This episode is sponsored by Curiosity Stream Gravity is the weakest of the fundamental
forces in nature, but when it comes to climbing up to humanity’s future,
it really draws us down.
A few weeks back we did an episode on Clarketech, hypothetical technologies so advanced they
are indistinguishable from magic.
There we defined it as technologies that either at least had a basis in some plausible scientific
theory, or were very conceptually straightforward, like time travel, faster than light communication,
or anti-gravity.
That was a survey episode covering many of these technologies quickly and we did a poll
on the SFIA community tab to see which one we’d look at in detail first, and anti-gravity
won hands down.
Fortunately it’s a technology that requires very little introduction, as both anti-gravity
and artificial gravity are staples of science fiction, and today we’ll look at both some
of the science that might allow either version, or a close approximation of them, as well
as some less obvious but powerful applications of gravity control like blowing up planets.
Gravity manipulation is an interesting one from a scientific perspective because while
we really have little on the table to allow it, it’s also a very poorly understood force,
which is ironic since it’s the first of the four fundamental forces in nature we humans
learned about, even before Isaac Newton and his fabled apple falling on the head experience.
Any projectile weapon, from a spear, to an arrow, to a rock, experiences the effects
of gravity, and we’ve been compensating for those effects since well before we were
hunting mammoths.
These fundamental forces are quite different from each other: the Strong Nuclear Force
that binds quarks and nuclei together is over a hundred times more powerful than the Electromagnetic
Force that binds electrons to their atoms and atoms to other atoms, and a million times
stronger than the Weak Nuclear Force, which is involved in radioactive decay… but Gravity
is more than a trillion trillion times weaker than even the Weak Force, and unlike them,
it only has an attractive component.
The notion that gravity might have a repulsive counterpart, anti-gravity, is hardly a new
one, and it’s been popular to look at the expansion of the Universe, which results from
the decidedly mysterious Dark Energy, and ask if maybe that’s it.
Fundamentally, gravity is weird stuff, arguably a fictional force under Einstein’s General
Relativity, and elusive at the subatomic level, when we try to merge it with Quantum Mechanics
to obtain a proper theory of Quantum Gravity.
As-is, we can manipulate or simulate gravity a little bit, as we regularly talk about rotating
habitats that achieve it by centrifugal force or spin-gravity, and we can do it by constant
linear acceleration too, since under General Relativity, gravity is indistinguishable from
acceleration.
This includes the reduction of gravity as well, as you could place a spinning ring around
a high-gravity world and feel lighter on it, for instance.
This is very real too, not a partial imitation like magnetic levitation or boots.
Folks often wonder if spinning is really the same as gravity and forget that all those
weightless astronauts in space are only a few hundred kilometers up.
At that distance gravity has barely diminished, instead the astronauts are orbiting, spinning
around the planet, and it fundamentally is the same principle.
Of course practical anti-gravity or artificial gravity would often be enough too, so something
like a compression suit with magnets might allow folks to walk around a spaceship without
experiencing as many of the issues with day to day tasks or their health.
Some folks have theorized it could be possible to convert the electromagnetic force into
the gravitational force, but reports of anti-gravity in superconducting experiments have regrettably
turned out negative.
We also have some tricks we can do with super-condensed matter, such as micro-black holes, or possibly
dark matter if we learned how to manipulate and gather it up, to create high gravity without
needing to pile regular mass in one place where it will want to interact with things.
We can also potentially lower gravity in a similar way, by placing a big chunk of matter
above some high gravity spot to lower it.
There’s definitely a window for a better understanding of gravity that might allow
us to generate it artificially or find some repulsive version of it, and perhaps Dark
Energy will offer that to us if we understand it better.
This has some very powerful implications too.
In fiction this technology tends to be used for letting the crew walk around a ship rather
than floating or levitating heavy loads, or let people fly, or some focused beam or “gravity
laser” equivalent which is often what is said to make tractor beams work in sci-fi.
All would be very useful of course, especially the latter.
I’m not sure what we’d call a gravity laser, a ‘graser’ is normally a gamma-ray
laser, but I think some authors have also used it for a gravity laser.
Regardless of its name, such a device would be super-handy.
A big repulsor beam is a nice defense against both high-speed space debris and actual attacks,
and is at least one way to make a forcefield.
As we discussed in the episode “Force Fields”, even if you didn’t do a classic sci-fi shield,
you could be using such a beam and a good detection system to selectively target incoming
objects or even just swing around a conventional shield, that is, a big, thick slab of mass.
So it would be handy for ships moving very quickly through space, but it’s also handy
for pushing them up to speed too.
We’ve regularly contemplated using stellasers to push against reflective sails of ships
to accelerate or slow them, and indeed this is a type of repulsor beam, though not a tractor
beam you can pull stuff toward you with.
A gravity laser would be nice for that since it would let you slow ships moving away from
you, not just ones moving toward you, or pushing them away faster.
You could also use it to push debris out of the way of your interstellar vessels too.
Also remember, since we’re accelerating or decelerating ships, that gravity and acceleration
are effectively the same.
If you can make a nice uniform field of artificial gravity, ships and their crews, can be surrounded
by this and allow much higher acceleration rates than a crew standing on a ship under
thrust normally could.
Without artificial gravity, they’d be pancaked and smeared against the bulkheads if the acceleration
was too high, as not everything is accelerating at exactly the same rate.
In science fiction, these are often referred to as inertial dampeners, but they’re only
another application of anti-gravity technology.
While we’re speaking of very strong gravitic fields, we should note that the ability to
produce them where you want opens up some big options too.
