[No Dialogue}
>> Dr. Wahby: Well, good
afternoon, and you can't find a
better day with sunny
skies in November.
Believe it or not it is the
first day of November, and we
are thankful for the good
weather, and our thoughts go out
for Sandy people who, on
the other side of the continent
where they have some troubles,
so we just count our blessings
here, and pray for them, and
keep them in our thoughts.
Welcome to this session, special
session of this symposium,
"A Futuristic Look
through Ancient Lenses."
Now if you are in a class with
Mr. Linton, you are obliged to
look into the skies, kind of,
because this is your work, your
study, your specialty, but guess
what, we the 21st century guys
and girls mostly lost the glory
of looking into the skies and
have all sorts of to just
go and float like this.
I wish many more would do this
and look at moon, look at the
stars, and so forth.
Well, before I introduce our
distinguished speaker today, I
want to thank John Looby and
give him a hand please.
[Applause] Now if you see
microphones and media services
and other, usually you don't see
the people behind the screens,
and the curtains, we want to
acknowledge him and Arlene here
will give him this Certificate
of Appreciation, working behind
the scenes, but always seen.
[Applause] Thank you.
Another thank you goes to Bev
Cruse.
She faithfully documents in
picture, artistic picture all
the symposium and other stuff,
you have seen here, maybe in
your graduation
you'll see her also.
She'll take your photo.
Thanks, Bev.
Thanks to Wes also,
documenting in video.
So thanks to all the media.
Please give them a hand.
[Applause] Without this,
we couldn't document.
Well, he tries to bring
the skies down to earth.
And he is a down
to earth person.
I mean I have never seen such a
pleasant person to talk to, and
discuss things, and work with,
over emails for a long time, and
then when I met the person,
it was pleasant surprise.
So thank you very much
for accepting to come
and speak with us.
>> David Linton:
Thank you Wafeek.
So should I start?
>> Dr. Wahby: It's all yours!
Very good.
>> David: Thank you.
Well, let's get going.
I've got a title slide here
with me, and a couple graphics.
A year ago the title
was "Bringing the
Sky Down to Earth".
That was Egyptian Astronomy.
Here we are doing it a
little bit differently.
Astronomy in Ancient Greece,
that's not where it started, and
that's not where we begin seeing
astronomy but I think that's
where it became a science.
Or maybe not exactly a science,
as we define it today, there
weren't all the elements of
science going on then, but many
aspects were created,
invented in ancient Greece.
On the right, excuse me, left
side of the screen, you have a
depiction of the
Pythagorean Universe.
The central fire, the hearth of
the universe, the home of Zeus,
it's been called all of those,
I will talk about that
a bit later.
We can't see it, because there
is a counter earth there between
us and the central fire.
That was one of the models.
Hipparchus, that is a person
that I have not spoken of in the
astronomy class, classes this
semester is probably regarded as
the greatest
astronomer of Antiquity.
You'll hear some about him yet
later in this semester, those of
you who are in my class.
You see him there actually
observing an instrument known as
a quadrant or astrolabe
perhaps, measuring perhaps
the altitude of a star.
Perhaps measuring
something else in the sky.
So, Greece is a long ways away,
so on our way to Greece, let's
stop off in Florence and we
did so two years ago.
I didn't know in advance that
you were going to be doing this,
but met my namesake, hob nobbed
with some ancient astronomers.
And had a feeling as I've looked
back through my slides, I've had
a feeling that maybe I
really was in Greece.
There was a statuary, there was
just gorgeous statues, Pegasus,
the winged horse, I've had one
group out that I've had a chance
to show that to, that star
pattern at least, not the flying
horse itself, you have to use
your imagination that that's
what it outlines in the sky.
But there it is, nice sculpture.
And if you look carefully, right
up here, you'll see a baby
flying off in the distance.
Baby winged horse.
There was also
Poseidon, in Florence,
and what else did we have?
[Unclear dialogue] Bronze of
Perseus and the head of Medusa.
And we have Perseus the warrior
in the sky close to Cassiopeia.
And also Two-End
Dramada, and Pegasus.
Reminders of the Trojan War.
That was probably
fought somewhere, Lee,
can you give me a date?
Maybe 1200 BC, 
>> Lee: There was no actual
Trojan War.
>> David Linton: There was
no actual Trojan War?
I read Homers.
Circa 1200.
Ok, but certainly reminders, I
thought that was evidence in
behalf of that.
After Florence, moving a little
closer to Greece I went to the
other side of Italy, and on the
Grand Canal, in Venice, looking
over at St. Mark's Cathedral.
The Cathedral right here this
building the bell tower, and
we'll go up that, it's quite
a view from up there,
go up there in a moment.
You have this building that we
are going to take a much closer
look at here shortly.
This is a building with, well, a
clock in it, very special clock,
that we'll take a look at.
