Doctor who

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

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Doctor who

  1. 1. bbc.co.uk/doctorwhoFACT OR FANTASY?
  2. 2. Who Is Doctor Who?• Time Lord from PlanetGallifrey• Travels in space and time inthe T.A.R.D.I.S.• Can regenerate when facingdeath• Battles against evil enemies
  3. 3. Daleks!!!
  4. 4. Cybermen!!!
  5. 5. Slitheen!!!
  6. 6. And even more Daleks!!!
  7. 7. Can we all be time lords?3 easy steps to becoming a time lord…1. Work out how to travel time2. Build a time machine3. Make a sonic screwdriver
  8. 8. Can we all be time lords?3 easy steps to becoming a time lord…1. Work out how to travel time2. Build a time machine3. Make a sonic screwdriver Very cool…
  9. 9. Time TravelSpecial relativity light always travels at same speed for observer (3x108 ms-1)Time Dilation moving clocks tick slower than stationary ones
  10. 10. Oh no!
  11. 11. That’s just wrong!
  12. 12. Enough already!
  13. 13. Time TravelGeneral 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. 14. WormholesLink 2 regions of space with a wormhole, cunning…
  15. 15. WormholesWormhole instructions, please read carefully…1. Take 2 wormholes side by side2. Take one and accelerate it close to speed of light, keep the other one where it is3. Time dilation – clocks tick slower in moving mouth4. If you enter the stationary wormhole, you can come out of the moving one at an earlier time…
  16. 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 createdOK OK, spoil our fun.But can we at least move from different point in space?Can we teleport?
  17. 17. Teleportation• Uncertainty principle prevents it• We can’t simultaneously know theposition and momentum of a particle!• Same for energy and timeCan use quantum entanglement Take 2 subatomic particles Bring them together to get quantum states interlinked Separate them, one determines the other
  18. 18. Problems…• Human body has at least 1028 atoms• Would take 1013 years (that’s 4000times the age of the universe!)• Need receiverSo far have scientists have teleported photons
  19. 19. Can we all be time lords?3 easy steps to becoming a time lord…1. Work out how to travel time2. Build a time machine3. Make a sonic screwdriver Oh boy…
  20. 20. T.A.R.D.I.S.Time And Relative Dimensions In Space
  21. 21. How does that workThe tardis is bigger on inside than out… How? Use general relativity We can bend space and time to get a bubble bigger on sidethan out Can’t use normal particlesNeed exotic matter Particles that violate classical physics Have negative pressure, some even have a negative mass!!!
  22. 22. Chameleon Circuit• Need to blend in withsurroundings• Different to cloaking device• University of Tokyo hasdeveloped optical camouflage• System of cameras andprojectors• Camera technology isimproving
  23. 23. Electrostriction• Change shape and texture• Use electrostriction - non-conductors can changeshape under an electric field - can expand & contract by up to afactor of 5• Calculate electric field totransform shape into clock etc
  24. 24. Can we all be time lords?3 easy steps to becoming a time lord…1. Work out how to travel time2. Build a time machine3. Make a sonic screwdriver Very cool…
  25. 25. Sonic ScrewdriverCan do endless things…A great Father’s day presentWorks using sound waves,but what is sound?
  26. 26. Sound wavesSound is vibrationSound waves are longitudinal
  27. 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. 28. Sonic ScrewdriverNeed to make a narrow beamHave high frequency sound, so that beam is less spread out Speed = frequency * wavelengthUse principal of beats…
  29. 29. Beats• Take 2 waves of sameamplitude• BUT slightly differentfrequencies• Variation in amplitude =beats• Beat frequency fbeat = fa - fb• Produce audible sound
  30. 30. Be careful out there…

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