(upbeat pop music)
- Good evening, everyone.
I guess, particularly with the topic,
it'll be important for us to start on time.
So, haha.
Well, welcome everyone to tonight's presentation
of the Daniel J Doyle Technology and Society
Colloquia Series, Manipulating time using science,
technology, and literature.
My name is Michael Reed and I'm the dean of the school
of science, humanities, and visual communications.
And I have the great privilege of introducing
tonight's presenter, Dr. David Richards.
David holds a PhD in instructional systems
from Penn State University.
A master of science and physics,
from the University of Alabama,
and a bachelor degree in physics
from Mary Washington College.
He is a full professor at Penn College
in the natural science department,
where he teaches physics, astronomy,
and spaceflight Courses.
Dr. Richards has taught at the college since 1995,
and has earned the innovative excellence in teaching,
learning, and technology award in 2005,
and an excellence in teaching award in 2007.
David is currently the principal investigator
of a 2014 national science foundation STEM
scholarship grant, and has received NSF research
fellowships at the University of Rochester's
and NASA's Marshall Spaceflight Center.
In addition, Richard serves as vice president
and president of the central Pennsylvania section
of the American Association of Physics Teachers,
receiving a distinguished service award in 2008,
and was a member of the national executive committee
for research and physics education.
David is beloved by students and has a passion
for learning and teaching.
David is an innovator and a collaborative leader
who is well respected within his department,
school, and college.
Ladies and gentlemen, please provide a warm welcome
for Dr. David Richards.
- Alright thank you Mike for that nice introduction.
Before we start, I'd just like to thank
the Penn College administration for hosting
this colloquium series, as well as a big
thank you for all of you making it out
for this evening's talk.
Now we can probably all agree that time
is our most precious, irreplaceable commodity.
But when we're asked to define time,
most of us have a very difficult time
coming up with a good definition.
So as a few of you were coming in this evening,
we handed out a little sheet of paper
with some pencils, and you wrote down
your definition of time, so let's take a look
at a few of these definitions.
(laughs)
I like that first one, right?
"Time to me is like a fluid we all move through,"
"the most valuable thing in the world,"
Some good quotes.
So as you can see there are a lot of ways
to describe and define time,
but what is it that we know about time?
So tonight's talk is going to look at two...
There we go.
So tonight's talk will look at the scientific
definition of time, as well as the technology
that we use to measure time,
and in the second part of tonight's talk,
we're going to look at how our mind
perceives time, as well as how we can use
literature and the written word to manipulate time.
So over the past century or so,
we've been using technology and science
to give us insight into what makes up the universe
and how old it is, so this image you see
right here, this is called the Hubble Deep Field Image
we're gonna look at in just a second.
It was taken back in the 1990's,
near the constellation Ursa Major,
the Big Dipper, and this patch of sky looks
void of nothing, there's just darkness,
and it's about the size of a pea
held at arms length if you close one eye,
and in the 1990's the Hubble Space Telescope
focused its cameras on that small patch of sky,
and it held it there for about two weeks,
opening the shutter and letting the light in,
and this is the image it sent back.
It's probably the most famous scientific image of all time.
And each dot and blob you see on that picture is a galaxy,
and each one of those galaxies
contains hundreds of billions if not trillions of stars.
A little while later in 2002 to about 2013,
the Hubble did it again, it focused its camera
and lens or mirror to a very small point in the sky
this is in the Southern Hemisphere near
the constellation Fornax.
And so you can kinda see this is called
the Extreme Deep Field, that little box right there,
and it took two million seconds of exposure time,
and this is the image it sent back,
and again this looks a lot like the image
the first time it took it,
and there's about 10,000 galaxies in this one image.
10,000 galaxies.
And again these aren't stars, but these are galaxies
that contain billions of stars.
So this Extreme Deep Field is the deepest image
of the sky ever taken.
It reveals the faintest and most distant
galaxies ever seen.
And this image allows us to explore further
back in time than ever before.
What you're actually looking at happened about 13.2
billion years ago, and we're just seeing it now.
So the light that left these galaxies
took about 13.2 billion years to reach
the detector in the Hubble.
Now scientists were able to use, called redshift,
to get the distances, and they put together
kind of a 3D map of those galaxies.
So those are the same galaxies,
but now you can kind of see it flying though it.
And again each one of these dots is a whole
galaxy of stars.
So physicists and astronomers have established
that our galaxy is about 13.7 billion years old.
That's 13.7 billion years.
That huge number is difficult for most of us
to comprehend, it's just too big.
So what if we condensed time from the beginning
of the universe until this moment into
one calendar earth year, what would that year
look like?
So here we have the big bang where space and time
were created, that would happen on January 1st
at midnight.
And then over the course of the next few months,
hydrogen is forming, clumping together form stars,
and fusing hydrogen into helium,
and then around May of that year,
our Milky Way galaxy starts to take shape,
and then over the next few months again
you have star formation,
stars go through a life cycle,
they fuse hydrogen to helium,
and big massive stars go though this process
and explode and seed the galaxy with heavier elements,
and eventually around September of this year
our solar system starts to take shape,
so you see our sun and the planets there,
and then over the next few months life starts to form,
and in December of that year,
we'll zoom in on that month because
it's a very busy month, as it is for most of us,
and you can see around December 25th,
dinosaurs appear on earth, and then they go extinct
around December 30th of that hypothetical year,
and what's interesting to note,
it's not until about two minutes before midnight
that modern humans appear on this timescale.
