2 slit experiment with fullerene

[amaterasu]

<div id="yiv1817897294"><div>http://hexagon.physics.wisc.edu/teaching/2007f_ph448/interes<span>ting%20pa</span>pers/zeilinger%20large%20molecule%20interference%20ajp%202003.pdf<br /><br /></div><div>this experiment makes me wonder if it is possible at all to fix the boundary between quantum and classical domains.</div><div>nanotechnology seems to deal with 'things' that reside or rather wander across the boundary between the small and average things, so to speak?<br /><br /></div><div>would it be that fullerene behaves&nbsp;like a quantum particle when cold but like a normal thing when hot?</div><div>in order to be a quantum thing, it must keep eluding (uncertainty and wave nature) and it is, of course, convenient when it's small (for obvious reason) and when it's cold so it won't emit heat (information)&nbsp;and get caught by an <span class="wordlink">infrared</span> <span class="wordlink">camera, for instance</span>.<br /><br /></div><div>come to think of it, because of this same quantum uncertainty,&nbsp;things would not become flattened.&nbsp; in other words&nbsp;atoms won't become squashed -&nbsp;thanks to the wobbly state of&nbsp;their mass.&nbsp; meaning uncertainty can't become '0' by definition since '0' is pretty firm state.<br /><br /></div><div>perhaps there's no such thing as a rigid body after all.&nbsp; how weird...&nbsp;<br /><br />&nbsp;</div></div> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://hexagon.physics.wisc.edu/teaching/2007f_ph448/interesting%20papers/zeilinger%20large%20molecule%20interference%20ajp%202003.pdfthis experiment makes me wonder if it is possible at all to fix the boundary between quantum and classical domains.nanotechnology seems to deal with 'things' that reside or rather wander across the boundary between the small and average things, so to speak?would it be that fullerene behaves&nbsp;like a quantum particle when cold but like a normal thing when hot?in order to be a quantum thing, it must keep eluding (uncertainty and wave nature) and it is, of course, convenient when it's small (for obvious reason) and when it's cold so it won't emit heat (information)&nbsp;and get caught by an infrared camera, for instance.come to think of it, because of this same quantum uncertainty,&nbsp;things would not become flattened.&nbsp; in other words&nbsp;atoms won't become squashed -&nbsp;thanks to the wobbly state of&nbsp;their mass.&nbsp; meaning uncertainty can't become '0' by definition since '0' is pretty firm state.perhaps there's no such thing as a rigid body after all.&nbsp; how weird...&nbsp;&nbsp; <br />Posted by amaterasu</DIV></p><p>There is no "boundary" between the quantum and the classical.&nbsp; Quantum mechanics is not limited to the very small, just as general relativity is not limited to the very large.&nbsp; Quantum mechanics reduces to classical mechanics in the limit as masses become large, but it always applies.&nbsp; It is just that the effects are not so noticeable with large bodies, uncertainties in position and momentum are very small relative to the expected values, so the classical approximation is accurate, but quantum mechanics is more accurate.</p><p>What do you mean by the idea that atoms may nor may not "become squished"?&nbsp;</p><p>There is no such thing as a rigid body in the sense that the term is used in idealized mechanical models.&nbsp; That in fact is a consequence of special relativity -- a rigid body would provide a medium for instantaneous transmission of signals over distance.&nbsp; It also is a consequence of quantum mechanics in the form of the the electromagnetic forces between atoms and molecules that results in solid materials being elastic in nature, and not perfectly rigid.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[amaterasu]

