The smallest particle?

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LacheLimbo

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<p>It's easier for me to comprehend the vastness of space outward than the depth of space inward.</p><p>What is the smallest known particle? How much smaller does current theory predict?</p><p>I visualize a fracal animation where as you zoom into an edge you&nbsp;see there are just more fractal edges and so on and so on. Is there infinite depth?</p>
 
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baulten

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<p>As far as I understand it, all elementary particles, to us, behave as zero-dimensional particles, meaning they have no depth, width, or height.</p><p>I'm not sure on this, though.&nbsp;</p>
 
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centsworth_II

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<font color="#666699"><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>...all elementary particles, to us, behave as zero-dimensional particles...<br /> Posted by baulten</DIV><br /></font>Or, if you go with string theory, particles are one-dimensional strings or loops.&nbsp; But elementary particles, if they have any size at all, are too small to measure the size of.&nbsp; All sizes at that level are theoretical. <div class="Discussion_UserSignature"> </div>
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It's easier for me to comprehend the vastness of space outward than the depth of space inward.What is the smallest known particle? How much smaller does current theory predict?I visualize a fracal animation where as you zoom into an edge you&nbsp;see there are just more fractal edges and so on and so on. Is there infinite depth? <br /> Posted by LacheLimbo</DIV></p><p>It depends on what you are defining as 'size'.&nbsp; In particle physics, size means mass.&nbsp; In that case any particle with zero mass would be the smallest (i.e. photons, gluons).&nbsp; The smallest particle that I can think of that actually has mass would be a certain flavor of neutrino.</p><p>Then there are elementary particles which can not be broken further down into smaller particles, but these can have varying masses.&nbsp;</p><p>And, as far as I know, there is no way to quantify a physical size of these particles.&nbsp; Such determining surface area or volume is beyond our capabilities.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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nnunn

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It's easier for me to comprehend the vastness of space outward than the depth of space inward.What is the smallest known particle? How much smaller does current theory predict?I visualize a fractal animation where as you zoom into an edge you&nbsp;see there are just more fractal edges and so on and so on. Is there infinite depth? <br />Posted by LacheLimbo</DIV><br /><br />A&nbsp;fresh approach this dusty and crusty problem: imagine the fundamental material particle is that primitive&nbsp;object which first curves&nbsp;some n-dimensional manifold of space.&nbsp; If these were then to huddle and combine to form the standard model's leptoquarks (stringy loops of triads of preons?), their ability to curve space would (in various ways?) appear in their composite leptonic and quarkish structures.&nbsp; Such a theory naturally accommodates a kind of GR model of gravity.&nbsp; </p><p>If we then also allow for some linear "Maxwellian" interaction between the structures, we get something more Newtonian. (Remember how Kaluza tried adding that fifth row and column to one of Einstein's tensors...)</p><p>So if there are both linear and non-linear components to the gravitational interaction, could this help explain why neither Einstein's nor Newton's theory have proved fully satisfactory alone.</p><p>We may still need to join some dots?</p>
 
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kg

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Is there any limit as to how large or how small a wavelength of light can be?&nbsp; Or maybe I should ask how little or how much energy a photon can have?
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Is there any limit as to how large or how small a wavelength of light can be?&nbsp; Or maybe I should ask how little or how much energy a photon can have? <br /> Posted by kg</DIV></p><p>The wavelength (frequency) and energy of a photon are directly related.&nbsp; The shorter the wavelength, the higher the frequency and thus the more energy.</p><p>I'm not sure, but i don't believe there is any theoretical limit to this.&nbsp; The only physical limits I can think of would be wavelengths at the scale of the Planck length for gamma rays and the size of the universe for radiowaves, but detecting such waves might prove to be impossible.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The wavelength (frequency) and energy of a photon are directly related.&nbsp; The shorter the wavelength, the higher the frequency and thus the more energy.I'm not sure, but i don't believe there is any theoretical limit to this.&nbsp; The only physical limits I can think of would be wavelengths at the scale of the Planck length for gamma rays and the size of the universe for radiowaves, but detecting such waves might prove to be impossible.&nbsp; <br />Posted by derekmcd</DIV><br />&nbsp;</p><p>I guess you might use the equations E=mc^2 and E-h*nu to conclude that the maximum frequency would be </p><p>nu = M*C^2/h </p><p>where M is the total mass/energy of the universe.&nbsp; That ought to be a really high frequency.&nbsp; There might be a problem or three in actually producing a photon with this much energy, but it would be an upper bound on energy and hence frequency.&nbsp; Calculating that upper bound might be a problem as we don't know the value of M.</p><p>With regard to the original question of size of particles, I think the real answer is that we don't know.&nbsp; Most particles are currently modeled as point particles, but there are problems with the model.&nbsp; It seems that there are contradictions if you model the particle as a point, and contradictions if you don't.&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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baulten

