Wormholes, portals in spacetime that allow for faster-than-light travel, are a staple of science fiction. But what does the science say about them?
Host | Matthew S Williams
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Episode Notes
Wormholes, portals in spacetime that allow for faster-than-light travel, are a staple of science fiction. But what does the science say about them? In truth, scientists have been exploring the idea for over a century and there is some basis for their existence. Whether or not we'll ever be able to use them, however, is still up for debate.
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Resources
What are Wormholes?: https://www.space.com/20881-wormholes.html
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For more podcast Stories from Space with Matthew S Williams, visit: https://itspmagazine.com/stories-from-space-podcast
Are Wormholes Possible? | Stories From Space Podcast With Matthew S Williams
Episode 91 - Wormholes
[00:00:00] The authors acknowledge that this podcast was recorded on the
traditional unceded lands of the Lekwungen peoples.
Hello, and welcome back to another episode of Stories from Space. I'm your
host, Matt Williams. And today I want to address a topic that was suggested by
a friend, and which is, of course, highly relevant.
In fact, you might even say it's controversially related to the very notion of
interstellar travel and whether or not humanity will ever be able to accomplish
it. And so the topic I'm referring to is none other than wormholes, portals
through space and time, which have been predicted by the work of certain
astrophysicists, not the least of which is Albert Einstein and Nathan Rosen.
They've also become a bit of a pop culture staple, specifically with science
fiction. For many fans of classical sci fi, the concept [00:01:00] of wormholes is
certainly familiar. They constitute essentially tunnels through space time that
allow us to traverse incredible distances without the need for a warp metric.
And also, another benefit is that the transit time, we're told, would be
instantaneous. Or at the very least, very rapid, and this would allow ships
carrying crews or robotic missions to traverse dozens or perhaps hundreds or
even thousands of light years in a single jump. The concept is very familiar in
the context of science fiction.
After all, we've seen countless treatments of the idea. It has been used in
franchises ranging from Dune and Star Wars and Star Trek, arguably the two
biggest science fiction franchises of all time, to Battlestar Galactica and several
popular video games, [00:02:00] and of course, film. But what exactly does the
science say?
Are wormholes even real, and can they in fact serve as a portal allowing a
spacecraft to traverse from one point in spacetime to another? And believe it or
not, some science fiction franchises have attempted to explain how FTL travel
works in their universe. For example, in Frank Herbert's Dune, we are told that
the Navigators, a breed of mutant humans that are part of the Spacing Guild, for
which every starship, every Highliner in space depends upon, they use the
Spice, which they are constantly exposed to, hence why they've mutated, and
this gives them a limited form of Prussians, which they use to see.through space and time, effectively charting a course that will bring the ship
safely from one destination to another. [00:03:00] However, it wasn't really
until the sixth book in the series, Chapterhouse Dune, that Frank Herbert got
into any of the technical details, and they were pretty scant. Essentially, the
characters said that the Holtzman drives, as they're called, that they may in fact
include tachyons.
Which at the time of writing, which was in the mid 1980s, was a theoretical
particle that could, in theory, travel faster than light. However, that particular
theory of tachyons represented as superluminous particles has since been
debunked, and when physicists talk about tachyons today, they're referring to
tachyon fields, which have to do with imaginary mass, not FTL concepts.
However, it should be noted that Herbert, always the consummate genius, he
truncated his explanation by indicating that, yes, in the future of the Dune
universe, no one really [00:04:00] fully understood how these dry systems
work. They simply reproduced them, generation after generation, trusting in the
Holtzmann formulae.
The franchise Star Wars, of course, includes hyperspace, but no attempt is made
to explain how that works. How does a ship make the jump to hyperspace and
travel faster than the speed of light? And some of what George Lucas wrote in
the original movies that attempt to quantify how fast a ship can travel.
For example, the Millennium Falcon. Han Solo says in a early scene in the first
movie, A New Hope, that the Millennium Falcon can make 0. 5 past light speed.
And this really doesn't make any sense. Otherwise, it's treated with ambiguity
and a suspension of disbelief, basically. Star Trek, on the other hand, I did
attempt to explain warp drives and warp [00:05:00] travel, but kind of took a
scattershot approach.
And by that I mean, on the one hand, the Enterprise in the next generation. We
learned that it relies on matter antimatter annihilation. There's what's known as a
dilithium chamber, which is somehow essential to the operation of the warp
drive. And that the warp nacelles on every warp capable spacecraft, that they
have buzzard ram scoops at the front of them.
