Translator: Federico MINELLE Reviewer: Denise RQ
Light, where does light come from?
All the light around us,
even the one coming from these lit objects
comes from the sky.
One way or another it reached us, maybe some time ago, from the sky.
Light comes from cosmos only.
From which cosmos? From the one around us.
From this sky, that we cannot see in our city.
Bergamo cannot see this sky, you can see this sky in Africa only.
You see it in the dark, when the city doesn't illuminate night sky.
If you happen to go in southern world, you can see this sky.
Well, let's imagine to be some time ago,
two and half million years ago.
There will even been a first hominid in his evolution phase
who raised up from the ground
and he realized what he got above his head.
Imagine that moment, an important moment for our history
that comes from the remote ancient times.
From that moment onwards, man always had with him in his culture
the awareness of universe and of light coming from the sky.
Let's have a quantum leap.
You know this profile very well.
It's Stonehenge profile. What Stonehenge is?
It is an achievement of a primitive people.
About 4,500 years ago,
then practically before History begins.
It is an example on how the study, the sky observation,
had shaped the human culture.
In order to make this particular building system,
that ancient people did a huge effort,
they brought very heavy stones
from dozens, perhaps hundreds kilometers far away,
to structure them in a very large circular frame.
Why?
In order to watch stars.
To see planet motion, to understand when it is sow time,
when to harvest.
In order to do rituals related to mythologies,
just related to information coming from the sky.
Sky always shaped our culture:
Mayan, Egyptian and all the humanity history
and, according to this example, using technology,
most advanced features at that age.
Let's have another jump, about 2,300 years.
We are in the Mediterranean Sea,
a Greek-Roman ship carries some goods
between Greece and Italy
and it sinks in front of Kythera Island, a Peloponnese island.
In 1906, at previous century beginning, this wreck was found
and while collecting the wreck stuff,
in the hold of a 2,200 years old ship
at that point, apart from the usual amphorae,
structures like these were found, some sort of small wheels
completely covered with limestone, brought to Athens museum
and left there for 60 years long. Nobody knows what they were.
60 years later, they make them radio-graphs with x-ray
and discover within those wheels some very thin gears
like clocks of 1600 century, but we are in 200 b.C. century.
This was some sort of astrolabe,
a system which allowed to powerful people of that time
to compute planet motion, above all sun and moon eclipses.
Imagine what does it mean for a General, or for a politician,
to know when the sun is going to hide, when the moon is going to be overshadowed.
An incredibly sophisticated technology.
Marcus T. Cicero told us that two of this machine type,
were available at that time, in the Greek-Roman civilization.
We found one of them undersea, an extraordinary good luck!
Another example of how technology, the more advanced one,
had been made available,
but for what?
In order to study, to understand the sky.
Let's have another jump.
This is an Almagesto page.
Almagesto was a sort of encyclopedia, like the Britannica one,
where all the information known to mankind were collected
in one thousand years between the end of Roman Empire
and half of first millennium.
As you can see from these images, Earth is perfectly shaped.
It has all its continents: North and South America, even Australia.
What's the problem? It is at the center of the world.
All the celestial spheres surround it.
The one carrying the Sun, the one carrying the Moon,
the various planets, gradually up to the sphere that leads to the fixed stars.
Indeed, being in 1550, America was discovered by Columbus in 1492,
but it is not yet a clear understanding where this planet stands
within the Universe.
Indeed, we have to wait until 1609, when Galileo,
using this small spyglass which you can buy with 50€ in a general store,
understood that some satellites were turning around a planet, Jupiter,
and that they were drilling, ruining,
they were destroying celestial spheres harmony.
At the end Earth found its position in the Universe.
The Sun was not turning around the Earth,
but Earth was turning around Sun.
Spyglass, the technology of that moment,
now, the technological development leads to extraordinary progresses.
This is a previous century spyglass,
it is the spyglass through which Hubble looked at our galaxy for a long time,
he took pictures of our set of Stars,
that then it was thought to be the whole Universe
and while studying some small stars, a bit blurry,
from night to night he understood that other galaxies exist,
very, very far away.
From night to night Universe expanded
by a factor of a thousand more
and from then on we continued expanding it,
up to, pretty much, to its origins.
This by using a telescope clearly very much powerful than Galileo's one.
Today we have in space the telescope of telescopes:
Hubble telescope, which looks at the Universe
using extraordinarily favorable conditions
being able to do observations from the space
and this picture you can see on the right side
is a Cosmos pinhead on our head above
hugely magnified by Hubble
and we can see early galaxies, early protostars,
we can see an Universe how it was billions and billions of years ago.
I told you that technology is fundamental to understand the Universe around us
but you'll see how amazing is the pace
of technology evolution in the last century.
Last century allowed us to do much greater advancements
than in thousands and billions of years before now.
You can see this picture, we are in Scrovegni Chapel
and we see how in 1301 Giotto painted a wonderful series of paintings
including the Nativity and you can value this painting beauty
because we can see the shape, the persons images,
animals, a hut perspective
but above the hut we see a ugly comet
some sort of reddish shapeless small ball
and we wonder why a so great painter as Giotto was
had drawn a so ugly comet.
Because he had seen it in the sky, because in that moment he saw
that star passing on his head.
It is Halley comet, which passes each 76 years
and in 1301 it was passing on this painter's head
who precisely copied it.
In fact, these photo in 1910, first ones of this comet,
show us a structure totally similar
to the painted one by Giotto in 1300.
In 1986, 76 years later,
man was able to make his artificial satellites
his remote-controlled robots
which literally went to pinch the tail of Giotto comet
In order to see how it is made.
600 years to go from eye to photography,
76 years to pass from photography
to the ability to reach Halley comet.
Technology, technology.
