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. Dark Matter is the most mysterious substance
in the Universe, and also what most of it seems to be made of, and yet it may be the
keystone of building future civilizations. Dark Matter⌠we donât even know what the
heck the stuff is, so it might seem hard to discuss technologies that make use of it.
At the same time, we do know a few things about it with great certainty, and a few more
with some confidence, and one of those is that Dark Matter makes up the vast majority
of everything in this Universe. Given that it does make up most of everything, finding
ways to use it is likely to be on every civilizationâs wish list of technological advancements, and
thatâs our main focus for today, how civilizations would use this hyper abundant material if
they could, and in what ways they might. For a type of matter that is apparently so
common, it is rather irritating that we know so little about it, and we should probably
start by talking about what we do know about it.
First, it almost certainly exists. That irritates a lot of folks and often raises many objections,
some are reasonable objections, but some of those arenât terribly valid. As an example,
weâve never seen any dark matter directly, and that seems a good objection, until one
remembers that weâve never seen most of Earth directly, including its mantle and core,
and never hesitate to discuss its interior, nor the interior of our sun or any other star.
We also donât âSeeâ subatomic particles, theyâre smaller than light waves and we
detect them mostly by blowing stuff up and looking at the pattern of the wreckage to
see what could have caused it, so to speak. So there are a lot of legitimate objections
to dark matter and weâll discuss some of them, and discussed more of them a few years
back in our Dark Matter episode, but the ones hinging on us not being able to directly detect
it arenât good ones. Most particles we first detected were detected by indirect means,
like picking up gamma rays to prove the mass of the electron and positron, after a pair
of them had collided and emitted those gamma rays. Generally weâve measured the mass
of other atoms and their interiors by seeing how much other charged particles were deflected
by the protons in their core when passing by them.
Nor is the time argument a good one. Folks say weâve been looking for it for a couple
decades now and still havenât found it, but thatâs not true. We havenât been looking
for dark matter unsuccessfully for a couple decades, weâve been looking for dark matter
unsuccessfully for over a century. We have all sorts of particles we hypothesized
decades before we proved they existed⌠and considerably more we hypothesized and havenât
found yet or even ruled out. Dark Matter has been bugging us a lot longer, since before
we even knew what a galaxy was, what subatomic particles were, what 2 of the 4 fundamental
physical forces were, or how those particles interacted with those forces or didnât.
Way back in 1884 Lord Kelvin estimated that there had to be a lot more mass we couldnât
see than we could see to explain the velocities of stars orbiting the milky way. He didnât
assume any type of exotic matter at the time, just mundane matter not in stars, and that
was the general notion for a long time. We just assumed it was various things which were
normal but dark, like interstellar dust or planets, or later even stellar remnants. Indeed
that was one suspected culprit back in Kelvinâs day because we assumed stars gave light off
from being formed very hot and slowly cooling, as we had no clue that nuclear fusion took
place inside stars. Problem was, we did find a lot of this mundane dark matter, and it
never even came close to adding up. In modern times, we know that virtually every
galaxy we can see has a lot more mass than the stars we see in it can account for. But
how do we know that? The calculation uses the fact that for an object in a roughly circular
orbit, the centrifugal force on it is equal to the gravitational force itâs subjected
to by the body it's orbiting. So if we determine the distance to the galaxy of interest, we
can use itâs angular size in our field of view to determine its radius. If we observe
it over time, we can measure the speed of the objects orbiting at the galaxyâs edges.
From the orbital radius and velocity, we calculate the centrifugal force, which is equal to the
gravity exerted on it, which tells us the mass of the galaxy. But when we use the starlight
from a galaxy to determine the numbers and types of the stars in it and add up the masses
of those types, we consistently find that the luminous mass of most galaxies is only
about 1/10 of their gravitational mass. We can see the speeds of stars on the outer
edges orbiting them and we can see how much they pull on neighboring galaxies, and every
alternative answer for it not being gravity didnât work out. Tons were tried.
