This video is sponsored by CuriosityStream. Get access to my streaming video service,
Nebula, when you sign up for CuriosityStream using
the link in the description. In the future, there will be no resistance to the widespread
adoption of superconductors. So today is our 250th weekly episode and we’ll
be looking at Superconductors, how they work, what they can do for us, and what the impact
of them will be on our civilization. This is a tricky topic because on the one
hand, we already have superconductors and their impact has been rather large already,
but what we usually mean are room-temperature superconductors. Those would open up doors for us to do some
truly impressive mega-engineering among other technological feats, particularly if twinned
together with the invention of a material that acted as a true magnetic shield, which
we’ll discuss later. Let’s talk about the most obvious impact
first though. Right now, we are always short of electricity,
especially from cheap and renewable sources. However, something like half our electric
production simply goes to waste as heat in the electric lines from your local power plant
to the power outlet in your wall. The longer the line, the more is wasted, and
so often even better and more efficient power options can’t be used because the distance
involved makes it less efficient. Solar panels located in the desert with ample
sunlight, but far from human habitation, lose too much power to transmission distances. Solar is also off half the day at night time
and weak when it's cloudy, but the Earth generally has a steady supply somewhere. If distance wasn’t an issue, we could easily
supply everyone all day from solar because it’s a bright sunny day somewhere. Why is this? Well, most folks are familiar with the idea
of electrical conductivity and resistance, that any given electric wire – or any other
substance – has a certain resistance that any electricity passing through it must overcome,
and it acts like friction on a car, the road friction and air drag just slow you down and
leech energy that must be replaced. Wires do this and power leaks out, wasted
as heat. Now metals in general tend to have lower resistance
than many other materials, which is to say that they conduct electricity better and often
have a much lower resistance as temperature drops. We’d hypothesized it might drop to zero
at low enough temperatures, possibly only at absolute zero, but in 1911 Heike Onnes
found that mercury at 4 Kelvin had absolutely zero resistance. Scientists found some more materials that
could also do this, superconduct, but the problem was all of them had to be ultra-cold,
temperatures not found anywhere on this planet outside a laboratory, or indeed anywhere in
this solar system, so its industrial application was pretty limited. Particularly since those temperatures could
only be achieved with Liquid Helium, which is vastly more expensive to make than Liquid
Nitrogen largely in part to Helium’s scarcity here on Earth. While wrapping all our electrical lines in
sheaths of liquid helium would have dealt with wasted electricity, it would also have
required a huge output of power and money to supply all that refrigerant as it warmed. We also had no idea how superconducting was
happening, and we had thought it would need to be near absolute zero. We’ll get to why in a moment, but first
we should note that since a superconducting wire can have an electric current flow through
it without diminishing, and since running current through a coil produces a magnetic
field, a superconductor can produce a constant magnetic field for free - except for the cost
of cooling it and the initial current input. This is why superconductors are often shown
levitating things such as magnets, so long as you keep them cold enough to superconduct,
they will keep levitating. This is still not free energy, as magnetic
fields do not do work, in the physical sense. A charged object in one can change direction
but it retains the same total kinetic energy. It can circle around for instance, same as
a planet orbiting in a gravitational field. So superconductors are not what people call
perpetual motion machines, in that they don’t generate free energy or violate the Laws of
Thermodynamics, though they could allow an object in a vacuum chamber to remain perpetually
in motion. That’s the issue with superconductivity
in the first place. In an ideal metal or crystal, all the atoms
are nicely lined up and so a wave, like that of an electron carrying charge and electric
current, could go through unimpeded, with no resistance. In practice that perfect lattice of atoms
isn’t going to be perfect, some atoms will be out of place or the wrong kind, the metal
not being perfect pure. There are many other factors that can impact
resistance and conductivity, some of which aren’t temperature based. However, to worsen it, our concept of heat,
at the microscopic scale and even smaller, is really random atoms and such bouncing around
and if they are bouncing around randomly they obviously aren’t perfectly aligned. The hotter something is, the more random bouncing
is involved. So the more resistance we had in that lattice. As we cooled it, that went down but even in
a perfect metal or crystal lattice it couldn’t be zero bouncing around – allowing zero
resistance or superconductivity – unless there was no random motion, which is to say,
no heat, or absolute zero. Which even today we still figure is impossible
to actually reach, even if we can come close to it, with laboratories able to take things