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<p>"With regard to the original question of size of particles, I think the real answer is that we don't know.&nbsp; Most particles are currently modeled as point particles, but there are problems with the model.&nbsp; It seems that there are contradictions if you model the particle as a point, and contradictions if you don't. "</p><p>This is what I meant.&nbsp; They do have varying masses, though, but to us, they look like points.&nbsp; We can't possibly give them a size or shape because of our current limitations.&nbsp; They may be 1, 2, or 10823471984 dimensional objects, but right now we just don't have the ability to tell for sure. </p>
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I guess you might use the equations E=mc^2 and E-h*nu to conclude that the maximum frequency would be nu = M*C^2/h where M is the total mass/energy of the universe.&nbsp; That ought to be a really high frequency.&nbsp; There might be a problem or three in actually producing a photon with this much energy, but it would be an upper bound on energy and hence frequency.&nbsp; Calculating that upper bound might be a problem as we don't know the value of M.</p><p>Posted by DrRocket</DIV></p><p>&nbsp;</p><p>I suppose if viewed as a particle, the upper bound of the frequency would only be limited by the mass/energy of the universe.&nbsp; That, by itself, makes sense.&nbsp; However, given that the photon can also be view as a wave (being inversely proportional to the frequency), the limiting factor would be a wavelength as small as the Planck length.&nbsp; You're stuck with a limited number of oscillations per second (frequency) or else the wave would be propogating faster than C. </p><p>Whether that would exceed the total mass/energy of the universe, I don't know.&nbsp; I doubt it, but I don't care to try to figure it out to prove it.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /></p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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kg

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<p>&nbsp; The only physical limits I can think of would be wavelengths at the scale of the Planck length for gamma rays and the size of the universe for radiowaves,&nbsp;</p><p>In that case is it possible for the wavelength of a photon to&nbsp;be long enough to be lengthening faster than the speed of light due the the expansion of the universe?&nbsp;&nbsp;</p>
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In that case is it possible for the wavelength of a photon to&nbsp;be long enough to be lengthening faster than the speed of light due the the expansion of the universe?&nbsp;&nbsp; <br /> Posted by kg</DIV></p><p>You are referring to the <strong>Cosmological Redshift</strong>.&nbsp; The photon still travels at C (having zero rest mass, it has no choice), however the wavelength is physically increased (frequency decreased or redshifted in the electromagnetic spectrum) by the expansion of space.&nbsp; Anytime the wavelength is increased, the frequency MUST decrease... they are inversely proportional to each other.</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I suppose if viewed as a particle, the upper bound of the frequency would only be limited by the mass/energy of the universe.&nbsp; That, by itself, makes sense.&nbsp; However, given that the photon can also be view as a wave (being inversely proportional to the frequency), the limiting factor would be a wavelength as small as the Planck length.&nbsp; You're stuck with a limited number of oscillations per second (frequency) or else the wave would be propogating faster than C. Whether that would exceed the total mass/energy of the universe, I don't know.&nbsp; I doubt it, but I don't care to try to figure it out to prove it. <br />Posted by derekmcd</DIV></p><p>You lost me here.&nbsp; How is frequency related to speed?&nbsp; And how is the&nbsp;Planck length a limiting factor ?&nbsp; Are you supposing some sort of quantization of distance involving the Planck length ?&nbsp; If so, are you speculating, or is there some established theory on which you are relying ?<br /></p> <div class="Discussion_UserSignature"> </div>
 