<p>thank you for the reply, Dr&nbsp; <br /><br /><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>There is no "boundary" between the quantum and the classical.&nbsp; Quantum mechanics is not limited to the very small, just as general relativity is not limited to the very large.&nbsp; Quantum mechanics reduces to classical mechanics in the limit as masses become large, but it always applies.&nbsp; It is just that the effects are not so noticeable with large bodies, uncertainties in position and momentum are very small relative to the expected values, so the classical approximation is accurate, but quantum mechanics is more accurate.</DIV><br />actually,&nbsp;by&nbsp;'classical domain', i was referring to our everyday things rather than the very large.<br />i think i see your point, though.&nbsp; i tend to see Newtonian mechanics and Maxwell's electromagnetic theory as approximation to both Einstein's gravitation theory and quantum mechanics.<br />&nbsp;<br /><br />Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>What do you mean by the idea that atoms may nor may not "become squished"?&nbsp;There is no such thing as a rigid body in the sense that the term is used in idealized mechanical models.&nbsp; That in fact is a consequence of special relativity -- a rigid body would provide a medium for instantaneous transmission of signals over distance.&nbsp; It also is a consequence of quantum mechanics in the form of the the electromagnetic forces between atoms and molecules that results in solid materials being elastic in nature, and not perfectly rigid. <br />Posted by DrRocket</DIV><br />http://books.google.co.jp/books?id=GC0vc22hlxEC&pg=PA63&lpg=PA63&dq=resistance+to%E3%80%80atomic+compression&source=web&ots=xuN1tArR4B&sig=dSsE64XlljKmSFZAO9pZ6hAv6qw&hl=en&sa=X&oi=book_result&resnum=5&ct=result<br /><br />i mean the 'resistance to atomic compression' being a quantum mechanical effect - rather than a classical one.<br />i still feel quite baffled by the notion though.</p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>thank you for the reply, Dr&nbsp; actually,&nbsp;by&nbsp;'classical domain', i was referring to our everyday things rather than the very large.i think i see your point, though.&nbsp; i tend to see Newtonian mechanics and Maxwell's electromagnetic theory as approximation to both Einstein's gravitation theory and quantum mechanics.&nbsp;http://books.google.co.jp/books?id=GC0vc22hlxEC&pg=PA63&lpg=PA63&dq=resistance+to%E3%80%80atomic+compression&source=web&ots=xuN1tArR4B&sig=dSsE64XlljKmSFZAO9pZ6hAv6qw&hl=en&sa=X&oi=book_result&resnum=5&ct=resulti mean the 'resistance to atomic compression' being a quantum mechanical effect - rather than a classical one.i still feel quite baffled by the notion though. <br />Posted by amaterasu</DIV></p><p>"Very large" can mean lots of things depending on the context.&nbsp; With respect to quantum mechanics, very large means macroscopic -- a baseball is very large compared to an atom.&nbsp; So everyday things are very large from a quantum mechanical perspective.&nbsp; That is why the uncertainty in the position of a baseball is not important to either the pitcher or the batter, it is very small by everyday standards.</p><p>Newton's mechanics and Maxwell's electromagnetism are approximations to quantum mechanics, in particular to quantum electrodynamics and they suffice for macroscopic considerations.&nbsp; &nbsp;Newton's mechanics is also an approximation to special and general relativity, and applies when speeds are low relative to light and in low to moderate gravitational fields.&nbsp; Maxwell's electromagnetism in compatible with and actually suggested special relativity. So the way you look at Newtonian mechanics and classical electrodynamics is&nbsp;quite proper.&nbsp; In fact&nbsp;that perspective is representative of the correspondence principle which is very important in understanding the nature of physical&nbsp;theories. &nbsp;</p><p>I think the passage you are looking at in that book is the quote from Feynman "So now we understand why we do not fall through the floor ...the resistance to atomic compression is a quantum-mechanical effect and not a classical effect."&nbsp; This quote comes from <em>The Feynman Lectures on Physics</em> volume 3 page 2-6.&nbsp; What Feynman is talking about is why atoms resist&nbsp;forces that might tend to make the electron closer to the nucleus, and in fact why the&nbsp;negatively charged electron is not drawn into the positively charged nucleus.&nbsp; What he is saying is that to do so would confine the electron to a smaller volume and following the uncertainty principle that would require higher momentum and energy and energy on the average.</p><p>BTW I highly recommend Feynman's book, a 3-volume set that contains the lectures that he gave to a freshman physics class at Cal Tech in the early 1960s.&nbsp; If you want to understand quantum mechanics, Feynman's perspective will be invaluable.&nbsp; He probably understood quantum mechanics as well or better than anyone who has ever walked the planet and his "freshman lectures" are masterful. Quantum mechanics is the subject of volume 3.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[amaterasu]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think the passage you are looking at in that book is the quote from Feynman "So now we understand why we do not fall through the floor ...the resistance to atomic compression is a quantum-mechanical effect and not a classical effect."&nbsp; This quote comes from The Feynman Lectures on Physics volume 3 page 2-6.&nbsp; <strong>What Feynman is talking about is why atoms resist&nbsp;forces that might tend to make the electron closer to the nucleus, and in fact why the&nbsp;negatively charged electron is not drawn into the positively charged nucleus.&nbsp; What he is saying is that to do so would confine the electron to a smaller volume and following the uncertainty principle that would require higher momentum and energy and energy on the average.</strong>BTW I highly recommend Feynman's book, a 3-volume set that contains the lectures that he gave to a freshman physics class at Cal Tech in the early 1960s.&nbsp; If you want to understand quantum mechanics, Feynman's perspective will be invaluable.&nbsp; He probably understood quantum mechanics as well or better than anyone who has ever walked the planet and his "freshman lectures" are masterful. Quantum mechanics is the subject of volume 3. <br />Posted by DrRocket</DIV><br />cheers Dr, for your brilliant explanation.<br /><br />as for the Feynman's Lectures on Physics - yes, they should definitely deserve a place on the bookshelf of&nbsp;anyone in the biology field&nbsp; ;-)&nbsp; seriously though,&nbsp;i've been meaning to read them for moons.&nbsp; thanks for reminding me of it.<br /> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>cheers Dr, for your brilliant explanation.as for the Feynman's Lectures on Physics - yes, they should definitely deserve a place on the bookshelf of&nbsp;anyone in the biology field&nbsp; ;-)&nbsp; seriously though,&nbsp;i've been meaning to read them for moons.&nbsp; thanks for reminding me of it. <br />Posted by amaterasu</DIV></p><p>It is not my brilliant explanation. It is Feynman's.&nbsp; He has lots of them.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[jbachmurski]

<span><p>I&rsquo;ve got a question about the two slit experiment. Is it done in a vacuum? If not, I wouldn&rsquo;t think it would be accurate.</p></span>

 

[origin]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I&rsquo;ve got a question about the two slit experiment. Is it done in a vacuum? If not, I wouldn&rsquo;t think it would be accurate. <br />Posted by jbachmurski</DIV><br /><br />Why not? <div class="Discussion_UserSignature"> </div>

 

[amaterasu]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I&rsquo;ve got a question about the two slit experiment. Is it done in a vacuum? If not, I wouldn&rsquo;t think it would be accurate. <br />Posted by jbachmurski</DIV></p><p>i am far from an expert on this, but... i guess yes, as indicated in "C. The detector" of the paper, in order to observe quantum interference incl&nbsp;of larger objects such as fullerenes,&nbsp;experiments need to be done under a high vacuum - most probably&nbsp;3*10^-10 mbar&nbsp;or below.&nbsp; no?<br /><br /></p> <div class="Discussion_UserSignature"> </div>