Search found 93 matches

by 0SpinBoson
Mon Oct 20, 2008 3:23 pm UTC
Forum: Science
Topic: Science Fair ideas
Replies: 5
Views: 1407

Re: Science Fair ideas

For inspiration, I find it a good idea to go on youtube, type in science fair, and see what comes up. Pick something interesting, and do something related or extend what they did. Mythbusters is also a great source of ideas. And, if all else fails, show people a gyroscope. They're like magic, but us...
by 0SpinBoson
Mon Oct 20, 2008 3:16 pm UTC
Forum: Science
Topic: acceleration on an inside lane
Replies: 16
Views: 2066

Re: acceleration on an inside lane

Regarding running, it might be as simple as the fact that turning is harder than running straight, and if you pick an inside path you're done with your turn faster. Also, if you're not required to keep running in your lane, then it's harder for people to pass you if you're in the inside lane. Regard...
by 0SpinBoson
Tue Sep 30, 2008 7:51 pm UTC
Forum: Science
Topic: Light switch circuitry
Replies: 5
Views: 3454

Re: Light switch circuitry

You need two switches known as DPST (or STDP), it's a switch that connects one wire to two, and switches between them. Put the lightbulb next to the power supply, and connect the two switches like this: (attempted ascii art) (off state) ______________ / --------(S) (S)----------- _____________ / you...
by 0SpinBoson
Mon Sep 08, 2008 2:39 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0473: "Still Raw"
Replies: 238
Views: 40965

Re: "Still Raw" Discussion

Unfortunately, redefining pi isn't as easy as it sounds... It doesn't just crop up in constants and equations, but it also comes out of an insane number of mathy things. In physics we just deal with it by including it in constants (see http://www.wikipedia.org/wiki/Hbar ) and setting those constants...
by 0SpinBoson
Wed Sep 03, 2008 4:51 pm UTC
Forum: Computer Science
Topic: Listing all permutations
Replies: 10
Views: 5505

Re: Listing all permutations

Thanks everyone!
by 0SpinBoson
Tue Sep 02, 2008 5:37 pm UTC
Forum: Computer Science
Topic: Listing all permutations
Replies: 10
Views: 5505

Re: Listing all permutations

No, let me clarify. I have a set of items, and number them 1...N. As an example, take the numbers 1 through 4. I am looking for an easy way to generate (in any order)

1234
1243
1324
1342
1423
1432
2134

etc
by 0SpinBoson
Tue Sep 02, 2008 4:01 pm UTC
Forum: Computer Science
Topic: Listing all permutations
Replies: 10
Views: 5505

Listing all permutations

So a long time ago I learned an easy way to list all permutations of a set of objects, and I can't for the life of me recall it. Can anyone shed any light on this?
by 0SpinBoson
Thu Aug 28, 2008 2:07 am UTC
Forum: Science
Topic: GR question
Replies: 21
Views: 1721

Re: GR question

I was thinking just two. I came up with something though -- contract the vector with a matrix, then take the trace.
by 0SpinBoson
Wed Aug 27, 2008 11:49 pm UTC
Forum: Science
Topic: GR question
Replies: 21
Views: 1721

Re: GR question

Why not map all vector pairs to -1. Thats fails two of the metric requirements, but it still constructs a scalar quantity. I guess the question is, what do you want your function to do other than not be a metric? I'm afraid I don't understand this one. Think orientation. Let me think in 3d space fo...
by 0SpinBoson
Wed Aug 27, 2008 9:27 pm UTC
Forum: Science
Topic: GR question
Replies: 21
Views: 1721

GR question

So I came across something today... the problem was to write down a scalar quantity that can be constructed from vector quantities without use of a metric. The only thing I can think of is a comparison-like operator, and I'm sure that's not what the idea was. Anyone have any good ideas? I've thought...
by 0SpinBoson
Fri Jul 11, 2008 12:32 pm UTC
Forum: Science
Topic: Bicarb and Vinegar - revisited?
Replies: 16
Views: 2821

Re: Bicarb and Vinegar - revisited?