Well then we had to ask ourselves what generates gravity. In point of fact it isn't actually
mass, any type of energy generates gravity, but mass is one type of energy, under Einsteinâs
E=mc², and all the other types of energy except light speed objects like photons are
associated with mass. For instance you can have an awfully lot of kinetic energy on an
object with mass, but for it to come anywhere near paralleling the amount of energy tied
up in the mass itself, it needs to be moving at relativistic speeds. Galaxies are hugely
massive affairs but even they canât contain objects moving at those speeds for long, so
your only two remaining options are rotational energy of certain very dense objects, like
black holes, neutron stars, and white dwarfs, or the random kinetic energy of particles
in very hot objects, again like neutrons stars and black holes. Only a tiny fraction of stars
end up as neutron stars and black holes, and all known stars combined wonât add up to
the missing mass, so it's not these stellar remnants, there just arenât enough of them.
But it also means that missing energy generating all that gravity in galaxies has to be mass
energy. Probably, we canât rule out some other type
of energy storage besides the known 5, which are mass, kinetic, potential, thermal, and
radiant energy. Dark Energy does not fit the bill incidentally, that appears to be evenly
spread throughout the Universe whereas this missing mass we call dark matter clumps in
galaxies. This is also why we often say it has to be cold, which in physics terms and
context means the individual particles or objects of dark matter canât be moving very
fast or they would exceed a galaxyâs escape velocity and not clump into galaxies, this
overall motion is random and thus can be thought of as heat energy or temperature.
Galaxies tend to have escape velocities on the order of of hundreds of kilometers per
second, so âColdâ is a rather dubious term here, something with the velocity sufficient
to escape a galaxy and the mass of a proton or neutron still has a temperature comparable
to the inside of a star, in the sense of random kinetic energy being heat energy. Thatâs
nothing compared to relativistic hot temperatures though, and is a bit problematic considering
we always assume everything in the early Universe was ultra hot and cooled down by radiation
and collision. Dark Matter doesnât emit photons as heat radiation, and do not collide
with anything, even other bits of dark matter, or do so very infrequently.
Which is the other thing, what is a collision? Down at the atomic scale the whole concept
of physically rigid objects is out of play, it just doesnât mean anything. Collisions
occur using those fundamental physical forces. Not every known particle interacts with all
of those either. Electrons, and their big brothers the muon and Tau particles, along
with their anti-particles, are what we call leptons, and they donât even notice the
strong nuclear force that binds quarks together to make things like protons and neutrons.
We have 4 fundamental forces, quarks, and thus things made from them, interact with
all of 4, though many of those constructs, like the electrically neutral neutron donât
interact much with one of those. In the same way, neutrinos donât interact with the strong
nuclear or electromagnetic force, just gravity, which everything seems to, and the weak nuclear
force, and the latter so weakly that a neutrino could pass through a light year of lead and
likely make the trip uninterrupted. Our best neutrino detection methods manage to nab the
occasional one interacting with matter, while countless trillions will have passed through
that same spot first. Neutrinos move at near light speed, within
the tiniest fraction of a hairsbreadth of light speed, and have only a smidgen of mass,
less than a millionth of what an electron has or a billionth of what a proton or neutron
has, and a neutrino-antineutrino rest annihilation would produce an infrared photon, not the
millions or billions of times more powerful gamma ray photons those other particle produce
when annihilating with their antimatter opposites. They carry far more energy though, and it's
almost all kinetic energy. Neutrinos are not our focus for today, they
are not dark matter though have been a popular suggestion in the past, but if you could make
a thin foil able to absorb or reflect neutrinos, youâd have a rather awesome solar sail,
and if you could make the equivalent of a Laser, a neutrino beam, that would be a great
way to shove spaceships around, since it would mean a super powerful beam only handy for
ship propulsion, not a giant doomsday beam like laser propulsion platforms would be if
used for militant intent. The most popular suggested particle for dark
matter these days is most easily thought of as something like a heavy neutrino. Neutrinos
move at near light speed because they are created in events that typically kick out
an electron and proton, or their antiparticles, at fairly high speeds, and the neutrino gets
the same kick, but having vastly less mass, exits the event at a vastly higher speed.
