# Why can't my hand go through my desk? (physics question) **URL:** \ **Category:** Factual Questions\ **Created:** [January 26, 2005, 10:54pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835 "2005-01-26T22:54:55Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![audio\_wizard](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@audio\_wizard](https://boards.straightdope.com/u/audio_wizard)\ **Post date:** [February 1, 2005, 11:55pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/61 "2005-02-01T23:55:56Z")
I disagree with Stranger on a Train’s beliefs. \*While this isn’t any more wrong than any other attempt to render quantum mechanics by the light of our experience in the natural world, I think it may offer a somewhat misleading impression of what the atoms and photons are actually doing. If you imagine the electrons shooting back and forth fast enough to nail any passing electron and then start running numbers on exactly how fast a particle of the diameter of electron would have to go in order to cover the “area” of its shell, you realize that it would be moving at huge multiples of the speed of light, and therefore should sell itself out to the Yankees as a shortstop. This is obviously not the case, and that is because there is nothing obvious about QM. \* this is absolutely right. Quarks move fast. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [February 2, 2005, 12:02am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/62 "2005-02-02T00:02:27Z")
> [@Whack-a-Mole](#): > > Ack…my bad. I was thinking of Quantum Tunneling where a particle that one would think had no chance of crossing a barrier actually may do so. The more mass the less likelihood of this happening but as close to zero as the answer may be the possibility is not zero (actually has a pretty good chance for the very, very small…for a human to do the same the odds are vanishingly small albeit not zero). The barrier the electron is going “through” isn’t a physical object; it’s an energy level that it doesn’t have enough momentum to achieve. Instead of somehow getting enough energy to hop over the “barrier”, it just…appears on the other side, stochastically-speaking, of course. The effect occurs because there’s a finite chance for the electron to “be” outside the barrier, even though it can’t get enough energy to go over it, and then when it is, it’s there, like the Cheshire Cat. Remember, as **Chronos** is on a mission to point out, _there is no particle!_ There’s just that a wave is sometimes best _conceptually treated_ as a particle because, like assuming a horse is a sphere, it makes the math easier. Some people think that, given the right conditions, this can occur on the macro level. If you do a search on Google for “Macroscopic Quantum Tunneling” you’ll get a few scholarly sites like [this](http://www.lassp.cornell.edu/ardlouis/dissipative/mqt.html) one and [this](http://www.stanford.edu/group/kgb/Research/mqtintro.html) one (that provide almost no information), and then a bunch of free energy/anti-gravity/tinfoil hat crap like [this](http://www.americanantigravity.com/unitelnw.shtml). I don’t think any knowledgable scientist will suggest that it can be used to bypass the front door of Fort Knox or flit a spaceship across the unimaginable distances between stars, though I do recall an '80s RPG (Traveller?) that used the concept. Some more information about QT [here](http://www.physicspost.com/articles.php?articleId=173). A simple explaination with nice pictures. Stranger ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [February 2, 2005, 1:18am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/63 "2005-02-02T01:18:15Z")
> [@Stranger On A Train](#): > > Some people think that, given the right conditions, this can occur on the macro level. If you do a search on Google for “Macroscopic Quantum Tunneling” you’ll get a few scholarly sites like [this](http://www.lassp.cornell.edu/ardlouis/dissipative/mqt.html) one and [this](http://www.stanford.edu/group/kgb/Research/mqtintro.html) one (that provide almost no information), and then a bunch of free energy/anti-gravity/tinfoil hat crap like [this](http://www.americanantigravity.com/unitelnw.shtml). I don’t think any knowledgable scientist will suggest that it can be used to bypass the front door of Fort Knox or flit a spaceship across the unimaginable distances between stars, though I do recall an '80s RPG (Traveller?) that used the concept. The link below does not debunk macro quantum tunneling as impossible. Rather they do the calculation to show it is just super-improbable. Near impossible is not the same as impossible…now if we can only come up with that Infinite Improbability Drive we’ll be all set! [sub]Anyone have a nice cup of really HOT tea handy?[/sub] > [@](#): > > The probability of an object tunneling through a barrier as predicted by the Schrodinger equation can be found by the equation > > P= esup[/sup] > > Where L is the width of the barrier and K is the wave number… > > \ > > So, if you were 50kg, and were attempting to tunnel through a 30 joule potential barrier… > > \ > > P= esup[/sup] = esup[/sup] > > … which is so small it is almost zero. So once again, for a human being the answer is: almost impossible. However for objects with extremely small masses (such as electrons) the probability can be quite high. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [February 2, 2005, 1:27am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/64 "2005-02-02T01:27:41Z")
