As we gaze up into the vastness of outer space, we are reminded of just how small we are in
the grand scheme of the universe.
We’ve only explored just a small fraction of the universe, and even physicists know
that there’s more that we don’t understand about outer space than what we’ve figured
out.
A new paper that was published in the Journal of High-Energy Physics in March twenty-twenty,
called “Nothing Really Matters” - great title - is why scientists are freaking out
over “bubbles of nothing” that eat spacetime.
Marjorie Schillo is one of the authors of this amazing new study.
She is a researcher at Sweden’s Uppsala University in their Department of Physics
and Astronomy where she studies theoretical physics.
Physics is the study of matter, energy and the interactions between them, but it’s
a much more exciting science than that description makes it sound.
Physicists try to answer big questions like “How did the universe begin?” or “What
are the basic building blocks of the universe”, or even “How will the universe end?”
Theoretical physics and math may not sound very cool, but some of the biggest rock stars
of science have come out of this field.
Isaac Newton invented calculus and discovered gravitation; Albert Einstein came up with
the Theory of Relativity, among many other important discoveries, and Stephen Hawking
was one of the most recognizable scientists of all time.
Many physicists use experiments to test their theories, but theoretical physics is different
in that they use math to attempt to answer these big questions in areas where scientists
can’t yet perform experiments.
Marjorie Schillo and her colleagues have spent years studying the phenomenon of “spacetime
decay”, trying to answer the big questions about how the universe might end.
This newest paper explores one possible answer - a bubble of nothing that eats spacetime.
As she explains it: “A bubble of nothing describes a possible channel for universe
destruction; in that the bubble of nothing expands and can ‘eat’ all of spacetime,
converting it into ‘nothing’.”
Umm...OK.
Translated from “science” to plain English, what she and her team of researchers at the
University of Uppsala in Sweden are saying is that a bubble of nothing that eats spacetime
is just one of the theoretically possible ways that our universe could be destroyed.
To be honest, that doesn’t sound much better...
There’s plenty of things in the universe worth freaking out about - black holes, supernovas,
even rogue asteroids.
But could a bubble of nothingness really eat all of space and time, devouring the universe
and ending life as we know it?
Is the universe really eating itself from the inside out?
The idea of a “bubble of nothingness” in space isn’t a new one.
In nineteen-eighty-two, theoretical physicist Edward Witten first posited that the universe
could be devouring itself when he wrote about a hole that “spontaneously forms in space
and rapidly expands to infinity, pushing to infinity anything it may meet.”
To understand these bubbles of nothing, we need to wrap our heads around vacuums.
No, not that kind of vacuum…In physics, a vacuum is an empty space devoid of all matter.
In Quantum Field Theory, the theory that connects quantum physics with spacetime, a vacuum is
the lowest possible energy state.
More ‘excited’ or higher-energy quantum states tend to decay very quickly into lower
energy states as they give off energy.
Since a vacuum doesn’t have a lower energy state to decay to, vacuums are relatively
stable.
It’s commonly accepted that outer space is a vacuum, so the universe should be pretty
stable, right?
Well, it’s not quite that simple.
Outer space certainly isn’t devoid of matter - it’s full of stars, planets, particles
and, umm ... people!
It’s the extremely low density of the matter that’s important - between the planets in
our solar system there is an average of five atoms per cubic centimeter.
In interstellar space - between the stars and molecular clouds - there is only one atom
per cubic centimeter, and in intergalactic space - between galaxies - there’s one-hundred
times less matter per cubic centimeter than in interstellar space.
This extremely low density of matter, combined with the incredibly low pressure in space,
creates an almost perfect vacuum ... but not quite.
Quantum theory actually suggests that a perfect vacuum is impossible, since energy fluctuations,
known as ‘virtual particles’ happen even in empty space.
In the nineteen-seventies, some Russian physicists were the first to suggest that there could
be a middle ground between a stable vacuum and an unstable non-vacuum.
These ‘false vacuums’ stay in a metastable, or semi-stable, state for an incredibly long
time before decaying, giving them the illusion of being a stable vacuum when in fact they
are not.
The quantum force field that pervades the universe and gives all matter its mass is
called the Higgs Field, and it was first detected by the Large Hadron Collider at CERN.
It would take a whole other video to even begin to explain the Higgs field, but as far
as understanding bubbles of nothing is concerned, here’s why it matters: Recent research into
the Higgs Field suggests that we may actually be living in a false vacuum after all.
If that’s true, our university is not the safe and stable place we once thought - it’s
actually unstable, and this is where the bubbles of nothing have their opportunity.
A bubble of nothing is one of the ways that a false vacuum could theoretically decay to
a more stable energy state.
If a bubble of nothing were to form within the apparently false vacuum that is our universe,
it would start out as a small hole in the fabric of our reality.
The tiny space of emptiness would then quickly begin to expand outward, picking up speed
as it expands until it’s growing at the speed of light.