So we'll zoom in on the last 60 seconds of this year,
and you can see this is most of modern civilization.
And Columbus doesn't arrive in America
until about one second before midnight.
So even the scaled-down model is difficult
for us to process, so let's move to a timescale
that is a little bit easier for us to comprehend,
and that's the human lifetime.
So we can all relate to the human lifetime, right?
We can see how we age, and our ability to see
changes in our own outward appearance,
the wrinkles form and our hair turns grey.
The average human lifespan is about 70 years,
plus or minus, but it's about 70 years,
and during that lifetime your heart
will beat over 2 billion times,
and the red blood cells that are pumping in your veins,
and through your heart, they're being replaced
all the time, about every four months
those cells are being replaced by new cells,
and it turns out that within a seven year time period,
every atom in your body has been replaced
by different atoms, even your skeletal system.
So this means you're made up of atoms and molecules
that are different than the atoms and molecules
that you were born with.
We don't really create atoms,
we're just always recycling those atoms.
And really our memories are the threads
that link all versions of our material self together.
And we're going to be talking about memory
a little later this evening so.
So as I said we're going to talk a little bit
about the science behind time.
So a major role behind science is to careful analyze
innate ideas about how nature works, right?
So we know that there's, the earth spins on its axis
once in a day, and we're kinda dependent
upon the circadian rhythm.
So it's spins on its axis, it revolves around the sun,
and it gives us our day and our night and our seasons.
And then primitive timekeepers used sundials
to provide a simple means to quantify time,
but then in around 1602 Galileo Galilei
came up with a simple pendulum,
and this pendulum he designed determined,
it depends on the length,
the time it takes to oscillate back and forth
one full swing, is dependent upon its length.
So let me show you a quick demonstration.
This is a set of pendulums all at different lengths,
and I'm going to displace them, and let them go.
So you can see that they oscillate back and forth
at different times, and they form
a fairly interesting pattern,
and as you watch it, patterns will repeat themselves,
and they have to be set at certain lengths
to get these kind of patterns.
But you can see that a pendulum swinging back
and forth is a way to measure time.
The shorter the pendulum, the less time it takes
to swing back and forth,
the longer the pendulum, the longer it takes
to swing back and forth.
So as science and technology progressed, though,
we decided that we wanted to make time
a little more portable,
so we used escapements with springs and cogs,
and the pocketwatch was kinda developed
during this timeframe.
And then in the 1920s, the quartz crystal resonator
was developed, and the quartz crystal,
when you apply a voltage to it,
it vibrates at a very set frequency,
just as if I strike this tuning fork,
alright this is a 512 hertz frequency,
so when I strike this tuning fork,
the tines vibrate back and forth,
512 times per second,
that's what 512 hertz means,
it's vibrating back and it sets a certain frequency.
Now, that's kind of like what you see on the screen here.
That quartz crystal resonator, when a voltage is applied,
actually vibrates over 32,000 times per second.
So again this can allow us to measure time
to within a few thousandths of a second per day.
But this was kind of short lived technology,
because in the 1940s, the atomic clocks came into existence.
Atomic clocks use cesium atoms,
and they resonated at a very set frequency,
and we can use that to measure time to accuracy
within one billionth of a second per day.
One billionth of a second per day we can measure.
So at the microscopic level,
atoms and molecules vibrate at very predictable frequencies.
And a second was originally defined
in terms of a small fraction of our day
based on the Earth's rotation.
But now physicists define a second
in terms of the electron energy
transitions within the cesium 133 atom.
And I have a formal definition up here on the left,
but the thing you should see in that
is that it vibrates over 9 billion oscillations per second.
And the graphic that you see up here
shows over the last 700 years,
the early mechanical clock could measure time
with accuracy within a minute or so per day,
and then as the pendulum clocks developed,
the accuracy got better,
and you could measure to within a few hundredths,
and then when the quartz clock
was developed in the 20s,
you could measure to within a few thousandths of a second.
With atomic clocks, we can measure to much,
much higher precision, in fact the newer clocks
coming out can measure to one billionth of a billionth
of a second.
One billionth of a billionth of a second.
Which is pretty amazing.
And these clocks being developed are accurate
to within one second over a 10 billion year period.
So these clocks being developed
are only going to be off by one second
over a 10 billion year period.
So although our ability to measure time
will continue to improve,
nothing will change the fact that it is
the one thing we never have enough of, right?
So Alan Lightman is an MIT professor,
and he is a colloquial speaker from 2014,
and he wrote a book called Einstein's Dreams.
His novel fictionalizes Albert Einstein
as a young scientist who is troubled by dreams
as he works on his theory of special relativity.
Each dream looks at time from a different perspective,
and each chapter within the book
is a different world that reveals something
unique and interesting about time.
In one of the worlds he states,
"in a world where time cannot be measured,
there are no clocks, no calendars,
no definite appointments.
Events are triggered by other events, and not by time."
So as we have just discussed,
we can now measure time very precisely with atomic clocks.
However viewing an event in time
is different than measuring time.
Events that are triggered by other events
can be sequenced and viewed at different rates
using modern day technology.