Let's go to the top, and
when we go to the top,
we find Galileo again.
He has been here, and he has
been there, well, it was 2010
when I was there, so just over
400 years ago, it was August 21,
that he was there,
and what was he doing?
He was showing off the new
telescope, the telescope that he
had built, to the
leader of Venice.
And he was trying to sell it.
And sell himself as the
maker of the telescope.
He did not invent the telescope,
he heard about it and with the
glassworks near Venice, on
Murano Island, he was able to
get glass ground to his
specifications and to make
telescopes, he made some
money doing that, he got some
influence and a
great reputation.
1609, August, and what
would you use a telescope
from up there for?
It's not looking
very high in the sky.
In fact, I don't think he should
really be looking up at all.
Because when you look out, you
are looking down at the red tile
roofs of Venice, and off in the
distance, if you look in the
right direction, you are looking
towards the Adriatic Sea, maybe
there are some enemy ships
coming in, you can see those,
you can use this for defense,
or early warning device.
And that could be what it was
used for, what he was trying to
sell it for in August.
But things changed in
the next few months.
Now, look again, at this
building that I called your
attention to before.
This building houses a clock
right here and a couple of
probably bronze folks on the
roof there to ring a bell.
But my attention was drawn to
the clock, and I went down
there, and looked up
from ground level,
and the clock is really
very beautiful.
It was constructed 110 years
before Galileo showed his
telescope to the doge.
It was finished
110 years earlier.
And looking carefully at the
ground level, you can see some
signs in the windows.
We take our culture, our own
culture around the world as
well, it has spread, there
borrowed Americano in those two
windows down there.
Up close, what you see is
something again from Greece.
This is the culmination,
represented there, the
culmination of science of
astronomy science the best
science in ancient Greece.
Put together in about
140 AD I believe.
This is a 24-hour clock.
Of course the numbers in Roman
numerals around the edge.
And the pointer, there's only
one pointer, not a minute hand,
just a hand, I guess a pointer,
and that's towards
the number 16.
It is 16:00, which I guess
we should say, 4:00
in the afternoon.
And that is the sun in the sky.
In the center is
an immobile earth.
The earth is not moving.
It is stationary.
And this was the cosmos.
This was the universe
to the Greeks.
Not to all, but to most, and by
the end of the run of science in
Greece, with Claudius Ptolemy,
in about 140 AD, he put together
this model in its best form.
Earth in the middle, we've got
the moon here, not in the same
direction as the sun, off a
little bit to the left, it's
phase is shown as a
thin crescent.
We've got what here, along the
peripheral, the edge, inside of
the hours, what is that?
Constellations of the Zodiac.
It's the constellations through
which the sun moves in the
course of the year.
And if you watch this, maybe you
look at it again, after taking a
gondola ride, which we did, the
time has changed, earth is still
there, the hour hand, or
the hand has moved.
But so have the constellations.
The sun is moving with the
constellations across the sky.
So has the moon.
It's moved from over
here, up this way.
Everything is moving
together across the sky.
If you came back a day later,
well, let's just go back and
look at it a moment before, or a
couple hours before, two and a
half hours before, and again,
here you can see the moon, and
the sun, and the constellations
moving, but Earth is immobile.
So if you came back 24 hours
later, the sun would be up there
again, but what the biggest
change you would have noticed
was the moon, moving about
thirteen degrees this way.
If looked carefully, or looked
at after a few days, you would
begin to notice that the sun is
moving with respect to these
constellations, these signs of
the zodiac.
It's slowing moving into Gemini,
and through Gemini, and then
through Cancer, at about one
degree per day.
This, these are elements of the
geocentric model, the Ptolemaic
model of the Heavens.
And when Galileo was with the
Doge, at the top of that tower,
just a couple hundred feet away,
and a couple hundred feet up,
this clock was there.
Been there 110 years.
But when the clock was built,
something else was
happening in Europe.
Nicholas Copernicus
was 26 years old.
Eventually he would put forward
the heliocentric model, with the
sun at the center, and the
phrase revolution, the term
revolution would be
used in a new way.
Something was cooking.
Now within five months of
Galileo's visit to the top of
the tower, he had gotten the
idea that if he stepped up the
magnification from five or 10
power up to 30 power and turned
it skyward, he could use it as
a tool of scientific
investigation.
I wonder what the sky looks
like, might have been what he
was asking himself.
And he got some surprises,
some amazing surprises.
And he shared them with the
world in a magnificent book,
"The Starry Messenger,
Sidereus Nuncius, in 1610.
Published fairly early in 1610.
Describing his observations,
this book was so amazing, had so
many surprises about life and
about the universe around
everybody that it was within
five years, it had been
translated into Chinese among
many other languages.
What he saw challenged the
geocentric theory.
Some of the things that he saw
were just not consistent with
the geocentric theory.
