120th Meeting
Speaker’s Night
Day:
Speaker: Dan Falk
In Search of Time
Dan Falk author of the book “In Search of Time” spoke
about time. Long ago, Augustine said
that he knows what time is until he has to explain it. Aristotle noted that
time goes by. Our earliest ancestors,
being hunters, had to be aware of time noting the cycles of sunrise and sunset,
moonrise and seasons. Animal bones with
notches in rows from
We have been keeping track of time with ever better
precision. Sundials and mechanical
clocks measure what happens in the sky. There became a natural tendency to deal
with time abstractly. We then think that time moves along independently of
anything else. Sir Isaac Newton, in his Principia Mathematica (1687), wrote
that there is a true, absolute time flowing uniformly without reference to
anything else and gave a definition of “mathematical time” vs “common time” as
measured by a clock (which is not perfect).
The Sun moves non-uniformly because of Earth’s elliptical orbit. Thus
sundials are not perfect. According to
Albert Einstein published his theory of special
relativity in 1905, and general relativity in 1915. The implications of his theories are that
time and space are linked, that time measurements depend on speed and that
gravity distorts spacetime. Einstein did
thought experiments describing the experience of an observer moving rapidly and
that of one who is stationary – each observer sees things differently. There is no absolute tic-tok everywhere in
the world. The universe is not static and it may have had a beginning. He
introduced the cosmologic constant to make the universe look static. But, what came before the Big Bang? The answer is that there is no time before
the Big bang just as there is no north, north of the North Pole. Time is not defined and it emerges from
something such as a particle, or there was an epoch prior to the Big Bang. Andre Linde in the 1980’s postulated that
there is eternal inflation going on all the time or colliding “branes” that
release energy causing recurrent big bangs.
Is time travel possible? We need to distinguish between travel into
the future and into the past. Time
travel into the future is not controversial.
One needs to accelerate quickly – as an example, on the space station in
orbit around the Earth. Time travel onto
the past could be facilitated by curved spacetime of general relativity. With a severe curvature of spacetime, travel
into the past might be possible. Dan
described the grandfather paradox (someone going into the past, killing his
grandfather and not being born) and suggested three possible solutions: 1) time
travel into the past is impossible, 2) time travel is possible but you can’t
change the past, 3) parallel universes and parallel timelines may allow many
possible scenarios, a supposition supported by quantum theory and membrane
theory.
Could the flow of time be an illusion? Julian Barbour, physicist, denies that time
flows and says that there are many “nows” with no “flow’ connecting them. He says that time is a mistake. D.C. Williams, philosopher, (1899 – 1983)
said that time flows only in the sense that a fence recedes. But if time is an
illusion, what sort of illusion could it be?
Or perhaps, as physicist Lee Smolin says, we have made a profound
mistake and we need to unfreeze time and represent time without space.
Chris Malicki, Secretary