So this technology has given us the ability
to take snapshots of events
that unfold over days or months,
or maybe even years, so that we can view
these changes in just a few seconds.
So up here you can see a few timelapse images,
these are star trails, so this is over the course
of a few hours during the nighttime,
and the camera, you can see it tracing out
the path of stars over the course of the night.
So this is taken over the course of a few hours.
This video shows a plant growing,
and again this is timelapse photography,
so you can see that growing
over a few weeks or months.
And up here you see Las Vegas development
from 1984 all the way to 2012,
you can see the sprawl of Las Vegas.
So the technology allows us to take
a large time period and contract it
into just a few seconds or minutes.
So technology has also given us the ability
to slow down events in time.
Let's get these started here.
As you watch these videos,
you can see that these are taking
a very small interval of time,
and spread out over a lot longer period of time.
So that's a balloon filled with oo-blick
being smashed by a ball,
and you can kinda see the outward spray.
A man being hit in the face with a balloon,
and an eagle coming towards us,
or sorry, an owl.
So anyway, we can slow down time,
and see things in a lot more detail.
Now this is an interesting video.
As you watch this video, the camera that took
this video is taking it at a trillion
frames per second, and it's showing a light pulse
moving through a bottle of water.
So that's a packet of photons
moving across the bottle of water.
Again this was taken with a high speed camera
that takes a trillion frames per second.
And being able to capture a pulse of light
moving through the bottle as if it were
going for a stroll across campus is really mindblowing.
The technology is really unbelievable.
In fact, this iconic image of a bullet
moving through an apple, if you were to take
a video of this bullet moving across that frame,
it would take over one year to watch using this same camera.
That's how slow it can slow down time, that technology.
So this video is pretty impressive.
Modern technology has really given us
some incredible insights into how
events unfold around us, but there is something
more amazing about nature that was discovered
a little over a century ago,
and that discovery was that the speed of light
is a constant of nature.
Alan Lightman again in his Einstein's Dreams novel,
he writes, "A world in which time is absolute
is a world of consolation.
For while the movements of people are unpredictable,
the movement of time is predictable.
While people can be doubted, time cannot be doubted."
And that's true, up until the early 1900s,
people assumed that time was a constant of nature,
was unchanging, was the same for everybody,
but if this were true then the world Dr. Lightman
describes here would exist and time
could not be doubted.
However, it turns out that time
is not a constant everywhere in the universe,
but that the speed of light is.
So the amazing thing about the universe
is that it doesn't treat time
as an absolute quantity, right?
It treats the speed of light the same, but not time.
So think about this, the speed of light
is the same for everyone, it does not change
with position or motion.
So as I turn on this flashlight,
if I could have a detector and measure
the beam of light leaving this lightbulb,
it'd move at about 186,000 miles per second
away from this source.
And if you measured it, you'd get the same speed
for that light.
We'd all get the same speed
for that light beam as I turn it on and off.
And that's about 300 million meters per second.
It's the fastest anything can move in this universe.
And even if I'm walking with this flashlight
and I turn it on, the speed of my motion
does not add to the speed of the light pulse.
So if I measure that speed,
I'll still get the same speed, so will you.
We always get the same speed for the speed of light.
And that's going to be an important topic
here in just a second.
So it was this revelation that the speed of light
is the same for everyone,
no matter how fast or slow you're moving,
that led Albert Einstein to discover
that the flow of time is not the same
everywhere in the universe.
So Einstein developed a series of though experiments
he called "gedanken" experiments,
and in these experiments, he played around with
time and he tried to figure out
exactly what it is that changes.
So he imagined two observers,
one at rest and one moving,
watching a light clock.
So I have a model of a light clock here.
So imagine these as two mirrors
and this is a beam of light
passing back and forth between the two mirrors,
(metal clinking rhythmically)
So imagine that as a pulse of light
just bouncing back as you saw in that,
moving across the bottle,
and that would keep a nice rhythm that could measure time.
So what we're going to do, is we're going to do
a little demonstration, so I have two
of my students coming up on stage here
to help me demonstrate this.
Nick and Reilly, could you please come up?
Okay.
So what we're going to do is I'm gonna turn on
this little ball here, okay,
and I'm gonna have Reilly, she's gonna be moving
the light pulse back and forth,
and the mirrors are going to be here, here,
and she's going to be bouncing that pulse of light
back and forth between the mirrors.
Now keep going, keep doing that,
so as you see it's going straight up
and straight down, there's nothing really
anything special about this,
but what we're going to do is,
we're going to put Reilly on a moving cart now,
so go ahead and sit down.
Okay, so Reilly's going to move the ball
up and down, just straight up and down,
and her reference frame is always
going to be straight up and straight down,
and as she's moving across the state,
I want you to take note of how it appears to move
from your perspective sitting there watching her.
Okay so, as she's moving across the stage,
you can see that the ball doesn't appear
to move straight up and down from your perspective
sitting there, you see it kind of go up
and then down, and then up and then down,
but it's going at an angle, like a triangle almost.
So even though Reilly's perspective
she sees it just going back and forth
and straight up and down,
you all sitting in your seats don't see
the same event, you don't see it the same way,
you see it moving at an angle,
almost like a triangle, as I can,
so as it starts there and goes up, down,
and up and down, so it's moving across the stage
as it's moving up and down.
