Monday, April 29, 2013

How Many Universes Are There In a Multiverse?

Andrei Linde is Professor of Physics at Stanford University and the author of several important theories, including the inflationary universe theory, the inflationary multiverse theory and the theory of eternal inflation. These theories taken together envisage a multiverse with an eternally growing fractal structure in which universes continuously arise, with different laws of low energy physics operating in each of them.

In a 2009 paper (1) Linde and Vanchurin attempted to calculate how many universes there are in a multiverse. The initial calculation came to 10^10^10^7, a very large number and one which they admit could be wrong by many orders of magnitude. But they quickly point out that a multiverse has no meaning without an observer, if correctly viewed by quantum physics. 

“One of the implications of this result is that one can talk about the evolution of the universe only with respect to an observer. In the limit when the mass of the observer vanishes, the rest of the universe freezes in time. In this sense, the number of distinct observable histories of the universe is bounded from above by the total number of histories that can be recorded by a given observer. And this number is finite.”

Their calculation takes into account the total amount of information that can possibly be absorbed by a human brain during its lifetime, which they deem to be about 10^16 bits, “which means that a typical human brain can have about 10^10^16 different configurations, which means that a human observer may distinguish no more than 10^10^16 different universes.” From this number they hope to calculate the probability of a universe in which the laws of physics would allow intelligent life to evolve, the so-called anthropic principle.

So how many parallel universes are there in a multiverse? As many as your brain can fathom.

Wednesday, April 24, 2013

Quantum Physicists, Consciousness, God

With the introduction of relativity theory and quantum mechanics Newton’s mechanical view of the universe came to an end. Instead of the classical deterministic view of existence now developed an image of a universe that exists as a set of possible outcomes, a probability distribution. Heisenberg’s Uncertainty Principle states that one cannot know both the exact position of a particle and its momentum at the same time. This led to the Copenhagen interpretation of quantum mechanics which states that an object acts as both a wave and a particle in a set of probability waves. The act of measurement by an observer causes the “collapse” of a set of possibilities into one randomly chosen one which becomes physical “reality.”

The question of what constitutes an observer has plagued quantum mechanics from the beginning. Schrödinger' cat experiment in which a cat in a box can be both alive and dead at the same time (a quantum superposition) until an observer opens the box was complicated by the realization that the observer may also be in a quantum superposition and would require yet another observer and so on ad infinitum. If the entire universe is a quantum universe then there needs to be an ultimate consciousness outside of the universe to bring it into existence.

Thursday, April 4, 2013

How Many Scientists Believe in God?

The question "Do you believe in God?" has a different meaning for each individual. God can be a personal God, a God of a specific religion, a God who created the universe and its laws but who did nothing after that, and so on. Let’s begin with statistics asking the question, "Do you believe in a personal God?"

The US psychologist James H. Leuba in his survey of 1914 found that 58% of 1,000 randomly selected US scientists expressed disbelief or doubt in the existence of a personal God. This figure rose to nearly 70% among the 400 "greater" scientists within his sample (1). Leuba repeated his survey 20 years later and found that these percentages among “greater” scientists had increased to 85%. (2). In 1998 Larson and Witham repeated Leuba’s study, using the term “greater” scientists to mean those who are members of the National Academy of Science. The results are shown in