As it grows, the bubble of nothing would eat all of the matter it encounters, gobbling
up everything in its path and converting all matter into nothingness until the universe
is erased completely.
So what are these ‘bubbles of nothing’ exactly?
As you can imagine, describing ‘nothing’ is not exactly easy.
It’s tempting to compare a bubble of nothing to another phenomenon of ‘nothingness’
that we know exists in our universe - black holes - but a bubble of nothing couldn’t
be more different from a black hole.
A black hole is an area of such intense gravity that it sucks anything, including light, into
its center.
A bubble of nothing, on the other hand, expands outward and devours everything in its path,
turning anything it encounters into more nothing.
If you threw something into a black hole, it would disappear forever, and we would have
no idea what happened to it once it passed through the black hole, since we’ve never
seen the inside of one.
But if you could throw an object into a bubble of nothing, it would bounce right back out
- for all intents and purposes, it would have hit the edge of the universe.
A bubble of nothing is not the only kind of bubble that might exist in space.
A spacetime bubble is any area of space that has different properties inside the bubble
than the space outside the bubble.
For example, some bubbles could have different strengths of dark energy inside and out.
Bubbles of nothing have no interior at all - they are totally empty inside.
As the bubble grows, it ‘eats’ all the regular matter it encounters and converts
it to ‘nothing’.
So how could a bubble of nothing form in the first place?
To understand how bubbles of nothing might form, we have to dive into string theory a
bit.
Don’t worry, it won’t be that bad…
String theory attempts to tie together the two most basic laws of physics: the theory
of general relativity, or gravity - with quantum physics, the study of the very smallest particles
that make up the universe.
String theory also attempts to unify the four forces in the universe - electromagnetic force,
strong nuclear force, weak nuclear force and gravity - into one model.
String theory may indeed turn out to be the “theory of everything”, but it’s important
to know that String Theory relies on a lot of assumptions about particles and forces
that can’t yet be proven.
Don’t worry, scientists aren’t just blindly guessing - these assumptions are all based
on solid scientific evidence and complex mathematical equations - needless to say, you’d need
a PhD in physics to truly understand the intricacies of String Theory.
The biggest problem with string theory is that it requires more than the four observable
dimensions to work.
We can easily observe the three dimensions of space and the extra dimension of time,
but for string theory to work there must be at least a few other dimensions that are invisible
to us.
As cool as the idea of hidden dimensions sounds, it’s not the parallel universe you might
be picturing - you know, the one where you’re you, but with money and power and good looks
and….*coughs* anyway…
Physicists theorize that these extra dimensions could actually be incredibly tiny and curled
up below the observable scale, making them too small for us to see them.
Scientists can still account for these extra dimensions mathematically, but we have yet
to actually prove they exist.
For some reason, bubbles of nothing can’t form in four dimensional spacetime - don’t
ask us to explain the math behind why, it would take years!
But scientists believe that they can form in stringy multidimensional spacetime like
the spacetime described by string theory.
In fact, one model of stringy space time, the Kaluza-Klein model, states that across
infinite space the probability of a bubble of nothing destroying everything is one-hundred
percent.
So, should we be concerned about bubbles of nothing appearing in space and devouring the
entire universe?
Apparently not.
Most scientists believe that since the universe hasn’t eaten itself in the thirteen billion
years since the Big Bang, it’s an unlikely scenario.
One Czech string theorist named Lubos Motl went so far as to say that we should use the
idea of bubbles of nothing to rule out certain descriptions of our universe, since if it
was going to happen it would have happened by now.
That doesn’t totally negate the possibility, but it’s also reassuring to know that scientists
consider this to be something to rectify, not something to agonize over.
We’re not sure exactly how scientists would suggest that we fix a bubble of nothing, but
it’s nice to know that they at least think we can...right?
Perhaps most importantly, physicists think that studying these bubbles of nothingness
can give us important clues about the very beginnings of our universe.
The study authors think that the mathematical models used to describe a bubble of nothing
could also be used to model the birth and expansion of the universe.
Marjorie Schillo, the researcher we met at the beginning of this video, has said “It
would be interesting to work out under what conditions an observer could ‘ride’ on
the bubble of nothing and see a universe that is similar to the one we live in.
Because the bubble expands, such an observer would see an expanding universe.”
Riding on a bubble of nothing may be a bit far-fetched, but this research is important
for helping us understand our universe, according to the researchers who authored the “Nothing
Really Matters” paper.
They argue that we can learn important lessons from these bubbles of nothing that might help
us better connect the current best theories about fundamental building blocks of the universe
with theories about space and time, and hopefully, finally, help us finalize String Theory - the
theory of everything.
So, what are your thoughts on the bubble of nothing that eats spacetime?
Do you think we should be worried about the universe eating itself from the inside out?
Be sure and let us know in the comments!
If you thought this video was interesting, be sure and check out our other videos, like
“Astronomers Discover Mysterious Radio Signal From Another Galaxy”, or this other one
instead.
See you next time!