Okay, so thank you Reilly and Nick.
They'll be coming back up on stage in a minute.
Thanks.
Okay so, what's the takeaway from all this?
So if we look at the light pulse,
as Reilly was standing up on the stage
moving it straight up and down
between the two mirrors, the distance traveled
is just this distance straight up and down.
But as Reilly was moving across the stage
as Nick was pushing her, you saw the beam kinda
moving across the stage like this,
and we're watching the same event occur, right?
You're just sitting still while she's moving,
but we're still watching the ball move up and down,
but we're not seeing the same type of thing happening.
Even though Reilly was sitting there on her chair,
she's moving with the light source,
so for her it's still just going straight up and down,
it wasn't moving at an angle relative to her,
just straight up straight down.
But for all of you, it didn't move straight up and down,
it moved at an angle, and this is an important
scientific discovery.
So Einstein used this idea,
so I'm going to explain a couple things real quick.
Speed times time is just distance.
If you're moving at 60 miles per hour down the highway
for two hours, you've gone 120 miles, right?
You just take the speed times time,
and you get a distance.
And distance is a length, so this length of this triangle
here can be written as the speed of light,
which is the symbol c, times time.
Now this time here is the time you would measure
if you had a watch on and you actually were
doing an experiment where you were watching
Reilly move across the stage,
that would be the time that you would measure
as you saw that light pulse move up and hit the mirror.
Reilly, though, this t with a little prime next to it,
that t prime, that's the time Reilly would actually measure,
because she sees the light pulse
go straight up and come straight down.
And then here, the v, that v is the speed
that Nick was pushing her across the stage,
that's the speed of the cart, right?
So there's a lot of symbols up here,
but in reality I just want you
to focus on the time here, the time of motion,
is this t, and then Reilly's time on the cart is t prime.
So if you remember Pythagorean's theorem,
this is just a simple right triangle,
so this side squared plus this side squared
should equal this side squared,
and that's what's written here.
And then if we rearrange the equation
to get t prime here on one side,
and all this other stuff on the other side,
just a little algebra, and you get an equation,
this is called Einstein's Time Dilation.
It's a pretty important equation,
so let's just look at what it means.
So v here is the speed of the cart,
and c is the speed of light.
Now Nick did a good job, but he wasn't moving
near the speed of light, he was moving fairly slow,
so this number here is very very small, tiny,
and the speed of light is huge,
186,000 miles per second,
so typically this number is almost zero
for our everyday experience,
we don't really notice much time differences.
So one line of zero is just one,
the square root of one is just one,
so the times were pretty much equal.
But as you get closer and closer
to the speed of light as you move faster and faster,
this value right here starts
to get a little more significant.
And what's this mean?
This mean's that Reilly's time,
that you see this t with a little prime here,
is different than the audience time,
and this was Einstein's huge discovery.
That time is different for people moving
than people that are standing still,
time is not the same for everybody,
it depends on motion.
So the faster you move through space,
the slower you move through time.
Alright so again the takeaway is it takes the light
longer for the moving clock you observe
than it does for Reilly's stationary clock
as she was moving with the clock,
so this means that moving clocks run slowly, right?
Time really did pass at a slower rate
for Reilly than it did for all of you here watching her.
So our time is very partial to us,
there's no such thing as an absolute time.
Time's not the same everywhere,
it does depend on your position and your motion.
In fact if Nick was able to push her
with an acceleration of about 1G,
so as I drop this ball, you know,
it accelerates, it speeds up as it falls.
If Nick had the capability of pushing her
with an acceleration of about 1G,
and was able to leave our earth and go out into space,
you gotta use your imagination here,
but if he could do that, and push her for about six years,
he'd reach very close to the speed of light,
about 99.9992% of the speed of light, right,
and in that six year period he would have traveled
about 250 light years away.
But now they're moving very fast,
so that they have to slow down,
so Nick pulled back on the cart and slowed down
at the same acceleration,
about 9.8 meters per second squared,
and they slowed down, they get to a distance
of about 500 light years, and it would take
about 12 years to go that distance.
And then if they repeated and came back to earth,
12 years out, 12 years back,
in their timeframe 24 years have passed,
but on Earth, over 1,000 years would have passed.
So it would be the year 3040.
So again it took them 24 years
to travel out and come back,
but everybody here would be long gone.
They've come back to an earth that was 1,000 years older.
So Einstein made us think differently
about what time is, and he created a whole
new perspective about how the universe works,
and today we use his equations
to correct for time differences
for very fast moving objects,
for example the GPS satellites in orbit around the Earth.
These GPS systems guide airplanes, cars,
and our cell phones, and they use atomic clocks
as we discussed earlier tonight
to correct for this time dilation.
There's a lot of physics going on,
time changes due to gravity and motion,
so for this example for GPS systems,
you have to take into account both the orbital speed
and gravity, but it turns out that GPS receivers,
even though they can locate your position
on Earth to within a few meters,
if you didn't take into account this time dilation,
they would be off by about 11 kilometers per day
and they would be useless as a tool.
So again you have to adjust atomic clocks
to compensate for that time difference
due to its motion and gravity.
Newer atomic clocks may even be more accurate,
and they can help pinpoint our locations
to within a few centimeters.