These gentlemen are Penzias and Wilson,
two engineers who become famous
because substantially they authored a paper which says:
we tried to build an electronic equipment
with a very low environmental noise
which had practically to measure no one of any noise types
and we hear a continuous, deafening noise,
coming everywhere from the universe.
This equipment has its own ear,
which is an antenna, a sort of a big radio antenna,
which allowed them to realize that their noise comes from everywhere.
They don't know what they had found, published this finding
and after a few later, others understood
that they were listening to the Big Bang echo
and they awarded Nobel prize for that.
A noise which is actually the echo of the initial big explosion.
Today, we perform studies of the same kind using more powerful equipments.
This stratospheric balloon studied that Big Bang echo,
understanding that it has a very particular structure.
If you wear glasses in order to see the Big Bang
they are a sort of someway special Goggle glasses,
made by scientists studying these things
and you get out to see the sky, you'll see a pocked one,
as it had measles.
That measles is the detail of Big Bang explosion,
as you can see it 300,000 years later.
Maybe you have seen a picture like this
In the headlines of main newspapers:
a satellite named Plank
completed this picture of the sky affected by measles,
Big Bang measles,
this is just a sky, which revealed 280,000 years,
300,000 years after Big Bang.
But recently you read on newspapers this unbelievable thing,
an equipment located at South Pole did much more.
It found in this picture of 300,000 years ago
a mark of something that happened
1 billionth of second after the initial explosion.
These polarized light circles in the sky
are telling us what happened just at the beginning of time.
Technology. But what happened over the past 50 years?
A very big revolution.
We learned how to see the Universe colours
which are not visible to human eyes
and above all not visible from the Earth.
The Universe seen by Galileo, Hubble, using telescopes,
is sending us the light which goes through atmosphere.
This light is a visible light which goes fairly through the air.
Radio waves seen by Penzias and Wilson are like the ones done by cellular phones,
they fairly go through the air.
But there are many other waves
that cannot go through the air,
and, in order to see them, we have to go out, literally, from the atmosphere.
Over the past 50 years we were able to do so systematically
and we were able to get all the colors of an otherwise invisible Universe.
For instance this picture you can see if we shift to visible light
is the Universe, Milky Way,
which dominates our viewpoint, seen from the Earth,
by the first hominids' eyes, by Galileo's eyes and Hubble's ones.
in the visible range.
It has some structure,
We cannot see it clearly as a whole,
but it has these features.
If we shift in the infrared range,
which is a frequency that doesn't go through the atmosphere,
we can see a totally different shape.
In the microwaves range,
the ones of the microwaves oven we have in our kitchen,
again it changes completely.
In the radiowaves range, the one we can see from Earth, too,
where are Penzias and Wilson measures, it changes again;
some set of cold gas
which appear and give out that kind of radio light.
In the ultraviolet range,
which is a color not going easily through atmosphere,
all a series of stars appear which are otherwise invisible in the visible range.
In the x-rays range, our Universe changes again,
it looks completely different with very hot sources.
To finish in the gamma rays range, which are those nuclear explosions,
where some objects are exploding in a nuclear way
inexhaustibly, since millions and millions years.
This is the Universe we have in front of our eyes
a Universe full of colours, that 50 years ago we don't know.
This is the part of an invisible Universe which has become a visible one,
which has unveiled during the last 50 years,
thanks to people work like Riccardo Giacconi,
an Italian who awarded Nobel prize in 2002
because he found Universe made of X-ray sources,
nobody believed it, "He can't do this experiment."
He stubbornly insisted, he went to America
and he made this satellite, put into orbit
and he saw first X-rays sources.
Or this satellite called Fermi,
as a tribute to our great physicist in 40-50 years,
which literally observes the very hot Universe
along an endless nuclear explosion.
Or these even more modern equipments called "Cherenkov-light" tools
which look at light with a so ultimate color
that we aren't able even to produce it in our labs
a terribly high energy
produced in some cases by those sources, energy monsters,
which are somewhere In our Universe.
This partially explains because we have so many satellites,
each is an eye looking at different colours
looking at different distances, looking at a short or long distance
reaching visible Universe borders, unto Big Bang touching.
Then we now have these beautiful pictures
of the Milky Way, but of the Universe, too in all the imaginable colours.
This is our Universe, become visible over the past 60 years,
previously its 90% was completely unreachable.
We finished, did we reach science fulfillment?
Do we get visible limits?
No, we don't.
We indeed don't yet know what is the true dark Universe.
There is a so dark Universe that light cannot be released,
not only released light doesn't go through atmosphere.
It is a Universe substantially invisible for any light type.
Then we recently learned over the past 50 years,
many things about the Universe.
We know it is flat, homogeneous, isotropic, made of radiation,
matter, protons, neutrons, as we are,
but we knows that is 4% only of the whole.
It exists a component, called dark matter,
that we know is about 23%,
six more times plenteous than usual matter
and it is in this room, it goes across us, but we cannot see it.
Not only, we understood that there is another 73%,
which is vacuum-hidden energy, absolutely unknown
beside that it exists.
Among other things, primeval anti-matter
that symbolizes Big Bang
has gone away and we don't know where it has been.
So we learned to look at all the Universe colours
but while we are doing so,
we discovered that about 95% of the Universe,
which is literally here, but invisible,
using all the techniques we invented
over the past 50 years,
So we know that we don't know,
we never have been so consciously ignorant
about nature.
So, after a century of extraordinary growth
after a literally exploding technology
that opened us all the Universe colours,
we reached a new board, a new border,
we know that 95% of what is around us should still be discovered.
So we are on the new millennium thresholds
when we have still to discover most things
which are around us.
So my meaning for this TEDx Talk is,
"AAA. We know that 95% of Universe is invisible at all.
Looking for ideas to understand what is made of."
Thank you.
(Applause)