If I'm not mistaken horribly, that reaction produces CO_2. It's a gas and expands, so yeah, if the can is closed then it will. I recommend a safety valve to avoid this http://www.youtube.com/watch?v=JmJoyuUJj2Q
by 0SpinBoson
Fri Jul 11, 2008 11:52 am UTC
Forum: Science
Topic: Telling a (much) more senior scientist he is WRONG
Replies: 15
Views: 2143

Re: Telling a (much) more senior scientist he is WRONG

Again, you can take the approach of "Hey Dr. Whatsyourname, how come we use the whole spectrum to calculate the standard deviation, as opposed to my silly notion of using the peaks?"
by 0SpinBoson
Fri Jul 11, 2008 10:26 am UTC
Forum: Science
Topic: Nucleus stability depending on electron cloud?
Replies: 10
Views: 2185

Re: Nucleus stability depending on electron cloud?

In a nutshell, quantum mechanics. But, for a more classical picture, note that the p orbitals have a finite probability just outside the origin. But if the three P orbitals are filled, don't they add up to make a sphere of probability? They make a cloud, yes, but it's not spherical. It's \sum_m Y^{...
by 0SpinBoson
Fri Jul 11, 2008 10:22 am UTC
Forum: Science
Topic: Telling a (much) more senior scientist he is WRONG
Replies: 15
Views: 2143

Re: Telling a (much) more senior scientist he is WRONG

Depends on the person. Personally, I don't mind being shown that I had a bug in my code...it saves my butt. That being said, see if you can word it in the form: "I don't quite understand why you did it this way, could you explain?" If that doesn't work, you have to be a bit stronger, but i...
by 0SpinBoson
Thu Jul 10, 2008 4:07 pm UTC
Forum: Coding
Topic: testing for palindromes with absolutely brutal test data
Replies: 36
Views: 3915

Re: testing for palindromes with absolutely brutal test data

This sounds like a project euler problem...what compiler do you use? Good compilers should automatically do things like the suggestion above. What you could do, and this might be useful, is generate two arrays at the beginning of your code. Array one is the original text with all non-alphas removed,...
by 0SpinBoson
Wed Jul 09, 2008 4:21 pm UTC
Forum: Science
Topic: Imaginary space solutions to the Shrodinger equation?
Replies: 6
Views: 1242

Re: Imaginary space solutions to the Shrodinger equation?

[beats dead horse]

There's nothing in the Schrodinger equation that says solutions have to be real or not. The solutions are wavefunctions, which are only defined up to a (complex!) phase factor anyway, so I can make ANY solution of Schrodinger's equation imaginary.
by 0SpinBoson
Wed Jul 09, 2008 4:15 pm UTC
Forum: Science
Topic: Acceleration and displacement; relation.
Replies: 14
Views: 2110

Re: Acceleration and displacement; relation.

My apologies to the OP, I didn't read his post thoroughly enough. This is much harder, yes.

If the line doesn't pass through the center of the earth, wouldn't it be deviated away from a straight line? Assuming you can pass through whichever way you want, you might get some other closed path....
by 0SpinBoson
Tue Jul 08, 2008 8:58 am UTC
Forum: Science
Topic: Acceleration and displacement; relation.
Replies: 14
Views: 2110

Re: Acceleration and displacement; relation.

Unless you know what you're doing, don't separate differentials like that, it leads quickly to trouble.
To start with, what do you know about how a, v, and x are related? You got that [math]a=\frac{dv}{dt}[/math], how about x? When you've got those, try integration directly.
by 0SpinBoson
Mon Jul 07, 2008 3:15 pm UTC
Forum: Science
Topic: Train that doesn't stop
Replies: 17
Views: 2678

Re: Train that doesn't stop

I think that's why they went with the top-design, instead of in front. It's relatively easy to couple magnetically that way.
by 0SpinBoson
Mon Jul 07, 2008 10:48 am UTC
Forum: Science
Topic: The possibility of bullet-bending -- WANTED
Replies: 49
Views: 10288

Re: The possibility of bullet-bending -- WANTED

Dobblesworth wrote: where 'bullets were counter-fired at each other and collided directly head-on', would make one awesomely epic Mythbusters episode.