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derekmcd

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<p>Let me first state that I am at my own threshhold of understanding and the questions you are asking are probably going to make me sound completely incoherent. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /> </p><p><strong>How is frequency related to speed?&nbsp;</strong></p><p>It's not directly related to speed because you can't increase the frequency without shortening the wavelength.&nbsp; Since f=v/nu, when concidering a photon, if you increase the frequency without decreasing the wavelength, it will propogate at speeds faster than C. </p><p><strong>And how is the&nbsp;Planck length a limiting factor?</strong>&nbsp;</p><p>I understand it might be a rather arbitrary length, but isn't the Planck length limit of our physical understanding?&nbsp; I suppose It might have been better to say "IF" the Planck length is the limit.&nbsp; I'm sure in the quantum world, there's no limit, but everything becomes rather uncertain beyond this point.&nbsp; I'm not sure how to describe a wavelength any smaller and have it be useful.</p><p><strong>Are you supposing some sort of quantization of distance involving the Planck length?&nbsp; If so, are you speculating, or is there some established theory on which you are relying? </strong></p><p>I'm not sure if you can quantize distance or time, so... I guess you could say I'm speculating, but I'd rather say I'm just using the smallest useful metric that I can be reasonably certain of.</p><p>If Planck time is the how long it take for a photon to travel the distance of a Planck length, how could the wavelength be any shorter unless the frequency of oscillations are faster than Planck time?&nbsp; Are we even capable yet of thinking in shorter terms?&nbsp; I'm sure quantum theories of gravity or string theories can get us there, but I don't know.</p><p>Again, I'm at my limits here and google is only as smart as the person using it which in my case isn't saying much.&nbsp; If you catch me reciting a bunch of gibberish, I take no offense in being corrected.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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DrRocket

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<p>Let me first state that I am at my own threshhold of understanding and the questions you are asking are probably going to make me sound completely incoherent. </p><p><font color="#0000ff">I'm pretty&nbsp;much there myself.</font>&nbsp;</p><p>How is frequency related to speed?&nbsp;It's not directly related to speed because you can't increase the frequency without shortening the wavelength.&nbsp; Since f=v/nu, when concidering a photon, if you increase the frequency without decreasing the wavelength, it will propogate at speeds faster than C.</p><p><font color="#0000ff">In your equation here f is wavelength and nu is frequency (or vice versa, since the equation would be the same).&nbsp; The main thing is that for light v=c and c is constant in a vacuum so that you can't change frequency without changing wavelength.&nbsp; I would normally use lambda in place of f, but they are just symbols and any symbol will do.</font></p><p>&nbsp;And how is the&nbsp;Planck length a limiting factor?&nbsp;I understand it might be a rather arbitrary length, but isn't the Planck length limit of our physical understanding?&nbsp; I suppose It might have been better to say "IF" the Planck length is the limit.&nbsp; I'm sure in the quantum world, there's no limit, but everything becomes rather uncertain beyond this point.&nbsp;</p><p><font color="#0000ff">I have seen a description of the Planck length, but never a useable model based on it.&nbsp; Perhaps there is something in string theory, but string theory is not yet a useful physical theory.&nbsp; With current accepted&nbsp;models I am not aware of any limitation on length.&nbsp;&nbsp;But the Planck length is so small&nbsp;(considerably smaller than the diameter of a nucleus) that measuring anything on that&nbsp;scale ought to be, at best, rather difficult.&nbsp;&nbsp;So, I&nbsp;don't know if there any real limit imposed&nbsp;on wavelength at that scale, and I suspect that speculation on that issue is well beyond anything that our current models can&nbsp;be expected to handle and give accurate predictions.&nbsp;</font>&nbsp;</p><p>&nbsp;I'm not sure how to describe a wavelength any smaller and have it be useful.Are you supposing some sort of quantization of distance involving the Planck length?&nbsp; If so, are you speculating, or is there some established theory on which you are relying? I'm not sure if you can quantize distance or time, so... I guess you could say I'm speculating, but I'd rather say I'm just using the smallest useful metric that I can be reasonably certain of.If Planck time is the how long it take for a photon to travel the distance of a Planck length, how could the wavelength be any shorter unless the frequency of oscillations are faster than Planck time?&nbsp; Are we even capable yet of thinking in shorter terms?</p><p><font color="#0000ff">Sure you can think of shorter times and wavelengths.&nbsp; That is a property of the real numbers.&nbsp;&nbsp;Given any positive real number there is always a smaller positive real&nbsp;number -- just divide by 2 for instance.&nbsp; The real question is whether or not there is some sort of physical limitation that occurs at the Planck length.&nbsp; I dunno.&nbsp; I don't think current theory has such a limit, but we also know that current theory is not the final story.</font>&nbsp;</p><p>&nbsp; I'm sure quantum theories of gravity or string theories can get us there, but I don't know.Again, I'm at my limits here and google is only as smart as the person using it which in my case isn't saying much.&nbsp; If you catch me reciting a bunch of gibberish, I take no offense in being corrected.</p><p><font color="#0000ff">I don't think Google is going to help here, because I don't think anybody really knows.&nbsp; I don't think your idea is gibberish, but I don't think it is reflected in an established useful theory --- yet.</font></p><p><br />Posted by derekmcd[/QUOTE]<br /></p> <div class="Discussion_UserSignature"> </div>
 