This is a new tool of
technology.
Never been around before, never
been used in astronomy before
and now we see that what the
Greeks have put together
may not be correct.
And it set in motion
so many things.
Twenty-four years later he was
brought before the inquisition
and ultimately convicted of
heresy at the direction of the
Pope, I believe Pope Irvin VIII,
sentenced to house arrest for
the remainder of his life.
But, these observations with the
telescope ignited the first
golden age of astronomy.
During which a new tool of
technology was brought into play
and new ways to understand the
cosmos were introduced.
Now we are in the
second golden age right now.
We have only recently been able
to get beyond the atmosphere
with our, you know, some of us,
and also with our technology,
and the Hubble space telescope,
other telescopes, other probes,
going to other worlds, we are
just learning things about
astronomy at such
an amazing rate.
I would think that no Greek or
Italian astronomer ever dreamed
of such wonders,
knowing such things.
But we could not know those
things without having learned
what we learned
in ancient Greece.
And it happened about twenty-six
centuries ago in a small city in
the eastern coast of the
Mediterranean, where we begin to
approach nature in
a different way.
We, well none of us were there,
of course, although you might
have doubts about me, but
it's part of our heritage.
The city was Miletus.
Don't hear about
Miletus all that much.
It was a commercial town, it
had, was a port, it had commerce
with Babylonia, Egypt,
there were ideas that
came into this town.
It was a note-worthy
town, in other ways.
It was a colonizer.
They set up 90
separate colonies.
At least that many were
identified in some of the
history books, and it played a
role, what took place there
played a role in the next few
centuries turning science into
what has been called the
greatest invention of all time.
Greatest invention
by human beings.
I think you could probably argue
with me with some other things
that you should consider, but
it is our way of finding
out about the world.
And upon that understanding
we build technology.
We make our lives hopefully
better, doesn't always work that
way, but over time
that's what we hope.
That's what we've come to see.
For peoples of those, of that
era and before, the sky was
common knowledge.
You didn't have a watch on your
hand, or cell phone, to check
the time, you didn't have a
calendar on the wall, probably,
but you could glance at the sky
and a quick look in the sky a
glance at the Eastern horizon at
dawn, seeing what constellation
was there would tell you
what time of year it was.
And it was mentioned in
literature, I am sure much of it
has been lost, but in the
Odyssey, one of the portions, in
one part of the story I believe
it is Calypso, who talks to
Odysseus and gives him
instructions on how to return to
Ithaca, it's when the winds are
bagged up, and only the west
wind is allowed to blow, and he
says, well, how do I steer?
And he's told well, keep Great
Bear on the left, that's north
and sail towards the
rising point of Pletes,
the seven sisters.
And that would send him
on a course due east.
Wouldn't work today,
but it did back then.
And I'll hope to mention
something about that later on,
probably best if
I mention it now.
We've got a slow wobbling of the
earth's axis called precession.
That changes where
the Pletes is in the sky.
It's no longer on [unclear
dialogue] equator,
it not longer rises due east.
It's quite a bit north of that,
and if you sail towards it right
now, it would probably be
about 25 degrees north of east.
So don't follow the
instructions, don't use Odysseus
or the Odyssey for finding
directions in the Mediterranean.
Probably GPS would be a
little better these days.
Chinese and Babylonian
astronomy come up periodically.
These go back earlier than 6th
Century before the Common Era,
there are written records that
are around from at least about
750 BC for the Babylonians and I
am not sure how much further
back for the Chinese, but these
were major institutions in both
countries, both
civilizations, astronomy was.
The astronomers were charged
with doing certain things.
In China it was mostly to
keep track of the calendar.
There were certain rituals
that had to be carried on.
And of course to the extent
that astronomy is tied in with
agriculture, needing to know
when to plant, and do other
things associated with
agriculture that was important.
In Babylonia, they had
different motivation.
They seem to be very interested
in finding correlations between
things going on in the sky and
things happening down here.
King dying.
Well, if that's in any way
associated with what's going on
in the heavens I would imagine
the next king is going to want
to know can I get some
advanced notice of this.
Can I get some warnings?
Looking for correlations.
Maybe a king dies when there's
an eclipsing, or maybe when a
comet is observed or
maybe when Jupiter is
in a certain constellation.
Well, observations were made,
correlations perhaps were found,
sometimes they probably thought
they were cause and effect
relationships, the
correlations, nevertheless,
sometimes we are there.
In the data for the Babylonian
astronomy, we have centuries of
data on solar eclipses.
You can go back through those
and if you do carefully, you'll
start to see that there is a
pattern, not for everyone, but
there's it turns out they
eventually found that every
eighteen years, eleven
and a third days,
there's a solar eclipse.
A Saros cycle.
But in both places they did not
have a conceptual understanding
of how earth fit in with the
cosmos, how it was all arranged.