to less than a billionth of Kelvin above absolute zero. Of course, back in 1911 when James Dewar and
Onnes were pushing the limits of cold, they weren’t down under a Kelvin yet and as mentioned,
had already found that some materials superconducted above that. And this is where the notion of a Cooper Pair
comes in. Classic cold superconductors are thought to
work because electrons can pair up tightly and at a lower energy level, when normally
two electrons would instead repel each other. This allows easier transit through a material
so all those random motions don’t matter as much. This pairing can only happen at lower temperatures
and still needs that lower level of random bouncing and heat, but allows them to genuinely
superconduct, at exceptionally low temperatures but not at absolute zero. Now two quick notes there. First, a lot of emphasis should be on how
superconductors ‘are thought to work’ because we are still not entirely sure how
they do work, especially the warmer ones. And second, what temperatures mean for superconductors. Classic cold ones are those that operate under
30 Kelvin, or temperatures you would have problems finding naturally even out at Pluto. When we say warm-temperature superconductor,
we are not talking about what you or I would find warm, or even what Antarctica would. We’re talking about warmer than Pluto, and
generally don’t even call it high-temperature superconductivity rather than warm-temperature
till it reaches liquid nitrogen temperatures, which are still colder than any place on Earth. We've been getting warmer as we’ve improved
research, the current record was set about 33 years after we first encountered a warm-temperature
superconductor, in 1986. That was a copper oxide that superconducted
at 35 Kelvin, and this resulted in a big boom in research on the field. When I was in college for Physics in the late
1990s and early 2000s, our department had a few folks specializing in this area and
we had some superconductors on hand that could operate at Liquid Nitrogen Temperatures – handy
as Liquid nitrogen is vastly cheaper than liquid helium to make and use. To this day though, we still have only theory
for how they function, as it is quite different than the classic cold superconductors. Still even liquid nitrogen is hardly free
nor do great big cooling apparatuses make for cheap electric grids or superconducting
micro-circuits for commercial application. And by the way, finding superconductors that
you can cool with liquid nitrogen instead of liquid helium is pretty important for applications,
especially larger-scale ones. As a rule of thumb, wherever you live in the
developed world, and in whichever decade of the 20th or 21st century, liquid helium costs
about as much per liter as good scotch, while liquid nitrogen costs about as much as milk. And then there’s the fact that Earth’s
atmosphere is 78% nitrogen, so if you compress and refrigerate it yourself, you can pretty
much have all you want and don’t have to truck it in, because it’s all around you. Our high temperature superconductor record
was broken again in 2019 as scientists found one that operated at the scorching hot temperature
of 250 Kelvin… which is -23 Celsius or -9.4 Fahrenheit, so still cold, but that is a temperature
that actually occurs on Earth. Moreover, many of the other ‘warm-temperature’
superconductors, while being quite cold by our standards, would operate on other worlds,
like Pluto, and naturally occurring ones potentially forming something akin to a computer is one
of the more interesting scenarios we contemplated in our look at Non-Carbon Based Life earlier
this year. While our best is still arctic temperatures,
there does seem ever more reason to believe we will find one that can operate at Room-Temperature,
that is the biggest game changer if we can get it. However, a few caveats there. First, we’d probably want a bit better than
room-temperature, though it isn’t entirely necessary, but you wouldn’t want anything
in regular use that stopped doing its job the instant it got a bit warm. Second, they also stop doing their job if
they get impinged on by magnetic fields, either powerful enough ones or sometimes any at all,
depending on the material. We really don’t have good magnetic shielding. Normally we shield from magnetic fields by
sheer distance, or by using materials with high magnetic permeability. The best magnetic shielding generally being
provided by what we call mu-metal, mu being the symbol for magnetic permeability in equations,
and this is an ferromagnetic alloy of nickel and iron, though it’s something of a blanket
term for such materials and we’ve discovered many more that do the job better in one or
more respects. They may be good enough to shield thin wires
of superconductors so that we could use them in small and cheap applications, but it would
depend on how sensitive to magnetic fields a room-temperature superconductor was. We don’t even know if one exists yet, let
alone how sensitive it or any others we might find would be. So, these are less than perfect as shields
but might be enough and would be for certain applications at least. However, as we discussed in our episode Advanced
Metamaterials we do have reason to think we might be able to make metamaterials that shield
far better or perhaps even perfectly. We don’t know if we can make these or how
big, bulky, expensive, or durable they might be. And lastly of course for the hypothetical
room-temperature superconductor its properties in terms of cost and durability would matter
