# Uncertainty Principle tricked - so why not Newtonian Determinism?

Recently I read that some results are obtained in directions of tricking the uncertainty principle. The relevant link is here: http://www.caltech.edu/content/tricking-uncertainty-principle , and the paper is on the Arxiv.

Now the problem I have is that if we can trick the uncertainty principle, doesn't this mean that the uncertainty principle is just a restriction on our current ability to make measurements rather than a fundamental limitation?

If so, can we assert that actually the universe does have certain physical knowledge of each particle's momentum and position simultaneously, and the interaction of the rest of the universe with that particle is not uncertain. But isn't this simply Newtonian Determinism?

So were is the catch?

• @Dvij: You should really improve the readability of your post and make it more obvious what it is you are asking. Meanwhile, Newtonian determinism is dead since the are no local hidden variables Jun 30, 2014 at 11:23
• I'm not a big fan of downvoting at the best of times, and downvoting because someone's English is poor seems to me especially venomous. A more honourable approach would be to edit Dvij's question to improve the grammar. Jun 30, 2014 at 11:26
• Dvij, I've attempted to improve your question without doing too much violence to it. If you don't like the edit please feel free to roll it back. Jun 30, 2014 at 11:41
• @JohnRennie I am really hoping the same behavior in the case of some GR questions. ( meta.physics.stackexchange.com/questions/5868/… ) Jun 30, 2014 at 11:42
• A good search term is squeezed light; exactly this approach is used to wring more phase sensitivity out of the resonant interferometry used in LIGO / LISA / Einstein telescope gravitational wave detection. As in John's answer, it's simply getting increased sensitivity to one conjugate observable at the expense of the other: all in accordance with the HUP. See also Squeezed Coherent State Wiki Jun 30, 2014 at 13:47

This is a partial answer based on a quick read of the paper. If somebody would like to post a fuller analysis I'll delete this.

Anyhow, the experiment is not defying the uncertainty principle. Instead it's effectively moving the uncertainty around. The uncertainty attached to the whole system is unchanged, but it's possible to measure one aspect of the motion more accurately that the UP allows at the cost of making measurements of other aspects of the system less accurate than the UP allows.

However this is a somewhat limited approach and only allows you to beat the UP by a small amount. It certainly doesn't amount to Newtonian determinism.

• A good search term for the OP (based on your answer) would then be squeezed light; exactly this approach is used to wring more phase sensitivity out of the resonant interferometry used in LIGO / LISA / Einstein telescope gravitational wave detection Jun 30, 2014 at 13:43
• @WetSavannaAnimalakaRodVance: ah yes, good point. It would be worth you expanding that into an answer. Jun 30, 2014 at 15:54
• Beating the UP even by a small amount doesn't mean that it is not a fundamental rule? And if our technology can beat the UP by a small amount today then we can beat it by a larger amount also in future.
– ACat
Jul 1, 2014 at 3:15
• @Dvij Just to clarify: the experiment does not demonstrate a HUP violation (in fact, it rather nicely showcases the principle). The experiment just shows that you can measure the position quite precisely if you're ok with a large momentum uncertainty. The merit is in beating a separate limit (called the Standard Quantum Limit) which is technical and not fundamental in nature. The press release you linked to is rather misleading, but it's job is to drum up hype for the paper and it needs to be read in that light. Jun 30, 2017 at 20:14
• @EmilioPisanty Yes, I do realize that now. I was actually just editing some of my old questions for grammar etc. but didn't realize they would bring them in the active list.
– ACat
Jun 30, 2017 at 20:42