The geometrical arrangement.
This was an
invention of the Greeks.
To the Babylonians,
they kept numbers.
They kept dates.
And you could just not even
think about how they were
related, geometrically, just
look at the dates for patterns.
Carlo Rovelli, and I am going to
show a slide of this, but I was
handed this very recently,
in the last few minutes.
The First scientist,
Anaximander and His Legacy.
Carlo Rovelli an excellent book,
I read it this summer, stumbled
across it and, it's not very
long, but it's full of great
stuff about a great man
that Rovelli feels
was the first true scientist.
Others earlier, earlier
times, have suggested that
Anaximander's predecessor,
Thales, was the first.
But his comment, Rovelli's
comment, at a certain point in
humanities history, the idea
came into being that it was
possible to understand these
phenomena, atmospheric,
geological, astronomical.
Their interrelation causes
connections without recourse to
the caprices of gods.
This immense turning point took
place in Greek thought at the
sixth century before the Common
Era and it is consistently
attributed to Anaximander in all
of the ancient texts.
Aristotle talked
about Anaximander.
Others did too.
Unfortunately we have I think
close to thirty words of his
that we've actually, that
actually come down to us.
And it's sad but there still
hope for finding one of his
books, but we are going to learn
a few things about him today,
I think.
That's what the cover of the
book looks like, if you didn't
see me hold it up there.
Planey, historian remarks that
it is said that Anaximander of
Miletus first opened
the doors of nature.
He stopped asking which god thew
the thunderbolt, that struck my
friend Joe, or that scared
the bejeeebers out of me.
Stopped asking questions
like that and
started looking
for other things.
Rovelli comments that when he
opened the doors of nature,
Anaximander ignited the
conflict between two
profoundly different
ways of thinking.
They are still around.
On one hand, there's the
dominant mythical and religious
way of thinking based in large
measure on the existence of
certainties that by
their very nature,
could not be called
into question.
And putting it in modern terms,
if a person believes in the
bible, the Koran, the Torah, and
believes that a many individuals
believe in one of these texts,
will believe in the inerrancy of
the words that are
written there.
Cannot be called into question.
Observational data doesn't
make any difference.
On the other hand, there's the
new way of looking at the world,
based on curiosity, rejections
of certainties and change.
Rejections of certainties,
also based on change.
Ok, this conflict has run
through the history of western
civilization century after
century, with all the outcomes
it is still an open question.
The clash, which we see
strengthening today.
It is measured in millennia
rather than centuries, in
Rovelli's view.
It does not get
changed very quickly.
Another Anaximander biographer
Dirk Coupri says an astounding
thing based on what we know
about Anaximander, we are
convinced that he is one
of the greatest minds
that has ever lived.
And he does not hesitate to put
him on a par with Newton.
These were people like us.
Human beings,
approaching the world,
but without a foundation
of understanding.
Without the principles of
physics or astronomy or
of any science, really.
Trying to learn those
basics that well,
we think they are basic today.
Anaximander is said to have
drawn the first map.
I don't know, I wouldn't be
surprised if others were drawn
but lost, but he drew an earlier
map than this, and Hecataeus, I
believe of Miletus, who
overlapped in his lifetime with
Anaximander drew this one.
This is better than the one I
saw for Anaximander, so I
included this one.
You see some cities here
that are worth noting.
Babylon, Memphis, and Thebes, in
Egypt, Miletus, of course,
Athens, Sparta is not
shown, Syracuse,
a Greek outpost in
Sicily and Carthage.
That would have some
interesting history coming up.
Rome is not shown.
Venice is not shown.
But there is an Etruscan city or
village, outpost, I believe,
very close to where
Venice is right now.
And Florence by the
way is over here.
And the known world, the known
land is surrounded by ocean.
We know more of the world today.
Oh another city
that is not shown,
but will become important
is right here.
Will be right here.
It's Alexandria.
More details of the Eastern
Mediterranean in Miletus is
right here, very close to this
but not mentioned is Samos,
where a couple of
astronomers are from.
It's just off the coast,
I think an island.
At Anaximander's birth, humans
have been living in cities for
at least ten thousand years, the
great kingdom Egypt had been in
existence for 26 centuries and
were looking back 26 centuries.
So, it was interesting.
Thales the predecessor to
Anaximander visited Egypt and
asked, how tall is that pyramid?
They said, why ask us,
we don't know.
Well, how do we measure that?
Do you think we were
around when it was built?
I am paraphrasing, of course.
And he figured out a way to
figure out how tall it was.
He waited until his
shadow length was
the same as his height.
And measured the length of the
shadow of the pyramid.
I imagine that was
included in future tours.
Do you know how tall this is?
Babylon with 200,000 inhabitants
it was the largest city in the
world and had been
for centuries.