And those would be the glowing things at the front of the engines, which
apparently take in hydrogen fuel. So you've got a number of ideas here. Two of
which are based in real scientific concepts, an anti matter engine, and a
hydrogen spacecraft. And, of course, those references to the Alcubierre metric.Frequently in the show, it is mentioned that a warp shell is created by the warp
[00:06:00] core, which, of course, is what allows the Enterprise and other ships
to achieve warp speed. Then again, the original series and all the spinoffs and
follow ups, they also attempt to quantify this by saying it's possible to achieve
up to warp 10, or even more, and that time travel is possible if one were to
exceed this barrier.
Another example from popular culture in which wormholes, where there's an
attempt to explain it in scientific terms, is the sci fi horror mashup Event
Horizon. And one of the characters, known as Dr. Weir, explains the concept as
follows. Use a rotating magnetic field to focus a narrow beam of gravitons.
These, in turn, fold spacetime consistent with Weyl tensor dynamics. Until the
space time curvature becomes [00:07:00] infinitely large and you produce a
singularity. Now there's just one problem with this explanation. It's complete
and utter gobbledygook. Gravitons are much like tachyons in that they are a
theoretical particle that was proposed as a means of explaining quantum gravity.
The idea there being that if scientists could find a quantum component for
gravity, they could explain how all the fundamental forces of the universe fit
together. As I'm sure we've covered in a previous episode, the four fundamental
forces of the inverse, this being electromagnetism, weak and strong nuclear
forces, and gravity, only the first three have a quantum component.
So, Scientists still don't know how gravity fits in there on the quantum level.
They know how gravity behaves, but can't yet explain why it exists at the
quantum level. So, when Dr. Weir says you send a beam of focused gravitons
towards a point in space time, he's making things up. And, of course, [00:08:00]
that's why they call it science fiction.
Well, tensor dynamics, that's a real thing, that is a description of space time.
However, focusing gravitons on a point in space time, what is being described
there is, yes, essentially creating a miniature black hole, a. k. a. a singularity.
Now, how this would give rise to FTL travel is not clear, and it exploits a lot of
ambiguity when it comes to what we know about space time.
Black holes and the possibility of wormholes. As for the whole idea of folding
space, this is more a metaphor than anything else. Although, in theory, it does
have some merit. It's the idea that if you interpret spacetime as a two
dimensional plane, Basically, it's got a flat topology, it's got length, it's got
width, but we don't see depth per se.And if it were possible to open up a wormhole, or to assume that wormholes
naturally existed in space [00:09:00] time, that connect one point in space to
another, then yes, that by traversing that, you would be essentially folding
space. Because you would be traveling a huge amount of distance without
actually moving the spacecraft.
However, I do believe that this is more intended as a metaphor than any actual
astrophysical prediction. And so, for very good reason, science fiction
franchises, they have taken advantage of this theory, this unproven, ambiguous
idea, in physics, and used it as an explanation for FTL, much like the warp
drive.
There is no definitive way in which anything in our universe could travel faster
than the speed of light because it would violate causality, it would violate
general relativity. We know for a fact, thanks to Einstein and the way general
relativity has been tested nine ways from Sunday, that matter cannot exceed the
speed [00:10:00] of light, or even achieve it.
And black holes are a perfect visual reminder of that. As we covered in a
previous episode, a black hole is essentially a collapsed star where the force of
gravity on its surface, after it's collapsed to a certain radius, becomes equal to
the speed of light. And consistent with Einstein's field equations, once the speed
of light is achieved, Then you no longer have time, because time dilates as the
speed of light approaches, and if it were possible for the speed of light to
actually be reached by an object, time would cease entirely.
And so, essentially, a black hole, within its event horizon, is essentially an
object and a moment frozen in time. The gravity is so powerful, nothing can
survive contact with it, and any information that falls into it. This includes all
material that is secreted onto a black hole surface. It [00:11:00] will be broken
down right to the quantum level, and that information will be preserved for
eternity.
At least, that was the theory until Hawking revealed that black holes emit
radiation, a. k. a. Hawking radiation. And so that maybe, over time, they will
lose that information. But it would take longer than the universe has existed or
likely will ever exist. A ghost subject, and one for another time. So, in the
meantime, what does the science say about wormholes?
Where does this theory come from? And, as always, that requires a little bit of a
trip down memory lane, a little bit of, uh, perusing the annals of history, and a
lot of big names come up. For example, the first recorded mention of thewormhole as a concept occurred in 1928, when German mathematician and
theoretical physicist Hermann Weyl proposed a hypothesis related to relativity,
electromagnetic fields, and matter, and the.
[00:12:00] interconnected nature of it all, in which he proposed the existence of
one dimensional tubes. And his work went on to inspire American theoretical
physicist John Archibald Wheeler, who coined the term in a 1957 paper that he
co wrote with an American physicist named Charles William Meissner, who is
one of the authors on the seminal book, Gravitation, and whose work also
provided an early foundation for studies for quantum gravity and numerical
relativity.