Imagine instead that such a particle had the mass of proton or neutron or maybe even more,
we do have some elementary particles more massive than them, 3 of the 6 quark types,
charm, top, and bottom quarks out mass protons and neutrons, the top quark by a factor of
a couple hundred, as does the electronâs big brother the Tau particle, and two of our
4 gauge bosons, the W and Z Bosons â the other two types of gauge bosons are the photon
and the gluon, gauge bosons are what transmit the fundamental forces and the W and Z Boson
being supermassive is why the Weak Force, which they transmit, is so weak, which is
to say, so short range, they decay so rapidly they barely have time to carry the force anywhere.
The Higgs Boson also outmasses protons and neutrons, and by more than a hundredfold.
So of the current 17 elementary particles in the Standard Model, of which neutrinos
are 3 incidentally, 7 of them are more massive than protons and neutrons, which are not elementary
particles, and between the most massive, the top quark, and the least massive, the neutrinos,
there is a mass difference of around a trillion. Keeping all that in mind, the idea that thereâs
a particle as weakly interacting as a neutrino but more massive than a proton or neutron
doesnât seem that far fetched. These Weakly Interacting Massive Particles, called WIMPs,
are probably the most popular category of candidate for dark matter and will be our
primary focus for technologies to discuss today. But they donât have a lock on the
title for dark matter constituents, and not all of them require some new elementary particle.
Many of these donât even require some unknown type or quantity of matter, like MACHOs, or
Massive Compact Halo Objects, such as black holes or brown dwarfs, and we have extensively
discussed how valuable black hole technologies can be in other episodes, though MACHOs are
not viewed as a good dark matter candidate at this time. However mundane solutions other
than new types of particles can still represent valuable knowledge for new technologies. Remember,
one way or another something generates an effect that causes either a great deal more
gravity than all the known mundane matter around, or alters a fundamental force like
gravity or electromagnetism to operate other than inverse square at big enough distances.
If such variations exist, they can probably be exploited for technology, such as reversing
them so gravity was stronger at nearer distances, for instance.
One example is MOND, Modified Newtonian Dynamics, which was suggested in the earlier 1980s as
a dark matter solution by proposing that gravity only acted as an inverse square force â weakening
with the square of distance â out to a certain distance, beyond which it got much weaker.
That doesnât necessarily require magic either, force carrying particles can decay over distances,
thatâs exactly why the weak force is so weak, the W and Z Bosons decay before covering
even atomic distances, let alone astronomical ones, so if the graviton had a half-life of
a billion years, gravity a billion years travel away would be half as strong as suspected.
Thereâs an issue with that, a graviton would have to have some rest mass, particles with
no mass experience no time and thus canât have a half life, and gravity moves at light
speed which no particle with mass can do, but gravity is hard to detect and the neutrino
has a tiny amount of mass and moves within a fraction of light speed, as the theory suggests,
so could a graviton, potentially being less massive and faster than even a neutrino. MOND
had quite a following and had a fair few variations, but fell out of favor with the detection of
the Bullet Cluster in 2006, a pair of colliding clusters of galaxies about 4 billion light
years away. Weâll skip discussing why today, especially as there are some rebuttals in
spite of many folks saying the bullet cluster shot MOND dead. See the episode on Dark Matter
for more of the suggested types too. I mention it because if you found out that
gravitons had a rest mass and could decay, for instance, that might start implying ways
to generate gravitons without lots of mass or reflect or bounce them around, make a gravity
laser, or GRASER, things like that. We are very limited in discussing technologies relying
on matter, or forces, we donât understand, but this is what we can discuss today.
Some are easy, if Dark Matter is any sort of particle that has mass, but doesnât interact
much, then if you can find something it does interact with, you can scoop it up and use
it as a cheap source of mass. It would be useless as a building material, but becomes
great not just for making gravity on artificial planets, freeing up not just valuable heavy
elements but even hydrogen and helium for other uses, it also lets you do strange stuff,
like create a big ball of dark matter with a deep gravity well, and yet so weakly interacting
you could fly right through it. As an example, what happens if you dump around
a stellar mass of dark matter into an existing star? None of that dark matter is getting
blown away by that or sinking into the core, it just floats around generating gravity and
minding its own business. The gravity it creates though would not, and would squeeze that star
down even more, speeding up fusion. It is potentially handy as a fuel source too, dark
matter should have all the energy per unit of mass anything else does, so if you stuff
it down a black hole it would work as a starship fuel, see our black hole starships episode
for discussion of how we can use black holes for ships and power.
