FACT OR FANTASY? bbc.co.uk/doctorwho
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 Who Is Doctor Who?
Daleks!!!
Cybermen!!!
Slitheen!!!
And even more Daleks!!!
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
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…
Time Travel Special relativity light always travels at same speed for observer (3x10 8 ms -1 ) Time Dilation moving clocks tick slower than stationary ones
Oh no!
Thats just wrong!
Enough already!
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, thats it! We can curl time back on itself!
Wormholes Link 2 regions of space with a wormhole, cunning…
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…
There may be a problem… Strong force of gravity acting on us Need to keep wormhole open for long enough Cant 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?
Teleportation Uncertainty principle prevents it We cant 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
Problems… Human body has at least atoms Would take years (thats 4000 times the age of the universe!) Need receiver So far have scientists have teleported photons
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…
Time And Relative Dimensions In Space T.A.R.D.I.S.
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 Cant use normal particles Need exotic matter Particles that violate classical physics Have negative pressure, some even have a negative mass!!!
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
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
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…
Sonic Screwdriver Can do endless things… A great Fathers day present Works using sound waves, but what is sound?
Sound waves Sound is vibration Sound waves are longitudinal
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
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…
Beats Take 2 waves of same amplitude BUT slightly different frequencies Variation in amplitude = beats Beat frequency f beat = f a - f b Produce audible sound
Be careful out there…