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This might seem a silly question, but here it goes:

Of all possible values for a measure of distance, which is the smallest that makes sense talking about?

I mean, I could talk about $10^{-100000}$ meters but in real life this value is smaller than anything we know (i think), so it wouldn't make any sense talking about this value, now would it? Initially I thought about Planck length, but I'm not sure.

Please not I'm not referring to mathematics, any number can be of use in mathematics. But in real life, small values like $10^{-100000}$ meters don't make sense.

So, what is smallest distance value that makes sense talking about?


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marked as duplicate by Brandon Enright, John Rennie, Qmechanic Mar 12 '14 at 10:23

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Possible duplicates: and links therein. – Qmechanic Feb 6 '14 at 22:27
up vote 3 down vote accepted

According to the generalized uncertainty principle, the Planck length is, in principle, within a factor of order unity, the shortest measurable length – and no improvement in measurement instruments could change that. (Wikipedia)

$$1 \text{ Planck length} = 1.61619926 \times {10}^{-35} m$$

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Thanks. I should have checked that. – Dayman75 Feb 6 '14 at 23:16
You should note that this is speculative and only holds true for certain physical theories (which remain untested) beyond the standard model. It's better to say that the Planck length is the smallest distance for which our current theories should hold. Physics at scales less than the Planck length is not currently known. – mcFreid Feb 7 '14 at 13:18

As an engineer I would say $10^{-5}\mathrm{m}$ because for mechanical purposes the smoothest surface finishing does not need to be net as this. As a practical chemist I would say $10^{-10}\mathrm{m}$ is small enough since I will never care about the very real diameter of an electron. I guess physicist would like to get a little bit smaller. Basically speaking, there is, at least, some interesting and energetic Electro Magentic wave with smaller wavelengths ...

But you are not expecting a definitive answer to that kind of question, do you ?

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You're right. It's hard to get a definitive answer. I was just searching if there was any field of study which might use smaller values than Planck Length. But thanks for your answer. – Dayman75 Feb 6 '14 at 23:20
You're welcome, it is not the perfect answer, just a pragmatic point of view. – jlandercy Feb 6 '14 at 23:26
It has been over a decade, but last I looked into it the experiments to determine the size of the electron had all delivered an answer equal to zero within experimental error (which was really really small compared to 10e-10m. So, I lean more towards the Planck length. I'll try to find the relevant papers tomorrow. – Jon Custer Mar 12 '14 at 0:30

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