Search found 212 matches

by Tub
Wed Dec 14, 2016 11:23 pm UTC
Forum: Science
Topic: What to Do With a Nearby Black Hole
Replies: 11
Views: 1697

Re: What to Do With a Nearby Black Hole

Unfortunately, the Schwarzschild radius is just 2M, so for a black hole with the predicted mass of Planet Nine, that would be a mere 9 cm. Needless to say, this is not measurable. Hm, I thought that'd just be an issue of bigger lenses and didn't do the math. Sure, it's small, but it's also very clo...
by Tub
Wed Dec 14, 2016 11:36 am UTC
Forum: Science
Topic: What to Do With a Nearby Black Hole
Replies: 11
Views: 1697

Re: What to Do With a Nearby Black Hole

Pretty much any free telescope would be pointed at it immediately. Mapping out its orbit (and making sure it won't collide with anything important), getting dark pictures, maybe being lucky enough to observe some infalling object. The most precise telescopes might be able to confirm or refute the ex...
by Tub
Thu Dec 08, 2016 2:58 pm UTC
Forum: Coding
Topic: Coding a Simple Data Entry App?
Replies: 16
Views: 1967

Re: Coding a Simple Data Entry App?

Your mistake is to assume that all programmers make decisions you would consider sensible. I've seen browsers who refuse localStorage on file urls. I've seen browsers who offer localStorage, but don't persist the data for file urls. I've seen browsers who do as you suggest. I'm sure there is a brows...
by Tub
Thu Dec 08, 2016 2:20 pm UTC
Forum: Coding
Topic: Coding a Simple Data Entry App?
Replies: 16
Views: 1967

Re: Coding a Simple Data Entry App?

I'd like to record them on my phone with an interface that's simple and easy to use even when your fingers are cold and not very precise. How do you feel about voice control? With a clearly defined input vocabulary (10 digits, dot, true, false, ...) it should be easy to train for maximum precision....
by Tub
Mon Dec 05, 2016 5:26 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1768: "Settling"
Replies: 50
Views: 5030

Re: 1768: "Settling"

This sound a lot less motivational when you take it as relationship advice. Depends on the relationship. DTMFA is sometimes the best advice, and sometimes hearing it from someone else is what one needs to get out of a bad relationship. Well, duh, there are relationships worth keeping and there are ...
by Tub
Mon Dec 05, 2016 4:49 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1768: "Settling"
Replies: 50
Views: 5030

Re: 1768: "Settling"

This sounds a lot less motivational when you take it as relationship advice.
by Tub
Mon Dec 05, 2016 9:39 am UTC
Forum: Hardware
Topic: HDMI to long distance
Replies: 5
Views: 1599

Re: HDMI to long distance

Where exactly does the cable go? You're saying 200 feet; that doesn't sound like it would stay in the same household. If it connects your PC to a monitor that's plugged into a different power network or leaves the building, then you do not want to use copper cable. You need galvanic isolation in eit...
by Tub
Fri Dec 02, 2016 3:23 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

A canonical representation will not catch all functional identical formulas, but many. Consider it a "best effort" solution. For compilers, one use for a canonical representation is common subexpression elimination - without a canonical form, many optimization opportunities would be overlo...
by Tub
Mon Nov 28, 2016 10:06 pm UTC
Forum: Science
Topic: Can you build a better thermos than empty space?
Replies: 4
Views: 1306

Re: Can you build a better thermos than empty space?

