modern physics we do not know it all!!. general relativity einstein’s merging of special...
TRANSCRIPT
General Relativity• Einstein’s merging of Special
Relativity with Gravity, Space and Time.
• The math involved is super difficult!!
• Solved the problem with the orbit of Mercury, which Newtonian Mechanics never described with complete accuracy.
• All observations have confirmed the theory thus far.
Basic Ideas of General Relativity
• Space and time are merged into a single “fabric” called space-time.
• Gravity is caused by objects warping the fabric of space-time.
• Where there is more gravity, time is slower. Where there is less gravity, time is faster.
• Light is warped by gravity. This is used in gravitational lensing.
Quarks • Physicists now know protons and neutrons are not fundamental particles.
• Protons and neutrons are made of quarks, namely the up and down quarks.
• Six quarks are known to exist and each have an antiquark.
Quark Confinement• Quarks have never been observed in isolation,
which caused their existence to be doubted for a long time.
• Quarks either exist as a triplet (baryon) or a meson (quark/anti-quark pair).
• Latest calculations indicate a force of about 16 tons hold the quarks in a meson together.
The “Color” of Quarks
• Do not confuse this with color in the traditional sense, it is a quantum state.
• There are eight known colors of quarks but most common are red, green, and blue.
• These colors combine so that anything made of quarks is “colorless”.
Asymptotic Freedom
• It is the idea that the further apart quarks get from one another, the strong nuclear force gets even stronger.
• Quarks which are close to one another actually have some freedom to move about.
• In the 1970s these calculations saved to Standard Model of Particle Physics.
Leptons• Leptons include the very familiar electron, the muon, and the tau.
• μ and τ leptons are similar to electrons but heavier.
• Each has a corresponding neutrino, which are specific.
• νe
• νμ
• ντ
Fermions• Fermions are particles
which have a “spin” of ½.
• Namely Fermions are quarks and leptons.
• The Force Carriers, or Bosons, have a “spin” of 1.
• Do not confuse this “spin” with the traditional idea of spin.
More on Bosons• Photons, γ, carry electromagnetic
interactions, such as light.• The W and Z bosons are involved in weak
interactions, most familiar is nuclear radiation.• Gluons are involved in strong nuclear
interactions and have “color”. The study of gluons is a part of Quantum Chromodynamics (QCD).
No Gravity??• As of yet there is no
quantum definition of gravity.
• Gravity is so weak at the particle level it seems to be insignificant.
• Unification is the goal of combining General Relativity with Quantum Physics.
• The graviton boson has been proposed but there is no evidence.
Mesons
• Mesons most simply are a quark and anti-quark pair.
• Combined they are “colorless”.• They are involved in strong force
interactions.• They mediate interactions
between baryons and leptons.
Baryons• Baryons are structures composed of three
quarks.• A Baryon is “colorless”.• There have been hundreds of these
discovered, most of which decay quickly.• Protons and Neutrons are Baryons.• Mesons and Baryons together are known as Hadrons.