Mythbusters did it! :-)
by 0SpinBoson
Mon Jul 07, 2008 10:46 am UTC
Forum: Science
Topic: What do you think we will see at the LHC?
Replies: 160
Views: 20548

Re: Question about the Large Hadron Collider

The Higgs boson is what gives other particles mass, in a sense, by the amount of interaction they have with the Higgs field. Things like photons do not interact with the field, and so have no mass. Other things, like golden retrievers, interact with the Higgs field and drag a certain amount of Higgs...
by 0SpinBoson
Mon Jul 07, 2008 10:10 am UTC
Forum: Science
Topic: evolution: hard to fathom instances
Replies: 219
Views: 43609

Re: evolution: hard to fathom instances

They don't have enough sex at all, or they don't have enough sex in captivity? Because there are many many animals that have a lot of trouble breeding in captivity. Regarding Pandas, the problem I see with them is that they don't recognize their babies are being part of them. Seriously, I saw a vid...
by 0SpinBoson
Mon Jul 07, 2008 8:51 am UTC
Forum: Science
Topic: Might gravity not be considered a force?
Replies: 28
Views: 3766

Re: Might gravity not be considered a force?

Just to clarify one point, it is possible to mesh (at least SR) with Quantum Mechanics. It's called Quantum Field Theory, and its particular variants (Quantum Electro-Dynamics, Quantum Chromo-Dynamics, Klein-Gordon scalar field theory, etc). The problem lies in GR or even Newtonian gravity. We envis...
by 0SpinBoson
Fri Jul 04, 2008 12:22 pm UTC
Forum: Science
Topic: Nucleus stability depending on electron cloud?
Replies: 10
Views: 2185

Re: Nucleus stability depending on electron cloud?

I don't understand why the electron cloud would have an effect, especially in a single atom with only s orbitals filled, or all three P orbitals. In those cases, the electrons are in spheres around the nucleus and should therefore have no net effect on the nucleus. What am I missing? In a nutshell,...
by 0SpinBoson
Wed Jul 02, 2008 2:41 pm UTC
Forum: Science
Topic: Train that doesn't stop
Replies: 17
Views: 2678

Train that doesn't stop

So I ran across this (Warning: has a video)

http://www.carectomy.com/index.php/Trai ... ever-Stops

and thought I'd share. Enjoy.
by 0SpinBoson
Tue Jul 01, 2008 11:03 am UTC
Forum: Science
Topic: Beginner particle question about leptons
Replies: 16
Views: 2299

Re: Beginner particle question about leptons

The idea of it being made of clay works for nuclear decay (most of the time), but it doesn't fly for quantum particles. Maybe the quantum mechanics description will help. Think of a ball (with enough energy) rolling back and forth between two holes. If one hole larger, it'll spend more time there, o...
by 0SpinBoson
Tue Jul 01, 2008 10:55 am UTC
Forum: Science
Topic: metallurgy in zero gravity
Replies: 20
Views: 5093

Re: metallurgy in zero gravity

by 0SpinBoson
Tue Jul 01, 2008 10:50 am UTC
Forum: Science
Topic: car on a treadmill
Replies: 28
Views: 3673

Re: car on a treadmill

Sorry, that's right. I was working in the reference frame of the ground.
by 0SpinBoson
Mon Jun 30, 2008 5:39 pm UTC
Forum: Science
Topic: What is parametric instability?
Replies: 1
Views: 921

Re: What is parametric instability?

