Manipulating Time Using Science, Technology & Literature

Manipulating Time Using Science, Technology & Literature


(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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