Hey viewers do you know it is fifty years since the first episode of Doctor Who was
broadcast.
And so we're gonna have a special themed Doctor Who week here on Head Squeeze and I've been
asked, really, quite a Doctor Who(ish) sorta question which is what is a parallel universe?
Well, most of us find ourselves experiencing the occasional twinge of frustration what
an imperfect world we live in.
Wouldn't the sky look better if it was purple instead of blue?
Why hasn't Simon Cowell been publicly executed in front of a baying mob?
And what if you'd been brave enough to ask Lindsey Beardmore out on a date when you were
16, instead of just hanging up the phone when she answered?
Yet according to some physicists -- and a considerably larger group of science fiction
authors -- in another, parallel universe all of these errors have been corrected.
In this alternate reality you are happily married to your first childhood crush, watching
a live broadcast of the X-Factor supremo cowering before a firing squad under a lilac sunset.
But is it just wishful thinking?
If you believe that space is infinitely big then it follows that if you travel far enough,
you'll find another planet just like ours.
Or, if you travel even further, one where a single critical thing is different: like
Jeremy Clarkson not having a face like Buzz Lightyear's grandma.
This is the most basic view of parallel universes: one based on the assumption that, outside
our own universe, there are an infinite number of others.
It may or may not exist, make your own mind up.
Because however our technology advances, it will be impossible to prove or disprove it.
That's because we're inside the Hubble volume of our own universe, the vast spherical region
of the light moving outwards from the big bang.
And which, because the universe is still expanding, we cannot see beyond.
Because however enormous our universe is, it's not big enough to give us another sun,
another earth and, thankfully, another Richard Hammond.
But maybe we don't have to travel so far to find a parallel universe.
Maybe we're surrounded by them, all the time.
Maybe, indeed, we're living in one right now.
Welcome to the brain-melting 'many worlds' interpretation of quantum mechanics.
We'd have to spend several years getting higher degrees to be able to understand this fully,
but in the simplest terms possible this is the idea that every possible outcome of every
possible variable effectively branches into a different parallel within a single 'multiverse'.
The idea sprung from the Schrödinger's Cat paradox that highlights the fundamental oddness
of quantum states.
That being the idea that a cat trapped inside a box with a device that can kill it at random
exists in both alive and dead states simultaneously from the point of an outside observer.
According to the Many Worlds interpretation which is part of mainstream quantum physics,
not just science fiction, where there are a range of possible outcomes, each of these
corresponds to a different universe.
So in one you had eggs for your breakfast, in another you had porridge.
And in a third you opted instead to stay in bed with a bottle of vodka.
But, as it's only these outcomes that are changing, not the physical rules or properties
of the universe itself, they can all exist in the same hubble volume.
The only problem being, despite Hollywood's best efforts, Bill and Ted's Bogus Journey
stands as a highlight of the genre, there's still no way to visit any of these parallel
realities.
Well, other than accepting that everything you do in this one is steering you on one
path through this vast maze of possibilities.
To your other self, you are the parallel universe.
Not complicated enough?
Then try what renowned cosmologist Max Tegmark has postulated as the ultimate parallel universe,
one built around a different set of physics from our own.
His mathematical universe hypothesis is based around the argument that our physical reality
is a mathematical structure, and that other mathematical structures, leading to different
sets of physical rules, are equally valid.
Therefore, somewhere, the sky is indeed purple and rain falls upwards.
But The Young Ones still won't be funny.
Click on my face to watch my favourite films on Head Squeeze, or click on any of the other
presenters faces to watch their favourite films.
Watch mine first.