The observable universe spreads across an
expanse so big that it warps the imagination. And although there is a cosmic boundary we
can see, many astronomers believe there could be much more out there in the darkness, billions
and billions of light years away. And it seems there is something strange and
mysterious out there with an immense gravity pulling on everything... Space is expanding at an accelerated rate,
and giant space structures farther than we can see could be out there tearing space apart… And we may have found one of these in our
own universe. The universe is larger than we can comprehend. Currently, we know there are at least 100
to 200 billion galaxies out there that we can now see, but it’s a good chance there
could be 2 trillion galaxies or more in our observable sphere alone, we just can’t see
them. We all know that the observable universe is
estimated to be approximately 13.7 billion years old. This is defined by the speed that light travels,
and astronomers came up with the age of the universe by measuring light that has reached
us from the oldest and most distant stars. We define ‘observable space’ by the light
that has reached the Earth and can be seen. Cosmologists estimate the oldest photons we
can currently see have traveled a distance of 45-47 billion light-years since the hotly
debated Big Bang theory. This means that our sphere of observable universe
is around 93-billion light years across. To give you an idea of how big this really
is, one light-year, which is the unit of astronomical distance that light travels in one year, is
9.46 trillion kilometers [5.88 trillion miles]. With that in mind, the big question is; how
can the universe be 93 billion light-years across if it's only 13.7 billion years old? This means that the Universe could be older,
much more than 14 billion years. We know that anything further away than the
light we see from the beginning of the universe, or the cosmic ‘Big Bang’, hasn't had enough
time to reach us. Thus, we can’t see what’s out there... It’s pitch black. But does this mean the edge that we can see
is all there is? The truth is there could be a lot more out
there. Ever since the Big Bang, the cosmos has been
growing at an increasing rate. It was Edwin Hubble that discovered that the
universe is expanding and that all galaxies are moving away from the Milky Way. Not only are these galaxies moving away from
us, but the farther away they are, the faster they are flying away from us. In fact, Hubble found that for each additional
megaparsec of distance [Megaparsec is 3.26 million light years] galaxies receded 500
kilometres [310 miles] per second faster. This became known as the ‘Hubble Constant’,
and the area of our observable universe is called the ‘Hubble Volume’. One thing we need to understand is that the
word ‘observable’ in this sense doesn’t refer to the capability of our current modern
technology to detect light or other information from an object, or even if there is anything
to be detected. Observable here in this case refers to the
physical limit of the speed of light itself which is its maximum speed. [300,000 kilometers per second] When talking about the distance of anything
in space, we’re also talking about time. Looking up into the night sky is a little
bit like time-traveling. All those glittering stars in the night are
only snapshots of what those stars looked like in the past. Just think about it, some stars and other
objects in the cosmos are so far away that their light can take thousands to millions
of years to reach planet Earth. And if there is something beyond the edge
of the observable universe that we can’t currently see, it means that these objects
are so far away from us that their light still hasn’t reached us. The cosmic horizon is the measure of the distance
from which we can retrieve information. But is there something out there past what
we can see? It’s really tough to answer this. However, to get some idea if there is something
out there, we need to take into consideration the curvature of the observable universe. The thing is that astronomers aren’t really
sure if the universe is infinitely big, or just vastly huge. In order to measure the universe, astronomers
look at its geometric curve on large scales which tells us about its overall shape. If the universe is perfectly geometrically
flat, then it can be infinite. But if it’s curved like Earth’s surface,
or is like a bubble, then it has finite volume. Current observations and measurements of the
curvature of the universe show that it is almost perfectly flat, like a sheet of paper. That would indicate that it must go on forever. We know with some certainty that there is
more ‘universe’ out there beyond the boundary that we can see. Astronomers believe that space could be infinite
with more of what we already see, and it’s probably distributed the same way as it is
here in the observable part. Now here is one of the mind blowing things
to think about if the universe is infinite. If this were to be true, then you wouldn’t
just find stars, different planets, and galaxies, you would eventually find every possible thing. Think about that for just a moment...you would
find everything. If you went far enough, you would find a solar
system identical to ours in every way, including a planet Earth, and your twin..except that
a copy of you might have eaten cereal this morning instead of a version of you that skipped
breakfast altogether. It’s a fact that some cosmologists think
if you go far enough, you would eventually find another ‘Hubble Volume’ that is identical
to ours with a version of yourself mirroring your every action. Now while that might sound impossible to what
our minds can grasp and understand, there is something else very strange and unexpected
that was discovered by astronomers in 2008. They found that galactic clusters were all
streaming in the same direction at over 3,218,688 kilometers per hour! [2 million MPH]. It is a phenomenon called Dark Flow. This movement of galaxies defies all predictions
about the distribution of mass throughout the universe after the Big Bang. So what is the mysterious gravitational pull
on all these galaxies? One possible cause could be massive structures
that are outside of the Hubble Volume that are exerting a massive gravitational influence. In simpler terms, massive objects with a huge
gravitational force pulling everything towards them. If true, this would mean that the structure
of the infinite universe beyond our view is not uniform. No one knows what these structures could be. It’s possible they are aggregations of matter,
and energy on scales we can barely fathom, or they could be gravitational forces of other
universes. Speaking of massive structures, there is one
in our universe that is so big that it shouldn’t even exist. In fact, it’s the biggest structure in the
observable universe. It’s called the Hercules-Corona Borealis
Great Wall and it measures 10-billion light years across. It’s so big that it makes up 11% of the
observable universe. To put this further into perspective, if you
were traveling at the speed of light, it would take you 10 billion years to get from one
end to the other. So why shouldn’t it exist? The problem is that astronomers have no idea
how this ‘great wall’ formed only a few billion years after the big bang, and could
have grown so big in such a short time. This means there could be giant structures
like these out there pulling on everything, including space. One day it could very well rip apart the fabric
of space-time itself. And speaking of gravitational forces from
other universes, some astronomers believe that the post Big Bang expansion of the universe
created bubbles that formed in the structure of space, and each of these bubbles is an
area that stopped stretching along with the rest of space and formed its own universe
with its own physical laws. In this scenario, not only is space infinite,
but each bubble is also infinite because you can store an infinite number of infinities
inside a single infinity. To make that seem a little more clear, even
if you could breach the boundary of our bubble, the space in between bubbles is still expanding. So in the reality of space time, you could
never get to the next bubble no matter how fast you traveled. But will we one day have the technology to
see what is beyond the edge of the universe we can now see? The sad reality is that light from any object
outside of the Hubble Volume will never reach us because the space between us and it is
expanding too quickly. For example, we may never see what a galaxy
looked like 10 billion years after the Big Bang. This doesn’t have anything to do with our
limited technology, but instead the physical limits of the speed of light itself. This means that any light emitted by objects
at a distance of 19 billion parsecs [1 parsec = 3.26 light years], will never reach the
Earth. As time goes on, more and more points in space
will have time for their light to reach us, which means that the observable universe is
still increasing in size, and that also means that the age of the universe will increase. That said, you might think that one day, if
humanity is around long enough, the entire universe would become observable to us. But since space in the universe is continually
expanding, the distance between us and everything else becomes farther and farther each second. However, the James Webb Space Telescope will
be able to look farther into space, will look backward in time, and just may give us more
answers to what else exists out there. In a sense, it is a time machine, and will
be able to see further into the past. With that said, we want to know what you think
is out there, and do you believe that the universe is infinite and there is someone
just like you somewhere billions and billions of light years away? Let us know what you think. And if you have any ideas on what you’d
like to see next, then let us know. Thanks for watching.