So we do have at least one known way to manipulate dark matter. It does react with gravity, and
while it would be very hard to get into a black hole, once over the event horizon it
is as stuck in there as anything else. Itâs hard to get in because black holes are small,
so the only way matter ever ends up in one is if by some freak chance it happens to run
into the event horizon straight on. Normal matter can be sucked into an orbit of a black
hole and as more of it accumulates, the bits orbiting the black hole can start bumping
into each other, getting hot and falling in â this is the accretion disc. Dark Matter
doesnât do that. If it gets into orbit around something, it will just keep orbiting, not
clumping together. This is why dark matter in galaxies forms a roughly spherical shape
while the matter in galaxies tends to form more of a disc.
But dark matter can be absorbed by a black hole. And we estimate thereâs a bit more
than a protonâs mass of dark matter per cubic meter of intra-galactic space. Now a
3-solar mass black hole, which is generally about as small as can naturally form, will
have a cubic volume inside its event horizon of about 3 trillion cubic meters, and would
have absorbed all that dark matter locally present, but thatâs only going to be about
4 picograms of mass, and even the big monster at our core, with a million times more mass
and a billion, billion times more volume, would only have swallowed about 4 tons of
dark matter. Of course the stuff is moving, not static,
so it would be more than that. Letâs assume we shot a black hole with a square kilometer
of cross section through a galaxy on a 100 thousand light year path, or 10^21 meters,
or slicing a column through a galaxy of 10^27 cubic meters. Weâd still have only swept
up a couple kilograms of dark matter. You can throw on more sail, so to speak, by having
a cross section tens of thousands of kilometers across or even larger, one 10,000 kilometers
across will sweep up dozens of trillions of tons of matter. Or deflect it or capture it
for later use if weâre talking about a material that absorbs dark matter instead of a black
hole, or an artificial event horizon. Collecting dark matter is not likely to be an easy task,
but if you can do it, then it represents a vastly bigger supply of matter and energy
than all our mundane sources combined. Itâs also quite possible there are dark
matter only interactions, such as dark matter antimatter annihilation, or dark matter fusion,
that might only be possible when you squeeze the stuff in rather tightly. If you had two
such beams, one dark matter and one anti-dark matter, when and where they collided might
be a very energetic event. That might also be a terrifying weapon since dark matter would
be hard to detect or deflect. And thatâs assuming it doesnât have other strange properties,
many proposed dark matter candidates interact strongly with space, time, other matter, or
other forces. As a reminder certain scenarios for dark matter
would imply the ability to play with gravity more than weâd currently expect, and things
like flat event horizons or gravitational scoops might be on the horizon at that point.
Imagine for the moment we had some bit of Clarketech that let us stretch a black hole
into a disc, like it was some balloon we could squish flatter. Now that implies the ability
to manipulate gravity so it didnât radiate omnidirectionally, but let's say we could,
either flattening the gravity out into a disc or squishing it into a pair of polar jets.
See our anti-gravity episode for more discussion of gravity-based technologies, but such manipulation
might let you have a spaceship that could suck in matter, even dark matter, as it flew
by. Thatâs also a potentially potent weapon and shield too, though it should be noted
that any time two event horizons touch they will merge to an external viewer.
A black hole event horizon has a radius proportional to its mass, and a cross-section proportional
to the square of mass, so you can make really enormous black holes and get dark matter that
way and presumably an awful lot of dark matter will get absorbed in the post-stellar era
of the Universe as you start having all other matter get sucked into black holes all orbiting
each other and perturbing everything else orbiting, including dark matter, till it combines
together or gets ejected into the extra-galactic void.
