this does not belong to me. mine will be here next!

1. bbc.co.uk/doctorwho
FACT OR FANTASY?

2. Who Is Doctor Who?
• Time Lord from Planet
Gallifrey
• Travels in space and time in
the T.A.R.D.I.S.
• Can regenerate when facing
death
• Battles against evil enemies

3. Daleks!!!

4. Cybermen!!!

5. Slitheen!!!

6. And even more Daleks!!!

7. Can we all be time lords?
3 easy steps to becoming a time
lord…
1. Work out how to travel time
2. Build a time machine
3. Make a sonic screwdriver

8. Can we all be time lords?
3 easy steps to becoming a time
lord…
1. Work out how to travel time
2. Build a time machine
3. Make a sonic screwdriver
Very cool…

9. Time Travel
Special relativity
light always travels at same speed for observer (3x108 ms-1)
Time Dilation
moving clocks tick slower than
stationary ones

10. Oh no!

11. That’s just wrong!

12. Enough already!

13. Time Travel
General Relativity
Time travels more slowly for objects in gravitational fields
Space time gets distorted
Large objects bends space time more than light objects
Ah ha, that’s it!
We can curl time
back on itself!

14. Wormholes
Link 2 regions of space with a wormhole, cunning…

15. Wormholes
Wormhole instructions, please read carefully…
1. Take 2 wormholes side by side
2. Take one and accelerate it close to speed of light, keep the
other one where it is
3. Time dilation – clocks tick slower in moving mouth
4. If you enter the stationary wormhole, you can come out of
the moving one at an earlier time…

16. There may be a problem…
• Strong force of gravity acting on us
• Need to keep wormhole open for long enough
• Can’t visit time periods before time machine was created
OK OK, spoil our fun.
But can we at least move from different point in space?
Can we teleport?

17. Teleportation
• Uncertainty principle prevents it
• We can’t simultaneously know the
position and momentum of a particle!
• Same for energy and time
Can use quantum entanglement
Take 2 subatomic particles
Bring them together to get
quantum states interlinked
Separate them, one determines
the other

18. Problems…
• Human body has at least 1028 atoms
• Would take 1013 years (that’s 4000
times the age of the universe!)
• Need receiver
So far have scientists have teleported photons

19. Can we all be time lords?
3 easy steps to becoming a time
lord…
1. Work out how to travel time
2. Build a time machine
3. Make a sonic screwdriver
Oh boy…

20. T.A.R.D.I.S.
Time And Relative Dimensions In Space

21. How does that work
The tardis is bigger on inside than out… How?
Use general relativity
We can bend space and time to get a bubble bigger on side
than out
Can’t use normal particles
Need exotic matter
Particles that violate classical physics
Have negative pressure, some even have a negative mass!!!

22. Chameleon Circuit
• Need to blend in with
surroundings
• Different to cloaking device
• University of Tokyo has
developed optical camouflage
• System of cameras and
projectors
• Camera technology is
improving

23. Electrostriction
• Change shape and texture
• Use electrostriction
- non-conductors can change
shape under an electric field
- can expand & contract by up to a
factor of 5
• Calculate electric field to
transform shape into clock etc

24. Can we all be time lords?
3 easy steps to becoming a time
lord…
1. Work out how to travel time
2. Build a time machine
3. Make a sonic screwdriver
Very cool…

25. Sonic Screwdriver
Can do endless things…
A great Father’s day present
Works using sound waves,
but what is sound?

26. Sound waves
Sound is vibration
Sound waves are longitudinal

27. Sonic Screwdriver
• Use sound waves to undo screws
• We can hear 20-20,000 Hz,
above is ultrasound
• Ultrasonic hard drives
• Ultrasound is very harmful!
> 159dB = warms skin
> 180dB = lethal

28. Sonic Screwdriver
Need to make a narrow beam
Have high frequency sound, so that beam is less spread out
Speed = frequency * wavelength
Use principal of beats…

29. Beats
• Take 2 waves of same
amplitude
• BUT slightly different
frequencies
• Variation in amplitude =
beats
• Beat frequency
fbeat = fa - fb
• Produce audible sound

30. Be careful out there…