Things that have mass have a certain amount of gravity and will interact with other things that have mass. By rotating a city in space you would not create gravity, you would simulate it. Assuming your city was ring-shaped, and spinning fast enough, everything in it would feel a force pulling them outward, but it would be the centrifugal force, not gravity.
For most purposes, it would act in a similar way, but it would not be identical. For example, if you dropped something from very "high" close to the center of the ring it would not hit the ground directly below it. As the falling object traveled toward the "ground" the ground would rotate underneath it. This is sometimes called the Coriolis force. If you read Arthur C. Clarke's novel "Rendezvous with Rama" he describes a city that rotates to simulate gravity, and even talks about what its weather might be like.
Ryan : Gravitons are theoretical particles that would carry the gravitational force, the same way that photons light particles can be thought to carry the electromagnetic force. Gravity is very weak compared to the other forces in the universe, so its force-carrying particles are very difficult to detect. Nobody has ever detected a graviton, and the only way that we know of to produce them is to have mass, as I described above. So the only way that we know of to produce gravity uniformly from a surface would be to make that surface have a lot of mass!
I can't see how spinning anything in space using centrifugal force could work. Don't you have to have weight to do that? Otherwise the floor would just slip beneath your feet.
And if there was a wall attached to the floor, you would only be slapped by it. I only see it working if you had some sort of constant acceleration beneath you, pushing you in one direction to keep you upright. Ryan : All you need to feel centrifugal force is mass.
A brick has the same mass on the surface of the earth as it does in deep space. Weight is the force that something feels due to gravity: so the brick would have a much larger weight near the earth's surface than it does in deep space. Now that we have that out of the way, let's talk about the centrifugal force. I can see why you are confused: if I understand correctly you are picturing an astronaut floating inside a stationary space station and not touching anything.
When the space station begins to rotate, it seems like it shouldn't do anything to the astronaut, right? If there is nothing exerting a force on the astronaut, they will just float while the station rotates around them. But a space station is not empty. There is air, and as you say, there are walls and other obstacles. As the station begins to rotate, the air inside will begin to move with it, so even without any other objects, a slight push from the surrounding air would make the astronaut start to move.
Once the astronaut is moving, it is only a matter of time before they come into contact with the outer edge of the rotating space station which is soon going to be the floor. Now we need to think about how the centrifugal force works.
There is another way to think about it that I will describe here, which makes it seem like it's not a real force at all! Ok, so what is a force? A force is something that causes a mass to accelerate. We defined mass up above, but what is acceleration? The simplest definition is that acceleration is a change in how fast something is going or the direction that it is going. So, our astronaut had been nudged by something inside the space station that is rotating with the station itself, and the astronaut is now drifting along in some direction.
The laws of physics say that the astronaut will travel in a straight line with no acceleration until some new force acts. If you are an astronaut traveling in a straight line inside a round, rotating space station, eventually that straight line will intersect with the "floor". When it does, your body wants to keep traveling in a straight line, but the floor is in the way, so it gives you a nudge inward and in the direction that it is moving.
The floor exerts a force, which causes acceleration. You can probably see where this is going. As the astronaut gets bumped along by the rotating floor, eventually, they will be going at the same speed. But remember, acceleration is a change in speed or direction!
If you watched from afar, the astronaut would appear to be traveling in a curved path, around and around the circular space station. A station concept, to be assembled on-orbit from spent Apollo program stages. The station was to Because if you want to travel to another star system, you'll have to accelerate your ship to get there Unless you can shield yourself against those accelerations, catastrophe awaits you.
For example, to accelerate to full impulse in Star Trek, a few percent the speed of light, would cause to to experience over 4, g s of acceleration even if you took an hour to get up to speed. That's more than times the acceleration necessary to prevent the blood from flowing through your body: a bad situation no matter how you spin it.
This launch of the space shuttle Columbia in shows that acceleration isn't just instantaneous For a starship, versus a rocket, the acceleration would be many times greater, even if sustained, than a human body could withstand. Moreover, unless you want to be effectively weightless during the long journey — subjecting yourself to horrific biological wear-and-tear like bone loss and space blindness — you'll want some type of force exerted on your body continuously.
For the other forces, this is easily doable. In electromagnetism, for example, you could place the crew inside a conducting shell, and any external electric fields get cancelled out. You could then set up two parallel plates inside, and have a constant electric field, causing charges to be "pushed" in a particular direction. Schematic diagram of a capacitor, where two parallel conducting plates have equal and opposite This configuration is impossible for gravity, unless there's some form of negative gravitational mass.
There is no such thing as a gravitational conductor, and no way to shield yourself from the gravitational force. There's no way to set up a uniform gravitational field in a region of space, either, such as between two plates. The reason? Because unlike the electric force, which is generated by positive and negative charges, there's only one type of gravitational "charge," and that's mass-and-energy.
The gravitational force is always attractive, and there's simply no way around that. Instead, you have to do the best you can with the three types of acceleration — gravitational, linear, and rotational — available to you. The overwhelming majority of all the quarks and leptons in the Universe are made of matter, but The only way you'd be able to have artificial gravity, both to shield you from the effects of your ship's acceleration and to give you a constant pull "downward" without needing to accelerate it, is if somehow you discovered a type of negative gravitational mass.
All the particles and antiparticles we've ever discovered have a positive mass, but those are inertial masses, or the mass you talk about when you accelerate or create a particle.
We've demonstrated that inertial mass and gravitational mass are the same for all the particles we know of, but we've never tested this sufficiently for antimatter or antiparticles. So as people travel to the Moon or Mars, their pull toward Earth quickly weakens, which leaves them floating.
This might seem like fun. This weakens them. This can cut off hearing. Also, floating around in zero gravity makes you puke. And at least a few of the simpler tactics might not be that far off. The flow of electric current produces magnetism. All an astronaut would have to do is wear metal boots. The attraction between the metal and the magnet would help someone walk along the floor.
The work required to walk against a magnet might also limit bone and muscle loss in space. Fluids would still be able to collect in the upper body. And your stomach would still be awfully confused. Scientists could try to harness real gravity, McKinnon says. Everything with mass has gravity, she points out.
So one simple idea would be to have a lot of mass. Neutron stars , for example, are extremely dense. A teaspoon of neutron-star material might be enough to give us gravity, she says. Both of these exert vast amounts of gravity for their size.
But how could you contain a black hole — even a tiny one — in the middle of a spaceship? When you are inside a large, spinning object, you will feel a pull toward the outside wall. This is because of inertia. Your body is resisting the change in motion of the object spinning around you.
This force seems to pull us to the outside edge of the rotating teacup.
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