Our universe is an intriguing place and over several thousand years of technological progress,
we have gradually learned a great deal about it. But still, there are some theories that
only make us want to know more about what’s really out there… for better, or worse.
This is Unveiled, and today we’re taking a
closer look at four theories about the universe that will stop you sleeping.
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For theory number one, we enter the Braneworld. Naturally, it is difficult to imagine something
as big and, well, universal as the universe coming to an end… but scientists believe that
it will happen, eventually. To figure out how and when and why, some models argue that we
need to look back in time… back to the very first moments when the universe began. We know that it
was about 13.8 billion years ago that the universe came into existence. Space and time emerged from
an incredibly tiny and dense point, for what’s usually called the Big Bang. Just after this,
the universe rapidly expanded in all directions and eventually settled into what we know today.
Altogether, this is what scientists call the standard “inflation” model… although,
while its basic proposal is accepted by most physicists,
the detailed mechanism responsible for inflation is unknown. And that’s a bit of a problem. So,
in 2001, the physicists Paul Steinhardt, Justin Khoury, Neil Turok, and Burt Ovrut
suggested a radical alternative theory called ekpyrotic cosmology. Ekpyrotic cosmology says
there is no beginning of time, like there is in the Big Bang. Instead, it says that
there’s an additional spatial dimension to our three-dimensional universe known as the “bulk”.
The bulk is both incredibly massive and extremely intricate, all at once. This model says that our
universe isn’t alone; it exists on one of at least two probably four-dimensional membranes
(or sheets) that are floating within the bulk; a bizarre, probably five-dimensional space. Back
in the here and now, though, in our universe’s future, we do know (or suspect) that galaxies will
eventually drift so far apart from one another (thanks to inflation) that the light from one will
never reach another. In this way, stars will grow old and die, and our universe is set to one day
become a cold and empty void. But, although this may sound like a pretty brutal ending for reality,
it’s actually the beginning of the next universe according to brane cosmology. This is what happens
when one cold and empty brane in the bulk, given enough time, collides with another. According to
braneworld advocates, this collision could then generate enough energy to make an entirely new
universe, in an endlessly repeating cycle. The fresh branes continue in this way forever more.
Emerging, evolving, dying… but also moving closer and closer together, over probably trillions of
years, and eventually crashing into (and through) one another with energy enough to birth yet more
brane universes. Instead of the Big Bang, there is what’s come to be known as a Big Splat. Over
and over again. Whether it’s all quite dark and hopeless, or majestic and hopeful - you decide!
From the outset, by comparison, there’s very little debate over the apparent hopelessness
of theory number two; false vacuum decay. Here, we’re first dealing with some of the
most fundamental principles in science. The laws of physics tell us that lower
energy equals stability… and that all systems (and particles) then try to become stable by
moving toward the lowest possible energy state, also known as the vacuum state.
It’s heavy physics, but when it comes to terrifying universe theories as a whole,
that journey to the vacuum state is what’s key - because when it isn’t made,
we have a problem. Physicists believe that the Higgs Field - a crucial kind of energy
plane that gives mass to particles, and that also features throughout the universe - isn’t
at its true vacuum state. The Higgs field is, then, most likely operating in a false vacuum.
Much like a ball that rolls down from the peak of a hill and lands in a valley while remaining
unaware that there is also an even lower valley to fall down into nearby… the Higgs field is in
a state that may appear stable but actually is not the lowest energy state possible.
And this is potentially quite bad. Because that false vacuum state could, in theory,
change at any second… and when it does, the Higgs field could effectively destroy
the entire universe, by default. Everything we’ve ever known (and ever could know) gone,
simply and efficiently. All it would need is for any one point in space to collapse into that
lower energy state - to move from false to true vacuum. This would then result in a vacuum bubble,
and predictions are that that bubble would then expand outward from that point at the
speed of light, obliterating everything that it reaches. But the scariest part is that,
with the vacuum expanding at lightspeed (i.e., with the universe decaying at lightspeed) we
would have very little warning as to what was about to happen to us here, on Earth,
until it reached us. So, one moment we’re living out our lives, the next we’ve been physically
rewritten out of all reality. It could happen now. Or now. Or… now. We just can never know.