Just a guess:

Consider the energy E of your system as a function of your parameters [imath]{x_i}[/imath]
Take one of them, say [imath]x_3[/imath], and consider the derivative (assuming the first derivative is 0)
[imath]\frac{d^2E}{dx_3^2}[/imath]. If it's negative, then it's an unstable system.
by 0SpinBoson
Mon Jun 30, 2008 1:01 pm UTC
Forum: Science
Topic: car on a treadmill
Replies: 28
Views: 3673

Re: car on a treadmill

Just to make this clear: the car on the treadmill initially really does not have any kinetic energy. Sure, the wheels have some, but a simple order of magnitude estimate will show that it is very small compared to the kinetic energy cars normally have. If the car stops driving, then the treadmill ha...
by 0SpinBoson
Mon Jun 30, 2008 12:36 pm UTC
Forum: Science
Topic: The missing mass of nucleii
Replies: 12
Views: 1991

Re: The missing mass of nucleii

AFAIK, and I am not an expert, the extra mass is really the binding energy of the nucleus.
by 0SpinBoson
Fri Jun 27, 2008 9:07 am UTC
Forum: Science
Topic: Why are people obsessed with gold?
Replies: 51
Views: 5512

Re: Why are people obsessed with gold?

Gold foil is used on satellites and spacecraft to shield the sensitive electronic innards against radiation, right? Perhaps nuclear missiles are hardened against EMP or other interference using gold foil? So how exactly does that work? Does the induced current go just through the gold rather than t...
by 0SpinBoson
Fri Jun 27, 2008 8:52 am UTC
Forum: Science
Topic: Opinions/problems on a "force field"
Replies: 41
Views: 6082

Re: Opinions/problems on a "force field"

RAPTORATTACK!!! wrote:well the magnet would work on all matter right? everything conducts to some extent.


Incorrect. Insulators, in general, have rather large bandgaps. The most you could do is induce local dipoles. I still think a piece of rock would blow right through everything electric/magnetic.
by 0SpinBoson
Fri Jun 27, 2008 8:43 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2958
Views: 721880

Re: Common Questions

Is anyone else besides me really bothered by people continually bringing up the "Oh, that's what we say now, but XX years ago everyone knew the earth was flat" argument? This isn't meant to offend the poster above, but I hear it alot (esp. related to FTL stuff) and it drives me up a wall. ...
by 0SpinBoson
Tue May 20, 2008 8:38 pm UTC
Forum: Science
Topic: Falling object distance; please help a DM in need?
Replies: 24
Views: 2768

Re: Falling object distance; please help a DM in need?

I've had so many math/physics things come up during D&D sessions. We've had to work out whether someone would hit a flying monster with a cone based on trigonometry, and I've had to explain to a particularly stubborn player that no, moving diagonally 3 squares isn't the same distance as moving s...
by 0SpinBoson
Fri May 16, 2008 10:04 pm UTC
Forum: Mathematics
Topic: 'Average Angle'
Replies: 15
Views: 4539

Re: 'Average Angle'

Here's another way: Take each angle \alpha as a unit vector with direction \alpha as measured from the x axis. Resolve components, add them all, find the overall direction, divide by the number.
by 0SpinBoson
Fri May 16, 2008 9:57 pm UTC
Forum: Mathematics
Topic: Sphere -> Cartesian mapping
Replies: 16
Views: 2090

Re: Sphere -> Cartesian mapping

Earth basically spherical, at least for points a reasonable distance away from the poles. If you expand it in spherical harmonics you find that almost all the weight is in Y_{00}.

I have to agree that to solve TSP you don't need a map. Just distances, however you wish to define them.
by 0SpinBoson
Fri May 16, 2008 9:53 pm UTC
Forum: Mathematics
Topic: Encrypted letter to Fermilab
Replies: 15
Views: 5248

Re: Encrypted letter to Fermilab

We could also take the 2's to mean 0s... at that point you'd have a binary sequence. I started translating it to hex and seeing what the pattern meant when put through the middle code ring, but no luck.

Go to advanced search