Physicists solve Casimir conundrum | Hacker News Reader

Physicists solve Casimir conundrum

physicsworld.com

62 pointsColinWright18 comments

Can this be used to generate energy? Are there any practical applications to the Casimir force?

The Casimir force is based on the zero point energy. Physics does not categorically say that it is impossible to usefully extract energy from this source. However the work required to set up configurations that do so seems to exceed the energy recovered. This has not slowed an army of crackpots who claim to have found some way of doing so.

That said, a one-use battery is possible to build, but the effort required is far more than a chemical battery, and the energy densities are so much less, that building one seems entirely useless.

No, and the smallness of the force has nothing to do with it. While it's true that there's a force between two metal objects that you could use to do some work, this doesn't get you energy for free because you had to do some work yourself in order to pull them apart in the first place.

Consider that gravity is "weak". Is it not possible that the mechanics of casimir force, which cause two objects to be pushed together from the outside, might mimic gravity which appears to be two objects attracting?

Might it be that we can't find "gravity" as an attractive force, because it is casimir forces, as repulsive forces, over several scales?

But you can use things like tidal forces to do the work 'resetting' a system.

And? Tidal forces are just an energy source like any other. This is a bit like saying you could use a gasoline powered engine to do the work.

Yes, except that tidal forces are "renewable" in the sense that the energy comes from outside our eco-system. Thus if one is using such a method to "reset" the system the energy moved in to the local system is effectively free. Such energy acquired does not need an equal amount of work [from the local system] to drive as is moved in to the system.

That's the and. In short, in the same way solar energy brings energy in to the locality such a system could theoretically work thus being so down on it (as to say it will never be made to work) seems counter-logical.

So skip the complicated casimir effect energy generator and just use tidal forces or solar energy or what-have-you directly, that's the point I'm making.

No; absent any other problems, it's a tiny effect. And https://en.wikipedia.org/wiki/Casimir_Effect#Applications

Actually, there are some ideas about creating configurations in which the Casimir force is reversed (ie the two objects repel). There are people trying to use both configurations to improve the efficiency of micro-mechanical devices.

Zero-point energy, the origins of the Casmir force "may" (and this is a big may) be one day used as a source of energy

(Definition of 'may' in this case. As likely as finding and communicating with Alien lifeforms)

But the Casmir force itself is unlikely (for "ZPF" levels of unlikely)

I'm a big believer in the universe as predicted by the Fermi Paradox, and that we'll only ever interact with "human-descended" intelligences.

My gut still says it's more likely we'll talk to aliens than harvest vacuum energy. Entropy says we don't get anything for nothing. (I Am Not A Theoretical Physicist, though - or a xenobiologist, for that matter.)

That's an unfortunate attitude. He's not claiming "something for nothing," he's saying that zero-point energy (which demonstrably exists) could one day be harvested. It's very difficult, but not unimaginable.

I'm sure people said the same thing about nuclear energy until it was very, very clearly demonstrated.

It has very little to do with aliens, however.

The aliens bit was continuing the GP's probability comparison, nothing more.

That's a fallacious comparison: E = mc^2, the discovery of the neutron, and the discovery of uranium's fissile nature told us very clearly how to get nuclear energy (getting nuclear energy _controllably_, however...). Special relativity told us exactly how much power was available. Solid physics.

With ZPE extraction, the physics doesn't give us any way of accessing the energy beyond the Casimir effect, which is pretty restricted. Actually powering anything is in the realms of perpetual motion machines; wikipedia discusses it better than I can here: https://en.wikipedia.org/wiki/Zero-point_energy#Free-energy_...

(Edit: Rutherford did say the idea of nuclear energy was "hogwash", so you're right there...)

Non-human aliens, like apes? Dolphins? We've already seen non-human intelligences, in our own back yard. Not a great leap to imagine them elsewhere.

Ok, where I say 'alien', imagine I said 'extra-terrestrial'.

We know the probability of the universe evolving intelligent life from scratch is 1. We know nothing about the probability of the universe evolving intelligent life from scratch twice, and the Fermi paradox implies we're very unlikely to ever find out more.

Disagree. No reason to dismiss multiple intelligent lifeforms on one planet as not 'from scratch'.

The operative word is 'intelligent'. Probability of life is unknown; but that's not the issue presented.

No. The Casimir force is a consequence of the fact that the lowest energy state of a field is not zero. However, because it is the lowest energy state, by definition you cannot extract any energy from it.

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