Talk:Quantum tunnelling/Archive 2

Question Regarding Language

Hello. Sorry, I'm new to wikipedia, and haven't logged in. Just a couple of questions about the language used in the "Semi-classical Calculation" section. (Not trying to bust anyone's chops, here.) The language around the equations, as they begin, has what seems to be an effective and scholarly "voice." But as the math proceeds, the language becomes much more conversational: "Which is obviously only valid when you have more energy...", as a phrase, is used a couple of times and, from the perspective of a person new to the subject (or poor at calculus) isn't obvious at all. Later, the writer begins a section with "Now we can easily construct global solutions..." I think the explanations are actually *very* good, but the choice of language is wrong for the tone of a scientific piece. I'd suggest instead (from my first example) "This is only valid if there is more energy..." and for the second example, "From here, it is possible to construct global solutions..." Someone without the science/math background might flee the explanations if they think the equations are "obvious" or "easy." Just to make it clear: I think the original writer did a fine job! I'm only making a suggestion.

I second this post completely. Good job original writer! I have made some pretty extensive changes to this section. Be sure to comment on them.

Phancy Physicist (talk) 08:02, 15 July 2010 (UTC)

imaginary time

I would like to see some formulas. Especially a semiclassical imaginary time description. --MarSch 14:20, 26 October 2005 (UTC)

Consider it done(CHF 05:17, 27 October 2005 (UTC))

Ok I added all the major points to doing a semiclassical tunneling problem. And I put in the results of tunneling through a barrier. Amazingly Razavy misstated the WKB solution. Fortunately I know better. I think an imaginary time (instanton) derivation is a bit too black magic here. The WKB solution is easier to understand and is standard graduate level material. Oh crap wait a second, there already is a WKB article. Dangit (CHF 08:05, 27 October 2005 (UTC))

Small correction

"The idea behind quantum tunnelling is that the said particle has the capability to cross the infinite-energy barriers and exist on the other side. "

According to University physics by Young and Freedman, page 1531. A particle cannot tunnel through an *infinite* potencial barrier, but can tunnel through a barrier that has greater energy than the particle does. Also the equation that gives the probability of tunneling breaks down and goes to zero if you use infinity as the energy of the barrier. -- previously unsigned comment by 144.173.6.77 at 19:43, 23 January 2006.

This caught my attention, as well. Elsewhere on Wikipedia, it seemed to treat this issue as I would expect: e.g. see the Finite potential well article. It looks like this is the relatively recent edit in which the article was modified to include tunnelling through an infinite potential. Does someone familiar with this article agree that these changes should be removed?--GregRM 21:10, 3 February 2006 (UTC)

Yep, you can't tunnel through an infinite barrier (see particle in a box). It was this edit; I'm restoring the original and maybe clarifying it a bit. - mako 08:20, 12 February 2006 (UTC)

CDM and cold emission.

Is there any connection between the theory of cold dark matter and the notion of cold emission as used in article? If not, please explain. Thanks. Folajimi 17:38, 28 February 2006 (UTC)

I don't see any direct link other than the fact that something is cold. With the dark matter, it is simply cold. With the cold emission, one is saying that the emission didn't happen because you excited emitted particle up to make it emit. CHF 01:13, 4 March 2006 (UTC)

Thank you for taking the time to respond. Cheers. Folajimi 03:30, 4 March 2006 (UTC)

I don't find this article especially helpful. If a physics student wants to follow through the math involved, he's not going to go to a wikipedia article on the subject, and for anyone else it's pretty much just chicken-scratchings. I was looking for a general sense of what physicists believe to be the effects and implications of quantum tunneling - someone in a discussion was saying that quantum tunneling allows for the possibility of all the particles in a heat-dead universe to accidentally, as it were, tunnel their way to the same place and restart a big bang type event, and while there's nothing at all in this article that guides me toward any kind of sense of what is and what isn't quantum BS.

Unfortunately, even to get a rudimentary grasp of what tunneling is you have to go in to some mathematics. As I see it, the key to understanding tunneling begins with understanding the concept of a wavefunction. Then to show that the effect exists you have to know some differential equation stuff. Without that, the most you can say about tunneling in lay terms is that there is pretty much a nonzero probability for a particle to be found anywhere in space so that yes, there is a mind-bogglingly small but nonzero chance that all particles are found at one spot in the universe. But maybe there's a better way to explain it. Any suggestions? --UltraHighVacuum 20:58, 3 April 2006 (UTC)

spelling of tunneling

Apparently, "tunneling" is the correct spelling. Shouldn't we move this page to Quantum tunneling ? Fresheneesz 07:23, 8 May 2006 (UTC)

Comment - According to this edit summary, the spelling depends on American English vs. British English. I have no idea if this is correct, but it seems that the page has previously been moved from Quantum tunneling.--GregRM 12:23, 8 May 2006 (UTC)