too. If the stuff is brittle and breaks easily
– and many are ceramics - or requires something scarce like platinum or some rare isotope
or Transuranic element, it might be less than useful for commercial or big-scale application. If it is sturdy and cheap but made of toxic
materials, you don’t want it in household items… amusingly mercury and lead were our
first superconductors. All right, let’s assume we had such a material
though, one that worked at room temperature and even a bit higher, and which was decently
durable and could handle magnetic fields well, either from being robust to them or by having
a good shielding material for them, and which didn’t cost a fortune to manufacture or
cause huge health or environmental risks. The first big impact would be on the electric
grid, because you’d have almost twice as much electricity for the same fuel and operation
costs, just from the lack of heat losses from resistance. And you could put your power generators far
away, so building your nuclear fission plants in some very remote place far from people
or seismic activity and in large efficient clusters would be possible. As would transcontinental power lines so surplus
power – say summer daytime solar in Australia or the Sahara could pump to Alaska or Siberia
in the dead of night. No need for batteries. However, superconductors permit some exceptionally
good batteries. Superconducting Magnetic Energy storage, or
SMES, is where you put electricity directly into a superconductor. This is already in use in many applications
despite the coolant cost as it has virtually no delay in charge or discharge. That makes it great for adding to power grids
that can have sudden drops in transmission or spikes in demand, as it can cycle up near-instantly
to stabilize the supply. A room temperature version might allow a very
compact battery that could rapidly be charged, which is obviously ideal for everything from
phones and laptops to electric vehicles. The rapid discharge also opens the door to
things like laser rifles or man-portable rail guns, especially as for the latter the superconductors
would be rather handy for the magnetic coils in that railgun. They’d also be handy for large scale railguns
like the mass driver for launching things into orbit. Lastly, as it is a superconductor, you are
not losing energy appreciably while it is stored, hypothetically, no longer how long
you’re storing it. So one benefit we mentioned, being able to
move power from surplus to places that need it, based on time of day, season, or weather,
is amusingly a bit less valuable as this same technology allows better battery storage too. Though of course even if we don’t have to
cool it we still need to maintain a given battery and build it in the first place too,
so there is still an energy storage cost, just far less. That is not the only power storage method
magnetics allows either. We’ve worked on creating magnetically suspended
flywheels in vacuums. Essentially a disk which you spin using energy
and stores that energy, like any flywheel energy storage or FES System, but which isn’t
losing energy to air drag or friction on its axis. We can already do this, but it is a bit bulky
and not something you’d put in a typical personal vehicle. That is potentially very handy for spacecraft
using electric engines, especially if in coordination with beamed power transmission, since if it
lost the beam for a bit it could keep operating until connection was re-established. Room temperature application is ideal, but
since we’re discussing spacecraft it is again worth remembering that many places are
much colder than Earth, and the vacuum of space – while usually about the same temperature
as any planet or object nearby it would be – can be made very cold simply by use of
shades and mirrors to keep sunlight off it. One problem with putting major bases on the
Moon is the concern about what to use for power, as while it is great for solar during
the daytime, getting as much light as Earth – and indeed more since it has no atmosphere
blocking light let alone clouds – those day times last a couple weeks… but so do
the night times. SMES or advanced FES energy storage gets around
this issue, assuming you can mass produce them, and we’ve got some very cold places
on the Moon down in deep craters where we might house such batteries made of more modest-temperature
superconductors. Cold places in vacuum are not in a shortage
in this solar system, nor are places far from any major interfering magnetic field, so superconductors
may see major use in space colonization even without room-temperature ones. Possibly nearer at home too. We’ve discussed many active-support structures
like the Lofstrom Loop or Orbital Ring, and while both can work without superconductors,
they become much less major power gluttons with them. Since they are in pretty active use as transport
systems, you benefit a lot from having advanced magnetic shielding in play, but if you had
that, then this becomes a truly huge boon to space colonization from the sheer launch
cost savings involved, which are far higher if you’re not having to burn a lot of energy
or coolant on keeping your magnetic launch or support system running. See our episodes on that topic for more information
on why these are awesome for mass transit to space. How about back down on Earth? Well, for mass transit, big levitating trains
sure are nice, but if you’ve got really good batteries and really low-loss power transmission
you can just keep using personal vehicles. Possibly levitating ones too. Potentially even levitating buildings or cities,
