﻿In the popular view, space is that deep, dark, and vast abyss that exists between
the celestial bodies, objects, and structures of the cosmos, separating all from one another.
But is it truly as empty as we think it is? Or is this vacuum that spans across literally
everything and everywhere hiding something from us, something mysterious, and perhaps the most
powerful source of energy there is? Welcome to Factnomenal, and today
let’s dive into deep space, far, far away, and find out the shocking truth about Vacuum Energy.
Does the Vacuum hold the secret to the origin of the Universe?
In our recent video about the possibility of the existence of a fifth fundamental force in the
universe, we discussed how energy is carried by very minute particles called bosons. So,
if there is indeed vacuum energy, then there must be certain particles present to carry that energy,
right? That’s just simple logic! Apparently, these Vacuum Particles,
which astronomers are certain exist, have made quite an impact on the universe we know today.
Not only do they explain ‘particle-particle interaction’, but they can be traced back
to the very origin of the universe itself! Back when there was nothing, there was a vacuum.
Before the dawn of time, when the universe existed only as a singularity, space was made up of pretty
much nothing. We have explored this question in many, many videos, but this mystery always
comes back to haunt us. After its early rapid expansion, as the universe found its footing,
the expansion began to slow down... but then all of a sudden, something changed.
Six billion years after the big bang, the universe found a renewed vigor, and began expanding faster
again. But what exactly caused this, who the culprit was, and where this power came from…
no one actually knows. There have been many speculations: dark energy, dark matter,
etc., etc, etc. But maybe the actual reason behind this is something much more minute,
something deeper at the very core of the vast abyss that surrounds us: the quantum field.
The thing with the quantum field is that it is always doing something,
but we will get into the details of it a bit later. Although these oscillations are only
observable at the subatomic level, when the universe was expanding so very rapidly, the
quantum field’s tiny fluctuations must have also blown up to the scale of the observable universe.
Similarly, these mischievous particles could be behind dark energy, which accumulates in the
empty pockets of space, and creates the favorable circumstances for increasing the expansion rate of
the universe. Also interestingly, if it wasn’t for these vacuum particles and fluctuations,
the matter distribution during the rapid expansion of the universe would have most
likely been completely homogeneous. Frankly, this would have made the universe such a boring place
to live in, with every part of it looking similar to every other, and truly containing a whole lot
of perfectly spread out boring old matter doing a whole lot of nothing. To be honest,
we wouldn’t be here if that were the case. But astronomers believe that the measured
value of vacuum energy is 10¹²⁰ times less than the prediction made by Quantum Field
Theory. According to quantum field theory, the math is off the charts,
and energy generation goes beyond infinity. And with that super-duper high amount of energy,
the universe should be expanding very rapidly, at a much, much faster rate than it does. So, this is
a mystery that still needs to be uncovered. Maybe we have our numbers wrong, or maybe
vacuum particles play no role in the expansion of the universe, or maybe they don’t even exist.
To understand Vacuum particles, first, we must understand the vacuum itself.
The Shocking Truth About the Vast Nothingness of Space
Can something come from nothing? The common view of outer space among the general public is
that it is a never-ending void with occasional clusters of galaxies sprinkled here and there.
But astronomers believe that far from our reach, in deep space, where there is not
even a speck of dust present, this infinite sea of vacuum becomes almost alive, if not sentient.
But before we can look deeper into this mystical nothingness to understand what
sort of weird magic happens there, we need to understand the void itself. That is,
what in the name of Spock is… space? Quantum Field Theory describes space
as being something composed of fundamental quantum fields, with a separate field for
every particle that makes up our universe. Electrons, quarks, neutrinos, and other
fundamental particles are just the oscillations of the field with different energies. To be specific,
they all have quantum energy that exists as multiples of baseline energy. One easy way
to understand this hierarchy is as a pyramid of energy levels, where every floor of the
pyramid represents the existence of one additional particle in that quantum state.
So, the base of the pyramid would be a place with no energy at all, as this is the place for
absolutely nothing due to an absence of particles. This is what we know of as the vacuum state:
neither matter, nor any energy is present there. But apparently, this is not the case. The quantum
field is everywhere, even in those ginormous voids which span nearly endlessly between
galaxies in the dark depths of the cosmos. This quantum field gently vibrates randomly
all the time. And sometimes these vibrations are powerful enough to generate enough energy that
particles can form out of - apparently – nothing at all! These particles arising out of the
fluctuation of quantum fields are called virtual particles. So, astronomers believe that empty
space is pretty much teeming with these virtual particles, or “wiggles in the field”, as it were.
