kelseymh

In my comment, I was drawing an implicit historical parallel (i.e., to the Nazi concentration camps and subsequent Nuremberg trials). I do not favor the death penalty at all, for both moral and economic reasons.

http://en.wikipedia.org/wiki/B.S.

http://www.instructables.com/community/favorite-button/

A little bit, but not at the level a mathematician would recognize. As I understand it, a "fractal dimension" is a way of measuring the area of something which only partially covers the plane, like a twisty coastline or a maze.

Think of a square, and start drawing a line at the corner. If you just draw a simple straight line, or even a simple curved line, like an arc or an S-curve, from one corner to the opposite, that line doesn't cover any of the plane. It's just a simple 1-dimensional line.

Now make the line more and more twisty. Don't make closed loops or crosses, but zig-zag it back and forth, maybe with some big zig-zags and also a lot of little squiggles. The more squiggles you have, the more of the square you're "coloring in," right? If you can imagine making an "infinite number" of squiggles, as close together as possible, you could color the whole square that way. Such a "line," covering the whole plane, would be equivalent to the plane, and be 2-dimensional.

So fractal liines are all the ones in between, with lots of squiggles, big and small, but not an infinite number of them. Their "fractal dimension," expressed as a number between 1 and 2 (like 1.4 or 1.673502) is the fraction of the square that they cover with their squiggles.

One of the important features of a true fractal, such as a coastline or a river delta (as opposed to something you might try drawing with a pen) is what is called scale invariance. If you zoom out, and look at big features, the fractal looks a certain way -- it might have some characteristic number of branches, or squiggles, or relative thickness (for a river). Now zoom in, and look at smaller scale features. With a fractal, the features look just the same as before. And if you keep zooming in, they still loook the same. The way you would describe the fractal is the same (invariant) no matter what zoom (scale) you use to inspect it.

There are many such mathematical functions. Fractals aren't a "thing," they are a broad category. The most familiar, of course, is the Mandelbrot Set (look that up on Wikipedia). There are many simple little programs you can use to draw really cool pictures of it; just do a Web search.

I highly recommend the Wikipedia article on fractals. Besides being a good overview, it has links to additional information, software, and so on.

Of course there is. These are algorithms, which means they can be implemented in any sufficiently powerful programming language (of which Python is one). Consider it a homework problem in your study of Python to write such an implementation (and post a screenshot of the picture when you've done it).

Gobble, gobble.

You are correct!  You used the "?SORT=COMMENTS" filter.  I had gone back to answer some of those "has the most" questions when I had all the "Best of 2009" in hand.  So I got only 10/11 right.

I am not an employee of Instructables.  I'm just a user, albeit a productive one with some expertise.  If you have problems with the new layout, you could either post your comments to the forum threads where it was announced, or you could post a bug report if there is something broken (like the next button).

If you do decide to comment publicly, you might consider being specific, and if possible constructive.  Saying something "sucks" is not a good way to get anyone to listen to you or take you seriously (like your really stupid avatar, see what I mean?).  What specifically do you not like?  What specifically could be different?

What do you mean you can't post forum topics?  Other users don't seem to have that problem, although at least one has reported intermittent difficulty (he was able to post a forum topic complaining that he couldn't post).  If you do post a bug report about this, include your operating system and browser (including version).

Actually, I think your avatar (buckminsterfullerene, I believe) is pretty cool.  I was just making the rhetorical point :-/

The old search is still available, as a backup.  You have to go through the new interface first (which allows I'bles to collect stats on what's being searched and how often.  Once there, you can use the "graphical search" link to get the equivalent results the old way.

We've all been having probelms with comments evaporating.  It's hard to fix because it's not reproducible.

No, I haven't had that problem.  I was able to reproduce the pseudo-logoff from the new Google search, though.

Maybe they get bored :-?

Hello!

Hee, hee :-) It is a very interesting idea; thanks! I am really amused at the way they completely hide the problem of scale. Buried in the middle of a paragraph, they talk about "millions of picowatts." So with their technology, they can generate about a microwatt of power :-) Why, that's enough to light, um,....1/23 millionth of a CFL! Piezoelectric power generation has been explored (and there is a recent article about it) for generating power for MEMS or "nanotechnology" machines, but not for macroscopic electrical applications.