Of course that scenario would tend to imply you didnât have little bits of physical
dark matter lying around in favor of something like MOND, but it's also possible the solution
to dark matter will turn out to be two different effects. Which is to say we have problems
pinning down what dark matter is because our predictions keep missing, and they might do
so because its two overlapping and unrelated effects that amplify a given net effect weâre
seeing, as in we do have WIMPS and we do have decaying gravity, but fewer and less of them.
You would need to have someway to manipulate the stuff, but if you do it is very useful
â probably with valuable properties we donât even know about, you might be able to make
unique materials out of it, but in space where things are quite empty, it's nice to have
something to push against but only when you want to. Neutrinos and neutrino-like particles,
weakly interacting particles, if you have something that can interact with them more
strongly, it lets you use them â potentially selectively â to interact when you want.
When flying through space I want to interact with nothing, except for when I do, like for
slowing down or turning, so we often contemplate unfurling reflective solar sails or magnetic
fields to interact with solar wind. Ones able to work with neutrinos or neutrinoâlike
types of dark matter would be useful for the same reason. Dark matter is not dense, but
with a big enough sail youâll hit some, and the momentum exchange is going to be based
on your speed. Also if these are particles, it may be possible
to build something out of them if we understand them better, on the flip side, the ability
to mimic this weak interaction or non-interaction can be handy. We often see force fields in
science fiction as a means of defense, but the other popular method tends to be turning
invisible or ethereal, so you either couldnât be seen or things went right through you.
In practice that has to be both, since folks can only see you if light bounces off you,
which means a laser beam would bounce off you too, or more importantly would vaporize
you. If I can see you I can interact with you and if I can interact with you, I can
hurt you, or use you to hurt someone else. But if you can make yourself unable to interact
or be interacted with, thatâs a very good defense, and if you could make your ship or
space station have that weakly interacting property temporarily, or even build out of
dark matter, thatâs a very good method of both stealth and defense.
As an example of weaponizing WIMP-style Dark Matter, you could probably put a cloud of
it around someoneâs planet as a way of keeping them earth-bound, positioning it either to
raise the surface gravity, or to make a cloud in circular orbit over the planet, so the
surface gravity stayed the same but the escape velocity was arbitrarily high. You could wrap
that planet so thick in dark matter that time slowed down on it and only relativistic spaceships
could leave it, a good way to quarantine a worrisome species you didnât want out in
the galaxy but didnât want to interfere with or destroy - a situation reminiscent
of the people of Cricket from Douglas Adamsâ novel Life, the Universe, and Everything.
So weâve talked about spaceships and power, and again itâs a great power source simply
as raw material we can feed into a black hole that is abundant and not useful for other
things, assuming of course we can find a way to gather it. However, same as we discuss
filling shell worlds up with hydrogen or black holes to generate gravity, dark matter offers
that same route. We donât know much about it, but we know it doesnât interact much,
even with itself, so we should be able to cram the stuff together quite tightly without
the normal pressure issues. We normally say if you want gravity on something small, without
using spin-gravity, you need micro-black holes, but ultra-dense dark matter might be an option
too, squeezing tons of it into a volume the size of a pinhead. It's going to act very
differently than normal matter in a lot of counterintuitive ways.
For instance if you had a solid block of the stuff cooled down to ice cube temperatures
and threw it into a pot of boiling water, it would not heat up. Partially because it
would fall right through the pot, but if that pot were lined with whatever your hand was
covered in to toss it in, then the ice cube of dark matter could sit in that boiling water
for eons and pick up no heat from the water. It would also bounce up and down on the bottom
of the pot over and over again, unaffected by the water. Same dark matter could fall
through the pot, and the Earth, and fall through the center and right back up again, then down
again, over and over. If youâve got something you can sheath it in, that it does bounce
off of, then you could be making ultra-dense and heavy objects, which is very handy for
certain more abstract megastructures where you want gravity lower or higher in certain
places. Unsurprisingly its use as a source of cheap
mass appeals to me for worldbuilding, and that might bias me towards the WIMP version
of dark matter, but other versions would have their uses too. Some dark matter options include
particles that interact with gravity and some unknown fifth force, and if that force only
interacts with dark matter we wouldnât even see it, except in its tendency to draw dark
matter together but not very much. This has some problems, for instance it canât be
too strong or, since dark matter does interact with gravity, that fifth-force interaction
should allow more clumping and result in giant black holes all over the place.
