Physics for the 21st Century logo



Analogy for the Higgs Mechanism
The Higgs mechanism is analogous to a pond freezing over.
Annihilation and Creation of Particles
When an electron and its antiparticle collide, they annihilate and new particles are created.
ATLAS Components
The Electromagnetic Calorimeter, the Hadronic Calorimeter and the Muon Spectrometer, send different data to the trigger.
ATLAS Detector
ATLAS, the largest of the LHC's six detectors, weighs around 7,000 tons, is over five stories tall, and is 100 meters underground.
Electron-Electron Scattering
This movie shows the simplest way two electrons can scatter.
Gaps in the Standard Model
Perhaps the existence of particles or interactions still to be discovered could help explain gaps in the Standard Model.
Large Hadron Collider
The LHC is the largest and most complicated scientific machine ever created, generating data to advance our knowledge of the fundamental forces.
The LHC will operate with unprecedented luminosity—the measure used to express the number of collisions of protons per second.
Nambu-Goldstone boson
A wave in field space corresponds to a physical particle.
Proton Collisions
When two protons collide, any particle with a mass smaller than the collision energy can be created.
Quarks From the Vacuum
As two bound quarks are pulled apart, new quarks pop out of the vacuum.
Scattering Particles
A combination particle that's a mixture of type A and type B can be turned into a pure type A or pure type B particle when it interacts with matter.
Standard Model
The Standard Model, the best theory we have to describe the elementary particles and interactions, does not accommodate gravity.
Top Quarks and Leptons
Top quarks decay into lighter particles, which decay into lighter particles. Physicists must trace back through the decay chain.
Trigger and ATLAS Detectors
The trigger filters 40 million events down to 200 every second, using a three step process involving different ATLAS detectors.


Conservative and Non-conservative Forces
An example of conservative (right) and non-conservative (left) forces.
Faraday and Maxwell
Michael Faraday (left) and James Clerk Maxwell (right) unified electricity and magnetism in classical field theory.
Feynman, Richard
Richard Feynman was a major contributor to field of physics.
Ripples in Lake
Ripples in lake from a rock.
Super-Kamiokande Experiment
The nearly full water tank of the Super-Kamiokande experiment, which searches for nucleon decay.
Yang and Mills
Chen-Ning Yang and Robert Mills created a mathematical construct that lay the groundwork for future efforts to unify the forces of nature.

top of page


Beta Decay
An example of beta decay.
An extra dimension can curl up in a manner that is nearly impossible to discern for an inhabitant of the larger, uncurled dimensions.
Composite Higgs
This Feynman diagram representing a composite Higgs and top quark is a part of the Higgs mass calculation in a supersymmetric model.
Compton Scattering
Arthur Holly Compton (left) discovered that the frequency of light can change as it scatters off of matter.
Conserved Charge
The total amount of electric charge is conserved, even in complicated interactions like this one.
Elementary Particles
This chart shows the known fundamental particles—those of matter and those of force.
Feynman Diagram of a Jet
In this Feynman diagram of a jet, a single quark decays into a shower of quarks and gluons.
Feynman diagrams
Feynman diagram representing a simple scattering of two particles (left) and a more complicated scattering process involving two particles (right).
Friction, Close Up
A microscopic view of friction.
Gravitational Wave Detector
Schematic of a laser interferometer that can detect gravitational waves.
Mirror Symmetry
For the weak force, an electron's mirror image is a different type of object.
Neutralized Charges
Neutralized charges in QED and QCD.
Neutron Decay
Neutron decay from the inside.
Photoelectric Effect
When light shines on a metal, electrons pop out.
Proton Decay
The X boson mediates the decay of the proton.
QCD at Different Energies
The QCD coupling depends on energy.
QED Coupling
QED at high energies and short distances.
Reference Frames
Experimental results remain the same whether they are performed at rest or at a constant velocity.
Rotations in physical space and "particle space."
Scattering Cross Sections
Two examples of a scattering cross section.
Simulated Higgs Event
Simulation of a Higgs event at the LHC.
Canceling loops in supersymmetry.
Temperatures, Energies, and Lengths
Energies, sizes, and temperatures in physics, and in nature.
Spin flipping on the train.
Unification of Quarks and Leptons
Quarks and leptons, unified.
Unifying the Forces
In the Standard Model (left), the couplings for the strong, weak and electromagnetic forces never meet, while in supersymmetry (right), these forces unify near 1015 GeV.
W Boson Scattering
Scattering of W particles in Feynman diagrams.
The electromagnetic force and the constituents of matter.
Wine Bottle Potential
The wine-bottle potential that is characteristic of spontaneous symmetry breaking.
World as a Membrane
The Standard Model particles could be confined to the surface of a membrane, while gravity is free to leak into other dimensions.
Z Boson
The Z particle at SLAC.