And the Babylonians by this time
had developed the concept of,
many concepts of the sky and
that Rovelli points out are
pretty much included in Grade
School curriculum, we teach them
to our seven year olds.
That's what we mean by real
advances back then.
Thales is commonly referred
to as the first scientist.
Anaximander studied under him.
He is said to have predicted the
solar eclipse, and from this we
think a lot of people think he
had access to the Babylonian
tables of data.
It's hard to see
how he could have
predicted an eclipse otherwise.
And certainly with the
commercial connections with the
Babylonia, that was possible
for him to have access to it.
Believed the universe came from
water, that water was the common
element of the universe.
He introduced deductive logic.
There are several theorems that
he is responsible for, theorems
in geometry, he used geometry I
mentioned in finding the height
of the pyramid, but also from
two different points on the
shore you can
measure angles and
determine the
distance to a ship.
That could be
very useful to you.
He held that the earth is
flat and floats in water.
You know, a child asks you, why
is the sky blue, or how far is
that town you are talking about?
We took our grandson to the
beach in South Carolina this
summer, and he was astounded
how far a drive it was.
But the world is bigger still.
We come into the world with lots
of questions, develop more.
This is at a time when they were
answering some of the basic
ones, or trying to.
Why the emphasis on Anaximander
if Thales is thought of in the
way that I indicated here?
Part of the reason is that
Rovelli is looking at it as a
scientist, not as a historian.
Just how do these ideas that
Anaximander is supposed to have
introduced, how do they, what
do they take, what is the
conceptual leap from attributing
actions to the gods, to
explaining the phenomena in the
way that he did and he feels
that they are
extraordinarily significant.
There are far more wide-ranging
than Thales although Thales was
very interested in lots
of different things.
From meteorology where he had a
very good understanding, where
the water evaporates and
turns to rain eventually.
Wind blows and it moves
the clouds around.
Biology, biological evolution,
he is most noted for that
in modern science.
Geology and Astronomy as well.
Anaximander was a student of
Thales but did not feel
compelled to support his
worldview, and this Rovelli
thinks is an important
aspect of science.
If you can think of a follower
of a, think of a leader in a
religion, and a follower, the
follower doesn't just turn
around and after the leader has
perhaps passed away, and start
coming up, or start suggesting
that well, the leader wasn't
right on everything.
Let's go off in this direction.
Well, that sort of
loyalty in the
scientific realm
is possible too.
I really, if I am a student
under Thales, boy he was a smart
guy and I am going to
stick with his ideas.
No, that wasn't what happened.
Every idea, even if it was an
idea held by a professor that
you studied under, and you felt
very obliged to that professor,
you'll knock that off the
pedestal very quickly if you
find good reason to.
Observational,
experimental evidence,
go in another direction.
A very important aspect
of science that we see
here first with Anaximander.
At least Rovelli is identifying
this as a very important step.
Now one of the things that
Anaximander did, before this
time, of course, we have had
concepts of the world being
held up by something.
We didn't know, or have an idea
of gravity and how it works.
Nothing like that at all, and
you are just on one side of the
world, you don't go to the other
side and see that there are
people standing on that side,
pulled towards the center.
But, the Bible talks about the
pillars of creation, holding the
earth up, we have other cultures
talking about turtles and
beings, and we've got
Atlas, I believe carrying
around the world.
But Anaximander looks at the
stars in the sky, looks toward
the Northern Horizon, sees the
stars, some of them above the
horizon going around and around,
you can see them doing that in
the night, there's nothing
obstructing them, and other
stars rising over here, and
moving across the sky and coming
down and hitting the horizon and
then they must go below the
horizon and the reemerge.
There can't be anything
in the way down there.
We are floating in the void,
and Rovelli thinks this is a
tremendous step.
And Anaximander was asked,
"Well, why don't we fall?"
And Anaximander says, "I can
see no reason why we should."
I don't see the mechanism
that would cause us to fall.
This is a depiction
of his worldview,
the world as a cylinder.
Doesn't sound very right.
We know it is not right.
The world is a cylinder.
You've got basically that map
that I was showing you before
right up at the top of this,
this height of the cylinder he
says is about a third of the
distance across, and there's air
and fire and the sun I'm not
going to go into it very much,
but it's a cylinder.
We think of the earth as a what?
What shape?
Hope you know.
It's a sphere.
You know, a sphere could
impress us I guess.
They thought if you come up with
a sphere, but here's the first
person to put any kind of
curvature into the earth.
The next step is a sphere,
but that's not right either.
The earth is not
a perfect sphere.
This distance through the center
from pole to pole is less than
from equator across the equator.
It's not a perfect sphere.
It's an oblique spheroid.
And then you start taking a look
at the mountains sticking out
and you end up with something
that is vaguely reminiscent if
you exaggerate it's of
a pear shape.
So, should we be critical of
later individuals who said the
world is a sphere?
No, everybody makes progress.