In any case, they made what is believed to be the first recorded mention of the
word wormhole, and this was in a paper titled Classical Physics as Geometry, in
which they were attempting to describe unified field theories that accounted for
gravitation, electromagnetism, and all other known forces. In the course of this
paper, they said, This analysis forces one to consider situations where there is a
net flux of lines of force through [00:13:00] what topologists would call a
handle of the multiply connected space, and what physicists might perhaps be
excused for more vividly terming a wormhole.
Now, what they were referring to were predictions and the many attempts at
resolving the field equations of Einstein, which included the efforts of Karl
Schwarzschild, the man for whom the Schwarzschild metric is named, and the
Schwarzschild radius. And it was Schwarzschild's work, as we covered in a
previous episode, that predicted the existence of black holes.
However, his work also predicted the possibility of traversable wormholes. And
Schwarzschild describes these wormholes as an eternal black hole which could
be traversable from one point to the other, but only if it could remain stable.
According to Schwarzschild's calculations, these wormholes would collapse too
quickly unless there were exotic matter [00:14:00] with a negative energy
density present in the universe that could be used to stabilize them.
And meanwhile, Einstein and Nathan Rosen, they came together to collaborate
on a paper titled The Particle Problem in the General Theory of Relativity,
released in 1935. And this paper was one of Einstein's attempts to disprove the
concept of quantum entanglements, which he described as spooky action at a
distance.
In other words, a concept he did not care for. Using Schwarzschild's theory on
black holes, he and Rosen described a bridge between two patches of spacewhere one end of the bridge was positively charged and the other one was
negatively charged. And this, they believed, would allow pairs of particles and
antiparticles to become entangled without violating the laws of relativity, and
these became known as Einstein Rosen, or ER, bridges.
A consequence of this theory, though, is that if particles are going to fall
[00:15:00] beneath the event horizon of a black hole and then traverse to
another point in space and time along an ER bridge, there has to be a
corresponding white hole in which the particles are then released. And another
very interesting suggestion to come from this theory was that, in fact, ER
bridges may not be connecting black holes from two points in space time in the
same universe, but in different universes.
Which means, in theory, particles could be exchanged between universes all the
time. However, a paper published in 1962, authored by Archibald Wheeler and
Robert W. Fuller, they argued that a wormhole that connects two parts of the
same universe would pinch off too quickly. And that anything traveling slower
than the speed of light would not be able to make it through.
Nonetheless, many physicists continue to maintain that wormholes could, in
[00:16:00] theory, exist. This includes Stephen Hawking and Kip Thorne. Now,
Stephen Hawking needs no introduction. But his extensive work with black
holes and his expertise means that he is more than familiar with the concept of
Einstein's Rosen bridges, and he believed that it would be possible to stabilize a
traversable wormhole.
Kit Thorne, a noted astrophysicist and the consulting scientist for the movie
Interstellar, he too has argued that not only could naturally occurring wormholes
be stabilized, but he even argued that it might be possible to create one. And
fans of the film Interstellar will no doubt remember that not only did it contain
the first truly realistic representation, visual representation, of what a black hole
would look like, which all came down to computations performed by Kip
Thorne and his colleagues, but a key [00:17:00] element in the story was the
existence of a wormhole that allowed the crew to reach a distant star system.
And the existences, wormhole, and how they described it. How they described
the effects that the crew would experience going through it, and what it would
look like. Again, fans will recall it was spherical in shape, which was a
deliberate choice. This all came down to actual theories proposed by Kip
Thorne and his predecessors.In any case, it was in 1988 that Kip Thorne and Mike Morris, one of his
graduate students, they independently came upon a theory that had been
previously proposed by Homer Ellis, a professor emeritus at University of
Colorado Boulder. When 1973 published a paper called Ether flow through a
drain hole, a particle model in general relativity.
And as Thorne and Morris similarly argued in their [00:18:00] paper, a traversal
wormhole could be held open by a spherical shell of exotic matter, and this
came to be known as a Morris Thorne wormhole. Now, this term has come up a
few times now, exotic matter. And what it refers to is hypothetical particles and
states of matter that have not yet been discovered.
And this includes a theory proposed by Einstein and Satyendra Nath Bose about
a state of matter that was formed when a gas of bosons are reduced to
temperatures nearing absolute zero. And these came to be known as Bose
Einstein condensates. Bose Einstein condensates. And interestingly enough, in
1995, those Einstein condensates were created in a lab by researchers from the
University of Colorado Boulder.