Indeed it is a matter of American English vs. British English. Wikipedia policy states that in an article such as this (where there is no obvious link to a region/nationality), it is up to the original creator or first signigicant contributor to decide which dialect to use. Or, in simpler terms it doesn't matter as long as the alternative spelling points here. Canderra 02:41, 12 May 2006 (UTC)

Both spellings are correct, even in American English, see Merriam-Webster: [1] SpNeo 13:37, 12 August 2006 (UTC)

Can we move the page to Quantum tunneling, one 'l', since it's spelled that way in the first sentence? 4.242.239.61 (talk) 20:37, 15 April 2009 (UTC)

micro and nanoscopic

The first sentence includes "micro and nanoscopic", should this be "micro- and nanoscopic"? Arthena^(talk) 18:57, 31 October 2007 (UTC)

Subheadings

Why have these been removed? The paragraphs now run into each other with no sense or explanation of what they are. I'll this talk page check later this evening and put them back if noone has any problems with that. Bozwell89 (talk) 16:55, 21 February 2008 (UTC)

Removed by an anon with no reason. — Laura Scudder ☎ 17:24, 21 February 2008 (UTC)

Pop Culture Section

Why no mention of The One? --Datalyss 07:12, 2 August 2008 (UTC)

Feel free to add it yourself if you feel it is relevant. Deamon138 (talk) 19:34, 2 August 2008 (UTC)

Unless someone can cite a specific issue number where Kitty Pryde's powers were specifically referred to as being a result of quantum tunneling, I am removing this from the pop culture section. —Preceding unsigned comment added by 70.164.228.9 (talk) 12:03, 12 September 2008 (UTC)

Meaning of this sentece?

"Wave-effects exactly analogous mathematically to those to which quantum mechanics gives the name "tunneling" can occur with Maxwell's wave-equation (both with light and with microwaves), and with the common non-dispersive wave-equation often applied (for example) to waves on strings and to acoustics."

Is the section in bold missing a word? That phrase seems to make no sense.

--97.100.4.70 (talk) 02:34, 23 March 2009 (UTC)

Wording now modified to: "Wave coupling effects mathematically equivalent to those called "tunneling" in quantum mechanics can occur...." Hope this is clearer (RGForbes (talk) 11:52, 27 March 2009 (UTC)).

Tunnelling or Tunneling

I noticed the views on the spelling of tunnelling/tunneling in a section above. According to what I read there, British-English dictates that it be spelt with two l's, but American-English is fine for either one or two. I'm not too bothered if American-English is used, however I would prefer the two l version because (aside from the fact that I am English) the spelling with two l's is accepted in both versions of English, whereas one l is only accepted in the US. However, my main point is that there appears to be a contradiction with the spelling in this article, namely that it is titled using the word tunnelling, but has in the very first line, the single l version. Surely we must be consistent and use one style throughout an encyclopaedia article? Deamon138 (talk) 20:52, 12 June 2008 (UTC)

In fact nearly all of the instances of this word in the article are with a single l, yet there are two l versions here too along with the title. Some consistency is in order I think. Deamon138 (talk) 20:55, 12 June 2008 (UTC)

I didn't get any response so I've made all tunnelling contains two Ls to match the title. Feel free to tell me if you object. Deamon138 (talk) 05:49, 22 June 2008 (UTC)

I object. It should be one L throughout since someone keeps changing the whole article to one L. Change the title back, too. 4.242.147.171 (talk) 20:56, 15 April 2009 (UTC)

New Changes - March 2009

Hi! I wanted to link this page to the page on field electron emission (which I have just updated, as I am an "expert" on this), but I thought this page needed updating to. I hope no one will mind, but I have deleted the whole "simple explanation" section, as bits of it are factually incorrect. In particular, tunneling is a process in which (in all normal cases) the tunneling object neither gains nor loses energy. I have also used the first section to link quantum mechanical tunneling to the analogous phenomena that occur with other wave-equations - as I think that this is a good way in to the subject. I have created a new section "some basics". In this I have put in some discussion about "wave-particle duality" - though I don'r call it that - and some information about why we have to use semiclassical approximations and about the present state of (J)WKB type theory. I am not sure that these two sections are in their best final form yet, but I think they will do for now.

More generally, I do wonder if an article of this kind needs to include quite such a detailed mathematical derivation of (one of the non-general forms of) the JWKB approximation. It seems likely to go over the heads of everybody except graduate physics students. However, I done nothing about this. What I do think is that it might be useful to put in an extra section before it, giving a very brief account of the final formulae associated with the JWKB approximation, as I understand them. I plan to do this later. (RGForbes (talk) 12:51, 11 March 2009 (UTC))

Extra Space

Why is there extra space at the top? Fix.174.3.98.236 (talk) 09:04, 10 February 2010 (UTC)