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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?
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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.
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And remember, rule number one for the zombie apocalypse--
cardio.