I have spent a long time thinking about various scientific subjects and one of the subjects I think about a lot is artificial gravity. If humanity continues to search the stars, then there will need to be some form of gravity on our spaceships to make that travel more, "human friendly" or most of space travel will need to be done by computers. Without gravity near that of the Earth's pulling down on the human body, long-term exposure to a lack of gravity will eventually cause the human body to start to become ill. Bones become weak without gravity. Muscles, especially the heart muscles become weak. Digestive systems are impaired as they use gravity to aid in their processes.
So gravity is very important for humans and some sort of artificial gravity will need to be created to for humans to do long-term space travel.
One of the ways scientists believe they can create artificial gravity is by creating a ship with a torus (doughnut) shaped hull and spin that hull so that the ship spins like wheel on a car. Centrifugal force is supposed to be created and an object in the spaceship will be forced against the hull. The hull itself feels like it is pushing against the object (centripetal force) and if this object is a human being, it feels like gravity has been created. The faster the wheel spins, the stronger the centripetal force (the push against the feet of the human) and the more the feel of "gravity".
If this is confusing, think of a clothes washing machine.
The washing machine has a cylinder inside it that contains the clothes and this cylinder moves depending on the washing cycle. In the last cycle, the drying cycle, the cylinder moves at its fastest and if you looked inside while this was happening, the clothes get pinned along the inside of the cylinder. Since there are holes in the cylinder, the water get flung off the clothes through centrifugal force but the clothes stay pinned to the cylinder wall as they cannot fit through the holes.
If you take that scenario and expand it to the size of a spacestation, the theory is that humans will be the "clothes" and the cylinder is the interior of the spacestation.
Simple right?
However, there is one thing missing in space that the washing machine on Earth doesn't have: gravity.
What is happening in the washing machine is that is it manipulating gravity to cause the clothes to become pinned on the inside of the cylinder. Gravity is the force that is pulling the clothes down. That is why when the cylinder is moving slowly, the clothes tumble along the bottom of the cylinder. As the speed picks up, the clothes tumble higher and higher until the speed of the cylinder is fast enough to move the clothes faster than gravity can overcome the clothes and pull them down. The speed of the cylinder redirects gravity and uses it to pin the clothes to the inside of the cylinder. Without gravity, none of this is possible.
So, if someone builds a spaceship like a large doughnut or wheel where astronauts can walk around in, parks the spaceship in orbit or even somewhere in space, spins this "wheel" at a fast rate, there will be no artificial gravity created to pin astronauts to the floor of the spaceship. What will happen is the spaceship will spin around the astronaut.
Aha! some scientist will say, if the astronaut started with his/her feet firmly planted on the "floor" of the spaceship (perhaps tied down) when the spaceship was first started spinning, then the inertia of the spin will be transferred to the astronaut and he/she will feel gravity.
Sorry, this won't happen.
The astronaut will get pulled along with the wheel and will be in sync with the wheel but the astronaut will not feel "gravity" as there is nothing to pull the astronaut towards the floor. He or she will feel the wheel spin, but when the spaceship gets up to speed, and they unhook themselves from the floor, they will still float away. The act of spinning doesn't pull the astronaut towards the floor, it just spins.
If this could actually work, then why aren't astronauts in the International Space Station currently in orbit not pinned to the side of a wall or the floor? They are spinning around the Earth at roughly 17,240 miles per hour, a speed that should be enough to create an artificial gravity through centrifugal force, so why are the astronauts still floating?
The answer is, there is no gravity to manipulate so once the ship gets up to speed and is in a stable orbit, the lack of inertia causes the astronaut to float freely in space. The space station and the astronaut are both moving at the same speed, so without gravity or inertia, there is nothing to keep the astronaut from floating where he or she pleases.
So there you have it... any movies that you see where they spin a spaceship or space station in order to create gravity is wrong and if anyone is dumb enough to create a spaceship and put it into space with one of those "wheels" to spin and create gravity, you will know the result well before they do.
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