerators have failed to identify a magnetic monopole, perhaps
the mass of a monopole is only greater than we are able to create at
present-day. Using theory, we can guess the maximum probable mass for the
magnetic monopole. Given what we already know about the arrangement of the
Universe, we can estimate that the monopole mass could be up to a massive 1014
TeV.
An object this huge may have been formed only in the very
first stages of the Universe after the Big Bang before cosmic inflation
started. If the Universe cooled to a time that monopole creation was no longer
vigorously possible before increasing, perhaps the monopoles are out there.
Just a few and far between. The trick is to discover one.
This article was initially published by The Conversation.
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