Guys, this video is a collaboration with
a great channel called beautiful science. If you haven't seen it check it out. My
friend Chris makes short science videos using really cool animations. In a
previous video, we looked at the smallest scales. We attempted to visualize the
smallest size in the universe - the Planck length, which is about 1.6 X10^- 35 meters. This is so small, that if an atom was the size
of the earth... the Planck length would be smaller than
a proton. But the large scale size of the universe is equally mind-blowing. For
example, if the Sun was the size of a basketball, how far do you think the
nearest star Proxima Centauri, our neighbour would be? Would it be on the
other end of the basketball court? Would it be further, like maybe a mile away?
Maybe 10 miles away? Take a wild guess... you would have to keep going much
farther. If you were playing basketball in New York City, our neighbor Proxima
Centauri, would be about 4,500 miles away on a basketball court somewhere in
Moscow! And there are 10 sextillion such stars in the universe - that is 1 followed
by 22 zeros. And each one of them is approximately the same distance apart
from each other as Proxima Centauri is from the Sun. In fact, the universe is
bigger than even what our most powerful telescopes can see. How big is the
universe in terms of numbers? And in fact could it be infinite?
Is there any way we can even begin to visualize what infinity is? We just might
be able to do it. How?...That's coming up right now! Let's start with some genius
animations created by Carrie and Michael Huang, who have generously given us
permission to use them. The link to their website is in the description below.
We'll start with the scale of a human being and work our way up, because it
helps to start with something relatable. And the size of your body should be the
most relatable scale - about one to three meters. These would be objects like a
bicycle, or a sunflower bloom. If we go a hundred times bigger, to about a hundred
meters we will be at the scale of a Boeing 747 jet, or the size of an
American football field. Let's go a thousand times bigger than the scale of
a human - about a thousand meters. Now we're looking at the tallest building in
the world, the Burj Khalifa - 830 meters. Also, Vatican City is
only about one kilometer in length. Let's go a thousand times bigger than this - one
million meters. Now we're on the scale of California and Italy, both of which are
about 1200 km in length. We also begin to approach now
some of the smallest spherical celestial objects - the former smallest planet Pluto
which is about 2,300 kilometers in diameter.
Pluto was reclassified in 2006 to the protest of many people, especially kids,
to be designated a lowly "dwarf planet." Let's go a thousand times larger than
this scale, or 1 billion meters. We will now be going way past the size of the
earth, which is only about 12,742 km in diameter.
And we are passing even the size of Jupiter, which is more than ten times larger in
diameter than earth - about a hundred and forty thousand kilometers, or a hundred
and forty million meters. Jupiter is actually only slightly smaller than our
nearest star neighbor - Proxima Centauri, which is only about two hundred fifteen
thousand kilometers in diameter, much smaller than our Sun, which is about 1.4
million kilometers, or 1.4 billion meters. Let's go a thousand
times larger than the size of the Sun, or one trillion meters. Now we're looking at
some of the largest and brightest stars that we can see in the Milky Way galaxy -
stars like Betelgeuse, a red supergiant, the ninth brightest star in the sky,
which is 1.2 billion kilometers in diameter. One of the brightest stars in
the sky is also the largest known star in the Milky Way galaxy - V Y Canis
Majoris, at about two billion kilometers in diameter. Let's go a thousand times
larger than this, or 1 quadrillion meters. We'll be passing by the Oort cloud which
is thought to be a spherical shell consisting of up to 2 trillion comets
that surrounds the solar system. This is where an occasional gravitational
disturbance can send a comet hurtling towards the Sun, or more ominously
towards the earth. This spherical cloud starts at about 1 trillion kilometres
away from the Sun, and ends about 15 trillion kilometres away from the Sun.
This also forms the outer boundary of our solar system,
where the gravitational influence of the Sun is minimal to non-existent.
Now we're at the scale of a Lightyear, which is about 9.4 quadrillion
meters, or 9.4 trillion kilometers. Let's go a thousand times
larger than this or 1 quintillion meters. This is about 100 light-years. Now we can
talk in terms of the scale of our galaxy, the Milky Way galaxy, our home galaxy.
We're going to go past the size of some of the most spectacular structures in
the universe - things like the pillars of creation, and the Eagle Nebula, as well as
some of the smaller galaxies that surround our Milky Way galaxy. Our galaxy
is about a 106,000 thousand light-years across, or almost exactly one
quintillion kilometers. That's 10^21 meters, containing anywhere from 250
billion to 400 billion stars. Other than the fact that we live here, there's
really nothing particularly remarkable about our galaxy. It's a typical spiral
galaxy. There are billions of such galaxies in the universe.
Our neighbor, the Andromeda galaxy is larger, containing one trillion stars.
