artificial antigravity

Mice Levitated in Lab
Scientists working on behalf of NASA built a device to simulate variable levels of gravity. It consists of a superconducting magnet that generates a field powerful enough to levitate the water inside living animals, with a space inside warm enough at room temperature and large enough at 2.6 inches wide for tiny creatures to float comfortably in during experiments.

The researchers first levitated a young mouse, just three-week-old and weighing 10 grams. It appeared agitated and disoriented, seemingly trying to hold on to something.

"It actually kicked around and started to spin, and without friction, it could spin faster and faster, and we think that made it even more disoriented," said researcher Yuanming Liu, a physicist at the Jet Propulsion Laboratory in Pasadena, Calif. They decided to mildly sedate the next mouse they levitated, which seemed content with floating.

I wonder if this would actually feel like freefall? I guess it would, since all of your tissues would be being lifted simultaneously, including in the fluid and hairs inside your semicircular canals.

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35 Responses:

  1. ultranurd says:

    Sounds like a good start to a Secrets of NIMH remake.

  2. mackys says:

    > since all of your tissues would be being lifted simultaneously, including in the fluid and hairs inside your semicircular canals.

    You might feel like you were upside down. Since it lifts water, all the fluid in your ear canal might go to the top...

    • Yeah, I would guess some bits of you, the ones that contain the most water, would be lifted more powerfully than others - e.g. blood would probably feel a stronger pull than bone. Having your skeleton (mostly) lifted up by your blood seems like it would feel pretty weird.

      • mackys says:

        Freakin' shame that making one of these things big enough for a person would be almost impossible. :P

      • jwz says:

        I guess it depends on whether the magnetic field is providing upward acceleration to counteract gravity, or whether it's trapping the water molecules in a more-or-less stationary position.

    • wisn says:

      My intuition is that the fluid in your ears would be lifted with the same force as the rest of you, so your sense of balance isn't reversed. Intuition ain't science, though, so I demand a supermagnet that can make me hover.

    • wisn says:

      Now that I've thought about this... Consider our experience of Earth's gravity, where the falloff of gravitational effect between your feet and your head is so small it's barely measurable. Since the thing making you hover is very close to you and intensely focused, there would be a pretty drastic falloff in effect over distance.

      So if you're right side up over the magnet, the water in your ears are less affected than the water in lower parts of your body, so your sense of balance reports that you're upright. And if you're upside down and your head is closest to the magnet, the water in your ears would push upward (towards the bottom of your ears), and your sense of balance would report that you're upright.

  3. I don't know if it would feel like freefall, as you're not falling, more "floating". With freefall, you're still feeling gravity pulling you at 9.8m/sec^2.

    I imagine this would be way more comfortable than riding The Vomit Comet

    • decibel45 says:

      Yeah, there's an unmistakable external force being exerted against you in freefall. I doubt this would feel the same since the force would be coming from within.

    • jwz says:

      No you don't. When you are in freefall, there is no sensation of gravity because all of you is falling at the same speed. With your eyes closed and no wind (atmospheric drag), you wouldn't know which way was down, because the hairs in your ears are moving randomly, and if you let go of your arm, it would not drop faster than the rest of your body.

      There is no difference between what happens when skydiving (prior to reaching terminal velocity due to drag), the parabolic path of the vomit comet, and being in orbit on the space station. All of these are still technically "freefall" while deep within Earth's gravity well. Remember, the ISS is only 200 miles up (2% of the diameter of the planet). You'd have to be a lot farther out in space for the force of gravity to be significantly reduced. "Orbit" just means "falling over the horizon."

      • There is no difference between what happens when skydiving (prior to reaching terminal velocity due to drag)

        Eh, to be pedantic I'd say this only holds at the very beginning of a skydive; when atmospheric drag is contributing half a gee of counterforce, you'd feel half your normal weight (in your internal organs, anyway -- the force distribution is very different from when you're standing on the earth's surface) but still be accelerating at 5m/s^2 and quite a way away from terminal velocity.

        For the reasons you mention here, "microgravity" is a bullshit term and should be abolished. Gravity's working just fine, it's just there isn't a big stupid planet in your way.

        • jwz says:

          I guess I assumed that acceleration due to gravity in one atmosphere (for something big) wasn't really that far off from acceleration due to gravity in a vacuum. Is it?

          "Remember, the enemy gate is down."

          • Uhh terminology mismatch here. Acceleration due to gravity is constant for our purposes.

            Net acceleration on the other hand is reduced by drag. At terminal velocity, by definition, the drag force is equal to the gravity force and there's no net acceleration. So as V goes from 0 to terminal, net acceleration goes from 1g to 0g.

            • t0rque says:

              This is exactly what I was figuring out how to say as I read the comments.

              This is why I don't think it'd feel like terminal-velocity freefall, but would feel like start-of-skydive freefall.

              • decibel45 says:

                Actually, that's one of the interesting things about jumping from a plane; you're starting velocity is already at least 80MPH, if not more (normal terminal velocity is ~120MPH). When you jump from a plane, you don't actually get a sensation of falling, because you're already moving at pretty close to terminal. Your velocity vector just changes direction.

                Now, jumping from a stationary platform is a different story. I've never done it, but I've heard you do get a feeling of falling. Though I think what's much weirder to skydivers is that you can't fly your body for several seconds; you have virtually no control. I expect I'd notice that a heck of a lot more than a falling feeling.

      • decibel45 says:

        Heh, my skydiving experience tainted my vocabulary. Please replace my references to freefall with 'terminal velocity'.

    • gfish says:

      Having ridden it twice, I doubt this would be as comfortable as real freefall on the Vomit CometWeightless Wonder. There is no way the acceleration is evenly applied, due to differences in water content and magnetic field strength. You might be floating, but I'm sure you would still feel pressures from this. In contrast, the lack of sensation when in freefall is amazing. There are really no physical sensations, not even the giddiness you feel when you jump on an elevator, just psychological effects. For me, any direction I looked in felt like down, like looking down the side of a tall cliff. Every dimension was perceived as depth.

      Now, it's very possible that this would be more comfortable than the full experience of riding the Vomit Comet, where you're forced to wear thick nomex flightsuits and sit forever on the tarmac in Houston in a plane that can't be air conditioned until it's in flight. Then, when the parabolas start, you're shifting back and forth between 0 and 2 gees every 90 seconds or so. It's really the high gee sections that tend to make you nauseous, as any movement of your head then will spin up you inner ear fluids in dramatic ways your body isn't designed for.

      That said, I still want a human-sized model. Freefall is fun.

      • There is no way the acceleration is evenly applied, due to differences in water content and magnetic field strength.

        In fact, you'll be held up by your full bladder. Fun!

  4. lionsphil says:

    Awesome. Install this in the deck plates, and we'll have artificial gravity yet.

    And, er, presumably wipe out any kind of magnetic storage within a five mile radius.

  5. legolas says:

    As for space applications, turning this around with the magnet at the 'top' would provide the artificial gravity that all the SF spaceships have!