1. Lying just beneath everyday reality
is a breath taking world where much of what we perceive about the universe is
wrong. (0 to 9 sec of intro)
2. The 3d world is merely a mirage
(intro of show)
3. But time is not what it seems. There
may be no distinction between the past, present, and future (intro)
4. Discoveries over the last century
have shown that much of what we think about time may be nothing more than an
illusion. Contrary to everyday experience, time may not flow at all. Our past
may not be gone, our future may already exist. Time itself can speed up or slow
down. Events we think can only unfold in one direction can also unfold in
reverse. (2:45)
5. Use of day and night for time
(sundial), to full rotation of earth around the sun, pendulum, to vibration of
a quartz crystal (looking for a repetitious cycle), to use of vibration of
atoms to use as a clock (vibration of a cesium atom). Clocks can tell us what
time it is but what time is.
6. What time is exactly is unclear but
the passage of time is very familiar to us.
7. Rise of train travel led to startling
discoveries about time: each town had their own time and trains would carry
time of the city where the train started. Need for synchronized clocks arose.
Time for Issac Newton ticks at the same rate for everyone. As sensible as it
may seem, Einstein found that time could
run at different rates. Time for me may not be the same as time for you. Time is experienced individually. No
universal tick tock. There were times. Einstein found the link between the motion through space and the passage of
time. The more you have of one, the
less you have of the other. Time and space is linked in much the same way
that north and west are. When you are
still and not moving through space, all of your passage is through time, but as
soon as you start moving through space, some of that previous passage through
time has to be diverted and shared with your motion through space resulting in
a slower passage through time. Time itself is moving slower for the person
that is moving.
8. At the slow speeds that we move here
on earth, motion’s impact on time is too tiny for us to experience it. The
effect is real though and can be measured with the use of two atomic clocks and
a jet airplane. This experiment carried out in 1971.
9. Space and time can no longer be considered separate things. Space-time
10. This idea of space-time led Einstein
to realize that this sharp difference we see between past, present, and future may only be an illusion. In our day to
day lives we experience time as a continuous flow but it may also be helpful to
think of time as a series of snapshots. It is the unfolding of moment, after
moment, after moment. Imagine all snapshots lined up. Every moment here on
earth as snapshots lined up. Think of
all the snapshots that ever happened and will happen as a loaf of bread. My
moment of now may seem to include a cat jumping off the couch, the clock
ticking exactly at 12 PM, a pigeon taking off, and a meteor striking the moon.
But Einstein said that this now slice would be cut a different angle should we
be moving through space. Because motion affects the passage of time, someone
who is moving will have a different conception of their “now slice” because it
would be cut at a different angle.
11. Even if the movement is considered
slow, because of the vast differences in space, our conception of now can vary
by massive amounts in time. The
direction makes a difference too. If the alien is biking towards earth the
angle will be angled towards the future. “Once
we know that your now can be what I consider the past or your now can be what I
consider to be the future, and your now is every bit as valid and my now, then
we learn that the past must be real, the future must be real, they could be
your now. That means past, present, and future are all equally real. They all
exist.” There is just as much reality to the past as there is to this
present moment. Just as we think of all of space being out there, we should
think of all of time being out there. All that has happened and all that will
happen, it all exists. This realization convinced Einstein that the distinction
between past, present, and future is only an illusion, however persistent. There is nothing in the laws of physics
that picks out one now over another now. It is just our own subjective
experience that it feels like things are changing.
12. The arrow of time. This is not true with
space- we can go back and forth. What can’t time do this? Why don’t we see
things flow in reverse order? There is nothing in the laws of physics, that
states that events have to flow through what we call “forward” in time. Most
equations work equally well for moving forward and backward in time. No arrow
of time attached to these equations. Contradiction between physics that seems
reversible and so much of our lives that seems irreversible. What’s responsible
for the arrow of time?
13. Entropy. The arrow of time seems to
come from the tendency of nature to move towards disorder. “a measure of
disorder tends to increase with the passage of time and that propulsion seems
to create an arc of time” One problem with this reasoning though. Because the
laws of physics don’t distinguish between the future and the past, entropy
should increase towards the future but also the past, and that makes no sense.
“that’s like saying entropy should increase in either direction that we look.
We should look backwards in time and it should increase. “We should look
forward in time and it should increase.” The big bang set the arrow of time on
its path. Universe started out in a very ordered state and is ultimately
responsible for the fact that time seems to have a direction.
14. Because the expansion of our universe is
accelerating, in the far future, after 100 billion years or so, all of the other
distant galaxies will have hurdled out of sight from us. It will appear as if
our galaxy were in the middle of nothing. Light from distant galaxies have to
travel so far to reach us that when we look out at them, we actually are
looking back in time. So in the far future where the distant galaxies are no
longer visible, astronomers will find the past, in cosmic terms is out of
reach. And as for the end of time, one theory says that black holes will
eventually dominate the cosmos. Then they too will evaporate leaving nothing
but random particles drifting through space. “In the far future where
everything has decayed and there is no change, there will be clear notion of
the past or the passage of time.” “if you don’t have events happening, then
it’s hard to see how you would even imagine that there was time.” “you can’t
even tell which direction of time is forward or backwards. In a very real
sense, time one day will lose its meaningless.”
15. “In comparing our everyday experience
of time with the true nature of time, we’ve been forced to challenge some of
our most deeply held beliefs. We now know that for every event that goes from
order to disorder, there’s a link to the big bang itself, giving us the arrow
of time. The common sense notion that one true time governs the universe has
given way to a picture in which time is different for each and every one of us,
and the flow of time, which seems to us as real as the flow of a river, may be
nothing more than an illusion. Past, present, and future may all exist on equal
footings. Our everyday experience of time will always exert a powerful
influence. We will continue to imagine that time is universal, that the past is
gone, that the future is yet to be, but because of our scientific discoveries,
we can also look beyond experience and recognize that we are part of a far
richer and stranger reality.”
Key Points:
-
There is no distinction between the past,
present, and future. They all exist and there is no precedence for one moment
in time over another.
-
There is no one, universal time that governs the
lives of all of us. We all have our own slices of now. Each and every one of us
experience time separately because motion slows the passage of time and
although with the speeds humans can achieve, this effect is not noticeable, it
is real and over vast distances in space, motion through space can have a vast
impact in time and gives us our own individual now slices.
-
There seems to be an arrow of time in our lives
that results from an increase in entropy that started since the big bang, even
though no laws in physics says that events cannot unfold in reverse order.
No comments:
Post a Comment