As a neutrally charged particle, a photon shouldn't interact electrically with another charged particle. However, since photons are electromagnetic waves, they should interact with charged particles, both electrically and magnetically.  Is this because the average in time of the electric and magnetic fields is zero?  (physics student)
Two electrons, or an electron and a proton, interact with each other because of the Coulomb potential, which can also be seen in the Schrödinger equation (which is the equation that describes the motion for elementary particles).  But how do an electron and a photon interact? Why can a photon kick up an electron to a higher atomic orbital, or why is a photon emitted when an electron jumps down to a lower orbital? A photon do not have any charge, so the interaction cannot be caused by the Coulomb potential. So what is it that causes the interaction, and how does that affect the Schrödinger equation? (Or well, the relativistic version of the Schrödinger equation, since we're dealing with photons.)
Linux, find all files matching pattern and delete Looking to find all files (recursively) which have an underscore in their file name and then delete them via command line. I need to cite the journal "Sankhyā: The Indian Journal of Statistics" in a paper.  I would like to draw the ā character properly (i.e., I'd prefer, if possible, to avoid using some hack, such as \bar or \overline).  Question: How do I properly write ā in LaTeX?  I didn't have luck with  (after several attempts in both in capital and lowercase) nor The Comprehensive LATEX Symbol List (searching the file for "ā" and "india" revealed no hits). While building things I want to see the overlays from other modes so I can make better decisions. Can I lock an overlay somehow?  For example: When building roads I want to see the natural resources overlay. When zoning I want to see the wind overlay When do I need to invoke \phantomsection? What is the best way to tokenize/split a NSString in Objective-C? Consider there is a box of mass $m$ at rest on the floor. Most books give an example that we need to do a work of $mgh$ to lift the box $h$ upward.  If we analyze this work done, the external force acting on the box by us should be equal to the weight of the box. Therefore the net force is zero which in turn there is no acceleration. If there is no acceleration and the initial velocity of the box is also zero, how can the box move upward? How to achieve line break in simple $formula$-mode Getting an error while trying to script it, specifically "Cannot use VB for services."  Snippet and VB code block as follows:  Raw block (works within ArcMap): "\ftp\raw\YYYYMMDD\Files\Charles" +[NAME]+".ntf"  Snippet:      date = '"20160207"'      arcpy.CalculateField_management(outShp, "Link", '"\\\\ftp\\raw\\"' + date + '"files"' + "[NAME]"+ '".shp"', "VB", "")   Not sure what the issue is, somehow need to be able to insert the date and have it syntactically be correct (in either VB or python).  I didn't explain very well I have a column that contains a portion that is part of the hyperlink, so need to concatenate A column to the end of B column (with the partial path) to complete the link What's wrong with this query: INSERT INTO Users( weight, desiredWeight ) VALUES ( 160, 145 ) WHERE id = 1;  It works without the WHERE clause. I've seemed to have forgot my SQL. How do I install the latest stable version of Firefox? I want to install the latest Firefox on my Ubuntu (64bit) box.  What is the best way to do this? Is there a specific update site or should I download the binaries manually? If doing manually, in which directory should I put the files? In my home directory, or is there a better place? Can I use my powers for good? Select list of node titles for a view exposed filter How to check if value is in range of cells? I want to check if the value of a cell exists in a range of cells. How can I do this?  Just like you would be able to do "if value in list_of_values" in Python for example. How to transform negative values to logarithms? I would like to know how to transform negative values to Log(), since I have heteroskedastic data. I read that it works with the formula Log(x+1) but this doesn't work with my database and I continue getting NaNs as result. E.g. I get this Warning message (I didn't put my complete database because I think with one of my negative values is enough to show an example):   &gt; log(-1.27+1) [1] NaN Warning message: In log(-1.27 + 1) : NaNs produced &gt;    Thanks in advance  UPDATE:  Here is an histogram of my data. I'm working with palaeontological time series of chemical measurements, E.g the difference between variables like Ca and Zn is too big, then I need some type of data standardization, that is why I'm testing the log() function.   This is my How to find event listeners on a DOM node when debugging or from the JavaScript code? I have a page where some event listeners are attached to input boxes and select boxes. Is there a way to find out which event listeners are observing a particular DOM node and for what event?  Events are attached using:    Event.observe; DOM's addEventListener; As element attribute element.onclick. To my understanding, "Control" can have two meanings in statistics.   Control group: In an experiment, no treatment is given to the member of the control group.  Ex: Placebo vs Drug: You give drugs to one group and not to the other (control),  which is also referred as "controlled experiment".  Control for a variable: Technique of separating out the effect of a particular independent variable. Some of the other names given to this techniques are, " accounting for", "holding constant", "controlling for", some variable.  For example: In a Football viewing study (like or not like),  you may want to take out the effect of gender as we think gender causes bias, that is, male may like it more than female.     So, my question is for point (2). Two questions:  How do you "control"/ "account for" variables, in general. What techniques are used? (In terms of regression, ANOVA framework).   In above example, does choosing male and female randomly constitutes control? That is, is "randomness" one of the techniques for controlling other effects? pronoun agreement in neither nor Which one is correct?   Neither my friend nor I feel my best in the morning. Neither my friend nor I feel her best in the morning. Neither my friend nor I feel our best in the morning.    I already know that the verb agrees with the subject closer to the verb:   Neither my friends nor my brother understands me. (correct) Neither my friends nor my brother understand me. (wrong)   AND   Neither my brother nor my friends understand me. (correct) Neither my brother nor my friends understands me. (wrong) How many "Recommend Close" votes is too many? We had a rule check tonight that we couldn't answer. On the Pathfinder wiki I could only find info on natural 20s and 1s in regards to attack rolls and saves in combat.  Do they also apply to skill checks? Why is Harry Potter a half-blood?