We also tend to assume dark matter, if a particle, would have an antiparticle, and when it annihilates
it obviously doesnât produce photons as most commonly happens in matter-antimatter
annihilation, as we would notice that. Unless it does so at the 1.9 millimeter range, that
of Cosmic Microwave Background Radiation, which is unlikely and would really mess with
our current cosmological models. But it might annihilate into some other form of energy
too, for instance dark energy, which causes bits of new space to emerge all over the place.
I often make a point of telling folks that in spite of the similar name, and extreme
abundance, dark matter and dark energy donât have anything to do with each other. That
we know of anyway, and there are a few dark matter theories that do tie it to dark energy,
such as GIMPs, Gravitationally-Interacting Massive Particles, which some folks feel fit
better with the Vacuum Solutions to Einsteinâs equations for gravity, the basic notion being
bits of dark matter were singularities of dark energy.
As I mentioned earlier, its not mass that generates gravity, its energy, and mass is
just the easiest dense form of it, and so you can make a black hole or singularity out
of any very dense clump of energy, cram enough photons in one place fast enough and youâll
get a little black hole. So presumably cram enough dark energy in one place and you get
a singularity too. Though given that dark energyâs only known property is its association
with expanding space Iâd wonder how you would cram it together. But it might be crammed
together initially, and decays, as we expect small black holes to do, and causes space
to emerge when it does. Primordial black holes is another popular
dark matter option. The early universe was super-dense and black hole formation without
a supernova implosion, or even bits of energy that never expanded in the first place, are
certainly plausible options. One issue with that is that we think black holes decay, and
the smaller the faster, thatâs Stephen Hawkingâs original famous contribution to physics. It
is only a theory, there is no experimental proof of black hole evaporation. Assuming
that is right, then a primordial black hole could not mass less than 10^11 kilograms,
100 megatons, or they would have evaporated by now. Now this means none of them could
be, or we would see the radiation of their evaporation all over the place. We donât
know that primordial black hole mass would be evenly distributed, with some massing a
ton, some 100 tons, and some 100 billion, and all points in between, but we do know
it canât be evenly distributed at masses below 100 megatons unless our concept of black
hole evaporation is wrong. Otherwise we would see radiation being emitted corresponding
to those black holes evaporations. There are a number of other issues with primordial
black holes as dark matter and the option, like MOND, is less popular these days, but
if true it would make for a great technology, see our black hole episodes for why. But thereâs
some more problems there too. First, if black holes do not evaporate, then they become eternal
traps for matter, though we can still generate power with them by dumping matter into them,
though it is hard to put matter into a micro-black hole.
However they should be able to absorb matter rapidly inside something like a neutron star,
and were that the case the larger ones, in excess of a trillion tons, would be able to
capture mass in a neutron star and ought to cause detonations of them that weâre not
seeing. Indeed all things included, it's really only black holes in the 10 to 500 gigaton
range that would have a decent chance of not leaving various other telltales of their existence
weâre not detecting, and we donât know any reason why primordial black holes would
have formed in that mass range but not in others. Of course we donât know why all
the various subatomic particles come as specific masses either, like 511 kilo-electronvolts
for the electron, so primordial black holes might do so for the same reason.
Assuming they did though, and were our dark matter candidate, they would potentially be
very handy. The ones on the higher end could be force-fed matter to make them bigger, but
the smaller ones, at 10 gigatons, would give off about 3.6 megawatts of power, and do it
for quadrillions of years, while those on the higher end, 500 gigatons, would give off
1400 watts, and for even longer, nearly a billion-trillion years. Because of their sheer
mass they donât make for good starship drives, but would be created for stationary places
and indeed youâd probably just build around such medium sized primordial black holes as
you found them. We would also hopefully be seeing them in the future by getting better
at detecting the background radiation they would be giving off universe wide and isolating
it from other known sources, like the CMB. Fundamentally though the real power of Dark
Matter probably wonât be for power generation, thatâs just something that seems a probable
use based on what little we know. As a last example, one of the candidates for dark matter
is that it isnât crunched down mass or even energy but crushed down dimensions, and both
additional space dimension and additional time dimensions, and if that were true and
became something we could work with, opens up all sorts of scenarios like storing time,
manipulating time, and maybe even twisting or ripping space-time.
