1 / 24

Dr Sanjaye Ramgoolam

From Force & Matter to Strings. Dr Sanjaye Ramgoolam. In collaboration with. J. Bedford and C. Papageorgakis. STRING THEORY arises from attempts to answer:. 1) What is the world made of? 2) How & Why does the world change in time?. Answers:. 1) MATTER!

emackenzie
Télécharger la présentation

Dr Sanjaye Ramgoolam

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. From Force & Matter to Strings Dr Sanjaye Ramgoolam In collaboration with J. Bedford and C. Papageorgakis

  2. STRING THEORY arises from attempts to answer: 1) What is the world made of? 2) How & Why does the world change in time? Answers: 1) MATTER! E.g. Cars, Houses, Buildings, Planets… All matter has Mass

  3. 2) Forms of matter exert Forces on each other and they move under the influence of these forces For example: the attraction which causes an apple to fall off a tree.

  4. So far: 2 Questions 2 Answers MATTER ; FORCE

  5. Matter comes in millions of different forms: Apples, Oranges… Cars - Hondas BMWs... Garden Hoses, Grass, Trees... Earth, Sun, Moon… Galaxies, Planets, Stars... All this diversity in fact comes from only a few hundred atoms: Hydrogen, Oxygen, Nitrogen... • Each atom has a definite mass. • Each atom has an approximate size of about:

  6. By going from the large to the tiny, we reduce • the diversity of millions to around a hundred! • Things simplify further if we look • deeper into the atom: + Protons: Neutrons: Electrons: - Electrons orbit the nucleus which is composed of Protons and Neutrons

  7. The few hundred atoms reduce to only a • handful of fundamental objects • Our Millions of Matter objects have • been reduced to just 3 - Great! Unfortunately, the story starts to get more complicated: Proton & Neutron Quarks Colours red up down strange charm bottom top green + blue

  8. There are 3 ‘generations’ of these quarks • & each quark can have one of 3 different • ‘colours’ • Likewise there are 3 ‘generations’ of • electron-like objects called leptons: Leptons electron electron-neutrino muon muon-neutrino tau tau-neutrino

  9. The idea of String Theory is that this diversity of quarks and leptons comes from 1 String H O e p n e   u d s c t b 1 String

  10. What about Forces? “Hammer Force” “Fuel Force” “Astronomical Force” All this diversity of forces comes from: Gravity & Electromagnetism (& its 2 cousins)

  11. The Electric Force: • Rub a pen against your sleeve • & pick up pieces of paper. • Rubbing - Separation of charge. Matter contains positive & negative charges: Repulsion + + Repulsion - - Attraction + -

  12. On a grander scale: Lightning is caused by the Electric Force

  13. The connection between Light & Charge runs deep: Particle physics teaches us that “electrons repel because of the exchange of particles of light called photons” Exchange Repulsive force

  14. Particle physics reduces both Matter & Force to one kind of Entity i.e. particles. electrons Matter protons photons Forces gravitons Force of Gravity

  15. The Physics of particles is governed by “Quantum Mechanics” • Which brings about a Radical • Change in our concepts of • space. E.g. Cannot say electron is here and going nowhere. Every position is assigned a number telling us how likely the electron is to be at that point. x

  16. Quantum mechanical analogue of particle is here: The particle has maximum chances of being here and electrons in definite orbits is replaced by High chance of finding electron Small chance

  17. Deep inside proton: In addition to Electricity/Magnetism we need to know about Strong & Weak force. The mediators of strong forces are gluons. Quantum theory & particle physics do a great job of reducing diversity of matter & Electromagnetism, S & W forces to a few particles!

  18. Forces E.M. Strong Weak photons & gluons γ,g But gravity does not fit nicely into the Quantum Mechanical world. Applying Q.M. to gravitation gives infinities.

  19. String Theory combines all forces Strong,Weak, Gravitation, Electromagnetism & all matter electrons,protons,neutrons… into one object… …a String! Matter Force e-, p+, n γ, gluon, graviton

  20. How does a string accomplish this? • All particles have energy. In classical physics: I. also Rest energy ; II. Photons have frequency (related to colour of light) Planck’s constant

  21. Strings can vibrate in different ways For example: Guitar string Different vibration Different sound! • Fundamental string Different vibration Different particles! electron photon graviton

  22. In ordinary circumstances, we can understand • the world by applying different forces • according to the problem at hand. • A unified Theory of matter & forces is not just pretty - it is necessary for us to understand: • Physics of the Early Universe • Black Holes E.g. • Universe is expanding • Every galaxy is facing away from every other

  23. Going back in time, • All matter was crunched up in a very energetic state within a short distance. • Under these conditions all forces were equally important. • Hence String Theory becomes necessary for us to understand what happened at after the Big Bang.

  24. And it makes a startling prediction: The world contains… …Extra Dimensions!

More Related