Not a capacitor.  It's called a voltage multiplier, and people use it for things like Jacob's Ladders.  It still conserves energy (look up "conservation of energy" in Wikipedia). 

Power is energy per unit time, so you can require equality of power in vs. power out to calculate conservation of energy.  Power in watts is equal to voltage times current in amperes.  For your example, 100V input at, say, 1A would give you 100 kV output at 1 mA.

You're quite welcome!  You ought to be able to find some examples of voltage multipliers (e.g., schematics) here on I'bles, for some of the high-voltage projects, if you're interested.  Good luck!

Sure. It's me sitting inside the BaBar detector during a major maintenance downtime. <br /> <br /> Here's the URL to BaBar's public-information Web site http://www-public.slac.stanford.edu/babar/ where you can find lots of links describing the kind of physics we did and why, and the different components of the experiment. <br /> <br /> You could also look us up via Google or Wikipedia.<br />

Um, excuse me?  You posted this to the Orangeboard of user kelseymh, and presumably you read my profile.  Exactly who or what is "howzit"?

:-P I really did try both http://www.instructables.com/member/howzit and http://www.instructables.com/member/Howzit, but both came back <strong>Error 400</strong>.<br />

This is a test of the editor's built-in spell checker.  I have not made any spelling, punctuation, or grammatical mistakes.  What does the spell-checker say?

Let's see whether last night's patch fixed the URL bug. Pasting from above:<br /> <br /> Here one http://www.yahoo.com/ in the middle of a line.<br /> <br /> Here's one<br /> http://www.google.com/<br /> on a line by itself.<br /> <br /> And now, here's one at the very end: http://www.instructables.com<br />

You weren't even trying. You were making further inappropriate comments in my personal space, where I have every right to delete them. If you want to apologize, then do so, either privately or publicly.

Thank Hubble :-)

P.S. I was able to reply to this by using the direct "reply" link from my COMMENTS profile list, not from my OB.

Huh. It's affected several of us (DJ created a bug report) since late June. It started out with just "busy" (high number of comments) OBs being unusable, but now seems to affect everything. The symptom is that neither the "Add Comment" nor the "Reply" buttons within existing comments do anything. No text box is opened. What browser and version are you using, that you don't see this?

Thanks! Your original reply did show up in my "comments" list. I probably should have acknowledged it (sigh...) but things have been pretty busy this week. Do you deal with stuff around Chalk River, then? My Canadian geography is sadly limited outside of Montréal or greater Vancouver.

Apologies for the horribly delayed reply... "southern Alberta (next to British Columbia)," so your territory includes Banff? One of the small number of places I really want to see before I die is the Burgess Shale. Kind of like ex-pat Britishers going back to their ancestral home (Olduvai Gorge and Laetoli are also on my list). I never got there while we were living in Vancouver :-(

Ummm...no, I don't think so. What instructable was that? "Huge amount" would be on the order of gigavolts, and it isn't just the quantity, it's the energy density that is important.

At SLAC, we make positrons by shooting a beam of GeV electrons into a block of tungsten. That produces what is called an "electromagnetic shower," a mixture of multi-MeV gamma rays, secondary electrons, and positrons.

You can visualize how the shower develops by considering just one electron hitting the block. As the electron passes by a nucleus, it gets deflected, and radiates off a photon via bremsstrahlung. That photon, which will probably be several tens of MeV, will pass by a nearby nucleus. In that interaction, it can pair-produce, turning into an e⁺/e^- pair (you need the nucleus to recoil in order to conserve energy and momentum). Now you have two electrons and a positron. All three of them keep going through the material, and interact similarly. Keep the process going long enough and you end up with hundreds of particles coming out the far side of the tungsten.

Ah. The whole thing is a joke. It sounds great, and somebody could (and maybe has) used the idea in an SF story. But basically it's technobabble at the same level as having the starboard plasma conduit rupture again, for the Nth time in Star Trek history.