How Higgs Boson Gave Mass To The Universe?
The early universe was very hot and dense. All the matter we see today was created at the very first
moment of time almost 13 Billion years ago. In the early universe for one moment every particle was
massless. Then suddenly they weren’t massless anymore. All because of Higgs Boson. But how
did this happen? How was Higgs Boson able to give mass to the universe?
If we extrapolate back in time as far as possible, we'd come to a time before the first galaxies
formed; before the first stars ignited; before neutral atoms or atomic nuclei or even stable
matter could exist. The earliest moment at which we can describe our Universe as hot,
dense, and uniformly full-of-stuff is known as the Big Bang. The early universe was
filled with all the particles, antiparticles and radiation it had the energy to create.
As the universe expanded it cooled down, stretching the fabric of space and in turn
also stretching the wavelength of all radiations to longer wavelengths. The Universe was entirely
empty during inflation. There were no particles, substances, or photons; only empty space.
That empty space contains a tremendous quantity of energy, the exact amount of which varies
slightly over time. Those variations are stretched to bigger scales, while new,
small-scale oscillations emerge on top. The particles came after some-time in the equation.
If there are any particles (and antiparticles) at greater energies that were yet to be discovered,
they were most likely generated in the hot Big Bang, as long as there was enough energy
(E) available to create a massive (m) particle using Einstein's E = mc2. It's possible that new
physics at these early times will solve a slew of mysteries about our Universe,
such as the origin of matter-antimatter asymmetry and the formation of dark matter. However,
the huge particles we are familiar with today are alien to us. They have no mass in these
early phases. The particles and antiparticles of the Standard Model are easy to create,
even as the Universe cools down over a small period of time. The Universe may
have begun with energies as high as 10¹⁵ or 10¹⁶ GeV which gradually decreased over time.
We can today construct the whole suite of particle-antiparticle pairs known to physics
at the energies attained by the LHC. But in the early universe at this point, they were
all massless. They had no choice but to move at the speed of light if they had no rest mass.
What is the cause of particles being in this unusual, bizarre form that is
so different from how they are now? This is due to the fact that the basic symmetry that
gives rise to the Higgs boson — the electroweak symmetry — has not yet broken in the Universe.
When we look at the Standard Model today, it’s arranged as follows:
six quarks, each of which come in three colors, and their antiquark counterparts,
three charged leptons (e, μ, τ) and three neutral ones (v_e,
ν_μ, ν_τ), and their antimatter counterparts,
the eight massless gluons that mediate the strong force between the quarks,
the three heavy, weak bosons (W+, W-, and Z_0) that mediate the weak nuclear force,
and the photon (γ), the massless mediator of the electromagnetic force.
The electroweak symmetry, however, is violated at today's low-energy scale.
In the early days of the Universe, this symmetry was restored.
And when it is restored as opposed to shattered, the Standard Model view is profoundly altered.
Instead of the weak and electromagnetic bosons (W+, W-, Z_0, γ), the first three of which are
quite large and the fourth of which is massless, we have four new bosons for the electroweak force
(W_1, W_2, W_3, B), all of which have no mass at all. The other particles are identical,
except that they, too, do not yet have mass. This is what's going on in the early Universe,
colliding, annihilating, and spontaneously forming, all at the speed of light.
All of this continues as the Universe expands and cools. As long as the energy of our Universe is
above a specific threshold, you can imagine the Higgs field hovering atop the liquid in a soda
(or wine) bottle. As the liquid level falls, the Higgs field remains atop the liquid,
and everything remains massless. This is referred to as a restored-symmetry condition.
However, below a certain liquid level, the container's bottom begins to reveal
itself. And the field can no longer remain in the centre; more broadly,
it can no longer take on any old worth. It must travel where the liquid level is, which is down
into the divot(s) at the bottom of the bottle. This is referred to as a broken-symmetry state.
When this symmetry is broken, the Higgs field enters the bottom, lowest-energy,
equilibrium state. That energy state, however, is not quite zero: it has a limited,
non-zero value known as the vacuum expectation value. Whereas the restored-symmetry state
produced just massless particles, the broken symmetry state causes a complete transformation.
When the symmetry is broken, the Higgs field has four mass-containing consequences:
two of which are charged (one positive and one negative)
and two of which are neutral. Then the following events occur all at once:
The W_1 and W_2 particles “eat” the charged, broken-symmetry consequences of the Higgs,
resulting in the W+ and W- particles. The W_3 and B particles combine, with one eating
the uncharged broken-symmetry consequence of the Higgs, becoming the Z 0, and the other eating
nothing, remaining the massless photon (). The Higgs' final neutral broken-symmetry
consequence accumulates mass and becomes the Higgs boson.
Finally, the Higgs boson couples to all other particles.
This is the origin of mass in the Universe. This entire process is known as spontaneous symmetry
breakdown. When the Higgs symmetry for quarks and leptons in the standard model is broken,
every particle gains mass due to two factors: the expected value
of the Higgs field and A coupling constant. And this is where the issue arises. The Higgs
field expectation value is the same for all of these particles and is not difficult to calculate.
But what about that coupling constant? It is not only distinct for each particle, but it is also
arbitrary in the standard model. We know the particles have mass; we know how they gain mass;
and we've found the particles that cause mass. But we still don't know why the particles have
the masses that they have. We don't know why the coupling constants have the couplings they have.
The Higgs boson, the gauge bosons, and the quarks and leptons are all real.
We have exceptional abilities to produce, identify, and quantify their qualities. However,
knowing why they have the values that they do is a problem that we have yet to solve.
We don't know the solution. Everything known to exist in the Universe today
is massless and moves at the speed of light prior to the shattering of the electroweak symmetry.
When the Higgs symmetry breaks, mass is added to the Universe's quarks and leptons,
as well as the W and Z bosons and the Higgs boson itself. With such large mass differences
between light and heavy particles, the heavy ones spontaneously decay into the lighter ones on very
short timeframes, especially when the Universe's energy (E) falls below the mass equivalent (m)
required to form these unstable particles via E = mc². Existence would be impossible without this
essential gauge symmetry linked with electroweak symmetry breaking, because there are no stable,
bound states formed entirely of massless particles. But now that fundamental masses
have been assigned to quarks and charged leptons, the Universe can do something it has never done
before. It has the ability to cool and form bound states such as protons and neutrons.
It can cool even more, forming atomic nuclei and, finally, neutral atoms. And given enough time,
it can give birth to stars, galaxies, planets, and humans. None of this would be conceivable
without the Higgs boson, which provides mass to the Universe. Despite the fact that it took 50
years to discover, the Higgs boson has been making the Universe possible for 13.8 billion years.
To have such a phenomenon in our early universe was amazing.
We all owe our existence to the Higgs Boson or sometimes also known as the ‘The God Particle’.
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