What have mathematicians done

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What have mathematicians done
for us?
Chris Budd
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A common scenario
You meet someone at a party and (foolishly) Tell
them you are a mathematician

• Their immediate reaction is to
• Panic
• Leave quickly
• Tell you that ..
• Mathematics is completely useless
• Mathematicians are souless geeks
• All mathematicians are mad!

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In response you can

• Deny that you are a mathematician
• Not go to any more parties
• Agree that mathematicians are evil
• or . Say that
• The modern world would not exist without maths
• With maths you can save lives
• Maths lies at the heart of art and music
• Mathematicians organise great parties

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Some ways that maths has changed the modern world
Maxwell Electromagnetism radio, TV, radar,
mobile phones
Google
Galois
Matrices, eigenvalues
Error correcting codes
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Mathematicians invented the computer!
US Tidal predictor
Kelvin Tidal predictor
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Key idea .

• Write down the equations describing a physical
  system
• Solve the equations
• Predict the future

An astonishing discovery!!!!!!!
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Navier-Stokes equations
Weather forecasting
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Mathematicians save lives!
Florence Nightingale
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Mathematics can look inside you
Modern CAT scanner
CAT scanners work by casting many shadows with
X-rays and using maths to assemble these into a
picture
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Radon 1917
Also used to X-ray mummies Detect land mines
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Mathematicians are good for music!
Some musical notes sound better when played
together than others
The octave C to C
The notes C and G (a perfect 5th) The notes C
and E (a perfect 3rd)
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Reason was discovered by Pythagaros
Length of strings giving C and G, and C and E,
were in simple fractional proportions
CC 2/1 CG 3/2 CE 4/3
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Pythagoras invented the Just Scale .. Sequence
of notes with frequencies in simple fractional
proportions
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Problem Keyboard instruments could only be tuned
for one key
Mathematicians invented a new Well Tempered scale
with all notes in the same proportion
a geometric progression which
works well in all keys
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Bach so liked the new scale that he wrote the
Well Tempered Clavier to popularise it! It is
still used today!
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Mathematicians organise great parties?
You have five friends, Annabel, Brian, Colin,
Daphne, Edward
Want to invite three to a party

• Annabel hates Brian and Daphne
• Brian hates Colin and Edward
• Daphne hates Edward

A C E
Who do you invite?
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Now have 200 friends and want 100 to come to a
party
Who do you invite?
Have a book saying who hates who
90000000000000000000000000000000000000000000000000
0000000000000000
Parties to check
Takes a high speed computer
6000000000000000000000000000000000000000
Years to check them
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Using maths we can solve it in seconds
Simulated annealing
Works for a party and many other problems
SATNAV devices!
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Conclusion . your

• Future
• Life
• Music
• Party

Are safe in the hands of a mathematician