We all know that on *The Enterprise, The Millenium Falcon[i/], Imperial starships, and just about any other spacecraft the inhabitants thereof walk about oblivious to the fact that they’re in zero-gravity.
Now, we’ll assume that The Empire and The Federation have both figured out a way to create gravity in space. As for the crew of The Millenium Falcon; well, it was too expensive and time-consuming to work zero-gravity into the sets.
Anyhoo, back on Earth, it’s pretty-much impossible to defy gravity for any length of time. Sure, you can resort to crude means, such as strapping on a special suit and hovering about for a few minutes in a special room while a turboprop blows you into the air, or hopping aboard the Vomit Comet, but that’s now what I’m talking about.
I seem to remember that in Event Horizon there was a scene in which all manner of stuff was floating about in weighlessness until someone commanded “turn on the gravity!” and with a flick of a switch everything fell to the floor.
Now, is this possible, even in theory? That is, is there any way imaginable to create gravity in space and also to create a sustained zero-gravity environment on Earth?
You can create gravity (sort of…more on this in a moment) but you cannot defy gravity by shielding yourself from it.
Gravity is the result of mass. As long as you have two masses or more they attract each other. If you wanted gravity aboard your ship via this method you’d need the equivalent mass of the earth aboard your ship which would make moving your spaceship very difficult.
The other means of creating gravity is via acceleration. As long as your ship accelerates you will feel a force acting on you. Accelerate just right and you can mimic a force of exactly 1g so it feels as if you’re in an earth equivalent gravity. The idea of acceleration and gravity being related is called the Equivalence Principle and was thought up by Einstein. The idea is if I put you on a ship and accelerated you there are no experiments you could perform to distinguish between a force due to acceleration and the effects of gravity. Pretend you were born on this ship and it was windowless…you never saw outside…you’d think you were in a gravity well and not moving at all. However, this only works if you are constantly speeding up. Presumably your ship would run out of fuel someday. When that happens no more acceleration and you’re now floating around your spaceship (no more ‘gravity’).
As for shielding yourself from gravity forget it. At least for now since no one knows how. Gravity is by far the weakest of the four forces (strong nuclear, weak nuclear, electromagnetic and gravity). Think about it…two little magnets can be hard to pull apart but it takes the mass of the entire earth to make the effect of 1g you currently feel. The interesting thing is, though, that while gravity is the weakest force it is also the only force you cannot shield yourself from. Hence no antigravity rooms or antigravity sleds.
I think the OP was more about ‘switchable’ gravity, the kind of thing they have in scifi movies to avoid having to do too much zero-g, which often looks mighty hokey.
Right now, the only way we know of to produce an actual gravitational field is with mass, distorting spacetime. In order to have a more technological solution (like in the movies) we would probably need a quantum theory of gravity, something a little easier to exploit, and nobody’s managed to prove any of the quantum gravitational theories yet.
If we could come up with a gravitational theory, and isolate gravity quanta (gravitons), then we might be able to manipulate them to create artificial gravitational fields. As an interesting side effect, if we have a machine that can create gravity, we also have a machine that can accelerate the ship – that’s one big oversight in Star Wars: all that ‘repulsor lift’ technology would be a much cleaner, cheaper way to drive a starship than whatever propellant-based system they’re using.
So IF the quantum gravity theories pan out, there may be a possibility of gravity machines someday, and even inertial drives based on the same technology.
General Relativity can be interpreted to mean that gravity is the same thing as spacetime…so there is no escaping gravity at all (there’s always some gravity present, no matter how weak).
But let’s speculate for a moment…taking a Quantum Mech. view of things…perhaps there is a way to generate or control gravitons (if they even exist).
I’ll guess that this can’t be done & the best way to simulate gravity is through acceleration (linear or rotational).
Yes, it would, if it is in a zero-G situation as a whole.
There’s a carnival ride that my niblings and I almost got ill on. It’s a 20’ metal cylinder that spins on a vertical axis. You feel as though some gravity source is holding you to the wall, but you still feel something pulling you down to the ground as well.
There’s another ride that I never had the courage to try. It’s similar to the one I mentioned above, only about twice as big and it spins quite a bit faster. It also has more safety equipment: individual cells w/ hand grips. When it gets up to speed, the whole cylinder gets tilted up by a boom attached to the axis. Soon, the axis is completely horizontal, and those in the cylinder are kept from falling strictly by centrifugal “force”. (note the quotes)
I asked some of my friends about their experience riding it. They said the freakiest part was when they’re ascending. They start to feel real gravity lessen the effect of the centrifugal force, giving them the slightest feeling that they might just fall out on the next trip to the top. Of course, they never did.
AWB, I’ve been on both of the rides you mentioned. The second one is very cleverly engineered - it spins just fast enough to keep you in place, so you always have the feeling that you’re going to fall when you’re upside down. BTW, I think the chains are more to give the illusion of safety, I don’t think they’d actually do much if the ride were to suddenly stop spinning (not that that could happen).
I love that ride. And force is correct in this case, but not centrifugal. Centripetal force is pulling the individual cars inward. Newton’s third law gives you an equal and opposite force outward because of the way you’re sitting.
(I live near probably the best amusement park on the planet).
Now, as to defying gravity…
It’s been done. Don’t ask me to explain it, I don’t know that much physics. But they have used extremely strong magnets for a while to levitate superconducting disks. Recently they’ve been able to use even stronger magnets to levitate non-conducting objects (as I recall, one of the test subjects was a live frog).
