[MUSIC PLAYING]
Movies, books, and TV shows
paint fairly gruesome pictures
of a zombie plague.
But they are usually
vague about precisely how
the epidemic begins.
Today, I want to discuss a
potential back story that's
less ridiculous than it sounds.
Could a zombie apocalypse start
with a routine trip to space?
[MUSIC PLAYING]
In some stories,
zombies are slow.
In others, they are fast.
Most fictional zombie universes
share two basic features.
You're going to need a weapon.
And the zombie phenomenon
starts unexpectedly
and spreads quickly, which is
why it wreaks so much havoc.
Now, the underlying
zombification mechanism
varies from store to store.
But often it's envisioned
as an infectious disease--
hence the abrupt onset
and rapid spread.
The disease vision
of zombie apocalypse
has so much in common
with real world epidemics
that the CDC actually developed
a zombie outbreak preparedness
plan.
And the Pentagon had a zombie
outbreak training exercise.
In fact, non-joking
textbooks and academic papers
have been written with detailed
mathematical and computer
models of how a zombie
epidemic would spread.
By the way, for
maximum survival,
you want to go to
Montana or Wyoming.
See the link in the description.
Unlike other
government agencies,
NASA still hasn't gotten
on the zombie train.
But maybe they should
because one scenario that's
more plausible than
you might think
is that a zombie apocalypse
could start in space.
It may not be obvious.
But spaceflight introduces
some unique wrinkles
into how infectious diseases
might originate and spread.
Let's start with bacteria.
In 2006, researchers
sent some salmonella
on the space shuttle, brought
it back down to Earth,
and then infected mice with it.
90% of them died
compared to just 60%
from regular salmonella.
The lethal dose
of salmonella also
dropped to just one-third
its usual level.
More infectious bacteria flown
on subsequent shuttle missions
showed similar changes.
What's weird is that the
salmonella didn't mutate.
Instead, many of its genes
just became over-expressed,
including ones that
make it more virulent.
Bottom line, a few
days of spaceflight
can make certain bacteria
significantly deadlier.
Now I know a lot of
fiction says zombieism
is viral and not bacterial.
First of all, lots of
plagues throughout history
have been bacterial,
but OK, viruses.
Consider the "Walking
Dead." in that world,
every living person has
somehow already contracted
the zombie virus,
which lies dormant
until you die at which
point [ZOMBIE SOUND].
Where the virus
came from and how
everyone got infected though
have yet to be explained.
So consider this.
Preliminary evidence suggests
that the 3D structure
of viral proteins,
which dictates
in part how viruses
enter cells may
be altered in micro gravity.
Moreover, blood samples
taken from astronauts
during various stages of
spaceflight show reactivation
of dormant viruses
that they already
carry like chicken pox or
the Epstein-Barr virus which
causes mono-- all of which
suggests that viruses also
are more virulent in orbit.
Now this could be happening
due to changes in the viruses
themselves or because
space flight generally
weakens the human
immune system or both.
NASA is not really sure yet.
All I'm saying is
given what we do know,
it sounds like patient
zero on "The Walking Dead"
could have been an astronaut
carrying a distorted virus.
Now zombies aside, NASA
and other space agencies
research infectious
disease extensively.
But that research is
tricky because you
need to put people in space for
long periods to collect data.
And that takes years.
NASA also has thorough
quarantine sterilization
procedures to minimize germs
hitchhiking into orbit.
But you can never really get
stray microbes down to zero.
Take the Curiosity
rover, for instance.
To avoid contamination
of the Martian surface,
NASA went to great lengths
to sterilize the rover
before launch--
clean rooms, people
in bunny suits, the works.
But Curiosity was
still estimated
to harbor a few hundred thousand
microbes when it took off.
Considering you have
trillions of foreign bacteria
on or in you right now, a
few hundred thousand is tiny,
but it's not zero.
Plus, the future of
space travel won't just
be government space agencies.
If you fast forward
a few decades,
you're going to have an era of
space tourism or space hotels
where ordinary people are taking
vacations to low-earth orbit.
Once most space passengers
aren' t professional astronauts
anymore, you are going to
have a pretty big petri
dish up there with
lots of opportunities
for a hypothetical
zombie patient zero,
because the bottom line is
that infectious disease takes
on a whole new
dimension in space.
And dealing with that fact is
one of the biggest challenges
in establishing a larger
human presence in Earth orbit
and beyond.
So to recap, space flight
can strengthen and change
the operation of pathogens.
It weakens the body's
immune response.
And 100% sterilization
is impossible, even
in the cleanest of
NASA clean rooms.
Sound like a
plausible plot device
for a fictional,
previously unknown disease
gets a foothold?
Since our understanding of the
nuances of disease in space
is still in its
infancy, it's not
like anyone was in a position
to say its impossible.
I mean, other than
the reanimation part.
But why split hairs?
So what do you guys think?
Will the zombie
apocalypse start in space.
Should fear of
"The Walking Dead"
feature space flight
in its upcoming origin
story for the "Walking
Dead" zombie virus.
Let us know in the comments
along with any cool scenarios
you might have in mind for
a good, space-based zombie
apocalypse backstory.
I will report the best
ones on the next episode
of "Space Time."
Last week's episode was about
farting your way to the moon.
You guys had a lot to
say in the comments.
At the top, let me just
address all the comments
about our choice of
topic for this episode.
Look, this was all me.
I think farts are funny and
that they are a good vehicle
for explaining physics.
I also went to school
for more than 10 years,
published articles in
journals-- I like the ballet.
Go figure.
So let's look at some
of the physics questions
that this episode prompted.
Diarmuld Balfi asked,
"If I kept releasing gas
over several days,
wouldn't eventually
I pick up a lot of speed?"
In short, no.
The effects when you're
releasing that little mass
are basically additive.
And they come out from straight
up momentum conservation.
Even if you released a full
day's worth of gas every day
for a year, you would
still only build up
to a few millimeters per second
of speed-- just not very fast.
Now, say you wanted
to release decades
or something worth of gas.
At that point, the
total amount of gas
that you would
have released would
have been a non-trivial
fraction of your body mass.
And to compute
everything correctly,
you would have had to take
that loss of mass into account
and use a more correct version
of momentum conservation called
the rocket equation that
compensates for this.
Dariodario alluded to
the rocket equation
in that form of calculating
momentum conservation
in his comment.
TonyFalca asks, "Could you
not swim through space?"
There were a lot of responses
indicating no because there's
nothing to push against--
the same way you're
pushing against water on Earth.
However, David Shi made a
comment directing me to a paper
by an MIT physicist indicating
that in a curved space time,
you may actually be able
to do this-- actually have
reactionless was propellant.
I am going to read up
on this and make sure
that I understand it right.
But this could be fodder
for another episode.
And, finally, Remy
Porter commented
that he'd love to see his
farts accelerate to mach 4.
You and me both,
brother-- you and me both.
[MUSIC PLAYING]
And remember, rule number one
for the zombie apocalypse--
cardio.