A star undergoes fusion because the sheer amount of mass and gravity can smash atoms
together, if you can ratchet up gravity you might be able to do the same in a controlled
reactor.
Gravity has interesting and potentially useful effects on light and time.
You could use gravity or anti-gravity to bend light away from you.
Imagine an anti-gravity defence that red-shifts dangerous high-frequency lasers like grasers
to make them weaker when they hit you.
This is also a potentially awesome way to make gigantic telescopes by gravitational
lensing, something black holes or very massive but diffuse objects like galaxies cause.
We could also use it to slow down time, and if you can generate a powerful artificial
gravity field, you could slow time down in a spot, and if you could do it as a uniform
field, you could also do it without shredding people.
We’ll get to the reverse case in a moment, but as you can see, while being able to carry
heavy loads around on a suspensor platform is neat, being able to use that same technology
to put those objects in slow time stasis would seem even neater.
There’d be no more need to preserve food or use fridges as if time is slowed way down
in a localised area, like a food box, anything in it wouldn’t spoil.
It’s also a great way to put crew into stasis for a long journey or have time for them slow
down so they experience time between stars as days rather than centuries, one of the
methods we discussed in the “Sleeper Ships” episode.
Needless to say, you can also use this tech to let you build super-tall buildings or terraform
tiny moons or asteroids to be Earth-like, rather than having to spin them or drop a
micro-black hole into them for your gravity.
You could also potentially be using this as a way to deal with dangerously old and massive
stars, perhaps wrapping them in solar collectors to power your anti-gravity machine to decrease
fusion in their cores and remove matter.
Of course, awesome tools also make awesome weapons: you might be able to adapt it into
method of detonating stars by ramping up their gravity, or crumpling a spaceship or even
a planet like an empty beer can.
You could even detonate a planet by simply removing it’s gravity so it blew apart under
all its stored heat energy.
Scaled up large enough, you might be even be able to use it to fight the expansion of
the Universe, dragging galaxies back toward you that dark energy is pushing away.
We also can’t rule out, even though it would be at odds with our current, admittedly limited,
understanding of gravity, that you might be able to make a material that just blocked
gravity, akin to the anti-gravity paint, Cavorite, in H.G. Well’s “The First Men in the Moon”.
At the very least, if one can produce anti-gravity, or just artificial gravity, you could effectively
nullify external gravity, but it would be neat to have some material that did it, like
Cavorite.
Suddenly you can make big floating cities without needing to rely on buoyancy, active
support, or any of the other methods we looked at in Cloud Cities.
Construction becomes a lot easier and simpler too.
It also means you can build impossibly big.
Often our limitation in discussing truly enormous megastructures is how we could possibly make
something able to handle all the weight involved, but sometimes, for the very biggest, we have
to worry they’d be a black hole even if they didn’t collapse, simply by their sheer
overall mass, like the biggest type of Mega Earth Birch Planets, which are so huge that
their lower levels actually have time run slower on them than their higher ones.
If you can manipulate gravity, you can potentially remove even that barrier.
You can also build some rather bizarre worlds, like a pair of double planets that just hung
next to each other with a land bridge you could walk between, or stabilize formations
like a Kemplerer Rosette or other weird orbits.
Ultimately, this technology offers one more really awesome advantage.
If you can produce anti-gravity, you might be able to look inside a black hole, and indeed
most wormhole or warp drive models rely on some type of negative matter to function,
which this could replace.
But that’s not the only way it would potentially allow faster than light travel.
I suggested using it to slow time immensely, for stasis, but that’s normal artificial
gravity.
With anti-gravity you could potentially do the reverse, speed time up.
That’s very handy for throttling things like constant-rate passive decay nuclear reactors,
or to give you time to rapidly react to a crisis.
But it also allows you to start bending space and time, maybe reversing them or even entropy,
not just contracting as normal gravity does, and that opens the door to both faster than
light travel and time travel, both of which are Clarketechs themselves that we’ll look
at down the road.
I’d be remiss if I didn’t mention that one of the more popular theories to explain
gravity’s massive weakness compared to the other forces, the Hierarchy Problem, is that
it might be spilling over to other dimensions or parallel realities, in which case it might
let us travel to some very interesting places too.
As you can see, anti-gravity and gravity manipulation in general, would let us do a lot more than
just fly around or carry heavy objects.
It would be a complete technological game-changer for our species if we ever discover and develop
it.
As to whether or not this will always be relegated to the realm of science fiction, or a Clarketech
we might one day have, that’s impossible to say yet, but as we said at the beginning,
gravity is something we still know so little about, and that has the silver lining of leaving
a lot of doors open that might lead us to some interesting places… or interesting
times.
Gravity remains an elusive force, not fully understood for all that it’s the first one
we discovered and studied.
As we saw today, a greater understanding of it may unlock marvels in the future, but what
we already know about it has be instrumental to many of our great triumphs of science and
engineering, including the Moon Landings, which we celebrate the 50th Anniversary of
this year.
Gravity is an a fascinating and amazing thing, and if you’d like to learn more about, trying
out the documentary Amazing Gravity on CuriosityStream, which discusses it and our current experiments,
like the LIGO gravity wave detector.
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We have a number of fun episodes coming up on the channel this month, starting this Thursday
when we’ll celebrate International Pet Day by taking a look at what the future may have
in store for our furry friends.
And the week after that, by popular request, we’ll take a look at the concept of giant
war robots, and ask if such machines might have a future outside science fiction.
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Until next time, thanks for watching, and we’ll see you Thursday!