# Absolute zero and beyond

**URL:** https://boards.straightdope.com/t/absolute-zero-and-beyond/635070
**Category:** Cecil's Columns/Staff Reports
**Created:** [September 18, 2012, 2:47pm UTC](https://boards.straightdope.com/t/absolute-zero-and-beyond/635070 "2012-09-18T14:47:18Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![Dult](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@Dult](https://boards.straightdope.com/u/Dult)
#### Post date: [September 18, 2012, 2:47pm UTC](https://boards.straightdope.com/t/absolute-zero-and-beyond/635070/1 "2012-09-18T14:47:18Z")

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So if movement virtually stops at absolute zero, when does it really stop?

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### Author: ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)
#### Post date: [September 18, 2012, 6:28pm UTC](https://boards.straightdope.com/t/absolute-zero-and-beyond/635070/2 "2012-09-18T18:28:55Z")

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By definition, when molecules actually stop moving is absolute zero. However, it is difficult to get to absolute zero because quantum effects keep things destabilized.

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### Author: ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)
#### Post date: [September 18, 2012, 6:36pm UTC](https://boards.straightdope.com/t/absolute-zero-and-beyond/635070/3 "2012-09-18T18:36:12Z")

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> [@Dult](#):
>
> So if movement virtually stops at absolute zero, when does it really stop?

It can’t. Quantum mechanics and the uncertainty principle. If something wasn’t moving at all it’s uncertainty of momentum is zero which means it’s uncertainty of position is infinite. It’s like everywhere, man!

Throw in the effects of particles popping into and out of existence due to the unavoidable quantum vacuum state, etc., and nothing can ever really be stopped.

[Zero-point energy](http://en.wikipedia.org/wiki/Zero-point_energy) can be such a bother. It even prevents Helium from freezing (at normal pressure).

So absolute zero is best defined based on Thermodynamic principles such as minimum entropy. Thermo only applies to the statistical properties of lots of particles. It doesn’t describe the behavior of a single particle.

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### Author: ![Old\_Red](https://avatars.discourse-cdn.com/v4/letter/o/7feea3/32.png) [@Old\_Red](https://boards.straightdope.com/u/Old_Red)
#### Post date: [September 18, 2012, 9:07pm UTC](https://boards.straightdope.com/t/absolute-zero-and-beyond/635070/4 "2012-09-18T21:07:00Z")

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It’s when it is so cold, your nuts fall off.