Another type of exotic matter that has come up was negative mass, and this is a
hypothetical type of exotic [00:19:00] matter. Whose mass is essentially the
opposite of normal matter, so much as antimatter is to normal matter, negative
mass is to regular mass. And this too has been predicted, and physicists have yet
to achieve the creation of particles that have negative mass.
However, experiments are ongoing, and some of the results have been
ambiguous, to say the least. Which, in science, can be interpreted as a good
sign. It's not a negative result, it is an ambiguous result, which means there
could be a pathway to success. You just have to keep trying. In addition to warp
holes, the ability to create negative mass would also enable the creation of the
Alcubierre warp drive.
Because, as Miguel Alcubierre originally predicted in his proposal paper,
Alcubierre. Negative mass and exotic matter would be necessary in order to
[00:20:00] create a worm bubble that would allow a ship to expand spacetime
behind it and contract it in front of it, thereby achieving faster than light travel
without technically moving.
So, exciting stuff, exciting potential. But, as always, this remains in the realm of
theory. So, could natural wormholes exist? In theory, yes. Could they be
traversable? Assuming, of course, you had the means to stabilize them. Intheory, yes. Could they be created? Which is to say, could corridors between
one area of space and another be created through the use of negative mass?
Physicists like Kip Thorne do not rule it out. However, wormholes remain
largely a thought experiment at this time. They exist only in theory because
none have been observed in our universe. [00:21:00] As Thorne himself wrote
in The Science of Interstellar, we see no objects in our universe that could
become wormholes as they age.
Which is a Tangential reference to black holes, because as we know, as stars
age, they eventually exhaust their hydrogen and helium fuel and undergo
gravitational collapse, and if they're massive enough, that collapse will be
significant enough to form a black hole. And according to multiple lines of
research by astrophysicists over the past century, it is possible that black holes
are connected to other universes or other parts of our universe.
And who knows, perhaps someday it will be possible for probes and spacecraft
to investigate black holes more closely. To the point that we could actually
confirm various theories [00:22:00] about exotic matter and portals to other
parts of the universe. But of course, this is not a question we can answer right
now.
But it is fun to speculate and it is good to know that there is a theoretical basis
for it. Because, of course, science fiction depends upon these ideas. As any fan
of science fiction knows, the ability to traverse space, going from one star
system to the next, visiting exotic planets, making contact with extraterrestrial
intelligence, all of this is dependent upon the existence of some form of faster
than light travel.
Certainly doesn't apply to all science fiction. In fact, hard science fiction avoids
any FTL concepts or any type of science that is yet to be proven or, based on the
author's own discretion, likely to be proven in the not too distant future. In that
[00:23:00] respect, I would highly recommend an author who we covered in a
previous episode, Alistair Reynolds, himself an astrophysicist.
Most of his works take place in a universe where relativistic space travel is the
only way that humanity is able to go from one star system to the next. And they
do so using powerful drives that are able to generate constant acceleration,
allowing them to get extremely close to the speed of light but never reaching it,
and these are known as lighthugger ships.A very clever term in my humble opinion. Now he too dipped into wormhole
theory on occasion.
And at the risk of editorializing a little, I for one do hope that the Alcubierre
metric and the Alcubierre warp drive and that wormholes are a distinct
possibility that lie in our future, and that if humanity does ever figure out The
secret to [00:24:00] exotic matter and negative mass? That we could enjoy all of
these things.
Especially because if we do find ourselves living in a universe where
traversable wormholes do exist, but the L2BR warp drive doesn't, then creating
stabilized wormholes, that is going to be very, very, very time consuming.
Basically, you have to fly to a distant star system using conventional propulsion,
which at this point I would hope would be very, very exotic and powerful, but it
would still take decades or even centuries to get to some of the nearest stars, at
which point the spacecraft could then go about stabilizing a wormhole, which
would then be traversable and allow for FDL travel.
But you see the point. Establishing these networks would take a very long time.
But what's created [00:25:00] would allow for humanity to not only become
interplanetary or interstellar but potentially intergalactic. Of course, that raises a
whole bunch of other arguments. For example, if all this is possible, then why
hasn't an advanced species done it already?
Why haven't they populated the entire galaxy and are taking a peek at
neighboring galaxies already? Because humanity does appear to be late to the
party in any evaluation of the emergence of life in our universe. That, too, is fun
to contemplate and speculate about. Gets into another favorite topic of mine, the
Fermi Paradox, which I've spoken endlessly about, so I won't do that here.
And, in another break from tradition, I would invite my listeners to comment on
whether or not they think wormholes exist and whether or not we could use
them for the sake of interstellar [00:26:00] travel. Tell us what you think, post it
in the comment section. In the meantime, thank you for listening. I'm Matt
Williams, and this has been Stories from Space.