> [@Whack-a-Mole](#): > > The link below… Guess it would help if I actually provided a link to my quote above. SOURCE: [What are the odds of me experiencing Quantum Tunneling?](http://www.physlink.com/Education/AskExperts/ae460.cfm) ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [February 2, 2005, 1:52am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/65 "2005-02-02T01:52:04Z")
> [@Crafter\_Man](#): > > When I slap my hand down on my desk, my hand comes to rest atop the desk. But if each atom in the desk is 99.99% nothingness, and each atom in my hand is 99.99% nothingness, shouldn’t my hand just go through it? > > I suspect the reason has something to do with electrical repulsion forces on the atomic level. Just wanted to get the straight dope on this. Mostly because neither you nor I understand physics. :rolleyes: ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [February 2, 2005, 11:29pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/66 "2005-02-02T23:29:39Z")
> [@Mangetout](#): > > Of course it’s much _more_ likely that a random, insignificant scattering of atoms in the desk and your hand are the right configuration for close flyby, whereas the rest aren’t. This is usually known as a _splinter_, right? 🙂 ---
**Author:** ![adityamenon](https://avatars.discourse-cdn.com/v4/letter/a/f04885/32.png) [@adityamenon](https://boards.straightdope.com/u/adityamenon)\ **Post date:** [January 26, 2011, 6:30am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/67 "2011-01-26T06:30:31Z")
I now know why organized religion is so successful as opposed to scientific thinking. Why people kid themselves into believing _all that_ ignorant stuff. Because the alternative explanation is so hard to comprehend that it is impossible to understand completely. Up until post #28, I thought I had understood everything that is happening, I had the “illuminated look on my face”, and then the stranger came along to wreck everything 🙂 Since the argument from that point is intelligible and unintelligible at the same time, much like the subject it discusses, I simply choose to believe the explanation given before #28. That the universe is made up of baseball-shrunk-to-scale particles that create the sense of touch by repulsion, and thus matter is solid at the macroscopic scale despite being mostly empty. Even that simplified explanation is quite impossible to explain in summary to the illiterate billions the human population is mostly made up of. So, everybody simply chooses to believe there’s a dude up there that made everything using “magic” - a force that most people except a few who know the dude up there better cannot control or harness. Besides, it’s comforting to believe that there’s always somebody looking out for the good and working against the evil. Wait, I don’t think good and evil matter to quantum mechanics - because they cannot be quantized 😃 ---
**Author:** ![racer72](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/racer72/32/3075_2.png) [@racer72](https://boards.straightdope.com/u/racer72)\ **Post date:** [January 26, 2011, 9:29am UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/68 "2011-01-26T09:29:18Z")
Did you happen to notice this thread died almost 6 years ago? ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [January 26, 2011, 4:42pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/69 "2011-01-26T16:42:02Z")
> [@Q.E.D](#): > > In fact, when you slam your hand down on the desk, no matter _how_ hard you hit it, nothing in your hand actually makes physical contact with anything in the desk. If the atoms of my hand never make actual contact with the atoms of the desk, I’d love to know:[ul][_]Is it possible to measure how close they get?[_]Do they get closer if I hid the desk hard, than if I hit the desk softly?[/ul] ---
**Author:** ![Punoqllads](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@Punoqllads](https://boards.straightdope.com/u/Punoqllads)\ **Post date:** [January 26, 2011, 5:09pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/70 "2011-01-26T17:09:00Z")
**Q.E.D.** has passed this mortal coil, unfortunately. ---
**Author:** ![Nunzio\_Tavulari](https://avatars.discourse-cdn.com/v4/letter/n/b9bd4f/32.png) [@Nunzio\_Tavulari](https://boards.straightdope.com/u/Nunzio_Tavulari)\ **Post date:** [January 26, 2011, 5:50pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/71 "2011-01-26T17:50:57Z")
> [@Punoqllads](#): > > **Q.E.D.** has passed this mortal coil, unfortunately. 1% of him passed away. The rest was just empty space anyway. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [January 26, 2011, 6:02pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/72 "2011-01-26T18:02:48Z")
