
Vibration overcomes gravity on a levitating fluid - bencoder
https://www.nature.com/articles/d41586-020-02451-w
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pfdietz
This reminds me a bit of quadrupole ion (Paul) traps.

These confine charged particles using just electric fields. This is not
possible with static fields (Earnshaw's theorem), but can be done with
oscillating fields, even with sensors to determine the positions of the
trapped ions.

[https://en.wikipedia.org/wiki/Quadrupole_ion_trap](https://en.wikipedia.org/wiki/Quadrupole_ion_trap)

If I recall correctly, the principle was also illustrated in Feynman's lecture
notes, where a vertical rod supported by a ball joint from the bottom is kept
from tipping over by rapidly moving the joint up and down.

~~~
pfdietz
"even without sensors"

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georgewsinger
Vibration can, in principle, be used as a propulsion technology, no?[1]

> Woodward’s MEGA drive is different. Instead of propellant, it relies on
> electricity, which in space would come from solar panels or a nuclear
> reactor. His insight was to use a stack of piezoelectric crystals and some
> controversial—but he believes plausible—physics to generate thrust. The
> stack of crystals, which store tiny amounts of energy, vibrates tens of
> thousands of times per second when zapped with electric current. Some of the
> vibrational frequencies harmonize as they roll through the device, and when
> the oscillations sync up in just the right way, the small drive lurches
> forward.

[1] [https://www.wired.com/story/mach-effect-thrusters-
interstell...](https://www.wired.com/story/mach-effect-thrusters-interstellar-
travel/)

~~~
netsec_burn
That drive would need extensive testing, because it violates Newton's third
law. Similar reactionless drives like the EM drive also warrant skepticism.
Occam's razor, it's more likely the tests measuring their thrust were not
accounting for a background element, even the article acknowledges this.

~~~
vertbhrtn
A levitating frog warrants even more skepticism, but it's levitating.

~~~
dekhn
No, the levitating frog is exactly what you'd expect if you had a strong
enough magnetic field.

[https://www.ru.nl/hfml/research/levitation/diamagnetic-
levit...](https://www.ru.nl/hfml/research/levitation/diamagnetic-levitation/)
"Lesson #1: Everything can levitate It is possible to levitate magnetically
every material and every living creature on earth. Molecular magnetism is
always present, although it is very weak and usually remains unnoticed. It
might give you the impression that materials around us are mainly nonmagnetic.
But this is not true. They are all magnetic. We call them ‘diamagnetic’. With
magnetic fields high enough you can levitate all diamagnetic materials. At our
lab, we develop and build magnets that have a very high magnetic fields. We
use it to investigate molecules and materials. And show the world a levitating
frog."

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kencausey
Previously:
[https://news.ycombinator.com/item?id=24362808](https://news.ycombinator.com/item?id=24362808)

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ta1234567890
In the next few decades, we'll start seeing all kinds of crazy applications of
vibration. There might be a physics and engineering revolution coming.

~~~
satori99
I have wondered about this too, after reading about other interesting
experiments with vibrating oil droplets a few years ago.

[https://www.sciencealert.com/these-bouncing-droplets-
behave-...](https://www.sciencealert.com/these-bouncing-droplets-behave-
strangely-like-quantum-particles)

------
vertbhrtn
My favorite example of these water experiments is sonoluminescence: a tank of
water is driven by a high-frequency acoustic transducer to create a 3d
standing wave, which forms a tiny bubble of air or other gas that, when
collapsing, produces a burst of light.

That tiny burst of light is still an unsolved mystery. Despite it's trivially
reproducible, there's still a range of competing theories that estimate the
temperature of that bubble from 2,000K to 20,000K (some researchers add a few
zeros there), and attribute the light to anything imaginable, including fusion
and the Casimir effect. Quoting Wikipedia: "the rapidly moving interface
between water and gas converts virtual photons into real photons."