Science makes progress
step-by-step, building on what
was known before.
And this was a tremendous
step to add some
curvature to the earth.
This person said something
like A squared plus B squared
equals C squared.
Pythagoras.
And the Pythagorean
hearth of the universe.
I won't spend much time on this,
other than to say what I said at
the outset that he has the sun,
going around the central fire,
he has the earth going around
and it's not quite, well it's
not a geocentric system, it's
not a heliocentric system.
But he's looking for a way to
explain geometrically the
arrangement of these objects,
some of them in the sky, and
another on the earth.
What's the arrangement?
How do they move?
Pythagoras of Samos.
I will say that's the
pronunciation, lived in the
sixth century BC also BCE, held
that they earth is spherical,
probably the first person to
suggest that, and what he saw
was that the ships sailing away
from the shore disappeared hull
first, and then later the sail,
and it's not just the ships, if
you are out sailing, and you
find a Greek island off in the
distance, what do you see first?
You see the tops of
the mountains.
There are usually volcanic, or
at least have some vertical
relief, top of the mountains and
then you get closer and those
are in view, but also lower
down on the mountains.
First to suggest that the sun,
moon, and planets could be
described by numbers and
mathematical precision.
And he's apparently the first to
suggest at least in Greece, that
the morning star and the evening
were the same, the planet Venus.
Plato introduces us to the
idea that the heavens
must be perfect.
And I don't know that you know,
maybe it was thought that way
before, but now it's got a
geometrical sense to it.
The only permissible path must
be the circle, perfect shape,
flat shape, plain shape figure,
and three-dimensional bodies
must be spheres.
Changes do not occur
in the heavens.
They can't improve upon
perfection, so it must be
timeless and eternal.
Comets and meteors must be
things going on in the
atmosphere, somehow.
We still think that of
meteors, we do not think
that of comets anymore.
Heavens are composed of a
perfect material, invisible,
crystalline material
better than diamond I suspect.
Quintessence or ether.
Aristotle, student of Plato, I
could spend a lot of time
talking about him, I am
going to resist doing that.
I think he has been talked
about a lot in a lot
of other presentations.
He gives us the geocentric
theory the earth in the middle,
the moon going around, and so
on, the sun out past Mercury and
Venus, these two planets are
called inferior planets and then
there is a sphere of stars out
here, and then invisible to us,
is the sphere of
the prime mover.
We still have still use,
in astronomy courses,
models of the celestial sphere.
Now, we've to an earth in here
that's much too big, it should
be just a little speck inside,
but it helps us to try to see
where we are and what we might
see in the sky if we've got the
star in a reasonable size,
and we can pick out
landforms on the earth.
And that was in a sense the
limit of the cosmos to the
Greeks, the limit
of the universe.
A bit past Saturn.
In truth, we should look at it
as a three dimensional system,
and not just circles.
What Aristotle was suggesting
was that there are these
spheres, and there is a sphere
for each planet, and the planet
was on a sphere, and
there was some kind of
mechanism that involves these.
And I jump way ahead.
There are a lot of individuals
who contributed in between.
I am skipping them, skipping
Udoxes, skipping Abalonius, and
a few others who
contributed to this.
They added more sphere, Udoxes a
student of Plato actually adds,
comes up with twenty seven
spheres, all made of the perfect
crystalline material, each one
for an object and some extras to
help them move properly, and
later individuals expanded to at
least 55 spheres.
And I would not have wanted
to bring that model
in if one existed.
Now Claudius Ptolemy looked
back, these years are not BCE,
these are AD, he looks back, he
does a great deal of astronomy
himself, observations, but he
also takes the observations and
the ideas of previous Greeks and
he puts them together in the
best model he can, to explain
the observed motions of the
planets of the moving bodies in
the sky, the stars as well, all
the stars aren't all that much
of a problem, because all you
need is a sphere and
you just rotate it.
Or let nature rotate it
or the gods rotate it.
The introduction here something
included by Ptolemy is that yes,
the sun is out here past Mercury
and Venus, but Mercury and Venus
are never seen, far away from
the sun and the sky, we see it
tomorrow morning if it is clear,
you'll see it in the eastern sky
before the sun comes
up, very bright planet.
Last year we saw it in the west,
after the sun had gone down.
But angular, speaking of angle,
never more than about 42 degrees
away in the sky from the sun, so
he decided the only way that was
going to work was if he forced
Mercury and Venus the center of
their motion, to lie
up along a line
joining the sun to the earth.
And the planets themselves are
moving on Epicycles, circles,
secondary circles
are introduced here.
And each of the planets has one,
it takes Venus from one side of
the sun to the other, Mercury
too, but the superior planets,
the planets that today we think
of as farther from the sun, that
we are, these are planets that
have epicycles, but they are not
constrained in the
Ptolemaic system to be
close to the sun at all.