though you definitely want to be having good magnetic shielding before you try that. You can also use it as an effective frictionless
surface for the space between a rotating habitat and it’s non-rotating superstructure, which
is particularly handy if you’re trying to employ the trick for getting around tensile
strength limits we discussed in our episode Continent-Sized Rotating Space Habitats. However, the really cool part about Superconductors,
to me at least, is the options it opens up for mega-engineering projects. We often talk about building structures using
active support, such as that orbital ring or what we call an Atlas Pillar, essentially
a long straightened loop of material flowing up then around and down again, over and over,
inside magnets. We looked at this in more detail in Space
Towers, and if there is no energy loss at all, if it is essentially a closed and charged
up loop inside magnetic shielding to form a structural member, then you’ve got something
with an arbitrarily high compressive strength to be building out of. This could allow buildings thousands of kilometers
tall instead of thousands of meters. Combined with its more circular or elliptical
sibling, the Orbital Ring, we could potentially manufacture cheap, durable megastructures
far too large to make from classic materials or even many of the supermaterials like Graphene. Indeed you could fabricate entire artificial
planets this way, or even giant ones, like we looked at in Mega-Earths or Matrioshka
Worlds. So, when it comes to the Impact of Superconductors
on our world, it’s a pretty big one, including potentially letting us build new worlds. We’ve got a couple of announcements before
we get to the schedule including celebrating our 250th episode. First off, for those of you who have subscribed
to our new streaming service Nebula, you already know that we put all our weekly episodes up
there too, not just our early-releases and nebula-exclusive episodes like the Coexistence
with Aliens series. However, I’ve decided to start putting ad
and sponsor free versions of the new regular weekly episodes up there and since those usually
are ready a bit earlier, I will start releasing the weekly episodes on Nebula - ad free - a
day or two before our normal Thursday morning airing. Nebula is an experiment I and a bunch of other
channels started up last year as an alternative to youtube dependence and this is a pair of
features that we all thought our audiences would appreciate, so again the new episodes
of our show will be available there now a day or two early and without ads in them. We’ll continue to experiment and to add
features as time goes on, both there and on Youtube and our other platforms too. Now Nebula is it’s own separate streaming
service but our friends at Curiositystream do offer it as a free add-on if you subscribe
to them, and since they have so much excellent educational content of their own and are running
26% discount if you use the link in the description, it’s a great deal. It means you get a year of both Curiositystream
and Nebula for less than $15, and it helps support this show and a lot of other educational
content which is what Curiositystream and Nebula are all about, and again you can get
a year of both for less than $15 by using the link in the episode’s description. So today marks our 250th weekly episode, which
is a bit of a misnomer since there’s well over 300 videos on the channel between bonus
episodes and livestreams, and these days the episode numbering is essentially what production
week we are in. Amusingly that should also be over 300 as
its been 306 weeks since the original episode on megastructures, just under 6 years ago,
but we didn’t do regularly weekly episodes till early 2016 and amusingly, for fans of
“Arthursdays” I was actually releasing them on Fridays for a while. And these days we do more like 76 episodes
a year, our regular 52 weekly episodes plus a monthly bonus episode plus a monthly livestream. No matter how you count it, it’s a lot of
episodes, and it seems like forever since we began. I’m not sure if anyone who subscribed to
the show back when it only had 1 episode on it in 2014 is still around watching these
days, or how many of you have actually watched every single episode since that would take
nearly a week without pausing for a drink and a snack let alone sleep, but if you have,
thank you, I hope it has been as fun and interesting a journey for you as it has been for me, and
I hope you enjoy the next 250 episodes just as much. Speaking of upcoming episodes, today we were
talking about how superconductors might make it easier to build titanic megastructures,
and next week we’ll take a look not at various types of Megastructures but rather how you
might go about navigating around them and to them. Then on Sunday, August 16th, we’ll be teaming
up the Exoplanets channel and Parallax Nick for a three-part bonus episode, Talkative
Aliens and Laser SETI. The week after that we’ll return to the
Fermi Paradox series to contemplate Galactic Disasters. If you want alerts when those and other episodes
come out, make sure to subscribe to the channel, and if you’d like to help support future
episodes, you can donate to us on Patreon, or our website, IsaacArthur.net, which are
linked in the episode description below, along with all of our various social media forums
where you can get updates and chat with others about the concepts in the episodes and many
other futuristic ideas. Until next time, thanks for watching,
and have a great week!