So in the future, self driving cars
are going to rely on this stuff,
so as atomic clocks get better and better,
and they go up on GPS systems,
our position on Earth will become better and better,
and the technology will utilize that.
Alright, so far this evening I've discussed
how we utilize science and technology
to control and manipulate events in time,
but what happens external to us may seem
much different than what happens inside of our brains.
So we're all going to do
a little experiment here in a second,
it's always good to do an experiment
during a science talk, right?
I'm going to invite Reilly and Nick
to come back on stage for just a second.
When you arrived this evening,
everyone should have received a time stick,
so it looks, on side it's an advertisement
for the clo-quee series, and some upcoming events,
but if you flip it over you'll see
there are some numbers written here,
and on the bottom it says "thumb line",
okay and if you didn't get one,
we're going to be working in groups here
in just a second, so I'm going to give this to Nick,
alright so they're going to demonstrate what to do,
and I have some instructions up here
on the screen so you can kinda follow here,
so hopefully you didn't bend your time stick
into a smaller thing.
So what you're going to do
is you're going to separate your fingers,
just a small gap here, now it doesn't have to be big,
and you want to place your thumb on the thumb line,
and when Nick's ready he's going to drop it
and not tell Reilly when he's going to drop,
so you don't wanna count and go "one, two, three, drop."
You're just going to drop it when he's ready,
and when Reilly sees this begin to fall,
she's going to react and close her fingers,
and when she catches it,
wherever her thumb is, there's a number there,
what is that, .21 seconds.
So this is, you're determining how much time
it takes for you to react to it.
So I'd like everybody to stand up,
you can stand up to do this,
it's a little bit better if you're standing,
alright, and go to the person next to you
and go ahead and try this, and then switch it up
and let the other person try it.
If you don't know the person next to you,
introduce yourself and go ahead and try this.
(crowd noise)
(laughs)
You need more coffee, yeah.
Yeah.
There's lots of cool things you can do with this.
Wow.
(laughs)
You know if you do it with peripheral vision it's faster,
so put it, look out that way,
and just look at, can you see it?
Turn your head like here--
(laughs)
You gotta get it just so it's right there,
you can barely see it.
(laughs)
Alright maybe not.
Alright thanks guys.
Alright.
Thanks for all participating, that was great,
againt your reaction time is around .2 seconds,
some people might be a little faster,
and I do this in my physics classes,
and usually it's between .15 to .25 seconds
depending on if you had coffee and so forth,
but it's a nice little experiment
to figure out reaction times.
So it does show us that there's a lag
between the beginning of an event
and the moment you can react to that event.
The brain is really a web of neurons
and chemical reactions and pulses going on,
and that controls your breathing,
your heartbeat, and most bodily functions.
So the time it just took you to react
to the dropping of the time stick
depended on the light hitting your retina,
where photons started this electrochemical reaction
that sent pulses to your central nervous system,
and again it takes time to generate this neural pattern
inside your brain, and it produces a map,
and that map has to be transformed
to your conscious thought,
and that has to produce a reaction.
So this leads us to the idea that our perception
of reality has less to do with what's happening around us
and more to do with what's happening up here in your brain.
Each type of sensory information
takes different amounts of time to process,
so our brain synchronizes all those pieces of information,
and creates a moving picture in our mind.
Again, our reality is ultimately constructed
in the dark by electrical pulses
moving between billions and billions of neurons
inside of our brain.
But how the brain assigns a time to every event
and then puts these events in chronological order
is really still a mystery.
And how we experience a perceived time,
it depends a lot, it varies lot, and it depends
on a lot of factors.
In fact, if you think about your relationship to time,
you'll probably find that time moves at a variable pace.
We all have days that zip by,
and nothing seems to get done,
other days so crammed with stuff
that about 16 hours feels like a week.
Remember when you were a child how time crawled
while you waited for your birthday,
or for some of you how waiting months
for the birth of your child
seemed like an eternity.
Or when you were in a life threatening situation
if you were ever in a car accident,
how the seconds seem like minutes.
And one of my books is Slaughterhouse Five
by Kurt Vonnegut, Jr.
In this book, a man by the name of Billy Pilgrim
becomes unstuck in time.
He jumps around in time and space
from his life as an optometrist in alien New York
to a prisoner of war in Dresden, Germany
during World War Two, to even a zoo
on the planet Tralfalmador, where he walks around naked
inside a model home under a glass dome
as part of one of the exhibits on the alien world.
One quote from the book is that, "the time would not pass.
Somebody was playing with the clocks,
and not only the electronic clocks
but the wind-up kind too.
The second hand on my watch would twitch once,
and a year would pass, and then it would twitch again.
There was nothing I could do about it.
As an Earthling I had to believe whatever clocks said,
and calendars."
As Earthlings we do have external tools
for helping us to chronologically organize our time
like our clocks and our calendars,
but how we and Billy Pilgrim perceive time
does not always correlate
with what the clocks and calendars state.
So I have a few pictures here from a man
by the name of Jeb Corless.
He's a wing suit flyer, and one day a few years ago
he had a near death experience.
During one of his flights, he misjudged a balloon
that he was aiming for, and he hit a rock
at about 120 miles per hour,
and you can kinda see this image here,
that's him hitting the rock.
Now when he hit this rock, he kinda went out of control,
he was still in a free fall state,
and I'll show this video of him doing this here in a second.