So they can get on the
opposite side of the sky.
But what happens for all the
planets is that when they are on
the inside of the epicycle,
they are going in the opposite
direction relative to the
direction the center of the
epicycle was going, each center,
and imaginary point, is moving
in a circle on a
deferent around the earth.
And the combination of this
leads to the planet backing up
amongst the stars.
Why would he do this?
Because that is what
they are seen to do.
Occasionally they
change direction.
Now, here is a probably
a simulated version
of a view of Mars.
Photographed at one-week
intervals, let's say, moving
with respect to the stars.
Moving in front of the
background stars, still moving
across the sky from east to west
in a night, but not being close
to the same point
amongst the stars.
A week later here, here,
here, and then it slows down.
And then it starts going
backwards, and then it stops
again and start
going forward again.
Today we understand this is, we
are going around the sun, Mars
is going around the sun and we
pass it up, so it looks to us
from our moving vantage point
that it's going backwards.
But if you put the
earth in the center,
that's not going to work.
You've got to come up with
another system, and that's the
system that Ptolemy and other
before him came up with.
And this worked very nicely
qualitatively, but Ptolemy was
really trying to put
some numbers into this.
Put mathematics to this, and it
became necessary to add extra
circles, and we've talked
about this in astronomy class.
Remove Mars and put there an
imaginary point that has another
circle going around it, so that
Mars is moving in a circle
around an imaginary point
that is moving around another
imaginary point, that is moving
around the earth, and you've got
some more numbers
you can adjust.
Another circle, size, and
speed that you can adjust and
eventually there
were 28 circles,
and that was just for Mars.
It was a cumbersome model, but
it worked better than anything
anybody had ever had before and
Ptolemy was proud of it.
Very proud of it.
It had all been done with
circles, and spheres, and of
course the heavens have to be
done with circles and spheres,
because we know these things are
right, that they are perfect.
Earth was a sphere.
Did not move in any way.
That was part of
the accepted view.
Earth was a sphere.
Not that it was a flat place.
And the sphere marked the limits
of the cosmos only slightly
further than Saturn.
The Ptolemaic system went
unchallenged, virtually
unchallenged for 14 centuries in
that sense it would have to be
the most successful
scientific theory ever.
That was wrong.
But we're always, we are coming
to grips with being wrong.
If you are in science
that is what you learn.
Yeah, I've got an understanding,
but I've got this little bit of
uncertainty out here about just
how right I am about that.
So I am always testing, if I am
in research, that's my field.
This model came to be accepted
by the Roman Catholic Church as
an article of faith, thereby
greatly discouraging
scientific inquiry.
Putting the earth in the center
was seen as consistent with the
idea of creation in Genesis.
And because of this, and
probably because of other trends
that were going on in societies
at this time in the Romany
empire, certainly and later it
became frozen in place.
But being frozen in place, being
understood, to be the
explanation undoubtedly help to
provide some uncertainty, or
excuse me, some certainty to the
people who lived in those times.
But there were other
individuals who learned things.
People who contributed greatly
and I want to touch on them.
These things eventually some of
them, would come back to make it
difficult for the
geocentric theory to stay
as an accepted idea.
That, and the
telescope, certainly.
Aristarchus of Samos, I've
identified his life as about 300
BCE, that was right after the
death of Aristotle, and again
that is close to Miletus.
His method of determining the
relative distance from the earth
to the moon and to the sun, now,
if you think about the moon
going around the earth, when
it's in the direction of the
sun, we are looking at the dark
side of the moon, and we call
that new moon, and it moves in a
counterclockwise sense, if we
are looking down on the
North pole, whether you are a
geocentrist, or a heliocentrist.
And if the sun is infinitely far
away, then this angle is going
to be 90 degrees when the moon
is seen as half-lit, what we
call first quarter phase.
But if it's not infinitely
distant, the angle can't be 90
degrees, and Aristarchus
made an effort to measure it.
Very difficult to do, because
how can you be certain of the
moment when it is half lit.
It's tough, that part
of the difficulty.
And then measuring
the angle properly.
He got 87 degrees, now that
may have, what he may have been
doing is setting a lower limit
on the angle, but today we take
a look at it and it's almost 90
degrees, just a little bit less,
and what the results suggest is
that the sun is about 19 times
as far away as the moon.
And it's a whole lot further
away than that, but with that,
he can take the additional bit
of information that both the sun
and the moon fill up the same
angle in the sky think of a
solar eclipse the moon just
barely covers the sun, so, if
the sun is much further away, 19
times as far away, it must be 19
times as big across, the result
not only says that, but it also
says the sun is
bigger than earth.
And with that in mind,
Aristarchus suggests that it's
the sun that's at the center.
How can something bigger
than earth go around earth?
And he also suggests that the
universe is much bigger than had
been thought of.