Ah, sure, but the universe keeps cooling down, so as long as the thermos cools slower, it will always be warmer, right? For a long time, but not forever. Eventually, the thermos will decay, rupture, and the whole system will reach the inevitable thermal equilibrium. Entropy is merciless. But the me...
by Tub
Mon Nov 28, 2016 11:30 am UTC
Forum: Science
Topic: How to Make a Blender Quiet
Replies: 27
Views: 2248

Re: How to Make a Blender Quiet

What you really need is a smart blender that can be remote controlled via a phone app while you're sitting a mile away in a bunker. Have you tried simple $1 earplugs yet? In my experience, they can make quite a difference. Unless your blender is diesel-powered, it might even be enough to reduce the ...
by Tub
Sun Nov 27, 2016 12:26 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

I[..]I decided to have 'False' and 'True' be 0 and 1. [..]Similarly, OR could be treated as addition... You can either guarantee that boolean values are 0 and 1, or you can accept any nonzero value as true. In the first case, addition will violate that guarantee by producing 1+1=2. You need additio...
by Tub
Mon Nov 21, 2016 3:16 pm UTC
Forum: Science
Topic: Toroidal star
Replies: 14
Views: 1547

Re: Toroidal star

Also, you could cheat this I think with dark matter - does it count as a torus if the donut hole is a blob of dark matter rather than being empty? Keep in mind that dark matter does not have an electric charge. The thing that allows you to hold stuff in your hand is electromagnetism - the electron ...
by Tub
Sun Nov 20, 2016 11:29 pm UTC
Forum: Science
Topic: Can you build a better thermos than empty space?
Replies: 4
Views: 1306

Re: Can you build a better thermos than empty space?

The cube-square law says that a larger thermos will take longer to reach thermal equilibrium. Heat energy is proportional to volume, heat loss is proportional to surface. But heat transfer is also proportional to the temperature difference, so there is no limit to the heat loss. A big thermos can ma...
by Tub
Tue Nov 15, 2016 11:04 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

Have you ever had the need to change the network configuration on a headless machine? Do you remember double-checking everything before accepting the new network configuration and rebooting? Do you remember cursing, when you finally realized that the machine has not come back up and will not come ba...
by Tub
Mon Nov 07, 2016 2:36 pm UTC
Forum: Science
Topic: Quantum Fluctuations questions
Replies: 21
Views: 3409

Re: Quantum Fluctuations questions

Thanks for partially clearing up my confusions about the casimir effect; I was just about to ask. So it's safe to say that the energy between the plates is less than the energy outside the plates, but it's not safe to say that it's negative. Unless you define the vacuum energy outside the plates to ...
by Tub
Sun Nov 06, 2016 9:28 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

These are the oldest compilers I could find, and they both warn by default. gcc 4.8.4 /tmp> gcc printf.cpp printf.cpp: In function ‘int main()’: printf.cpp:9:31: warning: format ‘%f’ expects argument of type ‘double’, but argument 3 has type ‘int’ [-Wformat=] printf("%f (%f)", foo(bar), 0)...
by Tub
Sat Nov 05, 2016 10:13 am UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

What kind of reliability "guarantees" do you have with any provider? The amount of redundancy is just another setting in your config file, analogous to a different contract with your hosting company. The provider has a proven record of having operated reliably for X years. That's not a gu...
by Tub
Fri Nov 04, 2016 11:47 pm UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

I'm currently playing around with duplicity (thanks for the "reminder" to set up my own backups, commodorejohn!). It seems to do exactly what I envisioned my backups to do, just better than a selfmade bash script would have done it. I'm almost glad I've been too lazy to implement that thin...
by Tub
Fri Nov 04, 2016 12:44 pm UTC
Forum: Science
Topic: Some help me with Calculation of impact speed please
Replies: 4
Views: 1235

Re: Some help me with Calculation of impact speed please

Jeff_UK wrote:hitting the side of a mountain at Mach 2 with +-1m/s vertical velocity still might be awfully inconvenient.

