A happy new year, and welcome to 
a new episode of
"Pure fantasy or not" Let's talk about the
recurrent question I got regarding
the existence of a multiverse or parallel
universes mostly because of my video
Stars Size comparison 2 in which I
decided to show the possibility of one
at the end using a questionmark. While
everything up to that point is backed up
by science, from there on it's a highly
controversial topic, not only in YouTube
comments also among scientists. Some
people even say it was pure fantasy.
So is it? What many argue is that there's
a lack of evidence. Does a lack of
evidence always mean something is pure
fantasy? Let's do a thought experiment.
Somebody throws a stone and there's a
wall in the way with an impossibility to
see the path of the stone. We can
estimate the path by using mathematics
based on the known laws of physics. But
you could also say we don't have
evidence therefore it could also have
gone this way. Everything behind the wall
is "pure fantasy" the problem is that we
constructed models that describe how our
universe works and whenever these models predict something you cannot just opt out
and say it was pure fantasy. You have
to start and look for evidence.
Unfortunately in the case of the
multiverse evidence is impossible per
definition sometimes, as we are bound to
our universe. It is very similar to the
problem with black holes. We know they
are real, we know where they are, but due
to all known laws of physics it is
impossible to get any information or
evidence from beyond the event horizon.
Our mathematics based on what we know
about how the universe works tell us
what happens inside, but there is no way
to get evidence for that so should we
say:
"Black holes don't heaven inside" an
inside being pure fantasy? Or should we
say science stops at the event horizon?
In some way we already know of a place
outside of our universe and you could
even send things there theoretically.
One way. Now if some models that describe how our universe works say that there must
be a multiverse we must take this
seriously.
So what are possible types of parallel
universes?
What is our universe anyway? It is all
places around us where light has had
time to reach us. According to Einstein
the speed of light is the speed of
reality. We will never get information
from places, or have influence on places,
which you could not reach with
light speed. So we are bound to the so
called "observable universe" around us. The inflation model tells us there is more
space even further from us, that travels
away from us faster than the speed of
light. So light from there we'll never
reach us. It is kind of the opposite
problem of the black hole, but we know
that there must be more galaxies out there.
You could as well say they are in
another universe. So this is a so-called
"Level 1 multiverse" There is not much
controversy about that. Given space
beyond our observable universe is
infinite. But in newer studies we even
found the first evidence for space-time
being curved. That means our universe
might not be infinite. Currently
scientists are trying to combine the
working models of quantum physics and
relativity to a single unified theory.
If the result has several solutions, it
predicts there being a huge number of
other universes with different
cosmological constants and laws of
nature. This is the kind of multiverse I
showed in star size comparison.
It would also answer the questions by these constants of nature are the way they are
we are a result of a universe with the
constants in a way that enables
there being planets and stars as well
as life. If you think about it, we have
made the same mistake again and again in history. We said the earth is the center
of the universe. No it is not. It rotates
around the Sun. The solar system is the
universe. N no it is just one of billions
having planets in our galaxy.
The galaxiy is the universe. No it is just one of billions of galaxies in the
cosmic web. Okay the cosmic web is the universe.
This time for sure. It could be that the
reason why there is a special planet
like Earth in 700 quintillion planets in
our universe could be the same why our
universe is special. This would be a "Level
two multiverse" What we don't know is if
universes can collide. If they did we
would see it in the cosmic background
radiation. The next type of multiverse is
really a parallel one. According to
quantum physics, contradictory to
common-sense, elementary particles can be
at several places at once, being only at
one place when measured, jumping through
impenetrable borders while moving or
being connected with others over
arbitrary distances instantaneously. This
is real. We can make models of their
behavior. A lot of Technology is based on
it already for a long time. Now we even
begin to build quantum computers tha, by
exploiting these facts, will be able to
calculate things that would be
impossible to calculate in reasonable
amounts of time with a regular computer.
There is an approach of explaining these
strange behaviors of particles by saying
all of the possible positions of
elementary particles are real! We kind of
calculate in different realities at the
same time. That means every outcome of
history, that could have happened, did.
There would be a universe where you have a different life for to not exist, as
real as ours. Every moment that happens
splits in a near infinite number of
other universes. This would be a "level 3 multiverse".
You know, after uploading star size 
comparison 2 two things happened
regarding the multiverse part. Pne is a
film producer asked me for the clip to
use for a pitch meeting for a series he
wanted to produce for Netflix dealing
with alternate realities. The other one
is a fellow youtuber who contacted me
producing an independent documentary
series called "Before the Big Bang"
skydivephil. He managed to have
interviews with the world's greatest
minds on cosmology, including Stephen
Hawking, about how our universe could
come into being. You should check it out.
I provided a few animations for the
project. Also keep in mind it is not
dumbed down for the audience. A few
things are really hard to grasp, but I
am happy this series exists. I'm honored
to have received contact to experts in
that topic. Link is in the description.
So, the answer to the question "does the
multiverse exist?" is still "unknown".
I would argue that the answer "pure fantasy" or refusing to deal with the subject is
the wrong approach. But let me know your thoughts. In end there is also the
idea of a "Level 4 multiverse" dealing with
the fact that something exists at all.
It combines all previous types and says
abstract mathematics itself is real and
all that it can express is a reality in
some way. This is of course the most
controversial one and I understand why.
But in some way I had a similar thought
on my own before getting more into the
subject. At the end of Stars Size Comparison 2
I wrote: "What if nothing
never existed? What if there is,
and always was, an everything forever?
I'm morn1415 and the real world is
incredible!