Now, if you are thinking, oh cut the crap, Virtual particles? What is this,
a video game? Is the universe a simulation? Honestly, that is a topic for another day. But,
believe it or not, as sketchy as they sound, the existence of virtual particles is explainable.
By definition, these elusive particles only exist where we can’t look, but they make their
presence felt throughout the universe. They are also the reason why Hawking Radiation happens.
Hawking radiation is the thermal radiation predicted to be spontaneously emitted by
black holes. Astronomers believe that when virtual particles pop into existence
too close to the event horizon of a black hole, the intense curvature of space-time boosts
virtual particles into becoming real particles. But real particles have mass, and this mass
has to come from the black hole itself! This process of losing mass, in the making of these
Pinocchio particles into real boys, is what makes a black hole evaporate. We can thank Hendrick
Casimir for coming up with an inspired idea to observe these virtual particles back in 1948 in
order to prove their existence. The Casimir Effect
Just like an organ pipe of a particular length only resonates with waves of certain pitches,
you can create a vessel in space by bringing two conducting plates together at a certain distance
apart. Between these two plates, virtual photons whose wavelengths fit an integral multiple of the
gap will be exclusively allowed to create a mutual attraction by the simple presence
of the vacuum. Just like two strangers left alone in a room will end up being friends,
these two plates are bound to develop feelings for each other even in an
environment of absolutely nothing. This startling phenomenon, which is now
called Casimir Effect, was first predicted in 1948 by the Dutch theoretical physicist. At the time,
he was working at Philips Research Laboratories in Eindhoven on, of all things, colloidal solutions.
We also have dubbed the force working between the two objects in this phenomenon the Casimir force.
But this is getting much too academic, and if you had come to YouTube for theoretical physics,
you’d be watching some boring channel instead of us, so let’s explain it with a bit more pizzazz...
In the old days, when classical mechanics ruled the land of physics, a Vacuum was considered a
simpler phenomenon: it was what remained if you emptied a container of all its particles
and lowered the temperature down to absolute zero. But then times changed, and quantum physics became
the new king, and with its new decree, it changed how we saw a vacuum. It made us realize that an
empty state, even at absolute zero temperature, has electromagnetic fields, and they fluctuate,
just like an empty cold heart also has some sort of feelings, fleeting as they may be.
These vacuum fluctuations are seemingly real because they have real observable consequences
that can be directly monitored in experiments on a microscopic level. For example, an atom in an
excited state will not remain there infinitely long, but will return to its ground state by
spontaneously emitting a photon. Imagine trying to hold a pencil upright on the end of your finger.
It will stay there if your hand is perfectly stable and nothing perturbs the equilibrium. But
the slightest perturbation will make the pencil fall into a more stable equilibratory position.
Similarly, vacuum fluctuations cause an excited atom to fall into its ground state.
So, these particles are created in particle and antiparticle pairs. They live only for a
short instant of time until they destroy each other, popping in and out of existence. The
higher the energy of the particle, the less time it can exist. One of the very first experiments
conducted to test the Casimir effect was in 1958, but with the development of
sophisticated devices and equipment things became more reliable in the nineties,
and a new generation of measurements began. Steve Lamoreaux was working at the University of
Washington in Seattle when he measured the Casimir force between a 4 cm diameter spherical lens and
an optical quartz plate about 2.5 cm across, both of which were coated with copper and gold.
He found that his experimental measurements agreed with theory to a 5%
accuracy. This experiment - and following ones - proved that vacuum energy is real. And this
begs an important question: Can we harness it? Harnessing Vacuum Energy
Sadly, we can’t. Oh,
you want a longer explanation? Okay... Well, you see, we talked about how the numbers are a bit
off when it comes to the amount of vacuum energy that is generated. It appears that
Quantum Field Theory’s math is a bit inflated… by a lot. The numbers are seriously so exciting
and overhyped that some pseudoscientists believe that such energy would be enough to accomplish
real sci-fi stuff like opening wormholes. The disagreement between the theoretical
and measured values of vacuum energy may be one of the greatest unsolved mysteries of physics.
Question is, viewers: are one of you a future Einstein or Hawking,
who may be able to solve this perplexing dilemma? Tell us in the comments what other mysteries of
the universe you would like us to explore next. And, as always, thanks for watching Factnomenal!