Download MC_Paper2_Multiverse

Chang 1
Mark Chang
Math 89S
Professor Hubert Bray
New Copernican Revolution? (Universe or Multiverse)
Chang 2
Background
The beginning of the universe is a mystery that leaves us with many questions to this day.
Our universe, all of space and time with everything within, is estimated to be 13.7 billion years
old, but what if our universe is just one of many universes that form the multiverse? Multiverse
is a theory that states the existence of infinite number of universes, including the universe of our
own. These universes within the multiverse are called “parallel universes” and together includes
everything of existence. Although we may never be capable of observing the universes other
than our own, there are various proven theories of physics that predict the existence of multiple
universes. For example, the universe spreads infinitely in a flat space-time, and it is inevitable for
there to be repetition because the number of ways particles can be arranged is limited compared
to the unlimited universe. Perhaps in some universe there is another you that is identical but
makes some other decisions than you have made in this universe. Our observable universe is
limited to the 13.7 billion years that light has been able to travel through space-time. Universes
that exist beyond our universe could be seen as its own universe.
Quantum Mechanics (Many-Worlds Interpretation)
You are faced with the decision to go right or left, and you decide to take a right.
According to the quantum theories of multiverse, both of these possible outcomes will occur in
different universes by the formation of two daughter universes where one version of you will
take a left and the other will take a right. Many-Worlds Interpretation, the theory derived from
Chang 3
quantum mechanics, observes the world in terms of probability, and the mathematics gone into
these theories come to prove the existence of all the possible outcomes within different
universes. Perhaps quantum mechanics contains proof that we were wrong about the single
unfolding history and show how all possible quantum outcomes are present in different
universes.
I.
Hugh Everett – Measurement Problem
To understand how the multiverse theory originated, there needs to be an understanding
of how the measurement problem was interpreted by High Everett. The measurement problem in
quantum mechanics originates from the question on whether or how wave function collapse
happens. Wave function simply is the collection of all the possible configurations and states that
a particle takes. According to the Schrödinger equation in quantum mechanics, the wave function
changes as a linear superposition of differing states. In other words, an elementary particle can
be found in a superposition of two or more different states. However, when scientists observe
these particles, there is only one observable superposition of the element and not the various
combinations of the different states that the element can take. Therefore, the main question that
is derived from this problem is how is our unique experience of the world chosen from the
various alternatives there are in the superposed quantum world.
In order to solve the measurement problem, Everett asked what would happen if the act
of measurement never interrupted the wave function. Without the interruptions of measurement,
all the possible different states in the superposition will exist. Under these circumstances, the
wave function will create different branches that contain all the alternatives of every outcome of
Chang 4
the particle’s superposition. Each branch created will have its unique observer, and the different
branches will take on different futures, which will exist in different universes.
Figure 1
As shown in figure 1, splitting occurs as there are possible outcomes that result from the
observation of the particle, and this is then observed as one state when observed. Splitting
happens successively, creating even more branches of different particle states. However,
particles are observed as one of the infinite branches that are formed, and the other possible
branches are experienced in another universe.
II.
Daughter Universes – Schrödinger’s Cat Paradox
The Schrödinger’s Cat Paradox is a theoretical experiment where a cat was trapped in a
chamber with a radioactive atom. The cat is classified as both alive and dead until the cat’s
condition is observed directly, because it is ambiguous whether or not the atom placed in the
Chang 5
chamber has decayed and emitted radiation.
Figure 2
As shown through figure 2, when the poison from the decaying atom is released into the
chamber, the cat is simultaneously alive and dead. According to the Many-Worlds Interpretations
the both states – dead or alive – exist decoherent from each other. According to quantum
decoherence, the two states of dead and alive will not interact with each other, but these two
states will exist in different universes. We will only experience one of the two states of the cat,
and this creates the splitting mentioned in the previous section of this essay.
Chang 6
Figure 3
Figure 3 shows how there are different outcomes for the different states of the
superposition of the particles. This diagram helps to understand how there is no interaction
between the two states in consistent histories. The different possible outcomes create the rise to
daughter universes, where in one the cat is alive and the other the cat is dead. These decoherent
outcomes will form separate universes.
Possible Observational Evidence for Multiverse
Although to this day, it seems as though finding observational data for multiverse is
farfetched, there is a possibility in the future that one will discover evidence other than mere
theories to prove its existence. According to the anthropic principle, observations of a certain
universe is limited to those who are compatible with the conscious people that see it. Each
universe has its own physical laws, so it is impossible for us to observe these other universes
with different fundamental laws.
However, there are theorists who claim that collisions between different universes
perhaps may lead to gravitational waves that leave an observational signal on our observable
universe. Currently, by using the Wilkinson Microwave Anisotropy Probe (WMAP), scientists
are trying to measure any changes on the cosmic microwave background (CMB) that results
from the collision of another universe and ours. There has been no observable evidence found to
this day, but there are efforts in proving the theory of multiverse.
Chang 7
Works Cited
https://en.wikipedia.org/wiki/Anthropic_principle
http://www.pbs.org/wgbh/nova/blogs/physics/2015/05/a-new-way-to-detect-bubbleuniverse-collisions/
https://en.wikipedia.org/wiki/Schrödinger%27s_cat
https://en.wikipedia.org/wiki/Measurement_problem
http://www.scientificamerican.com/article/hugh-everett-biography/
https://www.youtube.com/watch?v=KNwKPfOKipk
https://en.wikipedia.org/wiki/Multiverse#Max_Tegmark.27s_four_levels
http://www.space.com/18811-multiple-universes-5-theories.html
http://plato.stanford.edu/entries/qm-manyworlds/#4.1
https://en.wikipedia.org/wiki/Many-worlds_interpretation
Chang 8