# Big Bangs and Dark Matter Dr Alan Barr Physics lecturer University of Oxford.

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Big Bangs and Dark Matter Dr Alan Barr Physics lecturer University of Oxford

Hubble The very BIG

Spectra and redshifts

Mega parsec = 3.26 million light-years = 3.1 x 10 16 m

Echos of something big WMAP satellite

What was formed: matter Differences between materials are due simply to the number of protons and electrons in their atoms. Only three elements are formed in the Big Bang All other elements are formed in stars

cell nucleus: 10 μm The very SMALL (what we see) cells: 50 μm dna: 2 nm atom nucleus: 2 fm x 5 x 20 atom: 100 pm x 50000 proton x 10000 x 5-> A hundred billion atomic nuclei lined up in a row would be the width of a human hair

The whole story?

The bit we understand… Matter & Forces Electron, e d quark Photon, γ Gluon, g Not to scale! Commonplace particles u quark Matter Particles u Quarks d c s t b Leptons νeνe νμνμ ντντ e μ τ Force carriers WZ γ g  Components and theory largely understood (maths)  Underlie all of physics, astronomy, chemistry, life! Out there? h G

Where do the particles get their mass from? Where has all the anti-matter gone? What is dark matter made of? What else is out there? Big questions NEED HIGH ENERGY COLLISIONS!

Blue Peter guide  Take some protons Lots of these in nature!  Make them move (very fast)  Bang them together It’s good to stand back at this point  Photograph the debris Your camera-phone may not be fast enough!

Our accelerator 1232 magnets each 8-Tesla bend protons in a circle Electric waves speed particles up The Large Hadron Collider, CERN Geneva (Swiss-French boarder) Large Hadron Collider

Note concerning “high energy” Spark could jump 5000 km in air (~radius of The Earth)

Our detectors LHCb ATLAS

Where do the particles get their mass from? Where has all the anti-matter gone? What is dark matter made of? What else is out there? Big questions

Mass and the “Higgs Boson” In this analogy the Higgs Boson is a treacle-ball – something which allows us to see the treacle itself Endows space with a kind of all-pervasive sticky-treacle Interactions with this treacle gives mass to particles They then travel slower than the speed of light The Higgs Field High energy collisions ought to make Higgs Bosons

The “tentative” evidence

What is Dark Matter? Normal: Made from atoms Includes stars, planets, people… Dark matter:Unknown substance (not atoms) May be a “fat cousin” of normal light We hope to make & study it at CERN Dark energy:Even weirder! Need to “see” the invisible!

How to “see” the invisible? proton short-lived exotic Invisible exotic Visible particle missing z x

Useful? Future discoveries will lead to new technologies Uses of the electron

Big Bangs and Dark Matter Astronomy  very large (See what’s out there) Particle physics  very small (Do it “at home”) Both explore the structure, building blocks and evolution of the universe Complementary information New discoveries lead to new technologies

Source of protons? Hydrogen gas Hydrogen molecules Electron “gun” Electron cloud Protons

Speed up and bend e-e- Accelerate Bend E-field B-field

Understanding the elements lets us make…

Discovery of the electron First subatomic particle to be isolated, in 1897 J.J.Thompson needed just over 13 V to remove electrons from atoms.

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