Search found 11 matches

by ealloc
Thu Feb 04, 2016 3:45 am UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 27988

Re: What-If 0143: "Europa Water Siphon"

liquid cohesion can allow a siphon system to exhibit flow in excess of the barometric limits under which siphoning primarily operates. So in summary, you agree that atmospheric pressure is not required to make siphons work. A degassed water siphon can work up to 5m in vacuum. Therefore siphons don'...
by ealloc
Sun Jan 31, 2016 8:53 pm UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 27988

Re: What-If 0143: "Europa Water Siphon"

A possible test: Take a u-shaped glass tube greater than 76cm in height, submerge it in mercury to fill it, and then slowly pull it bent-end up out of the mercury, keeping the open ends submerged. If you can pull it up (in eath's atmoshpere) higher than 76cm without a cavity forming at the top, then...
by ealloc
Sun Jan 31, 2016 8:21 pm UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 27988

Re: What-If 0143: "Europa Water Siphon"

Oops sorry, you're right I linked an older paper of theirs (with the same theme). The Dec 2015 paper is at http://www.nature.com/articles/srep16790 . And by adding "rather than through atmospheric pressure" I am summarizing their argument in the introduction. As they explain, there are two...
by ealloc
Sat Jan 30, 2016 4:47 am UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 27988

Re: What-If 0143: "Europa Water Siphon"

I think the siphon in a vacuum question hinges on what the liquid does when the pressure drops to zero. Let's say there is an intermolecular force f between molecules in the liquid. Then (barring mistakes!) the formula for the maximum siphon height is h = (f/a + P) / (rho*g) where a is the area of i...
by ealloc
Fri Oct 17, 2014 5:15 pm UTC
Forum: What If?
Topic: What-If 0116: "No-Rules NASCAR"
Replies: 60
Views: 19743

Re: What-If 0116: "No-Rules NASCAR"

b) There are some really strong electro magnets in the vehicle that oppose the G direction to maybe counteract it. kind of like the levitating frog but used to hold (almost) everything in place? This is exactly what I'm thinking. We need to remember is that it's the Normal force that kills you, not...
by ealloc
Wed Apr 03, 2013 5:32 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1193: Externalities
Replies: 505
Views: 144685

Re: 1193: Externalities

Did anyone come up with a better method for finding approximate hash matches than just brute force hashing of a bunch of random crap? There is no other way - that's the point of a cryptographic hash function! I guess you could use some psychoology and a dictionary attack, but that wouldn't increase...
by ealloc
Wed Apr 03, 2013 5:05 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1193: Externalities
Replies: 505
Views: 144685

Re: 1193: Externalities

I used exactly the method described above and got aroun 900k hashes/s. Here's the full program: #include <stdint.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include "skein.h" char *target = "5b4da95f5fa08280fc9879df44f418c8f9f12ba424b7757de02bbdfbae0d4c4fdf9317c80cc...
by ealloc
Wed Apr 03, 2013 12:22 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1193: Externalities
Replies: 505
Views: 144685

Re: 1193: Externalities

pitareio wrote:For those of us who don't have Matlab handy right now, could someone post the value for n=400, 390, 380?


You should get scipy. It's better than matlab and free! The answers are

400 1.27986510e-12,
390 1.22124533e-14,
380 1.11022302e-16
by ealloc
Wed Apr 03, 2013 12:13 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1193: Externalities
Replies: 505
Views: 144685

Re: 1193: Externalities

Current best here is 399, though I was a bit late to the party having missed the first 18 hours. Has anybody worked out what the function for the probability to acheive a certain score with a single hash is? Would be interested to know. Someone posted a formula a few pages back : viewtopic.php?p=33...
by ealloc
Tue Apr 02, 2013 9:57 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1193: Externalities
Replies: 505
Views: 144685

Re: 1193: Externalities

In case anyone is wondering, you can easily figure out how much hashing power you need based on the fact that the distribution of hash scores is extremely well approximated by a gaussian with mean 512 and stdv of 16. So for example, a score of 390 is 7.625 stdvs from the mean, and plugging that into...
by ealloc
Wed Dec 12, 2012 5:46 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1145: "Sky Color"
Replies: 211
Views: 64839

Re: 1145: "Sky Color"

Here's my shot at the blue sky, and why it blue and not green or violet: First, note that the sun is a very hot black body and appears white to us. Black bodies start off red, then warm up to orange, then yellow, then white. In each step we are adding more color components and get closer and closer ...

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