Scientists reverse the Casimir force to make things levitate.

This news item is short on details about the experiment, but if it pans out it could be quite significant as it appears to manipulate one of the forces that holds atoms together:

Professor Ulf Leonhardt and Dr Thomas Philbin, from the University of St Andrews in Scotland, have worked out a way of reversing this pheneomenon, known as the Casimir force, so that it repels instead of attracts.

Their discovery could ultimately lead to frictionless micro-machines with moving parts that levitate But they say that, in principle at least, the same effect could be used to levitate bigger objects too, even a person.

The Casimir force is a consequence of quantum mechanics, the theory that describes the world of atoms and subatomic particles that is not only the most successful theory of physics but also the most baffling.

The force is due to neither electrical charge or gravity, for example, but the fluctuations in all-pervasive energy fields in the intervening empty space between the objects and is one reason atoms stick together, also explaining a “dry glue” effect that enables a gecko to walk across a ceiling.

Now, using a special lens of a kind that has already been built, Prof Ulf Leonhardt and Dr Thomas Philbin report in the New Journal of Physics they can engineer the Casimir force to repel, rather than attact.

Initial applications are aimed at nanotechnology where the Casimir force causes no end of headaches, but they think it could in time be applied to larger objects including perhaps making a human levitate. Think of how cool you’d be zipping around on your official Harry Potter replica broomstick, but that’s still quite a ways off yet. Still, very cool stuff.

8 thoughts on “Scientists reverse the Casimir force to make things levitate.

  1. How the hell do you reverse a fundamental force? What did they do? They could only really change conditions, not the laws of physics.

    think it could in time be applied to larger objects including perhaps making a human levitate

    or human explode?

  2. Perhaps Scotty was wrong.

    Actually I am a bit fearful when scientists start pokoing around at the quantum level. I asked a science teacher once that when they started the first atomic chain reaction, how did they know it would self contain, and not create a fire ball of the atmosphere. Apparently the answer is ‘They didn’t’- best guess came in.

    Nano Bots were the next big thing a couple of years ago- able to disassemble molecules to reproduce. Scientist scoffed at those who were worried they would be out of control, but lets face it- it only takes one rogue producing identical (rogue) copies- once a minute. Thats 1,152,921,504,606,846,976 after an hour- buggers would be unstopable!

    Now they want to fuck around at the sub atomic level. They’ll be tears (and exploded scientists) before bedtime, you mark my words

  3. I’ve been looking up the casimir effect and have been struggling to find a decent explanation of exactly why the 2 things should be attracted.

    For sure, there’s van der waals attraction (field effect), and miniscule attraction through spin coupling (which is quantized), offset by steric repulsion (field effect), however that’s covered charge and spin effects, I see no other thing that can be coupled to cause this attraction.

    In short, until I see what else could be having an effect, I will consider these things the only reasons for a force to be acting between the plates. For now I will consider the casimir effect generally accepted bullshit that’s been aproved because it satisfied equations that might be accounted for by standard forces and is protected by a general lack of understanding (which is indicated by the lack of decent explanation of what it is or why).

    Sure it’s quantized in the equations, but so is spin coupling, and if casimir was truely a force all along, our equations for sterics, van der waals, and spin would all be out. Wikipedia stated that the casimir force was found to be within 15% of expectations, to me that is an unacceptable margin of error.

    The article about the levitation mentioned a lens – are we merely using light energy to break enthalpic interactions and increase pressure by thermal agitation? Heat up the air beneath you and you’ll be carried upwards by an upcurrent as in hot air ballons?

  4. Bahamat, y’know when you dive into physics questions, I usually sit back and let the dice roll.

    But I agree 100%; physics can do better (and does it every day). Let’s hope they get lots more time to test on this stuff.

  5. i bet some religious person will claim that mr. jeezus figured it out yeears ago. HAHAHA

  6. Patness: But I agree 100%; physics can do better

    A source of the problem is that people, inexplicably, are able to get through to the point of teaching on phonomenal rote memory (as they are with chemistry). Chemistry is compressed and physics more so, I (and probably many others) was turned off from physics as a main subject because my teachers used such a high density of terms they didn’t try to explain or justify, to the point of intimidating. I’ve noticed teachers (and students) who don’t understand themselves often never admit it, and suggest that desiring a better explanation means we’re too stupid to understand, or stupid for questioning what they take so religiously. Good teachers are absolute golddust, and questioning needs to be encouraged as a route to understand.

    p.s. another thing I disagree with is how the uncertainty principle is said to mean it’s impossible to exist still – it is impossible to be still because of zero point energy, but that’s an unrelated conicidence, the uncertainty principle implies merely that you don’t measure it as being still, and only because the light/electron beam you shine on it to measure it’s position transfers some energy to it.

  7. I (and probably many others) was turned off from physics as a main subject because my teachers used such a high density of terms they didn’t try to explain or justify, to the point of intimidating. I’ve noticed teachers (and students) who don’t understand themselves often never admit it, and suggest that desiring a better explanation means we’re too stupid to understand, or stupid for questioning

    As far as physics is concerned, an explanation of why science is the way it is would be a good foundation to work from. That is, explain it. Physics was one of those subjects I questioned to no end (even the Newtonian physics – the Normal Force never made sense to me except as an abstract to describe real phenomena, which, it turns out, is precisely what Physics was all about).

    But I’d be lucky if my teacher could explain that. 3 years of university to get her teaching degree and she didn’t understand the scientific method enough to explain it.

    another thing I disagree with is how the uncertainty principle is said to mean it’s impossible to exist still

    Seems like you followed a number of reasonable ideas to why the Uncertainty Principle fits known phenomena and makes sense.

    When I said physics can do better, I mean the 15% margin of error or whatever – that’s fantastioally more broad than the exactitude with which we have tested the other realms of contemporary physics.

  8. The Casimir force is not exactly a ‘fundamental’ force: we know from Quantum Electrodynamics that any body is subject to quantum vacuum fluctuations which cause the surface molecules of material bodies to behave as dipoles, and these dipoles interact between each other. In some cases -most known ‘real’ cases- the summation of these dipole interactions (the Electromagnetic Casimir force) is attractive. The theoretically possible existence of repulsive Casimir forces has been stated in the field literature for quite some time now. For example, if materials with certain exotic magnetic properties (extremelt high magnetic permeability) were used, the force is calculated as repulsive. To our knowledge, there is no material with m.p. sufficently high in existence, but theoretically, the repulsive solution exists. The Casimir force is highly dependent on the shape of the interacting bodies, and many several geometric setups have also been shown to (possibly) lead to repulsive forces. It is by changing the conditions that the force becomes repulsive. The actual force depends on the material conditions. This is true for any force. Additionally, there are also more general instances of Casimir forces other than the electromagnetic one usually (for historical reasons) labeled *the* Casimir force, e.g., the acoustic Casimir force, where the equations can easily lead to repulsive forces, which in fact have been realized experientally.

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