Time & quantum mechanics

Chestnut Hill Book Festival, 20101

John Ashmead

Saturday, July 10, 2010

Lord Kelvin’s two small problems

2

Black body radiation Properties of

light

Saturday, July 10, 2010

• Time stretches,

• Breaks,

• And turns back on itself.

3

Saturday, July 10, 2010

4

Saturday, July 10, 2010

Michelson-morley

5

Saturday, July 10, 2010

Relativity

• speed of light constant

• laws of physics the same for all observers*

*but definition of simultaneity may differ!

Saturday, July 10, 2010

Twin paradox

7

Saturday, July 10, 2010

8

Saturday, July 10, 2010

9http://www.youtube.com/watch?v=f0VOn9r4dq8

Time seriously twisted

Saturday, July 10, 2010

Black hole at the center of the galaxy

10

Saturday, July 10, 2010

Black Holes Should Generate Ring of Light

11http://www.technologyreview.com/blog/arxiv/25182/Saturday, July 10, 2010

Falling into a black hole

12

Saturday, July 10, 2010

How to build a time

machine

13

Saturday, July 10, 2010

14

Visser's recipe for a time machine:

Acquire a traversable wormhole

Induce a "time-shift" between the two mouths of the wormhole

Bring the wormhole mouths together

Saturday, July 10, 2010

Closed time-like

curves

15

Saturday, July 10, 2010

16

Why pick on grandfather? It seems that the only way to prove that time travel is impossible is to cite a case of killing one's own grandfather. This incessant murdering of harmless ancestors must stop. Let's see some wide-awake fan make up some other method of disproving the theory.” – letter to Astounding Stories

Saturday, July 10, 2010

Saturday, July 10, 2010

Quantum mechanics

18

• Black body radiation

• Atoms

• The double slit experiment

Saturday, July 10, 2010

Black body radiation

19

Saturday, July 10, 2010

No ticket!

20

Saturday, July 10, 2010

Atoms exist!

• Like a bullet bouncing off a sheet of kleenex, a bit of a surprise.

• Coulomb showed atoms made of electrons & protons.

21

Saturday, July 10, 2010

But shouldn’t!

22

Saturday, July 10, 2010

Uncertainty principle

• Think about a musical note

• Short, high frequency, well defined position

• Pure tone has less well defined position

23

!5 5

!1.0

!0.5

0.5

1.0

Well-definedtime

Well-definedfrequency

Time & frequencyCANNOT

both be well-defined[that’s math!]

Saturday, July 10, 2010

Electron tries to get close, can’t

• If far from atom pulled in

• As it gets close is squeezed up

• But then momentum builds up

• And it races out

• Atom is a balance of these two pressures.

• No uncertainty, no us!

• That’s certain!24

Saturday, July 10, 2010

Double-slit experiment

25

How can you be in two places at once when you aren't anywhere at all? - Firesign Theater

Saturday, July 10, 2010

Double slit experiment

26

Saturday, July 10, 2010

27

Bullets & waves

Saturday, July 10, 2010

28

Double slit, in motion

Saturday, July 10, 2010

Single slit, in motion

29

Saturday, July 10, 2010

If you look, you destroy the interference

30

Saturday, July 10, 2010

Relativity vs The quantum

31

Niels BohrGuess who

• Smooth

• Localized

• Predictable

• But time is dynamic

• Quantized

• Fuzzy

• Uncertain

• But time is boring

Saturday, July 10, 2010

32

Relativity

Quantum mechanics

Time a bit fuzzy

Time an average over quantum fluctuations

None of the others

Blend

of re

lativi

ty

& qua

ntum

mecha

nics

Saturday, July 10, 2010

Gravitational radiation

33

Saturday, July 10, 2010

Loop quantum gravity

34

Saturday, July 10, 2010

Lindner’s double slit in time

Saturday, July 10, 2010

• New Theories of Everything, Barrows

• From eternity to here, Sean Carroll

• How to build a time machine, Davies

• Physics of the Impossible, Kaku

• Time Machines, Nahin

• Timeless Reality, Stenger

• Endless Universe, Steinhardt & Turok

• Black Holes & Time Warps, Thorne

• The New Time Travelers, Toomey

36

Saturday, July 10, 2010

37www.timeandquantummechanics.com

I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose. – J. B. S. Haldane

Saturday, July 10, 2010