1. What have mathematicians done
for us?
Chris Budd

2. 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!

3. 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

4. Some ways that maths has changed the modern world
Maxwell: Electromagnetism … radio, TV, radar, mobile phones
Google
Galois
Matrices, eigenvalues
Error correcting codes

5. Mathematicians invented the computer!
Kelvin Tidal predictor
US Tidal predictor

6. An astonishing discovery!!!!!!!
Key idea ….
Write down the equations describing a physical system
Solve the equations
Predict the future
An astonishing discovery!!!!!!!

7. Navier-Stokes equations
Weather forecasting

8. Mathematicians save lives!
Florence Nightingale

9. 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

10. Radon 1917
Also used to
X-ray mummies
Detect land mines

11. 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)

12. Reason was discovered by Pythagaros
Length of strings giving C and G, and C and E, were in simple fractional proportions
C:C … 2/ C:G … 3/ C:E … 4/3

13. Pythagoras invented the Just Scale
Pythagoras invented the Just Scale .. Sequence of notes with frequencies in simple fractional proportions

14. 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

15. Bach so liked the new scale that he wrote the
Well Tempered Clavier to popularise it!
It is still used today!

16. A C E 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?

17. Now have 200 friends and want 100 to come to a party
Have a book saying who hates who
Who do you invite?
Parties to check
Takes a high speed computer
Years to check them

18. Using maths we can solve it in seconds
Simulated annealing
Works for a party and many other problems
SATNAV devices!

19. Conclusion …. your Life Music Party Future
Are safe in the hands of a mathematician