He broke both of his legs and his ankles
after hitting this rock, you'll see here in a second.
So that's the balloon he was aiming for,
but he came in a little too low.
And you can see as he's free falling here,
it only took a few seconds before he got to the ground,
but as he continued to fall he said to himself,
he was having a conversation with himself,
and he said his brain kinda split
into two different thought patterns.
One was, should I pull my chute and hit the ground,
and die an agonizing death and bleed out,
or should I not pull my chute
and just fall and let it be over instantly.
And he said that at that time
as he was thinking about this and reasoning through
it felt like minutes had passed,
but going back at the video it was only four seconds,
before he actually grabbed his chute and pulled it out.
So what seemed like minutes of rationalizing
in his brain turned out to be just a few seconds.
So does time really slow down in these traumatic events?
David Egleman, he's a neuroscientist
at Stanford university, and he developed a method
to test if the brain can actually slow down time,
because he had a similar incident
when he was a child falling off a ladder.
So he designed an experiment,
as you'll see on the top right here,
he developed this thing called a perceptual chronometer,
and this'll loop through a couple times
so you can see it, and these people are being dropped
from 150 feet into a net,
they're being dropped backwards,
so this perceptual chronometer here if flashing
and they're flashing numbers,
so if you look at the bottom screen here,
they're block numbers, and they're LED,
so this is a four, so it'd be a red four,
and there'd be a black four and so forth.
And if you get the frequency of the flash just right,
the eye can't pick out the number,
it just looks like this, right?
So on the ground they would get it flashing
just at the right rate so that your eye
could not pick out the number,
and then as they were being dropped,
they were watching their little wristwatch, so to speak,
and watching the time, or watching their digital
chronometer here, and they were trying
to see if they could see those numbers.
But it turns out that there was no difference
between one's inflight performance
versus their ground based performance.
Time doesn't really slow down
when you're in this freefall or excited state,
it just seems like it slows down.
But many of us were sure that when we were in an event
at some point in our lives,
time slowed down for us,
but it's really a retrospective assessment
of that memory.
When you go back and think about it,
your brain does something pretty miraculous.
So again people don't actually see time
in slow motion during events like this,
instead it's a retrospective assessment of the memory,
so our perception of the flow of time has been changed.
But even in non-life-threatening situations
our minds can be manipulated
to slow down or speed up time,
but that's through other means,
and that means is through the written word.
So writers get to play with time.
A skilled author is able to shrink or stretch time,
compressing an entire decade into a single paragraph,
or spreading a single moment over an entire chapter.
That's the wonderful thing about writers
and getting to read their work.
So one of those stories I read as a kid
was called The Occurrence at Al Creek Bridge.
And I don't know if some of you
might have read this story,
it's also known as A Dead Man's Dream,
it's by Ambrose Bierce.
And the story takes place during the Civil War,
and the main character's name in it is Peyton Farquar.
And he's about to be executed by hanging
from an Alabama railroad bridge.
And he was being hung because
he was trying to burn down the bridge,
and the Union soldiers captured him.
So as they dropped him, the noose around his neck breaks,
and he splashes down into the water below,
and his senses become enhanced,
and he flees and travels all night,
30 miles back to his home,
and as he makes it through the gates
and goes to embrace his wife,
he feels a heavy blow to the back of his neck,
and it turns out that Peyton never did escape,
he imagined the entire story
in the split second that it took
to fall off the bridge, and for the noose to break his neck.
And I read this in middle school,
but I remember that twist at the end of the story
shook me in a way that made me uncertain
about one's own perception about time,
and how we perceive time.
So simple black and white text on a page
has the power to transport you back or forward
through time over vast distances of space,
just like Billy Pilgrim in Slaughterhouse Five, right?
Billy Pilgrim's encounter with the Tralfalmadorians
also made him think differently about time.
He talks about these aliens,
and he says that they were able
to look at all moments of time,
the past, the present, and the future all at once.
To them, when a person dies,
he or she only appears to die.
They are still very much alive in the past.
These aliens explain that every moment in time
has always existed, and always will exist,
it's just an illusion here on Earth
that once a moment is gone, it's gone forever.
But is it gone forever,
or is that just our collective perception?
Now I've mentioned Einstein's Dreams a couple times tonight
and again that's one of my favorite books,
but in Einstein's Dreams, it's a book that truly
demonstrates the personal relationships
each person has to time.
Dr. Langman is able to manipulate time
in so many thought-provoking ways.
So I'm going to read just a quick excerpt
from this book, this is the third of June, 1905.
"Imagine a world where people live just one day.
Either the rate of heartbeats and breathing
are speeded up so that an entire lifetime
is compressed to the space of turn
of the Earth on its axis,
or the rotation of the Earth is slowed
to such a low gear that one complete revolution
occupies a whole human lifetime.
Either interpretation is valid,
in either case, a man or woman sees
one sunrise, one sunset.
In this world, no one lives
to witness the change of the seasons.
A person born in December in any European country
never sees the hyacinth, the lily, the astor,
the cyclamin, the edelweiss.
Never sees the leaves of a maple turn red and gold,
never hears the crickets or the warblers.
A person born in December lives his life cold.
Likewise a person born in July
never feels a snowflake on her cheek,
never sees the crystal on a frozen lake,
never hears the squeak of boots on a fresh snow.