Unless the planet happens to rotate with a surface velocity of Mach 2 in the same direction. Then you're fine.
by Tub
Fri Nov 04, 2016 8:33 am UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

I'm going out on a limb here and going to say that most people don't care about my holiday photos. Maybe those who wish to target you with travel ads. Maybe those who wish to compile a list of countries you've been to to assign a score for the likelihood of you being a terrorist. Maybe those who wi...
by Tub
Thu Nov 03, 2016 11:55 pm UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

Have you considered our lord and saviour cooperative storage cloud ? No reliability guarantees AND you will have other people using your bandwidth just when you're trying to stream a movie or fight the boss in an online game? I like the premise, of course, but actual server hosting has its advantag...
by Tub
Thu Nov 03, 2016 10:14 pm UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

Well, FTP is ancient and really shouldn't be used anymore. I expect that FTP and SFTP are used as synonyms in that list. (Though age is not much of a problem with FTP. Being unencrypted is.) And I still argue that SFTP is inferior to a protocol like RSync, which will automatically check timestamps ...
by Tub
Thu Nov 03, 2016 9:23 pm UTC
Forum: The Help Desk
Topic: Cheap online storage with SFTP access?
Replies: 30
Views: 3259

Re: Cheap online storage with SFTP access?

I assume you already know the list on wikipedia with the handy "ftp" column ? but pretty prohibitive for the couple dozen gigs of stuff I don't know how rapidly your "stuff" is changing, but keeping a hardcopy in a different building and using the online service merely for increm...
by Tub
Thu Nov 03, 2016 7:08 pm UTC
Forum: Science
Topic: The Future of The Brain (2014)
Replies: 55
Views: 3644

Re: The Future of The Brain (2014)

I never said that neuroscience isn't useful (I greatly respect anyone who approaches an understanding of the human mind without invoking Freud). I just don't think it'll yield the kind of results that aph envisioned in the last paragraph of the first post. But we'll see. I'd love to be proven wrong ...
by Tub
Thu Nov 03, 2016 11:33 am UTC
Forum: Science
Topic: The Future of The Brain (2014)
Replies: 55
Views: 3644

Re: The Future of The Brain (2014)

There are very small brains that do qualitatively similar things to large brains As far as I'm aware, we have small brains that do small brain stuff, like image recognition. And we have our large brains that can also do small brain stuff. But the interesting parts of psychology are those where our ...
by Tub
Wed Nov 02, 2016 12:00 am UTC
Forum: Science
Topic: The Future of The Brain (2014)
Replies: 55
Views: 3644

Re: The Future of The Brain (2014)

I keep being told that I'm a pessimistic party pooper, but let me offer a counter-point anyway. I'm as exited as you about any new results, I just don't share your optimism about sudden radical breakthroughs or the transformation of related sciences. As far as we can tell, brains do not require magi...
by Tub
Sun Oct 30, 2016 1:45 pm UTC
Forum: Computer Science
Topic: Deliberately bad algorithms
Replies: 108
Views: 22226

Re: Deliberately bad algorithms

Yeah, that compression is going to be a bit lossy for anything longer than 20 bytes. It will most likely produce a hash collision instead of the original input.
by Tub
Wed Oct 26, 2016 12:55 pm UTC
Forum: Mathematics
Topic: Finding a Quadrilateral for N Points
Replies: 20
Views: 2471

Re: Finding a Quadrilateral for N Points

It's meant to be a counterexample. I've given you 6 points (the vertices of both triangles), try solving it. The symmetry of the points should make it easy to systematically check all possible solutions.
by Tub
Wed Oct 26, 2016 11:33 am UTC
Forum: Mathematics
Topic: Finding a Quadrilateral for N Points
Replies: 20
Views: 2471

Re: Finding a Quadrilateral for N Points

I think I have a construction for N=5 which always works. If the points are convex, it's easy. Otherwise, pick both points that are not on the convex hull (if there's only one, add a random other point), draw a line through both. You have three lines and three (convex) points remaining, and I think ...
by Tub
Wed Oct 26, 2016 9:29 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

Makes me wonder if perhaps complex software can never possibly be bug free. You don't need to wonder. Just as we cannot prove if a program halts, we cannot prove if it produces the right answers, or if it produces the right answers by any sensible means. We do have several verification systems (uni...
by Tub
Tue Oct 25, 2016 9:14 pm UTC
Forum: Computer Science
Topic: Degree for Coding
Replies: 6
Views: 1055