Now there's a test for this.
You can watch the stars,
see if a close star,
and look for close stars.
And if one of the stars seems to
change direction over the course
of six months, that would be
evidence that it was well, that
earth was moving.
But it could be seen.
The reason we now know, is
the stars were too far away.
They still are too far away.
Not just in past tense.
But to the Greeks they could
see no reason to adopt the
heliocentric model.
Now Eratosthenes was
a librarian.
I have to mention the
librarian in here.
He was chief librarian of the
Library of Alexandria, and he
learned that in the town of
Cyene, which was far south along
the Nile, up the Nile, because
it flows to the North, on the
first day of summer, the
sun is straight over head.
Tall poles cast no shadows, and
the sunlight went right down to
the bottom of the well.
But in Alexandria where he was,
the sun was not at the point
straight ahead, the zenith.
It was seven degrees away.
And he sketched it out something
like this, and realized that he
had the tools to figure out
something very important.
He had a distance known or found
out, or surveyed, or estimated
between Cyene and Alexandria and
from that, well, that must be
7/360th of the
circumference of the earth.
And hence came up
with a value for the
circumference of the earth.
That by some accounts was
correct within one percent,
by some accounts.
But, not sure which units he was
using, there were too many
stadium units by this time, the
length of the Olympic stadium in
Greece, so he might have been
off by more, but giving him
credit for the best possible, he
had the best estimates of any,
looks like Posidonius did quite
well too, but I'm not sure
that's right, but Eratosthenes
was very close to the true
circumference of the earth,
what we now measure.
And so when Columbus set sail,
and that would have been 17
centuries later, there's not a
question will the earth is flat,
excuse me, I just bit
my tongue, not good.
It's not a question of whether
the earth is flat, it's a
question of just how much,
how far he can sail safely.
Can he carry enough provisions?
Hipparchus is considered by many
to be the greatest astronomer of
Antigone's and certainly for his
observational prowess, if you
look into the northern
sky, you will see and,
let me try to block and shade
this a little bit, no, I'm not
wide enough, I'll have to have
to more pizza, thank you to the
astronomy club last night.
But we've got Polaris, and Ursa
Minor, and the little dipper and
the big dipper over here as part
of the great bear, and we've got
Casiopia the queen of Ethiopia
over here, and many other star
patterns that have been named by
the Greeks, and civilizations
before them as well.
And Polaris is almost
directly overhead the
North Pole of the earth.
So, it doesn't move much.
It helps us find our way
if we have forgotten
to take our GPS with us.
And looking again at that slide
I showed you before you see one
star close to the center that
does leave a little trail, it's
a little bit brighter than any
others in the vicinity, that is
the star Polaris,
the North Star.
Hipparchus saw a nova, saw a new
star appear in the sky and it
angered him, not seeing it, but
that when he went to the star
charts he couldn't tell.
They weren't good enough to
be able to tell if this was
really a new star.
So, he started plotting out
stars on a new chart, a new map
of the sky, so that future
individuals who if they saw a
new star, would be able
to tell, was that star
there before or not.
And when he did this, he had a
chance to check and compare it
with another map that had
been drawn centuries before,
and lo and behold, the point
in the sky about which
everything was turning
was a different point.
The sky was precessing.
The North celestial
pole is moving.
Today it's right by Polaris, in
3000 BC we now know it was by
the star Thuban and Draco and
that's 5000 years of time so
maybe take half of that, 2500
years a little bit less than,
right down in here was the point
that the sky was turning about
back in the Hipparchus day.
He was able to find out that the
earth was, the earth's axis is
wobbling, it like a top that you
spin on the kitchen table or
kitchen floor and not only
does it rotate, but it
also the axis does this.
The earth is a spinning top.
He didn't know that that
is what is going on,
but that's what it was.
And 26,000 years, very
slow movement.
That much time will be required
to bring the North pole of the
sky back to the same spot.
He had a method measuring the
distance to the moon as well.
That wasn't mentioned on
that drawing before,
but he had a different method.
I want to close with this quote
from Carlo Rovelli, I've quoted
him quite a bit, again it's a
book I would recommend reading.
'Science above all is a
passionate search for always
newer ways to
conceive the world.
It's strength lies not in the
certainties it reaches, but in a
radical awareness of the
vastness of our ignorance.
This awareness
allows us to go on
questioning what
we think we know.
And have learned, and thus to
continue learning.
Not, certainty, but a radical
lack of certainty nourishes the
search for knowledge.' It's not
the same rock as an ardent
belief in a religious text but
there's no reason one can't have
a belief in a religious text
and a love of science.
There's so much that
we have to learn.
There's a whole lot to be
learned 26 centuries ago,
there's still a lot
to be learned now.
We keep finding that every idea
that gets accepted eventually
gets knocked off the pedestal.
And that is my
contribution here.
Thank you.
