Because there is never more than one photon "in flight" at any given 
time.  Even at 1 photon/s, we still eventually get spots.

Atoms also don't emit synchrotron radiation, despite there being charged 
particles accelerating around their little "orbits" in there.

But yes, in 1913, people were still hoping there was another explanation 
for these two observations, other than that pesky quantum theory.  It 
was in 1915 that Debye made the key observation that collapsed 
determinism as we knew it.  I don't think he was very happy about that.  
Neither was Einstein.

-James Holton
MAD Scientist

On 4/19/2013 9:43 AM, Tim Gruene wrote:
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> Hello Bernhard,
>
> could you explain this? A photon is the exchange particle of the
> electromagnetic force, i.e. as soon as you have more than two charged
> particles interacting there is more than one photon - why is it
> incorrect to use the term "multi-photon process" in the context of
> X-ray diffraction?
>
> Cheers,
> Tim
>
> On 04/19/2013 06:19 PM, Bernhard Rupp (Hofkristallrat a.D.) wrote:
>> However, a reviewer could reject the method on theoretical grounds
>> - the explanation of X-ray diffraction as a multi-photon process is
>> not correct....
>>
>> BR
>>
>> -----Original Message----- From: CCP4 bulletin board
>> [mailto:[log in to unmask]] On Behalf Of Peter Artymiuk Sent:
>> Friday, April 19, 2013 7:11 AM To: [log in to unmask] Subject:
>> Re: [ccp4bb] popular piece on X-ray crystallography
>>
>> Just to clarify, Jeremy was not being serious, but imagining what
>> an awkward / obnoxious grant reviewer might have said in 1913. But
>> your points would be valuable in rebutting such a view
>>
>> Pete
>>
>>
>>
>> On 19 Apr 2013, at 11:28, Navdeep Sidhu wrote:
>>
>>> Dear Pet,
>>>
>>> On the contrary, far as I know, nature seems to require most
>>> solids we see around us to be crystalline. And much of the rest
>>> is either gaseous or plasma. Hence, by the reasoning proposed, we
>>> are led to suspect a different conclusion: that it's studies
>>> dealing with the remaining state that have "little general
>>> applicability as the requirement for objects to force themselves
>>> into" the disordered arrays of the liquid state "is an absurd
>>> limitation." (However, I'd support funding it nevertheless.)
>>>
>>> Best regards, Navdeep
>>>
>>>
>>> --- On Fri, Apr 19, 2013 at 10:14:04AM +0100, Peter Artymiuk
>>> wrote:
>>>> Another of my colleagues, Jeremy Craven, is an NMR
>>>> spectroscopist and
>> bioinformatician. He is in referee mode at present and comments:
>>>>
>>>>> From: Jeremy Craven <[log in to unmask]> Date: 19
>>>>> April 2013 10:05:18 GMT+01:00 To: Peter Artymiuk
>>>>> <[log in to unmask]> Subject: Re: Fwd: popular piece
>>>>> on X-ray crystallography
>>>>>
>>>>> I suspect this technique will have little general
>>>>> applicability as the
>> requirement for objects to force themselves into ordered arrays is
>> an absurd limitation. I would not support funding it.
>>>>> Jeremy
>>>>
>>>> I fear he may be right
>>>>
>>>> best wishes Pet
>>>>
>>>>
>>>>
>>>>
>>>> On 19 Apr 2013, at 09:53, David Briggs wrote:
>>>>
>>>>> Following on from that - readers may be interested in Stephen
>>>>>   Curry's post in the Guardian, regarding the Crystallography
>>>>> exhibit at the London Science Museum.
>>>>>
>>>>> http://www.guardian.co.uk/science/occams-corner/2013/apr/19/1
>>>>>
>>>>>
>>>>>
> regards,
>>>>> Dave
>>>>>
>>>>> ============================ David C. Briggs PhD
>>>>> http://about.me/david_briggs
>>>>>
>>>>>
>>>>> On 19 April 2013 09:44, Peter Artymiuk
>>>>> <[log in to unmask]>
>> wrote:
>>>>>> Dear all
>>>>>>
>>>>>> In Britain there is a free newspaper that you can pick up
>>>>>> on buses
>> called the Metro. My colleague Geoff Ford pointed out this short
>> feature on the history X-ray crystallography in last Monday's Metro
>> newspaper. I think it's rather good.
>>>>>> http://www.cosmonline.co.uk/blog/2013/04/14/conquering-realm-invisi
>>>>>>
>>>>>>
> ble
>>>>>> best wishes Pete
>>>>>>
>>>>>>
>>>>>>
>>>>>> Prof Peter Artymiuk Krebs Institute Department of Molecular
>>>>>> Biology & Biotechnology University of Sheffield Sheffield
>>>>>> S10 2TN ENGLAND
>>>
>>> --- Navdeep Sidhu Departments of Structural Chemistry &
>>> Pediatrics II University of Goettingen Office Address: Institute
>>> of Inorganic Chemistry Tammannstrasse 4 37077 Goettingen Germany
>>> Email: [log in to unmask] Phone: +49 551 39 33059 Fax:
>>> +49 551 39 22582 Dept. Homepage: http://shelx.uni-ac.gwdg.de/
>>> ---
>> Prof Peter Artymiuk Krebs Institute Department of Molecular Biology
>> & Biotechnology University of Sheffield Sheffield S10 2TN ENGLAND
>>
> - -- 
> - --
> Dr Tim Gruene
> Institut fuer anorganische Chemie
> Tammannstr. 4
> D-37077 Goettingen
>
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