Now, this is not the same as a production of anti-gravity. This is the use of one force (electromagnetic) to counter another (gravity). But hey, it levitated a frog.
When considering the foolishness of “switchable” gravity in films like Event Horizon, one has to realize that the supposed future technology depicted in these films may not currently be encompassed in our theories about the universe, and may be implemented in the film more for convenience or aesthetics and whiz-bangery than to depict real scientific scenarios. Sure, it would take a huge amount of mass on board the ship to create gravity (according to current theories), but the ship in Event Horizon had a device that could create black holes as easily as your Mr. Coffee does its work in the morning. Sure, even in that future state of technology, the black-hole machine had a few bugs :). <cliche>It’s funny how a lot of “inconceivable” science fiction sometimes becomes science fact </cliche>.
Imagine the ramifications of that? “Oh, great, Steve left the black hole machine on all night, and everything in the office got sucked in and destroyed. Thanks a lot, Steve! It’s not like I had end-of-month reports due or anything.”
[pet peeve]Centrifugal force is a perfectly valid term for what a person on a Rotor or similar ride experiences. From the (accelerating) frame of reference of the person on the ride, it behaves exactly like a real, gravity-like force is holding him onto the side of the ride. If you’re in an inertial (non-accelerating) frame, then you don’t see a person being pulled onto the wall, you see a wall pushing a person to move in a circle, and that’s the centripital force.[/pet peeve]
I’ve seen videos of the levitating frogs… One of my professors was involved in those experiments. It actually doesn’t involve the familiar ferromagnetic effect which acts on iron, but on a weaker effect called diamagnetism, which causes some substances (including water, and thus, most organic matter) to be repelled by a magnetic field. This can be used to simulate zero-G, to a degree, but as LazarusLong42 points out, it’s not really nullifying gravity, just countering it in a rather creative way. This effect could, in principle, be used to simulate gravity on a spaceship, or to ease the acceleration of liftoff, but in practice, we don’t have any magnets nearly big and strong enough to levitate a whole person, and for the forseeable future, spinning the ship will be a lot easier.
It’d be similar, though not exactly the same. Depending upon the radius of the cylinder, you might have very obvious effects. Dropped objects, for instance, would not fall straight down, but would drop at an angle. Climbing up in the spinning frame of reference, the centrifugal force would fall off much quicker than the equivalent gravitational force.
If gravity turns out to be a force similar to electromagnetism, or if it turns out that space can be warped by means other than the presence of matter, I don’t see any reason why at some point in the future there wouldn’t be a theoretical way to generate a gravity field, the same way we can easily generate magnetic and electrical fields now.
If you could generate a field of some sort that could bend space, you could do all kinds of neat things:
[ul]
[li]counteract gravity (create an inverted field that exactly matches the strength of whatever field you’re in, which would make moving really easy: just float your stuff to the 32nd floor of your apartment high rise[/li][li]easy and clean (depending on the power source for the field generator) propulsion[/li][li]things like a star trek “structural integrity field” put into cars & planes and such, enabling them to be built out of pretty much anything…maybe styrofoam. reinforced with a field as strong as you want, you’d have a super-light, super-sturdy vehicleacceleration limited only by your power-generation ability: fighter pilots would no longer need G suits, because you could sync the field generator with the controls and exactly balance the maneuvers with an inverted gravity field…no more blackouts, etc.[/li][li]In fact, acceleration due to artificial gravity could eliminate high-G effects altogether, since the pilot would be essentially freefalling toward the apex of the field (shape it like an egg, space curved more in front of you, less behind you. you’d fall toward the pointy area where space is more curved, but the egg would move with the plane/ship/whatever, since that’s where it’s being generated)[/li][li]Who knows…maybe you could even have almost-free energy: generate a really high-G field around a piezoelectric device (kind of like a quartz watch) to help power your field generator recursively.[/li][/ul]
Yeah, it sounds silly, even ridiculous, but then so did running a mile in under 4 minutes. So did regular commercial space flight, and so did computers and the internet.
Wasn’t it Douglass Adams in the Hitchhikers Guide that wrote something in the story to the effect that it’s completely possible, if say, you just threw yourself down at the ground and missed???
heh. Not that I’m willing to try it myself.
Don’t they use elecromagnetism on board the space station and shuttles now for smaller things though? or is everything bolted down or floating around?
HAHA yeah, but you can’t miss on purpose…it has to be accidental. Meaning you have to MEAN to hit the ground. No thanks. My luck, I’d hit my target 100% of the time. sheesh.
What happened to rotating space stations? When I was a kid, all of the SF writers postulated that future space stations would be ring-shaped affairs, turning on a central axis. Obviuosly, this would offer simulated gravity to the astronauts withing. Now, the International Space Station (if it EVER gets built!) will look like a bedspring. I thoufgt zero-G was bad for human health (calcium loss from the bones)-why was the rotatiing space station idea thrown out?
I’ll have to dig it up, but I remember reading about this in a Montreal newspaper. I was there over Labor Day weekend, 1996, so if that paper has a good on-line archive, I can probably dig it up. I know I made a copy of the article, but I obviously don’t have it here at work. I’ll look for it on the web and at home.
To summarize, it involves spinning disks that were cooled close to absolute zero. The way the scientists did it (as I said, I’ll try to dig up the details), they measured that the force of gravity was weakened above the disks.
I remember reading something about this also. I certainly did not read it in a Montreal newspaper, though, so maybe other news organizations (CNN.com?) would have the story in their archives also. . .