How tiny are protons?

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Offline Eric A. Taylor

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How tiny are protons?
« on: 14/07/2010 20:45:00 »
In the news part of the program Ben spoke about the proton being smaller than thought before. I thought a proton was a point particle and had no size at all?
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Offline lightarrow

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How tiny are protons?
« Reply #1 on: 15/07/2010 19:58:53 »
In the news part of the program Ben spoke about the proton being smaller than thought before. I thought a proton was a point particle and had no size at all?
No, no, the proton cannot be point-like because it's not an elementary particle, it's made of 2 up quarks and 1 down quark.

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Offline chris

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How tiny are protons?
« Reply #2 on: 15/07/2010 20:01:41 »
The diameter of a proton, as near as dammit, is 1 femtometre (10^-15m).

Chris
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Offline Eric A. Taylor

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How tiny are protons?
« Reply #3 on: 17/07/2010 08:17:35 »
From what I understand about quantum theory, at some point "size" begins to lose it's meaning. At what size does this happen.
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Offline lightarrow

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How tiny are protons?
« Reply #4 on: 17/07/2010 15:15:04 »
From what I understand about quantum theory, at some point "size" begins to lose it's meaning. At what size does this happen.
1. Above Planck's lenght, an object's size starts losing meaning at dimensions less than the coherence lenght of the wavepacket describing the object.
2. Under Planck's lenght, size doesn't exist anylonger.

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Offline tangoblue

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How tiny are protons?
« Reply #5 on: 21/07/2010 23:36:44 »
About this size:


see it, just above this line...If you squint your eyes you might see it...no... oh well.