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Tractor Beam Created Using Water Waves
KentuckyFC writes The idea that light waves can push a physical object is far from new. But a much more recent idea is that a laser beam can also pull objects like a tractor beam. Now a team of Australian physicists has used a similar idea to create a tractor beam with water waves that pulls floating objects rather than pushes them. Their technique is to use an elongated block vibrating on the surface of water to create a train of regular plane waves. When the amplitude of these waves is small, they gradually push the surface of the water along, creating a flow that pushes floating objects with it. However, when the amplitude increases, the waves become non-linear and begin to interact with each other in a complex way. This sets up a flow of water on the surface in the opposite direction to the movement of the waves. The result is that floating objects--ping pong balls in the experiment--are pulled towards the vibrating block, like a tractor beam.
I'm fairly certain I duplicated this experiment in the bathtub as a child (and maybe even as a teenager).
In space, no one can hear you steam...
Do not look into laser with remaining eye.
No beam. Less space than a Nomad. Lame.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
If the backwards flow of water is a result of a complex system of causal interactions, they couldn't have come to the conclusion that this would work based on what they already knew. So how did they discover it? Was it an accident? If not, can one of them look into the future? This is a pretty awesome result if it didn't depend on coincidence.
Large scale: cleaning up oil spills.
Small scale: Device for more effectively scooping up dirt and dropped leaves from a swimming pool.
If you can compress space to achieve warp speed, you can then also compress space to create waves in the vacuum.
That's no pool...
This thread is useless without video.
Bet this started out as a thought experiment on how to get chicks to stand close to them.
You don't compress space, you bend it.
And, no, I don't actually know what that means either. :-P
Lost at C:>. Found at C.
Anti-gravity! But how does one perturb space-time? We can't even detect gravitational waves much less create them. I don't think we will solve this one overnight
I agree, in todays world, such claim need to be backed by something like a video...
...that's a space heater!
Do not look into laser with remaining eye.
Gravity bends space, although always in the same basic way. (I think)
So lets imagine there may be some other way of bending space...
Do what thou wilt shall be the whole of the Law
it's a space station.
Gravity is what makes a floating object move forward/back when a wave passes under it. Waves themselves would just make floating objects bob up and down in the same spot, without gravity. And it only works because the water has a surface for the object to float on top of, because as a wave passes under the floating object, the object will want to slide down that surface, forward or back, away from the wave's peak. (Forward or back, depending on where the wave's peak is and which direction the water is inclined at that side of the wave, obviously; to get any net movement, you need asymmetrical waves.)
In a volume filled with fluid in the absence of gravity, none of this is going to happen.
..with TRACTOR beams!!
If only we had some sort of robot that could bend things for us
rewriting history since 2109
Bite my shiny metal ass.
However, when the amplitude increases, the waves become non-linear and begin to interact with each other in a complex way.
There's the rub: photons don't become non-linear. Unless you pump out energies where spontaneous matter-antimatter pairs are created from vacuum. But whatever you are going to pull on with a beam of that kind will not arrive in good shape.
Gravity bends space, although always in the same basic way. (I think)
So lets imagine there may be some other way of bending space...
What?!?! Next you are going to tell me that gravity can somehow draw one object towards another. Preposterous!
Does it only happen when I have 3 walls that the waves can bounce off of? Because that would not work in an open water setting, only in enclosed settings. It makes me think of pool (billiards) where you could make a ball come toward you by hitting the que off two walls then into the back of the target ball.
If you can repeat it from arbitrary points and arbitrary distances then you start to have something useful.
If you can repeat it with other wave sources then it gets more useful.
I refuse to sign
Since when does "not yet detected" = "there is no medium in space"?
Pushing is nowhere near as effective in cleanup operations which is why vacuum cleaners suck instead of blow (and very early victorian models did). Suction concentrates the particles in a fixed location whereas blowing scatters them.
I wonder if this can be used for oil spills and other water-pollutants...
Rip currents pull things out to sea opposite the flow of the waves. It seems that Rip currents or riptides are a much simpler and unrelated effect with regard to this phenomenon, but I wonder if it served to pull the researches in the right direction? Pun intended.
FWIW, this paper talks about doing this with light (in the context of micro-manipulation). Doesn't look like we will be using this for any star-ship sized objects in the near future...
The basic idea is that you use a light with a specific profile to stimulate the object you want to attract in a way that causes a scattering field such that there is a net force backward to the emitter (it only works if the amount of net forward momentum of the light is relatively small compared to the scattering).
The water stuff referenced by this article works on a completely different principle, though as described here.
They are similar in that they originate with a wave generator, also hitting the target at a glancing angle is a way to achieve the necessary conditions and both provide a net attractive force (aka tractor beam), but the physics is totally different.
Gravity bends space, although always in the same basic way. (I think)
So lets imagine there may be some other way of bending space...
You don't bend it, you fold it.
Of course, you need a supply of the spice melange, first.
OK - so reversing polarity DIDN'T work - - - NOW go to MAX POWER (Wil Wheaton's last words . . .)
redneck geek
All you need is a computer controlling an actuator and a video camera to track the objects, then you just evolve the solution. In fact you could evolve a full set of motion vectors and then combine them in sequence to drive the object around at will. However this would only apply to the specific environment defined by the test tank and it may not turn out to be a very efficient way of moving anything around, then again if it can scale down to the scale of biological cells it could be very useful for cell sorting, labs on chips etc.
d@3-e.net
She's gone from suck, to blow!
How is the Riemann zeta function like Trump rallies? Both have an endless number of trivial zeros.
Next time maybe don't try to fit Worf's cock in your mouth all at once?
There is. Acceleration. Accelerate hard enough and all sorts of strange things happen in your wake, the trivial example being Unruh radiation.
"... and more and more now there are all kinds of electronic goodies available" -- Pink Floyd 1972