I've recently understood de Broglie's hypothesis, and I understand that a necessity for electrons to show diffraction is that the size of the aperture they pass through must be of the order of their de Broglie wavelength. So exactly what would happen if (if) I were to walk through a door of a size of the order of my de Broglie wavelength? If a number of people of the same order of masses did so?
Many introductory quantum mechanics textbooks include simple exercises on computing the de Broglie wavelength of macroscopic objects, often contrasting the results with that of a proton, etc.  For instance, this example, taken from a textbook:     Calculate the de Broglie wavelength for      (a) a proton of kinetic energy 70 MeV      (b) a 100 g bullet moving at 900 m/s   The pedagogical motivation behind these questions is obvious: when the de Broglie wavelength is small compared to the size of an object, the wave behaviour of the object is undetectable.  But what is the validity of the actual approach of applying the formula naively? Of course, a 100g bullet is not a fundamental object of 100g but a lattice of some $10^{23}$ atoms bound by the electromagnetic force. But is the naive answer close to the actual one (i.e. within an order of magnitude or two)? How does one even calculate the de Broglie wavelength for a many body system accurately?
When to spell out numbers It is generally believed and claimed that quantum computers can outperform classical devices in at least some tasks.  One of the most commonly cited examples of a problem in which quantum computers would outperform classical devices is $\text{Factoring}$, but then again, it is also not known whether $\text{Factoring}$ is also efficiently solvable with a classical computer (that is, whether $\text{Factoring}\in \text{P}$).  For other commonly cited problems in which quantum computers are known to provide an advantage, such as database search, the speedup is only polynomial.  Are there known instances of problems in which it can be shown (either proved or proved under strong computational complexity assumptions) that quantum computers would provide an exponential advantage? is a simple way to script small GUIs.  Can anyone give a nice example with a button and a text widget. When the button is pressed should a shell command be executed and the output piped to the text widget.  If you have other nice and clean examples for useful tasks, please add them too. Family in GLM - how to choose the right one? When modeling data sampled in the field, I often come across the problem of determining the Family of the dependent variable for GLM (or GLMM). An example: in an ecological study, I have ~ 60 patches.  I have sampled territories of an animal species within these patches as well as a set of explanatory variables.  The number of territories per patch (NTP) is the dependent variable in a GLM.   NTP is integer with values between 0 and 14:      How can I test for the family of NTP?  Any help appreciated as this is an issue many ecologists come across each time they conduct statistical analysis. Start + Gerund vs Start + Infinitive: is there a subtle tense difference? Is there a subtle difference between these fragments:  Jack walked over to the car, opened the door, and started to look for the aspirin vial in the glove compartment. Jill looked on skeptically. Jack walked over to the car, opened the door, and started looking for  the aspirin vial in the glove compartment. Jill looked on skeptically. Recurrence relation for number of ternary strings that contain two consecutive zeros The question is: Find a recurrence relation for number of ternary strings of length n that contain two consecutive zeros.    I know for ternary strings with length one, there are 0. For a length of 2, there is just 1 (00), and for a length of 3, there are 5 (000,001,002,100,200).    I did a similar problem, finding a relation for the number of bit strings of length n with two consecutive zeros: $$a_n = a_{n-1} + a_{n-2} + 2^{n-2}$$    Since you can add "1" to the end of all the $a_{n-1}$ strings, "10" to all the $a_{n-2}$ strings, and "00" any string of size $n-2$.    For the ternary string problem, I'm pretty sure you would replace the $2^{n-2}$ with $3^{n-2}$, but confused about the other terms of the relation. My guess is that it would have the coefficient $2$ in front of the other terms, since you can add either $1$ or $2$ to the end of $a_{n-1}$ and either $01$ or $02$ at the end of $a_{n-1}$.    So I believe the answer for the relation is: $$a_n = 2a_{n-1} + 2a_{n-2} + 3^{n-2}$$    How does that look? Building where clause based upon parameters zsh I/O redirection: redirecting and then piping; what is going on? Show that $S$ is compact. Let $A \in M_n(\bf C)$ and let   $S=\{ A \in M_n(\bf C) : A=A ^*$ and  $\rho (A) \leq 1 \}$, $\rho(A)$ denotes spectral radius of $A$.     Show that $S$ is compact subset of $M_n(\bf C) \cong \bf C^{n^2} $ with usual topology.    $S$ is subset of $\bf O_n(C)$ which is compact so I think its enough to show that $S$ is closed.Please help. For example, "dude," "man," "buddy," "pal," etc, when used to stand in for someone's name.  "Hey, pal, how's it going?"  Is there a word for terms like these?  Or is "colloquialism" as close as we can get? Shouldn't this be a pretty straightforward operation? However, I see there's neither a size() nor length() method. How can I get apt to use a mirror close to me, or choose a faster mirror? Downloading from the main Ubuntu archive is slow even when it's not release day, how can I get apt-get to automatically use a mirror that is close to me? Making voltmeter accepting bipolar input voltage, using a microcontroller I want to build a very simple voltmeter using ATMEGA328 ADC. I can successfully measure up to 20v (using a voltage divider), but the problem is, I don't understand how to measure the voltage properly, if negative and positive terminals are switched.   Only way I could think of is adding another ADC input which is responsible for measuring the 'inverted voltage'. The join both ADC inputs, but add diodes in between, so one channel works with (+-) and the other channel works with (-+) and then 'merge' the input from both channels using code. Then I should be able to measure things like sin wave for example (where polarities switch).   Is the concept correct or is there a better way to do this? Thanks! Lately it's happening to me this:  After completing one or more "First Posts" reviews, I go back to the Review Section main page:   And the post counter shows that there are still posts to review. I click the link to review them, but there is nothing.  Refreshing the page doesn't solve the issue: it shows the wrong number again. I am currently looking at the various libraries that I can use to show a map in my custom Android App. I have found several like Mapsforge, OSMDroid, ArcGIS runtime for Android, Google Maps for Android and so on. I'm sure that I am missing a few.   Is there a comparison chart somewhere about the differences in functionalities and pros and cons of each one?   If there isn't one, we could make this question community wiki, to serve alongside  &amp; . Formatting each part/section/subsection Are there some magic lines to be placed in the preamble that would, like in CSS,  specify how each generic section or subsection in the whole document should be formatted? Why use "the" for oceans/seas/rivers etc. but not lakes? Possibly two questions in here: Are these sentence constructions logical, and if they are, why are they different?     I swam across the Ocmulgee River.   I swam across the Pacific Ocean.   I swam across the Red Sea.   I swam across Lake Winnipeg.   I can't think of a way of phrasing the lake example while using an article with a proper noun. I thought at first it was because Lake Winnipeg is different; it's generic portion (the "Lake") comes first and the name of that body comes second, but I swam across Falls Lake is the same.   Yet the sentence I swam across the lake sounds right to me. ...Why? How do you remove duplicates from a list whilst preserving order? Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question: Prevent ligatures in Safari (Mavericks/iOS7) via CSS When are "if" and "whether" equivalent?