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billslugg

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A&nbsp;fresh approach this dusty and crusty problem: imagine the fundamental material particle is that primitive&nbsp;object which first curves&nbsp;some n-dimensional manifold of space.&nbsp; If these were then to huddle and combine to form the standard model's leptoquarks (stringy loops of triads of preons?), their ability to curve space would (in various ways?) appear in their composite leptonic and quarkish structures.&nbsp; Such a theory naturally accommodates a kind of GR model of gravity.&nbsp; If we then also allow for some linear "Maxwellian" interaction between the structures, we get something more Newtonian. (Remember how Kaluza tried adding that fifth row and column to one of Einstein's tensors...)So if there are both linear and non-linear components to the gravitational interaction, could this help explain why neither Einstein's nor Newton's theory have proved fully satisfactory alone.We may still need to join some dots? <br /> Posted by nnunn</DIV></p><p>You know it is funny. I was sitting on the crapper today and I thought that EXACT VERY THING!!&nbsp;</p> <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You know it is funny. I was sitting on the crapper today and I thought that EXACT VERY THING!!&nbsp; <br />Posted by billslugg</DIV></p><p>But you had the presence of mind to flush.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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neilsox

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It's easier for me to comprehend the vastness of space outward than the depth of space inward.What is the smallest known particle? How much smaller does current theory predict?I visualize a fracal animation where as you zoom into an edge you&nbsp;see there are just more fractal edges and so on and so on. Is there infinite depth? <br />Posted by LacheLimbo</DIV><br />I was surprised no one mentioned the quark. Are they disappearing from modern physics? Supposedly a quark is 1/6 th of a proton, which used to be considered about&nbsp;1800 times smaller than&nbsp;an electron. I don't think we should assume size = mass, even if some physicists think that way. Let's not change the English language.&nbsp;&nbsp; Neil
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I was surprised no one mentioned the quark. Are they disappearing from modern physics? Supposedly a quark is 1/6 th of a proton, which used to be considered about&nbsp;1800 times smaller than&nbsp;an electron. I don't think we should assume size = mass, even if some physicists think that way. Let's not change the English language.&nbsp;&nbsp; Neil <br />Posted by neilsox</DIV></p><p>Quarks are alive and well and living in the nucleus, held there by the strong force.&nbsp; As far as I know they are also modeled as points.&nbsp; I believe that a proton is composed of 3 quarks m two "up" and one "down".<br /></p> <div class="Discussion_UserSignature"> </div>
 