Re: Degree for Coding

Hello all. Coding and computer science are things I am fascinated by to a great extent. Fascination and motivation cannot substitute education and practice. Whether you're self-taught, using online courses or visit a college doesn't matter much, but you do need to put in those mystical 10.000 hours...
by Tub
Tue Oct 25, 2016 7:09 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

Wait until you realize that you're now also responsible for someone else's computer problems.
by Tub
Tue Oct 25, 2016 3:23 pm UTC
Forum: Mathematics
Topic: Finding a Quadrilateral for N Points
Replies: 20
Views: 2471

Re: Finding a Quadrilateral for N Points

Those points are not arbitrary. If you're given a non-convex set of points, things get messy. I have no proof, but a bit of doodling suggests that N=5 may be possible in the general case (read: I found no counterexample), but N=6 is not (read: I found no obvious way to draw a quadrilateral on this s...
by Tub
Mon Oct 17, 2016 2:52 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9547
Views: 1342676

Re: Coding: Fleeting Thoughts

#include <stdio.h> #include <time.h> int main() { clock_t t1 = clock(); const size_t size = 4e6; double *arr = new double[size]; for (size_t i=0;i<size;i++) { arr[i] = (i - 0.5) * 0.5; } clock_t t2 = clock(); double elapsed = (t2-t1) / (double) CLOCKS_PER_SEC; // we want to output at least one elem...
by Tub
Mon Oct 17, 2016 2:23 pm UTC
Forum: Mathematics
Topic: Proving angles are equal in a triangle in a circle.
Replies: 15
Views: 1429

Re: Proving angles are equal in a triangle in a circle.

Zohar wrote:To be fair, it's not explicitly stated AT is a tangent to the circle in the drawing, is it?

It's not explicitly stated that the round thing is a circle, either. Sometimes, you just got to have faith.
by Tub
Sun Oct 16, 2016 3:55 pm UTC
Forum: Mathematics
Topic: Proving angles are equal in a triangle in a circle.
Replies: 15
Views: 1429

Re: Proving angles are equal in a triangle in a circle.

To solve this, you need to know only two things: * the sum of the inner angles of triangles * a tangent forms a 90° angle to the radius. Given just that information, every relevant angle of the triangle can be expressed in terms of the blue angle. But something important is missing from the diagram,...
by Tub
Mon Oct 10, 2016 2:14 pm UTC
Forum: Science
Topic: V=IR - bad science or am I being thick?
Replies: 15
Views: 2128

Re: V=IR - bad science or am I being thick?

The higher the resistance the harder the battery has to work to maintain a usable voltage[...] True. If you need a constant voltage (because your transistors require a certain voltage to work), then higher resistance means you need higher current. A battery contains charge, which is I*t (current * ...
by Tub
Thu Oct 06, 2016 10:06 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1742: "Will It Work"
Replies: 50
Views: 4300

Re: 1742: "Will It Work"

I'm not familiar with portage, but with most package managers, in fact, dependencies are expressed as packages . Which transforms your statement into: "The packages are rarely the problem. Other packages are." portage is used by gentoo, which has three features that make package managemen...
by Tub
Wed Oct 05, 2016 8:38 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1742: "Will It Work"
Replies: 50
Views: 4300

Re: 1742: "Will It Work"

Not pictured, at the far bottom end of the graph: "Code on my local drives"
by Tub
Tue Oct 04, 2016 6:02 pm UTC
Forum: Computer Science
Topic: Deliberately bad algorithms
Replies: 108
Views: 22226

Re: Deliberately bad algorithms

One can "know" a very high busy beaver number with very little information: you just need a UTM and the winning turing machine. Both should fit inside the box until BB(10^30) or something. But to actually calculate the number (as required if you wish to use it in a sorting algorithm), you ...

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