Fundamentally the more we learn about Dark Matter, the more we can explore what we might
do with it, but I hope from today it becomes clear why wanting to find out what dark matterâs
properties are is about more than just answering a big question about what the Universe is
made of, it's about recognizing that anything that abundant is useful simply in its abundance,
and that its sheer mysterious nature implies properties we might be able to use for goals
as mysterious and massive as dark matter is itself. One of the things we were discussing today
was how even though we cannot see Dark Matter directly, we can still know itâs there in
much the same way we know what the inside of atoms or our planet or our Sun looks like.
It reminded me of a topic in a similar vein folks often raise, and thatâs if mathematics
is a real thing or something humanity made up, is math invented or discovered, and my
friend Jade from Up and Atom, who were previously teamed up with to discuss Boltzmann Brains
& Anthropic Principle, recently released a Nebula Original addressing if Math was invented
or discovered. She is one of a number of science and education
creators we teamed up with to form Nebula, our Streamy-Award Nominated streaming service,
a little over a year back and its exploded since its inception, allowing us to invite
in more creators and get a bit more ambitious with original content, like our Coexistence
with Aliens series. Itâs also where you can watch episodes of SFIA a couple days early
and ad free. Now you can subscribe to Nebula by itself
but our friends over at Curiositystream, which is home to thousands of top notch science
and education videos, have teamed up with us to offer Nebulaâs content along with
their own, if you sign up at the link in the episode description. That means you will not
only get Curiosity Stream, and get to see their excellent shows like Space Phenomenaâs
episode on Black Holes, but can also catch SFIA episodes early and without ads, and help
support our show while youâre doing it, as well as see amazing exclusive content from
our sibling shows. Again you can get a year of both Curiositystream
and Nebula for less than $15, get to support the show and see our episodes early, and get
all that for less than $15 by using the link in the episodeâs description.
I also wanted to thank everyone who's been supporting Nebula, and for those watching
the episode there, I was just expounding on some of the improvements weâre making and
planning and how much fun it is to get to interact with so many other creators. Iâve
heard some horror stories of working with various artists or actors over the years,
who were monstrously egotistic or hard to work with, so Iâm always pleasantly surprised
by how fun and down-to-earth just about everyone Iâve met has been, from the smaller shows
all the way up to the giants ten times our own showâs size or more. 2020 was a hard
year for a lot of folks and some creators did end up tossing in the towel, especially
those with newer channels still in growth phase. I know in some cases it was from funding
drops, so while Iâm thanking the folks supporting us on Nebula, let me also thank all our Patreon
subscribers who stuck with us through the crisis, and the recent re-shuffle on that
platform, this channel literally would not exist without you, nor would countless other
shows. So this weekend we have another SFIA Scifi
Sunday episode, where we will be examining the notion of alien cohabitation, and we will
discuss both the structures meant to support multiple alien ecosystems and the relationships
we often see in science fiction, of aliens and humans marrying and having hybrid kids,
on Sunday, February 14th, Valentineâs Day. Then next week weâll be looking at Orbital
Bombardment, as we return to our Space Warfare series, before closing the month out with
an episode on Colonizing Giant Stars in two weeks and our Monthly Livestream Q&A on Sunday,
February 28th. If you want alerts when those and other episodes
come out, make sure to subscribe to the channel, and if youâd 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. You can also follow us iTunes, Soundcloud, or Spotify to get our
audio-only versions of the show. Until next time, thanks for watching, and
have a great week!
So... what exactly does storing time refer to?
One thing I've always wondered when they say a galaxy is moving "too fast" Do they take into account that objects create time dilatation from both mass and speed?
Maybe from the Galaxy's point of view the time dilatation of it's own mass including dead stars and dust is enough to hold it together at it's current speed?
If you take some dark matter and it drop it into a black hole, and out comes Hawking radiation, did you just convert dark matter into regular matter?