- 3801 - PHYSICS - what is the “standard model”? The Standard Model explains the fundamental physics of how the universe works. It has endured over 50 trips around the sun despite experimental physicists constantly probing for cracks in the model's foundations.
--------------------- 3801 - PHYSICS - what is the “standard model”?-
- There is a bit more to be learned about how
the universe works. For example: Neutrinos represent three of the 17
fundamental particles in the Standard Model. They zip through every person on
Earth at all times of day.
-
- In 2021, physicists around the world ran a
number of experiments that probed the Standard Model. Teams measured basic
parameters of the model more precisely than ever before. Others investigated
the fringes of knowledge where the best experimental measurements don't quite
match the predictions made by the Standard Model. And finally, groups built
more powerful technologies designed to push the model to its limits and potentially
discover new particles and fields.
-
-The Standard Model of physics
allows scientists to make incredibly accurate predictions about how the world
works, but it doesn’t explain everything.
-
-In 1897, J.J. Thomson
discovered the first fundamental particle, the electron, using nothing more
than glass vacuum tubes and wires. More than 100 years later, physicists are
still discovering new pieces of the Standard Model.
-
-The Standard Model is a
predictive framework that does two things. First, it explains what the basic
particles of matter are. These are things like electrons and the quarks that
make up protons and neutrons.
-
- Second, it predicts how these matter
particles interact with each other using "messenger particles". These
are called bosons, photons and the famous Higgs boson, and they communicate the
basic forces of nature. The Higgs boson wasn't discovered until 2012 after
decades of work at CERN particle accelerator.
-
- The Standard Model is incredibly good at
predicting many aspects of how the world works, but it does have some
holes. It does not include any
description of gravity. While Einstein's theory of General Relativity describes
how gravity works, physicists have not yet discovered a particle that conveys
the force of gravity.
-
-
- A proper "Theory of Everything"
would do everything the Standard Model can, but also include the messenger
particles that communicate how gravity interacts with other particles.
-
- Another thing the Standard Model can't do is
explain why any particle has a certain mass.
Physicists must measure the mass of particles directly using
experiments. Only after experiments give physicists these exact masses can they
be used for predictions.
-
- Recently, physicists on a team at CERN
measured how strongly the Higgs boson feels itself. Another CERN team also measured the Higgs
boson's mass more precisely than ever before. And finally, there was also
progress on measuring the mass of neutrinos.
-
- Physicists know neutrinos have more than
zero mass but less than the amount currently detectable. A team in Germany has
continued to refine the techniques that could allow them to directly measure
the mass of neutrinos.
-
- Projects like the Muon g-2 experiment
highlight discrepancies between experimental measurements and predictions of
the Standard Model that point to problems somewhere in the physics.
-
- Projects like the Muon g-2 experiment
highlight discrepancies between experimental measurements and predictions of
the Standard Model that point to problems somewhere in the physics.
-In April 2021, members of the
Muon g-2 experiment at Fermilab announced their first measurement of the
magnetic moment of the muon. The muon is one of the fundamental particles in
the Standard Model, and this measurement of one of its properties is the most
accurate to date.
-
- The reason this experiment was important was
because the measurement didn't perfectly match the Standard Model prediction of
the magnetic moment. Basically, muons don't behave as they should. This finding
could point to undiscovered particles that interact with muons.
-
- In April 2021, physicist Zoltan Fodor showed
how they used a mathematical method called Lattice QCD to precisely calculate
the muon's magnetic moment. Their theoretical prediction is different from old
predictions, still works within the Standard Model and, importantly, matches
experimental measurements of the muon.
-
- The disagreement between the previously
accepted predictions, this new result and the new prediction must be reconciled
before physicists will know if the experimental result is truly beyond the
Standard Model.
-New tools will help
physicists search for dark matter and other things that could help explain
mysteries of the universe.
–
-First, the world's largest
particle accelerator, the Large Hadron Collider at CERN, was shut down and
underwent some substantial upgrades. Physicists just restarted the facility in
October, and they plan to begin the next data collection run in May 2022.
-
- The upgrades have boosted the power of the
collider so that it can produce collisions at 14 TeV, trillion electrpn
volts. This is up from the previous
limit of 13 TeV. This means the batches of tiny protons that travel in beams
around the circular accelerator together carry the same amount of energy as an
800,000-pound passenger train trading at 100 mph.At these incredible energies,
physicists may discover new particles that were too heavy to see at lower
energies.
-
Some other technological advancements were
made to help the search for dark matter. Many astrophysicists believe that dark
matter particles, which don't currently fit into the Standard Model, could
answer some outstanding questions regarding the way gravity bends around stars,
gravitational lensing, as well as the speed at which stars rotate in spiral
galaxies.
-
- The development of immense new detectors like
Hyper-Kamiokande and DUNE. Using these detectors, scientists will hopefully be
able to answer questions about a fundamental asymmetry in how neutrinos
oscillate. They will also be used to watch for proton decay, a proposed
phenomenon that certain theories predict should occur.
-
- 2021 highlighted some of the ways the
Standard Model fails to explain every mystery of the universe. But new
measurements and new technology are helping physicists move forward in the
search for the “Theory of Everything”
-
December 30, 2022 PHYSICS
- what is the “standard model” 3801
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