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centsworth_II

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<font color="#666699"><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>As far as I know they are also modeled as points.<br /> Posted by DrRocket</DIV><br /></font>I take it you're not big on string theory. <div class="Discussion_UserSignature"> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I take it you're not big on string theory. <br />Posted by centsworth_II</DIV></p><p>I'm waiting for string theory to become a useful theory.&nbsp; So far it has provided some spectacular mathematics (major advances in classifying 4-manifolds for instance) but no new correct physical predictions.&nbsp; The so-called standard model treats the elementary particles as points.&nbsp; Maybe it is wrong, in fact we know that there is more to the story, but it is the best that we have at this time.</p><p>String theory could yet become a mature theory with real predictions.&nbsp; If it does, I am all ears.&nbsp; But at this point in time it is just speculation.&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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Tsurugi

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I take it you're not big on string theory. <br /> Posted by centsworth_II</DIV></p><p>String theory is neat, but I'm waiting to see if they will be able to isolate the Higgs Boson at the LHC this summer/fall.</p><p>Not to say that the Higgs would rule out ST, but it would be another validation of the Standard Model.</p><p>http://public.web.cern.ch/public/en/Science/Higgs-en.html </p> <div class="Discussion_UserSignature"> <p>-Tsu</p><p> </p><p><em>"If you're gonna be dumb, you gotta be tough."</em> </p> </div>
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I don't think your idea is gibberish, but I don't think it is reflected in an established useful theory --- yet.<br /> Posted by DrRocket</DIV></p><p>I think you're right.&nbsp; I did find another reference to the Planck length being a minimum in a different forum, but that individual was referring to the actual size of the photon and thus the wavelength couldn't be smaller.&nbsp; Not quite what I was thinking and his idea didn't get anywhere either.&nbsp; I alluded to something similar as he was by considering both the planck length and time, but alas... they are arbitrary numbers that may or may not be valid limits.</p><p>I then changed course and thought there might a Schwarzschild radius of a photon.&nbsp; I understand the photon is massless, but there is mass/energy equivalence and should apply.&nbsp; Too much energy and it collapses.&nbsp; I thought I struck gold with this PDF:&nbsp;</p><p><font face="arial,sans-serif" size="-1" color="black"> <font color="blue">http://arxiv.org/pdf/physics/0506093</font></font> </p><p>I kept up with the article ok until he/she started making substitutions.&nbsp; Switching spin and angular momentum didn't really make sense to me.&nbsp; And it seems later on he also substitutes other variable with Planck units.&nbsp; I'm familiar with the formula for the Schwarzschild radius, but I couldn't follow with all the subs made and why they were valid.</p><p>&nbsp;</p><p>Maybe if we looked at highest energies and temperature during the first Planck second, we might find the answer <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" />.&nbsp; But wouldn't that still limit us to one Planck length?&nbsp; Does the Compton wavelength and Schwarzschild radius even apply to photons?&nbsp; Odd little things these photons are...</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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derekmcd

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>String theory is neat, but I'm waiting to see if they will be able to isolate the Higgs Boson at the LHC this summer/fall.Not to say that the Higgs would rule out ST, but it would be another validation of the Standard Model.http://public.web.cern.ch/public/en/Science/Higgs-en.html <br /> Posted by Tsurugi</DIV></p><p>Last I checked, they were still waiting for the magnets to cool enough for insertion of the beams from their smaller accelerator to the LHC.&nbsp; I think they are shooting for insertion in late June or early July with the first collisions 5-6 months after that.&nbsp; (Takes time to build up the required energies for collisions worthy of 6 billions dollars.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" />) </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
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Tsurugi

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Last I checked, they were still waiting for the magnets to cool enough for insertion of the beams from their smaller accelerator to the LHC.&nbsp; I think they are shooting for insertion in late June or early July with the first collisions 5-6 months after that.&nbsp; (Takes time to build up the required energies for collisions worthy of 6 billions dollars.) <br /> Posted by derekmcd</DIV></p><p>Yep.&nbsp; I give much respect to anyone who can impart enough energy in a stream of protons to make it have the same impact as a 400ton train traveling at 150km/h.&nbsp; That is some <em>serious</em> juice. </p> <div class="Discussion_UserSignature"> <p>-Tsu</p><p> </p><p><em>"If you're gonna be dumb, you gotta be tough."</em> </p> </div>
 
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