When we go a thousand times larger than this, we begin to see the superstructure
of the universe which is made up of super clusters. We live in such a
structure called the Virgo supercluster. It also contains Andromeda and about a
hundred other galaxies. It's about a hundred and ten million light-years in
diameter, or 10^21, or one sextillion kilometers across. There are
estimated to be about 10 million super clusters in the universe. When we go a
thousand times larger than this, we reach the end of the visible universe, at about
the scale of 10^27 meters. The observable universe has a diameter of
about 93 billion light years, almost exactly 10^27 meters. How is it
that the universe is only 13.8 billion years old, but it's 93 billion light
years across? Shouldn't it be 13.8 billion light years
across, if nothing can travel faster than light? That's a great question because
it's pretty confusing. First, 13.8 billion light years would be the radius of a
sphere, so the diameter would be twice that, or 27.6 billion light years.
This is basically what we see in the WMAP Our universe's microwave background
photo. In fact each of the red bumps you see on this photo has evolved into a
super cluster that I talked about earlier. But the reason our universe is
actually 93 billion light years across, and not 13.8 billion light years across
is because the universe has been expanding for the entire 13.8 billion
years. And due to the cosmological redshift, we know that the farther away
an object is the faster it appears to be moving away from us. And we can calculate
that those superclusters of galaxies, based on the expansion of the universe.
would be 46.5 billion light years from us by this time. That's the
radius, so the diameter of the universe would be twice that or 93 billion light
years across. In fact, if we waited 46.5 billion years we would be
able to see the light emitted right now from those super clusters, because the
light would have started on its journey towards us just
about now. But we will actually never eventually see this light, because in
1998, we discovered something called "dark energy," and learned that the universe is
not in a steady expansion, but rather an accelerating expansion. So that light
will be receding from us at greater than the speed of light. But isn't the speed
of light the cosmic speed limit? Yes, for things traveling within space. But
there's no limit on the expansion of space itself. The space between galaxies
is expanding faster than light. The galaxies are not travelling within space
faster than light. But could it be though that what we can actually see is just a
minuscule portion of a universe that's actually infinite? Is there any way to
determine whether the universe could be Infinite? Well, the Cosmic Microwave
Background gives us a clue. It's the leftover glow from the Big Bang. Although
it looks fairly uniform, there is a lot of information there. One of the things
that this microwave background tells us is that the universe appears to be flat.
How do we know this? Scientists look for what we would see if the universe was a
certain shape. They look for the curvature of space. If space was not flat,
but positively curved, like a four-dimensional sphere, then we would
expect to see multiple images of the same object in the sky, because distant
light rays would converge. This is like ants on a balloon
trying to measure the flatness of their 2d universe by adding up the angles in a
triangle, to make sure that they add up to 180 degrees. In a positively curved
universe, the angles would add up to greater than 180 degrees. Likewise,
distant light rays would diverge if we live in a negatively curved space shaped
like a saddle, and the angles would add up to less than 180 degrees. Data from
the WMAP as well as Planck spacecraft however, indicates that the universe is
flat, or nearly flat, with an error of about 0.4%. A flat universe would be an
infinite universe. But if the error is taken into account, then it is possible
that the universe could have a slightly positive curvature. In that case, it would
be finite, but would have to be a radius at least
250 times larger than the part that we can see. This would be a minimum size of
about 11.6 trillion light years in radius, or about 23 trillion
light years in diameter, instead of the 93 billion that we can see. This is huge,
but would be much much smaller than infinity. Infinity is a very large number.
Imagine a really large number, like a googol - the real googol, spelled
differently than what you're used to seeing. This is 10^100 light years.
That's 1 followed by 100 zeros. Or a googolplex, which is 10 ^10^100 power, that's 10 to the Google power, an extremely large number, much larger
than even the Planck volume that would fit inside the observable universe, which
would be about 4.7 x 10^185 Planck volumes but infinity would be much much larger than either of those
numbers. It goes on forever after all. Imagine the earth being a perfect sphere,
and an ant trying to figure out its curvature by drawing large triangles, and
seeing if the angles add up to 180 degrees. It may conclude that the earth is flat.
So our universe appears to be consistent with a flat universe, although we can't
rule out a curved universe. So our best guess is, right now, that the universe is
infinite. But infinities in science tend to be due to errors, so we should be
skeptical about this result. What we do know for sure is that the universe is
much larger than the part that we can observe. The problem is we only have
access to the information contained in our tiny 93 billion light year bubble,
that we call the observable universe. We can only infer from what we can see. This
is like a sailor on a boat, in the open sea, in the middle of the Pacific Ocean,
at night, trying to figure out where the ocean ends, with nothing but the Stars to
guide him. Guys, I talked about some of the largest numbers, but my friend Chris
over at Beautiful Science has a great video on some of the smallest numbers and
scales, numbers that I think you're going to find very interesting.
So click the link in the description to see his video. And if you liked this
video then please give us a thumbs up, and share with your friends. Be sure to
check out some of our other popular videos. I'll see you in the next video my
friend!
I love watching lemmino's videos about space and the vsauce mind field so thought provoking when you're baked