The Multiverse #2: Infinite Improbability

In my last post I covered why I don’t like the many worlds interpretation of quantum mechanics that is required for the existence of an alternate universe.  In this post, I would like to drive home just how ridiculously improbable the interaction with that universe is.

I have established that every second (or every period of time shorter than a second, for that matter) an infinite number of alternate universes are created for every atom in existence.  Thus there are a constantly increasing infinite number of alternate universes.

This leads to an interesting point: the likelihood of finding any one universe is literally infinitely small.  Imagine if you roll a die: there are six faces, so there is a 1/6 chance of any one face landing up.  Imagine now that you roll a die with an infinite number of faces.  Now what is the chance of a specific face landing up?  One over infinity.  Which, in mathematics, is treated as zero.  Of course, it isn’t actually zero.  One side HAS to show up.  But it’s a number so small it’s hard to imagine.

So it is already infinitely unlikely that any particular universe is found.  But consider the other ridiculous coincidences: the technology in the other universe is slightly better, but all of the people in this generation have the same DNA and same family tree, but a divergence is beginning in this generation with people marrying different people and sometimes having kids instead of being barren, etc.  To find a universe that meets those kinds of parameters is even more unlikely that the previously established one-over-infinity number.  Yikes.

So how did Walter find this universe through the window?  It stands to reason that, since he was dedicated to improving the well-being of mankind, he would want a universe that was slightly ahead technologically (not too much, or else he would not be able to understand what he was seeing).  It also stands to reason that he would want to view a universe in which he is able to recognize himself working in the same lab.  So his motivation in looking for what he found makes sense.

But how did he actually find it?  There are an infinite number of universes to browse through.  You know that impatient feeling you get when you search for something on Google and you don’t find it on the first page of results?  What if there were an infinite number of pages of results and you had to look through them all, and, oh-by-the-way, the number of results was increasingly exponentially every fraction of a second.  Yikes.

Ultimately, I forgive the show for all of this.  Because it’s fun to think about how some things could have been slightly different, and the alternate universe is a plot device that provides that.  So I suspend my disbelief.

The Multiverse #1: Many Worlds

Understanding Fringe requires an understanding of quantum physics.  I'm not sure if the writers realize that.

The over-arching plot of the show is that Walter crossed into an alternate universe that closely resembled our own and now they are at war with us.  The amount of suspension-of-disbelief that this requires is staggering.

First, the presence of alternate universes is dependent on the many worlds interpretation of quantum mechanics.  There is no evidence that this is an incorrect interpretation.  But it is unsatisfying and not generally accepted.  The generally accepted interpretation is the Copenhagen Interpretation.  There is no evidence that the latter interpretation is the objective reality...mostly because the later interpretation denies the existence of an objective reality, but still.

The difference between the two views can be illustrated simply with Schroedinger's Cat.  Imagine a cat placed into a box with a poison vial that will release the poison as soon as a radioactive decay occurs.  The Copenhagen interpretation: Since, for a radioactive decay to occur, the waveform of the nucleus needs to collapse, and only an observation can collapse a wave function, as long as the box is closed the cat exists in an indeterminate state; it is both alive and dead at the same time.  The many worlds interpretation: the wave form collapses at every time that is probabilistically possible.  Each possibility creates another universe.  In some universes the cat is alive, in others it is dead.

Though at first blush the Copenhagen interpretation seems deeply unsatisfying it passes the Occam's Razor test: it is the simplest explanation that fits the facts.  The more I learn about quantum mechanics, the more I like that.  I find the many worlds interpretation appalling.  Consider radioactive decay as an example.  The decay of a radioactive isotope has a finite probability of occurring at any moment.  At every moment it can decay, and in this interpretation it does and in doing so it creates a new universe.  Time, though uncertain, is not quantized like energy is.  That means that, just in observing the decay of one atom over one second, and infinite number of universes have been created.  There are about 10^80 atoms in the universe, and each one results in the creation of an infinite number of new universes every second.  That means that every second, 10^80*infinity new universes are created.  Can you see now why this feels a little absurd?

But if we assume that the many worlds interpretation is correct, what are the chances that we would find a parallel universe like that which is depicted in Fringe?  I'll cover that next time.