Hey, Vsauce. Michael here.
How many people are in space right now dot com tells us that the answer is 6. Ever since the first person reached outer space 52 years ago, more than 500 humans have left Earth and they've gone as far as the moon, an impressive distance. I mean, space
stations, which we use in outer space today are way cool, but to scale they only orbit about this far away from Earth.
Whereas the Moon, where Apollo astronauts went, is way out here.
For the last twelve years, there has been a continuous and
uninterrupted presence of humans living in space.
Different people at different times, ever since November of 2001.
But so far, all of us, every human who has ever existed was born right here on Earth. Of course, Earth is a giant
collection of matter that got together in space, held together by its own gravity, so technically, we were all born in space.
But I wanna talk about outer space.
What is our relation to it and within it? How suited is our biology for the
larger universe we were born into? More specifically, if you were born and raised beyond earth, what would you look like? First things first.
Where is outer space?
Well, outer space happens to be about one hundred thousand meters above your head. At that point the atmosphere is so thin that in order to achieve lift, an
aircraft has to travel at a speed so quickly that that speed is the same as an orbital speed.
An orbital speed is a speed that is so fast, even with no lift, even while falling you don't, because the earth literally curves away from you as fast as you fall towards it. This is what astronauts in
the International Space Station are really doing. They're falling. It's a common misconception
that astronauts float around weightless in space,
because there is no gravity there. But there's plenty of gravity.
In fact, there's pretty much the same amount of gravity operating on them that there is
operating on you right now while you watch this video.
Believe it or not, if we build a tower all the way up to
where the International Space Station orbits, 370,000 meters high, and you walked out onto the top of that
tower, it would feel kind of like this. You would just be walking around like I'm walking right now. You wouldn't feel that much different, but the International Space Station
would be whizzing by at 17,000 miles per hour.
It has to, because they are falling. So to say that
astronauts float around in orbit, because they are experiencing zero gravity is very misleading.
Really, what they are feeling is Zero-G, where G is accelleration felt as weight.
G hurts so good, because gravity's limiting influence insures that we develop correctly and healthfully. After all, it is what we were born to thrive in. So asking what a human would look like, if conceived gestated, delivered and raised in orbit would look like, requires a discussion of weightlessness. Realistically, people building colonies
on planets beyond Earth or traveling through space for long
periods of time, who expected new humans to be born, would
utilize technology that helped mimic conditions here on earth. But until artificial gravity is
perfected and can be easily implemented, it's important to understand the effect
weightlessness has on our biology and other things.
For instance, in a zero-g environment hot air doesn't rise.
So a candle flame is not shaped like a stretched ball of glowing gas that's drawn upward. Instead, it's just a round ball of hot gas. We are not sure we can make babies in space. The logistics of merely
hugging are difficult enough. A recent invention, called the '2suit',
might make it easier. The 2suit provides effortless intimacy
in weightless environment, such as outer space or on planets with low gravity. But will it be enough to ensure that
conception happens? The enzyme responsible for stopping the
movement of a sperm cell's tale doesn't work very well when they're at zero-g. In space, sperms swim faster.
One thing we know about babies inside mothers in space involves the development of the vestibular system. Canals in the
inner ear that use the flow of fluid to determine movement, up versus down and balance. In a zero-g environment the fluid in the
vestibular system just floats around. It's confused.
And this can lead to motion sickness, visual illusions and disorientation.
It's called spaced adaptation syndrome and it
affects about 50 percent of astronauts.
Confusion about motion can make you vomit, carsick, seasick, zero-g sick, because of survival.
It's believed that motion sickness, a confusion about acceleration, is similar to the effects caused by the
consumption of poisonous plants, in which case vomiting can save your life. Pregnant rats taken to space give birth to babies back on earth that
struggle with directions. Unlike rat babies that gestated here on earth, the ones that gestated in space have
trouble writing themselves when thrown into water. They do tend to be better at processing
orientations common during weightlessness, which is a good sign for humans gestated, born and raised in space, but it's some of the only good news. Vestibular fluid isn't the
only fluid to be affected by a zero-G environment.