> [@racer72](#): > > Did you happen to notice this thread died almost 6 years ago? But I’m still looking for an answer to my question! 😃 ---
**Author:** ![aldiboronti](https://avatars.discourse-cdn.com/v4/letter/a/9fc348/32.png) [@aldiboronti](https://boards.straightdope.com/u/aldiboronti)\ **Post date:** [January 26, 2011, 6:32pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/73 "2011-01-26T18:32:32Z")
Damn, bitten by a zombie again! Classic thread though, and boy are we ever glad that **Stranger On A Train** _did_ stick around! ---
**Author:** ![MOIDALIZE](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@MOIDALIZE](https://boards.straightdope.com/u/MOIDALIZE)\ **Post date:** [January 26, 2011, 6:38pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/74 "2011-01-26T18:38:31Z")
> [@Crafter\_Man](#): > > But I’m still looking for an answer to my question! 😃 Has your hand been stuck in a desk this whole time?! ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [January 26, 2011, 6:45pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/75 "2011-01-26T18:45:23Z")
> [@Nunzio\_Tavulari](#): > > 1% of him passed away. The rest was just empty space anyway. It’s all “empty space” and all filled by fields. However, in the case of the late **Q.E.D.** , the fields are still around, they’re just not aligned in a systemic form that we would think of as animated and sentient. Stranger ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [January 26, 2011, 6:57pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/76 "2011-01-26T18:57:58Z")
> [@Keeve](#): > > ]Is it possible to measure how close they get? Do you mean predict analytically, or actually measure? If the former, yes, it is possible within allowable precision to predict how close the nuclei could come to each other. Measuring the distance between the actually loci of the electrons that reside within the electron shells is not meaningful for reasons that are readily apparent only if you understand QED (the theory, not the poster). > [@Keeve](#): > > Do they get closer if I hid the desk hard, than if I hit the desk softly? Not unless you are hitting the desk hard enough to dislocate electrons from the valance (outer) shell. If you can turn your desk into a cloud of plasma, you should give yourself a cool name and buy a spandex jumpsuit, or else hire yourself out to ITER as they’re always on the lookout for fresh talent in the field of applied high energy physics. Stranger ---
**Author:** ![adityamenon](https://avatars.discourse-cdn.com/v4/letter/a/f04885/32.png) [@adityamenon](https://boards.straightdope.com/u/adityamenon)\ **Post date:** [January 26, 2011, 6:58pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/77 "2011-01-26T18:58:56Z")
I’m sorry, but this discussion was so engrossing and so central to my understanding of the world, that I had to sign up just to chip in my two cents 🙂 ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 26, 2011, 7:20pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/78 "2011-01-26T19:20:37Z")
> [@Stranger\_On\_A\_Train](#): > > The neutron star is more compact (denser) because the probability distribution of neutrons is much tighter by virtue of being much more massive. Beyond that, you lose any information about the individual particles and collapse into a singularity from which information (matter, light) cannot escape. Some believe, in theory (with some evidence), there can be another step here in which the star becomes a [Quark Star](http://en.wikipedia.org/wiki/Quark_star) (or Strange Star). If the gravity is sufficiently high the neutrons break down into their constituent quarks. Such a star would be consider a single hadron…albeit a hadron several miles across. ---
**Author:** ![Punoqllads](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@Punoqllads](https://boards.straightdope.com/u/Punoqllads)\ **Post date:** [January 26, 2011, 7:28pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/79 "2011-01-26T19:28:31Z")
Note to self: do not Google “large hadron” while at work. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [January 26, 2011, 7:29pm UTC](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835/80 "2011-01-26T19:29:53Z")
I never knew Quark had a several mile long hadron. [Previous page](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835.md?page=3) [Next page](https://boards.straightdope.com/t/why-cant-my-hand-go-through-my-desk-physics-question/286835.md?page=5)