In order to comprehend the circumstances that led to the world as it is
today, scientists are trying to recreate the quark-gluon plasma, an early
form of matter.
A bang launched everything into life at the beginning of our universe. But
it's unclear what took place after that. Scientists believe that a hot,
soupy mixture of two basic particles called quarks and gluons, moving
through space as a plasma, likely existed before atoms or even the protons
and nuclei that make up an atom formed. Additionally, a group of scholars
are attempting to rewrite history because no one was present to witness the
creation of the universe.
They have basically produced a "Little Bang" using the Relativistic Heavy
Ion Collider at Brookhaven National Laboratory and are using it to
investigate the characteristics of that quark-gluon plasma. The discoveries
will contribute to the improvement of cosmologists' still hazy understanding
of the early universe and how the oozy, blistering condition of baby matter
cooled and formed into the planets, stars, and galaxies of today.
According to scientist Rongrong Ma, who works with the Solenoidal Tracker
at the Relativistic Heavy Ion Collider, or STAR, a detector dedicated to
studying the quark-gluon plasma, "we think about a microsecond after the Big
Bang, the universe was in this stage." Therefore, if we can learn from
experiments about the characteristics of such matter, that will help us
comprehend how the cosmos developed.
The duration of this plasma stage is unknown to scientists; it may have
ranged from a few seconds to millions of years. Knowing its characteristics
could help define the physics of the most extreme cosmic settings. It might
even still exist today in the dense centers of neutron stars or be created
when super-high energy particles collide with Earth's atmosphere.
Since observatories can only observe the cosmic microwave background—the
first light to appear from the dense early universe a hundred thousand years
after the Big Bang—their ability to research the early universe is limited.
Everything prior to that is a dark period of astronomy, both physically and
metaphorically. Nuclear physicist Jaki Noronha-Hostler of the University of
Illinois at Urbana-Champaign notes that theoretical models can fill in that
void, but detectors like STAR "allow you to experimentally understand a
system that's very similar to the Big Bang."
Furthermore, quarks and gluons are never discovered alone in nature, which
makes it challenging to research them separately. According to Helen Caines,
a physicist at Yale University and spokesman for the STAR experiment, "We
can't just pluck one out and examine it." Protons, neutrons, and more
unusual matter like upsilon, pion, and kaons are instead trapped in
composite forms. However, the separation between these compound particles
blurs at high enough temps. Caines adds, "And that is the quark-gluon
plasma." The quarks and gluons in this area are still contained within a
certain volume, but they are no longer joined together. In reality, she
claims, the term "plasma" may be a little misleading because it actually
functions more like a fluid and moves.
Physical Review Letters
published
a paper in March by Brookhaven researchers describing their creation of the
quark-gluon plasma for a moment in time by accelerating two streams of gold
nuclei almost to the speed of light and slamming them into one another. Then
came the smart part: they calculated how hot the post-Big Bang plasma would
have been using this impact.
In order to accomplish this, they had to search for upsilons, which are a
result of Brookhaven beam impacts but weren't actually present at the
beginning of the universe. A quark and its antimatter counterpart are bonded
together to form an upsilon in one of three ways: in a closely bound "ground
state," or in two excited states, one of which is looser than the other. The
gold atoms are abundant in each of these three forms when they are slammed
together.
The goal, according to Caines, is to use these fragments as a gauge. These
upsilons can be destroyed in a plasma similar to the one that might have
existed microseconds after the Big Bang; interactions with unbound quarks
and gluons will reduce them to their most elementary components.
Furthermore, each jurisdiction has a unique "melting point." The
quark-antiquark couples that are more loosely linked would require less
energy to disintegrate, while ground-state upsilons would require the most
energy and the highest temperatures. Therefore, simulating post-Bang plasma
conditions and noting how many upsilons of each state remained would provide
information about the temperature during the universe's creation.
Due to the fact that the temperature of the quark-gluon plasma is
inextricably connected to its density, pressure, and viscosity, this would
then provide scientists with information about other aspects of the plasma.
A mathematical formula that describes all of the characteristics of the
plasma, how they interact with one another, and how they change over time is
what scientists refer to as an equation of state.
The structure of the quark-gluon plasma is special: It has a circumference
similar to that of a proton, according to Noronha-Hostler, and is both
incredibly hot and small. It therefore defies the rules that govern how
fluids behave. She claims that while we can write down formulae, we cannot
answer them. Cosmologists can infer how long the universe must have been in
this soupy state by understanding this behavior, as well as what physical
processes led to a transition into the more recognizable protons, neutrons,
and other particles that make up matter today.
The first test was performed in 2012 using the Large Hadron Collider at
CERN, which can accelerate electrons to velocities that are 25 times greater
than those attained at Brookhaven. This was actually the second time that
scientists had conducted such a test. Scientists can fine-tune theoretical
models of the early universe by studying the plasma at lower energies to
better understand how its characteristics rely on temperature. According to
Brookhaven physicist David Morrison, who was not engaged in the research,
"In the field that we're in, you really want to do things at a range of
energies," However, the lower temperature state created at Brookhaven is
closer to what the system may have looked like when the quarks and gluons
started to combine. Hotter plasma is a superior probe for earlier in the
cosmos.
This time, following the impact of gold atoms in the STAR detector, the
researchers tallied the number of upsilons they observed in each state and
compared it to the expected number, prior to the plasma melting the
upsilons. About 60% of the upsilons in the ground state and 70% of those in
the intermediate state were discovered to be gone and likely dissolved. The
most weakly bound quark and antiquark duo upsilons appeared to be entirely
gone.
The STAR team's
earlier observations, which established an upper limit on the temperature required to create
the plasma: at least a trillion degrees, were supported by their recently
acquired data. (That is almost a million times hotter than the sun's core.)
This temperature was maintained by their atom breaking for just 10-23 of a
second.
In order to determine whether the particles with the loosestly bound
quark-antiquark pair genuinely disappeared or simply survived at rates too
low to be identified, the STAR team is preparing to repeat their upsilon
measurement at Brookhaven with about 20 times more data. Within the next
month, the facility will also activate a separate detector dubbed sPHENIX.
The 1,000-ton device, which is centered on an ultracold, superconducting
magnetic core, will enable more accurate study of this melting phenomenon.
Morrison, a representative for the sPHENIX partnership, claims that "This
STAR paper had hundreds of upsilons." "Tens of thousands will be
measured,"
When attempting to comprehend the characteristics of the quark-gluon
plasma, upsilons are ultimately just one piece of the jigsaw, according to
Ma. In addition, physicists can observe individual quark collisions, examine
photons coming from the plasma, or attempt to ascertain the kinds and rates
of other particles produced by the explosions of gold atoms. These various
observations will assist physicists in linking events they are already
familiar with to theories for those they are not. To create a complete
picture of the quark-gluon plasma, Ma explains, "we try to put all these
together, using a multi-messenger approach for a theory that can explain
everything."