A person born in July lives her life warm,
the variety of seasons is learned about in books.
In this world a life is planned by light.
A person born by sunset
spends the first half of his life in nighttime,
learns indoor trades like weaving and watchmaking,
reads a great deal, becomes an intellectual,
eats too much, is frightened of the vast dark outdoors,
and cultivates shadows.
A person born at sunrise learns outdoor occupations
like farming and masonry.
Becomes physically fit, avoids books and mental projects,
is sunny and confident, is afraid of nothing.
So both sunset and sunrise babies
flounder when the light changes.
When sunrise comes, those born at sunset
are overwhelmed by the sudden sight
of trees and oceans and mountains.
They are blinded by daylight.
When sunset comes, those born at sunrise
wail at the disappearance of birds in the sky,
the layered shades of blue in the sea,
the hypnotic movement of the clouds,
they wail and refuse to learn the dark crafts indoors,
lie on the ground and look up,
and struggle to see what they once saw.
In this world in which a human lifespan is but a single day,
people heed time like cats
straining to hear sounds in the attic,
for there is no time to lose.
Birth, schooling, love affairs,
marriage, profession, old age,
must all be fit within one transit of the sun,
one modulation of light.
When people pass on the street,
they tip their hats and hurry on.
When people meet at houses,
they politely inquire of each others' health,
and then attend to their own affairs.
When people gather at cafes,
they nervously study the shifting of shadows,
do not sit long.
Time is too precious.
A life is a moment in season,
life is one snowfall, a life is one autumn day."
And this is just one example of how
Al Lightman so brilliantly manipulates
our perception of time.
So to conclude tonight, hopefully as you leave here
you have a sense of how science and technology
can define measurements and moments in time,
and also realize that time is a subjective
and abstract concept, it's still not really understood.
Many authors out there right now that are still publishing
about what time really is.
You also got a demonstration of relativity theory,
and how it shows us that time
is not an absolute quantity, right?
It depends on your motion and your reference frame
if you're sitting in the audience
or moving across the stage like Reilly did.
Also time is constructed in our minds
and can be manipulated to recall certain memories,
and also with literature.
But our sense of time is often dictated
by how much information we process,
so new stimuli can appear to slow down time.
So the more dense and detailed the memory,
the longer the moment seems to last.
So keep learning, visit new places,
meet new people, and do new things.
And just maybe, you'll find you've lived
a longer and more fulfilled life
Thank you.
(audience applauding)
- Time, this is your time to ask Dr. Richards
your questions.
We have some microphones throughout the audience,
so if you just want to place your hand
and someone can get you a microphone
to ask Dr. Richards questions.
- Hey Dr. Richards.
- [Dr. Richards] Hello.
- Have you ever seen Stephen Hawking's
speech on time on TV about the speed of light,
if we could get a train going at the speed of light,
and then the girl running on the train
relative to us would be faster than the speed of light
but relative to the train
would just be running on the train?
- Again, that's not quite accurate,
because it's relative motion.
She'll never travel faster than the speed of light.
Is that your question?
- [Student] Yeah. I just like wanted your thoughts on that,
because I was like oh snap,
she could run faster than the speed of light,
she runs.
- Yeah.
So it's a good thought experiment,
but it turns out that no matter how fast she runs,
she'll never reach the speed of light.
She'll can approach the speed of light,
but she'll never reach the speed of light.
And there's a couple things happening here.
When you're dealing with relativity,
not only does time dilate,
but length also contracts,
so it depends on your, if you're watching,
if I'm the girl running, I'm moving across the stage here,
but imagine me on a train and I'm running with the train,
and the train's moving at 99.999% the speed of light,
and then I start running forward,
so you think, well my little additional velocity
is going to increase my speed above the speed of light.
But in reality, that's not what happens.
It turns out there are a lot of laws of physics
that get violated if you try to hit the speed of light.
And you need about an infinite amount of energy
to get any mass to reach the speed of light.
You can get really close to it,
but you're never going to reach the speed of light.
So what happens from your perspective,
watching this girl, you're gonna see the train
start to shrink in length,
and the times aren't that you measured,
just like we did up here,
it's going to be different
than the times that they measured.
But the girl will never exceed the speed of light,
just like the train can't exceed the speed of light, so.
I don't know if I've answered your question,
but I haven't seen that exact...
Okay.
Okay.
(laughs)
Alright so good, so Stephen Hawking agrees with me.
(audience laughing)
- [Student] Hello there.
- Hello.
- Do you know of Miguel Alcubierre's
theoretical faster-than-light drive?
His theory of how one could go faster than light?
- I'm sorry what was the guy's name?
- [Student] Miguel Alcubierre.
He theorized that if one were to use
a form of exotic matter, one could contract
spacetime in front of a vessel
and expand it behind the vessel,
and it wouldn't actually be interacting
with spacetime, more parting it,
such that the vessel would not be interacting
with the vessel.
- Well yeah if you can create enough
mass or energy to warp spacetime,
technically you could move faster
than the speed of light
if you were actually warping that spacetime.
So yeah, in physics and in mathematics,
there's nothing that theoretically says
you can't travel faster than the speed of light.
But in practicality, and when you look
at the science behind it,
the ability to create that much mass and energy
is very difficult, like you said exotic matter,
being able to create this huge mass
and warp spacetime enough around you
that you could go faster than the speed of light.
