The Subjective Universe
1. The Visible Universe:
From our prospective, when we look out in space, we are also looking back in time. The further
out the objects, the younger they are. The furthest back we could see is when the Universe
became transparent and the photons of the cosmic microwave background radiation originated
at this time. The Universe is about 13.8 billion years old. Therefore, when we look back in time,
we can see 13.8 billion years history of the Universe. The Moon was about 2 seconds from the
past, the Sun was about 8 minutes from the past, the first galaxies (Galaxy GN-z11) that was
13.4 billion years ago (or 400 million years from the beginning of the Universe) and the cosmic
microwave background was about 13.8 billion years from the past near the beginning of time.
When observer at our location looked back in time say 5 billion years ago, we could only see
about 8.8 billion years of the history of the Universe. They too could only see up to the cosmic
microwave background that was about 8.8 billion years in the past, and the first galaxy (Galaxy
B), that was 8.4 billion years ago (400 million years from the beginning of the Universe).
When observer at our location looked back in time say 10 billion years ago, we could only see
about 3.8 billion years of the history of the Universe. They too could only see up to the cosmic
microwave background that was about 3.8 billion years in the past, and the first galaxy (Galaxy
C), which was 3.4 billion years ago (400 million years from the beginning of the Universe).
Today & from our prospective, Galaxy B is 8.4 still billion years from our past. However, it
should be around 5.4 billion years old (from the beginning of the Universe) Galaxy C is still 3.4
billion years from our past. However, it should be around 10.4 billion years old (from the
beginning of the Universe)
2. What’s Now:
It takes more than 8 minutes for light to travel from the Sun to Earth. If the Sun exploded 4
minutes or so ago, we will not know it or experience anything until 4 minutes later. So, would
that explosion be an event of our past or an event in our future?
It takes about 2 seconds for light to travel from the Moon to Earth. Imagine that we are
communicating with people on the Moon with very powerful telescopes. When we wave at
them, they will not see it until 2 seconds later. When we see them waving, it was what had
happened 2 seconds ago. We can never communicate with each other “at the same time”. Or
we never exist in each other’s world “at the same time” – we can only see others in their past &
be seen in their future. When we communicate with people on the other side of the Earth, the
delay is only a detectable split second. Even when we communicate with the people in the
same room, there is also an undetectable time delay.
In our normal experience in life, we could not feel the time lags. In our mind, we have this
“now” concept. That is everything in this Universe exist with us “at the same time” – or we exist
in the horizontal slice of Space-Time. However, everything else we are experiencing now are all
from the past - along the backward cone shape slice of Space-Time. The galaxies we see are
from millions or billions of years ago. The Sun we see is 8 plus minutes from the past. Even the
computer screen we see is from a tiny split seconds ago. Nothing in our experience is in real
time. All distance between two objects is measured along the backward cone shape slice of
Space-Time. To an observer, time is the change from one backward cone shape slice of SpaceTime to another, and not from one horizontal slice of Space-Time to another. Objects on the
horizontal slice of Space-Time are merely objects at the same age (from the beginning of time).
The horizontal slice of Space-Time is meaningless to any observer.
3. The cosmic microwave background:
At any time & location, the observer could only see as far back as when the photons were
released near the beginning of the Universe - the cosmic microwave background. Beyond that is
an opaque sphere of the early Universe.
The cosmic microwave background is the Universe near the beginning of time, and when the
Universe is cooled down enough to allow photons to be released. It is often described as
“leftover” thermal radiation from the time of recombination in Big Bang cosmology. This gives
the impression that when we look back in time, somehow we see our part of the Universe in
the past.
The Moon we see now is a part of the Universe couple of seconds in the past. The Sun we see
now is a part of the Universe eight minutes or so in the past. The first galaxy we see now is a
part of the Universe 13.4 billion years in the past. Those are the past of other part of the
Universe – not our past. The same is true for the cosmic microwave background, which is the
past of other part of the Universe – not our past. As time moves on, every moment the cosmic
microwave background will present a different part of the Universe.
4. The Subjective Universe:
When an observer at our location looked back in time say 5 billion years ago, Galaxy GN-z11
(the first galaxy we can see at current time) did not exist or not visible to the observer. It was
still in the opaque sphere behind the cosmic microwave background. When observer at our
location looked back in time say 10 billion years ago, both Galaxy GN-z11 & B did not exist in
their Visible Universe. They were still in the opaque sphere behind the cosmic microwave
background.
It seems as time moves on space & energy/material are released into our Visible Universe from
the opaque sphere behind the cosmic microwave background. 10 billion years ago, Galaxy C
was near the expanding sphere. 5 billion years ago, it was Galaxy B near the expanding sphere.
At that time, Galaxy C would be far away from the expanding sphere & with a much slower
moving away speed. Today, it is Galaxy GN-z11 near the expanding sphere. At that time, Galaxy
B & C would be far away from the expanding sphere & with a much slower moving away speed.
We would like to think that we are objective. Unfortunately, we can only be subjective. Our
observation tells us that the objects in the Universe are moving away from us. In addition, the
moving away speed of an object is generally proportional to the object’s distance from us. This
had gave us the impression that the space must be expanding. However, the observation of
objects moving away with the speed proportionally to their distance is looking back in time – or
along the backward cone slice of Space-Time. The interpretation of expanding space is based on
everything happens “at the same time” or along the horizontal slice of Space-Time. As
discussed, the horizontal slice of Space-Time is meaningless to any observer.
In the Big Bang Cosmology, the space expanded at almost infinite rate at the beginning of time.
This is to think that the expansion was from one horizontal slice of Space-Time to another. As
discussed before, the horizontal slice of Space-Time is meaningless to any observer.
From our prospective, the cosmic microwave background & the opaque sphere behind it is
expanding with time. As the sphere expands, it leaves or releases space, energy/material into
our Visible Universe. Objects near the sphere - such as Galaxy GN-z11, were objects just
released into our Visible Universe. Their observed moving away speed are very fast. Objects
closer to us – such as Galaxy B & C, were objects that had been inside our Visible Universe for
some times. Their moving away speed are much slower. In a way, the moving away speed of all
objects would have to slow down to allow new objects to be released into our Visible Universe.
“The moving away speed of an object is generally proportional to the object’s distance from us”
has nothing to do with the expansion of space or the slowing down of space expansion.
Moreover, we could consider the Space-Time, the Universe in its totality as a database, and the
observers are functioned as applications. At any point & time, the Universe is putting out a
show for the observer & with the observer in the center & the sphere expanding out at speed
of light, leaving behind space, material/energy & time. Endless shows are being performed
simultaneously at different location/time. Outside every sphere, there is the same infinitely
dense dot in the middle of nothingness.
Lo-Li Chih
Rewrote February 2017