All of your body fluids are. On earth, gravity pulls those fluids down, but in orbit, the fluid is free to evenly distribute, giving astronauts their characteristic
bird legs and puffy faces. Cosmetically it's kind of a bummer.
And all of that new fluid pressure in your face can compromise vision. Of 27
astronauts studied after long space flights nine had fluid expansion around the optic nerve, 6 had eyeballs flattened in the back by fluid pressure and four had bulging optic nerves. More fluid pressure in your head causes
an errant message that your body must have too much fluid.
So the bodies of zero-G travelers respond by producing less blood. Astronauts can lose
up to 22 percent of their total blood volume while in space, leading to weaker atrophied hearts.
Away from Earth's protection, radiation from the Sun, and the rest of the universe, is incredibly dangerous and we're still
not exactly sure how to best guard against it. Mice exposed to levels of radiation
expected during interplanetary journeys showed signs of different brain blood
flow and larger plaques of the type found in patients with Alzheimer's.
Psychologically, feelings of isolation in space,
thinking about just how far away you are from the rest of humanity can affect you physically. Scientists
working at the South Pole have developed compromised immune systems with fewer T-cells.
As for the shape of your body, fully grown astronauts in orbit, no longer pressed down by earth typical g-force experience spinal expansion, sometimes growing by as
much as 3 percent before they come back to Earth.
A 6-foot-tall human can go to space and come back as a 6-foot 2-inch tall person.
Without usual and necessary stress, bones in space atrophy at a rate of
about one percent per month.
Given enough time, total bone mass lost can be as high as 40 to 60 percent. And when weightless, you don't need as
much muscle strength to move around. This causes the muscles of
people weightless in space to atrophy. Those that you use to fight gravity can
shrink 5 percent per month, for total muscle mass loss of 20 percent. It's all kind of scary and sad. But don't bother crying over it,
because without 1G to pull them down, tears don't work the same way in space. Astronaut Chris Hadfield makes excellent
videos about how things happen differently in orbit. For instance, tears just pool
upon your face due to surface tension. In space you can cry, but as he says, the tears don't fall.
We know that these problems exist for adults in space.
Theoretically they would affect developing children in space even more so. Parallels have been drawn between the
way a child skeleton would likely develop in orbit and diseases that cause weak and soft bones here on earth.
Bones that break and heal according to different forces than the
typical downward ones, like Rickets. It's tenable to say that
without proper precautions, exercise and care, like adult astronauts already take, children developing in space could look like this. Not because of Rickets or a lack of vitamin D, but because the usual forces and active
use required for healthy bone development just wouldn't be there.
Added to the other threats, imagine a body shaped like this but with thinner legs, thin, weak muscles, a puffier face, poor eyesight and a higher than
usual proclivity to dementia later in life. Doesn't sound very good, does it?
Remember though that a lot of this is speculation.
Few studies have been done on the topic and few are planned for the future.
We don't even know if a healthy fetus can develop in the first place or if conception can even occur in space. When I think about how little we know
about our bodies and how our bodies might grow and
develop in the larger universe beyond earth, I like to think about plankton.
These little guys live in the ocean and they exist in staggering numbers. Many varieties are too small to even see individually, but collectively they can be seen from space. It's estimated that there are more
plankton in the oceans of Earth than there are stars in our galaxy.
More plankton on Earth than there are galaxies in the observable universe.
And these guys wonder around at the whim of ocean currents. They're wanderers. In fact, they get their
name from the Greek word for wanderer, a name that they share with objects seen wondering in the sky.
Planets. Plankton on a planet.
Wanderers on a wanderer.
Maybe, like ocean plankton, we humans are
destined to wander far and wide eventually also becoming more numerous than the stars in our galaxy.
It's within the realm of what we can achieve. But before we start feeling too excited, too proud, keep in mind that we know very little about how our bodies grow and develop outside of this wanderer, this planet. And even though we know a lot of older words that sound like body, fundamentally we don't even know why we
call these things bodies in the first place. And as always, thanks for watching.