Thankfully, if you still exist to watch this video, then the universe does at least remain
stable at this very moment. So, let’s move on. And it’s not like the instantaneous disintegration of
everything is even all there is to worry about, anyway. Enter theory number three;
the dark forest. Now, this one isn’t quite so all-encompassing in its depiction of the
end times, but it is literally built on deep set cosmological paranoia.
We know the universe is a large place and that it hosts a great number of habitable
planets. But then, as the Fermi Paradox asks, why is it that we’re yet to hear from any other
alien civilization? Broadly, the dark forest hypothesis suggests that the most intelligent
alien groups are also deliberately avoiding contact. Originally outlined in Liu Cixin’s
sci-fi novel, “The Dark Forest”, the theory contemplates the possibility that any alien
life would have to expand in a universe with limited resources. And, therefore,
this could eventually mean interstellar conflict bred by that need for resources. Competition and
rivalry between various alien civilizations, potentially to lethal ends. To avoid this,
then, the safest course of action could be to wipe out any other lifeform before
the same could be done to them. Or, to dodge every other lifeform, at all costs.
Generally, it’s in this way that the universe is likened to a dark forest. In this view,
every possible alien civilization is a stealthy hunter, prowling silently through the forest
itself (i.e., through the universe) and trying their best to be careful… because they understand
that they may not be the only hunter in the forest (or, in the universe). If life in any
other form were to be stumbled upon, then it’s kill or be killed. Open fire and eliminate it,
or find yourself wiped out first - if you delay. On one level, it turns reality into something
like an all-action video game… on another, it means that we’re always one wrong move
away from instant doom. Furthermore, it’s one potential explanation for the so-called great
silence - a term closely linked to the Fermi Paradox - as, here, the silence of the stars
is explained away because everything is either already dead, or too afraid to make a sound.
But, let’s end on something a little more uplifting, shall we? Theory number four may
still rob you of sleep, but only because its implications are so wide and profound that
it’s really difficult to imagine in the first place; quantum immortality. Here, we can start
with Erwin Schrodinger and his most well-known thought exercise. Place a living cat into a
sealed box with a hammer, a vial of poisonous gas, and a very small amount of radioactive substance.
If even a single atom of the radioactive substance decays, a relay mechanism will release the hammer,
which will then break the vial of gas and cause the cat to die. Simple, right? Except,
it isn’t. Not exactly. Because, according to the Copenhagen interpretation of quantum mechanics,
Schrodinger’s cat could be both alive and dead until someone looked into the box. This meant that
the observer could (and would) directly influence the cat’s final outcome, in that specific example.
Observation was key. And the same can be applied to the universe at large. As with Schrodinger’s
cat, particles can exist in multiple states until they are measured - or seen. Once this happens,
the particle is said to collapse into a specific state among the many it originally had.
But, while that’s all very interesting… how does it equal living forever? Well, in a many-worlds
multiverse - the increasingly popular model for reality in which there are other universes beyond
this one - an interesting scenario pops up. Here, every time you open the box to check on the cat,
reality splits. In one universe, the cat dies and in another, it lives. If we then repeat
the experiment a billion times - a trillion times, even - in one universe, you inevitably
get a living and essentially immortal cat. No matter what happens, it never dies, despite all
the other multiverse versions succumbing to the poison. While we cannot ever be sure which of
the versions of the cat is truly immortal, the many-worlds interpretation of quantum mechanics
argues that its immortality is guaranteed… as at least one incarnation of its consciousness
would always (and forever) branch out to follow whatever path doesn’t lead to its death. And so,
while it remains a controversial subject, quantum immortality is a tantalizing theory and one
that perhaps leaves us with more questions than answers. It suggests that for everyone and thing,
there’s an inherent existential crisis wrapped up in the consequences of every single decision made.
For now, in general, there is still much more to the universe that we have yet to
fully comprehend. There are countless breathtaking (and at times terrifying)
possibilities on offer. But the braneworld, vacuum decay, the dark forest, and quantum
immortality… those are four universe theories, in particular, that will stop you sleeping.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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