So can it happen in the future?
I'm never gonna say no, because we're always
being proved wrong, but at this point in time,
a lot of those are just theories, right?
Hypothetical.
- [Student] I just have a question about if we change
direction in a space, would we change the way
that time is measured.
Like if as the Earth orbits around the sun,
we're moving forward through time,
but if we reverse the motion,
are we still moving forward in time?
- Sure.
Yeah, the direction of motion's not going to affect
your time (mumbles), so your time's still the same.
Now if you could, like in the Superman movies
and all that where he pushes the Earth
and goes back in time, again to travel forward
or backwards in time, it's very tricky.
Obviously you have to be able to move
at very fast speeds to go forward in time,
but you're still moving forward in time,
you're just not moving forward in time
the same rate as somebody outside your frame of reference.
And in your little reference frame,
you don't really notice anything different.
We could all right now be moving
at 99.99% the speed of light,
but we think we're at rest.
There's nothing we can do in this space right here
to show that we're moving a that speed.
It's called an inertial frame of reference,
we're all in the same frame right now.
So we could be moving at 20 miles per hour
or 99% the speed of light,
and I could do an experiment up here,
and we'd all get the same result,
so we'd all agree on it, there's nothing to discern
how fast you're moving relative to somebody
outside of you, right?
It's when you compare reference frames
that's where things get tricky.
When you compare your clock to somebody else's clock
outside of your little lab,
and then times start to shift.
But it's a real event, like I showed you,
GPS systems have to correct for this time dilation,
and there's been many experiments over time
that have shown that this time dilation's a real thing.
So time is relative to motion and to gravity.
Yeah.
Okay.
- A second is defined
as like nine billion and some vibrations
of a cesium atom.
- [Dr. Richards] Right.
- So what's a second?
Why did they choose nine billion so many vibrations
of the cesium atom, someplace there was a definition
of what is a second before they did that--
- [Dr. Richards] Sure.
- So what is a second?
- Well, it goes back to the day.
So it goes back to astronomical observations, right?
So originally a second was defined
as one 86,000ths of the time takes
for the Earth to spin on its axis,
but when you deal with astronomical observations
and the spinning of the Earth,
and comparing it to stars out there,
that's how we did it for millennia,
but it's not as accurate, because there's always
perturbations and little things that aren't
quite the same, and so the idea is how
can we define time, and there's a system,
an international system that agrees on this.
Like what is a one kilogram mass?
And what is a second?
Alright, so we have to come up with some standard,
a standard is a fixed and reproducible thing
that we can all agree on,
and so again a second comes back down
to the Earth's rotation in our day,
24 hours in a day and broken down,
and then we just take that one second time interval,
and we split that up into smaller segments,
to like a billionth of a second.
But you're right, you have to define second somehow,
and it goes back to our original definition of time
in terms of the 24 hour period of the Earth's rotation.
So we break it down into 24 hour periods,
and that's broken down to 60 minutes,
and that's broken down to 60 seconds,
and so forth.
Yeah we are closer to the sun in the winter months,
but really once, we kinda have a new standard,
we said "alright, this number of oscillations per second
matches", and so we kinda got away from the standard
of the astronomical and the Earth's spin,
and define it in terms of vibrations or frequencies
of that atomic atom, so again you have to choose
a standard to define time,
so this was 1967 that they came up
with that formal definition of how many vibrations
of a cesium electron in the outer shell.
But again, yeah you're right, you have to have some basis,
what do you define one second as?
Then it goes back to the Earth's rotation,
yeah it varies with time like you said.
- [Host] We have time for one more question.
- The time stick?
Okay yeah, so time stick that you used
to figure out your reaction time,
I do this in my physics classes,
and usually you use a ruler,
and so there's things called kinematic equations
that describe all kinds of motion,
and so y equals one half,
well I'm not going to go through all the equations,
but basically what I did was I figured out
the distance that it'll fall
in each fraction of a second,
so you notice those aren't equally spaced?
If you look at those little lines on that time stick,
there's different spaces between those lines,
and that's because as its falling it's accelerating,
so it's covering more and more distance as it falls, right?
So when I sent that over to du-pan,
I said this is how many pixels you need
to have between each line in order to get that
to correlate to a falling time, right?
So it's a good experiment, if you take a dollar bill
with some friends, have em put it in the middle
of a dollar bill, and bet them that they can't catch it.
There's no way they're going
to be able to react fast enough,
and tell 'em if they close their fingers,
they owe you a dollar, right?
If they try to guess when you're gonna drop it,
you'll win every time, you'll make a lot of money.
(laughs)
- [Host] Alright.
Again I want to thank, if you'll join me in thanking
Dr. Richards, and I want to thank the audience too--
(applause)
I know there's still a few questions from the audience
which is wonderful, and Dr. Richards will also
be available downstairs after this,
and there's some refreshments for further discussion
down at Rapture down below following this session,
so Dr. David Richards will also be downstairs for there.
And I also want to remind you all in February seventh
is our next presentation by Dr. Robert McColley,
and his presentation is entitled
"A General Assertion is Worth Innumerable Pictures",
so again if you could mark your calendar
for February seventh and we hope to see you back here.
Again Dr. Richards, thank you so much.
(applause)
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